RIS 2009-09, Withdrawn NRC Regulatory Issue Summary 2009-09: Use of Multiple Dosimetry and Compartment Factors in Determining Effective Dose Equivalent from External Radiation Exposures
| ML082320040 | |
| Person / Time | |
|---|---|
| Issue date: | 07/13/2009 |
| From: | Dan Dorman, Robert Lewis, Mcginty T NRC/FSME/DMSSA, NRC/NMSS/FCSS, Division of Policy and Rulemaking |
| To: | |
| lgs1 | |
| References | |
| RIS-09-009 | |
| Download: ML082320040 (8) | |
Withdrawn NRC Regulatory Issue Summary 2009-09, Use of Multiple Dosimetry and Compartment Factors in Determining Effective Dose Equivalent from External Radiation Exposures, dated July 13, 2009, has been withdrawn.
ADAMS Accession Number: ML082320040
See Federal Register notice dated October 25, 2016
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
OFFICE OF FEDERAL AND STATE MATERIALS AND
ENVIRONMENTAL MANAGEMENT PROGRAMS
WASHINGTON, DC 20555-0001 July 13, 2009 NRC REGULATORY ISSUE SUMMARY 2009-09 USE OF MULTIPLE DOSIMETRY AND COMPARTMENT FACTORS IN
DETERMINING EFFECTIVE DOSE EQUIVALENT FROM EXTERNAL
RADIATION EXPOSURES
ADDRESSEES
All U.S. Nuclear Regulatory Commission (NRC) licensees, Agreement State Radiation Control Program Directors, and State Liaison Officers.
INTENT
The NRC is issuing this regulatory issue summary (RIS) to inform licensees of an acceptable method for determining effective dose equivalent (EDE) from external sources of radiation. This method is documented in a plant specific safety evaluation and has been determined to be generically applicable to licensees when employed consistent with the assumptions, limitations, and commitments identified in this safety evaluation. This RIS communicates the NRCs determination of generic applicability and provides a summary of the information contained in the safety evaluation. No specific action or written response is required. NRC is providing this RIS to the Agreement States for their information and for distribution to their licensees as appropriate.
The NRC staff will issue a Regulatory Guide that will combine and identify approved methods for determining EDE from external sources (EDEex), allowing the use of EDEex in place of deep dose equivalent (DDE) for demonstrating compliance with total effective dose equivalent (TEDE) requirements in Title 10 of the Code of Federal Regulations (10 CFR) Chapter 1.
BACKGROUND
Effective January 3, 2008, the definition of TEDE in 10 CFR Part 20, Standards for Protection against Radiation, was amended (see Volume 72, page 68043, of the Federal Register, dated December 4, 2007). The amendment redefined TEDE as the sum of the effective dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures). This change clarified that the EDEex could be used to demonstrate compliance with TEDE-based regulations.
In addition, the NRC revised 10 CFR 20.1201(c) to require that, when external exposure is determined by measurement with an external personal monitoring device, the DDE must be used in place of the EDEex, unless the licensee determines EDEex using a dosimetry method approved by the NRC. The NRC has approved several methods for determining EDEex, allowing the use of EDEex in place of DDE for demonstrating compliance with the TEDE
requirements in 10 CFR Part 20. These methods are discussed in RIS 2002-06, Evaluating Occupational Dose for Individuals Exposed to NRC-Licensed Material and Medical X-Rays, dated April 16, 2002; RIS 2003-04, Use of the Effective Dose Equivalent in Place of the Deep Dose Equivalent in Dose Assessments, dated February 13, 2003; and RIS 2004-01, Method for Estimating Effective Dose Equivalent from External Radiation Sources Using Two Dosimeters, dated February 17, 2004. The method described in this RIS is another approved method.
On December 20, 2004, Southern California Edison submitted a request to the NRC to use the compartment factors found in American National Standard Institute/Health Physics Society (ANSI/HPS) N13.41-1997 as part of a proposed method of multiple dosimetry (see Agencywide Documents Access and Management System (ADAMS) Accession No. ML043630036). The NRC staff found ANSI/HPS N13.41-1997 deficient in certain areas, thereby limiting its use for demonstrating compliance with TEDE-based regulations. For example, the ANSI/HPS standard lacks specificity for the placement of personal monitoring devices.
The NRC staff determined that the method proposed by Southern California Edison, to use the ANSI/HPS N13.41-1997 compartment factors for determining EDEex, including their commitment to monitor each compartment at the location of highest exposure, is acceptable. On May 10,
2005, the NRC approved the licensees request (see Safety Evaluation at ADAMS Accession No. ML051320194) concluding that the proposed method, as discussed further in this RIS, was technically sound and acceptable for the purposes of determining compliance with the TEDE-
based regulations in 10 CFR Chapter 1.
In developing this RIS, a stakeholder concern was raised by comment at a meeting, that some licensees using multiple dosimeters to monitor external radiation exposure (as with this EDE
method) may inappropriately reduce their work place radiation survey programs. Nothing in this RIS relieves the licensee of the survey requirements in 10 CFR 20 .1501(a), nor the requirements in 10 CFR 19.12 to inform the workers of workplace radiological hazards.
SUMMARY OF ISSUE
The method for determining EDEex described in this RIS, includes the use of the compartment factors provided in ANSI/HPS N13.41-1997, Criteria for Performing Multiple Dosimetry.
The multiple dosimetry method in ANSI/HPS N13.41-1997 divides the whole body into seven separate compartments. Each compartment, or composite compartment (since the ANSI/HPS
standard allows combining adjacent compartments), is monitored separately. The dose measurement for each compartment is the personal dose equivalent for penetrating radiation at a depth of 10 millimeters, or Hp(10). This Hp(10) is equivalent to the DDE as defined in 10 CFR Part 20. The Hp(10), or measured DDE, value is then weighted with the associated compartment factor (W c).
The factor for each compartment was developed by summing the stochastic weighting factors given in International Commission of Radiological Protection (ICRP) Publication 26 for all the organs located within that compartment. For each tissue that resides in more than one compartment (e.g., red bone marrow), the weighting factor is apportioned among the compartments based on the fraction of the total mass of the tissue residing in each using the information in ICRP Publication 23, Report of the Task Group on Reference Man.
Table 1 of ANSI/HPS N13.41-1997 lists the compartment factors as shown below:
Area of the Body/Compartment (c) Compartment Factor (W c)
Head and neck 0.10
Thorax, above the diaphragm 0.38 Abdomen, including the pelvis 0.50
Upper right arm 0.005 Upper left arm 0.005 Right thigh 0.005 Left thigh 0.005 EDEex is the sum of the products of the personal dose equivalent measured for each compartment and its associated compartment weighting factor, or:
HE = W C Hp,c(10)
Where HE = effective dose equivalent (or EDEex), W c = compartment factor for compartment c, and Hp,c(10) = personal dose equivalent (or DDE) for compartment c.
As noted above, ANSI/HPS N13.41-1997 allows two or more adjacent compartments to be combined into a single composite compartment. The compartment weighting factor for a composite compartment is the sum of the weighting factors of the individual compartments that make up the composite compartment. Although not a condition of the NRC approval, several of the licensees who have obtained a site-specific approval to use this method, monitor the thorax and abdomen compartments as a single composite compartment similar to the original proposal by Southern California Edison.
Fundamental to the compartment method of determining EDEex are the assumptions that (1) the average dose to the tissues in each compartment can be reasonably measured, and (2) the dose distribution across the compartment is sufficiently constant so that this average dose can be applied to each tissue in the compartment. The compartments defined in the standard are small enough so that under most normal exposure situations these assumptions are met and a single determination of DDE in each compartment is sufficient. However, this may not be the case in those unusual situations in which a significant dose gradient exists across one or more compartments (particularly the thorax and abdomen compartments). In these cases, the number and placement of dosimeters in each compartment becomes critical to ensuring that the EDEex is not underestimated.
To ensure that the estimates of EDEex are conservative, the licensee must measure the dose to each compartment (or composite compartment) by locating the dosimeter (calibrated to DDE) at the highest exposed portion of the respective compartment. The dosimeter location for each compartment is subject to the same criteria currently used to demonstrate compliance with
10 CFR 20.1201(c). [Note: monitoring each compartment, or composite compartment, at the location of highest exposure results in a conservative estimate of EDEex no matter what combination of compartments and composite compartments are used - even in the extreme case of combining all compartments into a single whole body composite compartment.] CONCLUSION
NRC licensees may use the compartment factors of ANSI/HPS N13.41-1997 and the methodology described in this RIS for implementing a multiple dosimetry program in compliance with TEDE-based regulations. This methodology is consistent with the NRC Safety Evaluation issued to Southern California Edison on May 10, 2005 (ADAMS Accession No. ML051320194).
It should be noted that the NRC has not directly approved ANSI/HPS N13.41-1997, in and of itself, for use by licensees in a personnel monitoring program. The NRC has only approved the use of the compartment factors and associated method for calculating EDEex, as described in this RIS, for use in a multiple dosimetry program when combined with the method presented herein.
This RIS communicates the generic applicability of this method to determine EDEex . Licensees may use this method for demonstrating compliance with TEDE-based regulations. Therefore, licensees are no longer required to apply for approval to use this method on a site-specific basis.
BACKFIT DISCUSSION
The purpose of this RIS is to inform licensees of a method for determining EDEex that has been approved by the NRC for use in determining TEDE in several site-specific licensee requests for approval (See additional safety evaluations at ADAMS Accession Nos. ML051320194, ML080570154, ML072220355, and ML061870512). The staff positions and guidance discussed in this RIS are the same as those that provide the technical basis for these site-specific approvals. This RIS requires no action or written response. 10 CFR Part 20 provides several options for demonstrating compliance with the TEDE dose limits. Any action on the part of addressees in accordance with the guidance contained in this RIS is voluntary. Consequently, the staff did not perform a backfit analysis.
FEDERAL REGISTER NOTIFICATION
The NRC did not publish a notice of opportunity for public comment on this RIS in the Federal Register because this RIS is informational and does not represent a departure from current regulatory requirements. Stakeholder comment was solicited in a September 10, 2008, public meeting. The draft RIS was attached to the meeting announcement (ADAMS ML082340248).
A summary of the comments received, and their resolutions, can be found at ADAMS Accession No. ML082540738.
CONGRESSIONAL REVIEW ACT
This RIS is not a rule as designated by the Congressional Review Act (5 U.S.C. § 801-886) and therefore is not subject to the Act.
PAPERWORK REDUCTION ACT STATEMENT
This RIS does not contain new or amended information collection requirements subject to the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et. seq.). Existing requirements were approved by the Office of Management and Budget (OMB), approval numbers 3150-0114,
3150-0005, and 3150-0006.
PUBLIC PROTECTION NOTIFICATION
The NRC may not conduct or sponsor, and a person is not required to respond to, a request for information or an information collection requirement unless the requesting document displays a current valid OMB control number.
CONTACT
Please direct any questions about this matter to the technical contact listed below.
/RA by MTschiltz for/ /RA/
Daniel Dorman, Director Robert J. Lewis, Director Division of Fuel Cycle Safety Division of Materials Safety and Safeguards and State Agreements Office of Nuclear Material Safety Office of Federal and State Materials and Safeguards and Environmental Management Programs
/RA/
Timothy J. McGinty, Director Division Policy and Rulemaking Office of Nuclear Reactor Regulation Technical Contacts: Joshua Palotay Roger Pedersen
(301) 415-6231 (301) 415-3162 E-mail: Joshua.Palotay@nrc.gov E-mail: Roger.Pedersen@nrc.gov Enclosure: List of Recently Issued Office of Federal and State Material and Environmental Management Programs Generic Communications
PUBLIC PROTECTION NOTIFICATION
The NRC may not conduct or sponsor, and a person is not required to respond to, a request for information or an information collection requirement unless the requesting document displays a current valid OMB control number.
CONTACT
Please direct any questions about this matter to the technical contact listed below.
/RA by MTschiltz for/ /RA/
Daniel Dorman, Director Robert J. Lewis, Director Division of Fuel Cycle Safety Division of Materials Safety and Safeguards and State Agreements Office of Nuclear Material Safety Office of Federal and State Materials and Safeguards and Environmental Management Programs
/RA/
Timothy J. McGinty, Director Division Policy and Rulemaking Office of Nuclear Reactor Regulation Technical Contacts: Roger Pedersen
(301) 415-3162 E-mail: Roger.Pedersen@nrc.gov Enclosure: List of Recently Issued Office of Federal and State Material and Environmental Management Programs Generic Communications Distribution ADAMS ACCESSION NO. ML082320040 TAC NO. MD9331 OFFICE NRR/IRIB NRR/IRIB Tech Ed NRR/IRIB NRR/DIRS
NAME JPalotay RPedersen email TKobetz FBrown DATE 11/ 03 /08 11/ 03 /08 08/ 27 /08 11/10/08 11/10/08 OFFICE D:NRR/DORL FSME/DMSSA FSME/DMSSA D:FSME/DMSSA D:NMSS/FCSS
NAME JGitter AMcIntosh JDeCico RLewis DDorman DATE 12/ 05/08 11/23/08 11/26/08 12/02/08 11/14/08 OFFICE OGC-NLO OGC-CRA OE NRO PMDA
CCarpenter NHilton NAME BJones JAdler GTracy LHill for DATE 11/25/08 11/17/08 11/14/08 01/ /09 11/10/08 OFFICE OIS LA:PGCB PGCB BC:PGCB D:NRR/DPR
NAME GTrussell CHawes SStuchell MMurphy TMcGinty DATE 11/17/08 06/10/09 06/11/09 07/06/09 07/13/09 OFFICIAL RECORD COPY List of Recently Issued Office of Federal and State Material and Environmental Management Programs Generic Communications Date GC No. Subject
Addressees
05/13/08 RIS-2008-10 Notice Regarding Forthcoming All U.S. Nuclear Regulatory Commission Federal Firearms Background licensees, certificate holders, and Checks applicants for a license or certificate of compliance who use armed security personnel as part of their physical protection system and security organization. All Radiation Control Program Directors and State Liaison Officers.
05/12/08 RIS-2008-11 Precautions to Protect Children Who All U.S. Nuclear Regulatory Commission May Come in Contact with Patients medical-use licensees, master material Released After Therapeutic licensees, Agreement State Radiation Administration of Iodine-131 Control Program Directors, and State Liaison Officers
05/09/08 RIS-2008-12 Considerations for Extended Interim All holders of U.S. Nuclear Regulatory Storage of Low-level Radioactive Commission fuel cycle and materials Waste by Fuel Cycle and Materials licenses. All Radiation Control Program Licensees Directors and State Liaison Officers
06/16/08 RIS-2008-13 Status And Plans for Implementation All U.S. Nuclear Regulatory Commission of NRC Regulatory Authority for materials licensees, Radiation Control Certain Naturally Occurring and Program Directors, State Liaison Officers, Accelerator-Produced Radioactive and the NRCs Advisory Committee on the Material Medical Uses of Isotopes
07/18/08 RIS-2008-17 Voluntary Security Enhancements All U.S. Nuclear Regulatory Commission for Self-Contained Irradiators Materials Licensees Authorized to Possess Containing Cesium Chloride Self-Contained Irradiators Containing Sources Cesium Chloride (CsCl) ; all Agreement State Radiation Control Program Directors and State Liaison Officers; all members of the Advisory Committee on the Medical Uses of Isotopes.
05/16/08 IN-2008-03 Precautions to Take Before Sharing All U.S. Nuclear Regulatory Commission Sensitive Security-Related licensees who are implementing U.S.
Information Nuclear Regulatory Commissions Order Imposing Increased Controls (IC Order) or implementing IC requirements by license condition; all Agreement State Radiation Control Program Directors and State Liaison Officers Note: This list contains the six most recently issued generic communications, issued by the Office of Federal and State Materials and Environmental Management Programs (FSME). A full listing of all generic communications may be viewed at the NRC public website at the following address: http://www.nrc.gov/reading-rm/doc- collections/gen-comm/index.html