ML25357A075

Evaluation of Proposed Changes

ML25357A075
Person / Time
Site:	Dresden, Peach Bottom, Clinton, Quad Cities, LaSalle
Issue date:	12/23/2025
From:	Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation
Shared Package
ML25357A073	List: ML25357A075 ML25357A076 ML25357A077 RS-25-164, Constellation - License Amendment Request to Eliminate Technical Specification for Automatic MSIV Closure on High Temperature and Add New Technical Specification, Main Steam Line (MSL) Area Temperature
References
RS-25-164
Download: ML25357A075 (0)

Text

ATTACHMENT 1a License Amendment Request Clinton Power Station, Unit 1 Docket No. 50-461 EVALUATION OF PROPOSED CHANGES

Subject:

License Amendment Request to Revise Technical Specification 3.3.6.1, Primary Containment and Drywell Isolation Instrumentation, and Add New Technical Specification 3.7.8, Main Steam Line (MSL) Area Temperature 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedents 4.3 No Significant Hazards Consideration 4.4 Conclusions

6.0 REFERENCES

1.0

SUMMARY

DESCRIPTION In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises TS to eliminate the requirement for automatic main steam line (MSL) isolation based on the temperature in the area around the MSL. In lieu of automatic isolation, a new specification, "Main Steam Line (MSL) Area Temperature," is proposed that requires manual action when the MSL area temperature is above the limit.

2.0 DETAILED DESCRIPTION The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, Main Steam Tunnel Temperature - High, Trip Function and Trip Function 1.f, Main Steam Line Turbine Building Temperature - High, and inserting the word "Deleted" in Table 3.3.6.1-1 for each deleted Trip Function. Deletion of Functions 1.e and 1.f does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.8, Main Steam Line (MSL) Area Temperature. The new LCO 3.7.8 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.8-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Functions 1.e and 1.f in LCO 3.3.6.1, respectively. The proposed change also adds a new corresponding SR 3.7.8.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.8-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limits specified in Table 3.7.8-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The existing leak detection instrumentation will be modified to remove the automatic MSL Isolation Trip Function; all other functions will remain unchanged.

3.0 TECHNICAL EVALUATION

The Main Steam Tunnel (MST) and Main Steam Line Turbine Building (MSLTB) are monitored by dual-element thermocouples for sensing high ambient temperature in all these areas. The temperature elements are located or shielded so that they are sensitive to air temperature only and not to radiated heat from hot piping or equipment. Increases in ambient temperature indicate leakage of reactor coolant into the area. The monitors located in the MST and Turbine Building have sensitivities suitable for detection of increases in ambient air temperature which are equivalent to reactor coolant leakage into the monitored areas of 25 gpm. The temperature trip setpoints are a function of room size and the type of ventilation provided. These monitors provide alarm and indication in the main control room and trip the isolation logic to cause closure of appropriate system isolation valves on indication of excessive MSL leakage.

The intent of the preemptive feature is to identify a steam line leak before the leakage rate reaches the threshold associated with a critical crack sizeone that could lead to a complete pipe rupture in the system. At CPS, the critical crack length for the main steam piping, as shown in USAR Figure 5.2-13, equates to approximately 300 gpm. Detecting leaks at a rate of 25 gpm, regardless of season, provides ample margin for early detection and allows operators to manually isolate the main steam line after confirming the condition, well before reaching the critical crack threshold. It is important to note that this automatic leak-before-break detection and isolation function is not necessary to meet any design basis event requirements.

CPS TS Table 3.3.6.1-1 has four functions and will continue to provide automatic Main Steam Line Isolation:

1.a.

Reactor Vessel Water Level - Low Low Low - Level 1 1.b.

Main Steam Line Pressure - Low 1.c.

Main Steam Line Flow - High 1.d Condenser Vacuum - Low The MST Temperature instrumentation and logic is not required to mitigate any design basis event and credit for this isolation instrumentation is not taken in any transient or accident analysis in Updated Safety Analysis Report (USAR) Chapter 15. Bounding analyses are performed for large breaks, such as MSL breaks that solely credit the automatic MSL high flow isolation. The MST Temperature isolation and reactor vessel low water level and low steam pressure isolations provide a diverse isolation function to the credited MSL high flow isolation.

This function does not require an automatic isolation of the MSLs on MST Area high temperature to assure plant safety. Given the purpose of the function, the consequences of an automatic reactor scram due to closure of the MSIVs is unwarranted.

The deletion of functions 1.e and 1.f is acceptable because MSL isolation would continue to be maintained by TS 3.3.6.1 functions 1.a through 1.d. The proposed TS 3.7.8 would require a plant shutdown if a leak is detected, and function 1.a through 1.d, which are not being revised by this License Amendment Request (LAR), would continue to provide Main Steam Line Isolation.

As an alternative, the proposed TS 3.7.8 will ensure that an MSL pressure boundary leak in the MST and Turbine Building will be promptly detected, and appropriate actions will be taken. The TS 3.7.8 Actions apply if any MSL Area Temperature in Table 3.7.8-1 is exceeded. It requires immediate action to determine if there is leakage from the MSL pressure boundary.

The proposed SR 3.7.8.1 requires verification that MSL Area maximum temperature is maintained less than or equal to the limits specified in Table 3.7.8-1. The Frequency is controlled under the SFCP, and the initial Frequency will be every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. As stated in SR 3.0.1, SRs must be met between performances of the Surveillance. If the MSL Area maximum temperature exceeds the limits specified in Table 3.7.8-1, operators will be alerted to take manual action.

If leakage from the MSL pressure boundary is detected or if the periodic verification is not performed, the actions require a plant shutdown. The plant must be brought to MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The proposed times are consistent with the requirements of similar specifications and are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

If elevated MSL Area temperature is determined to not be due to leakage from the MSL pressure boundary and remains above the limits specified in Table 3.7.8-1, the Actions require verification every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that there is no leakage from the MSL pressure boundary. During Normal power operation, the monitored MST area has elevated radiation levels and adverse environmental conditions. The 12-hour Completion Time balances the small likelihood of a MSL pressure boundary leak occurring since the last verification against the risks of exposing workers to the radiological and environmental conditions to perform the verification.

The Applicability of LCO 3.7.8 is MODES 1, 2, and 3. In MODES 1, 2, and 3, a Design Basis Accident (DBA) could result in the release of radioactive material into the MST if there is a leak in the MSLs. In MODES 4 and 5, the probability and consequences of a DBA with fission product release into the MST are reduced because of the pressure and temperature limitations in these conditions. Therefore, maintaining MST temperature within limits is not required in MODE 4 or 5. The proposed Applicability is the same as the current Functions 1.e and 1.f.

Indicated MSL Area Temperature may be elevated due to reasons other than an MSL pressure boundary leak, such as hot weather, reduced turbine building ventilation airflow or area cooling, and faulty temperature detectors. Verification will determine whether the elevated temperature is due to leakage from the MSL pressure boundary or another reason. Operations personnel are trained to perform the actions required to verify if leakage exists from the MSL pressure boundary, and no additional training or new operator actions will be required to perform the actions of TS 3.7.8.

Pursuant to 10 CFR 50.49, Constellation Energy implements an Environmental Qualification (EQ) program under Procedure CC-AA-203, Environmental Qualification Program, Revision 18.

EQ concerns will be managed under that procedure and in conjunction with the Corrective Action Program (CAP). CPS uses procedure 9000.01D001, Control Room Surveillance Log -

Mode 1, 2, 3 Data Sheet to check steam tunnel temperatures daily. Procedure 9000.01,

Control Room Surveillance Log requires the control room to contact Engineering if any temperature limit is exceeded. Procedure OP-AA-108-115, Operability Determinations, Revision 28, directs an Operability Evaluation (OpEval) be performed by Engineering upon discovery of a condition that affects compliance with 10 CFR 50.49. The OpEval must show that subsequent failure of the equipment, if under accident conditions, will not result in a consequential failure (i.e. loss of specified safety function). Additionally, if elevated temperatures within the Main Steam Line Tunnel area reach the condition for entry into the new proposed MSL Area Temperature LCO, Constellation procedure PI-AA-120 also requires entry of the condition into CAP. Pursuant to PI-AA-120, unplanned LCO entry in the condition of applicability for failure to meet TS surveillance acceptance criteria shall result in an evaluation which considers equipment performance and impacts. Therefore, impacts to EQ will be identified and managed per EQ procedures and CAP. No new EQ zones will be created as a result of the proposed change.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria The following applicable regulations and regulatory requirements were reviewed in the development of this submittal:

10 CFR 50.36: (1) installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary; (2) a process variable, design feature, or operating restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; (3) a structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; and (4) a structure, system, or component which operating experience or probabilistic risk assessment (PRA) has shown to be significant to public health and safety. As a result, TS requirements which satisfy any of the criteria in 10 CFR 50.36 must be retained in the TS.

MSL pressure boundary leakage in the MSL Area is monitored to protect the assumptions of accident dose analysis. Therefore, the requirement to monitor MSL Area maximum temperatures is treated as an operating restriction that is an initial condition of a DBA or transient analysis that either assumes the failure of, or presents a challenge to, the integrity of a fission product barrier and is maintained in the TS per Criterion 2.

Revising the requirement from automatic isolation to manual detection and shutdown does not affect the ability to satisfy Criterion 2.

10 CFR Part 50 Appendix A General Design Criteria (GDC) 30: Components which are part of the Reactor Coolant Pressure Boundary (RCPB) shall be designed, fabricated, erected, and tested to the highest quality standards practical. Means shall be provided for detecting and, to the extent practical, identifying the location of the source of reactor coolant leakage.

Means are provided for detecting reactor coolant leakage. The leak detection system consists of sensors and instruments to detect, annunciate, and, in some cases, isolate the RCPB from potential hazardous leaks before predetermined limits are exceeded. As described in USAR Section 5.2.5.1.3, small leaks are detected by temperature and pressure changes, increased frequency of sump pump operation, and measurement of airborne radioactivity in the primary containment atmosphere. In addition to these means of detection, large leaks are detected by flow rates in process lines and changes in reactor water level. The allowable leakage rates are based on the predicted and experimentally determined behavior of cracks in pipes, the ability to make up coolant system leakage, the normally expected background leakage due to equipment design, and the detection capability of the various sensors and instruments. The total leakage rate limit is established so that, in the absence of normal AC power concurrent with a loss of feedwater supply, makeup capabilities are provided by the Reactor Core Isolation Cooling (RCIC) system. While the leak detection system provides protection from small leaks, the Emergency Core Cooling System (ECCS) network provides protection for the complete range of discharges from ruptured pipes. Thus, protection is provided for the full spectrum of possible discharges. The RCPB and the leak detection system meet the requirements of GDC 30.

10 CFR Part 50 Appendix A GDC 54: Piping systems penetrating primary reactor containment shall be provided with leak detection, isolation, and containment having redundancy, reliability, and performance capabilities which reflect the importance to safety of isolating these piping systems.

The CPS design incorporates various and diverse leak detection and containment isolation features consistent with the requirements of GDC 54. It is proposed that the Main Steam Tunnel Temperature - High and Main Steam Line Turbine Building Temperature - High Trip Functions be removed from the TS for containment isolation instrumentation. Appropriate automatic isolations for MSIVs are still retained consistent with GDC 54 by other diverse leakage detection features.

4.2 Precedents By letter dated October 13, 2021, Southern Nuclear Operating Company (SNC) submitted a license amendment request for Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2 (Hatch) titled, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21286A595). The amendment was approved on May 20, 2022 (ADAMS Accession No. ML22101A094).

Following the approval of the Hatch amendment, on June 13, 2024, Limerick Generating Station submitted License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9 (ADAMS Accession No. ML24165A264). The amendment was approved on July 29, 2024 (ADAMS Accession No. ML24204A071).

The Hatch Turbine Building Area Temperature - High, Trip Function served the same purpose as the LGS "Turbine Enclosure Main Steam Line Tunnel Temperature, Trip Function. Both Trip Functions actuated the MSIVs on high temperature indications around the MSL. Both functions

were intended to automatically shut down the plant on small indications of leakage on the MSLs.

In both cases, actuation of the function would cause a complicated reactor scram.

CPSs Main Steam Tunnel Area Temperature - High and Main Steam Line Turbine Building Temperature - High Trip Functions also serves the same purpose to isolate the MSIVs automatically upon detection of small leaks on the MSLs. Like Hatch and Limerick, complete actuation of Main Steam Line Isolation logic due to Main Steam Line Tunnel Temp High or Main Steam Line Turbine Building Temp High will result in a complicated reactor scram.

4.3 No Significant Hazards Consideration In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the TS for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS),

Units 2 and 3.

The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, Main Steam Tunnel Temperature - High, Trip Function and Trip Function 1.f, Main Steam Line Turbine Building Temperature - High, and inserting the word "Deleted" in Table 3.3.6.1-1 for each deleted Trip Function. Deletion of Functions 1.e and 1.f does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.8, Main Steam Line (MSL) Area Temperature. The new LCO 3.7.8 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.8-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Functions 1.e and 1.f in LCO 3.3.6.1. The proposed change also adds a new corresponding SR 3.7.8.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.8-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limits specified in Table 3.7.8-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

CEG has evaluated the proposed changes, using the criteria in 10 CFR 50.92, Issuance of amendment, and has determined that the proposed changes do not involve a significant hazards consideration. The following information is provided to support a finding of no significant hazards consideration.

1. Do the proposed changes involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No

The proposed changes do not alter any of the previously evaluated accidents in the USAR. The proposed changes do not affect any of the initiators of previously evaluated accidents in a manner that would increase the likelihood of the event. The proposed change also eliminates the automatic Main Steam Isolation Valve (MSIV) isolation function associated with MSL Area high temperature from the requirements of the Technical Specifications (TS) and creates TS requirements for MSL Area temperature monitoring in a new TS 3.7.8.

Automatic isolation of the MSIVs on MST high temperature is not an initiator of any accident previously evaluated. A manual plant shutdown initiated due to MSL leakage in the MST or Turbine Building is not an initiator of any accident previously evaluated.

There is no credit taken in any licensing basis analysis for MSIV closure on MSL Area high temperature, and there are no calculations that credit the subject isolation function as a mitigative feature.

As a result, the likelihood of malfunction of an SSC is not increased. The capability and operation of the mitigation systems are not affected by the proposed changes. Thus, the mitigating systems will continue to be initiated and mitigate the consequences of an accident as assumed in the analysis of accidents previously evaluated.

Therefore, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Do the proposed changes create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No The proposed changes will not introduce any new operating modes, safety-related equipment lineups, accident scenarios, system interactions, or failure modes that would create a new or different type of accident. Failure of the system will have the same effect as the present design.

The proposed change eliminates the automatic MSIV isolation function associated with MSL Area high temperatures from the requirements of the TS and creates TS requirements for MSL Area temperature monitoring in a new LCO. Eliminating the automatic isolation of the MSIVs will not create a new or different kind of accident from those previously evaluated as an MSLB has been evaluated. Elimination of the automatic isolation function will not create a new failure mechanism as a plant shutdown continues to be required if an MSL leak is detected.

The proposed change from an MSIV isolation and subsequent scram to a manual shutdown will not create any credible new failure mechanisms, malfunctions, or accident initiators not considered in the design and licensing bases. An MSLB resulting from the failure to manually detect an MSL leak and shutdown the plant is unlikely but an MSLB has been evaluated in USAR Chapter 15 and is not a new type of accident.

Therefore, the proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Do the proposed changes involve a significant reduction in a margin of safety?

Response: No The proposed changes do not affect the accident source term, containment isolation, or radiological release assumptions used in evaluating the radiological consequences of any accident previously evaluated and are consistent with safety analysis assumptions and resultant consequences. The proposed changes do not impact reactor operating parameters or the functional requirements of the affected instrumentation systems. The remaining Functions in Table 3.3.6.1-1 will continue to provide protective system actuations. All design basis events, and the reliance on the protective system actuations will remain unchanged. No controlling numerical values for parameters established in the USAR or the license or Safety Limits are affected by the proposed changes.

Therefore, the proposed changes do not involve a significant reduction in a margin of safety.

Based on the above evaluation, CEG concludes that the proposed amendments present no significant hazards consideration under the standards set forth in 10 CFR 50.92, paragraph (c), and accordingly, a finding of "no significant hazards consideration" is justified.

4.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or the health and safety of the public.

5.0 ENVIRONMENTAL CONSIDERATION

CEG has determined that the proposed changes would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed changes do not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed changes meet the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, in accordance with 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed changes.

6.0 REFERENCES

1.

Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2, "Issuance of Amendments Nos. 315 and 260, Regarding Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" May 20, 2022 (ADAMS Accession No. ML22101A094).

2.

Limerick Generating Station Issuance of Amendments Nos. 263 and 255 Re: Technical Specifications for Main Steam Line Tunnel Temperature, July 29, 2024 (ADAMS Accession No. ML24204A071).

ATTACHMENT 1b License Amendment Request Dresden Nuclear Power Station Docket Nos. 50-237 and 50-249 EVALUATION OF PROPOSED CHANGES

Subject:

License Amendment Request to Revise Technical Specification 3.3.6.1, Primary Containment Isolation Instrumentation, and Add New Technical Specification 3.7.9, Main Steam Line (MSL) Area Temperature 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration 4.4 Conclusions

6.0 REFERENCES

1.0

SUMMARY

DESCRIPTION In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises Technical Specification (TS) to eliminate the requirement for automatic main steam line (MSL) isolation based on the temperature in the area around the MSL. In lieu of automatic isolation, a new specification, "Main Steam Line (MSL) Area Temperature," is proposed that requires manual action when the MSL area temperature is above the limit.

2.0 DETAILED DESCRIPTION The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, Main Steam Line Tunnel Temperature - High, and inserting the word "Deleted" in Table 3.3.6.1-1 for the deleted Trip Function. Deletion of Function 1.e does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.9, Main Steam Line (MSL) Area Temperature. The new LCO 3.7.9 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.9-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Function 1.e in LCO 3.3.6.1. The proposed change also adds a new corresponding SR 3.7.9.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.9-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, the MSL area maximum temperature exceeds the limit specified in Table 3.7.9-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The existing leak detection instrumentation will be modified to remove the automatic MSL Isolation Trip Function; all other functions will remain unchanged.

3.0 TECHNICAL EVALUATION

The Main Steam Line Tunnel TemperatureHigh Function receives input from 16 channels, four for each of the four tunnel areas. One channel from each steam tunnel area inputs to one of four trip strings. Two trip strings make up each trip system and both trip systems must trip to cause an isolation of all main steam isolation valves (MSIV)s, main steam line (MSL) drain valves, and recirculation sample isolation valves.

Main steam line tunnel (MSLT) temperature is provided to detect a leak in the RCPB in the steam tunnel and provides diversity to the high flow instrumentation. Temperature is sensed in four different areas of the steam tunnel above each main steam line. The isolation occurs when

a small leak has occurred in any one of the four areas. If the small leak is allowed to continue without isolation, offsite dose limits may be reached. However, credit for these instruments is not taken in any transient or accident analysis in the UFSAR, since bounding analyses are performed for large breaks, such as main steam line breaks (MSLBs).

MSL Isolation signals are initiated from temperature switches located in the four areas being monitored. Even though physically separated from each other, any temperature switch in any of the four areas is able to detect a leak. Therefore, sixteen channels of Main Steam Line Tunnel TemperatureHigh Function are available, but only eight channels (two channels in each of the four trip strings) are required to be OPERABLE to ensure that no single instrument failure can preclude the isolation function.

The Main Steam Line Tunnel TemperatureHigh Allowable Value is chosen to detect a leak of less than 1% rated steam flow.

The Main Steam Tunnel (MST) Temperature instrumentation and logic is not required to mitigate any design basis event and credit for this isolation instrumentation is not taken in any transient or accident analysis in UFSAR Chapter 15. Bounding analyses are performed for large breaks, such as MSL breaks that solely credit the automatic MSL high flow isolation. The MST Temperature isolation, along with the Reactor Vessel Water LevelLow Low and Main Steam Line PressureLow isolations provide a diverse isolation function to the credited Main Steam Line FlowHigh isolation. This function does not require an automatic isolation of the MSLs on MST Area high temperature to assure plant safety. Given the purpose of the function, the consequences of an automatic reactor scram due to closure of the MSIVs is unwarranted.

As an alternative, the proposed TS 3.7.9 will ensure that an MSL pressure boundary leak in the MST will be promptly detected, and appropriate actions will be taken.

The proposed LCO 3.7.9 requires that the MSL Area maximum temperature be less than or equal to the limits specified in Table 3.7.9-1. The leak detection isolation function is not required to satisfy any design basis event.

The Applicability of LCO 3.7.9 is MODES 1, 2, and 3. In MODES 1, 2, and 3, a Design Basis Accident (DBA) could result in the release of radioactive material into the MST if there is a leak in the MSLs. In MODES 4 and 5, the probability and consequences of a DBA with fission product release into the MST are reduced because of the pressure and temperature limitations in these conditions. Therefore, maintaining MST temperature within limits is not required in MODE 4 or 5.

The proposed SR 3.7.9.1 requires verification that MSL Area maximum temperature be less than or equal to the limits specified in Table 3.7.9-1. The Frequency is controlled under the SFCP, and the initial Frequency will be every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. As stated in SR 3.0.1, SRs must be met between performances of the Surveillance. If the MSL Area maximum temperature exceeds the limits specified in Table 3.7.9-1, operators will be alerted to take action.

The TS 3.7.9 Actions apply if any MSL Area temperature in Table 3.7.9-1 is exceeded. It requires immediate action to determine if there is leakage from the MSL pressure boundary.

MSL Area temperature may be elevated due to reasons other than an MSL pressure boundary leak, such as hot weather, reduced turbine building ventilation airflow or area cooling, and faulty temperature detectors. Verification will determine whether the elevated temperature is due to

leakage from the MSL pressure boundary or another reason. Operations personnel are trained to perform the actions required to verify if leakage exists from the MSL pressure boundary, and no additional training or new operator actions will be required to perform the actions of TS 3.7.9.

If the elevated temperature is determined to not be due to leakage from the MSL pressure boundary and while MSL Area maximum temperature exceeds the limits specified in Table 3.7.9-1, the Actions require verification every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that there is no leakage from the MSL pressure boundary. During Normal power operation, the monitored MST area has elevated radiation levels and adverse environmental conditions. The 12-hour Completion Time balances the small likelihood of a MSL pressure boundary leak occurring since the last verification against the risks of exposing workers to the radiological and environmental conditions to perform the verification.

If leakage from the MSL pressure boundary is detected or if the periodic verification is not performed, the actions require a plant shutdown. The plant must be brought to MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The proposed times are consistent with the requirements of similar specifications and are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

The following TS 3.3.6.1 functions will continue to provide automatic MSL isolation:

Reactor Vessel Water level - Low Low Main Steam Line Pressure - Low (MODE 1 Only)

Main Steam Line Pressure - Timer Main Steam Line Flow - High Pursuant to 10 CFR 50.49, Constellation Energy implements an Environmental Qualification (EQ) program under Procedure CC-AA-203, Environmental Qualification Program, Revision

18. EQ concerns will be managed through the station EQ procedures in conjunction with the Corrective Action Program (CAP). Procedure OP-AA-108-115, Operability Determinations, Revision 28, directs an Operational Evaluation (OpEval) be performed by EQ Engineering upon discovery of a condition that affects compliance with 10 CFR 50.49. The OpEval must show that subsequent failure of the equipment, if under accident conditions, will not result in a consequential failure (i.e. loss of specified safety function). As an enhancement, a modification to Dresden Procedure Appendix A, Unit Daily Surveillance Log, Revision 151, will include specific direction for the EQ Engineer to determine any deficient condition or program non-compliance if EQ parameters are exceeded and evaluate as necessary. Additionally, if elevated temperatures within the Main Steam Line Tunnel area reach the condition for entry into the new proposed MSL Area Temperature LCO, Constellation procedure PI-AA-120 also requires entry of the condition into CAP. Pursuant to PI-AA-120, unplanned LCO entry in the condition of applicability for failure to meet TS surveillance acceptance criteria shall result in an evaluation which considers equipment performance and impacts. Therefore, impacts to EQ will be identified and managed per EQ procedures and CAP. No new EQ zones will be created as a result of the proposed change.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria The following applicable regulations and regulatory requirements were reviewed in the development of this submittal:

10 CFR 50.36: (1) installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary; (2) a process variable, design feature, or operating restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; (3) a structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; and (4) a structure, system, or component which operating experience or probabilistic risk assessment (PRA) has shown to be significant to public health and safety. As a result, TS requirements which satisfy any of the criteria in 10 CFR 50.36 must be retained in the TS.

MSL pressure boundary leakage in the MSL Area is monitored to protect the assumptions of the accident dose analysis. Therefore, the requirement to monitor MSL Area maximum temperatures is treated as an operating restriction that is an initial condition of a DBA or transient analysis that either assumes the failure of, or presents a challenge to, the integrity of a fission product barrier and is maintained in the TS per Criterion 2. Revising the requirement from an automatic isolation to manual detection and shutdown does not affect the ability to satisfy Criterion 2.

10 CFR Part 50 Appendix A General Design Criteria (GDC) 30: Components which are part of the Reactor Coolant Pressure Boundary (RCPB) shall be designed, fabricated, erected, and tested to the highest quality standards practical. Means shall be provided for detecting and, to the extent practical, identifying the location of the source of reactor coolant leakage.

Means are provided for detecting reactor coolant leakage. The leak detection system consists of sensors and instruments to detect, annunciate, and, in some cases, isolate the RCPB from potential hazardous leaks before predetermined limits are exceeded. As described in UFSAR Section 5.2.6, small leaks are detected by temperature and pressure changes, and measurement of airborne radioactivity in the primary containment atmosphere. In addition to these means of detection, large leaks are detected by flow rates in process lines and changes in reactor water level. The allowable leakage rates are based on the predicted and experimentally determined behavior of cracks in pipes, the ability to make up coolant system leakage, the normally expected background leakage due to equipment design, and the detection capability of the various sensors and instruments. The total leakage rate limit is established so that, in the absence of normal AC power concurrent with a loss of feedwater supply, makeup capabilities are provided by the High Pressure Coolant Injection (HPCI) system. While the leak detection system provides protection from small leaks, the Emergency Core Cooling System (ECCS) network provides protection for the complete range of discharges from ruptured pipes. Thus, protection is provided for the full spectrum of possible discharges.

The original design of DNPS, Units 2 and 3, was reviewed and approved against the draft General Design Criteria (GDC) issued in July 1967. Updated Final Safety Analysis

Report (UFSAR), Section 3.1, "Conformance with NRC General Design Criteria,"

provides an assessment against the 70 draft GDC published in 1967 and concluded that the plant specific requirements are sufficiently similar to the Appendix A GDC.

Therefore, the equivalent draft GDC used at DNPS is functionally equivalent to 10 CFR 50 Appendix A, GDC 30.

10 CFR Part 50 Appendix A GDC 54: Piping systems penetrating primary reactor containment shall be provided with leak detection, isolation, and containment having redundancy, reliability, and performance capabilities which reflect the importance to safety of isolating these piping systems.

The DNPS design incorporates various and diverse leak detection and containment isolation features consistent with the requirements of GDC 54. It is proposed that the Main Steam Tunnel Temperature - High Function be removed from the TS for containment isolation instrumentation. Appropriate automatic isolations for MSIVs are still retained consistent with GDC 54 by other diverse leakage detection features.

4.2 Precedents By letter dated October 13, 2021, Southern Nuclear Operating Company (SNC) submitted a license amendment request for Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2 (Hatch) titled, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21286A595). The amendment was approved on May 20, 2022 (ADAMS Accession No. ML22101A094).

Following the approval of the Hatch amendment, on June 13, 2024, Limerick Generating Station submitted License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9 (ADAMS Accession No. ML24165A264). The amendment was approved on July 29, 2024 (ADAMS Accession No. ML24204A071).

The Hatch Turbine Building Area Temperature - High, Trip Function served the same purpose as the LGS "Turbine Enclosure Main Steam Line Tunnel Temperature, Trip Function. Both Trip Functions actuated the MSIVs on high temperature indications around the MSL. Both functions were intended to automatically shut down the plant on small indications of leakage on the MSLs.

In both cases, actuation of the function would cause a complicated reactor scram.

DNPS Main Steam Tunnel Area Temperature - High, Trip Function also serves the same purpose to isolate the MSIVs automatically upon detection of small leaks on the MSLs. Like Hatch and Limerick, actuation of this Trip Function included in this request would cause a complicated reactor scram.

4.3 No Significant Hazards Consideration In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2;

Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, Main Steam Line Tunnel Temperature - High, and inserting the word "Deleted" in Table 3.3.6.1-1 for the deleted Trip Function. Deletion of Function 1.e does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.9, Main Steam Line (MSL) Area Temperature. The new LCO 3.7.9 requires the MSL area maximum temperatures to be maintained less than or equal to the limits as specified in new Table 3.7.9-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Function 1.e in LCO 3.3.6.1. The proposed change also adds a new corresponding SR 3.7.9.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.9-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, the MSL area maximum temperature exceeds the limit specified in Table 3.7.9-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

CEG has evaluated the proposed changes, using the criteria in 10 CFR 50.92, Issuance of amendment, and has determined that the proposed changes do not involve a significant hazards consideration. The following information is provided to support a finding of no significant hazards consideration.

1. Do the proposed changes involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed changes do not alter any of the previously evaluated accidents in the UFSAR. The proposed changes do not affect any of the initiators of previously evaluated accidents in a manner that would increase the likelihood of the event. The proposed change also eliminates the automatic Main Steam Isolation Valve (MSIV) isolation function associated with MSL Area high temperature from the requirements of the Technical Specifications (TS) and creates TS requirements for MSL Area temperature monitoring in a new TS 3.7.9.

Automatic isolation of the MSIVs on MSL Area high temperature is not an initiator of any accident previously evaluated. A manual plant shutdown initiated due to MSL leakage in the MST or MSTLE is not an initiator of any accident previously evaluated. There is no credit taken in any licensing basis analysis for MSIV closure on MSL Area high temperature, and there are no calculations that credit the subject isolation function as a mitigative feature.

As a result, the likelihood of malfunction of an SSC is not increased. The capability and operation of the mitigation systems are not affected by the proposed changes. Thus, the

mitigating systems will continue to be initiated and mitigate the consequences of an accident as assumed in the analysis of accidents previously evaluated.

Therefore, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Do the proposed changes create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No The proposed changes will not introduce any new operating modes, safety-related equipment lineups, accident scenarios, system interactions, or failure modes that would create a new or different type of accident. Failure of the system will have the same effect as the present design.

The proposed change eliminates the automatic MSIV isolation function associated with MSL Area high temperatures from the requirements of the TS and creates TS requirements for MSL Area temperature monitoring in a new LCO. Eliminating the automatic isolation of the MSIVs will not create a new or different kind of accident from those previously evaluated as an MSLB has been evaluated. Elimination of the automatic isolation function will not create a new failure mechanism as a plant shutdown continues to be required if an MSL leak is detected.

The proposed change from an MSIV isolation and subsequent scram to a manual shutdown will not create any credible new failure mechanisms, malfunctions, or accident initiators not considered in the design and licensing bases. The unlikely failure to manually detect an MSL leak and shutdown the plant and that failure leading to a MSLB has already been evaluated and is not a new type of accident.

Therefore, the proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Do the proposed changes involve a significant reduction in a margin of safety?

Response: No The proposed changes do not affect the accident source term, containment isolation, or radiological release assumptions used in evaluating the radiological consequences of any accident previously evaluated and are consistent with safety analysis assumptions and resultant consequences. The proposed changes do not impact reactor operating parameters or the functional requirements of the affected instrumentation systems. The remaining Functions in Table 3.3.6.1-1 will continue to provide protective system actuations. All design basis events, and the reliance on the protective system actuations will remain unchanged. No controlling numerical values for parameters established in the UFSAR or the license or Safety Limits are affected by the proposed changes.

Therefore, the proposed changes do not involve a significant reduction in a margin of safety.

Based on the above evaluation, CEG concludes that the proposed amendments present no significant hazards consideration under the standards set forth in 10 CFR 50.92, paragraph (c), and accordingly, a finding of "no significant hazards consideration" is justified.

4.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or the health and safety of the public.

5.0 ENVIRONMENTAL CONSIDERATION

CEG has determined that the proposed changes would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed changes do not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed changes meet the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, in accordance with 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed changes.

6.0 REFERENCES

1.

Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" May 20, 2022 (ADAMS Accession No. ML22101A094).

2.

Limerick Generating Station License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9, July 29, 2024 (ADAMS Accession No. ML24204A071).

ATTACHMENT 1c License Amendment Request LaSalle County Station, Units 1 & 2 Docket Nos. 50-373 and 50-374 EVALUATION OF PROPOSED CHANGES

Subject:

License Amendment Request to Revise Technical Specification 3.3.6.1, "Primary Containment Isolation Instrumentation," and Add New Technical Specification 3.7.9, "Main Steam Line (MSL) Area Temperature" 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration 4.4 Conclusions

6.0 REFERENCES

1.0

SUMMARY

DESCRIPTION In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises Technical Specification (TS) to eliminate the requirement for automatic main steam line (MSL) isolation based on the temperature in the area around the MSL. In lieu of automatic isolation, a new specification, "Main Steam Line (MSL) Area Temperature," is proposed that requires manual action when the MSL area temperature is above the limit.

2.0 DETAILED DESCRIPTION The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, "Main Steam Line Tunnel Differential Temperature - High" and inserting the word "Deleted" in Table 3.3.6.1-1 for the deleted Trip Function. Deletion of Function 1.e does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.9, "Main Steam Line (MSL) Area Temperature." The new LCO 3.7.9 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.9-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Functions 1.e in LCO 3.3.6.1. The proposed change also adds a new corresponding SR 3.7.9.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.9-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limit specified in Table 3.7.9-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The existing leak detection instrumentation will be modified to remove the automatic MSL Isolation Trip Function; all other functions will remain unchanged.

3.0 TECHNICAL EVALUATION

The MSL tunnel is monitored by thermocouples for high ambient and differential area temperature. The thermocouples are positioned in the MSL tunnel so that they are screened from direct incident radiated heat and yet are still able to respond to the temperature of ambient air. All the thermocouples are terminated on digital recorders located in the main control room, which compute and display differential temperatures as well as the ambient temperatures.

Output relays from the recorders will initiate alarms and isolations (e.g., the detection system closes the Main Steam Isolation Valves [MSIVs] and MSL drain isolation valves and other

valves) when the associated temperatures exceed predefined setpoints. The thermocouples and recorders associated with the differential area temperatures in the MSL tunnel have sensitivities suitable for detection of increases in differential area temperature equivalent to reactor coolant leakage into the monitored areas of 100 gpm. The setpoint is a function of the large air flow in the MSL tunnel and the temperature in the MSL tunnel being affected by normal operational and outside ambient changes.

There are no isolations associated with MSL tunnel ambient temperature. The automatic isolation function for ambient temperature was removed in L1R07 and L2R07 to reduce spurious isolations of the MSLs. The alarm function for ambient temperature was retained for monitoring. The isolation function was removed from the TS under License Amendments 111 for Unit 1 and 96 for Unit 2 (ML021130125).

The purpose of the MSL tunnel differential temperature isolation function as part of the MSL leak detection system is to provide timely detection and isolation of small MSL leaks while maintaining sufficient margin above normal operating temperatures to avoid spurious isolation.

The MSL leak detection instrumentation is part of the MSIV Group 1 isolation logic and isolates the MSIVs and the MSL drain valves.

Differential Temperature - High is provided to detect a leak in a MSL and provides diversity to the high flow instrumentation. The isolation occurs when a very small leak has occurred. If the small leak is allowed to continue without isolation, offsite dose limits may be reached. However, credit for these instruments is not taken in any transient or accident analysis in Chapter 15 of the Updated Final Safety Analysis Report (UFSAR) since bounding analyses are performed for large breaks such as main steam line breaks (MSLBs). The MSLB accident analysis in Chapter 15 of the UFSAR solely credits the automatic MSL high flow isolation function.

The MSL isolation function does not require automatic isolation on MSL tunnel high differential temperature to assure plant safety due to other diverse TS functions that provide automatic isolation (i.e., low reactor vessel water level, low MSL pressure, and high MSL flow). Given the purpose of the MSL isolation function, the consequences of an automatic scram due to the closure of the MSIVs on high differential temperature is unwarranted.

As an alternative to the automatic action Function 1.e in Table 3.3.6.1-1 of TS 3.3.6.1, the proposed TS 3.7.9 will ensure that small MSL steam leaks are promptly detected, and the appropriate manual actions are taken.

The current Function 1.e allowable value of 66.4°F listed in Table 3.3.6.1-1 of TS 3.3.6.1 will be used for the proposed LCO 3.7.9 for MSL Tunnel Differential Temperature in Table 3.7.9-1.

The Applicability of LCO 3.7.9 will be MODES 1, 2, and 3. The proposed Applicability is the same as the as TS 3.3.6.1 Function 1.e. A design basis accident (DBA) could result in the release of radioactive material into the MSL tunnel if there is a leak in the MSLs. In MODES 4 and 5, the probability and consequences of a DBA with fission product release into the MSL tunnel are reduced because of the pressure and temperature limitations in these conditions.

Therefore, maintaining MSL tunnel temperature within limits is not required in MODES 4 or 5.

The proposed SR 3.7.9.1 requires verification that the MSL differential temperature is 66.4°F as shown on Table 3.7.9-1. The frequency is controlled under the SFCP with the initial frequency of every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. As stated in SR 3.0.1, SRs must be met between performances of

the surveillance. If the MSL differential temperature exceeds 66.4°F, operators will be alerted to take required actions.

The TS 3.7.9 Actions apply if the MSL tunnel differential temperature limits are exceeded. It requires immediate action to determine if there is leakage from the MSL pressure boundary.

The MSL tunnel differential temperature may be elevated due to reasons other than MSL pressure boundary leak, such as hot weather, reduced building ventilation airflow, and faulty temperature detectors. Verification will determine whether the elevated temperature is due to leakage from the MSL pressure boundary or another reason. Operations personnel are trained to perform proceduralized actions required to verify if leakage exists from the MSL pressure boundary. No additional training or new operator actions will be required to perform the actions of TS 3.7.9.

If the elevated temperature is determined to not be due to leakage from the MSL pressure boundary while MSL tunnel differential temperature exceeds the limits specified in TS Table 3.7.9-1, the actions require verification every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that there is no leakage from the MSL pressure boundary. The area monitored in the MSL tunnel area has elevated radiation levels and adverse environmental conditions. The 12-hour completion time balances the small likelihood of a MSL leak occurring since the last verification against the risks of exposing workers to the radiological and environmental conditions to perform the verification.

If leakage from the MSL pressure boundary is detected or if the periodic verification is not performed, the actions require a plant shutdown. The plant must be placed in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The proposed times are consistent with the requirements of similar specifications and are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

The following TS 3.3.6.1 functions will continue to provide automatic MSL isolation:

Function 1.a: Reactor Vessel Water level - Low Low Low, Level 1 Function 1.b: Main Steam Line Pressure - Low Function 1.c: Main Steam Line Flow - High Function 1.d: Condenser Vacuum - Low Pursuant to 10 CFR 50.49, Constellation Energy implements an Environmental Qualification (EQ) program under procedure CC-AA-203. EQ concerns will be managed through the station EQ procedures in conjunction with the Corrective Action Program (CAP). LaSalle procedures LOS-AA-S101 and LOS-AA-S201 require shift personnel to record the differential temperatures in the Main Steam Line Tunnel. If these temperatures go above the EQ threshold, the event is entered into LaSalles CAP. CAP will then direct engineering to assess the duration of the elevated temperatures. This assessment involves reviewing ambient temperature records and initiating updates to any impacted EQ qualification data. As an enhancement, an update to LOS-AA-101 and LOS-AA-201, Unit 1(2) Shiftly Surveillance, Revision 121, will include specific direction for the EQ Engineer to perform an evaluation if EQ parameters are exceeded.

Procedure OP-AA-108-115 also directs Operational Evaluation (OpEval) for EQ upon discovery of a condition that affects compliance with 10 CFR 50.49. Such an OpEval must show that subsequent failure of the equipment, if under accident conditions, will not result in a consequential failure (i.e. loss of specified safety function). Additionally, if elevated temperatures within the Main Steam Line Tunnel area reach the condition for entry into the new proposed

MSL Area Temperature LCO, Constellation procedure PI-AA-120 also requires entry of the condition into CAP. Pursuant to PI-AA-120, unplanned LCO entry in the condition of applicability for failure to meet TS surveillance acceptance criteria shall result in an evaluation which considers equipment performance and impacts. Therefore, impacts to EQ will be identified and managed per EQ procedures and CAP.

The proposed change improves plant safety by eliminating the potential for an unwarranted, complicated reactor scram while continuing to ensure that small MSL leaks are detected and appropriate actions are taken.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria The following applicable regulations and regulatory requirements were reviewed in the development of this submittal:

10 CFR 50.36: (1) installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary; (2) a process variable, design feature, or operating restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; (3) a structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; and (4) a structure, system, or component which operating experience or probabilistic risk assessment (PRA) has shown to be significant to public health and safety. As a result, TS requirements which satisfy any of the criteria in 10 CFR 50.36 must be retained in the TS.

MSL pressure boundary leakage in the MSL Area is monitored to protect the assumptions of the leakage dose analysis. Therefore, the requirement to monitor MSL Area maximum differential temperature is treated as an operating restriction that is an initial condition of a DBA or transient analysis that either assumes the failure of, or presents a challenge to, the integrity of a fission product barrier and is maintained in the TS per Criterion 2. Revising the requirement from an automatic isolation to manual detection and shutdown does not affect the ability to satisfy Criterion 2.

10 CFR Part 50 Appendix A General Design Criteria (GDC) 30: Components which are part of the Reactor Coolant Pressure Boundary (RCPB) shall be designed, fabricated, erected, and tested to the highest quality standards practical. Means shall be provided for detecting and, to the extent practical, identifying the location of the source of reactor coolant leakage.

Means are provided for detecting reactor coolant leakage. The leak detection system consists of sensors and instruments to detect, annunciate, and, in some cases, isolate the RCPB from potential hazardous leaks before predetermined limits are exceeded. As described in UFSAR Section 5.2.5.1.2, small leaks are detected by temperature and pressure changes, increased frequency of sump pump operation, and measurement of airborne radioactivity in the primary containment atmosphere. In addition to these

means of detection, large leaks are detected by flow rates in process lines and changes in reactor water level. The allowable leakage rates are based on the predicted and experimentally determined behavior of cracks in pipes, the ability to make up coolant system leakage, the normally expected background leakage due to equipment design, and the detection capability of the various sensors and instruments. The total leakage rate limit is established so that, in the absence of normal AC power concurrent with a loss of feedwater supply, makeup capabilities are provided by the Reactor Core Isolation Cooling (RCIC) system. While the leak detection system provides protection from small leaks, the Emergency Core Cooling System (ECCS) network provides protection for the complete range of discharges from ruptured pipes. Thus, protection is provided for the full spectrum of possible discharges. The RCPB and the leak detection system meet the requirements of GDC 30.

10 CFR Part 50 Appendix A GDC 54: Piping systems penetrating primary reactor containment shall be provided with leak detection, isolation, and containment having redundancy, reliability, and performance capabilities which reflect the importance to safety of isolating these piping systems.

The LSCS design incorporates various and diverse leak detection and containment isolation features consistent with the requirements of GDC 54. It is proposed that the Main Steam Line Tunnel Differential Temperature - High Trip Function be removed from the TS for containment isolation instrumentation. Appropriate automatic isolations for MSIVs are still retained consistent with GDC 54 by other diverse leakage detection features.

4.2 Precedents By letter dated October 13, 2021, Southern Nuclear Operating Company (SNC) submitted a license amendment request for Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2 (Hatch) titled, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21286A595). The amendment was approved on May 20, 2022 (ADAMS Accession No. ML22101A094).

Following the approval of the Hatch amendment, on June 13, 2024, Limerick Generating Station submitted "License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9" (ADAMS Accession No. ML24165A264). The amendment was approved on July 29, 2024 (ADAMS Accession No. ML24204A071).

The Hatch "Turbine Building Area Temperature - High," Trip Function served the same purpose as the LGS "Turbine Enclosure Main Steam Line Tunnel Temperature," Trip Function. Both Trip Functions actuated the MSIVs on high temperature indications around the MSL. Both functions were intended to automatically shut down the plant on small indications of leakage on the MSLs.

In both cases, actuation of the function would cause a complicated reactor scram.

LSCSs "Main Steam Line Tunnel Differential Temperature - High" Trip Function also serves the same purpose to isolate the MSIVs automatically upon detection of small leaks on the MSLs.

Like Hatch and Limerick, actuation of the LSCS Trip Function included in this request would cause a complicated reactor scram.

4.3 No Significant Hazards Consideration In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, "Main Steam Line Tunnel Differential Temperature - High" and inserting the word "Deleted" in Table 3.3.6.1-1 for the deleted Trip Function. Deletion of Function 1.e does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.9, "Main Steam Line (MSL) Area Temperature." The new LCO 3.7.9 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.9-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Functions 1.e in LCO 3.3.6.1. The proposed change also adds a new corresponding SR 3.7.9.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.9-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limit specified in Table 3.7.9-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

CEG has evaluated the proposed changes, using the criteria in 10 CFR 50.92, "Issuance of amendment," and has determined that the proposed changes do not involve a significant hazards consideration. The following information is provided to support a finding of no significant hazards consideration.

1. Do the proposed changes involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed changes do not alter any of the previously evaluated accidents in the UFSAR. The proposed changes do not affect any of the initiators of previously evaluated accidents in a manner that would increase the likelihood of the event. The proposed change also eliminates the automatic Main Steam Isolation Valve (MSIV) isolation function associated with MSL tunnel high differential temperature from the requirements of the Technical Specifications (TS) and creates TS requirements for MSL Area temperature monitoring in a new TS 3.7.9.

Automatic isolation of the MSIVs on MSL Area high differential temperature is not an initiator of any accident previously evaluated. A manual plant shutdown initiated due to MSL leakage in the MSL tunnel is not an initiator of any accident previously evaluated.

There is no credit taken in any licensing basis analysis for MSIV closure on MSL Area high differential temperature, and there are no calculations that credit the subject isolation function as a mitigative feature.

As a result, the likelihood of malfunction of an SSC is not increased. The capability and operation of the mitigation systems are not affected by the proposed changes. Thus, the mitigating systems will continue to be initiated and mitigate the consequences of an accident as assumed in the analysis of accidents previously evaluated.

Therefore, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Do the proposed changes create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No The proposed changes will not introduce any new operating modes, safety-related equipment lineups, accident scenarios, system interactions, or failure modes that would create a new or different type of accident. Failure of the system will have the same effect as the present design.

The proposed change eliminates the automatic MSIV isolation function associated with MSL Area high differential temperatures from the requirements of the TS and creates TS requirements for MSL Area temperature monitoring in a new LCO. Eliminating the automatic isolation of the MSIVs will not create a new or different kind of accident from those previously evaluated as an MSLB has been evaluated. Elimination of the automatic isolation function will not create a new failure mechanism as a plant shutdown continues to be required if an MSL leak is detected.

The proposed change from an MSIV isolation and subsequent scram to a manual shutdown will not create any credible new failure mechanisms, malfunctions, or accident initiators not considered in the design and licensing bases. The unlikely failure to manually detect an MSL leak and shutdown the plant and that failure leading to a MSLB has already been evaluated and is not a new type of accident.

Therefore, the proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Do the proposed changes involve a significant reduction in a margin of safety?

Response: No The proposed changes do not affect the accident source term, containment isolation, or radiological release assumptions used in evaluating the radiological consequences of any accident previously evaluated and are consistent with safety analysis assumptions and resultant consequences. The proposed changes do not impact reactor operating parameters or the functional requirements of the affected instrumentation systems. The remaining Functions in Table 3.3.6.1-1 will continue to provide protective system actuations. All design basis events, and the reliance on the protective system actuations

will remain unchanged. No controlling numerical values for parameters established in the UFSAR or the license or Safety Limits are affected by the proposed changes.

Therefore, the proposed changes do not involve a significant reduction in a margin of safety.

Based on the above evaluation, CEG concludes that the proposed amendments present no significant hazards consideration under the standards set forth in 10 CFR 50.92, paragraph (c), and accordingly, a finding of "no significant hazards consideration" is justified.

4.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or the health and safety of the public.

5.0 ENVIRONMENTAL CONSIDERATION

CEG has determined that the proposed changes would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed changes do not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed changes meet the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, in accordance with 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed changes.

6.0 REFERENCES

1.

Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" May 20, 2022 (ADAMS Accession No. ML22101A094).

2.

Limerick Generating Station "License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9", July 29, 2024 (ADAMS Accession No. ML24204A071).

ATTACHMENT 1d License Amendment Request Peach Bottom Atomic Power Station, Unit 2 Docket No. 50-277 EVALUATION OF PROPOSED CHANGES

Subject:

License Amendment Request to Revise Technical Specification 3.3.6.1, Primary Containment Isolation Instrumentation, and Add New Technical Specification 3.7.8, Main Steam Line (MSL) Area Temperature 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration 4.4 Conclusions

6.0 REFERENCES

1.0

SUMMARY

DESCRIPTION In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises Technical Specification (TS) to eliminate the requirement for automatic main steam line (MSL) isolation based on the temperature in the area around the MSL. In lieu of automatic isolation, a new specification, "Main Steam Line (MSL) Area Temperature," is proposed that requires manual action when the MSL area temperature is above the limit.

2.0 DETAILED DESCRIPTION The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, Turbine Building Main Steam Line Tunnel Temperature - High, Trip Function and 1.f, Reactor Building Main Steam Line Tunnel Temperature - High. The word "Deleted" shall be inserted to preserve formatting in Table 3.3.6.1-1 for each deleted Trip Function. Deletion of Functions 1.e and 1.f does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.8, Main Steam Line (MSL) Area Temperature. The new LCO 3.7.8 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.8-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Functions 1.e and 1.f, in LCO 3.3.6.1, respectively. The proposed change also adds a new corresponding SR 3.7.8.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.8-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limits specified in Table 3.7.8-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The existing leak detection instrumentation will be modified to remove the automatic MSL Isolation Trip Function; all other functions will remain unchanged.

3.0 TECHNICAL EVALUATION

The Main Steam Tunnel (MST) Temperature is monitored by 16 Resistance Temperature Detectors (RTDs) for sensing high ambient temperatures located along the main steam lines between the drywell wall and the turbine building. The temperature elements are located or shielded so that they are sensitive to air temperature only and not to radiated heat from hot piping or equipment. Increases in ambient temperature indicate leakage of reactor coolant into the area. The instruments located in the MST have sensitivities suitable for detection of

increases in ambient air temperature to detect main steam line leakage from 1 to 10 percent of rated steam flow. The temperature trip setpoints are a function of room size and the type of ventilation provided. These monitors provide alarm, indication, and recording in the main control room, and actuate the isolation logic to close select isolation valves (e.g., the MSL monitors close the Main Steam Isolation Valves [MSIV] and Main Steam Line Drains.

The large number of available indications and their dispersed arrangement near the steam lines provide confidence that a significant break would be detected rapidly and accurately in the MST.

Temperature - High is provided to detect a leak in a main steam line and provides diversity to the high flow instrumentation. Temperature limits will be reached when a very small leak has occurred. If the small leak is allowed to continue without isolation, offsite dose limits may be reached. However, credit for these instruments is not taken in any transient or accident analysis in the UFSAR, since bounding analyses are performed for large breaks such as MSLBs.

The purpose of the MSL Area Temperature isolation function is to provide timely detection and isolation of small MSL leaks while maintaining sufficient margin above normal operating temperatures to avoid spurious isolation. The MSL Area Temperature instrumentation is part of the MSIV Group I isolation logic and isolates the normally open MSIVs.

The MST Temperature instrumentation and logic is not required to mitigate any design basis event and credit for this isolation instrumentation is not taken in any transient or accident analysis in Updated Final Safety Analysis Report (UFSAR) Chapter 14. Bounding analyses are performed for large breaks, such as MSL breaks that solely credit the automatic MSL high flow isolation. The MST Temperature isolation and reactor vessel low level and low steam pressure isolations provide a diverse isolation function to the credited MSL high flow isolation. This function does not require an automatic isolation of the MSLs on MST Area high temperature to assure plant safety. Given the purpose of the function, the consequences of an automatic reactor scram due to closure of the MSIVs is unwarranted.

As an alternative, the proposed TS 3.7.8 will ensure that an MSL pressure boundary leak in the MST will be promptly detected, and appropriate actions will be taken.

The proposed LCO 3.7.8 requires that the MSL Area maximum temperature be less than or equal to the limits specified in Table 3.7.8-1. The leak detection isolation function is not required to satisfy any design basis event.

The Applicability of LCO 3.7.8 is MODES 1, 2, and 3. In MODES 1, 2, and 3, a Design Basis Accident (DBA) could result in the release of radioactive material into the MST if there is a leak in the MSLs. In MODES 4 and 5, the probability and consequences of a DBA with fission product release into the MST are reduced because of the pressure and temperature limitations in these conditions. Therefore, maintaining MST temperature within limits is not required in MODE 4 or 5. The proposed Applicability is the same as the current Functions 1.e and 1.f.

The proposed SR 3.7.8.1 requires verification that MSL Area maximum temperature be less than or equal to the limits specified in Table 3.7.8-1. The Frequency is controlled under the SFCP, and the initial Frequency will be every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. As stated in SR 3.0.1, SRs must be met between performances of the Surveillance. If the MSL Area maximum temperature exceeds the limits specified in Table 3.7.8-1, operators will be alerted to take action.

The TS 3.7.8 Actions apply if any MSL Area temperature in Table 3.7.8-1 is exceeded. It requires immediate action to determine if there is leakage from the MSL pressure boundary.

MSL Area temperature may be elevated due to reasons other than an MSL pressure boundary leak, such as hot weather, reduced turbine building ventilation airflow or area cooling, and faulty temperature detectors. Verification will determine whether the elevated temperature is due to leakage from the MSL pressure boundary or another reason. Operations personnel are trained to perform the actions required to verify if leakage exists from the MSL pressure boundary, and no additional training or new operator actions will be required to perform the actions of TS 3.7.8.

If the elevated temperature is determined to not be due to leakage from the MSL pressure boundary and while MSL Area maximum temperature exceeds the limits specified in Table 3.7.8-1, the Actions require verification every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that there is no leakage from the MSL pressure boundary. During Normal power operation, the monitored MST area has elevated radiation levels and adverse environmental conditions. The 12-hour Completion Time balances the small likelihood of a MSL pressure boundary leak occurring since the last verification against the risks of exposing workers to the radiological and environmental conditions to perform the verification.

If leakage from the MSL pressure boundary is detected or if the periodic verification is not performed, the actions require a plant shutdown. The plant must be brought to MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The proposed times are consistent with the requirements of similar specifications and are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

The following TS 3.3.6.1 functions will continue to provide automatic MSL isolation:

Reactor Vessel Water level - Low Low Low (Level 1)

Main Steam Line Pressure - Low Main Steam Line Flow - High Pursuant to 10 CFR 50.49, Constellation Energy implements an Environmental Qualification (EQ) program under procedure CC-AA-203. EQ concerns will be managed through the station EQ procedures in conjunction with the Corrective Action Program (CAP). Peach Bottom procedure CC-PB-203-1001 requires the EQ engineer to perform a periodic review of ambient temperature data and revision of qualification data. Procedure OP-AA-108-115 also directs Operational Evaluation (OpEval) for EQ upon discovery of a condition that affects compliance with 10 CFR 50.49. Such an OpEval must show that subsequent failure of the equipment, if under accident conditions, will not result in a consequential failure (i.e. loss of specified safety function). As an enhancement, Peach Bottom is also modifying procedure ST-O-098-00D(N)-

2(3), Common Daily Surveillance Log, to include specific direction to perform an evaluation if EQ parameters are exceeded. Additionally, if elevated temperatures within the Main Steam Line Tunnel area reach the condition for entry into the new proposed MSL Area Temperature LCO, Constellation procedure PI-AA-120 also requires entry of the condition into CAP. Pursuant to PI-AA-120, unplanned LCO entry in the condition of applicability for failure to meet TS surveillance acceptance criteria shall result in an evaluation which considers equipment performance and impacts. Therefore, impacts to EQ will be identified and managed per EQ procedures and CAP. No new EQ zones will be created as a result of the proposed change.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria The following applicable regulations and regulatory requirements were reviewed in the development of this submittal:

10 CFR 50.36: (1) installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary; (2) a process variable, design feature, or operating restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; (3) a structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; and (4) a structure, system, or component which operating experience or probabilistic risk assessment (PRA) has shown to be significant to public health and safety. As a result, TS requirements which satisfy any of the criteria in 10 CFR 50.36 must be retained in the TS.

MSL pressure boundary leakage in the MST Area is monitored to protect the assumptions of the accident dose analysis. Therefore, the requirement to monitor MSL Area maximum temperatures is treated as an operating restriction that is an initial condition of a DBA or transient analysis that either assumes the failure of, or presents a challenge to, the integrity of a fission product barrier and is maintained in the TS per Criterion 2. Revising the requirement from an automatic isolation to manual detection and shutdown does not affect the ability to satisfy Criterion 2.

10 CFR Part 50 Appendix A General Design Criteria (GDC) 30: Components which are part of the Reactor Coolant Pressure Boundary (RCPB) shall be designed, fabricated, erected, and tested to the highest quality standards practical. Means shall be provided for detecting and, to the extent practical, identifying the location of the source of reactor coolant leakage.

Means are provided for detecting reactor coolant leakage. The leak detection system consists of sensors and instruments to detect, annunciate, and, in some cases, isolate the RCPB from potential hazardous leaks before predetermined limits are exceeded. As described in UFSAR Section 4.10, Nuclear System Leakage Detection and Leakage rate Limits, conditions are detected by temperature and pressure changes, increased frequency of sump pump operation, and measurement of airborne radioactivity in the primary containment atmosphere. In addition to these means of detection, large leaks are detected by flow rates in process lines and changes in reactor water level. The allowable leakage rates are based on the predicted and experimentally determined behavior of cracks in pipes, the ability to make up coolant system leakage, the normally expected background leakage due to equipment design, and the detection capability of the various sensors and instruments. The total leakage rate limit is established so that, in the absence of normal AC power concurrent with a loss of feedwater supply, makeup capabilities are provided by the High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) system. While the leak detection system provides protection from small leaks, the Emergency Core Cooling System (ECCS) network provides protection for the complete range of discharges from ruptured pipes. Thus, protection is provided for the full spectrum of possible discharges. The RCPB and the leak detection system meet the requirements of GDC 30.

10 CFR Part 50 Appendix A GDC 54: Piping systems penetrating primary reactor containment shall be provided with leak detection, isolation, and containment having redundancy, reliability, and performance capabilities which reflect the importance to safety of isolating these piping systems.

During the construction licensing process for Peach Bottom Atomic Power Station Units 2 and 3, the units were evaluated against the then current Atomic Energy Commission (AEC) draft of the 27 General Design Criteria for Nuclear Power Plants (November, 1965). Updated Final Safety Analysis Report, Appendix H, CONFORMANCE TO AEC (NRC) CRITERIA, documents an assessment of the 70 draft General Design Criterion published in 1967. It was concluded that Units 2 and 3 conform with the intent of the AEC (NRC) proposed General Design Criteria for Nuclear Power Plants, 10CFR50, Appendix A, July 1967. Therefore, the equivalent draft GDC used at PBAPS is functionally equivalent to 10CFR50 Appendix A GDC 30 and GDC 54.

4.2 Precedents By letter dated October 13, 2021, Southern Nuclear Operating Company (SNC) submitted a license amendment request for Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2 (Hatch) titled, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21286A595). The amendment was approved on May 20, 2022 (ADAMS Accession No. ML22101A094).

Following the approval of the Hatch amendment, on June 13, 2024, Limerick Generating Station submitted License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9 (ADAMS Accession No. ML24165A264). The amendment was approved on July 29, 2024 (ADAMS Accession No. ML24204A071).

The Hatch Turbine Building Area Temperature - High, Trip Function served the same purpose as the LGS "Turbine Enclosure Main Steam Line Tunnel Temperature, Trip Function. Both Trip Functions actuated the MSIVs on high temperature indications around the MSL. Both functions were intended to automatically shut down the plant on small indications of leakage on the MSLs.

In both cases, actuation of the function would cause a complicated reactor scram.

PBAPS U2 & U3s Main Steam Tunnel Area Temperature - High, Trip Functions also serve the same purpose to isolate the MSIVs automatically upon detection of small leaks on the MSLs. Like Hatch and Limerick, actuation of the trip function included in this request would cause a complicated reactor scram.

4.3 No Significant Hazards Consideration In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, Turbine Building Main Steam Line Tunnel Temperature - High, Trip Function and 1.f, Reactor Building Main Steam Line Tunnel Temperature - High. The word "Deleted" shall be inserted to preserve formatting in Table 3.3.6.1-1 for each deleted Trip Function. Deletion of Functions 1.e and 1.f does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.8, Main Steam Line (MSL) Area Temperature. The new LCO 3.7.8 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.8-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Functions 1.e and 1.f, in LCO 3.3.6.1, respectively. The proposed change also adds a new corresponding SR 3.7.8.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.8-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limits specified in Table 3.7.8-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

CEG has evaluated the proposed changes, using the criteria in 10 CFR 50.92, Issuance of amendment, and has determined that the proposed changes do not involve a significant hazards consideration. The following information is provided to support a finding of no significant hazards consideration.

1. Do the proposed changes involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed changes do not alter any of the previously evaluated accidents in the UFSAR. The proposed changes do not affect any of the initiators of previously evaluated accidents in a manner that would increase the likelihood of the event. The proposed change also eliminates the automatic Main Steam Isolation Valve (MSIV) isolation function associated with MSL Area high temperature from the requirements of the Technical Specifications (TS) and creates TS requirements for MSL Area temperature monitoring in a new TS 3.7.8.

Automatic isolation of the MSIVs on MSL Area high temperature is not an initiator of any accident previously evaluated. A manual plant shutdown initiated due to MSL leakage in the MST is not an initiator of any accident previously evaluated. There is no credit taken in any licensing basis analysis for MSIV closure on MSL Area high temperature, and there are no calculations that credit the subject isolation function as a mitigative feature.

As a result, the likelihood of malfunction of an SSC is not increased. The capability and operation of the mitigation systems are not affected by the proposed changes. Thus, the mitigating systems will continue to be initiated and mitigate the consequences of an accident as assumed in the analysis of accidents previously evaluated.

Therefore, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Do the proposed changes create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No The proposed changes will not introduce any new operating modes, safety-related equipment lineups, accident scenarios, system interactions, or failure modes that would create a new or different type of accident. Failure of the system will have the same effect as the present design.

The proposed change eliminates the automatic MSIV isolation function associated with MSL Area high temperatures from the requirements of the TS and creates TS requirements for MSL Area temperature monitoring in a new LCO. Eliminating the automatic isolation of the MSIVs will not create a new or different kind of accident from those previously evaluated as an MSLB has been evaluated. Elimination of the automatic isolation function will not create a new failure mechanism as a plant shutdown continues to be required if an MSL leak is detected.

The proposed change from an MSIV isolation and subsequent scram to a manual shutdown will not create any credible new failure mechanisms, malfunctions, or accident initiators not considered in the design and licensing bases. The unlikely failure to manually detect an MSL leak and shutdown the plant and that failure leading to a MSLB has already been evaluated and is not a new type of accident.

Therefore, the proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Do the proposed changes involve a significant reduction in a margin of safety?

Response: No The proposed changes do not affect the accident source term, containment isolation, or radiological release assumptions used in evaluating the radiological consequences of any accident previously evaluated and are consistent with safety analysis assumptions and resultant consequences. The proposed changes do not impact reactor operating parameters or the functional requirements of the affected instrumentation systems. The remaining Functions in Table 3.3.6.1-1 will continue to provide protective system actuations. All design basis events, and the reliance on the protective system actuations will remain unchanged. No controlling numerical values for parameters established in the UFSAR or the license or Safety Limits are affected by the proposed changes.

Therefore, the proposed changes do not involve a significant reduction in a margin of safety.

Based on the above evaluation, CEG concludes that the proposed amendments present no significant hazards consideration under the standards set forth in 10 CFR 50.92, paragraph (c), and accordingly, a finding of "no significant hazards consideration" is justified.

4.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or the health and safety of the public.

5.0 ENVIRONMENTAL CONSIDERATION

CEG has determined that the proposed changes would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed changes do not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed changes meet the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, in accordance with 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed changes.

6.0 REFERENCES

1.

Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" May 20, 2022 (ADAMS Accession No. ML22101A094).

2.

Limerick Generating Station License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9, July 29, 2024 (ADAMS Accession No. ML24204A071).

ATTACHMENT 1e License Amendment Request Peach Bottom Atomic Power Station, Unit 3 Docket No. 50-278 EVALUATION OF PROPOSED CHANGES

Subject:

License Amendment Request to Revise Technical Specification 3.3.6.1, Primary Containment Isolation Instrumentation, and Add New Technical Specification 3.7.8, Main Steam Line (MSL) Area Temperature 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration 4.4 Conclusions

6.0 REFERENCES

1.0

SUMMARY

DESCRIPTION In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises Technical Specification (TS) to eliminate the requirement for automatic main steam line (MSL) isolation based on the temperature in the area around the MSL. In lieu of automatic isolation, a new specification, "Main Steam Line (MSL) Area Temperature," is proposed that requires manual action when the MSL area temperature is above the limit.

2.0 DETAILED DESCRIPTION The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, Main Steam Tunnel Temperature - High. The word "Deleted" shall be inserted to preserve formatting in Table 3.3.6.1-1 for each deleted Trip Function.

Deletion of Function 1.e does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.8, Main Steam Line (MSL) Area Temperature. The new LCO 3.7.8 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.8-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Function 1.e in LCO 3.3.6.1. The proposed change also adds a new corresponding SR 3.7.8.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.8-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limits specified in Table 3.7.8-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The existing leak detection instrumentation will be modified to remove the automatic MSL Isolation Trip Function; all other functions will remain unchanged.

3.0 TECHNICAL EVALUATION

The Main Steam Tunnel (MST) Temperature is monitored by 16 Resistance Temperature Detectors (RTDs) for sensing high ambient temperatures located along the main steam lines between the drywell wall and the turbine building. The temperature elements are located or shielded so that they are sensitive to air temperature only and not to radiated heat from hot piping or equipment. Increases in ambient temperature indicate leakage of reactor coolant into the area. The instruments located in the MST have sensitivities suitable for detection of increases in ambient air temperature to detect main steam line leakage from 1 to 10 percent of

rated steam flow. The temperature trip setpoints are a function of room size and the type of ventilation provided. These monitors provide alarm, indication, and recording in the main control room, and actuate the isolation logic to close select isolation valves (e.g., the MSL monitors close the Main Steam Isolation Valves [MSIV] and Main Steam Line Drains.

The large number of available indications and their dispersed arrangement near the steam lines provide confidence that a significant break would be detected rapidly and accurately in the MST.

Temperature - High is provided to detect a leak in a main steam line and provides diversity to the high flow instrumentation. Temperature limits will be reached when a very small leak has occurred. If the small leak is allowed to continue without isolation, offsite dose limits may be reached. However, credit for these instruments is not taken in any transient or accident analysis in the UFSAR, since bounding analyses are performed for large breaks such as MSLBs.

The purpose of the MSL Area Temperature isolation function is to provide timely detection and isolation of small MSL leaks while maintaining sufficient margin above normal operating temperatures to avoid spurious isolation. The MSL Area Temperature instrumentation is part of the MSIV Group I isolation logic and isolates the normally open MSIVs.

The MST Temperature instrumentation and logic is not required to mitigate any design basis event and credit for this isolation instrumentation is not taken in any transient or accident analysis in Updated Final Safety Analysis Report (UFSAR) Chapter 14. Bounding analyses are performed for large breaks, such as MSL breaks that solely credit the automatic MSL high flow isolation. The MST Temperature isolation and reactor vessel low level and low steam pressure isolations provide a diverse isolation function to the credited MSL high flow isolation. This function does not require an automatic isolation of the MSLs on MST Area high temperature to assure plant safety. Given the purpose of the function, the consequences of an automatic reactor scram due to closure of the MSIVs is unwarranted.

As an alternative, the proposed TS 3.7.8 will ensure that an MSL pressure boundary leak in the MST will be promptly detected, and appropriate actions will be taken.

The proposed LCO 3.7.8 requires that the MSL Area maximum temperature be less than or equal to the limits specified in Table 3.7.8-1. The leak detection isolation function is not required to satisfy any design basis event.

The Applicability of LCO 3.7.8 is MODES 1, 2, and 3. In MODES 1, 2, and 3, a Design Basis Accident (DBA) could result in the release of radioactive material into the MST if there is a leak in the MSLs. In MODES 4 and 5, the probability and consequences of a DBA with fission product release into the MST are reduced because of the pressure and temperature limitations in these conditions. Therefore, maintaining MST temperature within limits is not required in MODE 4 or 5. The proposed Applicability is the same as the current Function 1.e.

The proposed SR 3.7.8.1 requires verification that MSL Area maximum temperature be less than or equal to the limits specified in Table 3.7.8-1. The Frequency is controlled under the SFCP, and the initial Frequency will be every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. As stated in SR 3.0.1, SRs must be met between performances of the Surveillance. If the MSL Area maximum temperature exceeds the limits specified in Table 3.7.8-1, operators will be alerted to take action.

The TS 3.7.8 Actions apply if any MSL Area temperature in Table 3.7.8-1 is exceeded. It requires immediate action to determine if there is leakage from the MSL pressure boundary.

MSL Area temperature may be elevated due to reasons other than an MSL pressure boundary leak, such as hot weather, reduced turbine building ventilation airflow or area cooling, and faulty temperature detectors. Verification will determine whether the elevated temperature is due to leakage from the MSL pressure boundary or another reason. Operations personnel are trained to perform the actions required to verify if leakage exists from the MSL pressure boundary, and no additional training or new operator actions will be required to perform the actions of TS 3.7.8.

If the elevated temperature is determined to not be due to leakage from the MSL pressure boundary and while MSL Area maximum temperature exceeds the limits specified in Table 3.7.8-1, the Actions require verification every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that there is no leakage from the MSL pressure boundary. During Normal power operation, the monitored MST area has elevated radiation levels and adverse environmental conditions. The 12-hour Completion Time balances the small likelihood of a MSL pressure boundary leak occurring since the last verification against the risks of exposing workers to the radiological and environmental conditions to perform the verification.

If leakage from the MSL pressure boundary is detected or if the periodic verification is not performed, the actions require a plant shutdown. The plant must be brought to MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The proposed times are consistent with the requirements of similar specifications and are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

The following TS 3.3.6.1 functions will continue to provide automatic MSL isolation:

Reactor Vessel Water level - Low Low Low (Level 1)

Main Steam Line Pressure - Low Main Steam Line Flow - High Pursuant to 10 CFR 50.49, Constellation Energy implements an Environmental Qualification (EQ) program under procedure CC-AA-203. EQ concerns will be managed through the station EQ procedures in conjunction with the Corrective Action Program (CAP). Peach Bottom procedure CC-PB-203-1001 requires the EQ engineer to perform a periodic review of ambient temperature data and revision of qualification data. Procedure OP-AA-108-115 also directs Operational Evaluation (OpEval) for EQ upon discovery of a condition that affects compliance with 10 CFR 50.49. Such an OpEval must show that subsequent failure of the equipment, if under accident conditions, will not result in a consequential failure (i.e. loss of specified safety function). As an enhancement, Peach Bottom is also modifying procedure ST-O-098-00D(N)-

2(3), Common Daily Surveillance Log, to to include specific direction to perform an evaluation if EQ parameters are exceeded. Additionally, if elevated temperatures within the Main Steam Line Tunnel area reach the condition for entry into the new proposed MSL Area Temperature LCO, Constellation procedure PI-AA-120 also requires entry of the condition into CAP. Pursuant to PI-AA-120, unplanned LCO entry in the condition of applicability for failure to meet TS surveillance acceptance criteria shall result in an evaluation which considers equipment performance and impacts. Therefore, impacts to EQ will be identified and managed per EQ procedures and CAP. No new EQ zones will be created as a result of the proposed change.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria The following applicable regulations and regulatory requirements were reviewed in the development of this submittal:

10 CFR 50.36: (1) installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary; (2) a process variable, design feature, or operating restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; (3) a structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; and (4) a structure, system, or component which operating experience or probabilistic risk assessment (PRA) has shown to be significant to public health and safety. As a result, TS requirements which satisfy any of the criteria in 10 CFR 50.36 must be retained in the TS.

MSL pressure boundary leakage in the MST Area is monitored to protect the assumptions of the accident dose analysis. Therefore, the requirement to monitor MSL Area maximum temperatures is treated as an operating restriction that is an initial condition of a DBA or transient analysis that either assumes the failure of, or presents a challenge to, the integrity of a fission product barrier and is maintained in the TS per Criterion 2. Revising the requirement from an automatic isolation to manual detection and shutdown does not affect the ability to satisfy Criterion 2.

10 CFR Part 50 Appendix A General Design Criteria (GDC) 30: Components which are part of the Reactor Coolant Pressure Boundary (RCPB) shall be designed, fabricated, erected, and tested to the highest quality standards practical. Means shall be provided for detecting and, to the extent practical, identifying the location of the source of reactor coolant leakage.

Means are provided for detecting reactor coolant leakage. The leak detection system consists of sensors and instruments to detect, annunciate, and, in some cases, isolate the RCPB from potential hazardous leaks before predetermined limits are exceeded. As described in UFSAR Section 4.10, Nuclear System Leakage Detection and Leakage rate Limits, conditions are detected by temperature and pressure changes, increased frequency of sump pump operation, and measurement of airborne radioactivity in the primary containment atmosphere. In addition to these means of detection, large leaks are detected by flow rates in process lines and changes in reactor water level. The allowable leakage rates are based on the predicted and experimentally determined behavior of cracks in pipes, the ability to make up coolant system leakage, the normally expected background leakage due to equipment design, and the detection capability of the various sensors and instruments. The total leakage rate limit is established so that, in the absence of normal AC power concurrent with a loss of feedwater supply, makeup capabilities are provided by the High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) system. While the leak detection system provides protection from small leaks, the Emergency Core Cooling System (ECCS) network provides protection for the complete range of discharges from ruptured pipes. Thus, protection is provided for the full spectrum of possible discharges. The RCPB and the leak detection system meet the requirements of GDC 30.

10 CFR Part 50 Appendix A GDC 54: Piping systems penetrating primary reactor containment shall be provided with leak detection, isolation, and containment having redundancy, reliability, and performance capabilities which reflect the importance to safety of isolating these piping systems.

During the construction licensing process for Peach Bottom Atomic Power Station Units 2 and 3, the units were evaluated against the then current Atomic Energy Commission (AEC) draft of the 27 General Design Criteria for Nuclear Power Plants (November, 1965). Updated Final Safety Analysis Report, Appendix H, CONFORMANCE TO AEC (NRC) CRITERIA, documents an assessment of the 70 draft General Design Criterion published in 1967. It was concluded that Units 2 and 3 conform with the intent of the AEC (NRC) proposed General Design Criteria for Nuclear Power Plants, 10CFR50, Appendix A, July 1967. Therefore, the equivalent draft GDC used at PBAPS is functionally equivalent to 10CFR50 Appendix A GDC 30 and GDC 54.

4.2 Precedents By letter dated October 13, 2021, Southern Nuclear Operating Company (SNC) submitted a license amendment request for Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2 (Hatch) titled, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21286A595). The amendment was approved on May 20, 2022 (ADAMS Accession No. ML22101A094).

Following the approval of the Hatch amendment, on June 13, 2024, Limerick Generating Station submitted License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9 (ADAMS Accession No. ML24165A264). The amendment was approved on July 29, 2024 (ADAMS Accession No. ML24204A071).

The Hatch Turbine Building Area Temperature - High, Trip Function served the same purpose as the LGS "Turbine Enclosure Main Steam Line Tunnel Temperature, Trip Function. Both Trip Functions actuated the MSIVs on high temperature indications around the MSL. Both functions were intended to automatically shut down the plant on small indications of leakage on the MSLs.

In both cases, actuation of the function would cause a complicated reactor scram.

PBAPS U2 & U3s Main Steam Tunnel Area Temperature - High, Trip Functions also serve the same purpose to isolate the MSIVs automatically upon detection of small leaks on the MSLs. Like Hatch and Limerick, actuation of the trip function included in this request would cause a complicated reactor scram.

4.3 No Significant Hazards Consideration In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, Main Steam Tunnel Temperature - High. The word "Deleted" shall be inserted to preserve formatting in Table 3.3.6.1-1 for the deleted Trip Function.

Deletion of Function 1.e does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.8, Main Steam Line (MSL) Area Temperature. The new LCO 3.7.8 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.8-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Function 1.e in LCO 3.3.6.1. The proposed change also adds a new corresponding SR 3.7.8.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.8-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limits specified in Table 3.7.8-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

CEG has evaluated the proposed changes, using the criteria in 10 CFR 50.92, Issuance of amendment, and has determined that the proposed changes do not involve a significant hazards consideration. The following information is provided to support a finding of no significant hazards consideration.

1. Do the proposed changes involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed changes do not alter any of the previously evaluated accidents in the UFSAR. The proposed changes do not affect any of the initiators of previously evaluated accidents in a manner that would increase the likelihood of the event. The proposed change also eliminates the automatic Main Steam Isolation Valve (MSIV) isolation function associated with MSL Area high temperature from the requirements of the Technical Specifications (TS) and creates TS requirements for MSL Area temperature monitoring in a new TS 3.7.8.

Automatic isolation of the MSIVs on MSL Area high temperature is not an initiator of any accident previously evaluated. A manual plant shutdown initiated due to MSL leakage in the MST is not an initiator of any accident previously evaluated. There is no credit taken in any licensing basis analysis for MSIV closure on MSL Area high temperature, and there are no calculations that credit the subject isolation function as a mitigative feature.

As a result, the likelihood of malfunction of an SSC is not increased. The capability and operation of the mitigation systems are not affected by the proposed changes. Thus, the mitigating systems will continue to be initiated and mitigate the consequences of an accident as assumed in the analysis of accidents previously evaluated.

Therefore, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Do the proposed changes create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No The proposed changes will not introduce any new operating modes, safety-related equipment lineups, accident scenarios, system interactions, or failure modes that would create a new or different type of accident. Failure of the system will have the same effect as the present design.

The proposed change eliminates the automatic MSIV isolation function associated with MSL Area high temperatures from the requirements of the TS and creates TS requirements for MSL Area temperature monitoring in a new LCO. Eliminating the automatic isolation of the MSIVs will not create a new or different kind of accident from those previously evaluated as an MSLB has been evaluated. Elimination of the automatic isolation function will not create a new failure mechanism as a plant shutdown continues to be required if an MSL leak is detected.

The proposed change from an MSIV isolation and subsequent scram to a manual shutdown will not create any credible new failure mechanisms, malfunctions, or accident initiators not considered in the design and licensing bases. The unlikely failure to manually detect an MSL leak and shutdown the plant and that failure leading to a MSLB has already been evaluated and is not a new type of accident.

Therefore, the proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Do the proposed changes involve a significant reduction in a margin of safety?

Response: No The proposed changes do not affect the accident source term, containment isolation, or radiological release assumptions used in evaluating the radiological consequences of any accident previously evaluated and are consistent with safety analysis assumptions and resultant consequences. The proposed changes do not impact reactor operating parameters or the functional requirements of the affected instrumentation systems. The remaining Functions in Table 3.3.6.1-1 will continue to provide protective system actuations. All design basis events, and the reliance on the protective system actuations will remain unchanged. No controlling numerical values for parameters established in the UFSAR or the license or Safety Limits are affected by the proposed changes.

Therefore, the proposed changes do not involve a significant reduction in a margin of safety.

Based on the above evaluation, CEG concludes that the proposed amendments present no significant hazards consideration under the standards set forth in 10 CFR 50.92, paragraph (c), and accordingly, a finding of "no significant hazards consideration" is justified.

4.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or the health and safety of the public.

5.0 ENVIRONMENTAL CONSIDERATION

CEG has determined that the proposed changes would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed changes do not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed changes meet the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, in accordance with 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed changes.

6.0 REFERENCES

1.

Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" May 20, 2022 (ADAMS Accession No. ML22101A094).

2.

Limerick Generating Station License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9, July 29, 2024 (ADAMS Accession No. ML24204A071).

ATTACHMENT 1f License Amendment Request Quad Cities Nuclear Power Station, Units 1 & 2 Docket Nos. 50-254 and 50-265 EVALUATION OF PROPOSED CHANGES

Subject:

License Amendment Request to Revise Technical Specification 3.3.6.1, "Primary Containment Isolation Instrumentation," and Add New Technical Specification 3.7.10, "Main Steam Line (MSL) Area Temperature" 1.0

SUMMARY

DESCRIPTION 2.0 DETAILED DESCRIPTION

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration 4.4 Conclusions

6.0 REFERENCES

Quad Cities Nuclear Power Station, Units 1 & 2 f-Evaluation of Proposed Changes Page 1 of 7 1.0

SUMMARY

DESCRIPTION In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises Technical Specification (TS) to eliminate the requirement for automatic main steam line (MSL) isolation based on the temperature in the area around the MSL. In lieu of automatic isolation, a new specification, "Main Steam Line (MSL) Area Temperature," is proposed that requires manual action when the MSL area temperature is above the limit.

2.0 DETAILED DESCRIPTION The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, "Main Steam Line Tunnel Temperature - High," and inserting the word "Deleted" in Table 3.3.6.1-1 for the deleted Trip Function. Deletion of Function 1.e does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.10, "Main Steam Line (MSL) Area Temperature." The new LCO 3.7.10 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.10-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Functions 1.e in LCO 3.3.6.1. The proposed change also adds a new corresponding SR 3.7.10.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.10-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limits specified in Table 3.7.10-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The existing leak detection instrumentation will be modified to remove the automatic MSL Isolation Trip Function; all other functions will remain unchanged.

3.0 TECHNICAL EVALUATION

The Main Steam Tunnel (MST) and outboard MSIV room are monitored by bimetallic temperature switches for sensing high ambient temperature in all these areas. Increases in ambient temperature may indicate leakage of reactor coolant into the area. The switches located in the MST and MSIV room have sensitivities suitable for detection of leaks equivalent to between 1% and 10% rated steam flow. These switches trip the isolation logic to close selected isolation valves (e.g., the MST monitors close the Main Steam Isolation Valves [MSIV]

and MSL drain isolation valves and other valves).

The large number of switches and their dispersed arrangement near the steam lines provide confidence that a significant break would be detected rapidly and accurately in the MST.

Temperature - High is provided to detect a leak in a main steam line and provides diversity to the high flow instrumentation. Temperature limits will be reached when a very small leak has

Quad Cities Nuclear Power Station, Units 1 & 2 f-Evaluation of Proposed Changes Page 2 of 7 occurred. If the small leak is allowed to continue without isolation, offsite dose limits may be reached. However, credit for these instruments is not taken in any transient or accident analysis in the UFSAR, since bounding analyses are performed for large breaks such as Main Steam Line Breaks.

The purpose of the MSL Area Temperature isolation function is to provide timely detection and isolation of small MSL leaks while maintaining sufficient margin above normal operating temperatures to avoid spurious isolation. The MSL Area Temperature instrumentation is part of the MSIV Group 1 isolation logic and isolates the normally open MSIVs and the normally closed MSL drain valves.

The MST Temperature instrumentation and logic is not required to mitigate any design basis event and credit for this isolation instrumentation is not taken in any transient or accident analysis in Updated Final Safety Analysis Report (UFSAR) Chapter 15. Bounding analyses are performed for large breaks, such as MSL breaks that solely credit the automatic MSL high flow isolation. The MST Temperature isolation and reactor vessel low level and low steam pressure isolations provide a diverse isolation function to the credited MSL high flow isolation. This function does not require an automatic isolation of the MSLs on MST Area high temperature to assure plant safety. Given the purpose of the function, the consequences of an automatic reactor scram due to closure of the MSIVs is unwarranted.

As an alternative, the proposed TS 3.7.10 will ensure that an MSL pressure boundary leak in the MST will be promptly detected, and appropriate actions will be taken. Operators would typically verify temperature from a recorder in the control room, which displays data from four temperature elements in the outboard MSIV room/steam tunnel. The multiplicity of temperature elements and their dispersed arrangement provide confidence that a significant break would be identified on the recorder.

The proposed LCO 3.7.10 requires that the MSL Area maximum temperature be less than or equal to the limits specified in Table 3.7.10-1. The leak detection isolation function is not required to satisfy any design basis event.

The Applicability of LCO 3.7.10 is MODES 1, 2, and 3. In MODES 1, 2, and 3, a Design Basis Accident (DBA) could result in the release of radioactive material into the MST if there is a leak in the MSLs. In MODES 4 and 5, the probability and consequences of a DBA with fission product release into the MST are reduced because of the pressure and temperature limitations in these conditions. Therefore, maintaining MST temperature within limits is not required in MODE 4 or 5. The proposed Applicability is the same as the current Functions 1.e, 1.f, and 1.g.

The proposed SR 3.7.10.1 requires verification that MSL Area maximum temperature be less than or equal to the limits specified in Table 3.7.10-1. The Frequency is controlled under the SFCP, and the initial Frequency will be every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. As stated in SR 3.0.1, SRs must be met between performances of the Surveillance. If the MSL Area maximum temperature exceeds the limits specified in Table 3.7.10-1, operators will be alerted to take action.

The TS 3.7.10 Actions apply if any MSL Area temperature in Table 3.7.10-1 is exceeded. It requires immediate action to determine if there is leakage from the MSL pressure boundary.

MSL Area temperature may be elevated due to reasons other than an MSL pressure boundary leak, such as hot weather, reduced turbine building ventilation airflow or area cooling, and faulty temperature detectors. Verification will determine whether the elevated temperature is due to leakage from the MSL pressure boundary or another reason. Operations personnel are trained to perform the actions required to verify if leakage exists from the MSL pressure boundary, and no additional training or new operator actions will be required to perform the actions of TS 3.7.10.

Quad Cities Nuclear Power Station, Units 1 & 2 f-Evaluation of Proposed Changes Page 3 of 7 If the elevated temperature is determined to not be due to leakage from the MSL pressure boundary and while MSL Area maximum temperature exceeds the limits specified in Table 3.7.10-1, the Actions require verification every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that there is no leakage from the MSL pressure boundary. During Normal power operation, the monitored MST area has elevated radiation levels and adverse environmental conditions. The 12-hour Completion Time balances the small likelihood of a MSL pressure boundary leak occurring since the last verification against the risks of exposing workers to the radiological and environmental conditions to perform the verification.

If leakage from the MSL pressure boundary is detected or if the periodic verification is not performed, the actions require a plant shutdown. The plant must be brought to MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The proposed times are consistent with the requirements of similar specifications and are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

The following TS 3.3.6.1 functions will continue to provide automatic MSL isolation:

Reactor Vessel Water level - Low, Low, Low - Level 1 Main Steam Line Pressure - Low Main Steam Line Flow - High Condenser Vacuum - Low Pursuant to 10 CFR 50.49, Constellation Energy implements an Environmental Qualification (EQ) program under procedure CC-AA-203. EQ concerns will be managed under that EQ procedure in conjunction with the Corrective Action Program (CAP). Procedure OP-AA-108-115 also requires Operational Evaluation (OpEval) for EQ upon discovery of a condition that affects compliance with 10 CFR 50.49. Such an OpEval must show that subsequent failure of the equipment, if under accident conditions, will not result in a consequential failure (i.e. loss of specified safety function). As an enhancement, Quad Cities is also modifying procedure QOS 0005-01, Operations Department Weekly Summary of Daily Surveillance, to include specific direction to perform an evaluation if EQ parameters are exceeded. Additionally, if elevated temperatures within the Main Steam Line Tunnel area reach the condition for entry into the new proposed MSL Area Temperature LCO, Constellation procedure PI-AA-120 also requires entry of the condition into CAP. Pursuant to PI-AA-120, unplanned LCO entry in the condition of applicability for failure to meet TS surveillance acceptance criteria shall result in an evaluation which considers equipment performance and impacts. Therefore, impacts to EQ will be identified and managed per EQ procedures and CAP. No new EQ zones will be created as a result of the proposed change.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria The following applicable regulations and regulatory requirements were reviewed in the development of this submittal:

10 CFR 50.36: (1) installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary; (2) a process variable, design feature, or operating restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; (3) a structure, system, or component that is part of the primary success path and which functions or

Quad Cities Nuclear Power Station, Units 1 & 2 f-Evaluation of Proposed Changes Page 4 of 7 actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; and (4) a structure, system, or component which operating experience or probabilistic risk assessment (PRA) has shown to be significant to public health and safety. As a result, TS requirements which satisfy any of the criteria in 10 CFR 50.36 must be retained in the TS.

MSL pressure boundary leakage in the MSL Area is monitored to protect the assumptions of the accident dose analysis. Therefore, the requirement to monitor MSL Area maximum temperatures is treated as an operating restriction that is an initial condition of a DBA or transient analysis that either assumes the failure of, or presents a challenge to, the integrity of a fission product barrier and is maintained in the TS per Criterion 2. Revising the requirement from an automatic isolation to manual detection and shutdown does not affect the ability to satisfy Criterion 2.

10 CFR Part 50 Appendix A General Design Criteria (GDC) 30: Components which are part of the Reactor Coolant Pressure Boundary (RCPB) shall be designed, fabricated, erected, and tested to the highest quality standards practical. Means shall be provided for detecting and, to the extent practical, identifying the location of the source of reactor coolant leakage.

Means are provided for detecting reactor coolant leakage. The leak detection system consists of sensors and instruments to detect, annunciate, and, in some cases, isolate the RCPB from potential hazardous leaks before predetermined limits are exceeded. As described in UFSAR Section 5.2.5, small leaks are detected by temperature and pressure changes, increased frequency of sump pump operation, and measurement of airborne radioactivity in the primary containment atmosphere. In addition to these means of detection, large leaks are detected by flow rates in process lines and changes in reactor water level. The allowable leakage rates are based on the predicted and experimentally determined behavior of cracks in pipes, the ability to make up coolant system leakage, the normally expected background leakage due to equipment design, and the detection capability of the various sensors and instruments. The total leakage rate limit is established so that, in the absence of normal AC power concurrent with a loss of feedwater supply, makeup capabilities are provided by the Reactor Core Isolation Cooling (RCIC) system. While the leak detection system provides protection from small leaks, the Emergency Core Cooling System (ECCS) network provides protection for the complete range of discharges from ruptured pipes. Thus, protection is provided for the full spectrum of possible discharges. The RCPB and the leak detection system meet the intent of the requirements of GDC 30.

10 CFR Part 50 Appendix A GDC 54: Piping systems penetrating primary reactor containment shall be provided with leak detection, isolation, and containment having redundancy, reliability, and performance capabilities which reflect the importance to safety of isolating these piping systems.

The QCNPS design incorporates various and diverse leak detection and containment isolation features consistent with the requirements of GDC 54. It is proposed that the Main Steam Tunnel Temperature - High function be removed from the TS for containment isolation instrumentation. Appropriate automatic isolations for MSIVs are still retained consistent with GDC 54 by other diverse leakage detection features.

Quad Cities Nuclear Power Station, Units 1 & 2 f-Evaluation of Proposed Changes Page 5 of 7 4.2 Precedents By letter dated October 13, 2021, Southern Nuclear Operating Company (SNC) submitted a license amendment request for Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2 (Hatch) titled, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21286A595). The amendment was approved on May 20, 2022 (ADAMS Accession No. ML22101A094).

Following the approval of the Hatch amendment, on June 13, 2024, Limerick Generating Station submitted "License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9" (ADAMS Accession No. ML24165A264). The amendment was approved on July 29, 2024 (ADAMS Accession No. ML24204A071).

The Hatch "Turbine Building Area Temperature - High," Trip Function served the same purpose as the LGS "Turbine Enclosure Main Steam Line Tunnel Temperature," Trip Function. Both Trip Functions actuated the MSIVs on high temperature indications around the MSL. Both functions were intended to automatically shut down the plant on small indications of leakage on the MSLs.

In both cases, actuation of the function would cause a complicated reactor scram.

QCNPSs "Main Steam Tunnel Area Temperature - High" function also serves the same purpose to isolate the MSIVs automatically upon detection of small leaks on the MSLs.

4.3 No Significant Hazards Consideration In accordance with 10 CFR 50.90, "Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), is submitting requests for amendments to the Technical Specifications (TS) for Clinton Power Station (CPS); Dresden Nuclear Power Station (DNPS), Units 2 and 3; LaSalle County Station (LSCS), Units 1 and 2; Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2; and Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.

The proposed change revises TS Limiting Condition for Operation (LCO) 3.3.6.1, Table 3.3.6.1-1 by deleting Trip Function 1.e, "Main Steam Line Tunnel Temperature - High," and inserting the word "Deleted" in Table 3.3.6.1-1 for the deleted Trip Function. Deletion of Function 1.e does not require modification to existing Surveillance Requirements (SRs).

In addition, the proposed change adds a new TS LCO 3.7.10, "Main Steam Line (MSL) Area Temperature." The new LCO 3.7.10 requires the MSL area maximum temperatures be maintained less than or equal to the limits as specified in new Table 3.7.10-1. The specification is applicable in MODES 1, 2, and 3, which is the same as the existing Trip Functions 1.e in LCO 3.3.6.1. The proposed change also adds a new corresponding SR 3.7.10.1 which requires verification that the MSL area temperatures are maintained in accordance with Table 3.7.10-1 on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In the proposed new TS, if any MSL area maximum temperature exceeds the limits specified in Table 3.7.10-1, immediate action is required to verify there is no leakage from the MSL pressure boundary, and periodic verification is required every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter. If at any time it cannot be verified that there is no leakage from the MSL pressure boundary or if the periodic verification is not performed, the plant must be in MODE 3 (Hot Shutdown) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and MODE 4 (Cold Shutdown) within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The existing leak detection instrumentation will be modified to remove the automatic MSL Isolation Trip Function; all other functions will remain unchanged. CEG has evaluated the

Quad Cities Nuclear Power Station, Units 1 & 2 f-Evaluation of Proposed Changes Page 6 of 7 proposed changes, using the criteria in 10 CFR 50.92, "Issuance of amendment," and has determined that the proposed changes do not involve a significant hazards consideration. The following information is provided to support a finding of no significant hazards consideration.

1. Do the proposed changes involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed changes do not alter any of the previously evaluated accidents in the Updated Final Safety Analysis Report (UFSAR). The proposed changes do not affect any of the initiators of previously evaluated accidents in a manner that would increase the likelihood of the event. The proposed change also eliminates the automatic Main Steam Isolation Valve (MSIV) isolation function associated with MSL Area high temperature from the requirements of the Technical Specifications (TS) and creates TS requirements for MSL Area temperature monitoring in a new TS 3.7.10.

Automatic isolation of the MSIVs on MSL Area high temperature is not an initiator of any accident previously evaluated. A manual plant shutdown initiated due to MSL leakage in the Main Steam Tunnel (MST) or Main Steam Tunnel Lead Enclosure (MSTLE) is not an initiator of any accident previously evaluated. There is no credit taken in any licensing basis analysis for MSIV closure on MSL Area high temperature, and there are no calculations that credit the subject isolation function as a mitigative feature.

As a result, the likelihood of malfunction of an SSC is not increased. The capability and operation of the mitigation systems are not affected by the proposed changes. Thus, the mitigating systems will continue to be initiated and mitigate the consequences of an accident as assumed in the analysis of accidents previously evaluated.

Therefore, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Do the proposed changes create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No The proposed changes will not introduce any new operating modes, safety-related equipment lineups, accident scenarios, system interactions, or failure modes that would create a new or different type of accident. Failure of the system will have the same effect as the present design.

The proposed change eliminates the automatic MSIV isolation function associated with MSL Area high temperatures from the requirements of the TS and creates TS requirements for MSL Area temperature monitoring in a new LCO. Eliminating the automatic isolation of the MSIVs will not create a new or different kind of accident from those previously evaluated as a Main Steam Line Break (MSLB) has been evaluated.

Elimination of the automatic isolation function will not create a new failure mechanism as a plant shutdown continues to be required if an MSL leak is detected.

The proposed change from an MSIV isolation and subsequent scram to a manual shutdown will not create any credible new failure mechanisms, malfunctions, or accident initiators not considered in the design and licensing bases. The unlikely failure to manually detect an MSL leak and shutdown the plant and that failure leading to a MSLB has already been evaluated and is not a new type of accident.

Quad Cities Nuclear Power Station, Units 1 & 2 f-Evaluation of Proposed Changes Page 7 of 7 Therefore, the proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Do the proposed changes involve a significant reduction in a margin of safety?

Response: No The proposed changes do not affect the accident source term, containment isolation, or radiological release assumptions used in evaluating the radiological consequences of any accident previously evaluated and are consistent with safety analysis assumptions and resultant consequences. The proposed changes do not impact reactor operating parameters or the functional requirements of the affected instrumentation systems. The remaining Functions in Table 3.3.6.1-1 will continue to provide protective system actuations. All design basis events, and the reliance on the protective system actuations will remain unchanged. No controlling numerical values for parameters established in the UFSAR or the license or Safety Limits are affected by the proposed changes.

Therefore, the proposed changes do not involve a significant reduction in a margin of safety.

Based on the above evaluation, CEG concludes that the proposed amendments present no significant hazards consideration under the standards set forth in 10 CFR 50.92, paragraph (c), and accordingly, a finding of "no significant hazards consideration" is justified.

4.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or the health and safety of the public.

5.0 ENVIRONMENTAL CONSIDERATION

CEG has determined that the proposed changes would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed changes do not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed changes meet the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, in accordance with 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed changes.

6.0 REFERENCES

1.

Edwin I. Hatch Nuclear Plant Unit Nos. 1 and 2, "Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature" May 20, 2022 (ADAMS Accession No. ML22101A094).

2.

Limerick Generating Station License Amendment Request for Proposed Changes to the Technical Specification Isolation Actuation Instrumentation Tables and New Turbine Enclosure Main Steam Line Tunnel Temperature TS 3/4.7.9, July 29, 2024 (ADAMS Accession No. ML24204A071).