ML19336A014

NRR E-mail Capture - RAI: Hatch Emergency TS 3.7.1 Residual Heat Removal Service Water (RHRSW) System LAR

ML19336A014
Person / Time
Site:	Hatch
Issue date:	12/01/2019
From:	John Lamb NRC/NRR/DORL/LPL2-1
To:	Coleman J Southern Nuclear Operating Co
References
Download: ML19336A014 (4)

Text

From: Lamb, John Sent: Sunday, December 1, 2019 6:54 AM To: Coleman, Jamie Marquess Cc: Enfinger, Timothy Lee; Sparkman, Wesley A.

Subject:

RAI: Hatch Emergency TS 3.7.1 LAR Importance: High Ms. Coleman:

By application dated November 29, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19333B967), Southern Nuclear Operating Company, Inc.

(SNC, the licensee), requested changes to the Technical Specifications (TSs) for the Edwin I.

Hatch Nuclear Plant (HNP), Unit No. 1. The proposed change is for TS 3.7.1, Residual Heat Removal Service Water (RHRSW) System.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed your application and has determined that additional information is needed to complete its review. The NRC staff has developed the below request for additional information (RAI) in support of its review of the subject license amendment request (LAR).

SNC requested the proposed LAR on an emergency basis for the HNP, Unit 1, RHRSW System, pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Section 50.91(a)(5);

therefore, the NRC staff needs the RAI responses within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> from the time of this email.

If you have questions, you can contact me at 301-415-3100.

Sincerely, John G. Lamb, Senior Project Manager REQUEST FOR ADDITIONAL INFORMATION (RAI)

By application dated November 29, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19333B967), Southern Nuclear Operating Company, Inc.

(SNC, the licensee), requested changes to the Technical Specifications (TSs) for the Edwin I.

Hatch Nuclear Plant (HNP), Unit No. 1. The proposed change is for TS 3.7.1, Residual Heat Removal Service Water (RHRSW) System.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed your application and has determined that additional information is needed to complete its review. The NRC staff has developed the following request for additional information (RAI) in support of its review of the subject license amendment request (LAR).

Regulatory Analysis:

Section 182a of the Atomic Energy Act of 1954, as amended (the Act), requires applicants for nuclear power plant operating licenses to include TS as a part of the license. The Commissions regulatory requirements related to the content of TS are set forth in 10 CFR 50.36, which requires that the TS include items in eight specific categories, including (1) safety limits, limiting

safety system settings and limiting control settings; (2) limiting conditions for operation (LCO);

(3) surveillance requirements (SR); (4) design features; (5) administrative controls; (6) decommissioning; (7) initial notification; and (8) written reports. 10 CFR 50.36(c)(2)(i) states that TS will contain LCO which are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When a limiting condition for operation of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the technical specifications until the condition can be met.

APLA-RAI-1 Describe and justify the status of all RHRSW pumps and the basis for the statement SNC does not believe the failure of the two new pumps originate for a common cause.

APLA-RAI-2 Provide a discussion and justification on how the Common Cause Failure Potential for the three remaining RHRSW pumps was modelled (e.g., what is the failure probability of pump A, C, and D in the current risk estimates). The specific values that were provided are insufficient for the staff to understand how CCF is treated.

APLA-RAI-3 The submittal states that Rev 7 model was used that addresses specific issues identified in the Hatch NFPA-805 and 50.69 RAI responses. The NRC staff notes that numerous modifications have been proposed as part of the NFPA-805 LAR. Two probabilistic risk assessment (PRA) results are required to support an NFPA-805 LAR, the deterministically compliant plant PRA model and the variant (i.e., post-transition) plant PRA model.

Confirm that the PRA results provided to support the emergency amendment request represent the current as-built and as-operated plant, and addressed all the modeling issues identified in the RAIs and associated responses for NFPA 805 and 50.69, or otherwise provide justification why the LAR risk estimate constitute a bounding estimate.

APLA-RAI-4 According to Regulatory Guide (RG) 1.177, Tier 2: Avoidance of Risk-Significant Plant Configurations, a licensee must provide reasonable assurance that risk significant plant equipment outage configurations will not occur when specific plant equipment is out-of-service in accordance with the proposed TS change.

Provide the list of compensatory measured that are to be implemented during this allowed outage time (AOT) extension. Provide additional discussions of the statement only two basic events had a [risk achievement worth] RAW increase greater than 2.0: there were a common cause failure and a [human error probability] HEP combination and how is that reflected in the compensatory measures.

STSB-RAI-5 In its application, the licensee described issues with restoring the 1B RHRSW pump to operable status within 30 days as required by TS 3.7.1 Required Action A.1. However, the 1D RHRSW pump has shown indication of degradation in previous surveillances. The licensee made no mention of the 1D RHRSW pump (or any of the remaining RHRSW pumps) in their LAR. The NRC staff notes the proposed Note for TS 3.7.1 Required Action A.1 Completion Time is open-ended within the expiration date of December 18, 2019. This would allow the licensee to invoke the extended Completion Time to any of the currently operable RHRSW

pumps within the extended period without providing additional pump-specific data or justification.

Provide technical justification for allowing the extended Completion Time be applicable to any of the currently operable RHRSW pumps or modify the proposed Note by restricting usage to the 1B RHRSW pump.

DORL-RAI-6 The 1B RHRSW pump failed its pre-service test on November 21, 2019. The Commission expects its licensees to apply for license amendments in timely fashion, as stated in 10 CFR 50.91(a)(5). Why did SNC not submit an exigent TS change after the 1B RHRSW failed its pre-service test on November 21, 2019? Please explain why SNC could not avoid the current emergency situation.

SCPB-RAI-7 The system is described as two subsystems of two pumps each, separated by normally closed motor-operated cross-tie valves. Two pumps in either subsystem provide the required cooling to maintain safe-shutdown conditions. Please provide the following information addressing the likelihood that the RHRSW system as configured during repair activities could successfully mitigate challenges of moderate frequency:

a. Describe the RHRSW function success criteria (i.e., number of operating pumps necessary for adequate decay heat removal on a best-estimate (PRA) basis) for a loss of offsite power transient scenario and for other events of reasonably high frequency such as a stuck open safety relief valve.

b. If more than one RHRSW pump is necessary for either event, explain whether the division cross-tie valves have been credited in the risk assessment and the criteria used for successful operation of the cross-tie with respect to configuration of operating pumps, available time for manual actions, and associated procedures and operator training.

SCPB-RAI-8 Section 2.2 of Attachment 4 to the license amendment request describes a single compensatory measure related to emergency diesel generator availability. However, this section mentions that the main condenser and condensate system provide an alternate heat sink if the RHRSW system is unavailable. Please provide justification for excluding compensatory measures to more fully protect the unaffected division or to restrict switchyard work, which could reduce the likelihood of a loss of offsite power transient, the availability of the alternate heat sink (condenser), and pose a challenge to the emergency diesel generators necessary for power to the remaining RHRSW pumps.

SCPB-RAI-9 Section 1 of the Enclosure to the license amendment request states that neither the licensee nor the vendor believes the failures of the two new RHRSW pumps originate from a common cause. However, the license amendment request has not addressed operating experience for similar deep draft vertical turbine pumps. Describe how the test failure and unexplained shaft heating were evaluated for potential commonality with the observed failure modes of similar pumps in the Southern Nuclear Operating Company fleet.

Hearing Identifier: NRR_DRMA Email Number: 326 Mail Envelope Properties (SN6PR0901MB2399482C29356F7D88087AD3FA400)

Subject:

RAI: Hatch Emergency TS 3.7.1 LAR Sent Date: 12/1/2019 6:54:15 AM Received Date: 12/1/2019 6:54:00 AM From: Lamb, John Created By: John.Lamb@nrc.gov Recipients:

"Enfinger, Timothy Lee" <TLENFING@SOUTHERNCO.COM>

Tracking Status: None "Sparkman, Wesley A." <WASPARKM@southernco.com>

Tracking Status: None "Coleman, Jamie Marquess" <JAMIEMCO@SOUTHERNCO.COM>

Tracking Status: None Post Office: SN6PR0901MB2399.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 8602 12/1/2019 6:54:00 AM Options Priority: High Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: