ML20141G243

Provides Status Update on Corrective Actions Re Identified Discrepancy in Emergency Operating Procedures (EOP) FR-C.1 & FR-C-2

ML20141G243
Person / Time
Site:	Maine Yankee
Issue date:	04/11/1997
From:	Hebert J Maine Yankee
To:	Russell W NRC (Affiliation Not Assigned)
References
JRH-97-74, MN-96-47, NUDOCS 9705220232
Download: ML20141G243 (3)

Text

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. MaineVankee REllABLE ELECTRICITY SINC 51972 329 BATH ROAD + BRUNSWICK, MAINE 04011 = (207) 798-4100 i

April 11,1996 l MN-96-47 JRH-96-74 l l

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l Mr. William T. Russell l Director, Office of Nuclear Reactor Regulation )

, U.S. Nuclear Regulatory Commission Mail Stop 12 G18 ,

Washington, DC 20555-0001 l

References:

(a) License No. DPR-36 (Docket No. 50-309) ,

(b) Letter, MYAPCo to Mr. Thomas T. Martin, USNRC, " Notification Under 10CFR 50.9," dated March 4,1996 (MN-96-25).

(c) Maine Yankee Emergency Operating Procedure Generation Package dated l March 18,1986 (MN-86-42). l (d) Letter, MYAPCo to Mr. William T. Russell, USNRC, Discrepancy in EOP j l Verification Analysis dated March 28,1996 (MN-96-38).

Subject:

Status Update Associated with Discrepancy in EOP Verification Analyses Gentlemen:

l [ 80 This letter describes the status of our progress associated with the corrective actions concerning the identified discrepancy in the EOP Verification Analyses as discussed in Reference (d). The i following describes the progress and initiatives taken since our last correspondence.

.A comprehensive close-out plan has been developed and approved by the Plant Operation Review Committee (PORC) to ensure pertinent aspects of this issue are being adequately addressed.

Further changes to the Emergency Operating Procedures (FR-C.1 and FR-C-2) have been  ;

incorporated to provide additional steam dumping capacity by utilizing the steam driven auxiliary feed pump in addition to simultaneously dumping steam via the auxiliary steam system and the atmospheric steam dump valve. The combined benefit of these steam removal capabilities is currently being calculated. These changes to the Emergency Operating Procedures have been thoroughly evaluated to ensure the changes do not create any other adverse affects.

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MaineYankee U.S. NUCLEAR REGULATORY COMMISSION MN-96-47 Attn: Mr. William T. Russell Page Two l

We have identified several potential interim corrective actions which will increase the steam relieving and/or heat removal capability. These potential corrective actions are being thoroughly evaluated to ensure that they do not create other unacceptable adverse affects.

In addition to these interim corrective measures, Maine Yankee is continuing to evaluate other long term corrective actions. We plan to finalize these long term corrective action plans and implementation schedule by July 31,1996.

We have performed a systematic review of the assumptions utilized in the EOP verification analysis to determine if these assumptions are valid for the current EOPs and plant configuration.

Based on the preliminary results, we have identified one currently incorrect assumption and one other assumption which was corrected in 1987. The following describes these incorrect assumptions ,

and there associated impacts. l J. The steam generator tube rupture (SGTR) EOP Verification Analysis-(Rev.1) assumes that the affected steam generator, secondary side, can be isolated within 13 minutes from the time of reactor trip. This time is reasonable for the realistic steam generator tube rupture event. However, it may not be reasonable to assume that the manual remote operator actions can be accomplished within 13 minutes during an event in which the main condenser is unavailable, such as during a loss of off-site power. During this postulated event, we expect that the S/G code safety valves would be lifting. The drains associated with the safety valves vent to the same area in which these manual remote operator actions take place. It is possible that these environmental conditions could delay operator actions. Under these postulated circumstances we believe additional time for operator actions would be more appropriate and is being evaluated by analysis.

We are in the process of re-perfcnning the S/G tube n:pture analysis with increased j isolation time assumptions. The preliminary results for this re-analysis show that the off-site dose projection is not significantly affected. j

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4 It should be noted that the Maine Yankee EOPs direct closing the reactor coolant l system loop isolation valves after 45 minutes. The original analysis as well as the re-analysis effort conservatively do not take credit for this action.

Operations department has put in place interim actions for isolating the affected steam generator during the postulated SGTR without the main condenser. All l operators have been made aware of the issue and additional training is planned during the next requalifications training block.

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i MaineYankee ,

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U.S. NUCLEAR REGULATORY COMMISSION MN-96-47 l Attn: Mr. William T. Russell Page Three <

II. A previously identified assumption for the Inadequate Core Cooling condition assumed that the atmospheric steam dump valve could be manually opened if operation from the l Main Control Board (MCB) became unavailable. The original Emergency Operating  ;

Procedures (FR-C.1 and FR-C.2) directed manual local operation of this valve. It was i subsequently determined that this valve was not equipped with a local handwheel. This  ;

procedural condition was revised in 1987 to direct atmospheric steam dump valve operation from the Alternate Shutdown panel if MCB operation becomes unavailable.

l The plant root cause evaluation has been chanered and is underway. The investigation is in the ,

i preliminary stages of conducting interviews and collecting documents, We expect this effort to be i

complete by May 15,1996.

We will continue to keep you informed on our progress. We plan to provide an additional status i report by May 15,1996.

Sincerely, ,

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James R. Hebert, Manager Licensing & Engineering Support l 1

c: Document Control Desk  !

Mr. Thomas T. Martin

! ' Mr. J. T. Yerokun Mr. E. H. Trottier Mr. Patrick J. Dostie

~ Mr. Uldis Vanags I I

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