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Hanford External Dosimetry Technical Basis Manual PNL-MA-842

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Hanford External Dosimetry Technical Basis Manual PNL-MA-842 PNNL-15750 Rev. 1 PNL-MA-842 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Hanford External Dosimetry Technical Basis Manual PNL-MA-842 B. A. Rathbone January 1, 2010 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. PACIFIC NORTHWEST NATIONAL LABORATORY operated by BATTELLE for the UNITED STATES DEPARTMENT OF ENERGY under Contract DE-AC05-76RL01830 Printed in the United States of America Available to DOE and DOE contractors from the Office of Scientific and Technical Information, P.O. Box 62, Oak Ridge, TN 37831-0062; ph: (865) 576-8401 fax: (865) 576-5728 email: [email protected] Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm Preface The Hanford External Dosimetry Program (HEDP) provides support to the U.S. Department of Energy’s Richland Operations Office (RL), Office of River Protection (ORP), Pacific Northwest Site Office (PNSO), and DOE contractor radiation protection organizations in determining doses-of-record from external sources of radiation. The Pacific Northwest National Laboratory (PNNL) (a) administers the HEDP in coordination with Hanford contractor radiation protection organizations to ensure consistent site-wide implementation of external dosimetry practices for Hanford workers and visitors. Coordination of dosimetry practices at Hanford is accomplished through the Hanford Personnel Dosimetry Advisory Committee (HPDAC). Technical services provided by the HEDP include personnel, area, nuclear accident, and environmental dosimetry capabilities that comply with DOE requirements in 10 CFR 835 Occupational Radiation Protection (DOE 2007a), DOE/EH-0027 Department of Energy Standard for the Performance Testing of Personnel Dosimetry Systems (DOE 1986a) and DOE/EH-0026 Handbook for the Department of Energy Accreditation Program for Personnel Dosimetry Systems (DOE 1986b) as well as DOE guidance in DOE G 441.1-1C Radiation Protection Programs Guide (DOE 2008a). The primary purposes of this Hanford External Dosimetry Technical Basis Manual are to document the design and implementation of the external dosimetry system used at Hanford, and to document the rationale for the measurement methods used. This manual includes documentation of the technical basis for the dosimeter design, processing protocols, dose calculation methodology, and recommended dosimeter use in the field, in a manner intended to demonstrate compliance with 10 CFR 835 and to ensure the defensibility of the doses of record. Secondary purposes of this manual are to provide general information on dosimeter response characteristics and guidance on the proper use and limitations of Hanford dosimeters that will be of use to Hanford radiation protection organizations. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of HEDP. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the HPDAC which is chartered and chaired by DOE. This manual supports the Radiation Protection Programs of Hanford contractors. RL, ORP, PNSO and DOE contractors overseen by these DOE offices will be implementing new requirements in the June 8, 2007 Amendment to 10 CFR 835 Occupational Radiation Protection (DOE 2007a) beginning January 1, 2010. This revision of PNL-MA-842 is consistent with the new requirements and intended for use by these entities on or after January 1, 2010. (a) Pacific Northwest National Laboratory is operated by Battelle Memorial Institute for the U.S. Department of Energy under Contract DE-AC05-76RLO 1830. Issued: January 2010 PNL-MA-842: Preface Supersedes: August 2009 Page iii THIS PAGE INTENTIONALLY LEFT BLANK Issued: January 2010 PNL-MA-842: Preface Supersedes: August 2009 Page iv Glossary absorbed dose, D (1) The absorbed dose, D, is the quotient of d by dm , where d is the mean energy imparted by ionizing radiation to matter of mass dm , thus d D dm Unit: J kg-1 The special name for the unit of absorbed dose is gray (Gy). This ICRU definition of the absorbed dose, D, as a point function, allows the specification of the spatial variations of D as well as the distribution of the absorbed dose in linear energy transfer at the point of interest. (a) (2) Absorbed dose (D) means the average energy imparted by ionizing radiation to the matter in a volume element per unit mass of irradiated material. The absorbed dose is expressed in units of rad (or gray) (1 rad = 0.01 gray). (b) The special unit of absorbed dose is the rad, where 1 rad = 1 erg per gram. One Gy = 100 rad. The material of interest for absorbed dose (as used in this manual) is typically soft tissue or a phantom approximating soft tissue in composition, but may also include detector materials such as air, methane, silicon, or TLD chip. accident dosimetry Determination of high levels of deep absorbed dose resulting from uncontrolled conditions. accreditation The DOE process of granting accreditation based on onsite assessment against the DOELAP handbook (DOE 1986a) and dosimeter performance testing against the DOELAP standard (DOE 1986b). Accreditation must be updated every two years. air kerma-to-dose-equivalent The numerical quantity that relates the air kerma to the dose conversion factors equivalent at a specified depth in a phantom of specified geometry (Ck factors) and composition. Factors are a function of the photon energy and angular distribution. (a) This is the definition given by the International Commission on Radiation Units and Measurements in ICRU Report 51 Quantities and Units in Radiation Protection Dosimetry (ICRU 1993). It is also the definition used in ANSI/HPS N13.11-2009 American National Standard for Dosimetry - Personnel Dosimetry Performance - Criteria for Testing (HPS 2009). (b) This is the definition given by DOE in 10 CFR 835 (DOE 2007a). The DOE definition might better be characterized as “average absorbed dose” in the volume element or tissue of interest. In this manual, the term “absorbed dose” may used in a manner consistent with either the DOE or the ICRU definition. Issued: January 2010 PNL-MA-842: Glossary Supersedes: August 2009 Page v ALARA ALARA is an acronym for "As Low As is Reasonably Achievable," which is the approach to radiation protection to manage and control exposures (both individual and collective) to the work force and to the general public to as low as is reasonable, taking into account social, technical, economic, practical, and public policy considerations. ALARA is not a dose limit but a process which has the objective of attaining doses as far below the applicable limits of this part as is reasonably achievable. albedo effect As used in this document, the neutron dosimeter response caused by the moderating and backscattering properties of a phantom or the human thorax for neutron radiation. alpha radiation Alpha particles are defined as a helium nucleus with a plus-2 positive charge. ambient dose equivalent, H*(d) Denoted as H*(d) at a point in a radiation field is the dose equivalent that would be produced by the corresponding expanded and aligned field in the ICRU sphere at a depth, d, on the radius opposing the direction of the aligned field. The SI unit of ambient dose equivalent is joule per kilogram (J kg-1) and its special name is sievert (Sv). The special unit of ambient dose equivalent is rem. One sievert = 100 rem. Ambient dose equivalent is an operational quantity. angular response The response of a dosimeter or instrument as a function of the angle of incidence of radiation (where normal incidence is designated as zero degrees). The data may be normalized to the response at zero degrees. angular dependence Angular dependence of response (same meaning as angular response). background In the 10 CFR 835 definition, background means radiation from (i) naturally occurring radioactive materials which have not been technologically enhanced; (ii) cosmic sources; (iii) global fallout as it exists in the environment (such as from the testing of nuclear explosive devices); (iv) radon and its progeny in concentrations or levels existing in buildings or the environment which have not been elevated as a result of current or prior activities; and (v) consumer products containing nominal amounts of radioactive material, or producing nominal amounts of radiation. beta particle An electron or positron emitted from a nucleus during beta decay. beta radiation Radiation consisting of beta particles. bias, B The average of the performance quotients, Pi for n dosimeters, for a specified radiation category and test quantity n 1=i Pi = P B P = n Issued: January 2010 PNL-MA-842: Glossary Supersedes: August 2009 Page vi calibration Calibration means to adjust and/or determine either: (1) The response or reading of an instrument relative to a standard (e.g., primary, secondary, or tertiary) or to a series of conventionally true values; or (2) The strength of a radiation source relative to a standard (e.g., primary, secondary, or tertiary) or conventionally true value.
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