PLA-8195, Proposed Amendment to Licenses NPF-14 and NPF-22: Standby Liquid Control System Boron Solution Storage Tank Volume (PLA-8195)

Proposed Amendment to Licenses NPF-14 and NPF-22: Standby Liquid Control System Boron Solution Storage Tank Volume (PLA-8195)

ML26026A109
Person / Time
Site:	Susquehanna   (NPF-014, NPF-022)
Issue date:	01/26/2026
From:	Michael Jones Susquehanna
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
PLA-8195
Download: ML26026A109 (0)

Text

Mark Jones Susquehanna Nuclear, LLC Site Vice President 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.1057 Fax 570.542.1504 Mark.Jones@TalenEnergy.com Attn: Document Control Desk 10 CFR 50.90 U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 SUSQUEHANNA STEAM ELECTRIC STATION PROPOSED AMENDMENT TO LICENSES NPF-14 AND NPF-22: STANDBY LIQUID CONTROL SYSTEM BORON SOLUTION STORAGE TANK VOLUME PLA-8195 Docket No. 50-387 and 50-388 Pursuant to 10 CFR 50.90, Susquehanna Nuclear, LLC (Susquehanna), is submitting a request for an amendment to the Technical Specifications (TS) for the Susquehanna Steam Electric Station (SSES), Units 1 and 2, Facility Operating License numbers NPF-14 and NPF-22. The proposed change increases the minimum boron solution storage tank volume requirements of TS Figure 3.1.7-1, "Sodium Pentaborate Solution Volume Versus Concentration Requirements," for the Standby Liquid Control (SLC) System. provides a description and assessment of the proposed changes along with Susquehanna's determination that the proposed changes do not involve a significant hazard consideration. Attachment 2 provides the existing TS pages marked to show the proposed changes. Attachment 3 provides revised (clean) TS pages. Attachment 4 provides the existing TS Bases pages marked up to show the proposed changes and is provided for information only.

Susquehanna requests NRC approval of the proposed changes and issuance of the requested license amendment by January 31, 2027. Once approved, the Unit 1 amendment shall be implemented prior to the startup from the 2028 Unit 1 refueling outage and the Unit 2 amendment shall be implemented prior to the startup from the 2027 refueling outage.

In accordance with 10 CFR 50.91, Susquehanna is providing a copy of this application, with attachments, to the designated Commonwealth of Pennsylvania state official.

Both the Plant Operations Review Committee and the Nuclear Safety Review Board have reviewed the proposed changes.

There are no new or revised regulatory commitments contained in this submittal.

January 26, 2026 TALEN~

ENERGY Document Control Desk PLA-8195 Should you have any questions regarding this submittal, please contact Ms. Melisa Krick, Manager-Nuclear Regulatory Affairs, at (570) 542-1818.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on January 26, 2026.

Mfi!v,~

Attachment:

1. Description and Assessment

2. Marked-Up Technical Specification Pages

3. Revised (Clean) Technical Specification Pages

4. Marked-Up Technical Specification Bases Pages (Provided for Information Only)

Copy:

NRC Region I Mr. R. Wehrmann, NRC Senior Resident Inspector Mr. R. Guzman, NRC Project Manager Mr. M. Shields, PADEP/BRP

to PLA-8195 Description and Assessment

1.

SUMMARY

DESCRIPTION

2.

DETAILED DESCRIPTION 2.1 System Design and Operation 2.2 Current Technical Specifications Requirements 2.3 Reason for the Proposed Change 2.4 Description of the Proposed Change

3.

TECHNICAL EVALUATION

4.

REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Considerations Analysis 4.4 Conclusions

5.

ENVIRONMENTAL CONSIDERATION

6.

REFERENCES to PLA-8195 Page 1 of 8 SUSQUEHANNA ASSESSMENT

1.

Summary Description Pursuant to 10 CFR 50.90, Susquehanna Nuclear, LLC (Susquehanna), is submitting a request for an amendment to the Technical Specifications (TS) for the Susquehanna Steam Electric Station (SSES), Units 1 and 2, Facility Operating License numbers NPF-14 and NPF-22. The proposed change increases the minimum boron solution storage tank volume requirements of TS Figure 3.1.7-1, "Sodium Pentaborate Solution Volume Versus Concentration Requirements," for the Standby Liquid Control (SLC) System.

2.

Detailed Description 2.1 System Design and Operation The SLC System is designed to provide the capability of bringing the reactor, at any time in a fuel cycle, from full power and minimum control rod inventory, which is at the peak of the xenon transient, to a subcritical condition with the reactor in the most reactive, xenon free state without taking credit for control rod movement. The SLC System satisfies the requirements of 10 CFR 50.62, "Requirements for reduction of risk from anticipated transients without scram (ATWS) events for light-water-cooled nuclear power plants."

The SLC System consists of a sodium pentaborate (SPB) solution storage tank, two positive displacement pumps, two explosive valves that are provided in parallel for redundancy, and associated piping and valves used to transfer borated water from the storage tank to the reactor pressure vessel (RPV). The borated solution is discharged near the bottom of the core shroud, where it then mixes with the cooling water rising through the core.

The SLC System is used in the event that enough control rods cannot be inserted to accomplish shutdown and cooldown in the normal manner or if fuel damage occurs following a loss of coolant accident (LOCA). The SLC System injects borated water into the reactor core to add negative reactivity to compensate for all of the various reactivity effects that could occur during plant operations.

The SLC System is also used to maintain suppression pool pH level above 7.0 following a LOCA involving significant fission product releases. Maintaining suppression pool pH levels greater than 7.0 following an accident ensures that iodine will be retained in the suppression pool water as reflected in the LOCA dose analysis.

to PLA-8195 Page 2 of 8 2.2 Current Technical Specifications Requirements To comply with 10 CFR 50.62, SSES uses a SPB solution with boron enriched to 88 atom-percent with boron-10 (B-10) isotope. The current volume versus concentration limits in TS Figure 3.1.7-1 are established to ensure that the SLC System injects a quantity of boron which produces a concentration of 660 parts per million (ppm) equivalent of natural boron in the reactor coolant at 68 °F with normal RPV water level. The current TS Figure 3.1.7-1 was established with issuance of the amendments approving use of SLC single pump operation and use of enriched boron (Reference 1).

2.3 Reason for the Proposed Change To accommodate core reload flexibility, the minimum boron solution storage tank volume requirements are being increased, resulting in an increase of the amount of boron in the vessel post SLC System injection from 660 ppm equivalent of natural boron to 850 ppm. Note the required SLC System boron solution storage tank concentrations remain unchanged. This increase in boron concentration will add significant margin to the SLC shutdown margin (SDM) analysis which will sufficiently bound future advancements in core designs without impacting operation. While recent core designs have shown a reduction in SLC SDM, reloads will require

> 660 ppm to achieve the required design margin.

2.4 Description of the Proposed Change The proposed change increases the minimum boron solution storage tank volume requirements of TS Figure 3.1.7-1. This is accomplished by shifting the left boundary of the acceptable region of TS Figure 3.1.7-1 to the right. The existing minimum volume at a concentration of 10.0 weight percent SPB is increased from 1350 gallons to 1755 gallons. The existing minimum volume at a concentration of 7.0 weight percent SPB is increased from 1965 gallons to 2540 gallons. The increased volumes are conservatively rounded up. No additional TS changes are required to support the increase in boron concentration from 660 ppm to 850 ppm.

The Applicable Safety Analysis section of the TS 3.1.7 Bases currently refers to 660 ppm equivalent of natural boron in the reactor coolant at 68 °F. This is being updated to the new value of 850 ppm. The Unit 1 and Unit 2 TS Bases pages, marked to show this change, are provided for information only.

3.

Technical Evaluation The minimum amount of SPB to inject into the RPV (i.e., left boundary of TS Figure 3.1.7-1) results in an equivalent concentration of natural boron (i.e., concentration used in the SLC SDM calculation) in the reactor coolant based on SPB concentration and B-10 enrichment. The quantity of reactor coolant is based on water, at 68 °F, in the RPV at normal vessel level, the to PLA-8195 Page 3 of 8 recirculation loops, and the Shutdown Cooling portion of the Residual Heat Removal System.

The analysis used to calculate the necessary quantity of SPB to achieve the desired concentration equivalent of natural boron in the reactor coolant includes 25 percent margin. This accounts for imperfect mixing, leakage, and additional water volume found in small piping connected to the RPV.

Increasing the boron concentration of equivalent natural boron to 850 ppm results in an increase in the minimum acceptable SPB solution volume reflected in the revised TS Figure 3.1.7-1.

Since there are no changes to the SPB concentration (i.e., TS Figure 3.1.7-1 weight percent),

SPB B-10 enrichment (i.e., 88 atom-percent) or the reactor coolant volume, the increase in SPB minimum volume is directly proportional to the increase in boron concentration. This is demonstrated below for a SPB concentration of 10.0 weight percent:

=

= 1350 850 660 = 1738.6 1755 The volume is conservatively rounded up.

The proposed change is more restrictive than the current acceptable region in TS Figure 3.1.7-1 and does not allow SLC tank concentration and volume combinations outside the currently approved range. In addition, no SLC System boron solution storage tank modifications are required based on recent surveillances of SLC tank level (SR 3.1.7.1).

4.

Regulatory Evaluation 4.1 Applicable Regulatory Requirements/Criteria The requirements for ATWS are specified in 10 CFR 50.62, which requires, in part, that:

Each boiling water reactor must have a standby liquid control system (SLCS) with the capability of injecting into the reactor pressure vessel a borated water solution at such a flow rate, level of boron concentration and boron-10 isotope enrichment, and accounting for reactor pressure vessel volume, that the resulting reactivity control is at least equivalent to that resulting from injection of 86 gallons per minute of 13 weight percent sodium pentaborate decahydrate solution at the natural boron-10 isotope abundance into a 251-inch inside diameter reactor pressure vessel for a given core design.

to PLA-8195 Page 4 of 8 The current compliance with 10 CFR 50.62 is based on an equivalency equation from NEDE-31096-A (Reference 2), shown below.

86 x 251

x 13 x

19.8 1 where:

Variable Description Value Q

Expected SLC System flow rate.

40 gallons per minute M251/M Mass of water in the RPV and recirculation system at hot rated conditions. Since SSES has a 251-inch diameter RPV, the value of M251/M is equal to one (1).

1 C

Minimum sodium pentaborate solution concentration.

7 weight percent E

Minimum B-10 enrichment 88 atom percent When solved for the above values:

40 86 x 7 13 x 88 19.8 = 1.11 1 None of the variables in this equation (i.e., flow rate, vessel water mass, SPB concentration and B-10 enrichment) are impacted by this change. Therefore, the requirements of 10 CFR 50.62 continue to be satisfied with the same margin established with the approval of Reference 1.

10 CFR 50.67, "Accident source term," in part, sets limits for the radiological consequences of a postulated design-basis accident using an accident source term. The analytical methods described in Regulatory Guide 1.183, "Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors," July 2000, and dose limits defined in 10 CFR 50.67 comprise the design basis for SSES (i.e., Reference 3). The SSES Alternate Source Term analyses credit the use of the SLC injection to maintain a Suppression Pool pH of 7.0 or greater. Maintaining this pH retains the iodine deposited in the Suppression Pool from a design basis LOCA in solution. Therefore, if a design basis LOCA were to occur, the entire contents of the SLC tank are manually injected. The proposed change to increase the minimum boron solution storage tank volume requirements of TS Figure 3.1.7-1 does not adversely impact the ability to maintain the suppression pH at or above 7.0.

4.2 Precedent In Reference 4, the NRC granted approval to Brunswick Steam Electric Plant (BSEP), Units 1 and 2, for an amendment to revise TS Figure 3.1.7-1 to increase the minimum boron solution to PLA-8195 Page 5 of 8 storage tank volume requirements for the SLC System. BSEP is a Boiling Water Reactor 4 design, consistent with SSES, Units 1 and 2. Therefore, the identified precedent is relevant to SSES, Units 1 and 2.

4.3 No Significant Hazards Considerations Analysis In accordance with the requirements of 10 CFR 50.90, Susquehanna Nuclear, LLC (Susquehanna), requests an amendment to the Technical Specifications (TS) for the Susquehanna Steam Electric Station (SSES), Units 1 and 2. The proposed change increases the minimum boron solution storage tank volume requirements of TS Figure 3.1.7-1, "Sodium Pentaborate Solution Volume Versus Concentration Requirements," for the Standby Liquid Control (SLC) System.

Susquehanna has evaluated the proposed amendment against the standards in 10 CFR 50.92 and has determined that the operation of SSES in accordance with the proposed amendment presents no significant hazards. Susquehannas evaluation against each of the criteria in 10 CFR 50.92 follows.

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

Response: No The proposed change does not involve a physical alteration of the plant (i.e., no new or different type of equipment will be installed). The proposed change increases the minimum boron solution storage tank volume requirements included in TS Figure 3.1.7-1. The plant response to design basis accidents does not change. Operation or failure of the SLC System is not assumed to be an initiator of any analyzed event in the Susquehanna Updated Final Safety Analysis Report and cannot cause an accident. The proposed change conforms to NRC regulatory requirements regarding anticipated transients without scram (ATWS) and accident source term (AST).

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

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

Response: No The proposed change increases the minimum boron solution storage tank volume requirements included in TS Figure 3.1.7-1. It does not require any physical modification to to PLA-8195 Page 6 of 8 the plant and it does not alter the design configuration, or method of operation of plant equipment beyond its normal functional capabilities. The proposed change does not reduce or adversely affect the capabilities of any plant structure, system, or component in the performance of their safety function. Also, the response of the plant and the operators following design basis accidents is unaffected by the proposed change.

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

3. Does the proposed change involve a significant reduction in a margin of safety?

Response: No The proposed change increases the minimum boron solution storage tank volume requirements included in TS Figure 3.1.7-1. The proposed changes conform to NRC regulatory requirements regarding ATWS and AST. To accommodate core reload flexibility, the assumed 660 ppm equivalent of natural boron is being increased to 850 ppm, which is accomplished by increasing the minimum boron solution storage tank volume requirements.

This increase in boron concentration will add significant margin to the SLC shutdown margin analysis and will sufficiently bound future advancements in core designs without impacting operation. The proposed change conforms to NRC regulatory requirements regarding ATWS and AST.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above evaluation, Susquehanna concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(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 Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

5.

Environmental Consideration Susquehanna has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined to PLA-8195 Page 7 of 8 in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does 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 amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

to PLA-8195 Page 8 of 8

6.

References

1.

NRC letter to PPL Susquehanna, LLC, Susquehanna Steam Electric Station, Units 1 and 2 - Issuance of Amendment Re: Standby Liquid Control System (TAC Nos. MD1424 and MD1425), dated February 28, 2007 (ADAMS Accession No. ML070590427).

2.

NEDE-31096-A, Anticipated Transients Without SCRAM: Response to NRC ATWS Rule 10 CFR 50.62, dated February 1987 (ADAMS Accession No. ML20235J965).

3.

NRC letter to PPL Susquehanna, LLC, Susquehanna Steam Electric Station Units 1 and 2 - Issuance of Amendment Re: Implementation of Alternate Radiological Source Term (TAC Nos. MC8730 and MC8731), dated January 31, 2007 (ADAMS Accession No. ML070310214).

4.

NRC Letter to Duke Energy Progress, LLC, Brunswick Steam Electric Station, Units 1 and 2 - Issuance of Amendment Nos. 306 and 334 to Review Standby Liquid Control System Boron Solution Storage Tank Volume Technical Specification (EPID L-2021-LLA-0022), dated December 14, 2021 (ADAMS Accession No. ML21281A138).

of PLA-8195 Marked-Up Technical Specification Pages Revised Technical Specification Pages Unit 1 TS Pages 3.1-23 Unit 2 TS Pages 3.1-23

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of PLA-8195 Revised (Clean) Technical Specification Pages Revised Technical Specification Pages Unit 1 TS Pages 3.1-23 Unit 2 TS Pages 3.1-23

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6 7

8 9

10 11 12 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 Solution Concentration (Weight - percent)

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10 11 12 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 Solution Concentration (Weight - percent)

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of PLA-8195 Marked-Up Technical Specification Bases Pages (Provided for Information Only)

Revised Technical Specification Bases Pages Unit 1 TS Bases Pages 3.1-39, 41 Unit 2 TS Bases Pages 3.1-39, 41

SLC System B 3.1.7 SUSQUEHANNA - UNIT 1 3.1-39 B 3.1 REACTIVITY CONTROL SYSTEMS B 3.1.7 Standby Liquid Control (SLC) System BASES BACKGROUND The SLC System is designed to provide the capability of bringing the reactor, at any time in a fuel cycle, from full power and minimum control rod inventory to a subcritical condition with the reactor in the most reactive, xenon free state without taking credit for control rod movement.

Additionally, the SLC System is designed to provide sufficient buffering agent to maintain the suppression pool pH at or above 7.0 following a DBA LOCA involving fuel damage. Maintaining the suppression pool pH at or above 7.0 will mitigate the re-evolution of iodine from the suppression pool water following a DBA LOCA. The SLC System satisfies the requirements of 10 CFR 50.62 (Ref. 1) for anticipated transient without scram.

The SLC System consists of a sodium pentaborate solution storage tank, two positive displacement pumps, two explosive valves that are provided in parallel for redundancy, and associated piping and valves used to transfer borated water from the storage tank to the reactor pressure vessel (RPV).

The borated solution is discharged near the bottom of the core shroud, where it then mixes with the cooling water rising through the core. A smaller tank containing demineralized water is provided for testing purposes.

APPLICABLE SAFETY ANALYSES The SLC System is manually initiated from the main control room, as directed by the emergency operating procedures, if the operator believes the reactor cannot be shut down, or kept shut down, with the control rods or if fuel damage occurs post-LOCA. The SLC System is used in the event that enough control rods cannot be inserted to accomplish shutdown and cooldown in the normal manner or if fuel damage occurs post-LOCA. The SLC System injects borated water into the reactor core to add negative reactivity to compensate for all of the various reactivity effects that could occur during plant operations. To meet this objective, it is necessary to inject a quantity of enriched sodium pentaborate, which produces a concentration equivalent to 850660 ppm of natural boron, in the reactor coolant at 68F. To allow for potential leakage and imperfect mixing in the reactor system, an amount of boron equal to 25% of the amount cited above is added (Ref. 2). The volume versus concentration limits in Figure 3.1.7-1 and the temperature versus concentration limits in Figure 3.1.7-2 are calculated such that the required concentration is achieved accounting for dilution in the RPV with normal water level and including the water volume in the residual heat removal shutdown cooling piping and in the

SLC System B 3.1.7 SUSQUEHANNA - UNIT 1 3.1-41 BASES APPLICABILITY (continued)

A DBA LOCA that results in the release of radioactive material is possible in MODES 1, 2 and 3; therefore, capability to buffer the suppression pool pH is required. In MODES 4 and 5, a DBA LOCA with radioactive release need not be postulated.

ACTIONS A.1 If the boron solution concentration is not within the limits in Figure 3.1.7-1, the operability of both SLC subsystems is impacted and the concentration must be restored to within limits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The allowed Completion Time of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is considered acceptable given the low probability of an event occurring concurrent with the failure of the control rods to shut down the reactor.

If the boron solution concentration is >12 weight-percent with the tank volume 17551350 gallons, both SLC subsystems are operable as long as the temperature for the boron solution concentration is within the acceptable region of Figure 3.1.7-2. If the temperature requirements are not met, operability of both SLC subsystems is impacted and the concentration or solution temperature must be restored within limits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

B.1 If one SLC subsystem is inoperable for reasons other than Condition A, the inoperable subsystem must be restored to OPERABLE status within 7 days or in accordance with the Risk Informed Completion Time Program. In this condition, the remaining OPERABLE subsystem is adequate to perform the shutdown function and provide adequate buffering agent to the suppression pool. However, the overall reliability is reduced because a single failure in the remaining OPERABLE subsystem could result in reduced SLC System shutdown capability. The 7 day Completion Time is based on the availability of an OPERABLE subsystem capable of performing the intended SLC System functions and the low probability of an event occurring requiring SLC injection.

C.1 If both SLC subsystems are inoperable for reasons other than Condition A, at least one subsystem must be restored to OPERABLE status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The allowed Completion Time of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is considered acceptable given the low probability of an event occurring requiring SLC injection.

SLC System B 3.1.7 SUSQUEHANNA - UNIT 2 3.1-39 B 3.1 REACTIVITY CONTROL SYSTEMS B 3.1.7 Standby Liquid Control (SLC) System BASES BACKGROUND The SLC System is designed to provide the capability of bringing the reactor, at any time in a fuel cycle, from full power and minimum control rod inventory to a subcritical condition with the reactor in the most reactive, xenon free state without taking credit for control rod movement.

Additionally, the SLC System is designed to provide sufficient buffering agent to maintain the suppression pool pH at or above 7.0 following a DBA LOCA involving fuel damage. Maintaining the suppression pool pH at or above 7.0 will mitigate the re-evolution of iodine from the suppression pool water following a DBA LOCA. The SLC System satisfies the requirements of 10 CFR 50.62 (Ref. 1) for anticipated transient without scram.

The SLC System consists of a sodium pentaborate solution storage tank, two positive displacement pumps, two explosive valves that are provided in parallel for redundancy, and associated piping and valves used to transfer borated water from the storage tank to the reactor pressure vessel (RPV).

The borated solution is discharged near the bottom of the core shroud, where it then mixes with the cooling water rising through the core. A smaller tank containing demineralized water is provided for testing purposes.

APPLICABLE SAFETY ANALYSES The SLC System is manually initiated from the main control room, as directed by the emergency operating procedures, if the operator believes the reactor cannot be shut down, or kept shut down, with the control rods or if fuel damage occurs post-LOCA. The SLC System is used in the event that enough control rods cannot be inserted to accomplish shutdown and cooldown in the normal manner or if fuel damage occurs post-LOCA. The SLC System injects borated water into the reactor core to add negative reactivity to compensate for all of the various reactivity effects that could occur during plant operations. To meet this objective, it is necessary to inject a quantity of enriched sodium pentaborate, which produces a concentration equivalent to 850660 ppm of natural boron, in the reactor coolant at 68F. To allow for potential leakage and imperfect mixing in the reactor system, an amount of boron equal to 25% of the amount cited above is added (Ref. 2). The volume versus concentration limits in Figure 3.1.7-1 and the temperature versus concentration limits in Figure 3.1.7-2 are calculated such that the required concentration is achieved accounting for dilution in the RPV with normal water level and including the water volume in the residual heat removal shutdown cooling piping and in the

SLC System B 3.1.7 SUSQUEHANNA - UNIT 2 3.1-41 BASES APPLICABILITY (continued)

A DBA LOCA that results in the release of radioactive material is possible in MODES 1, 2 and 3; therefore, capability to buffer the suppression pool pH is required. In MODES 4 and 5, a DBA LOCA with a radioactive release need not be postulated.

ACTIONS A.1 If the boron solution concentration is not within the limits in Figure 3.1.7-1, the operability of both SLC subsystems is impacted and the concentration must be restored to within limits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The allowed Completion Time of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is considered acceptable given the low probability of an event occurring concurrent with the failure of the control rods to shut down the reactor.

If the boron solution concentration is > 12 weight-percent with the tank volume 17551350 gallons, both SLC subsystems are operable as long as the temperature for the boron solution concentration is within the acceptable region of Figure 3.1.7-2. If the temperature requirements are not met, operability of both SLC subsystems is impacted and the concentration or solution temperature must be restored within limits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

B.1 If one SLC subsystem is inoperable for reasons other than Condition A, the inoperable subsystem must be restored to OPERABLE status within 7 days or in accordance with the Risk Informed Completion Time Program. In this condition, the remaining OPERABLE subsystem is adequate to perform the shutdown function and provide adequate buffering agent to the suppression pool. However, the overall reliability is reduced because a single failure in the remaining OPERABLE subsystem could result in reduced SLC System shutdown capability. The 7 day Completion Time is based on the availability of an OPERABLE subsystem capable of performing the intended SLC System functions and the low probability of an event occurring requiring SLC injection.

C.1 If both SLC subsystems are inoperable for reasons other than Condition A, at least one subsystem must be restored to OPERABLE status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The allowed Completion Time of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is considered acceptable given the low probability of an event occurring requiring SLC injection.