ML19344E125
| ML19344E125 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 07/23/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Koester G KANSAS GAS & ELECTRIC CO. |
| References | |
| NUDOCS 8008260672 | |
| Download: ML19344E125 (1) | |
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NUCLEAR REGULATORY COMMISSION UNITED STATES
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REGloN IV o
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611 RYAN PLAZA DRIVE, SulTE 1000 3*
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July-23, 1980
'In Reply Refer To:
RIV Docket No.
STN 50-482/IE Circular No. 80-17 Kansas Gas & Electric Co.
Attn:
Mr. Glenn L. Koester Vice President-Operations Post Office Box 208 Wichita, Kansas 67201 Gentlemen:
The enclosed IE Circular No. 80-17, is forwarded to you for information.
If there are any questions related to your understanding of the suggested i
actions, please contact this office.
I Sincerely, C,
'I Karl V. Seyfrit Director
/
Enclosures:
1.
IE Circular No. 80-17 2.
List of Recently Issued IE Circulars cc:
r/ enclosures Messrs. Nicholas A. Petrick, SNUPPS D. T. McPhee, Kansas City Power and Light Company Gerald Charnoff, Shaw, Pirtman, Potts & Trowbridge E. W. Creel, Kansas Gas and Electric Company 8008260672 l
t SSINS #6830 Accession No.:
UNITED STATES 8005050065 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Circular No. 80-17 Date: July 23, 1980 j
Page i of 2 FUEL PIN DAMAGE DUE TO WATER JET FROM BAFFLE PLATE CORNER Description of Circumstances:
)
On May 8, 1980, Portland General Electric submitted a Licensee Event Report No. 344/80-06,.concerning the April, 1980 discovery of failure of a fuel pin in each of two assemblies <during the past operating cycle. The LER stated that each of the fuel pins was located adjacent to a joint in the core baffle, and that the failures had resulted from tube vibration resulting from water i
jet impingement on the fuel pin.
This general type of damage has been experienced previously. Threw damaged fuel pins were found in 1971-72 at a non-domestic power plant.
Subsequently, j
one failed pin was found in 1973 and again in 1975 at non-domestic plants.
In 1975, one fuel pin failed at Point Beach. These six fuel pin failures involved bypass flow through gaps in the inside corner of the baffle (the fuel " sees" a i
90* angle, i.e., the edge of a box as seen from inside the box).
The baffle joints in these plants had not been peened prior to initial core loading.
)
Joints were peened following discovery of the failures, and no subsequent damage has been observed near the joints where the above failures were discovered.
More recently, in July 1979 fuel pin damage was detected in ten fuel assemblies at the Swedish Plant, Ringhals Unit 2.
In November, 1979 fuel pin damage was reported at the KO-RI Unit 1 in Korea on two fuel assemblies. Most recently in April, 1980 fuel pin failures were discovered in two assemblies at the end of Cycle 2 in Trojan.
In all three of the above recent instances, the failures were encountered in assemblies which had been associated with center injection points (the fuel." sees" a 270* angle, i.e.,
the edge of a box as seen from outside the box).
In addition in all three, the core support struc-tures utilized a baffle plate design with a reduced number of edge to edge bolts on adjoining baffles.
1 An ultimate fix of the baffle joint problem is to peen the entire joint with a
" flat land" peening technique to reduce the gap between baffle segments.
Because of scheduling concerns, this was not accomplished at Trojan during the recent outage. - Instead, PGE decided to install stainless steet pins adjacent to the two baffle joints of concern, and delay further peening efforts until the next refueling outage.
High velocity coolant cross flow (" jetting") through the gaps of the core baffle joints can result _ in damage to only a very limited number (usually 1 or
- 2) fuel pins, and only at certain discrete elevations on those pins.
Since 4
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IE Circular No. 80-17 Date:
July 23, 1980 Page 2 of 2 there is no mechanism for propagation of the failures to adjacent pins, these failures are not viewed as a significant safety concern.
However, in order to keep fuel failures and resulting primary coolant activity levels as low as possible, we recommend the following actions.
Recommended Actions for PWR Construction Permit Holders and PWR Licensees:
1.
Determine core locations that might be subject to water jet impingement upon fuel pins that could potentially be damaged by fretting.
2.
(Licensees only). Examine fuel pins that vere discharged from those locations, or are now at those locations (during the next refueling outage).
3.
Take appropriate actions to correct / prevent occurrence of this problem.
Although this problem has appeared only in certain Westinghouse PWRs, this Circular is being distributed to all PWRs since there may be other designs where the "as installed" core baffle may have plant specific features which could contribute to similar failures.
No written response to this Circular is required.
If you desire additional information regarding this matter, contact the Director of the appropriate NRC Regional Office.