ML20329A341

TSTF-576 Example Scenarios for 12/7/2020 Meeting

ML20329A341
Person / Time
Site:	Technical Specifications Task Force
Issue date:	11/24/2020
From:	BWR Owners Group, Technical Specifications Task Force
To:	Office of Nuclear Reactor Regulation
Honcharik M, NRR/DSS, 301-415-1774
References
TSTF-576
Download: ML20329A341 (11)

Text

TSTF-576 Example Scenarios Slide 2 TSTF-576, Rev. 1 - Methodology Page 10: Page 11:

1 Under the proposed SR, the results of the Inservice Testing Program individual valve testing will be 3 The previous cycle RLA reevaluation may result in one of the following outcomes:

reviewed to verify that the collective performance of the S/RVs will ensure Safety Limit 2.1.2 is protected. If all of the required S/RVs actuate within the assumed tolerance, the SR is met. i. If the previous cycle RLA reevaluation demonstrates that the calculated overpressure is less 3.i than or equal to the RLA calculated peak overpressure for the limiting event (i.e., the RLA If the as-found individual S/RV performance is not within the inputs and assumptions of the results were bounding), then the SR was met and the OPS was operable during the previous previous cycle RLA, the previous cycle overpressure RLA is reevaluated using revised inputs based cycle. It can be assumed that the current cycle RLA inputs and assumptions contain adequate 2 on the as-found test results and the NRC-approved methodology for the licensee. The purpose of the evaluation is to determine if the RLA of the previous cycle bounded the actual plant conservatism to account for the as-found S/RV performance. No further action is required.

performance and the SR was met. This reevaluation may be performed by the licensee or a vendor. 3.iiii. If the previous cycle RLA reevaluation does not demonstrates that the calculated overpressure The evaluation is performed using the measured S/RV lift settings for tested S/RVs and the upper is less than or equal to the RLA calculated peak overpressure for the limiting event (i.e., the limits of the ASME Code testing allowance for any S/RVs that were not tested. Any S/RV that was RLA results are not bounding), the previous cycle overpressure analysis was not consistent required to be tested but that could not be tested, or if the results cannot be determined, is with actual plant performance and the issue will be entered into the Corrective Action assumed to be out-of-service. Program (as required by 10 CFR 50, Appendix B, Criterion XVII, "Corrective Actions,"). The previous cycle performance will be evaluated for reportability under 10 CFR 50.72 and 10 CFR 50.73.

If the previous cycle RLA reevaluation determines the RLA overpressure analysis did not bound 4 actual plant performance, the current cycle overpressure RLA must be reevaluated to determine if the overpressure RLA bounds the actual plant performance.

The current cycle reevaluation will use the licensee's NRC-approved methodology but with inputs revised to consider the results of the as-found S/RV testing. The nature of the changes to the Note: The red paragraph numbers will be 5 inputs will depend on the cause of the as-found failures and the similarities or differences between the previous cycle and the current cycle. An evaluation of the cause of the as-found failures may referenced in the following slides. result in changes to the S/RV tolerances or other assumptions in the reevaluation. If it is determined that the OPS is not operable, the TS Actions require a plant shutdown.

Slide 3 Example Plant Configuration Acronym Definition

• Dome Pressure Safety Limit (SL): <1325psig Cycle N Currently operating plant cycle of operation

• 11 S/RVs, all with same nominal lift setpoints Cycle N-1 Previously operated plant cycle of operation OP Reactor Vessel Over-Pressure

• Standard set of assumed S/RV lift setpoints used RLA Reload Licensing Analysis as input to each cycles RLA: (effectively the Overpressure Analysis of Record, re-performed every reload)

• 10 valves open at +4 psi higher than nominal setpoint SL Safety Limit

• 1 valve fails to open (1 SRVOOS)

S/RV Safety / Relief Valve Legend for scenario slides: SR Surveillance Requirement

- Blue boxes describe the analyses/evaluations that exist prior to performing SR SRVOOS S/RV Out of Service (i.e., the S/RV is assumed to not open)

- Orange boxes describe the available testing to support the SR

- Yellow boxes describe necessary explicit re-analyses, likely performed by the vendor

- Green boxes describe evaluations that can be performed by utility w/o need for explicit vendor re-analysis.

Slide 4 SR Completion Steps:

Paragraph 1 - Satisfied (for N & N-1)

Scenario 1 (SR Met, RLA Valid) (Cycle N-1 test results are all less limiting than the standard set of Cycle N-1 Cycle N assumed S/RV lift setpoints which (operation complete) (currently operating) support the Cycle N-1 and Cycle N RLA: RLA: RLAs, thus both RLAs remains

- Assumes: 10 S/RVs set at +4 psi - Assumes: 10 S/RVs set at +4 psi bounding) and 1 SRVOOS and 1 SRVOOS

- Yields: 1270 psig < 1325 psig SL - Yields: 1290 psig < 1325 psig SL SR MET for Cycle N-1, Cycle N RLA is Valid Cycle N-1 S/RV As-Found Test Results Cycle N Current S/RV Setpoints 10 S/RV test at +2 (not measurable during cycle operation; 1 S/RV tests at +6 (accounted for by RLA 1SRVOOS) all as-left setpoints were within tolerance)

Cycle N SR Evaluation Cycle N SR Between Performance

- The assumed S/RV lift setpoints Evaluation input to the RLA are already more Explicit Evaluation Not Needed conservative than test results (The standard set of assumed S/RV lift

- Thus, the existing Cycle N-1 RLA setpoints which support the Cycle N RLA SL confirmation analysis is bounding have been validated as conservative based directly on the Cycle N-1 test results)

Satisfies SR for Cycle N-1

Slide 5 SR Completion Steps:

Paragraph 1 - Not Satisfied Scenario 2 (SR Met, RLA Valid) (Cycle N-1 test results are NOT all less limiting than the standard set of Cycle N-1 Cycle N assumed S/RV lift setpoints which (operation complete) (currently operating) support the Cycle N-1 RLA, thus the RLA: RLA: Cycle N-1 RLA is not known to be

- Assumes: 10 S/RVs set at +4 psi - Assumes: 10 S/RVs set at +4 psi bounding/conservative) and 1 SRVOOS and 1 SRVOOS Paragraph 2 - Performed

- Yields: 1270 psig < 1325 psig SL - Yields: 1290 psig < 1325 psig SL (explicit re-analysis of Cycle N-1)

Paragraph 3.i - Satisfied (for Cycle N &

Cycle N-1 S/RV As-Found Test Results Cycle N Current S/RV Setpoints N-1) 9 S/RVs test at +2 (not measurable during cycle operation; (re-analysis demonstrates that Cycle 2 S/RVs test at +6 all as-left setpoints were within tolerance) N-1 RLA inputs yield conservative OP results. Thus, the standard set of Cycle N-1 SR Evaluation Cycle N SR Between Performance assumed S/RV lift setpoints are Explicit re-analysis performed Evaluation confirmed conservative, and both Cycle

- Assumes: Cycle N-1 As-Found Explicit Evaluation Not Needed N-1 and N RLAs are validated)

- Yields: 1250 psig (The standard set of assumed S/RV lift

< 1270 psig RLA setpoints which support the Cycle N RLA SR MET for Cycle N-1,

< Safety Limit SR MET have effectively been validated to Cycle N RLA is Valid yield conservative OP results by the Cycle N-1 re-analysis)

Slide 6 SR Completion Steps:

Paragraph 1 - Not Satisfied Scenario 3 (SR Met, RLA Valid) Paragraph 2 - Performed Paragraph 3.i - Not Satisfied (for N)

Cycle N-1 Cycle N (re-analysis did not demonstrates that (operation complete) (currently operating) the standard set of assumed S/RV lift RLA: RLA: setpoints yield bounding RLA results)

- Assumes: 10 S/RVs set at +4 psi - Assumes: 10 S/RVs set at +4 psi Paragraph 3.ii - Satisfied (for N-1) and 1 SRVOOS and 1 SRVOOS (Cycle N-1 re-analysis shows OP with

- Yields: 1270 psig < 1325 psig SL - Yields: 1290 psig < 1325 psig SL as-found setpoints is < SL)

Paragraph 4 - Performed Cycle N-1 S/RV As-Found Test Results Cycle N Current S/RV Setpoints (re-evaluation of Cycle N overpressure 5 S/RVs test at +2 (not measurable during cycle operation; RLA performed) 6 S/RVs test at +6 all as-left setpoints were within tolerance) Paragraph 5 - Satisfied (for N)

(explicit Cycle N RLA re-analysis is not necessary because consideration of the Cycle N-1 as-found Cycle N-1 SR Evaluation Cycle N SR Between Performance 2-stage S/RV test results does not directly indicate Explicit Re-analysis performed Evaluation a concern with the 3-stage S/RVs installed in Cycle

- Assumes: Cycle N-1 As-Found Qualitative Evaluation: N. After qualitative evaluation, the utility

- 2 stage were installed in Cycle N-1, demonstrates that the existing technical basis for

- Yields: 1290 psig their existing Cycle N RLA S/RV setpoint 3 stage are installed in Cycle N

> 1270 psig RLA - Thus Cycle N-1 as-found measurements do not assumptions has not been invalidated)

< Safety Limit SR MET invalidate Cycle N RLA input assumptions SR MET for Cycle N-1, Existing RLA continues to satisfies SR for Cycle N RLA is Valid Cycle N

Slide 7 SR Completion Steps:

Paragraph 1 - Not Satisfied Scenario 4 (SR Met, RLA Valid) Paragraph 2 - Performed Paragraph 3.i - Not Satisfied (for N)

Cycle N-1 Cycle N Paragraph 3.ii - Satisfied (for (operation complete) (currently operating) N-1)

RLA: RLA: Paragraph 4 - Performed

- Assumes: 10 S/RVs set at +4 psi - Assumes: 10 S/RVs set at +4 psi Paragraph 5 - Satisfied (for N)

- Update the standard set of assumed S/RV lift and 1 SRVOOS and 1 SRVOOS setpoints to consider the results of as-found Cycle

- Yields: 1270 psig < 1325 psig SL - Yields: 1290 psig < 1325 psig SL N-1 S/RV testing

- Use the updated set of standard S/RV setpoints as input to an updated Cycle N RLA Cycle N-1 S/RV As-Found Test Results Cycle N Current S/RV Setpoints - The updated Cycle N RLA confirms the SL is met 5 S/RVs test at +2 (not measurable during cycle operation; for Cycle N 6 S/RVs test at +6 all as-left setpoints were within tolerance) SR MET for Cycle N-1, Valid Updated Cycle N RLA Obtained Cycle N-1 SR Evaluation Cycle N SR Between Performance Explicit Re-analysis performed Evaluation Update Standard Set of Assumed S/RV

- Assumes: Cycle N-1 As-Found Requires RLA Update Lift Setpoints used in RLAs *

- Yields: 1290 psig ---------------------------------------------------- Explicit Cycle N-1 Re-analysis of:

> 1270 psig RLA Explicit RLA Update Re-analysis 10 S/RVs set at +5 psi and 1 SRVOOS

- Assumes: 10 S/RVs set at +5 psi and 1 SRVOOS (considers Cycle N-1 as-found setpoints)

< Safety Limit SR MET (updated assumed S/RV setpoints) - Yields: 1310 psig

- Yields: 1310 psig, <1325 psig SL - Thus: Conservative for Generic Use

• This describes a possible technique for updating the standard set of S/RV setpoints to consider the Cycle N-1 test results. Specific approaches to satisfying Paragraph 5 may vary between utilities.

Slide 8 SR Completion Steps:

Paragraph 1 - Not Satisfied Scenario 5 (SR Met, RLA Not Valid) Paragraph 2 - Performed Paragraph 3.i - Not Satisfied (for N)

Cycle N-1 Cycle N Paragraph 3.ii - Satisfied (for N-1)

(operation complete) (currently operating) Paragraph 4 - Performed RLA: RLA: Paragraph 5 - SR Not Met (for N)

- Update the standard set of assumed S/RV lift

- Assumes: 10 S/RVs set at +4 psi - Assumes: 10 S/RVs set at +4 psi setpoints to consider the results of as-found Cycle and 1 SRVOOS and 1 SRVOOS N-1 S/RV testing

- Yields: 1270 psig < 1325 psig SL - Yields: 1290 psig < 1325 psig SL - Use the updated set of standard S/RV setpoints as input to an updated Cycle N RLA

- The updated Cycle N RLA can not confirm that Cycle N-1 S/RV As-Found Test Results Cycle N Current S/RV Setpoints the SR will be met at end of Cycle N 2 S/RVs test at +2 (not measurable during cycle operation; SR MET for Cycle N-1, 9 S/RVs test at +6 all as-left setpoints were within tolerance) Valid Cycle N RLA NOT Obtained Cycle N-1 SR Evaluation Cycle N SR Between Performance Explicit Re-analysis performed Evaluation Update Standard Set of Assumed S/RV

- Assumes: Cycle N-1 As-Found Requires RLA Update Lift Setpoints used in RLAs

- Yields: 1318 psig ---------------------------------------------------- Explicit Cycle N-1 Re-analysis of:

> 1270 psig RLA Explicit RLA Update Re-analysis 11 S/RVs set at +6 psi

- Assumes: 11 S/RVs set at +6 psi (considers Cycle N-1 as-found results)

< Safety Limit SR MET (updated standard set of S/RV setpoints) - Yields: 1320 psig, >1318 psig

- Yields: 1340 psig, >1325 psig SL - Thus: Conservative for Generic Use

Slide 9 SR Completion Steps:

Paragraph 1 - Not Satisfied Scenario 6 (SR NOT Met, RLA Valid) Paragraph 2 - Performed Paragraph 3.i - Not Satisfied (for N)

Cycle N-1 Cycle N Paragraph 3.ii - SR Not Met (for N-1)

(Cycle N-1 re-analysis shows that Cycle N-1 (operation complete) (currently operating) overpressure analysis performed with S/RV RLA: RLA: setpoints at as-found values is > SL)

- Assumes: 10 S/RVs set at +4 psi - Assumes: 10 S/RVs set at +4 psi Paragraph 4 - Performed and 1 SRVOOS and 1 SRVOOS Paragraph 5 - Satisfied (for N)

- Yields: 1280 psig < 1325 psig SL - Yields: 1270 psig < 1325 psig SL (standard setpoint input assumptions revised to consider Cycle N-1 testing, used to produce updated Cycle N RLA, and confirms the SL is Cycle N-1 S/RV As-Found Test Results Cycle N Current S/RV Setpoints satisfied for Cycle N due to a less severe Cycle N 2 S/RVs test at +2 (not measurable during cycle operation; core design) 9 S/RVs test at +6 all as-left setpoints were within tolerance)

SR NOT Met* for Cycle N-1, Valid Updated Cycle N RLA Obtained Cycle N-1 SR Evaluation Cycle N SR Between Performance Explicit Re-analysis performed Evaluation Update Standard Set of Assumed S/RV

- Assumes: Cycle N-1 As-Found Requires RLA Update Lift Setpoints used in RLAs

- Yields: 1328 psig ---------------------------------------------------- Explicit Cycle N-1 Re-analysis of:

> 1280 psig RLA Explicit RLA Update Re-analysis 11 S/RVs set at +6 psi

- Assumes: 11 S/RVs set at +6 psi (considers Cycle N-1 as-found results)

> Safety Limit SR NOT MET (updated standard set of S/RV setpoints) - Yields: 1330 psig, >1328 psig

- Yields: 1320 psig, <1325 psig SL - Thus: Conservative for Generic Use

• More detailed operability assessments for Cycle N-1 may be able to show SR was met. The approach shown here assumes only NRC approved methodologies for cycle OP RLA analyses are utilized.

Slide 10 SR Completion Steps:

Paragraph 1 - Satisfied (for N & N-1)

Scenario 7 (SR Met, RLA Valid) (Cycle N-1 test results are all less limiting than the standard set of Cycle N-1 Cycle N assumed S/RV lift setpoints which (operation complete) (currently operating) support the Cycle N-1 and Cycle N RLA: RLA: RLAs for the purposes of the

- Assumes: 10 S/RVs set at +4 psi - Assumes: 10 S/RVs set at +4 psi overpressure analysis,* thus both and 1 SRVOOS and 1 SRVOOS RLAs remains bounding )

- Yields: 1270 psig < 1325 psig SL - Yields: 1290 psig < 1325 psig SL SR MET for Cycle N-1, Cycle N-1 S/RV As-Found Test Results Cycle N Current S/RV Setpoints Cycle N RLA is Valid 8 S/RV test at +2 (not measurable during cycle operation; 2 S/RVs test at -6 (below +/-3 ASME tolerance) all as-left setpoints were within tolerance)

• However, due to valves opening Cycle N SR Evaluation Cycle N SR Between Performance below allowable set pressure, overall

- The standard set of RLA input Evaluation potential impacts to other analyses assumptions are already more Explicit Evaluation Not Needed due to the valves which opened below conservative than test results for the (theres no concern with Cycle N standard set of the ASME testing tolerance would be purpose of the overpressure analysis, RLA inputs for the purpose of the overpressure evaluated through the utilitys so RLA results are bounding analysis, as theyve been validated as conservative for Cycle N-1) corrective action program

- Satisfies SR for Cycle N-1

Slide 11 SR Completion Steps:

Paragraph 1 - Satisfied (for N & N-1)

Scenario 8 (SR Met, RLA Valid) (The combination of the Cycle N-1 measured test results and assumed Cycle N-1 Cycle N SR Evaluation test results allowed per ASME code (operation complete) are all less limiting than the standard 4 S/RV test at +2 and set of assumed S/RV lift setpoints RLA: 6 S/RV assumed test result at +3

- Assumes: 10 S/RVs set at +4 psi are bounded by which support the Cycle N-1 and Cycle and 1 SRVOOS RLA assumed 10 S/RV at +4 psi N RLAs, thus both RLAs remains

- Yields: 1270 psig < 1325 psig SL bounding) 1 S/RV test at +6 is bounded by Cycle N-1 S/RV As-Found Test Results RLA assumed 1 SRVOOS SR MET for Cycle N-1, (limited-scope valve testing) Cycle N RLA is Valid

Conclusion:

the assumed S/RV lift setpoints 5 of 11 total S/RVs tested:

input to the RLA are already more

- 4 S/RV test at +2 (within ASME tolerance) conservative than test results

- 1 S/RVs test at +6 (above ASME tolerance)

- Thus, the existing Cycle N-1 RLA SL confirmation analysis is bounding ASME code does not require further explicit Satisfies SR for N-1 testing of valves against +/-3 tolerance Cycle N SR Between Performance

- remaining 6 S/RVs assumed test result at +3 Evaluation (top end of ASME tolerance) Explicit Evaluation Not Needed