ML14349A707

Draft Request for Additional Information

ML14349A707
Person / Time
Site:	Peach Bottom
Issue date:	12/12/2014
From:	Richard Ennis Plant Licensing Branch 1
To:	Meena Khanna Plant Licensing Branch 1
Rick Ennis, NRR/DORL 415-1420
References
TAC MF4757, TAC MF4758
Download: ML14349A707 (7)

Text

MEMORANDUM TO: Meena K. Khanna, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation _ C' FROM: Richard B. Ennis, Senior Project Manager Plant Licensing Branch 1-2

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Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

SUBJECT:

PEACH BOTTOM ATOMIC POWER STATION, UNITS 2 AND 3, DRAFT REQUEST FOR ADDITIONAL INFORMATION (TAC NOS.

MF4757 AND MF4758)

The attached draft request for additional information (RAI) was transmitted on December 12, 2014, to Mr. Richard Gropp of Exelon Generation Company, LLC (Exelon, the licensee). This information was transmitted to facilitate an upcoming conference call in order to clarify the licensee's amendment request for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, dated September 3, 2014. The proposed amendment would revise the Technical Specifications (TSs) to eliminate the Main Steam Line Radiation Monitor (MSLRM) from initiating: (1) a Reactor Protection System (RPS) automatic reactor scram; and (2) a Primary Containment Isolation System (PC IS) isolation including automatic closure of the Main Steam Line Isolation Valves (MSIVs), Main Steam Line (MSL) drain valves, MSL sample line valves, Residual Heat Removal (RHR) system sample line valves, and Reactor Recirculation loop sample line valves.

Existing requirements for the Mechanical Vacuum Pump (MVP) would be retained in the Technical Requirements Manual (TRM).

The draft RAI was sent to Exelon to ensure that the questions are understandable, the regulatory basis for the questions is clear, and to determine if the information was previously docketed. This memorandum and the attachment do not convey or represent an NRC staff position regarding the licensee's request.

Docket Nos. 50-277 and 50-278

Attachment:

Draft RAI

DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED LICENSE AMENDMENT ELIMINATE MAIN STEAM LINE RADIATION MONITOR TRIP AND ISOLATION FUNCTION EXELON GENERATION COMPANY, LLC PEACH BOTTOM ATOMIC POWER STATION- UNITS 2 AND 3 DOCKET NOS. 50-277 AND 50-278 By letter dated September 3, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14247A522), Exelon Generation Company, LLC (Exelon, the licensee) submitted a license amendment request for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3. The proposed amendment would revise the Technical Specifications (TSs) to eliminate the Main Steam Line Radiation Monitor (MSLRM) from initiating: (1) a Reactor Protection System (RPS) automatic reactor scram; and (2) a Primary Containment Isolation System (PCIS) isolation including automatic closure of the Main Steam Line Isolation Valves (MSIVs), Main Steam Line (MSL) drain valves, MSL sample line valves, Residual Heat Removal (RHR) system sample line valves, and Reactor Recirculation loop sample line valves.

Existing requirements for the Mechanical Vacuum Pump (MVP) would be retained in the Technical Requirements Manual (TRM).

The Nuclear Regulatory Commission (NRC) staff has reviewed the information the licensee provided that supports the proposed amendment and would like to discuss the following issues to clarify the submittal.

PRA and Human Performance Branch (APHB)

Reviewer: Brian Green APHB-RAI-1 Please identify any operator manual actions that will be added, deleted, or changed to support the proposed license amendment. Include any changes to the time available or the sequence of actions.

APHB-RAI-2 Has an operating experience review (OER) been done, including plant-specific condition reports, Licensee Event Reports, INPO reports, and other relevant sources? Did the OER identify any plants that completed similar changes (i.e., automatic closure of the MSL drain valves, MSL sample lines, RHR system sample lines, and Reactor Recirculation loop sample lines) that go beyond the scope of General Electric (GE) topical report NED0-31400A, "Safety Evaluation for Eliminating the Boiling Water Reactor Main Steam Line Isolation Valve Closure Functions and Scram Function of the Main Steam Line Radiation Monitor"? If so, which plants?

Attachment

APHB-RAI-3 Do the planned changes described in the license amendment request (LAR) trigger changes to the plant Functional Requirement Analysis, Function Allocation, or Task Analysis? If so, please describe the changes.

APHB-RAI-4 Do the changes described in the LAR cause there to be changes to risk-important human actions or to any actions necessary to place the reactor in a safe condition? Are there changes to the consequences of manual action errors? Are there any additional actions required as a consequence of this proposed modification?

APHB-RAI-5 Please describe any changes to operating procedures, abnormal procedures, and/or emergency operating procedures needed to support the proposed license amendment.

APHB-RAI-6 Please describe any changes to operator training, qualifications, and the simulator needed to support the proposed license amendment.

APHB-RAI-7 Describe the process used to verify and validate the ability of your operators to accomplish the tasks required for the proposed amendment. In lieu of a description, you may provide the relevant administrative procedure(s) that were used for verification and validation. Did the validation include a representative sample of operators, and was it done with TS minimum staffing and nominal staffing?

APHB-RAI-8 What are the credible operator errors that can occur during the manual trip/containment isolation actions? Please provide evidence that recovery from errors is possible within the time available for relevant accident scenarios.

APHB-RAI-9 Are the manual actions that replace the automatic actions being removed part of a time-critical action monitoring program? If not, by what controlled process will the credited actions be protected from inadvertent changes due to design changes and procedure changes?

Radiation Protection and Consequence Branch (ARCB)

Reviewer: Kristy Bucholtz ARCB-RAI-1 On page 13 of Attachment 1 to the application dated September 3, 2014, it states:

In order to assess the radiological impact of a scenario where a CRDA [control rod drop accident] occurred coincidentally with an open sample line, it was conservatively assumed that the largest sample line is "open" for one hour prior to being isolated by remote-manual action taken by licensed MCR [main control room] operators.

Calculation number PM-1168 (Attachment 5 to the application) assumes a sample purge rate of 500 milliliters per minute or 500 cubic centimeters per minute, but does not provide the maximum flow rate possible for each of the sample lines. Provide the maximum flow rate possible from the MSL sample line, RHR sample line and the Reactor Recirculation loop sample line. In addition, discuss any included safety margin included in the chosen sample purge rate of 500 milliliters per minute or 500 cubic centimeters per minute.

ARCB-RAI-2 Explain if it is possible to have all three-sample lines open at the same time. If it is possible to have all three-sample lines open at the same time, explain how this is accounted for in calculation PM-1168.

ARCB-RAI-3 Regulatory Guide (RG) 1.183, Section 4.4, "Acceptance Criteria," states that:

The acceptance criteria for the various NUREG-0737 (Ref. 2) items generally reference General Design Criteria 19 (GDC 19) from Appendix A to 10 CFR Part 50 or specify criteria derived from GDC-19. These criteria are generally specified in terms of whole body dose, or its equivalent to any body organ. For facilities applying for, or having received, approval for the use of an AST

[alternative source term], the applicable criteria should be updated for consistency with the TEDE [total effective dose equivalent] criterion in 10 CFR 50.67(b)(2)(iii).

In evaluating the submittal, the NRC staff could not determine if RG 1.183, Acceptance Criteria 4.4 had been assessed and met for PBAPS. Please provide additional information describing what is meant by remote-manual action to isolate a sample line and discuss whether or not the operator action of isolating the sample line would meet the requirements of NUREG-0737, "Clarification of TMI Action Plan Requirements," Task Action 11.8.2. This NUREG-0737 requirement ensures these actions can be completed without exceeding the acceptance criteria (typically contained in GDC-19) for mission doses.

ARCB-RAI-4 Calculation number PM-1 057 (Attachment 4 to the application), Section 7.1 provides the method for calculating the post-CRDA composite activity release fractions to the reactor coolant. The method utilizes the following release fractions:

Gap Release Melt Release Group Fraction Fraction Noble Gases 10% 100%

Iodine 10% 50%

Alkali metals 12% 25%

These fractions are used to determine a combined release fraction for the noble gases, iodines, and alkali metals. The release fraction was determined to be 0.12 for iodine, 0.145 for noble gases, and 0.1265 for the alkali metals and these fractions are then used in Table 2 Column B to calculate the total gap activity released to the reactor coolant (Column D). The total gap activity released to the reactor coolant calculated in Table 2 column D states that it was calculated by multiplying together columns A, B and C.

However, Column C is the fraction of gap activity released to reactor coolant, which was already accounted for in the calculation in Section 7.1 (Column B). Please, explain why the fraction of gap activity released to reactor coolant (Column C) was used to calculate the total gap activity released to the reactor coolant (Column D) considering it was included in the combined release fraction (shown in Column B) from Section 7.1.

ARCB-RAI-5 On page 39 of 102 in Attachment 13.1 and page 52 of 102 in Attachment 13.2 of calculation PM-1 057 ,pathway 1 (reactor coolant to condenser) seems to show that flow from the reactor coolant system (276 felm) stops at 0.1667 hours0.0193 days <br />0.463 hours <br />0.00276 weeks <br />6.342935e-4 months <br /> or 10 minutes.

However, without the MSLRM and its automatic MSIV closure, the MSIVs do not close and steam flow should continue for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> before isolation. Please explain this discrepancy, and if needed, provide the new analysis showing that the MSIVs remain open.

Reactor Systems Branch (SRXB)

Reviewer: Muhammad Razzaque SRXB-RAI-1 The NRC staff understands that the MSLRM trip function is currently credited for initiating automatic reactor scram; and a PCIS isolation including automatic closure of the MSIVs, MSL drain valves, MSL sample line valves, RHR system sample line valves, and Reactor Recirculation loop sample line valves in the current analysis of record for the design-basis CRDA at PBAPS.

a) In addition to CRDA, clarify whether the above trip function is currently credited for any other accident or transient analyses. If credited, discuss the events, including any plan to eliminate the trip function and resulting impacts on the outcome for those events.

b) The proposed TS changes will defeat portions of MSLRM high radiation trip function logic circuitry in the RPS and PCIS. Will there be any impact on the operation of the RPS or PCIS with respect to other intended safety functions. If so, discuss.

SRXB-RAI-2 Operating data presented in GE topical report NED0-31400A indicates that the MSLRMs have initiated eight reactor shutdowns from 1980 through October 1992, but none of the shutdowns were the result of fuel degradation. The shutdowns were the result of instrument failures, chemistry excursions, radiation monitor maintenance errors, and other causes.

Based on PBAPS plant-specific operating experience, has a plant shutdown ever resulted that was initiated specifically by the MSLRM trip function? If so, discuss the cause for those MSLRM trip function initiations, including whether any of the shutdowns were the result of actual fuel degradation, and whether the shutdown was unnecessary.

SRXB-RAI-3 A CRDA is one of the postulated boiling water reactor accidents when significant fuel damage is predicted to occur. In order for the NRC staff to understand the impact of the proposed license amendment on the CRDA analytical results, provide the following additional information in relation to the current analysis of record, and how the proposed changes would impact, if any, the degree of fuel damage:

a) Other than to eliminate the MSLRM trip and the related isolation functions proposed for the CRDA in the licensee's application, will there be any other changes of parameters and assumptions that are made for a CRDA analysis at PBAPS? If so, discuss the changes and its impact on the CRDA analysis results.

b) In the CRDA analysis, which trip function of the RPS is credited to scram the reactor, and does this change as a result of eliminating the MSLRM high radiation trip function? If so, discuss the impact of the change.

c) Other than radiological consequences, discuss whether there is any impact of eliminating the MSLRM high radiation trip function on the degree of fuel damage during a CRDA or any other adverse impact on the core or the plant. Is the number of fuel rods predicted to fail and melt changed for a CRDA as a result of eliminating the MSLRM high radiation trip function?

If so, discuss.

December 12, 2014 MEMORANDUM TO: Meena K. Khanna, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM: Richard B. Ennis, Senior Project Manager IRA!

Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

SUBJECT:

PEACH BOTTOM ATOMIC POWER STATION, UNITS 2 AND 3, DRAFT REQUEST FOR ADDITIONAL INFORMATION (TAC NOS.

MF4757 AND MF4758)

The attached draft request for additional information (RAI) was transmitted on December 12, 2014, to Mr. Richard Gropp of Exelon Generation Company, LLC (Exelon, the licensee). This information was transmitted to facilitate an upcoming conference call in order to clarify the licensee's amendment request for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, dated September 3, 2014. The proposed amendment would revise the Technical Specifications (TSs) to eliminate the Main Steam Line Radiation Monitor (MSLRM) from initiating: (1) a Reactor Protection System (RPS) automatic reactor scram; and (2) a Primary Containment Isolation System (PCIS) isolation including automatic closure of the Main Steam Line Isolation Valves (MSIVs), Main Steam Line (MSL) drain valves, MSL sample line valves, Residual Heat Removal (RHR) system sample line valves, and Reactor Recirculation loop sample line valves.

Existing requirements for the Mechanical Vacuum Pump (MVP) would be retained in the Technical Requirements Manual (TRM).

The draft RAI was sent to Exelon to ensure that the questions are understandable, the regulatory basis for the questions is clear, and to determine if the information was previously docketed. This memorandum and the attachment do not convey or represent an NRC staff position regarding the licensee's request.

Docket Nos. 50-277 and 50-278

Attachment:

Draft RAI DISTRIBUTION PUBLIC BGreen, NRR/DRA/APHB LPL 1-2 R/F KBucholtz, NRR/DRA/ARCB RidsNrrDoriLpl1-2 Resource MRazzaque, NRR/DSS/SRXB RidsNrrDoriDpr Resource RidsNrrPMPeachBottom Resource ACCESSION NO.: ML14349A707 OFFICE LPL 1-2/PM NAME REnnis DATE 12/12/14 OFFICIAL RECORD COPY