ML18038B678
| ML18038B678 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 04/19/1996 |
| From: | Salas P TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-95-002, IEB-95-2, NUDOCS 9604290204 | |
| Download: ML18038B678 (8) | |
Text
CATEGORY j.
REGULA Y INFORMATION DISTRIBUTIO
'SYSTEM (RIDS)
ACCESSION NBR:9604290204 DOC.DATE: 96/04/19 NOTARIZED: NO FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee AUTH.NAME AUTHOR AFFILIATION SALAS,P.
Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
DOCKET 05000260
SUBJECT:
Responds to NRC Bulletin 95-002, "Unexpected Clogging of RHR Pump Strainer While Operating in Suppression Pool Cooling Mode n
DISTRIBUTION CODE:
IE44D COPIES RECEIVED:LTR
(
ENCL 0 SIZE: S TITLE: NRC Bulletin 95-02 Unexpected Clogging of RHR Pump Strainer While NOTES:
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RECIPIENT ID CODE/NAME PD2-3-PD INTERNA NRR/DSSA/SCSB EXTERNAL: NRC PDR COPIES LTTR ENCL RECIPIENT ID CODE/NAME WILLIAMS,J.
NRR/DRPW/PD3-2 COPIES LTTR ENCL 0
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N NOTE TO ALL "RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE!
CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN 5D-5(EXT. 415-2083)
TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR' ENCL
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Tennessee Valley Authority. Post Office Box 2000. Decatur, Atabarna 35609 April 19, 1996 U.S. Nuclear Regulatory Commission ATT.:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of Tennessee Valley Authority Docket Nos.
50-260 BROWNS FERRY NUCLEAR PLANT (BFN)
NRC BULLETIN NO 95 02 I UNEXPECTED CLOGGING OF A RESIDUAL HEAT REMOVAL (RHR)
PUMP STRAINER WHILE OPERATING IN THE SUPPRESSION POOL COOLING MODE
[TAC M93877]
This letter provides TVA's notification of a completed commitment from the November 15, 1995, reply to the subject NRC Bulletin 95-02.
Specifically, in the reply, TVA indicated divers would be utilized to visually inspect the Unit 2 suppression pool including the Emergency Core Cooling System (ECCS),
RHR pump suction strainers, for material which could potentially block strainer suction during the Unit 2 Cycle 8
refueling outage.
- Also, TVA would issue a letter detailing the results of this inspection 10 days after they are completed and reviewed.
In the letter dated November 15,
- 1995, TVA stated that the Unit 2 Suppression Pool was cleaned and visually inspected during the Unit 2 Cycle 7 outage that took place in October of 1994.
As a result of findings during that inspection, TVA performed a
complete cleaning of the suppression pool removing any debris and buildtup of sludge that had accumulated during the previous operating cycle.
During the current operating cycle (Cycle 8),
TVA operated the RHR and Core Spray System pumps taking suction through ECCS suction strainers in excess of 178 hours0.00206 days <br />0.0494 hours <br />2.943122e-4 weeks <br />6.7729e-5 months <br /> without experiencing any strainer clogging problems.
9604290204 960419 PDR ADOCK 05000260 8
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U.S. Nuclear Regulatory Commission Page 2
April 19, 1996 It was agreed that no confirmatory test was to be performed prior to entering the Unit 2 Cycle 8 outage.
- However, TVA committed to use divers to visually inspect the suppression pool and ECCS ring header strainers.
The staff agreed with TVA's conclusions and on March 14, 1996, the, staff issued a
Safety Evaluation accepting TVA's proposed actions.
On March 27 and 28, and again on April 6, 1996, divers were utilized to visually inspect and video tape the Unit 2 Suppression Pool, including the ECCS ring header strainers, to determine the as found condition of the suppression pool and strainers.
'The results of the, inspection indicated that a small amount of fibrous materials was identified on the ECCS ring header strainers.
TVA conservatively estimated that the total area blocked from this material to be less than ten percent of the effective strainer area.
This amount of material is smaller than the 20 percent blockage identified during the Unit 2 Cycle 7 outage inspection.
TVA has performed a debris transport/settling analysis and found that up to 65 percent blockage of the four ECCS ri.ng header suction strainers is acceptable'ithout adversely affecting the net positive suction head requirements for the ECCS pumps.,
During the inspection, TVA found that the overall condition of the torus to be sound.
The water clarity was good and a
minimal amount of sediment was identified in the torus.
.Items found by, the divers were retrieved from the suppression pool floor and logged.
Examples included small pieces of masking
- tape, small pieces of paper, plastic tie wraps and some small pieces of wire.
These items were removed from the torus.
The material adhered to the ECCS suction strainers was also removed.
TVA evaluated the as-found condition of the suppression pool and the ECCS ring header strainers and determined that the suppression pool and the ECCS ring header strainers were in acceptable condition for Cycle 9 operation.
As such, the material found during this inspection is less than that which would adversely affect ECCS pump performance during a post-Loss of Coolant Accident condition.
Oi ii e%
U.S. Nuclear Regulatory Commission Page 3
April 19, 1996 This letter satisfies the commitment for the ten-day notification.
As previously stated, TVA will continue to participate in the General Electric Boiling Water Reactor Owners Group activities to i.dentify measures that should be considered for implementation at BFN.
There are no new commitments made in this letter. If you have
.any questions, please contact me at.
(205) 729 2636.
ce ly, ed Salas anager of Site Licensing Subscribed and sworn to before me on this ++K Day of o
1996.
eu ~
My commission expires
'Enclosure cc (Enclosure)
Mr. Mark S. Lesser, Branch Chief U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road
- Athens, Alabama 35611 Mr. J.
F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 1'1555 Rockville Pike Rockville, Maryland 20852
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