NL-11-0298, Joseph M. Farley, Units 1 and 2, Edwin I. Hatch, Units 1 and 2, and Vogtle, Units 1 and 2, Comments on Draft NRC Regulatory Issue Summary 2011-xx, Adequacy of Station Electric Distribution System Voltages.

Joseph M. Farley, Units 1 and 2, Edwin I. Hatch, Units 1 and 2, and Vogtle, Units 1 and 2, Comments on Draft NRC Regulatory Issue Summary 2011-xx, Adequacy of Station Electric Distribution System Voltages.

ML110480403
Person / Time
Site:	Hatch, Vogtle, Farley, 05000026
Issue date:	02/17/2011
From:	Ajluni M J Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-11-0298, NRC-2011-0013
Download: ML110480403 (1)

Text

Mark J. Ajluni, P.E. Southern Nuclear Nuclear Licensing Director Operating Company, Inc. 40 Inverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 February 17, 2011 Tel 205.992.7673 Fax 205.992.7885 Docket Nos.: 50-321 50-348 50-424 sa....lHIiJIN ..\ 50-366 50-364 50-026 COMPANY NL-11-0298 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Edwin I. Hatch Nuclear Vogtle Electric Generating Comments on Draft NRC Regulatory Issue Summary 2011-XX, "Adequacy Station Electric Distribution System Docket ID Ladies and Gentlemen:

In a January 18, 2011 Federal Register Notice (76FR 2924) the Nuclear Regulatory Commission (NRC) requested public comments on a Draft NRC Regulatory Issue Summary (RIS) 2011-XX, "Adequacy of Station Electric Distribution System Voltages".

This letter is to advise that Southern Nuclear Operating Company (SNC) endorses the comments submitted by NEI. SNC comments are provided in Enclosure

1. Respectfully submitted, Sincerely, Trkl }M. J, Ajluni Nuclear licenSing Director MJAlGALllac

Enclosures:

1, Comments on Draft NRC Regulatory Issue Summary 2011-XX "Adequacy of Station Electric Distribution System Voltages" Docket I D NRC-20 11-0013 U. S. Nuclear Regulatory Commission NL-11-0298 Page 2 Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. L. M. Stinson, Vice President Fleet Operations Support-Farley Mr. D. R. Madison, Vice President

-Hatch Mr. T. E. Tynan, Vice President

-Vogtle Ms. P. M. Marino, Vice President

-Engineering RType: CGA02.001 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. R. E. Martin, NRR Project Manager -Farley, Hatch and Vogtle Mr. E. L. Crowe, Senior Resident Inspector

-Farley Mr. E. D. Morris, Senior Resident Inspector

-Hatch Mr. M. Cain, Senior Resident Inspector

-Vogtle Mr. P. G. Boyle, NRR Project Manager Joseph M. Farley Nuclear Edwin I. Hatch Nuclear Vogtle Electric Generating Comments on Draft NRC Regulatory Issue Summary "Adequacy of Station Electric Distribution System Docket 10 Enclosure 1 Comments on Draft NRC Regulatory Issue Summary 2011-XX, "Adequacy of Station Electric Distribution System Voltages" Docket 10 NRC-2011-0013 Comments on Draft NRC Regulatory Issue Summary 2011-XX, "Adequacy of Station Electric Distribution System Voltages" Docket 10 NRC-2011-0013 10 Section, Page, Line Number 1 General 2 General 3 General Comment Include a definition of key terms (ex. Normal grid sustained degraded The RIS does not address completely the specific in the PSB-1 (ADAMS Accession No.

Arkansas Nuclear One (ADAMS No.ML0311801180), and Millstone (ADAMS Accession ML093521388) documents.

In some cases specific positions the above documents were omitted from the The RIS lacks adequate guidance to perform the calculation(s) without additional interpretations by the and auditors as to the intent of the provided Proposed Resolution Include missing positions especially those related to determining minimum expected offsite system voltages and testing. Provide a guideline with examples on how to perform the calculation(s) including expected assumptions, other considerations, and criteria to be used for acceptance.

Comments on Draft NRC Regulatory Issue Summary 2011-XX, "Adequacy of Station Electric Distribution System Voltages" Docket ID NRC-2011-0013 ID Section, Page, Line Number 4 General Comment The RIS provides some examples of plants that have NRC reviewed and approved analyses and goes on to point out that "backfit rule" was applied because the staff believed the sites were not in compliance with regulations even though they had approved the analysis.

How is a licensee who has an NRC approved or acceptable analysis supposed to know that their analysis is no longer acceptable?

The RIS needs more clarification with regard to individual plant licensing bases if it is to be useful to licenses.

Some plants have installed degraded grid alarm systems and, at the staff request, included them in Unit Operating Technical Specifications.

Required operator actions related to degraded grid conditions are specified in the bases and procedures.

The RIS does not discuss this approach.

There are a number of plants that have URis related to this issue. Issuance of this RIS could be used by inspectors to close the URis to violations without regard to plant specific licensing bases, resulting in regulation by inspection

.. Proposed Resolution ID Section, Page, Line Number 5 Ref."Summary of Issues", pg. 6, Item 1. "Degraded Voltage Relaying Design Calculations", Line 5. Ref."Summaryof Issues", pg. 6, Item 1. "Degraded Voltage Relaying Design Calculations", Line 7. Comments on Draft NRC Regulatory Issue Summary 2011-XX, "Adequacy of Station Electric Distribution System Voltages" Docket 10 NRC-2011-0013 Comment Proposed Resolution The RIS states "The Class 1 E buses should separate from the Remove or clarify this statement since offsite power system within a few seconds if an accident occurs proper offsite system design and coincident with sustained degraded voltage conditions." operation renders such simultaneous postulated events as incredible.

GDC 17 describes the requirements for onsite and offsite power systems. One of its requirements is that they each provide sufficient capacity and capability to mitigate postulated events. The events are described in Chapter 15 "Accident Analysis".

These analyses assume Loss of Offsite Power simultaneous with the event. They do not require assuming degraded grid voltage condition prior to an event occurring.

In addition because of FERC and NERC requirements for voltage control, the likelihood of a chapter 15 accident occurring concurrent with a serious degraded grid voltage condition is not believed to be credible.

The RIS states "During normal plant operation, the Class 1 E Transmission Operators should be safety related buses should automatically separate from the allowed time to correct the degraded power supply within a short interval (typically less than 60 voltage condition while Plant Operators seconds) if sustained degraded voltage conditions are monitor the safety bus voltages for detected." adequate voltage. During normal plant operation (i.e. non LOCA), the degraded grid relay settings may be overly conservative.

Therefore automatic separation from the preferred power supply may not be desired.

Comments on Draft NRC Regulatory Issue Summary 2011-XX, "Adequacy of Station Electric Distribution System Voltages" 10 Section, Page, Line Number 7 Summary of Issues, DVR Setting Design Calculations, pg. 6 -7. Beginning at the bottom of page 6. 8 Ref. Summary of Issues, Last paragraph of "DVR Setting Design Calculations", PQ. 7. 9 Summary of Issues, Guidelines for voltage drop calculations, item (f) pg.8 Docket 10 NRC-2011-0013 Comment The RIS states "In this manner, the DVR ensures adequate operational (starting and running) voltage to all safety related equipment, independent of voltage contrOlling equipment external to the plant safety related electrical distribution system. For the purposes of this calculation, no credit should be taken for voltage controlling equipment external to the Class 1 E distribution system such as automatic load tap changers and capacitor banks." This statement needs to be clarified.

The discussion on time delays does not provide adequate criteria for time delay selections.

After paragraph (f) the RIS leaves out the guidance in GL 79-36 concerning minimum expected values (item 6 of enclosure

2) was omitted from the RIS guidance.

Proposed Resolution This statement needs to be clarified to allow reasonable assumptions for the status of equipment external to the Class 1 E distribution system. For example it is unclear how to perform motor starting calculations without taking credit for some Non 1 E voltage controlling equipment.

Additionally, normal Transmission grid switching to prepare for the next contingency to maintain minimum expected transmission system voltages should be allowed. Clarify. Add item 6 of enclosure 2 in GL 79-36 to the RIS.