ML17262A602

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Special Rept:On 910903,svc Water Leak Inside Containment Sump a Pump Identified.Abnormal Procedure AP-SW.1, Svc Water Leak, Entered.Work Order Package Prepared to Identify & Repair Svc Water Leak
ML17262A602
Person / Time
Site: Ginna Constellation icon.png
Issue date: 09/17/1991
From: Mecredy R
ROCHESTER GAS & ELECTRIC CORP.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9109250235
Download: ML17262A602 (5)


Text

ACCELERATED DOOIBUTION DEMONS'iA.TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9109250235 DOC.DATE: 91/09/17 NOTARIZED-NO DOCKET FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G

05000244 AUTH.NAME AUTHOR AFFILIATION MECREDY,R.C.

Rochester Gas

& Electric Corp.

RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Special rept:on 910903,svc water leak inside containment sump A pump identified. Abnormal Procedure AP-SW.1, "Svc Water'eak,"

entered. Work order package prepared to identify

& repair svc water leak.

DISTRIBUTION CODE:

IE22D COPIES RECEIVED:LTR 4 ENCL J SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Tncident Rpt, etc.

NOTES:License Exp date in accordance with 10CFR2,2.109(9/19/72).

/

05000244 RECIPIENT ID CODE/NAME PD1-3 LA JOHNSON,A INTERNAL: ACNW AEOD/DSP/TPAB NRR/DET/ECMB 9H NRR/DLPQ/LHFB10 NRR/DOEA/OEAB NRR/DST/SELB 8D B8D1 G

02 RGN1 FILE 01 EXTERNAL: EG&G BRYCE,J.H NRC PDR NSIC POOREgW COPIES LTTR ENCL 1

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1 RECIPIENT ID CODE/NAME PD1-3 PD AEOD/DOA AEOD/ROAB/DSP NRR/DET/EMEB 7E NRR/DLPQ/LPEB10 NRR/DREP/PRPB11 NRR/DST/SICB8H3 NRR/DST/SRXB 8E RES/DSIR/EIB L ST LOBBY WARD NSIC MURPHY~ G A NUDOCS FULL TXT COPIES LTTR ENCL 1

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1 NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED:

LTTR 31 ENCL 31

aC net

~ wl a

loca ssasr ROCHESTER GAS AND ELECTRIC CORPORATION

~

89 EAST AVENUE, ROCHESTER N.Y. 14649-0001 ROBERT C. MECREDY Vice Presidenl Cinna Nuclear Producsion TELEPHONE AREA COOE 7 5 6 546'2700 September 17, 1991 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Subject:

Service Water Leak Inside Containment R.E.

Ginna Nuclear Power Plant Docket No. 50-244 In accordance with the requirements of IE Bulletin No. 80-24, (Prevention of Damage Due to Water Leakage Inside Containment),

the attached 14 Day Report is hereby submitted.

Very truly yours, Robert C. Mecred xc:

U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Ginna USNRC Senior Resident Inspector 910925023 910917 PDR ADDCt'5000244 PDR P(p~

iY

SERVICE WATER LEAK INSIDE CONTAINMENT PRE-%TENT PLANT CONDITIONS The plant was at approximately 974 steady state reactor power.

The Results and Test (R&T)

Group had completed Periodic Test procedure, PT-2.7 (Service Water System) at approximately 1451

EDST, September 3,

1991.

Containment (CNMT) Sump "A" Pump actuation was received at approximately 1626

EDST, September 3,

1991 and the actuation interval between the last two pump actuations was calculated to be approximately 199 hours0.0023 days <br />0.0553 hours <br />3.290344e-4 weeks <br />7.57195e-5 months <br />.

The CNMT Sump "A" is located at the bottom of the reactor vessel cavity and is the lowest elevation of the CNMT vessel.

DESCRIPTION OF EVENT On September 3,

1991 at approximately 2115 EDST, with the reactor at approximately 974 full power, the Control Room operators observed that the CNMT Sump "A" level had increased to about the halfway point to another sump pump actuation.

This indicated a significant decrease in the time between CNMT Sump "A"

pump actuations (estimated leakage of 10 gals/hr),

leading the Control Room operators to suspect some type of increased leakage inside of CNMT.

An investigation to determine the cause of leakage inside CNMT was immediately initiated.

Indications of a possible Reactor Coolant System leak were not present; no significant unexplainable increases or changes were observed on radiation monitors R-11 and R-12 (CNMT Air Particulate Monitor and CNMT Radioactive Gas Monitor, respectively),

the CNMT Dewpoint, the Reactor Coolant System

Leakage, or the CNMT Recirc Fan Cooler Dumps.

Based upon these indications, the Control Room operators suspected a

service water leak and entered Abnormal Procedure, AP-SW.1 (Service Water Leak).

As part of AP-SW.1, the CNMT Recirc Fan Coolers are isolated, one at a time, to determine if they are the service water leak path to CNMT.

When the "D"

CNMT Recirc Fan Service Water was

isolated, the leakage to CNMT Sump "A" was significantly reduced.

This confirmed a service water leak from the "D"

CNMT Recirc Fan Cooler or Motor Cooler.

The "D" CNMT Recirc Fan Cooler

and Motor Cooler were declared inoperable, isolated and held.

A Ginna Station Work Request or Trouble Report (WR/TR) was initiated (i.e.,

WR/TR ¹9101554) to repair the service water leak associated with the "D" CNMT Recirc Fan Motor Cooler.

The Control Room operators notified higher supervision, the Nuclear Regulatory Commission (NRC) and the NRC Resident Inspector of the event.

III.

CORRECTIVE ACTION A.

ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-E&BFZ NORMAL STATUS:

Work Order Package

¹9101554 was prepared to identify and repair the service water leak associated with the "D" CNMT Recirc Fan Motor Cooler, utilizing Emergency Maintenance procedure, EM-745 (Repair of Containment Recirculation Fan Motor Cooler Coil).

Visual inspection of the "D"

CNMT Recirc Fan Motor Cooler revealed a 1/4" rupture in the first row, ninth tube return "U" bend (a 5/8" diameter tube).

This "U"

bend had been previously repaired during the 1991 Refueling Outage.

The rupture was adjacent to the previous patch.

The previous patch was removed and a

new patch silver soldered into place covering both openings on 9/5/91.

The patch leaked upon pressurization and a replacement patch was applied on 9/6/91.

During the subsequent repressurization, a

pin hole leak (i.e.,

less than 1/8")

was identified in the second row, ninth tube return "U" bend.

This leak was also repaired by a silver soldered patch on 9/7/91.

The subsequent repressurization revealed a

leak at the brazed connection between the discharge header and discharge pipe.

This connection is on top of the cooling coil.

This leak was the result of stressing the connection during coupling disassembly while performing the first and second solder repairs.

This cracked connection was repaired by brazing on 9/8/91.

The cooler was subsequently repressurized (no indication of leakage was apparent) and returned to service.

ACTION TAKEN OR PLANNED TO PREV19FZ RECtJRR194CE:

As the underlying cause of the event was determined to be "U" bend tube thinning aggravated by pressure spikes during the performance of PT-2.7, the following actions to prevent recurrence have been taken or are planned:

0 The order for a

replacement CNMT Recirc Fan Motor Cooler has been expedited, and the cooler will be used as a spare, if required.

0 Replacement of all CNMT Recirc Fan Motor Coolers is planned for the 1992 Maintenance and Refueling Outage.

The RST Group will perform a review of PT-2.7 to assess if enhancement of the existing text would preclude future pressure spikes from occurring.

A review of appropriate Operating and Testing procedures will be performed to assess if enhancement of the existing text would preclude future pressure spikes from occurring.