ML19309D625
| ML19309D625 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 04/07/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 8004110034 | |
| Download: ML19309D625 (1) | |
Text
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9'o UNITED STATES 4,
NUCLEAR REGULATORY COMMISSION MC
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799 HOOSEVELT HOAD g,
f GLEN ELLYN,ILUNOIS 60137 Docket No. 50-155 7
Consumers Power Company ATTN:
Mr. R. B. DeWitt Vice President Nuclear Operations 212 West Michigan Avenue Jackson, MI 49201 Gentlemen:
The enclosed Bulletin 80-07 is torwarded to you for action. A written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, a1h $
James G. Kepp er Directar
Enclosure:
IE Bulletin No. 80-07 cc w/ encl:
Mr. D. P. Hof fman, Nuclear Licensing Administrator Mr. C. J. liartman, Plant Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Ronald Callen, Michigan Public Service Commission 8 0 04tt 0 c e?$
I SSINS No.:
6820 Accession No.:
UNITED STATES 800228J648 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEME.VT WASHINGTON, D.C.
20555 i
IE Bulletin 43 80-07 Date:
April 4, 1980 Page 1 of 4 BWR JET PUMP ASSEMBLY FAILURE l
Description of Circumstances:
On February 2,1980, Commonwealth Edison Company (CECO) reported that a jet pump failed in Dresden Unit 3 while operating at about 67 percent of full power in a coastdown mode to a refueling shutdown.
Observed changes in plant parameters during the event indicated an individual jet pump failure had l
occurred.
In accordance with l'.S., an orderly plant shutdown was begun to bring the unit to cold shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The plant parameter changes reported by the licensee were (1) generator electrical output decreased from 539 to 511 MW electrical, (2) core thermal power decreased as indicated by decreased APRM readings and steam flow tg the turbine, (3) indicated total core flow increased from 97.6 to 104.7 x 10 lb./hr., (4)coreplatedifferentialpressuredecreasedfrom16.1to33.8 psid.,and(5)Brecirculationloopficwincreasedfrom49to54x10 gpm while A recirculation loop flow remained at 49 x 10 gpm.
These changes were readily observed by the operator in the control room and it was postulated that a jet pump had failed.
Individual jet pump readings were taken, the jet pump operability surveillance was performed, and an apparent failure of jet pump No. 13 was determined.
Following vessel head removal and defueling, TV camera and visual inspections of the jet pumps and vessel annulus revealed the hold-down beam assembly of the suspect jet pump had broken across its ligament sections at the mean diameter of the bolt thread area.
Failure of the beam assembly resulted in pump decoupling at the diffuser connection.
Subsequent insitu ultrasonic examination of all other jet pump hold-down beams, using a special UT technique developed by General Electric (GE), revealed ultrasonic indications of cracking at the same location in 6 of the remaining 19 beams examined.
Initial estimates of crack depth ranged from 6 to 20 mils.
A sketch of the typical jet pump assembly is shown in Figures 1 and 2.
On March 15-16, 1980, insitu ultrasonic jet pump hold-down beam assemblies at Qua refueling).
One beam was found to contai in excess of 100 mils depth in the same 1 DUPLICATE DOCUMENT Dresden.
Entire document previously On March 28, 1980, Boston Edison reported entered into system under.
revea d crack indications in three (3) h g
h No. of es-
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