Voluntary Adoption of Revised Design Basis Accident Dose Criteria

NUCLEAR REGULATORY COMMISSION <CFR>10 CFR Part 50</CFR> <DEPDOC>[Docket No. PRM-50-121; NRC-2020-0055]</DEPDOC> <SUBJECT>Voluntary Adoption of Revised Design Basis Accident Dose Criteria</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Nuclear Regulatory Commission. <HD SOURCE="HED">ACTION:</HD> Petition for rulemaking; denial. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The U.S. Nuclear Regulatory Commission (NRC) is denying a petition for rulemaking, dated November 23, 2019, submitted by John G. Parillo. The petition requested that the NRC develop a rule that would allow nuclear power plant licensees to voluntarily adopt a revised accident dose acceptance criteria for the control room, exclusion area boundary, and the low population zone outer boundary. The petition further requested revisions to clarify footnotes discussing these dose acceptance criteria in the applicable regulations. The NRC docketed the petition on February 19, 2020, and assigned it Docket No. PRM-50-121. The NRC is denying the petition because the information presented does not support rulemaking and the proposed changes are not necessary to provide reasonable assurance of adequate protection of public health and safety. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> The docket for the petition for rulemaking PRM-50-121 is closed on July 28, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Please refer to Docket ID NRC-2020-0055 when contacting the NRC about the availability of information for this action. You may obtain publicly available information related to this action by any of the following methods: • <E T="03">Federal Rulemaking website:</E> Go to <E T="03">https://www.regulations.gov</E> and search for Docket ID NRC-2020-0055. Address questions about NRC dockets to Helen Chang; telephone: 301-415-3228; email: <E T="03">Helen.Chang@nrc.gov.</E> For technical questions, contact the persons listed in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section of this document. • <E T="03">NRC's Agencywide Documents Access and Management System (ADAMS):</E> You may obtain publicly available documents online in the ADAMS Public Documents collection at <E T="03">https://www.nrc.gov/reading-rm/adams.html.</E> To begin the search, select “Begin Web-based ADAMS Search.” For problems with ADAMS, please contact the NRC's Public Document Room (PDR) reference staff at 1-800-397-4209, at 301-415-4737, or by email to <E T="03">PDR.Resource@nrc.gov.</E> For the convenience of the reader, instructions about obtaining materials referenced in this document are provided in the “Availability of Documents” section of this document. • <E T="03">NRC's PDR:</E> You may examine and purchase copies of public documents by appointment at the NRC's PDR, Room P1 B35, One White Flint North, 11555 Rockville Pike, Rockville, Maryland 20852. To make an appointment to visit the PDR, please send an email to <E T="03">PDR.Resource@nrc.gov</E> or call 1-800-397-4209 or 301-415-4737, between 8 a.m. and 4 p.m. eastern time, Monday through Friday, except Federal holidays. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Elijah Dickson, Office of Nuclear Reactor Regulation, telephone: 301-415-7647, email: <E T="03">Elijah.Dickson@nrc.gov</E> or Tyler Hammock, Office of Nuclear Material Safety and Safeguards, telephone: 301-415-1381, email: <E T="03">Tyler.Hammock@nrc.gov.</E> Both are employees of the U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001. </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">I. The Petition</HD> Section 2.802 of title 10 of the <E T="03">Code of Federal Regulations</E> (10 CFR), “Petition for rulemaking—requirements for filing,” provides an opportunity for any interested person to petition the Commission to issue, amend, or rescind any regulation. On November 23, 2019, the NRC received a petition for rulemaking (PRM) from John G. Parillo. The petition requested that the NRC develop a rule allowing licensees to voluntarily adopt a revised dose acceptance criteria of 10 rem total effective dose equivalent (TEDE) for the control room, the exclusion area boundary, and the low population zone. The petitioner identified concerns with the current acceptance ( <E T="03">i.e.,</E> dose) criteria in 10 CFR part 100, “Reactor Site Criteria,” § 100.11, “Determination of exclusion area, low population zone, and population center distance,” its basis document, Technical Information Document (TID)-14844, “Calculation of Distance Factors for Power and Test Reactor Sites,” United States Atomic Energy Commission, March 23, 1962, and the alternate accident source term requirements in 10 CFR part 50, “Domestic Licensing of Production and Utilization Facilities,” § 50.67, “Accident source term.” Additionally, this petition examined the objectives of the control room design criterion in 10 CFR part 50, appendix A, “General Design Criteria for Nuclear Power Plants,” criterion 19, “Control Room,” and the relationship between the control room design criterion and the reactor site criteria. The petitioner also identified concerns with the translation of the § 100.11 dose criteria (25 rem whole body and 300 rem thyroid) into the single 25 rem dose criterion used in other regulations, including requirements applicable to: (1) construction permit applicants under § 50.34(a); (2) applicants under 10 CFR part 52, “Licenses, Certification, and Approvals for Nuclear Power Plants;” and (3) licensees of operating nuclear power plants originally licensed prior to January 10, 1997, who seek to revise their accident source term under § 50.67. With regard to these regulations, applicants must demonstrate that the following radiological acceptance criteria are met: (1) an individual located on any point on the boundary of the exclusion area for any 2-hour period following the onset of postulated fission product release would not receive a radiation dose in excess of 0.25 sievert (Sv) (25 rem) TEDE; (2) an individual located at any point on the outer boundary of the low population zone, who is exposed to the radioactive cloud resulting from the postulated fission product release (during the entire period of its passage), would not receive a radiation dose in excess of 0.25 Sv (25 rem) TEDE; and (3) adequate radiation protection is provided to permit access to, and occupancy of, the control room under accident conditions without personnel receiving radiation exposures in excess of 0.05 Sv (5 rem) TEDE for the duration of the accident. For the purposes of this document, “siting criteria” refers to the 0.25 Sv (25 rem) exclusion area boundary and low population zone TEDE criteria, and the “control room design criterion” refers to the 0.05 Sv (5 rem) control room TEDE criterion. The NRC identified three unique categories of petitioned changes within PRM-50-121: (1) voluntary rule development; (2) conforming changes to Regulatory Guide (RG) 1.183, “Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors” (ML003716792); and (3) other petitioned changes, which include proposed changes to footnotes. <HD SOURCE="HD2">Voluntary Rule Development</HD> The petition requested that the NRC develop a rule that would allow licensees to voluntarily adopt a revised accident dose acceptance criterion of 0.1 Sv (10 rem) TEDE for the three criteria in § 50.67(b)(2). The petition stated that the voluntary rule would be reflective of modern health physics recommendations and modern plant designs. The petition stated that NRC's design basis accident (DBA) dose criteria and the resulting design of accident mitigation systems could be perceived to emphasize protection of the control room operator over protection of the public. Further, the petition stated that the proposed change would provide a better balance between protection of the control room operators and the protection of the public. The petition also noted that the control room design criterion has proven to be challenging to demonstrate because most nuclear power plants have minimal margin to the 0.05 Sv (5 rem) TEDE regulatory criterion contained in § 50.67(b)(2)(iii). The petition claimed that a uniform criterion of 0.1 Sv (10 rem) TEDE in a new § 50.67a would relieve the current regulatory burden associated with meeting the current control room design criterion for current operating nuclear power plants. Therefore, the petition also recommended conforming changes to General Design Criterion (GDC) 19 of appendix A to 10 CFR part 50 to permit the use of a 0.1 Sv (10 rem) TEDE control room design criterion if a 0.1 Sv (10 rem) TEDE criterion for the alternate source-term siting criterion was voluntarily adopted. <HD SOURCE="HD2">Proposed Changes to Regulatory Guide 1.183</HD> The petition suggested that RG 1.183 be revised to align with the regulations in new § 50.67a, as proposed by the petition. <HD SOURCE="HD2">Other Petitioned Changes</HD> The petition proposed several revisions to footnotes to 10 CFR parts 50, 52, and 100. First, the petition suggested that the NRC remove references to the National Bureau of Standards (NBS) Handbook 69, “Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and in Water for Occupational Exposure,” in 10 CFR parts 50, 52, and 100 ( <E T="03">i.e.,</E> §§ 50.34, 52.17, 52.47, 52.79, 52.137, 52.157, and 100.11) based on the petition's assertion that the NBS Handbook 69 is outdated, conflicts with 10 CFR part 20, “Standards for Protection Against Radiation,” and was only intended to be used for a once-in-a-lifetime accidental or emergency dose to radiation workers. Second, the petition stated that there are inconsistencies between the terms “whole-body dose” and “total effective dose equivalent,” describing the 0.25 Sv (25 rem) criterion in current regulations ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 30k characters. 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