ML19058A290

Request for Additional Information - High Pressure Service Water One Time TS Change

ML19058A290
Person / Time
Site:	Peach Bottom
Issue date:	02/27/2019
From:	Jennifer Tobin Plant Licensing Branch 1
To:	David Helker Exelon Generation Co, Exelon Nuclear
Tobin J
References
EPID L-2018-LLA-0265
Download: ML19058A290 (3)

Text

From: Tobin, Jennifer To: "Helker, David P:(GenCo-Nuc)"

Cc: Gropp Jr, Richard W:(GenCo-Nuc)

Subject:

Peach Bottom Units 2 and 3 - Request for Additional Information - High Pressure Service Water One Time TS Change (EPID L-2018-LLA-0265)

Date: Wednesday, February 27, 2019 11:51:00 AM

Dear Mr. Helker,

By letter dated September 28, 2018 (ADAMS Accession No. ML18275A023), Exelon Generation Company, LLC requested to change technical specifications for Peach Bottom Atomic Power Station Units 2 and 3. The proposed change would revise the design and licensing basis described in the final safety analysis report (as updated) to reduce the design pressure rating of the high pressure service water system.

The Nuclear Regulatory Commissions (NRC) staff is reviewing your submittal and has determined that additional information is needed to complete its review. The specific request for additional information (RAI) questions are provided below. These questions are being sent to ensure that the questions are understandable, the regulatory basis for the questions is clear, and to determine if the information was previously docketed. A clarification phone call was held February 27, 2019. Minor edits were made to the RAIs as a result of the call to correct typographical errors. A response to these RAIs is due within 30 days (by March 27, 2019).

Note: two RAIs had already been issued by NRC on January 16, 2019 (ADAMS Accession No. ML19017A047) and responded to on February 15, 2019 (ADAMS Accession No. ML19046A129) so the RAI numbering for these questions begin at #3.

If you have any questions, please contact me at (301) 415-2328. A copy of the RAIs will be made publicly available in ADAMS.

Thanks, Jenny Jenny Tobin Project Manager NRR/DORL/LPL-1 Office O9-C12 Phone 301-415-2328 REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST PROPOSED REDUCTION IN DESIGN PRESSURE FOR HIGH PRESSURE SERVICE WATER SYSTEM EXELON GENERATION COMPANY PEACH BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 DOCKET NO. 50-277 AND 50-278 EPID: L-2018-LLA-0265 By letter dated September 28, 2018 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML18275A023), Exelon requested a license amendment to reduce the design pressure rating of the High Pressure Service Water (HPSW) system at

Peach Bottom Atomic Power Station Units 2 and 3. The proposed change will provide additional corrosion margin in the HPSW pipe wall thickness, increasing the margin of safety. The proposed request will also temporarily revise the plant Technical Specifications (TS) Sections 3.6.2.3, "Residual Heat Removal (RHR) Suppression Pool Cooling," TS 3.6.2.4, "Residual Heat Removal (RHR) Suppression Pool Spray," TS 3.6.2.5, "Residual Heat Removal (RHR) Drywall Spray," and TS 3.7.1, "High Pressure Service Water (HPSW)

System."

To complete its review, the Nuclear Regulatory Commission (NRC) staff requests the following additional information.

RAI 3

Issue: In Section 2.2 of the license amendment request, last paragraph, the licensee stated that "...The proposed reduction in design pressure will provide for additional corrosion margin in pipe wall thickness, increasing the margin of safety for the existing piping" It is not evident that the submittal included the corrosion margin calculations, pipe diameter and wall thickness.

Request: Provide the following: (1) Pipe nominal pipe size (NPS), (2) Pipe nominal wall thickness, (3) the corrosion margin (allowance) after proposed modification, (4) the existing corrosion margin (allowance) with the current pressure inside the pipe, and (5) corrosion calculations and associated references.

RAI 4

Issue: In Section 2.2 of the license amendment request, first paragraph, the licensee stated that "[the system pressure] will be reduced from the current rating of 450 psig to a design pressure rating of approximately 200 psig. The final value is expected to fall between 190 psig and 230 psig in the detailed design with final vendor inputs" In Section 3.1, page 3, fourth paragraph, the licensee stated, " At maximum expected RHR system pressures, a pressure of 233 psig at the HPSW pump discharge is required to ensure HPSW side pressure exceeds RHR system pressure at the RHR heat exchanger" In Attachment 4, Peach Bottom UFSAR, Table 10.7.1, page 33 of the pdf file, the proposed pump shut off head is changed to 240 psig.

As shown above, the licensee mentioned various pressures--190, 200, 230, 233, and 240 psig. It is not clear the exact design pressure and maximum operating pressure in HPSW piping after modification. The NRC staff notes that there should be only one design pressure value, not a range of design pressure.

Request: (1) Provide the exact design pressure and maximum operating pressure in the HPSW piping system after the proposed modification. (2) Discuss the pressure that is used to calculate the corrosion margin.

RAI 5

Issue: In Attachment 5, page 6, of the license amendment request, the licensee discussed the replacement of existing valves and orifices. However, it is not evident that the licensee

discussed an examination that will be performed prior to installation/replacement to determine the condition of the HPSW piping.

Request: Discuss if inspections will be performed on the HPSW piping prior to hardware modifications to determine the general condition of the piping. If not, discuss whether the existing piping condition would support the replacement activities.

RAI 6

Issue: In the license amendment request, it is not evident that the licensee discussed (1) the examinations to accept the modification/installation, (2) the pressure test to demonstrate any potential leakage, and (3) functionality test to demonstrate the modified HPSW system will perform its intended function.

Request: (1) Discuss the acceptance examination that will be performed immediately after the hardware modification to demonstrate the structural integrity and leak tightness of the modified HPSW piping. If leakage occurs, discuss the acceptance criteria and how the leakage will be dispositioned. (2) Discuss whether the hardware modification will be performed based on the provisions of article IWA-4000 of the ASME Code,Section XI. If not, discuss the industry guidance that will be used as part of the hardware modifications.

(3) Discuss if a system leakage test will be performed in accordance with the ASME Code,Section XI, IWA-5000 and IWD-5000. If yes, discuss what would be the pressure used for the system leakage test. If a system leakage test will not be performed, provide justification.

(4) Discuss whether a functionality or operability test will be performed to demonstrate that the proposed pressure reduction will achieve the intended function of the HPSW system.

RAI 7

Issue The NRC staff finds that with the proposed pressure reduction, the pipe stresses will be different from the original design basis for the HPSW piping. The license amendment request did not appear to discuss the reanalysis of the existing pipe stress analysis of HPSW piping based on the original construction Code, USAS B31.1-1967 edition, as a result of proposed pressure reduction in HPSW piping.

Request Because of the proposed pressure reduction, discuss if a reanalysis is needed to evaluate pipe stresses for the HPSW piping in accordance with the original construction code, USAS B31.1-1967 edition.