STP Nuclear Operating Company; South Texas Project, Units 1 and 2, 33161-33165 [2017-15136]

Download as PDF Federal Register / Vol. 82, No. 137 / Wednesday, July 19, 2017 / Notices Note that after you are subscribed to an NRC ListServ, you will receive an email from the NRC indicating which ListServ you have subscribed to, which email address you used to subscribe to that ListServ, and instructions on how you can unsubscribe to that ListServ, if desired. You are responsible for ensuring that the ListServ has your current email address. Dated at Rockville, Maryland this 10th day of July 2017. For the Nuclear Regulatory Commission. Andrea Kock, Deputy Director, Division of Decommissioning, Uranium Recovery and Waste Programs, Office of Nuclear Material Safety and Safeguards. [FR Doc. 2017–15145 Filed 7–18–17; 8:45 am] BILLING CODE 7590–01–P NUCLEAR REGULATORY COMMISSION [Docket No. 72–1; NRC–2017–0103] GE-Hitachi Nuclear Energy Americas, LLC; GE-Hitachi Morris Operation Independent Spent Fuel Storage Installation Nuclear Regulatory Commission. ACTION: License amendment application; issuance. AGENCY: By letter dated February 15, 2017, as supplemented March 9, 2017, and as supplemented June 6, 2017, GEHitachi (GEH) submitted to the Nuclear Regulatory Commission (NRC) a license amendment request (LAR) No. 15, Materials License No. SNM–2500 (LAR 2500–15) for the GEH Facility at Morris, Illinois, in accordance with NRC’s regulations. The amendment provides clarification for the storage of liquid and solid waste treatment products. The amendment requested no changes to the technical or regulatory provisions of the license. The application included adequate justification for the proposed changes. The NRC has approved and issued the amendment in its letter dated June 29th, 2017, along with its safety evaluation report. DATES: July 19, 2017. ADDRESSES: Please refer to Docket ID NRC–2017–0103 when contacting the NRC about the availability of information regarding this document. You may access publicly-available information related to this document using any of the following methods: • Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC–2017–0103. Address questions about NRC dockets to Carol asabaliauskas on DSKBBXCHB2PROD with NOTICES SUMMARY: VerDate Sep<11>2014 18:49 Jul 18, 2017 Jkt 241001 Gallagher; telephone: 301–415–3463; email: Carol.Gallagher@nrc.gov. For technical questions, contact the individual listed in the FOR FURTHER INFORMATION CONTACT section of this document. • NRC’s Agencywide Documents Access and Management System (ADAMS): You may obtain publiclyavailable documents online in the ADAMS Public Documents collection at http://www.nrc.gov/reading-rm/ adams.html. To begin the search, select ‘‘ADAMS Public Documents’’ and then 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, 301–415–4737, or by email to pdr.resource@nrc.gov. The ADAMS accession number for each document referenced (if it is available in ADAMS) is provided the first time that it is mentioned in this document. The GE-Hitachi Morris Operation License Amendment Request No. 15 is available in ADAMS under Accession Nos. ML17046A072, ML17072A381, and ML17157B369, respectively. • NRC’s PDR: You may examine and purchase copies of public documents at the NRC’s PDR, Room O1–F21, One White Flint North, 11555 Rockville Pike, Rockville, Maryland 20852. FOR FURTHER INFORMATION CONTACT: Christian Jacobs, Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, Washington, DC 20555–0001; telephone: 301–415–6825: email: Christian.Jacobs@ nrc.gov. SUPPLEMENTARY INFORMATION: On December 21, 2004, the NRC renewed Special Nuclear Materials License No. SNM–2500 for the GEMO independent spent fuel storage installation (ISFSI) (ADAMS Accession No. ML043630433), located near Morris, Illinois. The renewed license authorizes GE-Hitachi Nuclear Energy Americas, LLC, to possess, store, and transfer spent nuclear fuel and associated radioactive materials at the GEMO ISFSI for a term of 20 years. The NRC also issued an environmental assessment and finding of no significant impact related to the issuance of the renewed ISFSI license on November 30, 2004 (ADAMS Accession No. ML043360409), in accordance with the National Environmental Policy Act, and in conformance with the applicable requirements of part 51 of title 10 of the Code of Federal Regulations (10 CFR). Pursuant to 10 CFR 72.46 and 72.58, the NRC has docketed, approved and issued Amendment No. 15 to Special Nuclear Materials License No. SNM– PO 00000 Frm 00122 Fmt 4703 Sfmt 4703 33161 2500, held by GE-Hitachi Nuclear Energy Americas, LLC, for the possession, transfer and storage of spent fuel at the GEMO ISFSI. Amendment No. 15 is effective as of the date of issuance. Amendment No. 15 complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission’s rules and regulations. The Commission has made appropriate findings, as required by the Act and the Commission’s rules and regulations in 10 CFR chapter 1, which are set forth in Amendment No. 15. The issuance of Amendment No. 15 satisfied the criteria specified in 10 CFR 51.22(c)(10)(v) for a categorical exclusion. Thus, the preparation of an environmental assessment or an environmental impact statement was not required. A Notice of Opportunity to Request a Hearing and to Petition for Leave to Intervene in connection with this action was published in the Federal Register on April 24, 2017 (82 FR 18937). No request for a hearing or petition for leave to intervene was filed following this notice. Dated at Rockville, Maryland, this 12th day of July 2017. For the Nuclear Regulatory Commission. John McKirgan, Chief, Spent Fuel Licensing Branch, Division of Spent Fuel Management, Office of Nuclear Material Safety and Safeguards. [FR Doc. 2017–15146 Filed 7–18–17; 8:45 am] BILLING CODE 7590–01–P NUCLEAR REGULATORY COMMISSION [Docket Nos. 50–498 and 50–499; NRC– 2016–0092] STP Nuclear Operating Company; South Texas Project, Units 1 and 2 Nuclear Regulatory Commission. ACTION: Exemption; issuance. AGENCY: The U.S. Nuclear Regulatory Commission (NRC) is granting exemptions from certain portions of the acceptance criteria for emergency core cooling, and the general design criteria for emergency core cooling, containment heat removal, and atmosphere cleanup for the use of a riskinformed analysis to evaluate the effects of debris in containment following a loss-of-coolant accident (LOCA) for the South Texas Project (STP), Units 1 and 2, located in Matagorda County, Texas, Docket Nos. 50–498 and 50–499, respectively. The exemptions are in response to a request dated June 19, SUMMARY: E:\FR\FM\19JYN1.SGM 19JYN1 33162 Federal Register / Vol. 82, No. 137 / Wednesday, July 19, 2017 / Notices asabaliauskas on DSKBBXCHB2PROD with NOTICES 2013, from the STP Nuclear Operating Company (STPNOC, the licensee) related to STPNOC’s proposed approach to resolve a generic safety concern for pressurized water reactors (PWRs) associated with potential clogging of emergency core cooling and containment spray system strainers during certain design basis events. DATES: The exemption was issued on July 11, 2017. ADDRESSES: Please refer to Docket ID NRC–2016–0092 when contacting the NRC about the availability of information regarding this document. You may obtain publicly-available information related to this document using any of the following methods: • Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC–2016–0092. Address questions about NRC dockets to Carol Gallagher; telephone: 301–415–3463; email: Carol.Gallagher@nrc.gov. For technical questions, contact the individual listed in the FOR FURTHER INFORMATION CONTACT section of this document. • NRC’s Agencywide Documents Access and Management System (ADAMS): You may obtain publiclyavailable documents online in the ADAMS Public Documents collection at http://www.nrc.gov/reading-rm/ adams.html. To begin the search, select ‘‘ADAMS Public Documents’’ and then 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, 301–415–4737, or by email to pdr.resource@nrc.gov. For the convenience of the reader, the ADAMS accession numbers are provided in a table in the ‘‘Availability of Documents’’ section of this document. • NRC’s PDR: You may examine and purchase copies of public documents at the NRC’s PDR, Room O1–F21, One White Flint North, 11555 Rockville Pike, Rockville, Maryland 20852. FOR FURTHER INFORMATION CONTACT: Lisa Regner, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington DC 20555– 0001; telephone: 301–415–1906, email: Lisa.Regner@nrc.gov. SUPPLEMENTARY INFORMATION: I. Background The licensee is the holder of Facility Operating License Nos. NPF–76 and NPF–80, which authorize operation of the STP Units 1 and 2, respectively. The licenses provide, among other things, that the facility is subject to all rules, regulations, and orders of the NRC now or hereafter in effect. The facility VerDate Sep<11>2014 18:49 Jul 18, 2017 Jkt 241001 consists of two PWRs located in Matagorda County, Texas. In 1996, the NRC identified Generic Safety Issue (GSI)-191 associated with the effects of debris accumulation on PWR sump performance during designbasis accidents. As part of the actions to resolve GSI–191, the NRC issued Generic Letter (GL) 2004–02, ‘‘Potential Impact of Debris Blockage on Emergency Recirculation during Design Basis Accidents at Pressurized-Water Reactors,’’ dated September 13, 2004, to holders of operating licenses for PWRs. In GL 2004–02, the NRC staff requested that licensees perform an evaluation of their emergency core cooling systems (ECCS) and containment spray system (CSS) recirculation functions considering the potential for debrisladen coolant to be circulated by the ECCS and the CSS after a LOCA or high energy line break inside containment and, if appropriate, take additional actions to ensure system function. The GL required that licensees provide a written response to the NRC, pursuant to section 50.54(f) of title 10 of the Code of Federal Regulations (10 CFR), describing the results of their evaluation and any modifications made, or planned, to ensure the ECCS and CSS remain functional. II. Request/Action By letter dated June 19, 2013, as supplemented by letters dated August 20, 2015, and April 13, 2016, STPNOC submitted requests for exemptions pursuant to 10 CFR 50.12, ‘‘Specific exemptions,’’ from the requirements of 10 CFR 50.46, ‘‘Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors,’’ and 10 CFR part 50, appendix A, General Design Criterion (GDC) 35, ‘‘Emergency core cooling,’’ GDC 38, ‘‘Containment heat removal,’’ and GDC 41, ‘‘Containment atmosphere cleanup,’’ to use a risk-informed methodology instead of the traditional deterministic methodology, to resolve the concerns associated with GSI–191 and respond to GL 2004–02. Specifically, the licensee requested an exemption from 10 CFR 50.46(a)(1)(i), which, in part, requires ECCS cooling performance to be calculated in accordance with an acceptable evaluation model, as described in 10 CFR 50.46(a)(1), for postulated LOCAs of different sizes, locations and other properties sufficient to provide assurance that the most severe LOCAs are evaluated in order to demonstrate that acceptance criteria in 10 CFR 50.46(b) are met. The NRC staff interprets 10 CFR 50.46(a)(1) requirement to calculate ECCS PO 00000 Frm 00123 Fmt 4703 Sfmt 4703 performance for ‘‘other properties’’ as requiring licensees to consider the impacts of debris generation and transport in containment. The most significant form of debris in nuclear power reactor containments is piping and component insulation that becomes debris during LOCAs, is transported and accumulates in the sumps, and clogs the sumps strainers, thus creating resistance to coolant flow. Fibrous debris from this insulation can also enter the reactor core and directly impede heat transfer from the fuel to the coolant. The licensee also requested exemptions from GDC 35, which contain ECCS performance requirements, and GDCs 38 and 41, which respectively set performance requirements for reactor containment heat removal following a LOCA and for containment atmosphere cleanup following postulated accidents. The approval of a risk-informed methodology would require exemptions from 10 CFR 50.46(a)(1)(i) and GDCs 35, 38, and 41 because the NRC has interpreted these regulations as requiring a deterministic approach and bounding calculation to show compliance with ECCS and CSS performance criteria in 10 CFR 50.46(b) and GDCs 35, 38 and 41. Issuance of exemptions is an appropriate means to grant relief from the use of a deterministic approach to show compliance with these requirements. The licensee’s 10 CFR 50.46 deterministic analysis considered the debris in containment and demonstrated that the debris loading could prevent acceptable ECCS and CSS operation and core cooling for certain pipe ruptures. Based on its analysis, the licensee concluded that the amount of debris in the STP containment would need to be reduced to demonstrate compliance with 10 CFR 50.46 criteria using a deterministic analysis for certain largebreak LOCA sizes because, for those breaks, the plant-specific testing threshold for generation and transport of debris was exceeded. Additionally, the licensee’s deterministic thermal-hydraulic (TH) analysis could not show that hot-leg LOCAs greater than 16 inches could maintain adequate cooling. While not all large-break hot-leg LOCAs resulted in a loss of in-core cooling due to strainer blockage, the licensee categorized all hot-leg breaks greater than 16 inches as assumed to fail in order to simplify the TH analysis. The licensee requested exemptions from the requirement to use a deterministic analysis for specific scenarios of LOCA breaks producing and transporting debris in excess of the plant-specific tested debris limits and E:\FR\FM\19JYN1.SGM 19JYN1 asabaliauskas on DSKBBXCHB2PROD with NOTICES Federal Register / Vol. 82, No. 137 / Wednesday, July 19, 2017 / Notices for large hot-leg breaks. Since it determined that the probability of consequences from debris effects is very low, the licensee requested an exemption to use a risk-informed analysis to show adequate assurance of ECCS and CSS functionality, in accordance with the criteria in Regulatory Guide (RG) 1.174, ‘‘An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis.’’ The RG 1.174 was developed in consideration of the Commission’s Policy Statements on safety goals and the use of probabilistic risk assessment methods in nuclear regulatory activities (‘‘Safety Goals for the Operations of Nuclear Power Plants; Policy Statement,’’ August 4, 1986, 51 FR 30028; and ‘‘Use of Probabilistic Risk Assessment Methods in Nuclear Activities; Final Policy Statement,’’ August 16, 1995, 60 FR 42622, respectively). Therefore, RG 1.174 provides an acceptable method for licensees and NRC staff to use in assessing the impact of licensing basis changes when the licensee chooses to use risk information. The GDC 35, in part, requires that the ECCS safety system functions adequately to transfer heat from the reactor core following a LOCA and in the presence of a worst single failure, at a rate such that (a) fuel and clad damage that could interfere with continued effective core cooling is prevented and (b) clad metal-water reactor is limited to negligible amounts. The licensee stated in its submittal that the function of the ECCS emergency sump is assumed to fail for debris that exceeds the amount determined in acceptable plant-specific testing. Failure of the sump and strainers result in loss of cooling to the core. The licensee requested an exemption from the deterministic requirements of GDC 35 to use a riskinformed approach to show ECCS function for those LOCA breaks that exceed the plant-specific testing debris threshold, and for large hot-leg breaks. The use of a risk-informed analysis, in accordance with the criteria in RG 1.174, would allow the licensee to show that the risk from debris effects is very low. The GDC 38 requires containment heat removal, rapid reduction of containment pressure and temperature, and maintenance of pressure and temperature at an acceptably low level following a LOCA, and in the presence of a single failure, to preserve containment function. The STPNOC proposed that an exemption be granted from the deterministic requirements in GDC 38, for those LOCA breaks that VerDate Sep<11>2014 18:49 Jul 18, 2017 Jkt 241001 exceed the plant-specific testing debris threshold. Current STP design basis calculations are based on the reactor containment fan coolers functioning in conjunction with the CSS and ECCS, both of which can be affected by debris. Using deterministic assumptions, STPNOC’s analysis and testing does not assure that the emergency sump strainers will be available to support the CSS and ECCS function considering the effects of debris produced by those breaks that can generate and transport debris amounts greater than the plantspecific testing threshold. The licensee requested an exemption from the deterministic requirements of GDC 38 to use a risk-informed analysis, in accordance with the criteria in RG 1.174, to show that the risk from debris effects is very low. The GDC 41, in part, requires containment atmosphere cleanup to control substances that may be released into the reactor containment, to reduce the concentration and quality of fission products released to the environment following postulated accidents, and to control the concentration of hydrogen or oxygen and other substances in the containment atmosphere following postulated accidents, assuming a single failure. The licensee stated that using deterministic assumptions, STPNOC’s analysis and testing cannot demonstrate that the emergency sump strainers will be available to support the CSS function considering the effects of debris produced and transported by breaks not bounded by acceptable plant-specific testing. The licensee requested an exemption from the deterministic requirements of GDC 41 to use a riskinformed analysis, in accordance with the criteria in RG 1.174, to show that the risk from debris effects is very low. III. Discussion Pursuant to 10 CFR 50.12, the Commission may, upon application by any interested person or upon its own initiative, grant exemptions from the requirements of 10 CFR part 50, when (1) the exemptions are authorized by law, will not present an undue risk to public health or safety, and are consistent with the common defense and security; and (2) when special circumstances are present. Under 10 CFR 50.12(a)(2)(ii), special circumstances are present ‘‘when application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule.’’ The licensee proposed to use a riskinformed methodology instead of a deterministic approach to account for PO 00000 Frm 00124 Fmt 4703 Sfmt 4703 33163 the effects of debris in containment for portions of the LOCA analysis applicable to breaks that exceed the STP plant-specific debris testing threshold and large hot-leg piping breaks. The STPNOC methodology, termed Risk over Deterministic, or RoverD, divides the loss of core cooling design-basis analysis into two portions: the ‘‘deterministic analysis’’ and the ‘‘riskinformed analysis.’’ The risk-informed analysis is used by the licensee for breaks that generate and transport debris exceeding the plant-specific testing threshold. These breaks result in low density fiber glass fiber fines estimated to arrive in the ECCS sump post-LOCA in amounts that are equal to or greater than the amount of fines used in acceptable strainer testing. The acceptable limit was determined using testing methods intended to determine the maximum ECCS strainer head loss for the tested condition. Also, the licensee evaluated the incore TH aspects of fibrous debris to prevent adequate fuel cooling, finding that hot-leg breaks greater than 16 inches have the potential to prevent adequate in-core cooling. In order to simplify its TH evaluation, the licensee assumed that all large breaks greater than 16 inches in the hot-leg will result in the loss of the cooling function. For ECCS and CSS analyses other than the postulated large-break LOCAs in the hot-leg piping in containment and those breaks that exceed the STP plantspecific testing limit, STPNOC applied a deterministic methodology. If the exemptions were granted for these postulated breaks, the requirement to use a deterministic methodology for all other postulated LOCA breaks would continue to apply. A. Special Circumstances Under the regulations in 10 CFR 50.12, the Commission may grant exemptions from the requirements of 10 CFR part 50 provided certain findings are made; namely, that special circumstances are present, the exemptions present no undue risk to public health and safety, the exemptions are consistent with the common defense and security, and the exemptions are authorized by law. The exemptions would allow the licensee to use a riskinformed methodology to show compliance with 10 CFR 50.46(b), and GDCs 35, 38, and 41, specifically for the analyses of debris in containment impacting emergency cooling function during postulated large-break hot-leg LOCAs and those breaks that exceed the plant-specific testing threshold. The licensee requested exemptions citing the special circumstances criteria E:\FR\FM\19JYN1.SGM 19JYN1 asabaliauskas on DSKBBXCHB2PROD with NOTICES 33164 Federal Register / Vol. 82, No. 137 / Wednesday, July 19, 2017 / Notices of 10 CFR 50.12(a)(2)(ii), because compliance in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule. The licensee stated that these special circumstances are common to all of the requested exemptions. The licensee stated that an objective of each of the regulations for which an exemption is proposed is to maintain low risk to the public health and safety through the adequate functioning of the ECCS and CSS safety systems. These systems must be supported by adequate functioning of the containment sumps. The regulations in 10 CFR 50.46(a)(1)(i) and GDCs 35, 38, and 41 are met when the licensee is able to demonstrate, using a bounding calculation or other deterministic method that the ECCS and CSS are capable of functioning during design basis events. The STPNOC stated that its risk-informed analysis to show adequate functioning of ECCS and CSS considering the impacts of debris during certain LOCA events demonstrates that the risk of failure of these systems is very small. The licensee stated that special circumstances exist because the underlying intent of the regulations, to ensure adequate protection of public health and safety is met when applying a risk-informed approach to address GSI–191 and respond to GL 2004–02. Further, it states that the risk-informed approach is consistent with RG 1.174, and supports operation of those functions with a high degree of reliability. Thus, the licensee concludes that the underlying intent of each regulation is met and the special circumstances described in 10 CFR 50.12(a)(2)(ii) apply to each of the exemptions proposed by STPNOC. The NRC staff evaluated the STPNOC submittal and supplements, and discussed the details of its evaluation of the risk-informed approach in an NRC safety evaluation available in ADAMS under Accession No. ML17019A001. Although 10 CFR 50.46(a)(1) requires a deterministic approach, the GDCs do not specify that a risk-informed methodology may not be used to show compliance; however, because the NRC has interpreted each of these regulations as requiring a deterministic approach, an exemption is an appropriate means to grant the licensee relief to use an alternative approach. The underlying purpose of each regulation is to protect public health and safety in the event of a LOCA by establishing criteria for emergency core cooling, containment cooling and containment atmosphere cleanup system performance. In its safety evaluation, the NRC staff VerDate Sep<11>2014 18:49 Jul 18, 2017 Jkt 241001 concluded, in part, that the licensee adequately demonstrated that the change in risk attributable to debris in postulated hot-leg LOCAs greater than 16 inches, and those breaks that exceed the plant specific threshold, is very small. The NRC staff also concluded that the licensee’s proposal for demonstrating compliance with the ECCS and CSS performance requirements meet the risk acceptance guidelines in RG 1.174 because the approach is related to a permissible exemption request, is consistent with defense-in-depth philosophy, maintains sufficient safety margins, results in a small increase in risk, and the impact of this approach is monitored by the licensee using performance measurement strategies. Therefore, the licensee’s use of the risk-informed analysis to consider the impacts of debris meets the underlying requirements of 10 CFR 50.46 and GDCs 35, 38, and 41, to ensure that a licensee demonstrates that the ECCS and CSS will provide adequate cooling for the reactor core and containment, as well as containment atmosphere cleanup following postulated design-basis accidents. Based on the above, the NRC staff concludes that special circumstances under 10 CFR 50.12(a)(2)(ii) exist because compliance with the deterministic requirements of 10 CFR 50.46(a)(1)(i), and GDCs 35, 38, and 41 is not necessary to achieve the underlying purpose of each rule. B. The Exemption Presents No Undue Risk to Public Health and Safety The provisions of 10 CFR 50.46 and GDCs 35, 38, and 41 establish criteria for the emergency core cooling, containment cooling, and containment atmosphere cleanup system performance. As part of the amendment requests, the STPNOC submitted exemption requests to change its designbasis analysis specified in the Updated Final Safety Analysis Report (UFSAR) to use new risk-informed and deterministic methodologies to specifically account for the impacts of debris in containment. The licensee justified its use of the risk-informed approach by stating that the proposed risk-informed approach meets the key principles in RG 1.174 in that it is consistent with defense-in-depth philosophy, maintains sufficient safety margins, results in a small increase in risk, and is monitored by the licensee using performance measurement strategies. Additionally, the licensee stated that the proposed exemptions to use the riskinformed method are consistent with PO 00000 Frm 00125 Fmt 4703 Sfmt 4703 Key Principle 1 in RG 1.174 that requires a proposed change to the licensing basis (or amendment) to meet current regulations unless the change is explicitly related to a requested exemption. The licensee’s probabilistic risk analysis results provided by the licensee and evaluated by the NRC staff in its safety evaluation, showed that the increase in risk associated with debris generation and transport on ECCS and CSS function following postulated LOCAs is very low, in accordance with the criteria in RG 1.174. The NRC staff concluded that the risk is consistent with the guidance in RG 1.174 and with the Commission policy statements on safety goals and the use of probabilistic risk assessment methods in nuclear regulatory activities; therefore, the requested exemption presents no undue risk to public health and safety. C. The Exemption Is Consistent With the Common Defense and Security The requested exemptions to use a risk-informed methodology allow STPNOC to resolve a generic safety concern for PWRs associated with potential clogging of the ECCS and CSS strainers during certain design-basis events. The change is adequately controlled by safety acceptance criteria and technical specification requirements and is not related to security issues. Because the common defense and security is not impacted by the exemption, the exemption is consistent with the common defense and security. D. The Exemptions Are Authorized by Law The exemptions to use a riskinformed methodology allow STPNOC to show compliance with 10 CFR 50.46(a)(1)(i), and GDCs 35, 38, and 41, when considering debris in containment generated and transported during postulated hot-leg LOCA breaks greater than 16 inches, and those breaks that exceed the plant-specific testing threshold. These regulations were promulgated under, and are consistent with the Commission’s authority under Section 161 of the Atomic Energy Act. Because the application of a riskinformed methodology to show compliance with 10 CFR 50.46, and GDC 35, 38, and 41 would not violate the Atomic Energy Act of 1954, as amended, or the Commission’s regulations, the exemptions are authorized by law provided all requisite findings are made. E:\FR\FM\19JYN1.SGM 19JYN1 33165 Federal Register / Vol. 82, No. 137 / Wednesday, July 19, 2017 / Notices E. Environmental Considerations Pursuant to 10 CFR 51.21, ‘‘Criteria for and identification of licensing and regulatory actions requiring environmental assessments,’’ the NRC has prepared an Environmental Assessment (EA) summarizing the findings of its review of the environmental impacts of the proposed action under the National Environmental Policy Act. The NRC staff determined that special circumstances under 10 CFR 51.21 exist to warrant preparation of an EA because STP is the pilot plant to propose a riskinformed approach to resolve GSI–191 as recognized in Staff Requirement Memorandum SECY–12–0093, ‘‘Closure Options for Generic Safety Issue–191, Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance,’’ dated December 14, 2012. Because this is the first approval of a risk-informed approach, the NRC staff considered preparations of an EA to be a prudent course of action that would further the purposes of the National Environmental Policy Act. Based on its review, the NRC concluded that an environmental impact statement is not required and that the proposed action will have no significant impact on the environment. The NRC published a final EA on the proposed action in the Federal Register on May 9, 2017 (82 FR 21568). consistent with the common defense and security, and special circumstances are present pursuant to 10 CFR 50.12(a)(2)(ii). Therefore, the NRC hereby grants STPNOC a one-time exemption from 10 CFR 50.46(a)(1), and 10 CFR part 50, appendix A, GDCs 35, 38, and 41 to use a risk-informed methodology in lieu of a deterministic methodology to show conformance with the ECCS and CSS performance criteria accounting for debris in containment for large-break hot-leg LOCAs and those breaks that exceed the plant-specific STP testing threshold. IV. Conclusions V. Availability of Documents Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12, exemptions are authorized by law, will not present an undue risk to the public health and safety, are The documents identified in the following table are available for public inspection through the NRC’s Agencywide Documents Access and Management System (ADAMS). Date Title ADAMS accession No. NRC Generic Letter 2004–02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors ................................................................................................................................................................. STPNOC letter to NRC, Revised STP Pilot Submittal and Requests for Exemptions and License Amendment for a Risk-Informed Approach to Resolving Generic Safety Issue (GSI)-191 ...................................................................................................................... 9/13/2004 ML042360586 6/19/2013 ML131750250 (Package) STPNOC letter to NRC, Supplement 2 to STP Pilot Submittal and Requests for Exemptions and License Amendment for a Risk-Informed Approach to Address Generic Safety Issue (GSI)-191 and Respond to Generic Letter (GL) 2004–02 .................................. 8/20/15 ML15246A125 (Package) 4/13/2016 ML16111B204 5/2011 ML100910006 7/11/2017 ML17019A001 (Package) 12/14/2012 ML12349A378 5/02/2017 ML16278A598 STPNOC letter to NRC, South Texas Project, Units 1 and 2—Revision to Proposed Exemption to 10 CFR 50.46 Described in Pilot Submittal and Requests for Exemptions and License Amendment for a Risk-Informed Approach to Address Generic Safety Issue (GSI)-191 and Respond to Generic Letter (GL) 2004–02 .................................................................................................................... Regulatory Guide 1.174, Revision 2, ‘‘An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on PlantSpecific Changes to the Licensing Basis’’ ............................................................................................................................................ NRC letter to STPNOC, South Texas Project, Units 1 and 2—Issuance of Amendment Nos. 212 and 198—Risk-Informed Approach to Resolve Generic Safety Issue-191 (includes Safety Evaluation) ..................................................................................................... Commission SRM–SECY–12–0093, Staff Requirements—SECY–12–0093—Closure Options for Generic Safety Issue—191, Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance ...................................................................... NRC Letter to STPNOC, South Texas Project, Units 1 and 2—Letter, Environmental Assessment and Finding of No Significant Impact, Revise Licensing Basis as Documented in the UFSAR and Request for Exemptions, Risk-Informed approach to Address GSI-191 ................................................................................................................................................................................................. Dated at Rockville, Maryland, this 11th day of July 2017. For the Nuclear Regulatory Commission. Eric J. Benner, Deputy Director, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation. [FR Doc. 2017–15136 Filed 7–18–17; 8:45 am] BILLING CODE 7590–01–P asabaliauskas on DSKBBXCHB2PROD with NOTICES PENSION BENEFIT GUARANTY CORPORATION Proposed Submission of Information Collection for OMB Review; Comment Request; Annual Reporting (Form 5500 Series) Pension Benefit Guaranty Corporation. ACTION: Notice of request for extension of OMB approval without change. AGENCY: VerDate Sep<11>2014 18:49 Jul 18, 2017 Jkt 241001 The Pension Benefit Guaranty Corporation (PBGC) is requesting that the Office of Management and Budget (OMB) extend approval without change, under the Paperwork Reduction Act of 1995, of its collection of information for Annual Reporting (OMB control number 1212–0057, expires July 31, 2017). This notice informs the public of PBGC’s request and solicits public comment on the collection of information. DATES: Comments must be submitted by August 18, 2017. ADDRESSES: Comments should be sent to the Office of Informatioon and Regulatory Affairs, Office of Management and Budget, Attention: Desk Officer for Pension Benefit Guaranty Corporation, via electronic mail at OIRA_DOCKET@omb.eop.gov or by fax to (202) 395–6974. A copy of the request will be posted at https:// www.pbgc.gov/prac/pg/other/guidance/ paperwork-notices. It may also be SUMMARY: PO 00000 Frm 00126 Fmt 4703 Sfmt 4703 obtained without charge by writing to the Disclosure Division of the Office of the General Counsel, Pension Benefit Guaranty Corporation, 1200 K Street NW., Washington, DC 20005, or calling 202–326–4040 during normal business hours. TTY and TDD users may call the Federal relay service toll-free at 1 800– 877–8339 and ask to be connected to 202–326–4040. Jo Amato Burns (burns.jo.amato@ pbgc.gov), Regulatory Affairs Group, Office of the General Counsel, Pension Benefit Guaranty Corporation, 1200 K Street NW., Washington, DC 20005, 202–326–4400, extension 3072, or Deborah Chase Murphy (murphy.deborah@pbgc.gov), Assistant General Counsel, same address and phone number, extension 3451. TTY and TDD users may call the Federal relay service toll-free at 800–877–8339 FOR FURTHER INFORMATION CONTACT: E:\FR\FM\19JYN1.SGM 19JYN1

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[Federal Register Volume 82, Number 137 (Wednesday, July 19, 2017)]
[Notices]
[Pages 33161-33165]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-15136]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. 50-498 and 50-499; NRC-2016-0092]


STP Nuclear Operating Company; South Texas Project, Units 1 and 2

AGENCY: Nuclear Regulatory Commission.

ACTION: Exemption; issuance.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is granting 
exemptions from certain portions of the acceptance criteria for 
emergency core cooling, and the general design criteria for emergency 
core cooling, containment heat removal, and atmosphere cleanup for the 
use of a risk-informed analysis to evaluate the effects of debris in 
containment following a loss-of-coolant accident (LOCA) for the South 
Texas Project (STP), Units 1 and 2, located in Matagorda County, Texas, 
Docket Nos. 50-498 and 50-499, respectively. The exemptions are in 
response to a request dated June 19,

[[Page 33162]]

2013, from the STP Nuclear Operating Company (STPNOC, the licensee) 
related to STPNOC's proposed approach to resolve a generic safety 
concern for pressurized water reactors (PWRs) associated with potential 
clogging of emergency core cooling and containment spray system 
strainers during certain design basis events.

DATES: The exemption was issued on July 11, 2017.

ADDRESSES: Please refer to Docket ID NRC-2016-0092 when contacting the 
NRC about the availability of information regarding this document. You 
may obtain publicly-available information related to this document 
using any of the following methods:
     Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2016-0092. Address 
questions about NRC dockets to Carol Gallagher; telephone: 301-415-
3463; email: Carol.Gallagher@nrc.gov. For technical questions, contact 
the individual listed in the FOR FURTHER INFORMATION CONTACT section of 
this document.
     NRC's Agencywide Documents Access and Management System 
(ADAMS): You may obtain publicly-available documents online in the 
ADAMS Public Documents collection at http://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``ADAMS Public Documents'' and 
then 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, 301-415-4737, or by email to pdr.resource@nrc.gov. For 
the convenience of the reader, the ADAMS accession numbers are provided 
in a table in the ``Availability of Documents'' section of this 
document.
     NRC's PDR: You may examine and purchase copies of public 
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, Maryland 20852.

FOR FURTHER INFORMATION CONTACT: Lisa Regner, Office of Nuclear Reactor 
Regulation, U.S. Nuclear Regulatory Commission, Washington DC 20555-
0001; telephone: 301-415-1906, email: Lisa.Regner@nrc.gov.

SUPPLEMENTARY INFORMATION:

I. Background

    The licensee is the holder of Facility Operating License Nos. NPF-
76 and NPF-80, which authorize operation of the STP Units 1 and 2, 
respectively. The licenses provide, among other things, that the 
facility is subject to all rules, regulations, and orders of the NRC 
now or hereafter in effect. The facility consists of two PWRs located 
in Matagorda County, Texas.
    In 1996, the NRC identified Generic Safety Issue (GSI)-191 
associated with the effects of debris accumulation on PWR sump 
performance during design-basis accidents. As part of the actions to 
resolve GSI-191, the NRC issued Generic Letter (GL) 2004-02, 
``Potential Impact of Debris Blockage on Emergency Recirculation during 
Design Basis Accidents at Pressurized-Water Reactors,'' dated September 
13, 2004, to holders of operating licenses for PWRs. In GL 2004-02, the 
NRC staff requested that licensees perform an evaluation of their 
emergency core cooling systems (ECCS) and containment spray system 
(CSS) recirculation functions considering the potential for debris-
laden coolant to be circulated by the ECCS and the CSS after a LOCA or 
high energy line break inside containment and, if appropriate, take 
additional actions to ensure system function. The GL required that 
licensees provide a written response to the NRC, pursuant to section 
50.54(f) of title 10 of the Code of Federal Regulations (10 CFR), 
describing the results of their evaluation and any modifications made, 
or planned, to ensure the ECCS and CSS remain functional.

II. Request/Action

    By letter dated June 19, 2013, as supplemented by letters dated 
August 20, 2015, and April 13, 2016, STPNOC submitted requests for 
exemptions pursuant to 10 CFR 50.12, ``Specific exemptions,'' from the 
requirements of 10 CFR 50.46, ``Acceptance criteria for emergency core 
cooling systems for light-water nuclear power reactors,'' and 10 CFR 
part 50, appendix A, General Design Criterion (GDC) 35, ``Emergency 
core cooling,'' GDC 38, ``Containment heat removal,'' and GDC 41, 
``Containment atmosphere cleanup,'' to use a risk-informed methodology 
instead of the traditional deterministic methodology, to resolve the 
concerns associated with GSI-191 and respond to GL 2004-02.
    Specifically, the licensee requested an exemption from 10 CFR 
50.46(a)(1)(i), which, in part, requires ECCS cooling performance to be 
calculated in accordance with an acceptable evaluation model, as 
described in 10 CFR 50.46(a)(1), for postulated LOCAs of different 
sizes, locations and other properties sufficient to provide assurance 
that the most severe LOCAs are evaluated in order to demonstrate that 
acceptance criteria in 10 CFR 50.46(b) are met. The NRC staff 
interprets 10 CFR 50.46(a)(1) requirement to calculate ECCS performance 
for ``other properties'' as requiring licensees to consider the impacts 
of debris generation and transport in containment. The most significant 
form of debris in nuclear power reactor containments is piping and 
component insulation that becomes debris during LOCAs, is transported 
and accumulates in the sumps, and clogs the sumps strainers, thus 
creating resistance to coolant flow. Fibrous debris from this 
insulation can also enter the reactor core and directly impede heat 
transfer from the fuel to the coolant. The licensee also requested 
exemptions from GDC 35, which contain ECCS performance requirements, 
and GDCs 38 and 41, which respectively set performance requirements for 
reactor containment heat removal following a LOCA and for containment 
atmosphere cleanup following postulated accidents.
    The approval of a risk-informed methodology would require 
exemptions from 10 CFR 50.46(a)(1)(i) and GDCs 35, 38, and 41 because 
the NRC has interpreted these regulations as requiring a deterministic 
approach and bounding calculation to show compliance with ECCS and CSS 
performance criteria in 10 CFR 50.46(b) and GDCs 35, 38 and 41. 
Issuance of exemptions is an appropriate means to grant relief from the 
use of a deterministic approach to show compliance with these 
requirements.
    The licensee's 10 CFR 50.46 deterministic analysis considered the 
debris in containment and demonstrated that the debris loading could 
prevent acceptable ECCS and CSS operation and core cooling for certain 
pipe ruptures. Based on its analysis, the licensee concluded that the 
amount of debris in the STP containment would need to be reduced to 
demonstrate compliance with 10 CFR 50.46 criteria using a deterministic 
analysis for certain large-break LOCA sizes because, for those breaks, 
the plant-specific testing threshold for generation and transport of 
debris was exceeded.
    Additionally, the licensee's deterministic thermal-hydraulic (TH) 
analysis could not show that hot-leg LOCAs greater than 16 inches could 
maintain adequate cooling. While not all large-break hot-leg LOCAs 
resulted in a loss of in-core cooling due to strainer blockage, the 
licensee categorized all hot-leg breaks greater than 16 inches as 
assumed to fail in order to simplify the TH analysis.
    The licensee requested exemptions from the requirement to use a 
deterministic analysis for specific scenarios of LOCA breaks producing 
and transporting debris in excess of the plant-specific tested debris 
limits and

[[Page 33163]]

for large hot-leg breaks. Since it determined that the probability of 
consequences from debris effects is very low, the licensee requested an 
exemption to use a risk-informed analysis to show adequate assurance of 
ECCS and CSS functionality, in accordance with the criteria in 
Regulatory Guide (RG) 1.174, ``An Approach for Using Probabilistic Risk 
Assessment in Risk-Informed Decisions on Plant-Specific Changes to the 
Licensing Basis.'' The RG 1.174 was developed in consideration of the 
Commission's Policy Statements on safety goals and the use of 
probabilistic risk assessment methods in nuclear regulatory activities 
(``Safety Goals for the Operations of Nuclear Power Plants; Policy 
Statement,'' August 4, 1986, 51 FR 30028; and ``Use of Probabilistic 
Risk Assessment Methods in Nuclear Activities; Final Policy 
Statement,'' August 16, 1995, 60 FR 42622, respectively). Therefore, RG 
1.174 provides an acceptable method for licensees and NRC staff to use 
in assessing the impact of licensing basis changes when the licensee 
chooses to use risk information.
    The GDC 35, in part, requires that the ECCS safety system functions 
adequately to transfer heat from the reactor core following a LOCA and 
in the presence of a worst single failure, at a rate such that (a) fuel 
and clad damage that could interfere with continued effective core 
cooling is prevented and (b) clad metal-water reactor is limited to 
negligible amounts. The licensee stated in its submittal that the 
function of the ECCS emergency sump is assumed to fail for debris that 
exceeds the amount determined in acceptable plant-specific testing. 
Failure of the sump and strainers result in loss of cooling to the 
core. The licensee requested an exemption from the deterministic 
requirements of GDC 35 to use a risk-informed approach to show ECCS 
function for those LOCA breaks that exceed the plant-specific testing 
debris threshold, and for large hot-leg breaks. The use of a risk-
informed analysis, in accordance with the criteria in RG 1.174, would 
allow the licensee to show that the risk from debris effects is very 
low.
    The GDC 38 requires containment heat removal, rapid reduction of 
containment pressure and temperature, and maintenance of pressure and 
temperature at an acceptably low level following a LOCA, and in the 
presence of a single failure, to preserve containment function. The 
STPNOC proposed that an exemption be granted from the deterministic 
requirements in GDC 38, for those LOCA breaks that exceed the plant-
specific testing debris threshold. Current STP design basis 
calculations are based on the reactor containment fan coolers 
functioning in conjunction with the CSS and ECCS, both of which can be 
affected by debris. Using deterministic assumptions, STPNOC's analysis 
and testing does not assure that the emergency sump strainers will be 
available to support the CSS and ECCS function considering the effects 
of debris produced by those breaks that can generate and transport 
debris amounts greater than the plant-specific testing threshold. The 
licensee requested an exemption from the deterministic requirements of 
GDC 38 to use a risk-informed analysis, in accordance with the criteria 
in RG 1.174, to show that the risk from debris effects is very low.
    The GDC 41, in part, requires containment atmosphere cleanup to 
control substances that may be released into the reactor containment, 
to reduce the concentration and quality of fission products released to 
the environment following postulated accidents, and to control the 
concentration of hydrogen or oxygen and other substances in the 
containment atmosphere following postulated accidents, assuming a 
single failure. The licensee stated that using deterministic 
assumptions, STPNOC's analysis and testing cannot demonstrate that the 
emergency sump strainers will be available to support the CSS function 
considering the effects of debris produced and transported by breaks 
not bounded by acceptable plant-specific testing. The licensee 
requested an exemption from the deterministic requirements of GDC 41 to 
use a risk-informed analysis, in accordance with the criteria in RG 
1.174, to show that the risk from debris effects is very low.

III. Discussion

    Pursuant to 10 CFR 50.12, the Commission may, upon application by 
any interested person or upon its own initiative, grant exemptions from 
the requirements of 10 CFR part 50, when (1) the exemptions are 
authorized by law, will not present an undue risk to public health or 
safety, and are consistent with the common defense and security; and 
(2) when special circumstances are present. Under 10 CFR 
50.12(a)(2)(ii), special circumstances are present ``when application 
of the regulation in the particular circumstances would not serve the 
underlying purpose of the rule or is not necessary to achieve the 
underlying purpose of the rule.''
    The licensee proposed to use a risk-informed methodology instead of 
a deterministic approach to account for the effects of debris in 
containment for portions of the LOCA analysis applicable to breaks that 
exceed the STP plant-specific debris testing threshold and large hot-
leg piping breaks. The STPNOC methodology, termed Risk over 
Deterministic, or RoverD, divides the loss of core cooling design-basis 
analysis into two portions: the ``deterministic analysis'' and the 
``risk-informed analysis.'' The risk-informed analysis is used by the 
licensee for breaks that generate and transport debris exceeding the 
plant-specific testing threshold. These breaks result in low density 
fiber glass fiber fines estimated to arrive in the ECCS sump post-LOCA 
in amounts that are equal to or greater than the amount of fines used 
in acceptable strainer testing. The acceptable limit was determined 
using testing methods intended to determine the maximum ECCS strainer 
head loss for the tested condition.
    Also, the licensee evaluated the in-core TH aspects of fibrous 
debris to prevent adequate fuel cooling, finding that hot-leg breaks 
greater than 16 inches have the potential to prevent adequate in-core 
cooling. In order to simplify its TH evaluation, the licensee assumed 
that all large breaks greater than 16 inches in the hot-leg will result 
in the loss of the cooling function. For ECCS and CSS analyses other 
than the postulated large-break LOCAs in the hot-leg piping in 
containment and those breaks that exceed the STP plant-specific testing 
limit, STPNOC applied a deterministic methodology. If the exemptions 
were granted for these postulated breaks, the requirement to use a 
deterministic methodology for all other postulated LOCA breaks would 
continue to apply.

A. Special Circumstances

    Under the regulations in 10 CFR 50.12, the Commission may grant 
exemptions from the requirements of 10 CFR part 50 provided certain 
findings are made; namely, that special circumstances are present, the 
exemptions present no undue risk to public health and safety, the 
exemptions are consistent with the common defense and security, and the 
exemptions are authorized by law. The exemptions would allow the 
licensee to use a risk-informed methodology to show compliance with 10 
CFR 50.46(b), and GDCs 35, 38, and 41, specifically for the analyses of 
debris in containment impacting emergency cooling function during 
postulated large-break hot-leg LOCAs and those breaks that exceed the 
plant-specific testing threshold.
    The licensee requested exemptions citing the special circumstances 
criteria

[[Page 33164]]

of 10 CFR 50.12(a)(2)(ii), because compliance in the particular 
circumstances would not serve the underlying purpose of the rule or is 
not necessary to achieve the underlying purpose of the rule. The 
licensee stated that these special circumstances are common to all of 
the requested exemptions.
    The licensee stated that an objective of each of the regulations 
for which an exemption is proposed is to maintain low risk to the 
public health and safety through the adequate functioning of the ECCS 
and CSS safety systems. These systems must be supported by adequate 
functioning of the containment sumps. The regulations in 10 CFR 
50.46(a)(1)(i) and GDCs 35, 38, and 41 are met when the licensee is 
able to demonstrate, using a bounding calculation or other 
deterministic method that the ECCS and CSS are capable of functioning 
during design basis events. The STPNOC stated that its risk-informed 
analysis to show adequate functioning of ECCS and CSS considering the 
impacts of debris during certain LOCA events demonstrates that the risk 
of failure of these systems is very small. The licensee stated that 
special circumstances exist because the underlying intent of the 
regulations, to ensure adequate protection of public health and safety 
is met when applying a risk-informed approach to address GSI-191 and 
respond to GL 2004-02. Further, it states that the risk-informed 
approach is consistent with RG 1.174, and supports operation of those 
functions with a high degree of reliability. Thus, the licensee 
concludes that the underlying intent of each regulation is met and the 
special circumstances described in 10 CFR 50.12(a)(2)(ii) apply to each 
of the exemptions proposed by STPNOC.
    The NRC staff evaluated the STPNOC submittal and supplements, and 
discussed the details of its evaluation of the risk-informed approach 
in an NRC safety evaluation available in ADAMS under Accession No. 
ML17019A001. Although 10 CFR 50.46(a)(1) requires a deterministic 
approach, the GDCs do not specify that a risk-informed methodology may 
not be used to show compliance; however, because the NRC has 
interpreted each of these regulations as requiring a deterministic 
approach, an exemption is an appropriate means to grant the licensee 
relief to use an alternative approach. The underlying purpose of each 
regulation is to protect public health and safety in the event of a 
LOCA by establishing criteria for emergency core cooling, containment 
cooling and containment atmosphere cleanup system performance. In its 
safety evaluation, the NRC staff concluded, in part, that the licensee 
adequately demonstrated that the change in risk attributable to debris 
in postulated hot-leg LOCAs greater than 16 inches, and those breaks 
that exceed the plant specific threshold, is very small. The NRC staff 
also concluded that the licensee's proposal for demonstrating 
compliance with the ECCS and CSS performance requirements meet the risk 
acceptance guidelines in RG 1.174 because the approach is related to a 
permissible exemption request, is consistent with defense-in-depth 
philosophy, maintains sufficient safety margins, results in a small 
increase in risk, and the impact of this approach is monitored by the 
licensee using performance measurement strategies. Therefore, the 
licensee's use of the risk-informed analysis to consider the impacts of 
debris meets the underlying requirements of 10 CFR 50.46 and GDCs 35, 
38, and 41, to ensure that a licensee demonstrates that the ECCS and 
CSS will provide adequate cooling for the reactor core and containment, 
as well as containment atmosphere cleanup following postulated design-
basis accidents.
    Based on the above, the NRC staff concludes that special 
circumstances under 10 CFR 50.12(a)(2)(ii) exist because compliance 
with the deterministic requirements of 10 CFR 50.46(a)(1)(i), and GDCs 
35, 38, and 41 is not necessary to achieve the underlying purpose of 
each rule.

B. The Exemption Presents No Undue Risk to Public Health and Safety

    The provisions of 10 CFR 50.46 and GDCs 35, 38, and 41 establish 
criteria for the emergency core cooling, containment cooling, and 
containment atmosphere cleanup system performance. As part of the 
amendment requests, the STPNOC submitted exemption requests to change 
its design-basis analysis specified in the Updated Final Safety 
Analysis Report (UFSAR) to use new risk-informed and deterministic 
methodologies to specifically account for the impacts of debris in 
containment. The licensee justified its use of the risk-informed 
approach by stating that the proposed risk-informed approach meets the 
key principles in RG 1.174 in that it is consistent with defense-in-
depth philosophy, maintains sufficient safety margins, results in a 
small increase in risk, and is monitored by the licensee using 
performance measurement strategies.
    Additionally, the licensee stated that the proposed exemptions to 
use the risk-informed method are consistent with Key Principle 1 in RG 
1.174 that requires a proposed change to the licensing basis (or 
amendment) to meet current regulations unless the change is explicitly 
related to a requested exemption. The licensee's probabilistic risk 
analysis results provided by the licensee and evaluated by the NRC 
staff in its safety evaluation, showed that the increase in risk 
associated with debris generation and transport on ECCS and CSS 
function following postulated LOCAs is very low, in accordance with the 
criteria in RG 1.174.
    The NRC staff concluded that the risk is consistent with the 
guidance in RG 1.174 and with the Commission policy statements on 
safety goals and the use of probabilistic risk assessment methods in 
nuclear regulatory activities; therefore, the requested exemption 
presents no undue risk to public health and safety.

C. The Exemption Is Consistent With the Common Defense and Security

    The requested exemptions to use a risk-informed methodology allow 
STPNOC to resolve a generic safety concern for PWRs associated with 
potential clogging of the ECCS and CSS strainers during certain design-
basis events. The change is adequately controlled by safety acceptance 
criteria and technical specification requirements and is not related to 
security issues. Because the common defense and security is not 
impacted by the exemption, the exemption is consistent with the common 
defense and security.

D. The Exemptions Are Authorized by Law

    The exemptions to use a risk-informed methodology allow STPNOC to 
show compliance with 10 CFR 50.46(a)(1)(i), and GDCs 35, 38, and 41, 
when considering debris in containment generated and transported during 
postulated hot-leg LOCA breaks greater than 16 inches, and those breaks 
that exceed the plant-specific testing threshold. These regulations 
were promulgated under, and are consistent with the Commission's 
authority under Section 161 of the Atomic Energy Act. Because the 
application of a risk-informed methodology to show compliance with 10 
CFR 50.46, and GDC 35, 38, and 41 would not violate the Atomic Energy 
Act of 1954, as amended, or the Commission's regulations, the 
exemptions are authorized by law provided all requisite findings are 
made.

[[Page 33165]]

E. Environmental Considerations

    Pursuant to 10 CFR 51.21, ``Criteria for and identification of 
licensing and regulatory actions requiring environmental assessments,'' 
the NRC has prepared an Environmental Assessment (EA) summarizing the 
findings of its review of the environmental impacts of the proposed 
action under the National Environmental Policy Act. The NRC staff 
determined that special circumstances under 10 CFR 51.21 exist to 
warrant preparation of an EA because STP is the pilot plant to propose 
a risk-informed approach to resolve GSI-191 as recognized in Staff 
Requirement Memorandum SECY-12-0093, ``Closure Options for Generic 
Safety Issue-191, Assessment of Debris Accumulation on Pressurized-
Water Reactor Sump Performance,'' dated December 14, 2012. Because this 
is the first approval of a risk-informed approach, the NRC staff 
considered preparations of an EA to be a prudent course of action that 
would further the purposes of the National Environmental Policy Act. 
Based on its review, the NRC concluded that an environmental impact 
statement is not required and that the proposed action will have no 
significant impact on the environment.
    The NRC published a final EA on the proposed action in the Federal 
Register on May 9, 2017 (82 FR 21568).

IV. Conclusions

    Accordingly, the Commission has determined that, pursuant to 10 CFR 
50.12, exemptions are authorized by law, will not present an undue risk 
to the public health and safety, are consistent with the common defense 
and security, and special circumstances are present pursuant to 10 CFR 
50.12(a)(2)(ii). Therefore, the NRC hereby grants STPNOC a one-time 
exemption from 10 CFR 50.46(a)(1), and 10 CFR part 50, appendix A, GDCs 
35, 38, and 41 to use a risk-informed methodology in lieu of a 
deterministic methodology to show conformance with the ECCS and CSS 
performance criteria accounting for debris in containment for large-
break hot-leg LOCAs and those breaks that exceed the plant-specific STP 
testing threshold.

V. Availability of Documents

    The documents identified in the following table are available for 
public inspection through the NRC's Agencywide Documents Access and 
Management System (ADAMS).

------------------------------------------------------------------------
                                                               ADAMS
                  Title                        Date        accession No.
------------------------------------------------------------------------
NRC Generic Letter 2004-02, Potential          9/13/2004     ML042360586
 Impact of Debris Blockage on Emergency
 Recirculation During Design Basis
 Accidents at Pressurized-Water Reactors
STPNOC letter to NRC, Revised STP Pilot        6/19/2013     ML131750250
 Submittal and Requests for Exemptions                         (Package)
 and License Amendment for a Risk-
 Informed Approach to Resolving Generic
 Safety Issue (GSI)-191.................
STPNOC letter to NRC, Supplement 2 to            8/20/15     ML15246A125
 STP Pilot Submittal and Requests for                          (Package)
 Exemptions and License Amendment for a
 Risk-Informed Approach to Address
 Generic Safety Issue (GSI)-191 and
 Respond to Generic Letter (GL) 2004-02.
STPNOC letter to NRC, South Texas              4/13/2016     ML16111B204
 Project, Units 1 and 2--Revision to
 Proposed Exemption to 10 CFR 50.46
 Described in Pilot Submittal and
 Requests for Exemptions and License
 Amendment for a Risk-Informed Approach
 to Address Generic Safety Issue (GSI)-
 191 and Respond to Generic Letter (GL)
 2004-02................................
Regulatory Guide 1.174, Revision 2, ``An          5/2011     ML100910006
 Approach for Using Probabilistic Risk
 Assessment in Risk-Informed Decisions
 on Plant-Specific Changes to the
 Licensing Basis''......................
NRC letter to STPNOC, South Texas              7/11/2017     ML17019A001
 Project, Units 1 and 2--Issuance of                           (Package)
 Amendment Nos. 212 and 198--Risk-
 Informed Approach to Resolve Generic
 Safety Issue-191 (includes Safety
 Evaluation)............................
Commission SRM-SECY-12-0093, Staff            12/14/2012     ML12349A378
 Requirements--SECY-12-0093--Closure
 Options for Generic Safety Issue--191,
 Assessment of Debris Accumulation on
 Pressurized-Water Reactor Sump
 Performance............................
NRC Letter to STPNOC, South Texas              5/02/2017     ML16278A598
 Project, Units 1 and 2--Letter,
 Environmental Assessment and Finding of
 No Significant Impact, Revise Licensing
 Basis as Documented in the UFSAR and
 Request for Exemptions, Risk-Informed
 approach to Address GSI[dash]191.......
------------------------------------------------------------------------


    Dated at Rockville, Maryland, this 11th day of July 2017.
    For the Nuclear Regulatory Commission.
Eric J. Benner,
Deputy Director, Division of Operating Reactor Licensing, Office of 
Nuclear Reactor Regulation.
[FR Doc. 2017-15136 Filed 7-18-17; 8:45 am]
 BILLING CODE 7590-01-P