ML19309D633
| ML19309D633 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 04/07/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Gerstner W ILLINOIS POWER CO. |
| References | |
| NUDOCS 8004110042 | |
| Download: ML19309D633 (1) | |
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UNITED STATES 8*
'o NUCLEAR HEGULATORY COMMISSION 7
REGION 111 o
799 ROOSEVELT ROAD Yg b'
GL E N E LLYN, ILLINOIS 6o137
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Docket No. 50-461 NR7 y,,,
Docket No. 50-462 Illinois Power Company ATTN:
Mr. W. C. Gerstner Executive Vice President 500 South 27th Street Decatur, IL 62525 Gertlemen:
The enclosed Bulletin 80-07 is forwarded to you for information. No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely,
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gJames G. Keppler Director
Enclosure:
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Central Files 3
Director, NRR/DPH Director, NRR/ DOR PDR l
Local PDR l
NSIC l
TIC Mr. Dean Hansell, Office of Assistant Attorney General a
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SSINS No.:
6820 Accession No.:
UNITED STATES 8002280648 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTCN, D.C.
20555 i
IE Bulletin No. 80-07 Date:
April 4, 1980 Page 1 of 4 i
BWR JET PUMP ASSEMBLY FAILURE Description of Circumstances:
i 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 occurred.
In accordance with T.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 />.
5 The plant parameter changes reported by the licensee were (1) generat'or 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) B recirculation loop flow increased gpm whileArecirculationloopflowremainedat49x10{ rom 49to54x10 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.
1 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 I
Dresdet.
l Entire document previous 1y entered into system under:
l On March 28, 1980, Boston Edison reported re ca d crack indications in three (3) b g
h No. of es: