ML19323A026
| ML19323A026 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/04/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| NUDOCS 8004110054 | |
| Download: ML19323A026 (1) | |
Text
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D UNITED STATES 8
N NUCLEAR REGULATORY COMMISSION O
E REGION I 0,
631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA 19406 Docket No. 50-245 Northeast Nuclear Energy Company ATTN:
Mr. W. G. Counsil Vice President - Nuclear Engineering and Operations P. O. Box 270 Hartford, Connecticut 06101 Gentlemen:
The enclosed IE Bulletin No. 80-07, "BWR Jet Pump Assembly Failure," is for-warded to you for action. A written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely,
/
/
Boyce H. Grier Director
Enclosures:
1.
IE Bulletin No. 80-07 with Attachments 2.
List of Recently Issued IE Bulletins CONTACT:
D. L. Caphton (215-337-5254) l cc w/encls:
l J. F. Opeka, Station Superintendent D. G. Diedrick, Manager of Quality Assurance J. R. Himmelwright, Licensing Safeguards Engineer W
8 0 01110 06 Q
l SSINS No.:
6820 Accession No.:
UNITED STATES 8002280648 l
NUCIIAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Bulletin No. 80-07 l
Date: April 4, 1980 i
Page 1 of 4 BWR JET PUMP ASSEMBLY FAILURE l
Description of Circumstances:
1 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 I
parameters during the event indicated an individual jet pump failure had l
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 />.
l The plant parameter changes reported by the licensee were (1) generator j
electrical output decreased from 539 to 511 MW electrical, (2) core thermal j
power decreased as indicated by decreased APRM readings and steam flow tg the l
turbine, (3) indicated total core flow increased from 97.6 to 104.7 x 10 lb./hr., (4) core plate differential pressure decreased from 16.1 to psid.,and(5)Brecirculationloopflowincreasedfrom49to54x10}3.8 gpm l
4 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 l
pump operability surveillance was performed, and an apparent failure of jet pump No. 13 was determined.
i Following vessel head removal and defueling, TV camera and visual inspections l
l
(
of the jet pumps and vessel annulus revealed the hold-down bea:n assembly of i
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 l'
assembly is shown in Figures 1 and 2.
On March 15-16, 1980, insitu ultrasonic I
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 l
Dresden.
Entire document Previously On March 28, 1980, Boston Edison reported entered into system under:
re ealed crack indications in three (3) h p
h e.,
No. of s-
.