Radiation Protection Distance Learning Project

Radiation Protection Distance Learning Project Module 3.4 - Safe Handling Of Radioactive WasteINTERNATIONAL ATOMIC ENERGY AGENCYAUSTRALIAN NUCLEAR SCIENCE AND TECHNOLOGY ORGANISATIONDISTANCE LEARNING MATERIALSRADIATION PROTECTIONModule 3.4Prepared by Safety and Radiation Science Australian Nuclear Science and Technology Organisation With the assistance of consultants in Australia and the United Kingdom, and IAEA experts from Korea, Mongolia, New Zealand, the Philippines and ThailandUse of this material, acknowledging the IAEA and ANSTO as the source, is permitted for non-profit trainingProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Module 3.4 - Safe Handling Of Radioactive WasteAcknowledgementsThis material has been prepared by an extensive team of international experts from the fields of radiation protection, medicine and education. It is not possible to mention by name all those who have had an input to; the initial planning; writing modules and workbooks; preparing and marking final assignments; proof-reading and editing; using the material and providing valuable feedback; organizing and hosting review meetings; and general administrative support.The support of ANSTO management in providing the resource and encouragement is gratefully acknowledged.The enthusiastic support of IAEA Technical Officers has been vital to the success of this project.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 1 Module 3.4 - Safe Handling Of Radioactive WastePART 3RADIATION PROTECTION INFRASTRUCTUREMODULE 3.4SAFE HANDLING OF RADIOACTIVE WASTECONTENTSOVERVIEW...... 4 TIME ALLOCATION...... 5 MATERIALS...... 5 LEARNING OBJECTIVES...... 6 1. DEFINITION OF RADIOACTIVE WASTE...... 7 2. RADIOACTIVE WASTE MANAGEMENT...... 7 2.1 Objective...... 7 2.2 Waste Minimization...... 8 2.3 A Radioactive Waste Management Programme...... 9 SELF CHECK 1...... 10 3. CLASSIFICATION OF RADIOACTIVE WASTE...... 11 3.1 Environmental Discharges...... 11 3.2 Specific Guidance For Liquid Waste...... 11 3.3 Solid Waste...... 12 3.4 International Waste Classes...... 13 3.4.1 Exempt waste (EW)...... 13 ACTIVITY...... 14 3.4.2 Low intermediate level waste (LILW)...... 14 3.4.3 High-level waste (HLW)...... 15 SELF CHECK 2...... 16 4. INTERNATIONAL AND NATIONAL PROGRAMMES...... 17 4.1 The Role Of The IAEA...... 17 4.2 International Co-operation...... 18 4.3 National Framework For The Management Of Radioactive Waste.18 SELF CHECK 3...... 19Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 2 Module 3.4 - Safe Handling Of Radioactive Waste5. AUTHORIZATIONS...... 20 5.1 Authorizations For The Storage Of Waste...... 20 5.2 Authorizations For Waste Disposal...... 21 5.3 Discharges Into The Environment...... 21 5.3.1 Critical groups...... 22 5.3.2 Determining discharge limits...... 24 5.3.3 Dose estimates...... 27 SELF CHECK 4...... 28 6. BASIC STEPS IN RADIOACTIVE WASTE MANAGEMENT...... 29 6.1 Disposal And Predisposal...... 30 6.2 Pretreatment...... 31 6.2.1 Segregation...... 31 6.2.2 Chemical adjustment...... 33 6.2.3 Decontamination...... 33 SELF CHECK 5...... 33 6.3 Treatment...... 34 6.3.1 Volume reduction...... 35 6.3.1.1 Compaction...... 35 6.3.1.2 Incineration...... 36 6.3.2 Change of composition...... 36 6.3.3 Radionuclide removal...... 37 6.4 Conditioning...... 37 6.4.1 Immobilization...... 37 6.4.2 Packaging...... 38 SELF CHECK 6...... 38 7. CONTROLLING RADIOLOGICAL HAZARDS...... 39 8. MONITORING LEVELS OF RADIOACTIVITY IN RADIOACTIVE WASTE ...... 40 8.1 Monitoring Methods...... 40 8.2 Estimating The Activity Of Waste...... 41 8.2.1 Solid waste...... 41 8.2.2 Gaseous and liquid waste...... 42 SELF CHECK 7...... 43 9. STORAGE OF RADIOACTIVE WASTE...... 44 9.1 Operational Convenience...... 44Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 3 Module 3.4 - Safe Handling Of Radioactive Waste9.2 Storage...... 46 10. RECORDS...... 48 SELF CHECK 8...... 49 APPENDIX 1...... 54 APPENDIX 2...... 56 APPENDIX 3...... 66 GLOSSARY...... 73 REFERENCES:...... 78Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 4 Module 3.4 - Safe Handling Of Radioactive WasteOVERVIEWThe use of radioactive material in industrial applications, research and medicine, as well as in the generation of nuclear power, gives rise to radioactive waste. The importance of safe management of radioactive waste for the protection of human health and the environment has long been recognized and much experience has been gained in this field. The International Atomic Energy Agency (IAEA) has developed and published standards and guidelines for radioactive waste management, which have been adopted internationally. Radioactive waste may occur in any of three physical forms (gaseous, liquid and solid) and range in concentration from trivial to highly concentrated. Storage and disposal methods will vary according to the form of the waste, the radionuclides present, their concentration and radiotoxicity.In this module, you will learn methods of managing radioactive waste safely in order to minimize hazards to people and the environment. The module is designed for users of radioactive materials and addresses issues associated with waste classification, safe storage and appropriate processing to make the waste safe for disposal. Note that radiological hazards exist at all stages of waste handling and must be controlled. You have learnt about methods of hazard control in previous modules and it will not be covered in detail in this module. If you are unsure of appropriate techniques for the control of radiological hazards, you should revise the modules in Part 2 before commencing this module.This module is not intended to address the requirements for waste repositories.Before studying this module you should have completed the modules in parts 1 and 2.  TIME ALLOCATIONProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 5 Module 3.4 - Safe Handling Of Radioactive WasteIt is estimated that you will need to spend 15 hours to complete this module before commencing the assignment. The estimated time is for your guidance only. If you would like to spend more time on the module to understand it more fully, then by all means do so.MATERIALSYou will need writing materials and your workbook while studying this module.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 6 Module 3.4 - Safe Handling Of Radioactive WasteLEARNING OBJECTIVESWhen you have completed this module you will be able to do the following:1) Define radioactive waste. 2) State the main objective of radioactive waste management.3) Classify waste into various classes according to properties.4) Explain why liquid and gaseous waste requires special treatment.5) Describe the role of the IAEA in the management of radioactive waste.6) Describe the input of national legislation to the management of radioactive waste.7) State the limitations on simple screening calculations for determining discharge limits or calculating potential doses.8) Use the terms pretreatment, treatment and conditioning accurately.9) Describe requirements for the safe storage of waste in the workplace.10)Describe how radiological hazards are controlled in waste processing.11)State the importance of good record keeping and list the characteristics of radioactive waste that should be recorded.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 7 Module 3.4 - Safe Handling Of Radioactive WasteNOW YOU ARE READY TO START WORK1. DEFINITION OF RADIOACTIVE WASTEWhat do we really mean when we use the term “radioactive waste”? The IAEA defines radioactive waste as “ any material that contains or is contaminated with radionuclides at concentrations or radioactivity levels greater than ‘exempt quantities’ established by the competent regulatory authorities and for which no further use is foreseen.”It should be recognized that this definition is purely for regulatory purposes, and that material with activity concentrations equal to or less than clearance levels is radioactive, although the associated radiological hazards are negligible.Although a lot of waste can easily be identified as that “for which no further use is seen”, such as soiled tissues, care needs to be taken applying this definition when some of the waste may be recycled. Some examples of recycling could be smelting contaminated scrap steel, radioactive sources that are too small for one application but could be used for another, or further use of uranium and plutonium from spent nuclear fuel. It should be remembered that whether the radioactive material is recycled or disposed of as radioactive waste, it must be controlled as required by the national Regulatory Authority.2. RADIOACTIVE WASTE MANAGEMENT2.1 Objective Radioactive materials are potentially hazardous if they are not controlled. In addition to the controls on the use of radioactive materials, it is very important that the disposal of waste containing radioactive materials is also controlled. Effective control of radioactive waste prevents unnecessaryProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 8 Module 3.4 - Safe Handling Of Radioactive Waste radiation exposure that may be harmful to people or the environment. Since many radioactive materials have long half lives, some controls are required many years and even for many generations after the disposal. Therefore, it is vital that in countries where radioactive materials are used, there is an ongoing national Radioactive Waste Management Programme to control the disposal of radioactive materials.The internationally agreed objective of radioactive waste management is to deal with radioactive waste in a manner that protects human health and the environment now and in the future, without imposing undue burdens on future generations.Radioactive waste in the environment can have an effect on organisms other than man. However, since humans are among the most radiation sensitive organisms, safety standards that are sufficiently restrictive to protect humans will also protect other species.The possible impact on the human health and environment of neighbouring countries should be taken into account by the waste management practices of a particular country. The radiological impact on human health and the environment in other countries should be no more than those judged acceptable within the country of origin of the waste. In fulfilling this duty, a country should take into account the recommendations of international bodies such as the ICRP and IAEA. In particular IAEA Safety Series 67 “Assigning A Value To Transboundary Radiation Exposure” covers the potential effect of waste disposal processes on other countries.2.2 Waste MinimizationGood waste management minimizes the amount of radioactive waste generated, thus minimizing the hazard and maximizing the use of space in disposal facilities.Waste minimization can be achieved in a number of ways. Effective waste minimization typically employs a combination of more than one technique. Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 9 Module 3.4 - Safe Handling Of Radioactive Waste Delay and decay – Store short half life material to allow decay to levels below exemption levels. Dilute and disperse – provide sufficient dilution of liquid and gaseous wastes to below exemption levels. Review work practices to minimize quantities of radioactive material used where possible.Do not allow unnecessary materials to go into areas where they are likely to become contaminated! 2.3 A Radioactive Waste Management Programme The control of radioactive waste is achieved by an effective waste management programme. The programme, shown schematically in Figure 1, prescribes processes which may be required to ensure that waste can be disposed of safely.Figure 1 Structure of a radioactive waste management programme.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 10 Module 3.4 - Safe Handling Of Radioactive WasteYou may find it useful to refer back to Figure 1 while studying the module.Processing is divided into pretreatment, treatment and conditioning, all of which will be explained in section 6. Storage and transport may occur at any stage.SELF CHECK 1Now see how much you have understood by answering the following1. What is the regulatory definition of radioactive waste?2. What is the main objective of radioactive waste management?3. What are 3 ways of minimizing radioactive waste?4. Using the outline in your workbook, fill in the missing steps in radioactive waste management programme structure using the following word list. activity removal disposal processing change of composition immobilization segregation chemical adjustment overpack storage collection packaging treatment conditioning predisposal transport decontamination pretreatment volume reductionNow check your answers with the model answers in your workbook.3. CLASSIFICATION OF RADIOACTIVE WASTEA suitable classification system for radioactive waste will help to plan the safe disposal of the material. The classification includes the relatively simpleProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 11 Module 3.4 - Safe Handling Of Radioactive Waste classification of solid, liquids and gases and also whether the material is to be discharged to the environment or whether it is to be disposed of in a landfill or a specially built facility. Liquid aqueous wastes are classified further according to concentration of radioactive material. A more complicated classification by activity level and half-life gives the opportunity for specific guidance to be given on disposal of materials.3.1 Environmental Discharges Radioactive materials that are discharged directly into the environment and dispersed by it, are usually liquids or gases. Solid waste is not discharged directly to the environment as it can be controlled at the point of production and placed in containers for decay or disposal to a suitable solid waste disposal site. Generally, environmental discharges are the effluent from a practice where radioactive materials are being used. Examples of liquid effluent are radioactive materials disposed of down laboratory drains and the contents of discharge lines from industries such as phosphoric acid or rare earth extraction plants. Examples of atmospheric releases are via the stacks of fume cupboards in which radioactive materials are being used or a licensed incinerator where combustible materials contaminated with radioactive materials are being burned. Note that ash from incinerator stacks (solid material) could enter the environment unless it has been filtered out.3.2 Specific Guidance For Liquid Waste If highly contaminated liquids or liquids containing significant alpha activity are produced as waste, they are not suitable for discharge into the environment and are treated prior to disposal. Section 6 will describe treatment methods. Table 1 gives IAEA guidance on liquid waste. Note that the activity concentrations in the table do not apply to liquids containing alpha emitting nuclides.Table 1 IAEA classifications for radioactive liquid waste. Waste class Activity m-3 RemarksProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 12 Module 3.4 - Safe Handling Of Radioactive Waste mixed / emitters LOW LEVEL <37 kBq No treatment required: Release after measurement.*37 kBq to 37MBq Treat. No shielding required.37MBq to 3.7GBq Treat. Shielding sometimes required according to the radionuclide composition.Intermediate Waste. 3.7GBq to 370TBq Treat. Shielding necessary in all cases.From “Handling and Treatment of Radioactive Aqueous Waste” IAEA TECDOC-654(1992) * Releases require authorization (see Section 5).3.3 Solid Waste Solid waste includes general lab waste, such as tissues and gloves, used filter units, source capsules from nuclear gauges and bulk solid materials, such as the residue from rare earth extraction processes or uranium mining.Later in the module, you will learn how solid waste is managed and prepared for disposal.3.4 International Waste Classes Radioactive waste is classified in order to assist in the determination of appropriate disposal methods.The IAEA have defined waste classes by their activity level and the amount of heat generated by the radioactive material. The latest version is contained in the document IAEA Safety Series No 111-G-1.1 (1994). The following figure shows a matrix of radioactivity levels and decay periods. There are three main areas in the matrix, Exempt Waste (EW), Low Intermediate LevelProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 13 Module 3.4 - Safe Handling Of Radioactive WasteWaste (LILW) and High Level Waste (HLW). The LILW area on the matrix is subdivided into two areas according to radiological half lives (short lived (SL) and long lived (LL)). Figure 2 Waste classification system.3.4.1 Exempt waste (EW) Exempt waste is waste excluded from regulatory control because its radiological hazards are negligible. Regulatory Authorities establish exemption levels or clearance levels in terms of activity concentration and total activity. IAEA BSS 115 Schedule I gives examples of clearance levels.ACTIVITYFind out how waste is classified as exempt in your country. Discuss your findings with your supervisor.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 14 Module 3.4 - Safe Handling Of Radioactive Waste3.4.2 Low intermediate level waste (LILW) Low intermediate level waste is typically divided into short-lived (SL) and long lived (LL) waste. Short lived waste (LILW-SL) does not contain significant levels of radionuclides with half lives greater than 30 years. As a guide, activity concentrations of long lived alpha emitters may be limited to an average of 400 Bq g-1 with a maximum package limit of 4000 Bq g-1. Disposal may be to a near surface repository. Long lived waste (LILW-LL) contains long lived radionuclides in quantities that need a high degree of isolation from the biosphere. Recommended disposal is in deep geological formations. The following are examples of materials which may be classified as LILW if the levels of total activity or radioactive concentrations are above the exemption levels. ion exchange resins and filter materials used to clean water at a nuclear power plant. research equipment from laboratories where radioactive materials are used. shoe covers, lab coats, cleaning cloths, paper towels, etc., used in an area where radioactive material is present. containers, cloth, paper, fluids, and equipment which came in contact with radioactive materials used in hospitals to diagnose or treat disease. filters from sampling devices used to test for airborne radioactive contamination. scintillation fluids in which filters from some sampling devices must be dissolved in order to determine the amount of radioactive material present.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 15 Module 3.4 - Safe Handling Of Radioactive Waste carcasses of animals treated with radioactive materials used in medical or pharmaceutical research.3.4.3 High-level waste (HLW) High level waste is waste that is sufficiently radioactive to require both shielding and cooling. High level waste has concentrations of long lived radionuclides which exceed the limits for LILW-SL and the radioactive decay process produces heat at a rate above about 2kW m-3.HLW is generated during the reprocessing of spent nuclear fuel elements. The waste contains significant levels of alpha emitters (mainly transuranics with long half-lives) and mixed fission products including radionuclides such as Caesium-134 and 137, Strontium-90, and Technetium-99. The waste contains high levels of activity and generates enough heat of decay to require special cooling arrangements.The waste classes and recommended disposal options are further described in Table 6 in the appendix.SELF CHECK 2Now see how much you have understood by answering the following1. What characteristics of radioactive waste are used to classify it?2. Why is liquid/gaseous waste treated differently to solid waste?3. What is the level (in Bq g-1) at which radioactive waste for each of the following radioisotopes is considered exempt waste in your country?3H, 32P, 60Co, 90Sr/90Y, 99mTc, 131I, 241Am4. How is low intermediate level waste subdivided?5. What are the two main characteristics of high level waste?6. Determine an appropriate waste classification for the following:Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 16 Module 3.4 - Safe Handling Of Radioactive Waste a) 100 TBq Co-60 source no longer required for a teletherapy unit. b) 200 kBq I-131 in the discharge to the sewer of a nuclear medicine department. c) The liquor resulting from reprocessing of nuclear fuel. d) General lab waste containing material contaminated with tritium, Cs-134, Kr-85 and Co-60. e) Contaminated lab coat after technician works with Tc-99m. Now check your answers with the model answers in your workbook.4. INTERNATIONAL AND NATIONAL PROGRAMMES4.1 The Role Of The IAEA The IAEA has been assisting member states in the management of radioactive waste for around three decades. An integrated waste management programme exists to help member states in the safe and effective management of radioactive waste. The IAEA programmes are summarized in Table 2. The international exchange of technical information facilitated by the Agency’s waste management programme has led to the development of standards and criteria for the handling, treatment, conditioning, storage and disposal of radioactive waste of all classes. As a result of these activities many Safety Series and Technical Reports Series documents have been published.Table 2 Programmes established in the IAEA for Radiation Waste Management RADWASS Radioactive Waste A series of international consensus Management Safety documents designed to make more Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 17 Module 3.4 - Safe Handling Of Radioactive WasteStandards evident the harmonization in approaches to the safe management of radioactive waste particularly in regards to waste disposal issues. WATAC Radioactive Waste The role of this committee is to provide a Technology Advisory forum for the exchange of scientific and Committee technical information of national and international importance and to advise the Agency on its activities in the area of radioactive waste technology and on generic radioactive waste management. WASSAC Waste Safety The primary role is providing advice on Standards Advisory the development and revision of the Committee Agency’s RADWASS series documents. WAMAP Radioactive Waste Provides a technical assistance Management mechanism offering expertise on waste Advisory Programme management problems faced by developing countries.WATRP Waste Management Provides a forum for technical Assessment and assessments or peer review of waste Technical Review management policies and practices of Programme industrialized countries. 4.2 International Co-operation International co-operation has been encouraged through the development of the Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management.This convention is a legal instrument (effectively a law for the member states) requiring member states who sign the convention to undertake certain actions in regard to spent fuel and radioactive waste management. The objectives of the convention is to achieve and maintain a high level ofProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 18 Module 3.4 - Safe Handling Of Radioactive Waste safety worldwide in the management of spent fuel and radioactive waste through the enhancement of national measures and international co- operation. It is also aimed at preventing accidents with radiological consequences and mitigating their consequences should they occur during the management of spent fuel and radioactive waste.4.3 National Framework For The Management Of Radioactive Waste A national framework for waste management is necessary to protect the country’s citizens (and those in surrounding countries) from unnecessary exposure to radioactive materials.The basic requirements of a national framework should be defined in the Regulatory Authorities regulations dealing with radioactive materials. The following issues should be considered: Setting levels of radioactivity or radioactive concentrations at which regulatory control is required. (These levels may be taken from IAEA Safety Series documents.) Specifying public dose constraints which should be met in the disposal of radioactive waste. (IAEA Safety series documents, such as IAEA Safety Standards Series No WS-G-2.3, “Regulatory Control Of Radioactive Discharges into the Environment”, give guidance on setting appropriate dose constraints.) Having in place a system of authorizations for discharge, disposal and storage of radioactive waste. (This should also include advice on waste treatment and disposal options.) Specifying the monitoring requirements for the measurement of waste, and where necessary monitoring the environment. The keeping of appropriate records of measurements and waste disposal.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 19 Module 3.4 - Safe Handling Of Radioactive Waste Requiring a quality system to ensure the action taken and records kept are appropriate.SELF CHECK 3Now see how much you have understood by answering the following1. What is the role of the IAEA in the management of radioactive waste?2. What issues should you consider when establishing a national framework to deal with radioactive waste?Now check your answers with the model answers in your workbook.5. AUTHORIZATIONSRadioactive materials which are above the level subject to regulatory control are used under an authorization issued by the Regulatory Authority. The storage, treatment and disposal of radioactive waste must also be subject to authorization. The uncontrolled disposal of radioactive waste could expose large sections of the public, as well as occupationally exposed people. Authorizations are important in order to ensure radioactive waste is dealt with safely and meets the goals of protecting human health and the environment.IAEA recommendations on waste disposal and discharges into the environment are a good basis for the specific national requirements for authorization of radioactive waste discharges and disposals. Typical requirements for authorizations and their compliance are discussed below.5.1 Authorizations For The Storage Of Waste Authorization to store radioactive waste is dependent on consideration of the physical security of the waste, the doses workers might be exposed to fromProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 20 Module 3.4 - Safe Handling Of Radioactive Waste the store, and the potential for accidental releases of the waste into the environment. The authorization application should state the following as minimum information. The radionuclides to be stored. The maximum activities to be stored. The form of the waste, e.g. liquid scintillant, paper etc. The storage period. Details of the store and the containers the waste will be kept in. The reason for storage. For example, to allow decay or awaiting disposal.The authorization will specify the radionuclides, their maximum activities and the period of time for which the waste can be stored on site. The storage conditions may also be specified.5.2 Authorizations For Waste Disposal An authorization for the disposal of waste will specify the quantities of isotopes which can be disposed of during a certain time interval and will state the disposal site (e.g. landfill, incinerator, or waste processing plant). The activity limit will probably be a simple fraction of the activity the disposal facility is allowed to receive for that period.5.3 Discharges Into The Environment Discharge of waste into the environment is a special case of disposal and requires very careful regulation. The waste is moving away from the control of any authority or organization and into the biosphere with potential for intake by people directly or through the food chain.The radiation exposure any person might receive from contact with the discharged material must not exceed dose limits, should be within doseProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 21 Module 3.4 - Safe Handling Of Radioactive Waste constraints and be considered to be ALARA. Although the radiation exposure to an exposed person is the limiting factor, for convenience the authorization to discharge to the environment will usually specify the maximum activity of the radioactive waste that can be discharged. This may be in the form of the total activity discharged either per year, week, month or quarter. To enable the Regulatory Authority to determine if the requested discharge is acceptable, the following information would be the minimum provided. The radionuclides to be discharged. Details of the type of waste and the method of discharge. For example, “liquids from radioisotope laboratory drains discharged to a river via the site effluent line”. The activity of the waste to be discharged and at what frequency. Any dilution before or after it leaves the operators control. An estimate of the potential public and any worker doses from the discharge. An explanation why the waste should be discharged to the environment and not treated and sent for long term storage. This could include a simple ALARA assessment.Discharges of radioactive materials directly into the environment are usually liquids or gases. The approved discharge levels specified in the authorization will be based on calculations of the radiation dose a person might receive from ingesting water contaminated by the waste, or from breathing the gas. 5.3.1 Critical groups When discharging liquid or gaseous waste into the environment, it is important to create a hypothetical group of people who will be the most likely affected by contact with radioactive materials. The group of people is calledProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 22 Module 3.4 - Safe Handling Of Radioactive Waste the critical group. By taking into consideration the radioisotope, its pathway into the body and the probability of the group coming into contact with the effluent, it is possible to predict a worst case scenario and calculate potential doses from the discharge. The critical group is the group that would receive the greatest dose. The product of the age related dose conversion factor (from IAEA BSS 115) and the intake for that age group will indicate what age group should be used as the critical group. The effect of radiation on children is greater than that on adults, so the critical group is often children or infants. The discharge limits are often based on the potential effect on children rather than adults.Consider the following examples: Table 3 is used to determine the critical group when considering the disposal of tritiated water into a river from which drinking water is drawn. Notice that the significant pathway is ingestion, therefore the data in the table refers to the ingestion of water.Table 3 Determination Of Critical Group Due To Ingestion Of Tritiated Water. Age Group. Dose conversion Annual water Product of dose factor, ingestion* intake# factor and water intake. (Sv Bq-1) (m3 day-1) infant (1y) 6.4 x 10-11 0.260 1.67 x 10-11 adult (male*) 1.8 x 10-11 0.600 1.08 x 10-11* IAEA BSS No.115 # Safety Report Series No.19 Study the table. Which is the critical group? You should notice that infants are the critical group since the product of the does conversion factor and the annual water intake is greatest for this group. Table 4 is used to determine the critical group when considering the disposal of gaseous I-131 through a stack and the inhalation pathway.Table 4Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 23 Module 3.4 - Safe Handling Of Radioactive WasteDetermination Of Critical Group Due To Inhalation Of Gaseous I-131. Age Group. Dose conversion Inhalation rate# Product of dose factor, inhalation* factor and (m3 day-1) inhalation rate*. (Sv Bq-1) infant (1y) 7.2 x 10-8 5.16 3.7 x 10-7 child (10y) 1.9 x 10-8 15.3 2.9 x 10-7 adult (male*) 7.4 x 10-9 22.2 1.6 x 10-7* IAEA BSS No.115 # ICRP 71 Study the table. Which is the critical group? You should have noticed that infants are the critical group since the product of the dose conversion factor and the inhalation rate is greatest for this group.5.3.2 Determining discharge limits In order to determine discharge limits, it is necessary to go through the following steps: Choose a model.Usually a ‘worst case’ scenario, using relatively simple concepts, is chosen for screening purposes. This will determine whether the discharge limits are realistic. It may then be necessary to repeat the process using a more complex model requiring more data. Consider the most significant exposure pathways.Exposure pathways include inhalation, external exposure and ingestion by direct drinking of water or indirectly through food. Sometimes the significance of each pathway will be obvious. It may depend heavily on whether the discharge is a single event or is continuous and expected to take place over many years. Sometimes it is necessary to go through the calculation process to determine the significance. Determine the critical group.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 24 Module 3.4 - Safe Handling Of Radioactive WasteYou need to have decided the most significant pathway. Then the critical group is determined as explained in Section 5.3.1. Collect appropriate data.The data will include information such as total liquid discharge and water flow information for liquid discharges to a river, and information about the stack flow for gaseous discharges. You will also need dose conversion factors and intake parameters. Apply a dose constraint.The dose constraint will be provided by the Regulatory Authority. Use the above information to find out the maximum activity which can be discharged that would give a dose to members of the critical group equal to the dose constraint.The following examples for liquid waste and gaseous waste show you how to determine discharge limits in a simple way. Refer to Appendix 2 for the calculations. Remember that here we have simplified the process in order to help you understand it. Your objective is to understand how discharge limits are applied and what simplifications and assumptions have to be made. The information in the Appendix will help this, but it is recommended that you work through the examples later, preferably after you have worked through the rest of the module.LIQUID WASTE EXAMPLEA laboratory wants to discharge tritiated water into a local river. The river passes a water treatment plant where the water is taken, treated (with no further dilution) and supplied to the local town as drinking water. The laboratory must provide information about the proposed discharge to the Regulatory Authority who will then check the details and the projected doses to the public and any potentially exposed worker, prior to issuing an authorization and setting a limit on the discharge.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 25 Module 3.4 - Safe Handling Of Radioactive WasteThe tritiated water is disposed of through a sink drain into the site effluent, which has a discharge rate to the river of 10 000 m3 per week.The river has a flow rate of 100 000 m3 per week.The Regulatory Authority will determine an average weekly discharge limit which will comply with the annual dose constraint of 0.1 mSv.To determine the discharge limit, we need to go through the six steps above. The following table shows how to do this.Table 5Discharge to river. River is the only sourceModel of drinking water for the critical group. No further dilution. River is not used for crop irrigation. Significant exposure pathways Ingestion – direct drinking of water.Critical group Infants from Table 3Data Lab discharge rate = 10 000 m3 per week. River flow rate = 100 000 m3 per week. Dose conversion factor (infants) = 6.4 x 10-11 Sv Bq-1. Annual intake (infants) = 0.260 m3 Dose constraint 0.1 mSvDischarge limit Can be calculated from above data (see Appendix 2).GASEOUS WASTE EXAMPLEA radioisotope production plant is seeking authority to discharge gaseous iodine-131 from its stack. The plant must provide information about the proposed discharge to the Regulatory Authority who will then check the details, prior to issuing an authorization and setting a limit on the discharge. The stack is 60m tall and the cross-sectional area of the stack at the point of release is 0.7 m2. The velocity of the discharge is 15 ms-1.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 26 Module 3.4 - Safe Handling Of Radioactive WasteTo determine the discharge limit, we need to go through the six steps above. The following table shows how to do this.Concentration of radionuclide for the critical group is the same as at the point of release (top of the stack).Model Fraction of time the wind blows towards the point of interest is 0.25. (Note that the height of the stack does not come into the chosen model. It may be used for a more complex model.) Inhalation. Calculation shows that external radiation dose is insignificant to the Significant exposure pathways inhalation dose. In a more complex model, it would be necessary to determine the intake by ingestion, particularly milk.Critical group Infants – refer to Table 4Data Velocity of discharge = 15 ms-1.Cross-sectional area of stack = 0.7 m2.Dose conversion factor (infants) = 7.2 x 10-8 Sv Bq-1. Annual inhalation rate (infants) = 5.16 m3 Dose constraint 0.1 mSvDischarge limit Can be calculated from above data (see Appendix 2).Note that both these examples are simple scenarios. In reality, you will encounter discharges that have more than one radionuclide present and the limit that is imposed by the Regulatory Authority will include ALL radionuclides and ALL pathways.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 27 Module 3.4 - Safe Handling Of Radioactive Waste5.3.3 Dose estimates Potential doses to people as a result of planned or actual liquid or airborne discharges require estimating for the following reasons: To provide data to the Regulatory Authority when requesting discharge authorization. To ensure that doses are ALARA. To ensure that doses are in compliance with dose constraints.To following list is the steps that need to be taken to estimate doses. Determine the nuclides and quantities discharged. Determine the pathways by which these nuclides may cause exposure. Determine the location and habits of the people who may be exposed. If necessary, assume a ‘worst case’ scenario. Calculate the doses from the individual nuclides in the discharge from each possible pathway. Sum the doses.Appendix 3 has some simple examples of estimating doses.Remember that, in reality, there are many more contributing factors to doses from both liquid and gaseous waste. Radioactivity is deposited on the ground and absorbed by plants and animals, usually from more than one radioisotope. People are exposed to radioactive material that has been absorbed by grains and vegetables, from meat and fish and milk may be a contributing factor. If you need to take these factors into consideration, please refer to IAEA Safety Reports Series No. 19 “Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substance to the Environment” (2001).Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 28 Module 3.4 - Safe Handling Of Radioactive WasteSELF CHECK 4Now see how much you have understood by answering the following1. What information should be provided to the Regulatory Authority when seeking authorization to: a) discharge liquid waste? b) store waste while waiting for disposal?2. What does the term ‘critical group’ mean and how is it used?3. List the 6 steps in determining discharge limits.4. What is a screening calculation?5. List some of the data required in order to calculate discharge limits for airborne effluent.6. Why is it necessary to estimate doses from discharges to the environment?7. List some of the limitations of simple dose estimation calculations.Now check your answers with the model answers in your workbook.6. BASIC STEPS IN RADIOACTIVE WASTE MANAGEMENTEffective management of radioactive waste considers the steps (shown schematically in Figure 3) in the radioactive waste management process as parts of a total system, from control of its generation through to disposal. It should be noted that characterization, storage and transportation may take place between any of the waste management steps. Figure 3 shows the three basic steps in processing radioactive waste prior to disposal. The waste may be reclassified as exempt waste or removed from the waste stream for reuse at any stage.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 29 Module 3.4 - Safe Handling Of Radioactive WasteFigure 3 Basic Steps of Radioactive Waste Management.6.1 Disposal And Predisposal Disposal is the final step in radioactive waste management in which radioactive waste is discharged into the environment or is placed into a disposal facility, without the intention of retrieval and without reliance on long term surveillance and maintenance. Discharge of liquid and gaseous effluents into the environment with subsequent dispersion (dilute and disperse) must be within authorized limits. This is an irreversible action and is considered suitable only for limited amounts of specified waste.Safety in a disposal facility is achieved by containment and isolation of suitably conditioned waste by a multilayer barrier system, either natural and/or engineered, to restrict the release of the radionuclides into the environment. The barrier system is designed according to the disposal option chosen and the radioactive waste forms involved.Predisposal is all the steps which have to be carried out prior to disposal of the waste. The rest of section 6 will describe predisposal activities.Radiological hazards exist in all predisposal processes. Radiation protection practices must be in place to control personnel exposure to radiation and contamination. Time, distance and shielding must be used to minimizeProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 30 Module 3.4 - Safe Handling Of Radioactive Waste worker’s exposure to radiation dose rates. Contamination control methods, using containment, access control, surface and airborne monitoring and personal protective equipment, as appropriate, must be used. (Refer to Section 7)Also remember that other hazards, such as chemical and manual handling, may be present and must be controlled.6.2 PretreatmentFigure 4 Steps in pretreatment Pretreatment of waste is the initial step in waste management after waste generation. It consists of collection, segregation, chemical adjustment and decontamination and may also include a period of interim storage. This initial step is important as it provides the best opportunity to segregate waste streams for recycling, disposal as ordinary non-radioactive waste (when the quantities of radioactive materials are exempt from regulatory controls) or storage to allow decay (to reduce the dose rates and hence the radiological hazards during any further treatment).Following pretreatment, the material may follow several pathways. It may be suitable for reuse, may require treatment or may be classified as exempt waste.6.2.1 SegregationWaste segregation should occur in the workplace where the waste is generated. Further segregation may be necessary at the waste management facility. Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 31 Module 3.4 - Safe Handling Of Radioactive WasteWaste can be segregated according to the following characteristics. Active and Non-Active (see Figure 5). Half-life. Radiation types and energies. Appropriate treatment methods.Segregation based on radioisotope half lives allows for the possible storage and decay of short lived radioisotopes. When the activity is below the required clearance levels, it can be disposed of as exempt waste. This reduces the amount of radioactive waste which requires special disposal or discharge requirements. For example short lived radioisotopes such as Technetium-99m (6 hour half life) could be stored for a number of half-lives, after which time it could be disposed of. Typically, ten half-lives are suggested as a start point as this gives a reduction of approximately 1/1000, however remember that the initial activity of the waste determines if ten half- lives is enough. In the case of Technetium-99m, ten half-lives is equal to only 60 hours, or 2.5 days. Whereas the activity of Iridium-192 (74 day half life) contaminated waste would have reduced very little in the same 2.5 day period. Some organizations set a limit on the maximum half-live for isotopes that will be stored for decay. As a guide 8.5 days is one figure which is used. (This will allow for the possible storage for decay of Iodine-131.)As well as segregating by half life, it may be necessary to segregate waste containing radionuclides that are hard to measure. For example, low energy beta and alpha emitters would require careful monitoring using specialized techniques.Alpha emitting waste has high radiotoxicities. It should be segregated ! at the source and monitored before it joins a specialized waste stream.Segregation of types of waste for different treatment methods, such as compaction or incineration, is also important.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 32 Module 3.4 - Safe Handling Of Radioactive WasteActive waste bin Non-active waste bin Figure 5 Active and non-active waste bins6.2.2 Chemical adjustmentChemical adjustment makes the waste safer to handle through chemical methods. An example of this is adding a buffer to liquid waste that is too acidic for further treatment. By adding the buffer, the pH is lowered and therefore, the waste can be moved to the next process.6.2.3 DecontaminationEssentially, this is checking that the outer surface of the waste container is not contaminated. Before moving any waste container, make sure it is not contaminated by conducting a smear/wipe test on the outer surface of the container. When the container has reached its destination, another wipe test should be carried out, particularly when transporting liquid waste. Ordinary cleaning products can be used to decontaminate a surface. Make sure that the paper towel/cloth used to clean a surface is disposed of/treated as solid radioactive waste.SELF CHECK 5Now see how much you have understood by answering the following.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 33 Module 3.4 - Safe Handling Of Radioactive Waste1. Explain the terms disposal and predisposal.2. What characteristics of waste are used to segregate it at the point of generation?Now check your answers with the model answers in your workbook.6.3 TreatmentFigure 6 Steps in treatment Treatment of radioactive waste includes processes intended to improve safety or economy by changing the physical or chemical characteristics of the radioactive waste. Basic treatment concepts and examples include: volume reduction  change of composition  radionuclide removal Treatment may generate secondary radioactive waste to be managed, e.g. contaminated filters, spent resins and sludges.Following treatment, some material may be suitable for reuse and some may be disposed of as exempt waste. After treatment, the waste may or may not be conditioned prior to disposal.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 34 Module 3.4 - Safe Handling Of Radioactive Waste6.3.1 Volume reductionIt is common practice to reduce the volume of radioactive waste to make handling and treatment (and ultimately, disposal) easier. There are two commonly used methods, compaction and incineration.6.3.1.1 Compaction One method of minimizing the physical quantity of waste to be handled is to reduce the volume of the waste by compaction. A high pressure press is used to ‘squash’ the waste. (See Figure 7)Waste suitable for compaction includes paper, glass or plastic bottles, cloth, wood, metal drums. You can probably think of a few other examples.Compaction does not reduce the activity of the waste only its volume.Figure 7 Drum CompactusProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 35 Module 3.4 - Safe Handling Of Radioactive Waste6.3.1.2 Incineration If the waste consists of contaminated combustible materials, incinerating the materials will reduce their volume. The incinerator must be authorized to incinerate radioactive waste. The license should consider the dose to workers and members of the public from radioactive waste which might be discharged from the stack with hot gases. Gas scrubbers and precipitators may be required to reduce these discharges.The ash left from the incineration of radioactive waste will contain concentrated levels of radioactive material. If burning a particular material reduces the volume by a factor of 1000, the concentration will now increase by a factor of 1000, assuming that none has been caught on filters or gone up the stack. (There is less material through which the radioactive material is spread.) The ash therefore needs to be examined for disposal as solid radioactive waste. However, if the radioactive waste is incinerated with relatively large volumes of non-radioactive waste the radioactive ash might now be diluted with the non-radioactive ash and have a lower concentration.Incineration is used successfully for common combustible materials such as paper. It has also been used successfully for other materials such as hydrocarbon sludge containing low levels of Radium-226 scale.As with compaction, incineration does not reduce the activity of the waste, only its volume. However, there is the potential for the reduction of the concentration of the ash if large volumes of non-radioactive waste are incinerated with the radioactive waste.6.3.2 Change of composition Chemical methods may be used to change the composition of the waste by precipitating dissolved solids from large volumes of liquid waste. This process may also include flocculation, which causes finely divided precipitate to join together and form larger particles. Methods such as this are used for the treatment of large volumes of liquid waste resulting from the manufacture of radioisotopes and also in theProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 36 Module 3.4 - Safe Handling Of Radioactive Waste production of rare earth materials from sands or ores containing naturally occurring materials.A change in the composition of the waste can be followed by processes to separate the radioactive material.6.3.3 Radionuclide removal Activity removal is the removal of radionuclides from the waste using processes, such as sedimentation, evaporation, filtration or ion exchange. Removing the radioactive material will usually result in volume reduction.6.4 ConditioningFigure 8 Steps in conditioningConditioning of waste involves processes that transform radioactive waste into a form suitable for handling, transportation, storage and disposal. These include immobilization of radioactive waste, placing it in containers and providing additional packaging. In many cases treatment and conditioning take place in conjunction with one another.6.4.1 Immobilization It is important that radionuclides in stored or disposed waste are prevented from entering the environment. Immobilization is the process in which waste is converted to a solid product that will contain the radionuclides and minimize the chance of them entering the biosphere. The solid product is called a waste form.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 37 Module 3.4 - Safe Handling Of Radioactive WasteImmobilization includes solidification, embedding or encapsulating in cement or bitumen and vitrification into a glass matrix or synthetic rock.6.4.2 Packaging In order to make the waste form safe to handle, transport or store, it may be necessary to put treated waste into some sort of container. If one container does not provide enough protection or waste packages are to be consolidated, a second container, called an overpack, is used.SELF CHECK 6Now see how much you have understood by answering the following1. Incineration only reduces the volume of the waste, not the activity. Why is this important to know?2. Why would it be an advantage to incinerate combustible radioactive waste with large quantities of non-radioactive waste?3. Match the terms change of composition, conditioning, immobilization, pretreatment, radionuclide removal, treatment, and volume reduction with the following descriptions: a) Conversion of waste into a waste form by solidification, embedding or encapsulation. b) Processes intended to improve safety or economy by changing the physical or chemical characteristics of waste. c) Processes intended to transform waste into forms suitable for handling, transportation, storage and/or disposal. d) Evaporation, filtration or ion exchange of liquid waste streams. e) Processes that decrease the physical volume of the waste. f) Precipitation or flocculation of dissolved solids.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 38 Module 3.4 - Safe Handling Of Radioactive Waste g) Processes intended to prepare waste for treatment/reuse/disposal as exempt waste.4. Does radioactive waste have to follow all of the steps in a basic waste management program? Explain your answer.Now check your answers with the model answers in your workbook.7. CONTROLLING RADIOLOGICAL HAZARDSRadiological hazards exist at all stages of waste management, from the generation of waste through to the final disposal. You have studied methods of controlling radiological hazards in previous modules and the same techniques (e.g. time, distance, shielding, containment, etc) should be applied in handling waste. A waste processing facility must have a radiation protection program which addresses the following issues: Area and personal monitoring. Administrative control methods. Physical controls. Record keeping and reporting.An effective monitoring program should be set up to measure radiation and contamination (including airborne contamination) and the radiation protection program should include appropriate actions to be taken at the pre- determined monitoring levels.8. MONITORING LEVELS OF RADIOACTIVITY IN RADIOACTIVE WASTETo ensure radioactive waste is identified and treated correctly it is important that suitable monitoring systems are in place. These systems need to beProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 39 Module 3.4 - Safe Handling Of Radioactive Waste able to identify the radioisotopes which may be in the waste and determine the levels of activity.Monitoring is required in order to: Determine if the material is considered to be radioactive waste. Classify the waste and determine the disposal or discharge option. Provide data to show compliance with discharge licences or authorizations.In addition to monitoring waste, the Regulatory Authority may require the operator to collect and analyze samples from the vicinity of any radioactive discharge outlets. To ensure that radioactivity levels in the immediate environment are acceptable.8.1 Monitoring Methods Monitoring methods will be determined by the reason for the monitoring, the physical form of the waste and the radionuclides which may be present.Remember Instruments used for monitoring must be able to detect the types and energies of the radiation present.If monitoring is for the purpose of determining whether waste is exempt, then monitoring must be done very carefully and shielding within the waste must be taken into account. The minimum detectable level must be clearly identified and be less than the exempt level. For example, where bags of paper waste are monitored, the following could be carried out. Sealed radioactive sources of each isotope can be placed in the center ofGood idea bags of waste paper similar to those that would leave a laboratory. By taking measurements around the bag and comparing these to the source activities used, the limit of detection of the monitor for this type of wasteProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 40 Module 3.4 - Safe Handling Of Radioactive Waste can then be calculated. The limit of detection can them be examined to determine if it will meet the levels you are trying to measure.Waste that does not fit into the exempt category can be assayed using a drum scanner which uses several large scintillation detectors to count a drum of waste from all directions and can count over a long period if required. It will be necessary to sample the waste if alpha or low energy beta emitters are present, or if the drums offer too much shielding for low energy photons to be detected.8.2 Estimating The Activity Of Waste8.2.1 Solid waste The activity of radionuclides in solid waste may be determined from the drum scanning method described above. This is not always possible and it may be necessary to estimate the activity level by a process called ‘activity balance’. This is a way of determining where fractions of the total isotope activity went in the process and how much would have been discharged.Figure 9 Activity balances EXAMPLECarbon-14 compound paper waste which has been used to dry the tips of pipettes used in a radiochemical process. The stock solution was 100 MBq of an isotope and you were able to measure some of the places where the isotope may have gone.- 90MBq of the isotope was measured in the final product. (Counted using a liquid scintillation counter)Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 41 Module 3.4 - Safe Handling Of Radioactive Waste- 8MBq of the isotope was measured as liquid waste (including washing the pipettes) going down the sink.- 1.5MBq is estimated as being coated on the inside of the original stock bottle - The process generates no volatile or gaseous materials.Of the original 100MBq, you can account for 90 + 8 + 1.5 MBq = 99.5MBq.Therefore, the activity you cannot account for is 100 - 99.5 = 0.5MBq.You can assume that the paper waste contains 0.5MBq.In some cases, the measurements made might be very limited. Estimates of the generation of gases and contamination of items may need to be based on a knowledge of the process or from measurements taken on similar processes.8.2.2 Gaseous and liquid waste In situations where routine discharges are unlikely to exceed licence limits, “grab” samples can be taken of the waste stream at intervals agreed with the Regulatory Authority. This method is dependent on a numerical estimate of the total volume of gas or liquid discharged and an assumption that the rate of discharge is constant. The activity of the sample is measured and the value used to estimate total discharge.EXAMPLEA laboratory disposes of liquid radioactive waste for 12 hours a day into the site’s liquid effluent line. The lab is required to estimate its daily discharge of radioactive materials. A grab sample of 0.5 L of liquid effluent is taken and measured. The total activity of the radioisotope is 1kBq. The liquid effluent discharge line discharges 100L h-1 of liquid from the site.Step 1: Calculate the concentration of the total discharge.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 42 Module 3.4 - Safe Handling Of Radioactive WasteThe concentration of the radioactive material is1 kBq  2kBqL-1 0.5 LStep 2: Calculate the total volume of effluent discharged per day.12 hours per day x 100 Lh-1 = 1200 L per dayStep 3: Calculate the activity discharged per day.2 kBqL-1 x 1200 L per day = 2400 kBq per day= 2.4 MBq per dayIn some situations it may not be possible to measure the radioactive materials directly. In those situations an estimate of the activity would need to be made.Remember the methods of assessing the activity of materials for disposal must be approved by the Regulatory Authority.SELF CHECK 7Now see how much you have understood by answering the following1. Why is it necessary to monitor radioactive waste?2. List some important issues to consider when monitoring waste.3. How can the activity levels of solid waste be measured? What are some of the limitations of this method?4. When might grab samples be an acceptable way of monitoring waste?5. When monitoring solid waste, why might you use different types of monitors?Now check your answers with the model answers in your workbook.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 43 Module 3.4 - Safe Handling Of Radioactive Waste9. STORAGE OF RADIOACTIVE WASTEAlthough storage of radioactive materials is covered in Module 3.2 Transport and Storage, it is an important part of the waste management process, and some specific points must not be forgotten.In the sequence of radioactive waste management, storage is required to provide the following; Operational convenience (e.g. what to do with waste in the work place) Storage - Storage between various stages of waste processing (interim or temporary storage). Safe retention of conditioned waste containing longer lived activity pending the eventual establishment of disposal facilities.9.1 Operational Convenience Waste storage facilities for unprocessed waste will depend to some extent on the types of waste, the activity level and the half-life of the radionuclides involved. Storage in the workplace may range from simple stores with single secure cabinets to one or more dedicated rooms. It is important that careful waste segregation and good record keeping is maintained to allow efficient movement of waste for treatment or disposal. Segregation of waste in the work place (point of generation) is important for dose control in waste handling. Typically, waste is separated by type and sometimes, by isotope or half life.Common categories of waste are dry solid waste, liquid waste, sharps (includes broken glass and metal pieces – anything that may cause a cut or puncture wound) and biohazardous waste (canProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 44 Module 3.4 - Safe Handling Of Radioactive Waste include animal carcasses, animal bedding, animal waste, body fluids, tissue sample).Decay storage is usually applied to segregated low level waste from hospitals, universities and research laboratories for common shorter lived constituents such as Technetium-99m (6 hours), Iodine-131 (8 days) Iodine-125 (60 days) and Iridium-192 (74 days). As discussed earlier, a decay storage of ten half-lives will reduce the initial radioactivity down to 1/1000, which in many cases means below the limits for disposal, depending on the local regulatory practices. A planned system of collection and transfer of waste is required to prevent accumulation of waste in working areas which may lead to spread of contamination and unnecessary occupational dose exposure. Lined metallic or cardboard bins of less than 50 L capacity are commonly used as workplace receptacles for combustible- compactable waste. Refuse bins with foot operated lids are particularly useful for radioisotope laboratories. Combustible waste should not be allowed to build up in work places. Bins for active waste should be clearly marked to distinguish them from bins meant for inactive waste.  Sharps that are used in medical procedures, radiopharmaceutical production and research using radioactive materials, such as needles, syringes, scalpels and intravenous tubing, are often considered biohazardous waste as well as radioactive. Metal cans are considered the best choice for metal pieces and broken glass (if sharps containers are unavailable) as they can beProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 45 Module 3.4 - Safe Handling Of Radioactive Waste sealed and disposed of without further risk to those handling the waste. At radioisotope production facilities quantities of solid and liquid waste at intermediate activity levels can be produced. These will require local decay storage of the short lived contaminants in carefully designed storage arrangements adjacent to or in hot cells. Solids waste arising from production of Molybdenum -99, Iodine- 125 and –131, such as contaminated spent cans and extraction columns, require some months of shielded storage prior to release for further treatment. Liquid waste should be stored in shielded containment flasks while awaiting processing.9.2 Storage The design of a storage facility to allow the decay of short lived radioactive material or while waiting to transport the waste to a repository, will depend on the amount and activity of the waste.Stores suitable for this type of waste can be as simple as a barriered area (provided it is secure) or a locked cupboard for small quantities. For larger quantities of waste, or where the dose rate requires the waste to be shielded or segregated, a purpose built room or building should be used.The general design features of these stores should comply with appropriate safety and good housekeeping requirements, including the following; Containers and stores holding radioactive waste must be labeled to warn people of the presence of radioactive materials. Store design should always provide security from unauthorized entry. Stores for radioactive material should be away from working areas and designed so that all persons are adequately protected during both storage and transfer of material to and from the store.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 46 Module 3.4 - Safe Handling Of Radioactive Waste Shielding should be provided so that radiation doses at any accessible position outside the store do not exceed the levels specified by the Regulatory Authority. These levels are usually set at a value that ensures people in the vicinity of the store will not exceed dose limits or dose constraints. These levels will vary depending on the location of the store and the occupancy of the area. Shielding should take account of scattered radiation and source distribution. Advantage should be taken of self-shielding, e.g. by arranging spent sources so that the highest activity is at the center. Storage of waste should be tidy and depending on the amount of material placed in drums, racks, pallets or skids suitably planned for minimum handling. Adequate storage capacity should be provided to allow good housekeeping and avoid waste storage in working areas. Material storage must be designed to ensure smoke detection and sprinklers and drains are not obstructed. There should be fire fighting provisions and adequate clearance below sprinkler heads. Appropriate ventilation should be included in the design, particularly if waste include volatile or gaseous radionuclides e.g. Tritium, Carbon-14, Iodine-131 or gas producing nuclides such as radium or thorium. Store design should take account of risks resulting from natural sources such as flood or gales. Stores should take into account non-radiological hazards of the waste. For example, the radioactive component of the waste may have decayed, but a chemical or biohazardous property may still remain. Some countries do not have repositories established, so waste must be put into storage to await future disposal. These storageProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 47 Module 3.4 - Safe Handling Of Radioactive Waste facilities should include multiple engineered or natural barriers to prevent the migration of radioactive waste. These barriers incorporate concrete or clay lined pits for the burial of drums of radioactive waste. In addition to the normal radiological precautions such as security, contamination and dose rate controls, storing for longer time intervals has potential problems such as leaching by ground water and seismic conditions, that should be considered. This sort of store includes the use of geological disposal sites. These type of facilities are a specialized area and not part of this module.10. RECORDSAccurate record keeping is an important part of the control of all radioactive materials. It is important that the presence and subsequent treatment and/or disposal of radioactive waste is recorded. This will ensure the waste can be controlled and reduces the possibility of causing uncontrolled exposure in the environment.Records are required for the following types of waste: Exempt waste. Waste at various stages of processing. Waste in storage awaiting disposal. Liquid and airborne discharges. Waste sent to a disposal facility.Each type of record should contain the following information. Identification/Record number. Description of waste.  Nuclide identification and total activity.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 48 Module 3.4 - Safe Handling Of Radioactive Waste Activity concentration (in Bq g-1 or Bq m-3). Location (if in store). Disposal route. Disposal authorization. Disposal date.The format and retention of these records will be determined by the national requirements and will form a part of a quality assurance system.SELF CHECK 8Now see how much you have understood by answering the following.1. What 3 reasons would there be for storing radioactive waste?2. How should the following items be stored in the work place?(a) Paper and gloves contaminated with Co-60.(b) Syringes contaminated with I-131.(c) Liquid waste containing fission products.3. When waste is stored to decay how many half lives are normally used as the storage time?What fraction of the original does this number of half lives give?4. Will this number of half lives always be enough to allow release of the waste? Give a reason for your answer and if possible suggest an example5. List (briefly) the requirements for a store for waste which is awaiting disposal.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 49 Module 3.4 - Safe Handling Of Radioactive Waste6. What pieces of information would you expect to be the minimum detailed in a record of the disposal of radioactive waste?Now check your answers with the model answers in your workbook.KEY POINTS The definition of radioactive waste for regulatory purposes is material for which no further use is foreseen, that contains, or is contaminated with, radionuclide concentrations or activities greater than the clearance levels as established by a regulatory body. The internationally agreed objective of radioactive waste management is to deal with radioactive waste in a manner that protects human health and the environment now and in the future, without imposing undue burdens on future generations.  A good waste management programme minimizes the amount of radioactive waste generated, thus minimizing the hazard and maximizing the use of space in disposal facilities. The international classes of waste are exempt waste, low intermediate level waste and high level waste. Exempt waste (EW) is defined as waste that is excluded from regulatory control because its radiological hazards are negligible, i.e. its activity concentration and/or total activity are below clearance levels established by a country’s Regulatory Authority. Low intermediate level waste (LILW) is further divided into 2 categories - short lived waste (LILW-SL) and long lived waste (LILW-LL).  Short lived waste is waste containing radionuclides having a half life less than 30 years.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 50 Module 3.4 - Safe Handling Of Radioactive Waste Long lived waste is waste containing long lived (T1/2 > 30 years) radionuclides having sufficient radiotoxicity in quantities and/or concentrations requiring long term isolation from the biosphere. High level waste (HLW) is waste that is sufficiently radioactive to require both shielding and cooling. High level waste has concentrations of long lived radionuclides which exceed the limits for LILW-LL and the radioactive decay process produces heat at a rate above about 2kWm-3. Liquid/gaseous waste may be discharged directly into the environment (typically through the water system or directly into the air), providing the levels are low. Solid waste is typically treated and either reused, considered exempt or disposed of accordingly. The IAEA plays an advisory role in radioactive waste management. A national framework for waste management is necessary to protect that country’s citizens (and those in surrounding countries) from unnecessary exposure to radioactive materials.  It is important to process radioactive waste so it can be stored or disposed of in a form that poses little or no threat to the biosphere. Processing waste involves pretreatment, treatment and conditioning.  Pretreatment is any or all of the operations prior to waste treatment, such as collection, segregation, chemical adjustment and decontamination. Treatment is any operation intended to benefit safety and/or economy by changing the characteristics of the waste. Three basic treatment methods are volume reduction, removal of radionuclides from the waste and change of composition.  Conditioning is defined as the operations that produce a waste package suitable for handling, transportation, storage and/or disposal. Conditioning may include the conversion of radioactive waste to a solidProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 51 Module 3.4 - Safe Handling Of Radioactive Waste waste form (immobilization), enclosure of the radioactive waste in containers (packaging) and, if necessary, providing an overpack. Radiological hazards must be controlled in all stages of waste management. External radiation hazards are controlled by time, distance and shielding techniques. Containment is essential when waste material is an unsealed source. An effective personnel and area monitoring system must be established. Waste must be monitored in order to identify exempt waste, determine appropriate treatment and to demonstrate compliance with licences and authorizations. Instruments and monitoring methods for waste monitoring must be appropriate for the task. Storage at all stages of waste management must provide safety, by minimizing radiological hazards and security. Record keeping is an important component of waste management. The characteristics to be recorded for radioactive waste are Identification/Record number, description of waste, nuclide identification and total activity, activity concentration (in Bq g-1 or Bq m-3), location, disposal route, disposal authorization and disposal date.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 52 Module 3.4 - Safe Handling Of Radioactive WasteAPPENDIX 1Table 6 Waste classes and recommended disposal options. Waste classes. Typical Characteristics. Disposal options. 1. Exempt Waste (EW) Activity levels at or below No radiological clearance levels given in restrictions. BSS No.115 which are based on an annual dose to the public of less than 0.01mSv. 2. Low and Intermediate Activity level above level waste (LILW) clearance levels given in BSS No.115 and thermal power below 2kWm-3. 2.1 Short lived waste Restricted long lived Near surface or (LILW-SL). radionuclide concentrations geological disposal (limitation of long lived alpha facility. emitting radionuclides to 4000 Bq g-1 in individual waste packages and to an overall average of 4000 Bq g- 1 per waste package.)2.2 Long lived waste Long lived radionuclide Geological disposal (LILW-LL). concentrations exceeding facility. limitations for short lived waste. 3. High level waste Thermal power above 2 Geological disposal (HLW) kWm-3 and long lived facility. radionuclide concentrations exceeding limitations for short lived waste.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 53 Module 3.4 - Safe Handling Of Radioactive WasteTable 7 Default values of habit and other data for external exposure, inhalation and ingestion dose estimation for a critical group in Europe.*Infant Adult Type of Exposure Occupancy Intake per Occupancy Intake per fraction person fraction person External exposure Surface contaminated 1 - 1 - owing to air deposition Working/playing over 0.18 - 0.12 - contaminated sediments Submersion in air 1 - 1 - Inhalation - 8400 - 1400 Breathing rate (m3 per year) Ingestion Water and beverages - 0.600 - 0.260 (m3 per year)*Excerpt data from Table XIV, IAEA Safety Reports Series No. 19, “Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substances to the Environment.”Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 54 Module 3.4 - Safe Handling Of Radioactive WasteAPPENDIX 2DISCHARGE LIMIT CALCULATIONSIn order to calculate discharge limits, it is necessary to: Choose a model for your situation/screening calculations. Consider the most significant exposure pathway.The following examples for liquid waste and for gaseous waste show you how to calculate discharge limits in a simple way. Remember that here we have simplified the process in order to help you understand it.LIQUID WASTE EXAMPLEDischarge to river. River is the only source of drinking water for the critical group. No Model further dilution. River is not used for crop irrigation.Significant exposure pathways Ingestion – direct drinking of water.Critical group Infants from Table 3Data Lab discharge rate = 10 000 m3 per week. River flow rate = 100 000 m3 per week. Dose conversion factor (infants) = 6.4 x 10-11 Sv Bq-1. Annual intake (infants) = 0.260 m3 Dose constraint 0.1 mSvDischarge limit Can be calculated from above data (see Appendix 2).Question:Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 55 Module 3.4 - Safe Handling Of Radioactive WasteA laboratory wants to discharge tritiated water into a local river. The river passes a water treatment plant where the water is taken, treated (with no further dilution) and supplied to the local town as drinking water. The laboratory must provide information about the proposed discharge to the Regulatory Authority who will then check the details and the projected doses to the public and any potentially exposed worker, prior to issuing an authorization and setting a limit on the discharge.The tritiated water is disposed of through a sink drain into the site effluent, which has a discharge rate to the river of 10 000 m3 per week.Calculate the average weekly discharge activity limit.Information: For tritiated water, the most significant pathway into the body is via ingestion.The default annual intake of drinking water for an adult member of the public is 600 L (or 0.6 m3).The dose conversion factor for ingestion of tritiated water is 1.8x10-11 Sv Bq-1.The river has a flow rate of 100 000 m3 per week. (An approximate estimate could be made from the physical dimensions of the river and the linear flow rate.)Assumptions: Assume that the dose constraint for a member of public has been set by the Regulatory Authority as 0.1 mSv y-1 from liquid discharges. Method:Step 1: Let the maximum activity released per year be A Bq y-1.Step 2: Calculate the volume of water (including the discharge) passing through a point of interest per year (m3 y-1).Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 56 Module 3.4 - Safe Handling Of Radioactive WasteThe volume of water passing a given point in a year represents the effective annual dilution of the radioactive material. The annual dilution is:52 weeks per year x (10 000 + 100 000) m3 = 5.72 x106 m3= 5 x106 m3In order to provide a conservative estimate, the annual dilution is rounded down to 5 x106 m3 instead of rounded up to 6 x106 m3. Step 3: Find A, substituting the appropriate dose constraint.For a dose of 0.1 mSv y-1 (or 0.1 x 10-3 Sv y-1):A n n u a l W a t e r I n t a k e x D o s e C o n v e r s i o n F a c t o r x M a x i m u m A n n u a l A c t i v i t y R e l e a s e d D o s e c o n s t r a i n t  T o t a l V o l u m e D i s c h a r g e d p e r y e a r0 . 6 x 1 . 8 x 1 0 - 1 1 x A 0.1 x 10-3 = 5 x 1 0 60.1 x 10-3 = (2.16 x 10–18 x A)0 . 1 x 1 0 - 3 So A = 2 . 1 6 x 1 0 - 1 8= 4.6x 1013= 46 x 1012 Bq= 46 TBqStep 4: Calculate the average weekly discharge limit.The limit for the weekly discharge for tritiated water would be:4 6 x 1 0 1 2  8 . 9 0 x 1 0 1 1  8 9 0 G B q p e r w e e k 5 2Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 57 Module 3.4 - Safe Handling Of Radioactive WasteConclusion:Therefore, the lab can discharge an average weekly activity of 890 GBq of tritiated water into the river without exposing an adult member of the public to an annual dose over the dose constraint imposed by the Regulatory Authority.GASEOUS WASTE EXAMPLEDischarge to river. River is the only source of drinking water for the critical group. No Model further dilution. River is not used for crop irrigation.Significant exposure pathways Ingestion – direct drinking of water.Critical group #### from Table 3Data Lab discharge rate = 10 000 m3 per week.River flow rate = 100 000 m3 per week.Dose conversion factor (critical group) = Sv Bq-1. Annual intake (critical group) = m3 Dose constraint 0.1 mSvDischarge limit Can be calculated from above data (see Appendix 2).Question:A radioisotope production plant is seeking authority to discharge gaseous Iodine-131 from its stack. Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 58 Module 3.4 - Safe Handling Of Radioactive WasteThe plant must provide information about the proposed discharge to the Regulatory Authority who will then check the details, prior to issuing an authorization and setting a limit on the discharge.Calculate the weekly discharge activity limit for gaseous I-131. Information:The stack is 60m tall and the cross-sectional area of the stack at the point of release is 0.7 m2.The velocity of the discharge is 15 ms-1.Let the fraction of the time the wind blows towards the point of interest be Pp. A value of 0.25 (dimensionless) is suggested for this calculation. This is equivalent to an occupancy factor.To determine the critical group for an inhalation calculation, multiply the dose conversion factor for inhalation with the inhalation rate. The critical group is indicated by the highest product. Table 3 shows how to determine the critical group.Table 8 Determination of Critical Group Age Group. Dose conversion Inhalation rate. Product of dose factor, inhalation. factor and (m3 day-1) inhalation rate*. (Sv Bq-1) infant (1y) 7.2 x 10-8 5.16 3.7 x 10-7 child (10y) 1.9 x 10-8 15.3 2.9 x 10-7 adult (male*) 7.4 x 10-9 22.2 1.6 x 10-7*Note: The units of the product are meaningless, so they are not included.From Table 5, infants are the critical group.The dose conversion factor for an infant for inhalation of I-131 is 7.2 x 10-8 Sv Bq-1. (IAEA BSS No.115)Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 59 Module 3.4 - Safe Handling Of Radioactive WasteThe external dose conversion factor for immersion in gaseous Iodine-131 is 5.8 x 10-7 Sv year-1 per Bq m-3. (Safety Report Series No. 19)The daily breathing rate for an infant is 5.16 m3 per day. (ICRP 71)Assumptions:1. Assume that the dose constraint for a member of public has been set by the Regulatory Authority as 0.1 mSv y-1 for gaseous discharges from this facility.2. A worst case scenario, or screening calculation, assumes that the concentration of the radionuclide at the point of interest (where the critical group is) is the same as that at the point of release. Method:Starting point: We are calculating the average weekly discharge limit in Bq per week. We will need to find the maximum activity released per year which would be equivalent to a dose of 0.1 mSv to the critical group.Let the maximum activity released per year be A Bq y-1.Step 1: Calculate the annual breathing rate for a 1 year old infant.Daily breathing rate = 5.16 m3/dayAnnual breathing rate = 5.16 m3/day x 365 day/year= 1883 m3/yearStep 2: Calculate the volumetric air flow rate, V (m3s-1), from the stack.V = Air velocity x Cross-sectional area of the stack= 15 ms-1 x 0.7 m2= 10.5 m3s-1Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 60 Module 3.4 - Safe Handling Of Radioactive WasteStep 3: Calculate the volume (m3) of air coming from the stack in one year.10.5 m3s-1 x 60 sec x 60 min x 24 hours x 365 days = 3.3 x 108 m3 y-1Step 4: Calculate each pathway separately:Because the 0.1 mSv dose constraint is the sum of potential doses from all exposure pathways, we need to consider the contribution from each pathway in our calculation.− Contribution due to inhalation of I-131:Pp x DFinh x Rinh Where Pp = the fraction of the time the wind blows towards the point of interest (dimensionless). A value of 0.25 is suggested for this level of calculation.-1 DFinh = dose conversion factor for inhalation (Sv Bq )3 -1 Rinh = inhalation rate (m y )-8 Pp x DFing x Rinh = 0.25 x 7.2 x 10 x 1883= 3.39 x 10-5 Sv Bq-1m3 y-1 i.e. The dose per year per unit concentration is 3.39 x 10-5 Sv.− Contribution due to ingestion of I-131:Pp x DFing x Hing Where Pp = the fraction of the time the wind blows towards the point of interest (dimensionless). A value of 0.25 is suggested for this level of calculation.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 61 Module 3.4 - Safe Handling Of Radioactive Waste-1 DFing = dose conversion factor for ingestion (Sv Bq )-1 Hing = rate of consumption (kg y )For this example, we are assuming that the critical group is standing at the point of discharge for screening purposes. The ingestion pathway will be of much lower significance by comparison. If more detailed analysis is needed, then information such as diet, agricultural areas, livestock, irrigation methods and rainfall is required.− Contribution due to immersion in a cloud of I- 131:Pp x DFimm Where Pp = the fraction of the time the wind blows towards the point of interest (dimensionless). A value of 0.25 is suggested for this level of calculation.DFimm = dose conversion factor for immersion (Sv y-1 per Bqm-3)-7 Pp x DFimm = 0.25 x 5.8 x 10= 1.45 x 10-7 Sv y-1 per Bqm-3 i.e. The dose per year per unit concentration is 1.45 x 10-7 Sv.From the numerical values of the pathway contributions, it can be seen that the contribution due to immersion in the discharge is significantly less than that of the contribution due to inhalation. It would be acceptable to consider the inhalation pathway only in this screening example.Step 5: Find A, substituting the appropriate dose constraint.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 62 Module 3.4 - Safe Handling Of Radioactive Waste S u m o f t h e D o s e p e r y e a r   A c t i v i t y C o n c e n t r a t i o n  T o t a l a n n u a l d o s e    x    p e r u n i t c o n c e n t r a t i o n   i n E f f l u e n t S u m o f t h e P a t h w a y C o n t r i b u t i o n s x A n n u a l A c t i v i t y D i s c h a r g e d T o t a l a n n u a l d o s e  T o t a l V o l u m e D i s c h a r g e d p e r y e a rA   P D F H  P D F R  P D F  x p i n g i n g p i n h i n h p i m m V where : A = maximum activity (Bq)V = volumetric air flow rate (m3 y-1)Remember that the units of the right hand side of the equation include Sv, ! therefore convert the dose constraint from mSv to Sv before substitution.So:3 . 3 9 x 1 0 - 5 x A 0 . 1 x 1 0 - 3  3 . 3 x 1 0 80.1 x 10-3 = 1.03 x 10-13 AA = 9.73 x 108 Bq= 0.973 GBqStep 6: Calculate the average weekly discharge limit.So the average weekly discharge activity limit is: 0.973 GBq  52 weeks = 18.7 MBq per week.Conclusion:Therefore in this simple scenario, an average weekly discharge activity of 18.7 MBq of gaseous I-131 would cause an exposure of 0.1 mSv per year to an infant. Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 63 Module 3.4 - Safe Handling Of Radioactive WasteNote that this example is assuming that the plant is discharging Iodine-131 ONLY. In reality, you will encounter discharges that have more than one radionuclide present and the limit that is imposed by the Regulatory Authority will include ALL radionuclides and ALL pathways contributing to dose.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 64 Module 3.4 - Safe Handling Of Radioactive WasteAPPENDIX 3DOSE LIMIT CALCULATIONSExamples of how a dose estimate calculation for a given effluent discharge is carried out is given below.LIQUID WASTE EXAMPLEQuestion:Ruthenium-106 is being released into a river at the rate of 4.5 x 1010 Bq per year. The discharge rate is 1 m3s-1. The flow rate of the river is 8 m3s-1.Calculate the potential dose received by an adult and an infant living on a farm nearby, who draw their water for drinking from the river.Information:The dose conversion factor for ingestion of Ru-106 for an adult is 7.0 x 10 -9 Sv Bq-1. The dose conversion factor for ingestion of Ru-106 for an infant is 4.9 x 10 -8 Sv Bq-1.The default annual water intake for an adult is 0.6 m3 y-1.The default annual water intake for an infant is 0.26 m3 y-1.Assumptions:Assume that the ingestion pathway is the most likely pathway contributing to the dose. We are also assuming that the ingestion pathway is only via the ingestion of water. Other methods of ingestion (e.g. via plant uptake) might need to be considered if more analysis is required.Method:Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 65 Module 3.4 - Safe Handling Of Radioactive Waste-3 Step 1: Calculate the concentration of radionuclide in the water, Cw (Bq m ).Note that it is important to be consistent with the units of time in this calculation. So if you choose to work in Bq y-1, then make sure that the discharge rate is converted to m3 y-1. Since the time unit for the discharge rates is seconds, we would need to convert the activity from Bq y-1 to Bq s-1.4 . 5 x 1 0 1 0 4.5 x 1010 Bq y-1  3 6 5 d a y s x 2 4 h o u r s x 6 0 m i n u t e s x 6 0 s e c o n d s4 . 5 x 1 0 1 0 = 3 1 . 5 x 1 0 6= 1429 Bq s-1So,A c t i v i t y r a t e R a d i o n u c l i d e C o n c e n t r a t i o n , C  w T o t a l V o l u m e o f F l u i d p a s s i n g p o i n t o f i n t e r e s t1 4 2 9 B q s - 1 = ( 1  8 ) m 3 s - 1= 158.8 Bq m-3Step 2: Calculate the dose from ingestion for the adult and infant.Annual effective dose from ingestion of radioactive water, Eing (Sv per year), is: Eing = CwDFingHw where Cw = the annual average concentration of nuclide i in water (Bq m-3) (i in this example is Ru-106.)-1 DFing = the dose coefficient for ingestion of radionuclide i (Sv Bq )Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 66 Module 3.4 - Safe Handling Of Radioactive Waste3 Hw = the consumption rate of drinking water (m per year).− The dose to the adult from Ru-106 is:Eing = CwDFingHw= 158.8 x 7.0 x 10-9 x 0.6= 6.67 x 10-7 Sv y-1= 0.67 Sv y-1− The dose to the infant is:Eing = CwDFingHw= 158.8 x 4.9 x 10-8 x 0.26= 2.02 x 10-6 Sv y-1= 2.02 Sv y-1* Note that if there was more than one radionuclide being released into the river, this calculation would have to be done for each radionuclide, and the doses added together for a total dose.Conclusion:Therefore, the potential dose from this discharge is 0.67 Sv y-1 for an adult and 2.02 Sv y-1 for an infant.GASEOUS WASTE EXAMPLEQuestion:Iodine-131 is released at a rate of 1 Bq s-1 over an entire year from a 60m stack. What is the potential dose to an infant and an adult living on a farm nearby?Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 67 Module 3.4 - Safe Handling Of Radioactive WasteInformation:The air velocity at the point of discharge is 12 ms -1 and the cross-sectional area of the stack is 1 m2.The external dose conversion factor for immersion in gaseous Iodine-131 is 5.8 x 10-7 Sv year-1 per Bqm-3. (Safety Series Report No. 19)The dose conversion factor for inhalation of Iodine-131 for an adult is 7.4 x 10-9 Sv Bq-1. (IAEA BSS No. 115)The dose conversion factor for inhalation of Iodine-131 for an infant is 7.2 x 10-8 Sv Bq-1. (IAEA BSS No. 115)The default annual breathing rate for an adult is 8400 m 3 y-1. (Safety Series Report No. 19)The default annual breathing rate for an infant is 1400 m 3 y-1. (Safety Series Report No. 19)Assumptions: Occupancy factor (Of) = 1.0 (from Table XIV IAEA Safety Reports Series No. 19) The fraction of time the wind blows towards the point of interest (Pp) = 0.25 There is no dilution or mixing of the plume.Method:Step 1: Calculate the volumetric air flow rate (V, in cubic metres per second) from the stack at the point of discharge.V = Air velocity x Cross-sectional area of the stack= 12 ms-1 x 1 m2Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 68 Module 3.4 - Safe Handling Of Radioactive Waste= 12 m3s-1Step 2: Calculate the concentration of radionuclides in the air, CA, using:P Q C  p i A V-3 where CA = ground level air concentration at downwind distance x (Bq m ).Pp = the fraction of the time the wind blows towards the point of interest (dimensionless). A value of 0.25 is suggested for this level of calculation.-1 Qi = the average discharge rate of the radionuclide i (Bq s ). (i in this example is I-131.)V = the volumetric air flow rate of the vent or stack at the point of release (m3s-1).If there was more than one radionuclide being released from the stack, this calculation would have to be done for each radionuclide, and the doses added together for a total dose. This example states only I-131 is being released, and therefore, only one set of calculations need to be carried out.0 . 2 5 x 1 C  A 1 2= 20.8 x 10-3 Bq m-3Step 3: Calculate the external dose from immersion in the plume, from I-131.Annual effective dose from immersion in the atmospheric discharge plume,Eim (Sv per year), is: Eim = CADFimOf-3 where CA = the annual average concentration of nuclide in air (Bq m ).Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 69 Module 3.4 - Safe Handling Of Radioactive WasteDFim = the effective dose coefficient for immersion (Sv per year per Bq m-1).Of = the fraction of the year the critical group member is exposed to this particular pathway. So,Eimm = CADFimmOf= 20.8 x 10-3 x 5.8 x 10-7 x 1.0= 1.2 x 10-8 Sv y-1= 0.012 Sv y-1Step 3: Calculate the dose from inhalation.Annual effective dose from immersion in the atmospheric discharge plume,Einh (Sv per year), is: Einh = CADFinhRinh-3 where CA = the annual average concentration of nuclide in air (Bqm )-1 DFinh = the inhalation dose coefficient (Sv per year per Bqm )3 Rinh = the inhalation rate (m per year).− The dose to the adult is:Einh = CADFinhRinh= 20.8 x 10-3 x 7.4 x 10-9 x 8400= 1.295 x 10-6 Sv y-1= 1.3 Sv y-1− The dose to the infant is:Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 70 Module 3.4 - Safe Handling Of Radioactive WasteEinh = CADFinhRinh= 20.8 x 10-3 x 7.2 x 10-8 x 1400= 2.1 x 10-6 Sv y-1= 2.1 Sv y-1Step 4: The total dose is the addition of all internal and external doses.Etotal = Eimm + EinhEtotal(adult) = Eimm + Einh= (0.012 + 1.3) Sv y-1 1.3 Sv y-1Etotal(infant) = Eimm + Einh= (0.012 + 2.1) Sv y-1 2.1 Sv y-1Conclusion:Therefore, the potential dose from this discharge is 1.3 Sv y-1 for an adult and 2.1 Sv y-1 for an infant.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 71 Module 3.4 - Safe Handling Of Radioactive WasteGLOSSARYBiosphere That part of the environment normally inhabited by living organisms.Clearance level A value, established by the regulatory body in a country or state, expressed in terms of activity concentrations and/or total activities, at or below which sources of radiation can be released from regulatory control.Conditioning Those operations that produce a waste package suitable for handling, transportation, storage and/or disposal. Conditioning may include the conversion of radioactive waste to a solid waste form, enclosure of the radioactive waste in containers and, if necessary, providing an overpack.Critical groups A group of members of the public which is reasonably homogenous with respect to its exposure or potential exposure from a given source and given exposure pathway and is typical of individuals receiving the highest dose or risk by the given exposure pathway from the given source. The relevant dose is normally effective dose or equivalent dose.Disposal The placement of waste in an approved, specified facility (e.g. near surface or geological repository) without the intention of retrieval. Disposal also covers the approved direct discharge of effluents (e.g. liquid and gaseous wastes) into the environment, with subsequent dispersion.Dose constraint A prospective and source related restriction on the individual dose delivered by the source which serves as a bound in the optimization of protection and safety of the source. Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 72 Module 3.4 - Safe Handling Of Radioactive WasteEffluent Gaseous or liquid radioactive materials which are discharged into the environment.Exempt waste In the context of radioactive waste management, waste that is released from nuclear regulatory control in accordance with clearance levels, because the associated radiological hazards are negligible. The designation should be in terms of activity concentration and/or total activity and may include a specification of the type, chemical/physical form, mass or volume of waste.Exemption level A value, established by a regulatory body and expressed in terms of activity concentration and/or total activity, at or below which a source of radiation may be granted exemption from regulatory control without further consideration.Flocculation The joining together of a finely divided precipitate into larger particles.Geological Isolation of waste, using a system of engineered and disposal natural barriers at a depth several hundred metres in a geologically stable formation. Typical plans call for disposal of long lived and high level waste in geological formations.Immobilization Conversion of waste into a waste form by solidification, embedding or encapsulation. Immobilization reduces the potential for migration or dispersion of radionuclides during handling, transport, storage and/or disposal.Infant In dosimetry, unless otherwise stated, an infant is assumed to be a one-year-old, and annual quantities (e.g. annual dose, annual intake) relating to an infant refer to the year starting at birth.Ion exchange A reversible chemical reaction between an insolubleProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 73 Module 3.4 - Safe Handling Of Radioactive Waste solid and a solution during which ions may be interchanged.Liquid waste Radioactive waste in liquid form which may contain dissolved, colloidal or dispersed solids. Long lived waste Radioactive waste containing long lived radionuclides having sufficient radiotoxicity in quantities and/or concentrations requiring long term isolation from the biosphere. The term ‘long lived radionuclide’ usually refers to half lives greater than 30 years.Near surface A facility for radioactive waste disposal located at or repository within a few tens of metres of the Earth’s surface.Overpack A secondary (or additional) outer container for one or more waste packages for handling, transport, storage and/or disposal.Packaging Preparation of radioactive waste for safe handling, transport, storage and/or disposal by means of enclosing it in a suitable container.Predisposal Any waste management steps carried out prior to disposal, such as pretreatment, treatment, conditioning, storage and transport activities. Predisposal is used as a contraction of ‘predisposal radioactive waste management’, not a form of disposal.Pretreatment Any or all of the operations prior to waste treatment, such as collection, segregation, chemical adjustment and decontamination.Processing Any operation that changes the characteristics of waste, including pretreatment, treatment and conditioning.Radioactive waste For legal and regulatory purpose, radioactive waste may be defined as material that contains or isProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 74 Module 3.4 - Safe Handling Of Radioactive Waste contaminated with radionuclides at concentrations or radioactivity levels greater than ‘exempt quantities’ established by the competent regulatory authorities and for which no further use is foreseen.Radioactive waste All activities, administrative and operational, that are management involved in the handling, pretreatment, treatment, conditioning, transportation, storage and disposal of waste from a nuclear facility.Repository A nuclear facility where radioactive waste is placed for disposal. Future retrieval of waste from a repository is not intended.Sedimentation The act of causing the deposit of sediment, especially by the use of a centrifuge.Segregation An activity where waste or materials (radioactive and exempt) are separated or kept separate according to radiological, chemical and/or physical properties which will facilitate waste handling and/or processing. It may be possible to segregate radioactive from exempt material and thus reduce the waste volume.Short lived waste Radioactive waste which will decay to a level which is considered to be insignificant, from a radiological viewpoint, in a time period during which institutional control can be expected to last. Radionuclides in short lived waste will generally have half lives less than 30 years.Storage The placing of waste in a nuclear facility where isolation, environmental protection and human control (e.g. monitoring) are provided and with the intent that the waste will be retrieved for exemption or processing and/or disposal at a later time.Treatment Operations intended to benefit safety and/or economy by changing the characteristics of the waste. ThreeProduction D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 75 Module 3.4 - Safe Handling Of Radioactive Waste basic treatment objectives are:  volume reduction  removal of radionuclides from the waste  change of composition. Volume reduction A treatment method that decreases the physical volume of a waste. Typical volume reduction methods are mechanical compaction, incineration and evaporation. Volume reduction should not be confused with waste minimization.Waste form Waste in its physical and chemical form after treatment and/or conditioning (resulting in a solid product) prior to packaging. The waste form is a component of the waste package.Waste package The product of conditioning that includes the waste form and any container(s) and internal barriers (e.g. absorbing materials and liner), as prepared in accordance with requirements for handling, transportation, storage and/or disposal.Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018 Radiation Protection Distance Learning Project Page 76 Module 3.4 - Safe Handling Of Radioactive WasteREFERENCES:IAEA Safety Standards Series No. 111-F, “The Principles of Radioactive Waste Management.”IAEA Safety Standards Series No. 111-S-1, “Establishing a National System for Radioactive Waste Management.”IAEA Safety Standards Series No. 111-G-1.1, “Classification of Radioactive Waste.”IAEA Safety Reports Series No. 19, “Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substances to the Environment.”ICRP Publication 71, “Age-dependent Doses to Members of the Public from Intake of Radionuclides: Part 4 Inhalation Dose Coefficients.”IAEA Safety Standards Series No. WS-G-2.3, “Regulatory Control Of Radioactive Discharges Into The Environment.”Production D:\Docs\2018-04-07\0daa02379449be8551bdc1180bf7020c.doc Printed: 4/30/2018

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