ML25121A344
| ML25121A344 | |
| Person / Time | |
|---|---|
| Site: | Technical Specifications Task Force |
| Issue date: | 08/04/2025 |
| From: | Office of Nuclear Reactor Regulation |
| To: | Technical Specifications Task Force |
| References | |
| EPID L?2024?PMP?0007 | |
| Download: ML25121A344 (10) | |
Text
DRAFT SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 1
TECHNICAL SPECIFICATIONS TASK FORCE TRAVELER 2
TSTF-601, REVISION 1 3
EXTEND SHIELD BUILDING COMPLETION TIME AFTER REFUELING 4
USING THE CONSOLIDATED LINE-ITEM IMPROVEMENT PROCESS 5
(EPID: L2024PMP0007) 6 7
1.0 INTRODUCTION 8
9 By \
letter dated March 6, 2025 (Agencywide Documents Access and Management System 10 Accession No. ML25065A247), the Technical Specifications Task Force (TSTF) submitted 11 Traveler TSTF-601, Revision 1, Extend Shield Building Completion Time After Refueling, to 12 the U.S. Nuclear Regulatory Commission (NRC). Traveler TSTF-601 proposed to change the 13 shield building standard technical specifications (STS) for Westinghouse and Combustion 14 Engineering designed pressurized-water reactors (PWRs). Upon approval, this change would 15 be incorporated into future revisions of NUREG-1431 and NUREG-1432, and this traveler would 16 be available to licensees for adoption through the consolidated line-item improvement process 17 (CLIIP).1 18 19 The proposed change would revise the shield building STS to extend the Completion Time for 20 when the shield building is inoperable while in Modes 4 or 3 following a refueling outage and 21 prior to criticality.
22 23 1.1 Shield Building Discussion 24 25 Some Westinghouse and Combustion Engineering plant designs refer to the shield building 26 using plant-specific terminology, such as the enclosure building and the secondary containment.
27 For simplicity, throughout this safety evaluation (SE), the STS term shield building is used.
28 29 The STS shield building is a concrete structure that surrounds the steel containment vessel.
30 Between the containment vessel and the shield building inner wall is an annular space that 31 collects containment leakage that may occur following an accident. The shield building in part 32 ensures that the release of radioactive material from the containment atmosphere is restricted to 33 the leakage paths and associated leakage rates assumed in the accident analyses. The annular 34 space also allows for periodic inspection of the outer surface of the containment.
35 36 1 *NUREG-1431, Standard Technical Specifications, Westinghouse Plants, Volume 1, Specifications, and Volume 2, Bases, Revision 5, September 2021 (ML21259A155 and ML21259A159, respectively).
- NUREG-1432, Standard Technical Specifications, Combustion Engineering Plants, Volume 1, Specifications, and Volume 2, Bases, Revision 5, September 2021 (ML21258A421 and ML21258A424, respectively).
1.2 Description of the Current Requirements and the Proposed Change 1
2 Current STS shield building operability requirements 3
4 NUREG1431, Specification 3.6.8, Shield Building (Dual and Ice Condenser), requires the 5
shield building to be operable in Modes 1, 2, 3, and 4.
6 7
NUREG1432, Specification 3.6.11, "Shield Building (Dual)," requires the shield building to 8
be operable in Modes 1, 2, 3, and 4.
9 10 In both these specifications, if the shield building is inoperable, it must be restored to operable 11 status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The STS Bases for these specifications explain that 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is a 12 reasonable Completion Time considering the limited leakage design of containment and the low 13 probability of a design-basis accident occurring during this time period.
14 15 During a refueling outage, sections of the shield building boundary are removed to allow access 16 to the containment equipment hatch. At the end of the outage after the equipment hatch is 17 installed, restoring the shield building boundary is among the last activities performed prior to 18 entering Mode 4, which places restoration of the shield building on or near the outage critical 19 path.
20 21 Proposed change to STS shield building operability requirements 22 23 Following a refueling outage and prior to criticality, the decay heat generation and the 24 radionuclide inventory are significantly reduced compared to full power operation. As a result, a 25 longer Completion Time to restore the shield building to operable status in Modes 4 and 3 after 26 a refueling and prior to criticality is proposed. TSTF-601, Section 2, Detailed Description, 27 describes the proposed STS change to address an inoperable shield building under these 28 conditions. In particular, the STS shield building specifications would be revised to add a new 29 Action A, as shown below, that applies when the shield building is inoperable while in Mode 3 or 30 4 following refueling and prior to criticality (Mode 2) with a Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 31 restore the shield building to operable status:
32 33 A. ----------NOTE------------
Only applicable if MODE 2 has not been entered following refueling.
Shield building inoperable in MODE 3 or 4 following refueling.
A.1 Restore shield building to OPERABLE status.
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 34 The existing Condition A, which states, Shield Building inoperable, is renamed Condition B 35 and modified to state, Shield building inoperable for reasons other than Condition A. The 36 renamed Condition B Required Action and Completion Time are unaffected. Existing Action B is 37 renamed Action C but otherwise unchanged.
38
2.0 REGULATORY EVALUATION
1 2
As described in the Commissions Final Policy Statement on Technical Specifications 3
Improvements for Nuclear Power Reactors (58 FR 39132, dated July 22, 1993), [t]he new STS 4
should include greater emphasis on human factors principles in order to add clarity and 5
understanding to the text of the STS, and provide improvements to the Bases Section of the 6
Technical Specifications which provides the purpose for each requirement in the specification.
7 The improved vendor-specific STS were developed and issued by the NRC in September 1992.
8 9
The Summary Section of the Final Policy Statement on Technical Specifications Improvements 10 for Nuclear Power Reactors states, in part:
11 12 Implementation of the Policy Statement through implementation of the improved 13 STS is expected to produce an improvement in the safety of nuclear power 14 plants through the use of more operator-oriented Technical Specifications, 15 improved Technical Specification Bases, reduced action statement induced plant 16 transients, and more efficient use of NRC and industry resources.
17 18 Section IV, The Commission Policy, of the Final Policy Statement on Technical Specifications 19 Improvements for Nuclear Power Reactors states, in part:
20 21 The purpose of Technical Specifications is to impose those conditions or 22 limitations upon reactor operation necessary to obviate the possibility of an 23 abnormal situation or event giving rise to an immediate threat to the public health 24 and safety by identifying those features that are of controlling importance to 25 safety and establishing on them certain conditions of operation which cannot be 26 changed without prior Commission approval.
27 28
[T]he Commission will also entertain requests to adopt portions of the 29 improved STS [(e.g., TSTF-601)], even if the licensee does not adopt all STS 30 improvements. The Commission encourages all licensees who submit 31 Technical Specification related submittals based on this Policy Statement to 32 emphasize human factors principles.
33 34 In accordance with this Policy Statement, improved STS have been developed 35 and will be maintained for each NSSS [nuclear steam supply system] owners 36 group. The Commission encourages licensees to use the improved STS as the 37 basis for plant-specific Technical Specifications. [I]t is the Commission intent 38 that the wording and Bases of the improved STS be used to the extent 39 practicable.
40 41 The Final Policy Statement on Technical Specifications Improvements for Nuclear Power 42 Reactors provides the following description of the scope and the purpose of the STS Bases:
43 44 Each LCO [limiting condition for operation], Action, and Surveillance 45 Requirement should have supporting Bases. The Bases should at a minimum 46 address the following questions and cite references to appropriate licensing 47 documentation (e.g., Updated Final Safety Analysis Report (FSAR), Topical 48 Report) to support the Bases.
49 50
- 1. What is the justification for the Technical Specification, i.e., which Policy 1
Statement criterion requires it to be in the Technical Specifications?
2 3
- 2. What are the Bases for each LCO, i.e., why was it determined to be the lowest 4
functional capability or performance level for the system or component in 5
question necessary for safe operation of the facility and, what are the reasons for 6
the Applicability of the LCO?
7 8
- 3. What are the Bases for each Action, i.e., why should this remedial action be 9
taken if the associated LCO cannot be met; how does this Action relate to other 10 Actions associated with the LCO; and what justifies continued operation of the 11 system or component at the reduced state from the state specified in the LCO for 12 the allowed time period?
13 14
- 4. What are the Bases for each Safety Limit?
15 16
- 5. What are the Bases for each Surveillance Requirement and Surveillance 17 Frequency; i.e., what specific functional requirement is the surveillance designed 18 to verify? Why is this surveillance necessary at the specified frequency to assure 19 that the system or component function is maintained, that facility operation will be 20 within the Safety Limits, and that the LCO will be met?
21 22 Note: In answering these questions the Bases for each number (e.g., Allowable 23 Value, Response Time, Completion Time, Surveillance Frequency), state, 24 condition, and definition (e.g., operability) should be clearly specified. As an 25 example, a number might be based on engineering judgment, past experience, 26 or PSA [probabilistic safety assessment] insights; but this should be clearly 27 stated.
28 29 The regulations in Title 10 of the Code of Federal Regulations (10 CFR) paragraph 50.36(a)(1) 30 require that:
31 32 Each applicant for a license authorizing operation of a utilization facility shall 33 include in his application proposed technical specifications in accordance with 34 the requirements of this section. A summary statement of the bases or reasons 35 for such specifications, other than those covering administrative controls, shall 36 also be included in the application, but shall not become part of the technical 37 specifications.
38 39 The regulations in 10 CFR 50.36(b) require that:
40 41 Each license authorizing operation of a utilization facility will include 42 technical specifications. The technical specifications will be derived from the 43 analyses and evaluation included in the safety analysis report, and amendments 44 thereto, submitted pursuant to [10 CFR] 50.34 [Contents of applications; 45 technical information]. The Commission may include such additional technical 46 specifications as the Commission finds appropriate.
47 48 The categories of items required to be in the TS are listed in 10 CFR 50.36(c). The regulation 49 at 10 CFR 50.36(c)(2) requires that technical specifications include LCOs. Per 10 CFR 50 50.36(c)(2)(i), LCOs are the lowest functional capability or performance levels of equipment 51 required for safe operation of the facility. The regulation also requires that when an LCO of a 1
nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action 2
permitted by the TS until the condition can be met.
3 4
The NRC staffs guidance for the review of TS is in NUREG-0800, Standard Review Plan for 5
the Review of Safety Analysis Reports for Nuclear Power Plants: LWR [Light -Water Reactor]
6 Edition (SRP), Chapter 16.0, Technical Specifications, Revision 3, dated March 2010 7
(ML100351425). As described therein, as part of the regulatory standardization effort, the NRC 8
staff has prepared STS for each of the LWR nuclear designs.
9 10
3.0 TECHNICAL EVALUATION
11 12 The regulatory framework the NRC staff used to determine the acceptability of the proposed 13 change consists of the requirements and guidance listed in Section 2 of this SE. The NRC 14 staffs review determined whether the proposed change to the STS met the standards for 15 technical specifications (TS) categories in 10 CFR 50.36(c)(2), as well as conformed to the Final 16 Policy Statement on Technical Specifications Improvements for Nuclear Power Reactors. In 17 addition, the NRC staff reviewed the proposed STS changes for technical clarity and 18 consistency with the existing STS requirements for customary terminology and formatting.
19 20 3.1 Evaluation of New Condition A 21 22 As described in Section 1.2 of this SE, TSTF601 proposed a new Condition A. New 23 Condition A addresses situations where the shield building is inoperable while in Mode 4 24 or Mode 3 following refueling and before criticality (Mode 2).
25 26 TSTF601 states that this change is reasonable given the differences in the plant conditions 27 under the proposed Action compared to the plant conditions at full power. The NRC staff 28 assessed the differences in plant conditions described in TSTF601 such as energy in the core 29 and radionuclide inventory. In addition, the NRC staff assessed the containment and entering 30 the shield building specifications Applicability with the LCO not met.
31 32 3.1.1 Energy in the Core 33 34 TSTF601 assessed the energy in the reactor core that would be present under new 35 Condition A, in part, as follows:
36 37 In order to use the proposed 72-hour Completion Time, the reactor will have 38 been shut down for refueling, which takes at least 14 days. ANSI/ANS5.1, 39 Decay Heat Power in Light Water Reactors, indicates that after a 2-week 40 shutdown, the decay heat from fission products would be approximately 41 one-quarter of one percent of the full power heat generation. In addition, during 42 the preceding refueling outage approximately one-third of the core will have been 43 replaced with new, unirradiated fuel. This will further reduce the heat being 44 produced by the core. As a result, the energy in the core under the proposed 45 conditions would be less than that assumed for the [10 CFR 50] Appendix K 46 LOCA analysis by approximately three orders of magnitude.
47 48 The NRC staff reviewed the TSTF601 assessment of energy in the reactor core present under 49 new Condition A. The NRC staff concludes that nuclear energy in the reactor core present 50 under new Condition A is much lower when compared to atpower conditions, given the 1
reduction in decay heat and replacement of roughly one-third of the core.
2 3
Therefore, based on the above, the NRC staff finds the proposed new Condition A is acceptable 4
in part because of the lower nuclear energy in the reactor.
5 6
3.1.2 Accident Dose Consequence Analysis 7
8 TSTF601 assesses the radionuclide inventory in the reactor that would be present under new 9
Condition A, in part, as follows:
10 11 Approximately one-third of the core will be new, unirradiated fuel resulting in a 12 significant reduction of the radioactive material available for release from the core 13 in accident conditions. Also, during the refueling outage, shorter-lived 14 radioisotopes in the irradiated fuel have been reduced due to decay. For 15 example, Iodine-131 (a significant contributor to dose) has a half-life of 8 days 16 and will have been reduced in activity by almost a factor of 4 [four] during a 17 hypothetical 14-day shutdown. These factors reduce the radioactive material 18 available to be released into the shield building, also supporting a longer 19 Completion Time for the proposed conditions.
20 21 The NRC staff reviewed the TSTF601 assessment of radionuclides in the reactor core present 22 under new Condition A. As stated in Regulatory Position 3 in NRC Regulatory Guide 23 (RG) 1.183, Alternate Radiological Source Terms for Evaluating Design Basis Accidents at 24 Nuclear Power Reactors, July 2000 (ML003716792), the core inventory used in design-basis 25 accident loss of coolant accident analysis requires the licensee to assume that the fission 26 products in the reactor core are based on maximum full power operation of the core, and a 27 period of irradiation of sufficient duration to allow all the activity of the dose-significant 28 radionuclides to reach equilibrium or maximum values. The NRC staff concludes that 29 radionuclide inventory available for release in the reactor core present under new Condition A 30 would be significantly lower when compared to atpower maximum hypothetical accident 31 conditions, given the reduction in radionuclide activity due to decay and replacement of roughly 32 one-third of the core.
33 34 The transport of radionuclides during the new Condition A would be reduced with the 35 significantly lower energy in the core under the proposed condition. With the Appendix K LOCA 36 analysis under the new Condition A showing that the energy in the core is approximately three 37 orders of magnitude lower than the energy at full power, all pathways to the control room and 38 the environment would have a reduced release. Transport of the source term would be reduced 39 due to the lower reliance on engineered safety features to remove decay heat, and lower decay 40 heat reducing motive force causing primary containment leakage would also result in a lower 41 accident dose consequence.
42 43 Multiple plant systems are also required to be operable in Modes 4 and 3 that would significantly 44 lower any radioactive release in the event of an accident while in the proposed Action A, 45 including the primary containment, the containment isolation valves, and the shield building 46 ventilation system. The control room operators would also be protected by the control room 47 emergency filtration system.
48 49 Therefore, based on the above, the NRC staff finds the extension of the Completion Time 50 from 24 to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> proposed in the new Condition A is acceptable with respect to a radiological 51 consequences analysis due to (1) the reduction in radioactive material available for release, (2) 1 the operability requirements for other plant systems, and (3) the significantly reduced transport 2
of radionuclides from all release paths to the control room and environment.
3 4
3.1.3 Containment 5
6 TSTF601 points to the current NUREG1431 and NUREG1432 Action Bases for an inoperable 7
shield building. The NUREGs state, in part, that the Completion Time is reasonable considering 8
the limited leakage design of the containment.
9 10 The containment structure and its penetrations establish the leakage limiting boundary for the 11 containment function. Maintaining the containment operable when required in Modes 1 12 through 4 limits the leakage of fission product radioactivity from the containment to the 13 environment during a design-basis accident.
14 15 The STS provide containment surveillance requirements to assure that the necessary quality of 16 the containment and its penetrations are maintained, and that containment operation will be 17 within safety limits (e.g., leakage). Leakage testing is performed in accordance with the 18 Containment Leakage Rate Testing Program (a specification in the administrative controls 19 portion of the STS). This STS program addresses compliance with 10 CFR 50, Appendix J. In 20 addition, when the proposed new Condition A is applicable, the containment is required to be 21 operable.
22 23 Therefore, based on the above, the NRC staff finds the proposed new Condition A is 24 acceptable, in part, because the STS contain specifications designed to ensure operability of 25 containment prior to entering Mode 4.
26 27 3.1.4 Entering the Applicability with the LCO Not Met 28 29 The proposed change would permit a licensee to enter Modes 4 and 3 following a refueling 30 outage and prior to criticality before completion of the surveillance requirements needed to 31 establish the operability of the shield building.
32 33 NUREG1431 and NUREG1432 Surveillance Requirement 3.0.4 established the requirement 34 that all applicable Surveillances must be met before entry into a Mode or other specified 35 condition in the LCOs Applicability. This specification ensures that system and component 36 operability requirements are met before entry into Modes or other specified conditions in the 37 Applicability for which these systems and components ensure safe operation of the unit.
38 However, a provision in the NUREGs addresses the situation when an LCO is not met due to 39 Surveillances not having been met. Under this situation, entry into a Mode or other specified 40 condition in the Applicability shall only be made in accordance with LCO 3.0.4.
41 42 TSTF601 Section 3.3, Entering the Applicability with the LCO Not Met, explains that, under 43 the proposed change, licensees would apply LCO 3.0.4.b to enter Mode 4 and Mode 3 with the 44 shield building inoperable due to a Surveillance (i.e., shield building annulus negative pressure 45 limit) not met. LCO 3.0.4.b permits entry into the Applicability after performance of a risk 46 assessment addressing inoperable systems and components, consideration of the results, 47 determination of the acceptability of entering the Mode or other specified condition in the 48 Applicability, and establishment of risk management actions, if appropriate. The LCO 3.0.4.b 49 risk assessment must consider all inoperable TS equipment, such as the containment, 50 containment isolation valves, the shield building ventilation system, and the control room 51 emergency filtration system. The risk assessment must also consider other conditions such as 1
severe weather and likelihood of weather-generated missiles. The risk assessments will be 2
conducted using the procedures and guidance endorsed by Regulatory Guide (RG) 1.160, 3
Monitoring the Effectiveness of Maintenance at Nuclear Power Plants, Revision 4 4
(ML18220B281). RG 1.160 endorses the guidance in Section 11 of Nuclear Energy Institute, 5
Nuclear Management Resources Council (NUMARC), NUMARC 93-01, Revision 4F, Industry 6
Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants, 7
(ML18120A069).
8 9
The NRC staff reviewed the TSTF601 information about entering the Applicability of an LCO 10 with the LCO not met. The NRC staff notes that the STS allow continued operation with the 11 shield building inoperable in Mode 1 for the duration of the Completion Time. Since this is 12 allowable, and since in general the risk impact in that particular Mode bounds the risk of 13 transitioning into and through the applicable Modes in the Applicability of the LCO, the use of 14 the LCO 3.0.4.b allowance would be acceptable, as long as the risk is assessed and managed 15 as stated above.
16 17 Therefore, based on the above, the NRC staff finds the proposed new Condition A is acceptable 18 in part because of the requirement to perform a risk assessment (LCO 3.0.4.b) to determine the 19 acceptability of entering the Applicability for the shield building LCO with the LCO not met.
20 21 3.1.5 Summary 22 23 Based on the information provided in TSTF601 and the NRC staff evaluation above (SE 24 Sections 3.1.1 through 3.1.4), the NRC staff concludes that the proposed Action (new 25 Condition A) is reasonable given the differences in the plant conditions under the proposed 26 Action when compared to full power. In particular, when operating at full power the current STS 27 Bases describes 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as a reasonable Completion Time in the event shield building 28 operability is not maintained considering the limited leakage design of containment and the low 29 probability of a design-basis accident occurring during this time period. NRC staff considers 30 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as a reasonable Completion Time for the following reasons: (1) the limited leakage 31 design of containment, (2) the low probability of a design-basis accident occurring during this 32 same time period, and (3) the lower energy conditions in the reactor resulting in a significant 33 reduction in radionuclide transport coupled with the reduction in radionuclide inventory available 34 for release in Modes 4 and 3 following a refueling and before criticality.
35 36 The regulation at 10 CFR 50.36(c)(2) states, in part, that when an LCO of a nuclear reactor is 37 not met, the licensee shall shut down the reactor or follow any remedial action permitted by the 38 TS until the condition can be met. The proposed change provides a remedial action to be taken 39 when the LCO is not met, and, therefore, the NRC staff finds that 10 CFR 50.36(c)(2) will 40 continue to be met.
41 42 3.2 Evaluation of Changes to Existing Actions 43 44 The proposed change renamed the existing Condition A, which states, Shield Building 45 inoperable, to Condition B and modified it to state, Shield building inoperable for reasons other 46 than Condition A. The renamed Condition B Required Action and Completion Time are 47 unaffected. Existing Action B is renamed Action C but otherwise unchanged.
48 The NRC staff finds these changes acceptable because they are conforming changes resulting 1
from the new Condition A and do not alter the way the TS are implemented when the shield 2
building is inoperable for reasons other than Condition A.
3 3.3 STS Change Consistency 4
The NRC staff reviewed the proposed STS changes for technical clarity and consistency 5
with the existing requirements for customary terminology and formatting. The wording of 6
the new Action for the shield building is modeled on an existing allowance (Action A) in the 7
NUREG-1431 and NUREG1432 specifications for the auxiliary feedwater (AFW) system, which 8
permits a longer Completion Time for an inoperable turbine driven AFW pump in Mode 3 9
following refueling if Mode 2 has not been entered. The NRC staff concludes that the TSTF601 10 proposed change to the shield building STS is consistent with existing STS requirements for 11 customary terminology and formatting in accordance with SRP Chapter 16.0 and is, therefore, 12 acceptable.
13 3.4 Consideration of Changes to the STS Bases 14 The NRC staff reviewed the TSTF601, Revision 1, proposed changes to the STS Bases for 15 NUREG-1431 and NUREG1432. As discussed in Section 2.0 of this SE, the Final Policy 16 Statement on Technical Specifications Improvements for Nuclear Power Reactors describes the 17 scope and purpose of the STS Bases. It does so by listing five questions the STS Bases must 18 address. While the STS Bases must address these questions, not every question will be 19 relevant to every change to the STS Bases. The second, fourth, and fifth questions are not 20 relevant to this evaluation because the STS changes proposed in TSTF601, Revision 1, as 21 evaluated above, do not affect the LCO or its Applicability Bases, safety limits, or surveillance 22 requirements. In addition, because the proposed change only affects Actions, the Policy 23 Statement criterion that applies to the LCO is not affected and the first question is not relevant 24 to this evaluation. The proposed STS Bases support new and revised action statements; 25 therefore, only the third question is relevant to the changes.
26 Traveler TSTF601 Bases, in part, describe that new Action A allows the shield building to be 27 inoperable for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> instead of the 24-hour Completion Time in Condition B. In addition, the 28 Bases clarified that the 72-hour Completion Time was reasonable in MODE 3 or 4 immediately 29 following a refueling when the reactor has not been critical because of the reduced decay heat 30 generation and radionuclide inventory, the limited leakage design of the containment, the 31 Operable TS systems in the applicable Modes, and the low probability of an event requiring the 32 shield building.
33 The NRC staff finds the proposed STS Bases changes to be acceptable because the Bases for 34 the new and revised action statements adequately address Question 3 of the Final Policy 35 Statement on TS, ensuring that 10 CFR 50.36 will continue to be met.
36 37 3.5 Reportability 38 39 Traveler TSTF601 Section 3.6, Reportability, referenced information described within 40 NUREG1022, Event Report Guidelines, 10 CFR 50.72 and 50.73. The NRC staff considers 41 this information to be outside the scope of the TSTF601 review. As such, the NRC staff did not 42 review or evaluate the information regarding event report guidelines provided in TSTF601 43 Section 3.6.
44 1
4.0 CONCLUSION
2 3
The NRC staff concludes that there is reasonable assurance that plants adopting TSTF-601 will 4
continue to ensure that when the shield building LCO is not met, the licensee shall shut down 5
the reactor or follow any remedial action permitted by the TS until the condition can be met.
6 Therefore, the NRC staff finds that the proposed changes to the STS are acceptable because 7
they continue to meet the requirements of 10 CFR 50.36(c)(2) and provide protection to the 8
health and safety of the public.
9 10 Principal Contributors:
Clint Ashley, NRR/DSS/STSB 11 Steve Smith, NRR/DSS/STS 12 Sean Meighan, NRR/DRA/ARCB 13 Ahsan Salman, NRR 14 Derek Scully, NRR/DSS/SCPB 15 16 Date: August 4, 2025 17