ML12348A394

NRC Bulletin 2012-01: Design Vulnerability in Electric Power System - Supplemental Response

ML12348A394
Person / Time
Site:	Nine Mile Point
Issue date:	12/07/2012
From:	Philippon M Constellation Energy Nuclear Group, EDF Group, Nine Mile Point
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BL-12-001
Download: ML12348A394 (6)

Text

Michel A. Philippon P.O. Box 63 Plant General Manager Lycoming, New York 13093 315.349.5205 315.349.1321 Fax CENGO.

a joint venture of Constellation eF wEnergy,'0 NINE MILE POINT NUCLEAR STATION December 7, 2012 U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTENTION: Document Control Desk

SUBJECT:

Nine Mile Point Nuclear Station Unit Nos. 1 and 2; Docket Nos. 50-220 and 50-410 NRC Bulletin 2012-01: Design Vulnerability in Electric Power System -

Supplemental Response

REFERENCE:

(a) Letter from M. A. Philippon (NMPNS) to Document Control Desk (NRC), dated October 25, 2012, NRC Bulletin 2012-01: Design Vulnerability in Electric Power System By letter dated October 25, 2012 (Reference a), Nine Mile Point Nuclear Station, LLC (NMPNS) provided the response to NRC Bulletin 2012-01 for Nine Mile Point Unit I and Unit 2 (NMP1 and NMP2). In that response, NMPNS noted that plant-specific electrical analyses of the offsite circuits for an open phase fault on the 115-kV offsite power system, with and without a ground fault, were in progress, and that the consequences of such an event and the plant response would be submitted by December 7, 2012. NMPNS hereby submits a summary of the results of the completed plant-specific electrical analyses in Attachments 1 and 2 for NMP 1 and NMP2, respectively.

This letter contains no new regulatory commitments. Should you have any questions regarding the information in this submittal, please contact John J. Dosa, Director Licensing, at (315) 349-5219.

Very truly yours, AV~?

Document Control Desk December 7, 2012 Page 2 STATE OF NEW YORK

TO WIT:

COUNTY OF OSWEGO I, Michel A. Philippon, being duly sworn, state that I am the Nine Mile Point Plant General Manager, and that I am duly authorized to execute and file this supplemental response on behalf of Nine Mile Point Nuclear Station, LLC. To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, they are based upon information provided by other Nine Mile Point employees and/or consultants. Such information has been reviewed in accordance with company practice and I believe it to be reliable.

Subscribed and sworn byfpre me, a 1ýotary P blic in and for the State of New York and County of 6tO ()e ~ , this 11 day of Cf/X; , 2012.

WITNESS my Hand and Notarial Seal:

I Notary fublic TONYA L jONES My Commission Expires: Notary Pubitc in the State of New Yo0 k CoswueontyExReg.

M Comriv No. 01 .54

.-,?oI4 My n Expires/I-,ti/-i° Date MAP/DEV Attachments: 1. Nine Mile Point Unit 1, NRC Bulletin 2012-01 Supplemental Response

2. Nine Mile Point Unit 2, NRC Bulletin 2012-01 Supplemental Response cc: Regional Administrator, Region I, NRC Project Manager, NRC Resident Inspector, NRC

ATTACHMENT 1 NINE MILE POINT UNIT 1 NRC BULLETIN 2012-01 SUPPLEMENTAL RESPONSE Nine Mile Point Nuclear Station, LLC December 7, 2012

ATTACHMENT 1 NINE MILE POINT UNIT 1 NRC BULLETIN 2012-01 SUPPLEMENTAL RESPONSE By letter dated October 25, 2012, Nine Mile Point Nuclear Station, LLC (NMPNS) provided the response to NRC Bulletin 2012-01 for Nine Mile Point Unit 1 (NMP1). In the response for Bulletin Items 1, 1.b, and 1.c, NMPNS noted that NMP1 plant-specific electrical analyses of the offsite circuits for an open phase fault on the 115-kV offsite power system, with and without a ground fault, were in progress, and that the consequences of such an event and the plant response would be submitted by December 7, 2012.

The following summarizes the results of the completed electrical analyses for NMP1.

A preliminary electrical analysis of the offsite circuits for an open phase on the 11 5-kV system with and without a high impedance ground has been completed using the Electro Magnetic Transient Program (EMTP-RV). EMTP-RV is professional software for simulation and analysis of transients in electrical power systems. The analysis included a variety of loading conditions ranging from transformer maximum loading to no load, along with grounding or no grounding of the open phase. An evaluation of the analysis results indicates that the amount of voltage imbalance between the phases is a function of the loading and whether or not the open phase condition introduces another ground on the auxiliary system. Also, the degree of voltage imbalance is significantly increased if the open phase condition is accompanied by a ground on the open terminal on the service transformer. The evaluation indicates that the existing undervoltage and degraded voltage relay systems at NMPI will not detect a number of open phase conditions, particularly under light load conditions.

As previously noted in the October 25, 2012 NMPNS letter, the NMP1 undervoltage and degraded voltage relay systems were not specifically designed to detect an open phase of a three phase system.

Detection of a single open phase condition is beyond the approved design and licensing basis of the plant.

Compensatory actions taken by NMPNS for NMPl were previously described in Attachment 1 of the October 25, 2012 NMPNS letter.

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ATTACHMENT 2 NINE MILE POINT UNIT 2 NRC BULLETIN 2012-01 SUPPLEMENTAL RESPONSE Nine Mile Point Nuclear Station, LLC December 7, 2012

ATTACHMENT 2 NINE MILE POINT UNIT 2 NRC BULLETIN 2012-01 SUPPLEMENTAL RESPONSE By letter dated October 25, 2012, Nine Mile Point Nuclear Station, LLC (NMPNS) provided the response to NRC Bulletin 2012-01 for Nine Mile Point Unit 2 (NMP2). In the response for Bulletin Items 1, 1.b, and 1.c, NMPNS noted that NMP2 plant-specific electrical analyses of the offsite circuits for an open phase fault on the 115-kV offsite power system, with and without a ground fault, were in progress, and that the consequences of such an event and the plant response would be submitted by December 7, 2012.

The following summarizes the results of the completed electrical analysis for NMP2.

A preliminary electrical analysis of the offsite circuits for an open phase on the 11 5-kV system with and without a high impedance ground has been completed using the Electro Magnetic Transient Program (EMTP-RV). EMTP-RV is professional software for simulation and analysis of transients in electrical power systems. The analysis included a variety of loading conditions ranging from transformer maximum loading to no load, along with grounding or no grounding of the open phase. An evaluation of the analysis results indicates that the amount of voltage imbalance between the phases is a function of the loading and whether or not the open phase condition introduces another ground on the auxiliary system. Also, the degree of voltage imbalance is significantly increased if the open phase condition is accompanied by a ground on the open terminal on the service transformer. The evaluation indicates that the existing undervoltage and degraded voltage relay systems at NMP2 will not detect a number of open phase conditions, particularly under light load conditions.

As previously noted in the October 25, 2012 NMPNS letter, the NMP2 undervoltage and degraded voltage relay systems were not specifically designed to detect an open phase of a three phase system.

Detection of a single open phase condition is beyond the approved design and licensing basis of the plant.

Compensatory actions taken by NMPNS for NMP2 were previously described in Attachment 2 of the October 25, 2012 NMPNS letter.

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