05000277/LER-1978-043, Forwards LER 78-043/03L-0

Forwards LER 78-043/03L-0

ML19289F138
Person / Time
Site:	Peach Bottom
Issue date:	11/17/1978
From:	Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19289F139	List: 05000277/LER-1978-043, Forwards LER 78-043/03L-0 05000277/LER-1978-043-03, /03L-0 on 781019:snubber 23HBS-38 Found W/Unacceptable Bleed Rates & Locking Velocities.Caused by Clogged Bleed Orifices & Low Ambient Temp During Tests. Safety-related Snubbers Tested,Repaired & Recalib
References
NUDOCS 7906040320
Download: ML19289F138 (3)

LER-1978-043, Forwards LER 78-043/03L-0

Event date:
Report date:
2771978043R00 - NRC Website

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PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET PHILADELPHIA PA,19101 (215) 841-4o00 November 17, 1978 Mr. Boyce H.

Grier, Director Office of Inspection and Enforcement Region I United States Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406

Dear Mr. Grier:

SUBJECT:

Licensee Event Report Narrative Description

Reference:

Docket Number 50-277 Report No:

LER 2-73-043/3L-0 Report Date:

November 17, 1978 Occurrence Date:

October 19, 1978 Facility:

Peach Botton Atomic Power Station R.D.

1, Delta, PA 17314 Technical Specification Reference:

Technical Specification 4.ll.D.1 states in part "All hydraulic snubbers..... shall be visually inspected.

The inspection shall include, but not necessarily be limited to, inspection of the hydraulic fluid reservoir, fluid connections, and linkage connections to the piping and anchor to verify snubber operability...

Technical Specification 4.11.D.4 states in part, "Once each refueling cycle, a representative sample of 10 hydraulic snubbers or approximately 10% of the hydraulic s r.u b b e r s, whichever is less, shall be functionally tested for operability including verification of proper piston movement, lock up and bleed.....

I 2236 092 b TI 7906040 3 3 o J

l

'Mr.

Boyce H.

Grier Page 2 November 17, 1978 LER 78-043/3L-0 Description of the Event:

During a routine snubber inspection per Tech Spec 4.ll.D.1, snubber 23 HBS-38 on the HPCI turbine exhaust line was found with an empty reservoir.

Subsequent functional testing showed this snubber had a bleed velocity of.088 inches per minute.

The minimum acceptable bleed rate is.125 inches per minute.

During functional testing of ten snubbers per Tech Spec 4.ll.D.4, two snubbers failed to meet the minimum bleed rate criteria and two snubbers failed to meet the minimum 14" per uinute locking velocity criteria.

Because of this all safety related snubbers were ftnetionally tested.

Of 145 snubbers, 41 had average locking velocities and 12 had average bleed rates which failed to meet the minimum acceptance criteria.

Consequences of Event:

Safety significance is minimal since the majority of snubbers would have operated properly.

In addition, manufacturer's inf orma tion indicates that snubber locking velocities are somewhat temperature sensitive because of oil viscosity.- Since locking velocities increase with increasing temperature, most snubbers which failed to meet the minimum locking velocity operability criteria would have operated properly under normal higher ambient temperature conditions in their installed locations.

Cause of Event

Low bleed velocities were caused by plugging of the small bleed orifices in the snubber valve blocks.

Apparently seal material'which entered the snubber oil during p revious maintenance contributed to the plugging.

Low locking velocities were caused by lower than normal ambient temperatures in the test area which caused a downward shift in the as found locking velocity data due to temperature sensitivity.

Corrective Action

All safety related snubbers were tested, cleaned and repaired as necessary, and recalibrated.

Action to Prevent Recurrence:

The locking velocity setpoint of all snubbers was increased from 1511 inches per minute for main steam relief valve downcomer snubbers and 10 1 1 inches per minute for all other snubbers to 20 1 2 inches per minute in order to avoid exceeding the minimum locking velocity criteria in the future.

In addition, a representative sample of 10 snubbers will be retested

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2236 093

r Mr. Boyce H.

Grier Page 3 November 17, 1978 LER 78-043/3L-0 during the present operating cycle to verify that no additional bleed rate problems have developed.

Yours truly, G^

/

lM.

V

!Y Cooney Suyerintendent veneration Division-Nuclear Attachment ec:

Director, NRC - Office of Inspection and Enforcement Mr. Norman M.

Heller, NRC - Office of Management &

Program Analysis 2236 094