ML21189A044

NRR E-mail Capture - Request for Additional Information - Diablo Canyon Emergency Amendment Request to Revise Technical Specification 3.7.8, Auxiliary Saltwater (Asw) System

ML21189A044
Person / Time
Site:	Diablo Canyon
Issue date:	07/07/2021
From:	Samson Lee NRC/NRR/DORL/LPL4
To:	Richardson M Pacific Gas & Electric Co
References
L-2021-LLA-0123
Download: ML21189A044 (3)

Text

From: Lee, Samson Sent: Wednesday, July 7, 2021 5:36 PM To: Richardson, Michael

Subject:

Request for additional information - Diablo Canyon emergency amendment request to revise Technical Specification 3.7.8, Auxiliary Saltwater (ASW)

System (EPID L-2021-LLA-0123)

Background:

By letter dated July 7, 2021, Pacific Gas and Electric Company (PG&E or the licensee) submitted an emergency license amendment request (LAR) to revise the Technical Specification (TS) for the Diablo Canyon Nuclear Power Plant, Units 1 (Diablo Canyon or DCPP) (ADAMS Accession No. ML21188A214). The proposed amendments would provide a new TS 3.7.8 Condition A note to allow a one-time Completion Time (CT) of 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> to replace the ASW pump 1-1 motor during Cycle 23. The NRC staff has reviewed the LAR and determined that additional information is required to complete the review. The NRC staffs requests for additional information (RAIs) are listed below. The PG&E staff indicated that a clarification call is not necessary. The PG&E staff requested, and NRC agreed, to an RAI response by July 7, 2021.

The NRC staff considers that timely responses to RAIs help ensure sufficient time is available for staff review and contribute toward the NRCs goal of efficient and effective use of staff resources. Please note that if you do not respond to this request by the agreed upon date or provide an acceptable alternate date, we may deny your application for amendment under the provisions of Title 10 of the Code of Federal Regulations, Section 2.108. If circumstances result in the need to revise the agreed upon response date, please contact me at (301) 415-3168 or via e-mail Samson.Lee@nrc.gov.

Risk Insights:

RAI APLA-1 For DCPP ASW pump 1-1:

1. In the LAR, the licensee indicated that they will tailboard [pre-job brief] operators on providing backup cooling from firewater to charging pumps.

a. Are there any job performance measures for this activity?

b. Describe the nature of the reactor coolant pump (RCP) seals and any enhancement (i.e., Gen III SHIELD shutdown seal or Abeyance).

2. Will there be any restrictions on performing on-line maintenance for other systems, structures, and components (SSCs) during the extended allowable outage time (AOT)?

3. When doing the risk analysis, what assumptions were made on common cause failure (CCF) and why?

4. Was an all-hazards model used to estimate core damage frequency (CDF)/large early release frequency (LERF)?

RAI APLA-2 In the LAR, Section 3 under Risk Insights, it was stated that, The results demonstrate that ICCDP [incremental conditional core damage probability] and ICLERF [incremental conditional large early release frequency] are below the risk significance criteria of Regulatory Guide 1.174, 1.0E-06 and 1.0E-07, respectively. Therefore, the proposed separate one-time extension of TS 3.7.8 Condition A Required Action to 6-days for emergent maintenance for ASW Pump 1-1 Motor is considered to not be risk significant. It was not clear to the staff which measure of risk was used since Regulatory Guide (RG) 1.174 refers to CDF/LERF and CDF/LERF.

a. Clarify if ICLERP was intended in lieu of ICLERF and if so, should Regulatory Guide 1.177 guidance on iCCDP/iCLERP be cited for this one-time TS change?

b. If not, justify how RG 1.174 metrics were used to conclude that maintenance on ASW Pump 1-1 Motor is not risk significant.

Electrical Engineering:

RAI EEEB-1 In the LAR, the licensee stated that the proposed changes would revise the operating license to provide a new TS 3.7.8 Condition A note to allow a one-time CT of 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> to replace the ASW pump 1-1 motor during Cycle 23. Please clarify the type of the replacement motor and the specifications of both existing and replacement motors. Also, please confirm no load changes as the result of the motor replacement.

Reactor Systems:

RAI SNSB-1 The LAR states, The TS 3.7.9 Ultimate Heat Sink (UHS) requirements are currently being met with the UHS (Pacific Ocean) temperature below 64°F. Given that the safety analysis assumes a maximum ASW temperature of 64°F, provide information on the expected UHS temperature for the duration of the proposed 144-hour CT in order to assure that the single operable train of ASW will continue to meet the design basis.

Mechanical Engineering:

RAI EMIB-1 In Section 2.0, Detailed Description, under Reason for the Proposed Change, it is stated, It is expected an additional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the 72-hour completion time could be required to address contingency actions that may occur during the return of ASW Pump 1-1 to OPERABLE status. Provide a description of the contingency actions.

Hearing Identifier: NRR_DRMA Email Number: 1259 Mail Envelope Properties (SA1PR09MB8653A038DFDB80A139D5C9D39A1A9)

Subject:

Request for additional information - Diablo Canyon emergency amendment request to revise Technical Specification 3.7.8, Auxiliary Saltwater (ASW) System (EPID L-2021-LLA-0123)

Sent Date: 7/7/2021 5:35:47 PM Received Date: 7/7/2021 5:35:00 PM From: Lee, Samson Created By: Samson.Lee@nrc.gov Recipients:

"Richardson, Michael" <MJRm@pge.com>

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