RS-17-079, Response to Request for Additional Information Regarding the Permanent Extension of Leak Rate Testing

Response to Request for Additional Information Regarding the Permanent Extension of Leak Rate Testing

ML17152A346
Person / Time
Site:	Clinton
Issue date:	06/01/2017
From:	Simpson P Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-17-079 CL-LAR-09, Rev. 0
Download: ML17152A346 (9)

Text

4300 Winfield Road A-Warrenville, IL 60555 14111111innow .

Amwr Exelon Generation G30 657 2000 Office RS-17-079 10 CFR 50.90 June 1, 2017 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket Nos. 50-461

Subject:

Response to Request for Additional Information Regarding the Permanent Extension of Leak Rate Testing Clinton Power Station, Unit 1

References:

1. Letter from Patrick R. Simpson (Exelon Generation Company, LLC) to U.S.

NRC, "License Amendment Request to Revise Technical Specification Section 5.5.13, 'Primary Containment Leakage Rate Testing Program,' for Permanent Extension of Type A and Type C Leak Rate Test Frequencies,"

dated January 25, 2016 (ML16025A182)

2. Letter from Patrick R. Simpson (Exelon Generation Company, LLC) to U.S.

NRC, "Response to Request for Additional Information Concerning License Amendment Request to Revise Technical Specification Section 5.5.13,

'Primary Containment Leakage Rate Testing Program,' for Permanent Extension of Type A and Type C Leak Rate Test Frequencies," dated March 2, 2017 (ML17062A584)

3. Email from Jennie Rankin (U.S. NRC) to John L. Schrage (Exelon Generation Company, LLC), "Clinton Power Station, Unit 1 - Request for Additional Information Regarding the Permanent Extension of Leak Rate Testing (CAC No. MF7290)," dated May 2, 2017 (ML17125A321)

4. Teleconference Between U.S. NRC (J. Rankin, et al) and Exelon Generation Company, LLC (J. Schrage, et al) on May 2, 2017 In Reference 1, Exelon Generation Company, LLC (EGC) requested an amendment to Facility Operating License (FOL) No. NPF-62 for Clinton Power Station (CPS), Unit 1. The proposed amendment would revise FOL Appendix A, Technical Specification (TS) 5.5.13, "Primary Containment Leakage Rate Testing Program" to allow for the permanent extension of the Type A Integrated Leak Rate Testing (ILRT) and Type C Leak Rate Testing frequencies.

June 1, 2017 U.S. Nuclear Regulatory Commission Page 2 EGC transmitted a response to 13 requests for additional information (RAls) related to the proposed license amendment in Reference 2.

In Reference 3, the NRC transmitted one additional RAI, and provided clarification to EGC during the Reference 4 teleconference.

The Enclosure to this letter provides the information requested in Reference 3.

There are no regulatory commitments contained within this letter.

If you have any questions concerning this letter, please contact Mr. John L. Schrage at (630) 657-2821.

1 declare under penalty of perjury that the foregoing is true and correct. Executed on the 1" day of June 2017.

Respectfully, Patrick R. Simpson Manager Licensing Exelon Generation Company, LLC

Enclosure:

RAI Response for ILRT LAR for Clinton Power Station, RM Documentation No.

CL-LAR-09, Revision 0 cc: NRC Regional Administrator, Region III NRC Senior Resident Inspector Clinton Power Station Illinois Emergency Management Agency Division of Nuclear Safety

Enclosure RAI Response for ILRT LAR for Clinton Power Station RM Documentation No. CL-LAR-09, Revision 0

1~ Exelon Ri~`. lAanagamment Team RM DOCUMENTATION NO. CL-LAR-09 REV: 0 PAGE NO. I STATION: Clinton Power Station UNIT(s) AFFECTED: 1 TITLE: Round 2 RAI Response for ILRT LAR for Clinton Power Station

SUMMARY

The purpose of this document is to provide Exelon Generation's responses to Requests for Additional Information (RAls) associated with Clinton ILRT License Amendment Request, This is a Category I RM Document IAW ER-AA-600-1012, which requires independent review and approval.

Review required after periodic Update X ] Internal RM Documentation External RM Documentation Electronic Calculation Data Files: N/A Method of Review: [X ] Detailed ] Alternate Review of External Document This RM documentation supersedes: N/A Prepared by: Garrett Snedeker 5/30/17 Print Sign Date Reviewed by: John E. Steinmetz 1 1 5/30/17 Print Sign Date Reviewed by: Tony Hable 1 5/30/17 Print in Date Approved by: Eugene M. Kelly 5/30/17 Print Sin Date Rev. 0

CL-LAR-08 RESPONSE TO RAls ASSOCIATED WITH ILRT LAR FOR CLINTON POWER STATION RAI 2-1 ni iPOinn Facts & Observation (F&O) 6-8 identified that the probabilistic risk assessment (PRA) takes credit for opening doors to ensure cooling for the Emergency Core Cooling System (ECCS) pump rooms, but no formal engineering analyses was provided. In RAI 2.b, the NRC staff requested justification for the resolution of this F&O. As indicated in the F&O resolution and in the response to RAI 2.b, a computational fluid dynamics (CFD) simulation has been performed for Residual Heat Removal (RHR)-B to support the credit for opening doors. The licensee stated in the RAI response that the RHR-A pump room is judged as having similar behavior to RHR-B because the rooms are generally symmetrical in terms of dimensions. The licensee also stated that other ECCS pump rooms are comparable and provided information on the volume and heat loads for those rooms.

Based on this information some of the ECCS rooms (RHR-C, High Pressure Core Spray, and Low Pressure Core Spray) do not appear to be similar to RHR-B. These rooms have higher heat loads as well as higher heat load per unit volume than the RHR-B room. Therefore, the CFD calculation performed for RHR-13 pump room cannot be considered applicable or bounding for these rooms. The RAI response also stated that a "phenomenological failure term" is included in the PRA model to represent the possibility that the rooms are dissimilar, however the assigned failure probability is not justified. As a result, the justification sought by the staff in RAI 2.b has not been provided for all ECCS rooms and F&O 6-8 appears to remain unresolved.

Justify the credit for opening doors for the remaining ECCS rooms (e.g., CFD analyses) or alternatively, provide the results of a quantitative sensitivity analysis that assesses the impact of removing the credit for opening doors of the ECCS rooms on the current application.

Response to RAI 2-1 Since no formal engineering analysis is currently available to further justify credit for opening doors for ECCS rooms RHR C, High Pressure Core Spray (HPCS), and Low Pressure Core Spray (LPCS), a quantitative sensitivity analysis was performed to eliminate credit in the PRA model. The following table provides the results with no credit for opening of the doors for failure of room cooling in the RHR C, HPCS and LPCS rooms.

Rev. 0 2

CL-LAR-08 BASE CDF1" NEW CDF``'

CDF 2.23E-6/yr 2.49E-6/yr LERF 1. 1 6E-7/vr 1.34E-7/vr Notes to Table:

Base CDF and LERF from the original ILRT LAR analysis.

CDF and LERF based on removing credit for opening the doors for loss of room cooling for RHR C, HPCS, and LPCS rooms, The new results were used to re-create Tables 5.6-1, 5.7-1, 5.7-2, 5.7-3, and 5.7-4 from the ILRT LAR analysis.

TABLE 5.6-1 CPS ILRT/DWBT CASES:

BASE, 3 TO 10, AND 3 TO 15 YR EXTENSIONS (INCLUDING AGE ADJUSTED STEEL CORROSION LIKELIHOOD BASE CASE EXTEND TO EXTEND TO 3 IN 10 YEARS 1 IN 10 YEARS 1 IN 15 YEARS DOSE CDF PERSON- CDF PERSON- CDF PERSON-EPRICLASS PER-REM (1/YR) REMIYR (11YR) REMNR (1/YR) REMIYR 1 2.71 E+03 9.18E-07 2.49E-03 8.81 E-07 2.39E-03 8.54E-07 2.32E-03 2 5.48E+05 3.32E-07 1.82E-01 3.32E-07 1.82E-01 3.32E-07 1.82E-01 3a 2.71 E+04 1.35E-08 3.65E-04 4.48E-08 1.22E-03 6.73E-08 1.83E-03 3b 2.71 E+05 2.74E-09 7.43E-04 9.14E-09 2.48E-03 1.38E-08 3.74E-03 7LERF 5.48E+05 1.33E-07 7.28E-02 1.33E-07 7.28E-02 1,33E-07 7.28E-02_

7 non-LERF 3.37E+05 1.09E-06 3.71 E-01 1.09E-06 3.71 E-01 1.09E-06 3.71 E-01 8 5.48E+05 1.55E-09 8.49E-04 1.55E-09 8.49E-04 1.55E-09 8.49E-04 Total 2.49E-06 0.631 2.49E-06 0.633 2.49E-06 0.635 I LRT Dose Rate 1.11 E-03 3.70E-03 5.57E-03 from 3a and 3b Delta From 3 yr --- 2.48E-03 4.28E-03 Total Dose Rate From 10 yr --- 1.80E-03 3b Frequency (LERF) 2.74E-09 9.14E-09 1.38E-08 From 3 yr --- 6.41 E-09 1.10E-08 Delta 3b LERF --- ---

From 10 yr 4.64E-09 CCFP % 62.64% 62.90% 63.09%

From 3 yr --- 0.26% 0.44%

Delta CCFP % ---

From 10 yr 0.19%

Rev. 0 3

CL-LAR-08 TABLE 5.7-1 OTHER HAZARD GROUP CONTRIBUTOR

SUMMARY

OTHER HAZARD INITIATOR GROUP CDF (1/YR)

Seismic 9 1.7E-05 Internal Fire [81 6.0E-06" High Winds/Tornadoes Screened External Floods Screened Transportation and Nearby Facility Accidents Screened Total (for initiators with CDF available) 2.3E-05 Internal Events CDF 2.23E-06121 External Events Multiplier 10.3112.)

Note to Table 5.7-1:

The Clinton Fire PRA does not credit opening the doors for ECCS room cooling, therefore, there is no change in Fire CDF.

(2)

The External events multiplier was conservatively left the same as the original ILRT submittal. Using the updated CDF would results in an external events multiplier of 9.24.

TABLE 5.7-2 CPS 3B (LERF) AS A FUNCTION OF ILRT/DWBT FREQUENCY FOR INTERNAL AND EXTERNAL EVENTS (INCLUDING AGE ADJUSTED STEEL CORROSION LIKELIHOOD) 313 313 313 FREQUENCY FREQUENCY FREQUENCY (3-PER-10 (1-PER-10 (1-PER-15 YEAR YEAR YEAR LERF ILRT/DWBT ILRT/DWBT) ILRT/DWBT) INCREASE(') -

Internal Events 2.74E-09 9.14E-09 1.38E-08 1.10E-08 Contribution Other Hazard Group Contribution (Internal 2.82E-08 9.43E-08 1.42E-07 1.14E-07 Events CDF x 10.31 Combined 3.10E-08 1.03E-07 1.56E-07 1.25E-07 Note to Table 5.7-2:

Associated with the change from the baseline 3-per-10 year frequency to the proposed 1-per-15 year frequency.

Rev. 0 4

CL-LAR-08 TABLE 5.7-3 COMPARISON TO ACCEPTANCE CRITERIA INCLUDING OTHER HAZARD GROUPS CONTRIBUTION FOR CPS CONTRIBUTOR j ALERF PERSON-REM/YRt'~ \CCFP(2)

CPS Internal Events 1.10E-8/ r 4.28E-03/ r 0.68% 0.44%

CPS Other Hazard 1.14E-7/yr 4.42E-02/yr (0.68%) I 0.44%

Groups CPS Total 1.25E-7! r 4.85E-02/ r 0.68% 0.44%

<1.0 person-rem/yr Acceptance Criteria j <1.0E-6/yr o <_1.5%

or <1.0/0 Notes to Table 5.7-3:

77 The EPRI Class (1, 2, 7, 8) release Person-Rem/yr are assumed to be the same percentage relative to base risk (0.73%) for internal and external events.

(2)

The Probability of DW and WW leakage due to the ILRT/DWBT extension is assumed the same for both Internal and External Events, therefore the percentage change for CCFP remains constant (0.44%).

TABLE 5.7-4 IMPACT OF 15-YR ILRT EXTENSION ON LERF (313) FOR CPS Internal Events LERF 1.34E-07/yr Internal Fire LERF 9.21 E-07/yr i Other Hazard Group LERF 8.84E-07/yr (Internal Events LERF x 7.62)

Internal Events LERF due to ILRT 1.38E-08/yr Class 3b at 15 ears 0)

Other Hazard group LERF due to ILRT at 15 years 1.42E-07/ r Total 2.09E-061 r Note to Table 5.7-4:

Including age adjusted steel corrosion likelihood.

As can be seen, the impacts from the sensitivity are as follows:

1. Change in LERF = 1.25E-7/yr, which is slightly above the 1.0E-7/yr upper boundary for the "very small" risk increase as defined in RG 1.174, but at the bottom of the band for "small" risk increase.

2. Change in population dose rate is 4.85E-2 person-rem/yr (0.68%), which is less than 1.0 person-rem/year or 1 % of the total population dose.

3. Change in CCFP is 0.44%, which is less than 1.5%.

Rev. 0

Similar to the original IRT LAR submittal the 1.25E-07/yr increase in LERF due to the combined hazard events from extending the CPS I'-RT/DWBT frequency from 3-per-10 years to 1-per-15 years falls within Region ll between 'I E-7 to 1E-6 per reactor year

("Small Change" in risk) of the RG 1.174 acceptance guidelines. Per RG 1.174, when t,ie calculated increase in LER due to the proposed plant change is in the "Small Change" range, the risk assessment must also reasonably show that the total LERF is ess than 1E-5/yr. S:mclar bounding assumptions ~egarding the external event contributions that were made above are used for the total LERF estimate. As can be seen in Table 5.7-4 above, tie estimated LERF 1"or CPS using the Fire LERF and CDF based multiplier approach for seismic is 2.09E-06/yr, which is less than the RG 1.174 required value of 1 E-5/yr.

.rev. 0