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Radiation safety: New international standards

The forthcoming International Basic Safety Standards for Protection Against Ionizing and for the Safety of Radiation Sources are the product of unprecedented co-operation by Abel J. B*y the end of the 1980s, a vast amount of new This article highlights an important result of Gonzalez information had accumulated to prompt a new this work for the international harmonization of look at the standards governing protection radiation safety: specifically, it presents an over- against exposures to and the view of the forthcoming International Basic safety of radiation sources. Safety Standards for Protection Against Ionizing First and foremost, a re-evaluation of the Radiation and for the Safety of Radiation Sour- radioepidemiological findings from Hiroshima ces — the so-called BSS. They have been jointly and Nagasaki suggested that exposure to low- developed by six organizations — the Food and level radiation was riskier than previously es- Agriculture Organization of the United Nations timated. (FAO), the International Atomic Energy Agency Other developments — notably the nuclear (IAEA), the International Labour Organization accidents at Three Mile Island in 1979 and at (ILO), the Nuclear Energy Agency of the Or- in 1986 with its unprecedented ganization for Economic Co-operation and transboundary — had a great ef- Development (NEA/OECD), the Pan American fect on the public perception of the potential Health Organization (PAHO), and the World danger from . Accidents with Health Organization (WHO). radiation sources used in medicine and industry also have attracted widespread public attention: Cuidad Juarez (Mexico), Mohamadia (Moroc- The framework for harmonization co), Goiania (Brazil), San Salvador (El Sal- vador), and Zaragoza (Spain) are names that ap- In 1991, within the framework of the Inter- peared in the news after people were injured in agency Committee on Radiation Safety, the six radiation accidents. Furthermore, the decade saw organizations created a Joint Secretariat under the rediscovery of natural radiation as a cause of the co-ordination of the IAEA. The action concern for health: some dwellings were found capped decades of continuing efforts and marked to have surprisingly high levels of in air; an unprecedented international co-operation that natural radiation exposures of some non-radia- has involved hundreds of experts from the Mem- tion-related workers were discovered to be at ber States of the sponsoring organizations for levels much higher than the occupational limits establishing the BSS. These international stand- specified in recognized standards. ards supersede any previous ones in the field of Following these developments, the Interna- radiation safety, in particular those developed tional Commission on Radiological Protection under the auspices of the IAEA. (See box, next (ICRP) in 1990 revised its standing recommen- page.) dations. The concerned organizations of the Radiation effects. From the time of early United Nations family and other multinational studies on X-rays and radioactive minerals it was agencies promptly followed by triggering a recognized that exposure to high levels of radia- review of their own standards. tion can harm exposed tissues of the human body. These radiation effects can be clinically diagnosed in the exposed individual; they are called deterministic effects because, given a Dr Gonzalez is Deputy Director of the IAEA Division of radiation dose, they are determined to occur. Nuclear Safety. Posteriorly, long-term studies of populations ex-

IAEA BULLETIN, 2/1994 FEATURES

A number of bodies have supported the United Nations Scientific Committee on International work to harmonize international radiation the Effects of Atomic Radiation (UNSCEAR). harmonization in safety standards which draw upon information In developing the BSS, UNSCEAR provided radiation safety derived from extensive research and develop- the scientific information on which the stand- ment by scientific and engineering organiza- ards are based. The Committee — which was tions at national and international levels. For established by the UN General Assembly in its part, the IAEA has the statutory authoriza- 1955 and today includes representatives from tion to establish or adopt, in consultation and, 21 countries — compiles, assesses, and dis- where appropriate, in collaboration with the seminates information on the health effects of competent organs of the United Nations and radiation and on the levels of radiation ex- with the specialized agencies concerned, posure from different sources. standards of safety for protection of health...". International Commission on Radiologi- In discharging this function, the IAEA Board of cal Protection (ICRP). Radiation safety stand- Governors first approved Agency health and ards are based on the recommendations of the safety measures in March 1960. The Board ICRP, a non-governmental scientific organiza- approved the first version of the IAEA's Basic tion founded in 1928. Its most recent recommen- Safety Standards for in dations were issued in 1990 (Publication 60, June 1962 and a revised version in September Annals of the ICRP, Vol. 21, No.1-3)) and form 1965. A third revision was published by the IAEA the basis of the BSS. as the 1982 Edition of Safely Series No. 9; this International Commission on Radiation edition was jointly sponsored by the IAEA, fie Units and Measurements (ICRU). The quan- ILO, the OECD/NEA, and the WHO.* tities and units used in the BSS are primarily The Inter-Agency Committee on Radia- those recommended by the ICRU, a sister or- tion Safety (IACRS). A number of years ago, ganization of the ICRP. (See box, next page.) the IAEA promoted the formation of IACRS as The International Nuclear Safety Ad- a mechanism for consultation and collabora- visory Group (INSAG). This advisory body of tion in radiation safety matters with competent nuclear safety experts serves as a forum for organs of the United Nations and with the the exchange of information and for the specialized agencies. The Committee aims provision of advice to the IAEA on safety is- inter alia to encourage the co-ordination of sues of international significance. In 1988, it policies and consistency in radiation safety issued through the IAEA the Basic Safety Prin- principles and standards. Members are the ciples for Plants (Safety Series FAO, ILO, NEA/OECD, PAHO, UNSCEAR, No. 75-INSAG-3). Many of these principles are WHO, Commission of the European Com- relevant to the safety of other radiation sour- munities (CEC) and the IAEA. A number of ces and installations and have been used in organizations — the ICRP, the International the BSS. Commission on Radiation Units and Measure- ments (ICRU), the International Electrotechni- cal Commission (IEC), the International Radiation Protection Association (IRPA) and * For a description of these previous international the International Standards Organization standards see the author's article in the IAEA Bul- (ISO) — have observer status. letin; Vol. 25, No. 3; (September 1983).

posed to radiation, especially of the survivors of the advance, may be expected to increase the back- atomic bombing of Hiroshima and Nagasaki, have ground exposure that people already receive: demonstrated that exposure to radiation also has a they are termed practices. potential for the delayed induction of malignancies On the other hand, there are radiation ex- and possibly of hereditary effects. These radiation posures incurred de facto by people. The ac- effects cannot be related to any particular in- tivities which are intended to reduce these ex- dividual exposed but can be inferred from posures are termed interventions. epidemiological studies of large populations; Because of the radiation effects on health, they are called effects because of their practices and interventions need to be subject to aleatory statistical nature. (See box, next page.) certain standards of radiation safety to protect Human activities and radiation exposure: those persons adventitiously exposed.The BSS practices and interventions. Many beneficial are intended to harmonize internationally the human activities involve the exposure of people basic requirements for protecting people against to radiation from both natural and man-made undue radiation exposure in practices and inter- sources. These activities, which are planned in ventions. (See box, page 5.)

IAEA BULLETIN, 2/1994 FEATURES

Radiation health effects

Exposure to radiation can cause detrimental health ef- impair the function of the exposed tissue. The severity of a fects. At large acute doses, radiation effects — such as particular deterministic effect is higher as doses increase nausea, reddening of the skin and, in severe cases, acute above the threshold which varies depending on the type of syndromes — are clinically expressed in exposed in- effects. The lower thresholds are a few for acute dividuals within a short period of time after exposure. Large exposures and a few hundred millisieverts per year for chronic dose rates also cause clinically detectable chronic exposures. The likelihood of incurring the deter- deleterious effects. These effects are called deterministic ministic effect, therefore, is nil at lower doses and ap- because they are certain to occur if the dose exceeds a proaches certainty at threshold doses. certain threshold level. Stochastic effects may develop if an irradiated cell is At low doses as well, radiation exposure can plausibly modified rather than killed. Modified cells may, after a prolonged induce severe health effects, such as malignancies, which delay, develop into a . The body's repair and defense are statistically detectable in a population, but cannot be mechanisms make this a very improbable outcome as closes unequivocally associated with an exposed individual. become small; nevertheless, there is no evidence of a threshold Hereditary effects due to radiation exposure have been dose below which cancer cannot result. The probability of statistically detected in mammals and are presumed to occur occurrence of cancer is higher for higher doses, but the severity in humans as well. All these statistically detectable effects of any cancer that may result from is independent of are called stochastic effects because of their aleatory the dose. If a stem cell whose function is to transmit genetic nature.These effects are expressed after a latency period, information is damaged owing to radiation exposure, it is con- presumably over the entire range of doses without a ceivable that hereditary effects of various types may develop in threshold level. In addition, there is a possibility of health the descendants of the exposed person.The likelihood of effects in children exposed to radiation in utero during stochastic effects is presumed to be proportional to the dose certain periods of pregnancy, including a greater likelihood received without dose threshold. The likelihood of severe radia- of leukaemia and severe mental retardation. tion-induced stochastic effects during a lifetime is currently Deterministic effects are the result of a process of cell killing estimated to be around 5% per of radiation dose for the due to radiation exposure, which, if extensive enough, can general population.

Quantities and units in radiation safety

Although most of the requirements of the BSS are qualita- The effective dose is the quantity resulting from the sum tive by nature, they also establish quantitative limitations and total of the equivalent doses weighted by the radiosensitivity guidance levels. The quantities and units used in the BSS are of organs and tissues for all exposed organs and tissues in based on the ICRP and ICRU recommendations. an individual.The unit of and effective The main physical quantities on which the BSS are dose is the same as the unit of , namely based are: the activity or rate of emission of radiation from per , but the name used for the unit is sievert (Sv). a and; the absorbed dose or energy absorbed When are taken into the body, the resulting by a unit of a substance from the radiation to which it dose is received throughout the period of time such is exposed. radionuclides remain in the body. The unit of activity is the reciprocal (number of The is the total dose delivered during the emissions per second) which is named (Bq). The period of time the radionuclides remain in the body, and is unit of absorbed dose is the joule per kilogram, called the calculated as the time integral of the rate of receipt of the dose. (Gy). Any relevant dose restriction is applied to the committed dose The absorbed dose is the basic physical dosimetric from the intake. The unit of committed dose is the sievert. quantity of the BSS but it is not entirely satisfactory for The total impact of the radiation exposure delivered by a radiation protection purposes because effectiveness in given practice or source depends on the number of in- damaging human tissue differs for different types of ionizing dividuals exposed and on the dose they receive. radiation. Consequently, the absorbed dose in tissues is The , defined as the summation of the multiplied by a weighting factor to take account of the effec- products of the mean dose in the various groups of ex- tiveness of the given type of radiation in inducing health posed people and the number of individuals in the group, effects. is therefore used to characterize the radiation impact of a The equivalent dose is the quantity resulting from practice or source.The unit of collective dose is the weighting the absorbed dose with the effectiveness of the man-sievert. radiation type. But the likelihood of injurious effects due to a For operational purposes, the BSS use the ambient given equivalent dose differs for different organs and tissues. dose equivalent and the personal dose equivalent.These Consequently, the equivalent dose to each organ and tissue are quantities defined by the ICRU to facilitate measure- is multiplied by a tissue weighting factor to take account of ment and monitoring while conforming with the radiation the organ radiosensitivity. protection basic quantities.

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Objective of the BSS Practices and interventions The declared aim of the BSS is to prevent the occurrence of deterministic effects of radiation Planned human activities that add radiation exposure to that which and to restrict the likelihood of occurrence of people normally receive due to , or that increase stochastic effects. the likelihood of incurring exposure, are termed practices. The human For any justified practice, the objective is activities that seek to reduce the existing radiation exposure, or the achieved by requirements for protecting the ex- existing likelihood of incurring exposure, are termed interventions. posed individuals and for ensuring the safety of The BSS apply to both the commencement and the continuation of practices that involve or could involve radiation exposure, and also the source of exposure. Thus, to existing, de facto situations in which exposure or its likelihood can • the risk to any exposed individual is res- be reduced or ruled out by means of some intervention. For a practice, tricted, regardless of where or when the in- provisions for radiation protection and safety can be made before its dividual would commit the exposure, by keeping commencement, and the associated radiation exposures and their individual doses below specific dose limits; and likelihood can be constrained from the outset. In the case of interven- • any source of exposure is kept safe by, inter tion, the circumstances giving rise to exposure or the likelihood of alia, a) constraining both the doses expected to exposure already exist, and their reduction can only be achieved by be delivered by it with certainty and also the means of remedial or protective actions. probability of delivering radiation doses due to The table presents the UNSCEAR summary of the relative (potential) exposures that may but are not certain radiological impact from some practices as well as from severe to occur; b) keeping the delivered doses, the accidents that required intervention. The levels of radiation exposure probabilities of incurring doses, and the number are expressed as equivalent periods of exposures to natural sources. of exposed individuals as low as reasonably achievable under the prevailing circumstances; and c) applying to the source a number of ad- Levels of radiation exposure ministrative, technical, and managerial require- Exposure resulting Basis Equivalent period of ments intended to ensure its safety. from global exposure to For any justified interventions, the objective average natural is achieved by: background • keeping, under any foreseeable circumstance, the individual doses lower than the threshold Nuclear weapons All past tests 2.3 years testing levels for deterministic effects; and Apparatus and One year of practice at • keeping all doses expected to be averted by substances used in the current rate 90 days the intervention as low as reasonably achievable medicine under the prevailing circumstances. Severe accidents Accidents to date 20 days Nuclear power Total nuclear generation (under generation to date 10 days Scope of the BSS normal operating One year of practice at conditions) the current rate 1 Exclusions. Any radiation exposure essential- Occupational One year of ly unamenable to control through the BSS require- activities occupational activities at the current rate 8 ments is excluded from the BSS scope. Examples are the exposure caused by the naturally radioactive , which is a normal constituent of the body, exposure to cosmic rays at ground level, and sources within those practices, provided they are generally other naturally occurring exposures. not exempted from the BSS requirements, and to The BSS, moreover, only apply to: any interventions, including any related exposures. • human beings (it is considered that standards Practices. The practices to which the BSS of protection that are adequate for this purpose apply include: will also ensure that no other species is • the use of radiation or radioactive substances threatened as a population, even if individuals of for medical, industrial, agricultural, educational, the species might potentially be harmed); and training, and research purposes; and • ionizing radiation, namely gamma and X- • the generation of energy by nuclear power, rays and alpha, beta and other particles that can comprising any activity in the induce ionization; (the BSS do not apply to non- which involves or could involve exposure to ionizing radiation, neither do they apply to the radiation or radioactive substances. control of other non-radiological aspects of Sources. Within a practice, the BSS apply to health and safety). any source of radiation being used in the prac- Apart from these exclusions, the BSS scope tice, both natural sources and artificial sources, extends to any practices, including any radiation including:

IAEA BULLETIN, 2/1994 FEATURES

The justification of practices and interventions

The justification of practices and interventions having regard to health, social and economic involves many factors, including social and politi- factors. The BSS establish that protective ac- cal aspects, with radiological considerations usual- tions shall be nearly always justified if the ly playing a minor role. Some practical guidance doses in an intervention situation are expected on justification for practices and interventions to approach the values in the table below. provided by the BSS is summarized here. However, actual intervention levels should be Unjustified practices. The BSS provide optimized and usually to much lower guidance on unjustified practices. These prac- doses (see table, page 10). tices include those that would result in an increase of the amount of radioactive substan- Individual dose levels at which Intervention ces in food, beverages, cosmetics, or other shall be expected under any circumstances commodity or product intended for ingestion, inhalation or percutaneous intake by, or ap- Acute exposures plication to, a human being (except for medical purposes); and practices involving the Organ or Tissue Projected absorbed frivolous use of radiation in commodities or dose to the organ or products such as toys, personal jewelry, or tissue in less than 2 adornments. Additionally, certain medical ex- days(Gy) posures are also deemed to be not justified: Whole body radiological examination for occupational, legal, or health insurance purposes; radiologi- Skin cal examinations for theft detection purposes; exposure of population groups for purposes Lens of the eye of mass screening; and the exposure of humans for medical research (unless it is in Gonads accordance with the provisions of the Helsinki Declaration, follows the guidelines for its ap- Chronic exposures plication prepared by the Council for Interna- tional Organizations of Medical Sciences Organ or Tissue Annual equivalent (CIOMS) and WHO, and is subject to the dose rate (Sv/year) advice of an Ethical Review Committee and Gonads 0.2 to applicable national and local regulations). Lens of the eye 0.1 Interventions. Intervention shall be justified marrow 0.4 if it is expected to achieve more good than harm,

• radioactive substances and devices that con- empted source are negligible and that the collec- tain radioactive substances or produce radiation, tive radiological impact does not warrant such as consumer products, sealed sources, un- regulatory concern. Moreover, an exempted sealed sources, and radiation generators; and source must be inherently safe. • installations and facilities which contain The exemption criteria are also expressed in radioactive substances or devices which produce exemption levels, i.e. levels of [radioactivity or radiation, such as irradiation installations, mines activity concentration in materials below which and mills processing radioactive ores, installa- exemption is almost automatic. tions processing radioactive substances, nuclear Materials and objects from practices and installations, and management sources already subject to BSS requirements facilities. (When an installation could release may be released from these requirements subject radioactive substances or emit radiation into the to satisfying clearance levels which shall not environment, it is as a whole considered as a exceed the specified exemption levels. source and the BSS apply to each individual Interventions. The intervention situations to source of radiation within the installation and to which the BSS apply include any de facto situa- the installation as a whole.) tion causing people's exposure which can jus- Exemption and clearance. Practices, and tifiably be reduced by intervention measures. sources within a practice, may be exempted from These include: BSS requirements if they meet established ex- • emergency situations such as those created emption criteria. The exemption criteria ensure by environmental contamination in the aftermath that the individual risks arising from an ex- of an accident; and

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• chronic situations such as exposure to natural sources of radiation (e.g. radon in dwellings) and individual dose limitation to radioactive residues from previous events and activities (e.g. chronic environmental con- The dose limits established by the BSS are intended to ensure tamination from past activities). that no individual is committed to unacceptable risk due to radiation Exposures. The BSS apply to any exposure exposure. due to: • any relevant practice or source, including: Dose Limits for Occupational Exposure normal exposures (i.e. exposures that are certain • an effective dose of 20 mSv per year averaged over 5 consecutive to occur); potential exposures (i.e. exposures that years; may or may not occur); occupational exposures • an effective dose of 50 mSv in any single year; (i.e. exposures of workers); medical exposures • an equivalent dose for the lens of the eye of 150 mSv in a year; (i.e. mainly exposures of patients); or public ex- and posures (i.e. the remaining type of exposures). • an equivalent dose for the extremities (hands and feet) and for the • any relevant intervention situation involving: skin of 500 mSv in a year. emergency exposure, including exposures re- (In special circumstances, workers undertaking intervention may quiring prompt intervention and other temporary be exposed to up to 100 mSv in a single year.) exposure due to situations in which an emergen- cy plan or emergency procedures have been ac- Dose Limits tor Members of the Public tivated; and chronic exposure, including ex- posure to natural radiation sources, exposure due • an effective dose of 1 mSv in a year; to radioactive residues from previous events, and • in special circumstances, an effective dose up to 5 mSv in a single exposure due to radioactive contamination from year provided that: the average dose over 5 consecutive years does practices and sources which, for whatever not exceed 1 mSv per year; and the dose for special circumstances reason, have not been under regulatory control. is specifically authorized by the regulatory authority; Natural sources. According to the BSS, ex- • an equivalent dose for the lens of the eye of 15 mSv in a year; and • an equivalent dose for the skin of 50 mSv in a year. posure to natural sources shall normally be con- sidered as a chronic exposure situation and be Application of the Dose Limits subject to requirements for intervention. Excep- tions to this are: activities involving natural sour- The dose limits apply to the sum of the relevant doses from ces that cause increased public exposure due to, external exposure in the specified period and the relevant committed for example, discharges of radioactive substan- doses from intakes in the same period (the period for calculating the ces into the environment and certain occupation- committed dose shall normally be 50 years for adults and 70 years for al exposures to radon which shall be subject to intakes by children). Compliance with this requirement can be deter- the requirements for practices if the intervention mined through compliance with the condition that the personal dose cannot reduce such exposure below action levels equivalent from penetrating radiation during the year plus the sum of given by the BSS. committed doses due to the intake of radionuclides during the year are lower than the relevant limit.

Obligations

The BSS establish general obligations in by undertaking remedial or protective actions in relation to both practices and interventions. The accordance with the requirements of the BSS. obligations are that, unless the exposure is ex- Additionally, the BSS establish that any cluded from the BSS: source containing radioactive substances shall be • no practice shall be adopted, introduced, con- transported in accordance with the provisions of ducted, discontinued, or ceased and no source the IAEA Regulations for the Safe Transport of within the practice shall, as applicable, be mined, Radioactive Material (Safety Series No. 6, IAEA, milled, processed, designed, manufactured, con- Vienna (1990)) and with any applicable interna- structed, assembled, acquired, imported, ex- tional convention. ported, sold, loaned, hired, received, sited, lo- cated, commissioned, possessed, used, operated, maintained, repaired, transferred, decommis- Requirements sioned, transported, stored or disposed of, except in accordance with the requirements of the BSS, To enable fulfillment of the above obliga- unless the practice or source is exempted from tions, the BSS establish the basic requirements the requirements of the BSS; and for protection and safety. • whenever justified, existing de facto ex- The requirements have to be fulfilled in all posures shall be reduced through intervention, activities involving radiation exposure with the

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public authorities and services, employers and Guidance levels for diagnostic radiological procedures workers, specialized radiation protection bodies, for a typical adult patient and safety and health committees, laying down basic principles and indicating the different aspects that should be covered by an effective Examination Entrance surface absorbed dose radiation protection programme. per radiograph (mGy) Moreover, they are not intended to be applied AP 10 as they stand in all countries and regions. Rather, Lumbar spine LAT 30 they should be interpreted to take account of local LSJ 40 situations, technical resources, and the scale of installations — factors which will determine the Abdomen, intravenous urography & AP 10 cholecystography potential for application. As the BSS cover a broad range of practices and sources, many of the require- Pelvis AP 10 ments have been drafted in general terms so that Hip joint AP 10 any given requirement may have to be fulfilled Chest PA 0.4 differently according to the type of practice, and LAT 1.5 source, or intervention, the nature of the operations, Thoracic spine AP 7 and the potential for exposures. LAT 20 Requirements for practices. The BSS in- Dental Periapical 7 clude requirements for administration, radiation AP 5 protection, management, technological aspects Skull PA 5 and verification: LAT 3 Administrative requirements. These include notification of intentions to carry out practices; PA= Posterior - anterior projection, LAT= Lateral protection, LSJ= Lumbo- sacral-pm projection; AP= registration or licensing of sources; respon- Anterior • posterior protection sibility of registrants and licensees; and exemp- tion and decontrol (clearance) of sources. Radiation protection requirements.The.se include justification of practices; dose limits for Examination Multiple scan average absorbed individuals; optimization for protection and dose (mGy) safety; dose constraints for sources; and Head 50 guidance levels for medical exposure. (See boxes and tables, pages 5. 6, 7, and 8.) Lumbar spine 35 Management requirements. These include Abdomen 25 safety culture; quality assurance; human factors; and qualified experts. (See box, page 9.) Technical requirements. These include security; defense in depth; and good engineering Average glandular dose per cranlo-caudal projection practice. (See box, page 9.) 1 mGy (without grid) Verification. This includes safety assess- 3 mGy (with grid) ments; compliance; and records. Requirements for intervention. The BSS es- tablish administrative and radiation protection re- quirements for intervention as follows: Mode of operation Entrance surface absorbed dose Administrative requirements. These include rate (mGy/min) responsibilities of intervening organizations, Normal 25 registrants and licensees; and notification of situations requiring protective actions. High level 100 Radiation protection requirements. These include justification of intervention; and optimiza- tion of intervention and action levels. I See box and tables, page 6 and 10.) force that is derived from the statutory provisions The BSS are appended with detailed require- of the sponsoring organizations. They do not ments for all types of exposure as follows: entail any obligation for States to bring their For occupational exposures: Responsibi- legislation into conformity with them, nor are lities of employers, registrants, licensees, they intended to replace the provisions of nation- workers; conditions of service (special compen- al laws or regulations, or the standards in force. satory arrangements, pregnant workers, alterna- Rather, they aim to serve as a practical guide for tive employment, conditions for young persons):

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BSS technical requirements

The BSS establish technical requirements consequences of any such accident, if it does that address: occur; and e restoring sources to safe condi- tions after any such accident. Security of sources. Sources are to be kept Good engineering practice. As ap- secure so as to prevent theft or damage and to plicable, the siting or location, design, con- prevent any unauthorized person from carrying struction, assembly, commissioning, opera- out any of the actions specified in the obligations tion, maintenance, and decommissioning of of the BSS, by ensuring that: • control of a sources within practices is to be based on source not be relinquished without complying sound engineering which shall, as ap- with all relevant requirements specified in the propriate: • reflect approved codes and relevant registration or licence and without im- standards and other appropriately docu- mediately communicating to the Regulatory mented instruments; • be supported by reli- Authority, and when applicable to the relevant able managerial and organizational features, sponsoring organization, information regarding with the aim of ensuring protection and safety any lost, stolen, or missing source; • a source throughout the life of the sources; • include not be transferred unless the receiver posses- sufficient safety margins for the design and ses a valid authorization; and • a periodic construction of the sources and for operations inventory of sources be conducted at a fre- involving the sources, such as to assure reli- quency appropriate to confirm that they are in able performance during normal operation, their assigned locations and are secure. taking into account quality, redundancy, and Defense In depth. A multilayer system of inspectability, with emphasis on preventing protection and safety provisions commensurate accidents, mitigating their consequences, with the radiation hazards involved is to be ap- and restricting any future exposures; and • plied to sources, such that a failure at one layer take account of relevant developments in is compensated for or corrected by subsequent technical criteria, as well as the results of any layers, for the purposes of: • preventing acci- relevant research on protection or safety and dents that may cause exposure; • mitigating the lessons from experience.

BSS management requirements

The BSS has established a number of management to accidents and other events that could give rise to ex- requirements to ensure radiation safety. They address: posures, by ensuring that: • all personnel on whom protec- tion and safety depend be appropriately trained and Safety culture. A safety culture is to be established and qualified such that they understand their responsibilities maintained which encourages a questioning and learning at- and perform their duties with appropriate judgement ac- titude to protection and safety and to discourage complacency, cording to defined procedures; • sound ergonomic prin- by ensuring that: • policies and procedures be established that ciples be followed as appropriate in designing equipment identify the protection and safety of the public and workers as and operating procedures, so as to facilitate the safe opera- being of the highest priority; • problems affecting protection and tion or use of equipment, to minimize the possibility that safety be promptly identified and corrected, commensurate with operating errors will lead to accidents, and to reduce the their importance; • each individual's responsibilities including possibility of misinterpreting indications of normal and ab- those at senior management levels for protection and safety be normal conditions; • appropriate equipment, safety sys- clearly identified and that each individual be suitably trained and tems, procedural requirements, and other necessary qualified; • dear lines of authority for protection and safety provisions be provided to reduce, as far as practicable, the decisions be established; and • organizational arrangements possibility that human error will lead to inadvertent or unin- and lines of communications be established that result in an tentional exposure of any person; • means be provided for appropriate flow of protection and safety information at and detecting human errors and for correcting or compensating between the various levels of the organization. for them; and • intervention in the event of failure of safety Quality assurance (QA). QA programmes are to be es- systems or of other protective measures be facilitated. tablished that provide, as appropriate: • adequate assurance Qualified experts. Qualified experts are to be identified that the specified requirements related to protection and safety and made available for providing advice regarding the ob- are satisfied; and • quality control mechanisms and proce- servance of the BSS. Registrants and licensees have to dures to review and assess the overall effectiveness of inform the Regulatory Authority of the arrangements made protection and safety measures. to provide the expertise necessary for observance of the Human factors. Provisions are to be made for reduc- BSS. This information shall include the scope of the func- ing as far as practicable the contribution of human error tions of any qualified experts identified.

IAEA BULLETIN, 2/1994 FEATURES

Guidelines for intervention levels Urgent protective actions in emergency exposure Action Avertable dose situations Sheltering 1 0 mSv for a period of no more than 2 days Iodine prophylaxis 1 00 mGy (committed absorbed dose to the thyroid) Evacuation 50 mSv for a period of no more than 1 week

Withdrawal and substitution of foodstuffs (From the CODEX Alimentarius Commission guideline levels for radionuclides in food moving in international trade following accidental contamination)

Radionuclides Foods destined for general Milk, infant foods, and drinking consumption (kBq/kg) (kBq/kg) Caesium-134, Caesium-137, 1 1 Ruthenium-103, Ruthenium-106, Strontium-89 lodine-131 0.1 Strontium-90 0.1 Americium-241, -238, 0.01 0.001 Plutonium-239

Long-term actions

Action Avertable dose Initiating temporary relocation 30 mSv in a month Terminating temporary relocation 1 0 mSv in a month Considering permanent resettlement 1 Sv in a lifetime

and requirements for classification of areas; local For emergency exposure situations: Respon- rules and supervision; personal protective equip- sibilities; emergency plans; intervention for ment; co-operation between employers, emergency exposure situations; assessment and registrants and licensees; individual monitoring monitoring after accidents; cessation of interven- and exposure assessment; monitoring of the tion after an accident; protection of workers un- workplace; health surveillance; records; and dertaking an intervention. dose limitation in special circumstances. For chronic exposure situations: Respon- For medical exposure: Responsibilities; jus- sibilities; remedial action plans; action levels for tification of medical exposures; optimization of chronic exposure situations. protection for medical exposures; guidance levels; dose constraints; maximum activity in therapy patients discharged from hospitals; investigation An international effort of accidental medical exposures; records. For public exposure: Responsibilities; con- The BSS establish a large number of interre- trol of visitors; sources of external irradiation; lated requirements aimed at ensuring radiation radioactive contamination in enclosed spaces; protection and safety. (See figure, next page.) radioactive waste; discharge of radioactive sub- Although the majority of requirements are of a stances into the environment; radiation and en- qualitative nature, the BSS also establish many vironmental monitoring; consumer products. quantitative requirements in terms of restrictions For potential exposure — safety of sources: or guidance on the dose that may be incurred by Responsibilities; safety assessment; require- people. The range of these doses is large, spread- ments for design; requirements for operations; ing over four orders of magnitude: from doses quality assurance. that are considered so as not to warrant

10 IAEA BULLETIN, 2/1994 FEATURES

1mplicit quantitative requirements How the BSS work for practices and guidance for practices Notification of a practice Annual dose 1000 : (mSv)

- -« j Intervention always justified j Yes, exposure is unamenable to control Outside _ f i Limit for workers undertaking 100 : intervention the BSS scope ; t i Limit for workers I (normal practice, yearly)

- f Limit for workers (normal practice, average)

10 _, *r—j Range for optimized interventions | ; ]-•—i — i —(flang e for optimized remedial action (radon)| - > ^_ Range for optimized protection ~ and constraints (occupational) Yes, doses are trivial and the BSS - " '•— Wor/d average background exposure source is inherently safe requirements 1 „ Public dose limit do not apply : (individual members of the public)

^ Range of constraints No (public, individual sources)

0.1 zr

- •"— Range of optimized protection (public) No, e.g. it involves frivolous use of radiation

0.01 — • Exemption level

Yes

The BSS encompass a large number of interrelated No, the public or occupational requirements which, in their entirety, provide adequate Is exposure of an individual protection and safety. It is therefore impossible to individual will exceed dose limits Practice paraphrase these requirements without losing their dose limitation rejected essence. The figure at right, however, attempts to provide respected? a simplified visual description on how the BSS work for practices. The chart presumes compliance with the administrative requirements for registration or licensing.

regulatory concern, but rather exemption from No, doses are not ALARA the requirements, to doses that are so large as to Is the or exceed constraints protection make intervention almost mandatory. (See figure.) optimized? The BSS mark the culmination of attempts that have continued over the past several decades towards the harmonization of radiation protec- No, the source does not comply with managerial or tion and safety standards internationally. Follow- technical requirements ing this unprecedented international effort to draft and review the Standards, the BSS were endorsed at a meeting of a Technical Committee held at IAEA headquarters in Vienna in Decem- Are protection ber 1993. It was attended by 127 experts from 52 and safety countries and 11 organizations. verified? Yes, it is below The IAEA's Board of Governors is expected to Yes clearance approve the BSS soon. Thereafter, the IAEA will / oan levels Registration No ' issue the BSS in an interim publication (in English / sourc or ^^ decent only). Once the Standards have been formally Licensing endorsed by the other sponsoring organizations, they will be issued in the IAEA Safety Series as a final publication in Arabic, Chinese, English, French, Russian and Spanish. G

IAEA BULLETIN, 2/1994 11