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MONTHYEARDCL-08-050, and Humboldt Bay Power Plant, Unit 3, Application to Use Weighting Factors for Effective Dose Equivalent2008-06-0909 June 2008 and Humboldt Bay Power Plant, Unit 3, Application to Use Weighting Factors for Effective Dose Equivalent Project stage: Request ML0829500802008-10-20020 October 2008 E-mail, Humbolt and Diablo Canyon Rais for Use of Weighting Factors for Ede Project stage: RAI DCL-08-099, Response to Request for Additional Information, Application to Use Weighting Factors for Effective Dose Equivalent2008-11-18018 November 2008 Response to Request for Additional Information, Application to Use Weighting Factors for Effective Dose Equivalent Project stage: Response to RAI ML0834305172008-12-0505 December 2008 Humbold Bay, Unit 3, Weighting Factors RAI Response, SE Input Project stage: RAI ML0834304892008-12-0505 December 2008 Humbold Bay, Unit 3, Weighting Factors RAI Response Email Project stage: RAI ML0834500352008-12-22022 December 2008 Humbolt Bay Power Plant, Unit 3 - Approval to Use Effective Dose Equivalent Weighting Factors for External Radiation Exposure Project stage: Other 2008-12-22
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Category:Letter
MONTHYEARIR 05000275/20230042024-02-0909 February 2024 Integrated Inspection Report 05000275/2023004 and 05000323/2023004 DCL-24-010, Nuclear Material Transaction Report for New Fuel2024-01-29029 January 2024 Nuclear Material Transaction Report for New Fuel ML24002B1802024-01-29029 January 2024 LRA Audit Plan ML24018A0152024-01-29029 January 2024 License Renewal Application Review Schedule Letter ML24012A0552024-01-24024 January 2024 Letter to J. Polanco, Shpo, on Request to Initiate Section 106 Consultation and Scooping Process for the Environmental Review of Diablo Canyon Nuclear Plant, Unit 1 and 2 License Renewal Application ML24012A1582024-01-24024 January 2024 Letter to Hon. Violet Sage Walker, Chairwoman Northern Chumash Tribal Council on Section 106 Consultation and Scoping Process for the Environmental Review of Diablo Canyon Nuclear Plant, Unit 1 and 2 License Renewal Application ML24012A0362024-01-24024 January 2024 Request to Initiate Section 106 Consultation and Scoping Process for the Environmental Review License Renewal Application ML24012A0062024-01-24024 January 2024 Achp Scoping Letter for Diablo Canyon License Renewal ML24003A8902024-01-24024 January 2024 Letter to P. Gerfen - Diablo Canyon Notice of Intent to Conduct Scoping and Prepare an Environmental Impact Statement ML24017A2492024-01-24024 January 2024 Letter to Neil Peyron, Chairman, Tule River Tribe, Re. Diablo Canyon ML24024A1562024-01-24024 January 2024 Letter to Hon. Gabe Frausto, Coastal Band of Chumash Indians on Section 106 Consultation and Scoping Process for the Environmental Review of Diablo Canyon Nuclear Plant, Unit 1 and 2 License Renewal Application ML24024A1752024-01-24024 January 2024 Letter to Tribal Council San Luis Obispo County Chumash Indians on Section 106 Consultation and Scoping Process for the Environmental Review of Diablo Canyon Nuclear Plant, Unit 1 and 2 License Renewal Application ML24024A1652024-01-24024 January 2024 Letter to Hon. Mona Olivas Tucker, Yak Tityu Tityu Yak Tilhini Northern Chumas Indians on Section 106 Consultation and Scoping Process for the Environmental Review of Diablo Canyon Nuclear Plant, Unit 1 and 2 License Renewal Application ML24024A1612024-01-24024 January 2024 Letter Hon. Gary Pierce, Salian Tribe of Monterey and San Luis Obispo Counties on Section 106 Consultation and Scoping Process for the Environmental Review of Diablo Canyon Nuclear Plant, Unit 1 and 2 License Renewal Application DCL-24-009, Nuclear Material Transaction Report for New Fuel2024-01-17017 January 2024 Nuclear Material Transaction Report for New Fuel DCL-24-008, Schedule Considerations for Review of the DCPP License Renewal Application2024-01-17017 January 2024 Schedule Considerations for Review of the DCPP License Renewal Application DCL-24-004, Supplement to License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b2024-01-15015 January 2024 Supplement to License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b IR 05000275/20230112024-01-12012 January 2024 NRC License Renewal Phase 1 Inspection Report 05000275/2023011 DCL-23-129, Nuclear Material Transaction Report for New Fuel2023-12-27027 December 2023 Nuclear Material Transaction Report for New Fuel ML23326A0122023-12-21021 December 2023 12-21-23 Letter to the Honorable Byron Donalds from Chair Hanson Responds to Letter Regarding 2.206 Petition to Close Diablo Canyon Nuclear Power Plant, Unit 1 ML23341A0042023-12-19019 December 2023 LRA Acceptance Letter ML23352A2342023-12-18018 December 2023 Notification of Age-Related Degradation Inspection (05000275/2024014 and 05000323/2024014) and Request for Information DCL-23-122, Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2023-12-14014 December 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation DCL-23-128, Emergency Plan Update2023-12-13013 December 2023 Emergency Plan Update ML23355A0952023-12-0808 December 2023 License Renewal Application Online Reference Portal DCL-23-125, Core Operating Limits Report for Unit 1 Cycle 252023-12-0606 December 2023 Core Operating Limits Report for Unit 1 Cycle 25 L-23-009, Independent Spent Fuel Storage Installation, Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2023-12-0404 December 2023 Independent Spent Fuel Storage Installation, Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation ML23320A2442023-11-28028 November 2023 Letter to Kerri Vera, Director of Department of Environmental Protection, Tule River Tribe; Re., Diablo Canyon ISFSI Initiating Section 106 Consultation ML23291A2702023-11-28028 November 2023 Letter to Nakia Zavalla, Shpo, the Santa Ynez Band of Chumash Indians; Re., Diablo Canyon ISFSI Initiating Section 106 Consultation ML23325A1292023-11-27027 November 2023 ISFSI Tribal Letter to Coastal Band of Chumash ML23325A1322023-11-27027 November 2023 ISFSI Tribal Letter to Salian Tribe of Montgomery, San Luis Obispo ML23325A1332023-11-27027 November 2023 ISFSI Tribal Letter to Yak Tityu Tityu Northern Chumash Indians ML23325A1382023-11-27027 November 2023 ISFSI Tribal Letter to San Luis Obispo County Chumash Indians ML24003A7242023-11-27027 November 2023 Independent Safety Committee; Diab Lo Canyon Nuclear Power Plant Operations, Thirty-Third Annual Report on the Safety ML23307A0062023-11-27027 November 2023 ISFSI Tribal Letter to Northern Chumash Tribal Council ML23320A1502023-11-17017 November 2023 Individual Notice of Consideration of Issuance of Amendment to Facility Operating License, Proposed No Significant Hazards Consideration Determination, & Opportunity for Hearing (Exigent Circumstances) (EPID L-2023-LLA-0155) - LTR DCL-23-121, Supplement to License Amendment Request 23-03, Revision to Technical Specification3.7.8, Auxiliary Saltwater System2023-11-16016 November 2023 Supplement to License Amendment Request 23-03, Revision to Technical Specification3.7.8, Auxiliary Saltwater System ML23296A0982023-11-15015 November 2023 Notification and Request for Consultation Regarding Pacific Gas and Electric Diablo Canyon Independent Spent Fuel Storage Installation Material License Renewal Request (Docket Number: 72-26) DCL-23-120, License Amendment Request 23-03 Revision to Technical Specification 3.7.8, Auxiliary Saltwater (Asw) System2023-11-14014 November 2023 License Amendment Request 23-03 Revision to Technical Specification 3.7.8, Auxiliary Saltwater (Asw) System ML23293A1052023-11-14014 November 2023 Receipt and Availability of License Renewal Application IR 05000275/20230032023-11-13013 November 2023 Integrated Inspection Report 05000275/2023003 and 05000323/2023003 ML23311A2082023-11-0909 November 2023 Reassignment of U.S. Nuclear Regulatory Commission Branch Chief in the Division of Operating Reactor Licensing for Plant Licensing Branch IV DCL-23-118, License Renewal Application2023-11-0707 November 2023 License Renewal Application ML23318A2102023-10-31031 October 2023 Independent Safety Committee; Thirty-Third Annual Report on the Safety of Diablo Canyon Nuclear Power Plant Operations DCL-2023-520, Discharge Self-Monitoring at Diablo Canyon Power Plant (DCPP)2023-10-19019 October 2023 Discharge Self-Monitoring at Diablo Canyon Power Plant (DCPP) DCL-23-103, Independent Spent Fuel Storage Installation - Withdrawal of License Amendment Request 22-01, Request for Approval of Alternative Security Measures for Early Warning System2023-10-13013 October 2023 Independent Spent Fuel Storage Installation - Withdrawal of License Amendment Request 22-01, Request for Approval of Alternative Security Measures for Early Warning System 2024-02-09
[Table view] Category:Safety Evaluation
MONTHYEARML23199A3122023-07-20020 July 2023 Revision to the Reactor Vessel Material Surveillance Capsule Withdrawal Schedule ML22340A6752023-03-0606 March 2023 Approval of Certified Fuel Handler Training and Retraining Program ML23012A2172023-02-0909 February 2023 Issuance of Amendment Nos. 244 and 245 Revision to Technical Specifications to Adopt TSTF-569, Revision 2, Revise Response Time Testing Definition ML21242A2162022-12-21021 December 2022 Issuance of Amendment Nos. 243 and 244 Technical Specifications and Revised License Conditions for the Permanently Defueled Condition (EPID: L-2020-LLA-0261 ML22334A0822022-12-0101 December 2022 Correction to Issuance of Amendment Nos. 242 and 243 Revision to Emergency Plan for Post-Shutdown and Permanently Defueled Condition ML22187A0252022-11-16016 November 2022 Issuance of Amendment Nos. 242 and 243 Revision to Emergency Plan for Post-Shutdown and Permanently Defueled Condition ML22221A1682022-09-0606 September 2022 Issuance of Amendment Nos. 241 and 242 Revision to Technical Specifications to Adopt TSTF-577, Revised Frequencies for Steam Generator Tube Inspection ML21160A1742021-09-0202 September 2021 Issuance of Amendment Nos. 239 and 240 Revising Technical Specification 3.2.1, Heat Flux Hot Channel Factor (Fq(Z)), to Implement Methodology from WCAP-17661, Revision 1 ML21214A1002021-08-0303 August 2021 Letter to J. Welsch, Pg&E, from A. Snyder, NRC, Humboldt Bay Power Plant, Unit 3 - Approval of Final Status Survey Reports for Caisson Survey Units NOL01-09/NOL01-09-FSR ML21214A1012021-08-0303 August 2021 Enclosure - Humboldt Bay Power Plant, Unit 3 - Approval of Final Status Survey Reports for Caisson Survey Units NOL01-09/NOL01-09-FSR Safety Evaluation Report ML21188A3452021-07-0808 July 2021 Issuance of Amendment No. 238 Revision to TS 3.7.8, Auxiliary Saltwater (Asw) System (Emergency Circumstances) ML20249C8502020-10-22022 October 2020 Proposed Alternative NDE-RCS-SE-2R22 to the Requirements of the ASME Code ML20218A2762020-09-11011 September 2020 Issuance of Amendment Nos. 237 and 239 to Relocate Technical Specification 5.3, Unit Staff Qualifications, to Updated Final Safety Analysis Report ML20235R6352020-08-31031 August 2020 Issuance of Amendment Nos. 236 and 238 Revision to Technical Specification 3.7.5, Auxiliary Feedwater (AFW) System, Exigent Circumstances ML20030A1002020-02-12012 February 2020 Approval Safety Evaluation for Six Survey Areas within Survey Unit OOL10 ML19319B0632019-12-0404 December 2019 SER Humboldt Bay Power Plant, Unit 3 - Approval of Final Status Survey Reports for the Relay Building and the Mepps Island Building ML19274B0822019-10-0707 October 2019 Correction to Issuance of Amendment Nos. 233 and 235 to Revise the Emergency Plan to Change Staffing and Extend Staff Augmentation Times for ERO Positions ML19196A3092019-08-21021 August 2019 Issuance of Amendment Nos. 233 and 235 Regarding Revision to Emergency Plan to Change Staffing and Extend Staff Augmentation Times for Emergency Response Organization Positions ML19176A0082019-06-28028 June 2019 Request for Relief from the Inservice Inspection Program Requirements of ASME Code, Section XI, for Steam Generator and Pressurizer Nozzle Inside Radius Sections ML19023A0262019-01-25025 January 2019 Request for Alternative from Volumetric/Surface Examination Frequency Requirements of ASME Code Case N-729-4 ML18278A0872018-10-11011 October 2018 Letter to Halpin, Humboldt Bay Power Plant, Unit 3 - Approval of Final Status Survey Reports OOL10-04 and ISF01-01 ML17115A1092018-01-0505 January 2018 Safety Evaluation by Office of Nuclear Material Safety and Safeguards Related to the Release of Land from Facility Operating License No. DPR-7 Pacific Gas and Electric Company Humboldt Bay Power Plant Unit 3 (Docket 50-133) ML17263A0592017-10-0606 October 2017 Diablo Canyon Power Plant, Unit 2 - Relief Requests to Allow Use of Proposed Alternatives to Implement Requirements of ASME Code, for Reactor Pressure Vessel Welds for the Third ISI Interval (CAC Nos. MF9386, MF9387, MF9388, MF9389, and MF9390) ML17212A3792017-09-25025 September 2017 Diablo Canyon Power Plant, Units 1 and 2 - Issuance of Amendment Nos. 231 and 233 Re: Emergency Action Level Scheme Change (CAC Nos. MF8528 and MF8529) ML17132A2312017-05-16016 May 2017 Diablo Canyon Power Plant, Units 1 and 2 - Correction Letter Regarding Amendment Nos. 230 and 232 to Adopt Alternative Source Term (CAC Nos. MF6399 and MF6400) ML17012A2462017-04-27027 April 2017 Issuance of Amendments Revise Licensing Bases to Adopt Alternative Source Term ML17037D2672017-03-0909 March 2017 Relief Request NDE-RCS-SE-1R20 to Allow Use of Alternate Depth Sizing Criteria for the Fourth Inservice Inspection ML17018A3412017-02-23023 February 2017 Issuance of Amendments Revise Technical Specification 3.4.12, Low Temperature Overpressure Protection (LTOP) System, ML16349A3862016-12-28028 December 2016 Safety Evaluation Regarding Implementation of Mitigating Strategies and Reliable Spent Fuel Pool Instrumentation Related to Orders EA-12-049 and EA-12-051 ML16139A0082016-12-21021 December 2016 Issuance of Amendment Nos. 227 and 229, Digital Replacement of the Process Protection System Portion of the Reactor Protection System and Engineered Safety Features Actuation System ML16207A3972016-07-27027 July 2016 Relief Request NDE-SIF-U1, Allow Use of Alternate Examination Volume Coverage Requirements, Class 2 Seal Injection Welds, for the Third 10-Year Inservice Inspection Interval ML16117A2522016-05-19019 May 2016 Issuance of Amendment Nos. 226 and 228, Revise Minimum Flow Value Specified in Technical Specification 3.4.1, RCS Pressure, Temperature, and Flow Departure from Nucleate Boiling (DNB) Limits ML15090A3392016-05-0404 May 2016 Letter to Halpin, Amendment to Humboldt Bay License Approving the License Termination Plan ML16035A4412016-04-14014 April 2016 Issuance of Amendment Nos. 225 and 227, Adopt National Fire Protection Association NFPA 805, Performance-Based Standard for Fire Protection for LWR Generating Plants (2001 Edition) ML16055A3592016-03-0909 March 2016 Issuance of Amendment Nos. 224 and 226, Revise Updated Final Safety Analysis Report for Beacon Power Distribution Monitoring System Methodology and TS 5.6.5 (COLR) Paragon and Nexus Methodologies ML16056A5132016-03-0707 March 2016 Relief Request FLIG-U1, Request to Extend Third 10-Year Inservice Inspection Interval for Reactor Vessel Stud Hole Ligament Examinations ML16055A2812016-02-26026 February 2016 Relief Request NDE-FWNS-U1/U2 to Allow Use of Alternate Examination Volume Coverage Requirements, Third 10-Year Inservice Inspection Interval ML16032A0062016-02-19019 February 2016 Redacted, Issuance of Amendment Nos. 223 and 225, Revise UFSAR Section 15.4.2.2 to Incorporate Pressurizer Filling Analysis for Major Rupture of a Main Feedwater Pipe Accident Into Licensing Basis ML16013A3402016-01-27027 January 2016 Relief Request NDE-PNS-U2A, ASME Code Section XI Requirements to Allow Use of Alternate Exam Volume Coverage Requirements, for the Third 10-year Inservice Inspection Interval ML15037A0062016-01-0505 January 2016 ISFSI - Safety Evaluation, Encl. 4, Amendment Nos. 222, 224, and 4 - Authorize Use of Preemption Authority Granted Under Provisions of Section 161A of the Atomic Energy Act of 1954, as Amended (CAC MF2809, MF2810, and L24991) ML15029A1732016-01-0505 January 2016 ISFSI - Issuance of Amendment Nos. 222, 224, and 4, Authorize Use of Preemption Authority Granted Under Provisions of Section 161A of the Atomic Energy Act of 1954, as Amended (CAC MF2809, MF2810, and L24991) ML15337A0212015-12-0808 December 2015 Relief Request NDE-SG-MS-IR - Relief from Exam Requirements for Main Steam Nozzles in Replacement Steam Generators, Third 10-Year Inservice Inspection Interval ML15281A1642015-12-0303 December 2015 Issuance of Amendment Nos. 221 and 223, Revise Updated Final Safety Analysis Report and Approval to Perform Fuel Assembly Structural Analyses That Considers Application of Leak Before Break ML15299A0342015-11-0404 November 2015 Relief Request NDE-RCS-SE-2R19, Use of Alternate Sizing Qualification Criteria Through a Protective Clad Layer, Third 10-Year Inservice Inspection Interval ML15245A5422015-09-30030 September 2015 Issuance of Amendment Nos. 220 and 222, Request to Revise Operating License Condition Related to Cyber Security Plan Milestone H Full Implementation Date ML15148A3612015-09-23023 September 2015 Letter to E. Halpin Issuance of Amendment 46 for Humboldt Bay Emergency Plan ML15261A0072015-09-18018 September 2015 Request for Relief PRS-3, Proposed Alternative to Requirements for System Leakage Testing Class 1 Piping Vent, Drain, and Test Isolation Devices, for the Third 10-year Inservice Inspection Interval (TAC MF6520-MF6521) ML15204A2222015-08-27027 August 2015 Issuance of Amendment Nos. 219 and 221, Adopt Technical Specifications Task Force Traveler TSTF-432, Revision 1, Change in Technical Specification End States (WCAP-16294) ML15187A0352015-07-15015 July 2015 Relief Request REP-SI, Revision 2, Proposed Alternative for Repair/Replacement Activities for Certain Safety Injection Pump Welded Attachments, Remaining Useful Life +20 Years ML15162A8822015-07-0101 July 2015 Issuance of Amendment Nos. 218 and 220, Revise Surveillance Requirements in TS 3.8.1, AC Sources, Related to Diesel Generator Testing 2023-07-20
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 December 22, 2008 Mr. John Conway Senior Vice President - Station Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 770000 San Francisco, CA 94177-0001
SUBJECT:
DIABLO CANYON POWER PLANT, UNITS NOS. 1 AND 2, AND HUMBOLT BAY POWER PLANT, UNIT 3 - APPROVAL TO USE EFFECTIVE DOSE EQUIVALENT WEIGHTING FACTORS FOR EXTERNAL RADIATION EXPOSURE (TAC NOS. MD8914 AND MD8915)
Dear Mr. Conway:
By the letter dated June 9,2008, as superceded by letter dated November 18,2008, Pacific Gas and Electric Company (PG&E, the licensee) requested approval by the US Nuclear Regulatory Commission (NRC) for the use of the weighting factors listed in Table 1 in the American National Standard Institute (ANSI) HPS N13.41-1997, "Criteria for Performing Multiple Dosimetry," (the Standard) for external radiation exposures when demonstrating compliance with total effective dose equivalent (TEDE), based on requirements in Title 10 of the Code of Federal Regulations (10 CFR), Part 20, for the Diablo Canyon Power Plant, Unit Nos. 1 and 2, and Humboldt Bay Power Plant, Unit 3.
This approval allows the licensee the option to control effective dose equivalent (EDE) using the weighted external exposure measurements, in those cases, where it is a more accurate predictor of the risk from occupational radiation exposure.
The NRC staff completed a technical and regulatory review of the proposed request and supporting documentation. The NRC staff concludes that the licensee's commitments to dose measurement using the multiple dosimetry method to determine EDE from external exposures (EDE ex ) by applying the weighting factors listed in Table 1 of ANSI/HPS N13.41-1997 is consistent with the ANSI/HPS standard and with the requirements of 10 CFR, Part 20, and is therefore acceptable for the purposes of demonstrating compliance with the TEDE based requirements in 10 CFR, Part 20.
J. Conway -2 The basis for the NRC staff conclusion is contained in the attached safety evaluation. If you have any questions, please contact me at 301-415-1445 or bye-mail at Alan.Wang@nrc.gov.
Sincerely,
();m WOJ1 .
Alan Wang, Project Plant Licensing
~~
Bran~tJ~ger Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-275, 50-323 and 50-133
Enclosure:
Safety Evaluation cc w/encl: Distribution via ListServ
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO APPROVAL TO USE EFFECTIVE DOSE EQUIVALENT WEIGHTING FACTORS FOR EXTERNAL RADIATION EXPOSURE PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON POWER PLANT, UNITS 1 & 2, AND HUMBOLDT BAY POWER PLANT, UNIT 3 DOCKET NOS. 50-275, 50-323, AND 50-133
1.0 INTRODUCTION
By the letter dated June 9, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML081700090), as superseded by letter dated November 18, 2008 (ADAMS Accession No. ML083370178), Pacific Gas and Electric Company (the licensee) requested approval by the U.S. Nuclear Regulatory Commission (NRC) for the use of the weighting factors listed in Table 1 in the American National Standard Institute (ANSI) HPS N13.41-1997, "Criteria for Performing Multiple Dosimetry," (the Standard) for external radiation exposures when demonstrating compliance with total effective dose equivalent (TEDE), based on requirements in Title 10 of the Code of Federal Regulations (10 CFR) Part 20, for the Diablo Canyon, Units 1 and 2, and the Humboldt Bay Power Plant, Unit 3. The Standard was approved in December 1996 by the NRC.
The licensee stated that accurate assessment of occupational exposure of workers from external sources of radiation in highly non-uniform radiation fields requires a method for assessing the effective dose equivalent (EDE) and that the use of the proposed weighting factors will improve the accuracy of the licensee's assessment of occupational exposure.
Therefore, the effect of granting this request would be to allow the licensee the option to control EDE using the weighted external exposure measurements in those cases where it is a more accurate predictor of the risk from occupational radiation exposure.
2.0 REGULATORY EVALUATION
The requirements for demonstrating compliance with TEDE dose limits are provided in 10 CFR 20.1201 (c). The regulations define Effective Dose Equivalent (EDE or HE) as Ii the sum of the products of the dose equivalent to the organ or tissue (HT) and the weighting factors (cuT)
=
applicable to each of the body organs or tissues that are irradiated (HE ~cuTHT)." Each tissue weighting factor is the proportion of the risk of stochastic effects resulting from the dose to that organ or tissue to the total risk of stochastic effects when the whole body is irradiated uniformly.
The weighting factors are applicable to the organs and tissues whether the dose results from radiation sources internal or external to the body.
-2 For the purposes of implementing workplace controls, and due to the difference in dosimetry methods, Part 20 breaks EDE into two components: dose resulting from radioactive sources internal to the body, and dose resulting from sources external to the body. The doses from external and internal exposures are then summed to obtain the TEDE. Several dose limits (such as those in 10 CFR 20.1201 (a)(1 )(i) and 20.1301 (a)) and other requirements in Part 20 are based on TEDE.
As of February 15, 2008, 10 CFR 20.1003 defines TEDE as the "sum of the effective dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures)." The committed effective dose equivalent is the sum of the products of the dose equivalents to each tissue, from radioactive material taken into the body, integrated over 50 years, and the weighting factor applicable to that tissue.
In most relatively uniform exposure situations, a single dosimeter, calibrated to measure Deep Dose Equivalent (DDE), worn on the whole body, provides a reasonably accurate estimate of the EDE from external exposures (EDE ex ). If the body is not irradiated uniformly, a single dose measurement cannot determine the dose to the various organs and tissues for an accurate determination of the EDE ex . To insure a conservative TEDE determination, 10 CFR 20.1201 (c) requires that when external exposure is determined by measurement with an external monitoring device, the DDE, measured for the part of the body receiving the highest exposure, must be used in place of the EDE ex , unless the EDE ex is determined by a dosimetry method approved by the NRC.
Using DDE in place of EDE ex can be overly conservative in extremely non-uniform irradiations (e.g., when only a small portion of the whole body is irradiated). As discussed in NRC Regulatory Issue Summaries 2002-06, 2003-04 and 2004-01, the NRC has approved several methods for determining EDE ex , and has encouraged the use of EDE ex in place of DDE for demonstrating compliance with the TEDE requirements in Part 20.
3.0 TECHNICAL EVALUATION
The NRC staff reviewed the technical approach for estimating EDE ex provided in ANSI/HPS N13.41-1997. This multiple dosimetry method divides the whole body into seven separate compartments. Each compartment, or combined compartment (since the ANSI IHPS N13.41 allows combining adjacent compartments), is monitored separately. The results of the dose measurement for each compartment are weighted with an associated "compartment factor."
The resulting weighted doses are then summed to determine the EDE ex for the whole body. As noted earlier, the Standard was approved by the NRC in December 1996.
The compartment factors are listed in Table 1 of the ANSIIHPS N13.41. The factor for each compartment was developed by summing the stochastic weighting factors given in Part 20 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 was apportioned between the compartments based on the fraction of the total mass of the tissue residing in each, using the information in International Commission on Radiation Protection Publication 23.
Fundamental to the ANSI/HPS N13.41 multiple dosimeter method of determining EDE ex , are the assumptions that 1) the average dose to the tissues in each compartment can be reasonably measured (with one or more dosimeters), and 2) that the dose distribution across the
-3 compartment is sufficiently constant so that this average dose can be applied to each tissue in the compartment. The compartments defined in ANSI/HPS N13.41 are small enough so that under most exposure situations these assumptions are met and a single determination of DOE in each compartment is sufficient. However, this may not be the case in those unusual situations where a significant dose gradient exists across the compartment (particularly the thorax and abdomen compartments). In these cases, dosimeter placement, in each compartment becomes critical to ensuring that the EDEex is not underestimated.
The licensee stated in its application that in uniform radiation fields, the dosimeter used to measure whole body dose is normally worn on the chest. To ensure that the estimates of EDEex are conservative, the licensee stated in its application that the dose to each compartment (and/or combined compartment) would be measured by locating the dosimeter, calibrated to DOE, at the highest exposed portion of that compartment, consistent with the dosimeter placement criteria in NRC Inspection Procedure 71121.01.
4.0 CONCLUSION
S The NRC staff concludes that the licensee's commitment to dose measurement using the multiple dosimetry method to determine EDE ex by applying the weighting factors listed in Table 1 of ANSI/HPS N13.41-1997, as discussed above in Section 3.0 of this safety evaluation, is consistent with the ANSI/HPS standard and with the requirements of 10 CFR Part 20, and is therefore acceptable for the purposes of demonstrating compliance with the TEDE based requirements in 10 CFR Part 20.
Principal Contributor: R. Pedersen, NRR Date: December 22, 2008
necember 22, 2008 The basis for the NRC staff conclusion is contained in the attached safety evaluation. If you have any questions, please contact me at 301-415-1445 or bye-mail at Alan.Wang@nrc.gov.
Sincerely, IRAI Alan Wang, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-275, 50-323 and 50-133
Enclosure:
Safety Evaluation cc w/encl: Distribution via ListServ DISTRIBUTION:
PUBLIC RidsNrrDorlLpl4 RPedersen, NRR LPLIV Reading RidsN rrLAG Lappert RidsAcrsAcnwMailCenter RidsN rrPM DiabloCanyon RidsNrrDirsltsb RidsOgcRp RidsNrrDorlDpr RidsRgn4MailCenter ADAMS Accession Nos.: ML083450035 *Concurrence via email OFFICE NRR/LPL4/PM NRR/LPL4/LA NAME GLappert*
DATE 12/10108