ML19323A028
| ML19323A028 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 04/04/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Kemper J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| NUDOCS 8004110063 | |
| Download: ML19323A028 (1) | |
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4 UNITED STATES
[
~j, NUCLEAR REGULATORY COMMISSION O
j REGION I 631 PARK AVENUE
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KING OF PRUSSIA, PENNSYLVANIA 19406 Docket Nos. 50-352 50-353 Philadelphia Electric Company ATTN:
Mr. John S. Kemper Vice President Engineering and Research 2301 Market Street Philadelphia, Pennsylvania 19101 Gentlemen:
The enclosed IE Bulletin No. 80-07, "BWR Jet Pump Assembly Failure," is forwarded to you for information.
No written response is required.
If you desire additional.information regarding this matter, please contact this office.
Sincerely, W
Boyce H. Grier
/ M irector
Enclosures:
1.
IE Bulletin No. 80-07 with Attachments 2.
List of Recently Issued IE Bulletins CONTACT:
D. L. Caphton (215-337-5254) cc w/encis:
V. S. Boyer, Senior Vice President, Nuclear Power i
1 6004110o63
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SSINS No.:
6820 Accession No.
UNITED STATES 8002280648 NUCLEAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 l
Date:
April 4, 1980 i
Page 1 of 4 I
l BWR JET PUMP ASSEMBLY FAILURE 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 j
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 T.S., an orderly plant shutdown was begun to j
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 />.
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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 j
turbine, (3) indicated total core flow increased from 97.6 to 104.7 x 10 t
lb./hr., (4)coreplatedifferentialpressuredecreasedfrom16.1to33.8 psid.,and(5)Brecirculationloopflowincreasedfrom49to54x10 gpm j
while A recirculation loop flow remained at 49 x 10 gpm.
These changes were j
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 i
pump No. 13 was determined.
t 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 j
diameter of the bolt thread area. Failure of the beam assembly resulted in l
l pump decoupling at the diffuser connection.
Subsequent insitu ultrasonic l
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 l
of crack depth ranged from 6 to 20 mils. A sketch of the typical jet pump assembly is shown in Figures 1 and
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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 p
hh No. of s'
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