ML18344A075

NRR E-mail Capture - Request for Additional Information - Sequoyah 1 and 2, Request to Modify Essential Raw Cooling Water Motor Control Center Breakers and to Revise Updated Final Analysis Report (SQN-TS-17-04)

ML18344A075
Person / Time
Site:	Sequoyah
Issue date:	12/10/2018
From:	Samson Lee Plant Licensing Branch 1
To:	Wells R Tennessee Valley Authority
References
L-2018-LLA-0060
Download: ML18344A075 (3)

Text

NRR-DMPSPEm Resource From: Lee, Samson Sent: Monday, December 10, 2018 8:12 AM To: Wells, Russell Douglas Cc: Hon, Andrew; Shoop, Undine

Subject:

Request for additional information - Sequoyah Nuclear Plant, Units 1 and 2, Request to Modify Essential Raw Cooling Water Motor Control Center Breakers and to Revise Updated Final Analysis Report (SQN-TS-17-04) (EPID: L-2018-LLA-0060)

By the letter dated March 9, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18071A349), Tennessee Valley Authority (TVA), submitted a request to amend the licenses for Sequoyah Nuclear Plant (SQN) Units 1 and 2 to modify the essential raw cooling water (ERCW) motor control center (MCC) breakers and revise the Updated Final Safety Analysis Report (UFSAR). SQN implemented a design change to remove the existing mechanical (Kirk Key) interlocking scheme from the feeder breakers and tie breakers for ERCW MCCs 1A-A and 2A-A.

The mechanical interlock for the ERCW MCC feeder breakers was replaced with administrative (procedural) controls. The NRC staff has reviewed the license amendment request (LAR) and determined that additional information is required for the staff to complete the review. The staffs request for additional information (RAI) follows. The draft RAI was emailed in draft form on November 30, 2018, and the TVA staff responded that they did not need a clarification call on the draft RAI and there was no proprietary or sensitive information. The TVA staff requested, and NRC agreed, a RAI response date of January 31, 2019, due to the current outages for both units and upcoming holidays.

REGULATORY BASIS Appendix A, General Design Criteria for Nuclear Power Plants to Title 10 of the Code of Federal Regulations (10 CFR)

Part 50, Domestic Licensing of Production and Utilization Facilities states the following:

• Criterion 5Sharing of structures, systems, and components, requires that structures, systems, and components important to safety, including the onsite electric power supplies and distribution systems, shall not be shared among nuclear power units unless it can be shown that such sharing will not significantly impair their ability to perform their safety functions, including, in the event of an accident in one unit, an orderly shutdown and cool down of the remaining units.

• Criterion 17Electric power systems, requires, in part, that the onsite electric power supplies, including the onsite electric distribution system, shall have sufficient independence and redundancy to perform their safety functions assuming a single failure.

The NRC staff reviews the human performance aspects of LARs using the guidance in Standard Review Plan Chapter 18 and NUREG-1764 Rev. 1, Guidance for the Review of Changes to Human Actions (ADAMS Accession No. ML072640413). In accordance with the generic risk categories established in Appendix A to NUREG-1764, the tasks under review involve human actions associated with a risk-important system. Due to the risk importance, the NRC staff will perform a Level II human factors review per the guidance in Section 4 of NUREG-1764, Rev. 1. NUREG-1764, Section 4, Level II Review Guidance, includes the following 4 areas of review:

1. General Deterministic Review

2. Analysis

3. Design of Human System Interface (HSI), Procedures, and Training

4. Human Action Verification REQUESTS FOR ADDITIONAL INFORMATION 1

RAI 1: The general deterministic review guidance in NUREG-1764 states that the licensee should provide adequate assurance that the change does not compromise defense in depth. If the administrative controls were to fail (tie-breakers left closed), discuss whether the normal and alternate power supplies aligned to an ERCW MCC belonging to a train (e.g., A train) could be out of phase if the 6.9kV shutdown boards (1A and 2A) are powered from offsite power.

RAI 2: The analysis review guidance in NUREG-1764 states that the licensee should perform a functional and task analysis to identify how personnel will know when the human action is necessary and has been performed correctly. Describe the procedures and administrative controls that will be used to:

• Identify when it is acceptable to align the alternate power supply to an ERCW MCC (to ensure that the alternate power supply is only aligned for maintenance purposes),

• Identify when it is not appropriate to perform the action (to ensure that the alternate power supplies are not aligned when powered from the emergency diesel generators),

• Verify that the ERCW bus that will be powered by its alternate power supply is de-energized prior to aligning the alternate supply, and

• Verify that the breaker alignment is correct after restoration of normal breaker alignment.

RAI 3: The HSI, procedures, and training review guidance in NUREG-1764 states that the licensee should describe any known operating experience issues. Describe any relevant operating experience related to failure of administrative controls, breaker manipulations, or concurrent/independent verification techniques and how that operator experience has been considered in the proposed LAR.

2

Hearing Identifier: NRR_DMPS Email Number: 702 Mail Envelope Properties (Samson.Lee@nrc.gov20181210081222)

Subject:

Request for additional information - Sequoyah Nuclear Plant, Units 1 and 2, Request to Modify Essential Raw Cooling Water Motor Control Center Breakers and to Revise Updated Final Analysis Report (SQN-TS-17-04) (EPID: L-2018-LLA-0060)

Sent Date: 12/10/2018 8:12:22 AM Received Date: 12/10/2018 8:12:22 AM From: Lee, Samson Created By: Samson.Lee@nrc.gov Recipients:

"Hon, Andrew" <Andrew.Hon@nrc.gov>

Tracking Status: None "Shoop, Undine" <Undine.Shoop@nrc.gov>

Tracking Status: None "Wells, Russell Douglas" <rdwells0@tva.gov>

Tracking Status: None Post Office:

Files Size Date & Time MESSAGE 4805 12/10/2018 8:12:22 AM Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received: