ML20084S547
| ML20084S547 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 08/27/1971 |
| From: | Haueter R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Morris P, Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084S549 | List: |
| References | |
| NUDOCS 8306170103 | |
| Download: ML20084S547 (2) | |
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omoi. 4,.. coa. m 7 an.o sso August 27, 1971 Dr. Peter A. fiorris, Director Re: Docket No 50-255 Divisicn of Reactor Licensing License No DPR-20 US Atcraic Energy Cot: mission Washingten, DC 20545
Dear Dr. Morris:
Attention:
Mr. D. J. Skovholt This letter is written to apprise you of a recent incident involving the mechanical seal unit of a primary coolant pump at this facility.
At the time the incident occurred, the plant was in a hot abutdown conditic,n with primary coolant system at refueling boron 0
concentration, 532 F and 2100 psia. The four primary coolant pumps were in cperation and preparations underway to dilute the boron and brin 6 the reactor critical for low power operation.
A supervisor making a visual check of the primary coolant system ut, 2100 on August 19, 1971, observed water lying on the "A" primary coolant pump cover. Subsequent investigation revealed that thecourcewasa3/8inchlongcrackinthepipevallatthetoeof theveldbetweenthesealhousingandthe3/4inchpressuretapto the lower seal cavity. The observed leakage was estimated to be one pint per minute.
A routine primary system inventory check was initiated and the system leak rate determined to be 0.25 gpm as compared to an earlier check of 0.032 gym. At 0040 on August 20, 1971, the cooldown and deprescurination (of the primary coolant system) was initiated te allow repair of the leak.
The seal unit was removed from the "A" primary coolant pump and replaced with a spare unit.
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2 Dr, Peter A.. rris US Atomic Energy Comission August 27, 1971 CAUSE OF INCIDI2iT The cause of the failure was determined to be metal fatigue due to inTroper cupport and flexure o'f the 3/4 inch schedule 60 type 304 GS pipe and 11ange assembly, resultin6 in a cracked pipe. TMs particular pipe connection has several valves and a filter unit installed approximately three feet away from the seal causing the I
welded connection to be heavily strecaed if the pipe is allowed to flex to even a minor degree.
CORinyJfIVE ACTION PLANNED Additional nupports will be installed to reduce the vibration and to minimize the ctreco at the welded connections. Also, much of the hee.vy spparatus will be mounted on the concrete wall and connected with steel tubing. These support modifications will be accomplished on all four of the primary coolant pumps.
Yours very truly, C: L f u e:ct IMH/RLU/ tion Robert L. Haueter Electric Production Superintendent - Nuclear CC: BHGrior USAEC Cocpliance, COO r
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