ML19323J343
| ML19323J343 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 05/28/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Woolever E DUQUESNE LIGHT CO. |
| References | |
| NUDOCS 8006200042 | |
| Download: ML19323J343 (1) | |
Text
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UNITED STATES 8
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j REGION I 8
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KING OF PRUS$1A, PENNSYLVANIA 19406 May 28, 1980 Docket No. 50-412 Duquesne Light Company ATTN:
Mr. E. J. Woolever Vice President 435 Sixth Avenue Pittsburgh, Pennsylvania 15219 Gentlemen:
The enclosed IE Circular No. 80-13 " Grid Strap Damage in Westinghouse Fuel Assemblies," 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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Boyce H. Grier Director
Enclosures:
1.
IE Circular No. 80-13 with Attachment 2.
List of Recently Issued IE Circulars CONTACT:
D. L. Caphton (215-337-5262) cc w/encls:
R. J. Washabaugh, Quality Assurance Manager THIS DOCUMENT CONTAINS P00R QUAllTY PAGES 8006200692
u ENCLOSURE 1 SSINS No.: 6830 Accessions No.:
UNITED STATES 7910250495
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NUCLEAR' REGULATORY COMISSION
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WASHINGTON, D.C. 20555 4
IE Circular No. 80-13 I
Date:
May 28, 1980 Page 1 of 2 l
GRID STRAP DAMAGE IN WESTINGHOUSE FUEL ASSEMBLIES Description of Circumstances:
During the refueling o)eration at Salem Unit 1, it was noted by the licensee that some of the assem) lies that were removed had suffered grid strap mechanical damage.
This was reported to the NRC in LER 79-44.
Subsequent to this discovery all fuel assemblies were removed from the core for examination.
The degree of the damage to the grid straps was classified in three categories: small pieces missing (15 assemblies), grid material ripped and laid over (5 assemblies),
larger sections missing and fuel pins exposed (11 assemblies).
No damage to the fuel pins was observed.
A total of 31 assemblies suffered some grid damage.
The damage appeared to be the result of corner to corner interaction of the grid straps of diagonally adjacent fuel assemblies during the vertical loading and unloading movements.
No correlation of the damage to core location, grid strap elevation, or manufacturing and shipping batches has been identified.
The licensee and the fuel manufacturer established the following guidelines for reloading damaged assemblies: (1) those assemblies with full width pieces missing will not be reloaded for cycle 2, (2) those assemblies with deformed edges and those with small pieces missing will be reloaded with special pro-cedures to prevent further damage.
Salem Unit 1 is fueled with 17X17 Westinghouse assemblies.
Similar grid i
problems have occurred at other facilities fueled with 14X14 and 15X15 Westing-house assemblies; however, fewer assemblies were damaged in those instances.
Recommended Actions:
l All licensees using 14X14, 15X15, or 17X17 Westinghouse assemblies are advised to:
(1) Visually inspect grid straps of those fuel assemblies which are discharged i
from the core as well as those assemblias which are moved to the spent fuel pool for control rod replacement and are subsequently returned to the core.
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IE Circular No. 80-13 Date:
May 28, 1980 l
4 Page 2 of 2 l
(2) Review the fuel handling precautions recommended by Westinghouse at a i
meeting on May 25, 1979, with NRC and the licensee for Salem (Attachment 1).
Adopt those recommendations which are pertinent.
No written response to this Circular is required.
If you required additional information regardin NRC Regional Office.g these matters, contact the Director of the appropriate
Attachment:
Summary of Meeting Notice dated 5/30/79 i
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Attachment to IE Circular No. 80-13
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UNITED STATES 8
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Docket No. 50-272 LICENSEE:
PUBLIC SERVICE ELECTRIC & GAS COMPANY (PSE&G)
FACILITY:
SALEM UNIT NO. 1
SUBJECT:
SUW.ARY OF MEETING HELD ON MAY 25, 1979, TO DISCUSS DAMAGE OBSERVED TO FUEL GRID ASSEMBLIES DURING THE SALEM UNIT NO. 1 REFUELING OUTAGE On May 25, 1979, we met with representatives of Public Service Electric &
Gas Company (PSE&G) and Westinghouse to discuss the cause and extent of damage observed to the Salem Unit No.1 fuel grid assemblies during tte current refueling outage for cycle 2.
A list of attendees is enclosed.
Significant discussions are summarized below.
The licensee anif Westingh6use provided a detailed discussion of the da:. age observed to the Salem fuel grid assemblies during the cycle 2 refueling outage which comenced in April 1979.
Due to the indications
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. observed during the initial stages of the outage, the decision was made to unload all fuel assemblies from the core.
Of the fuel assemblies (193) inspected, 28 assemblies were determined to have varying degrees cf danage to one or more of the eight grid assemblies per fuel assembly.
The grid assemblies provide lateral support to the fuel rods.
In no case was dacage observed to the fuel rods themselves.
The grid assembly dar. age observed, which was generally located at the corners of the grid assemblies, was categorized as follows:
Category Tvpa of Damace N_o_._ of Grid Assemblies 1
small pieces missing 1S 2
grid material ripped 4
and laid over 3
Iarger sections missing and 9
fuel pins exposed O'
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Attachment to IE Circular No. 80-13 Meeting Summary for Salem Unit 1 -
Of the above, fuel assemblies with categories 1 and 2 damage were determined by the licensee to be acceptable-for use and will be reloaded for cycle 21 as a precautionary measure assemblies with category 3 damage will not be reloaded. The basis for this determination was that assemblies with category 1.and 2 damage can be used without any loss of function of the damaged grids.
Fuel assemblies With category 3 damage, however, no longer fully restrain all fuel rods in the manner provided for in the design. Their rease should be based on further analysis.
Of the data collected and the reload films reviewed, no pattern has been established for the observed damage.
Also, it has not been determined whether the damage ociurred during fuel insertion for cycle 1, or during removal or readjustments for cycle 2, or both.
It is believed that corner-to-corner interaction may have occurred between grid assemblies of adjacent fuel assemblies especially when diagonal fuel assemblics have been removed and sonne degree of lateral movement is possible.
Under these conditions the grid assemblies nuy have been aligned such that the corners interacted during vertical movement.
a total area of about 25in2 is involved.
Of the pieces missing (about 61), 2 up to about 5. fin 2 These pieces range from about.3fn Approximately 12in2 of material has been recovered from' the core or the fuel assemblies during the unloading of the core.
In addition, the core was inspected with a TV camera.
With regard to the potential for flow blockage from the missing material, Westinghouse indicated that if all the peices criginally missing were to be located such as to partially block the inlet nozzle area of the one fuel assembl, analyres similar to that described in Section 3.4 of the Salem FSAR indicate that no problem would exist.
The smaller pieces still missing are expected to easily pass up through the fuel assemblies during operation and not present any problems to the control rod drive machanisms.
The largest that any of the missing pieces could be, based on the base areas on grid assemblies, is slightly greater than 2in2 KEstinghouse has recocmended additicnal fuel assembly handling precautions
,-to minimize the potential for corner-to-corner interaction between grid assemblies.
Included among these recommendations are,1) a revised 1cading sequence which would load fuel assemblies 'from the sides of the
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core toward the center, 2) a slight offset in position as corner fuel assemblies are lowered into the core until they are about 10" above the base plate and then making a lateral adjustment into final position,
- 3) the conditionally accepted assemblies in categories 1 and 2 would be leaded in a special sequence to minimize relative motion with adjacent assemblies, 4) those assemblies in category 2 would be loaded against the core baffle, where possible and 5) revised load cell limits on the mani-pulator crane in an attemp: :o more easily detect ir. creased loads during fuel handling.
ls.
Attachment to I'E Circular No. 80-13 Meeting Summary for Salem Unit 1 Westinghouse acknowledged and summarized similar grid assembly problems that have occurred at other facilities.
Although these other occurrences did not involve as many fuel assemblies as in this Salem situation, similar damage has been observed to 14x14,15x15 &nd 17x17 fuel assembifes.
In some instances the fuel was removed, and in others, the fuel was re-loaded with no known adverse effects.
With regard to the Salem Unit 1 refueling analysis, the licensee indicated praliminarily, that the core parameters are expected to be essentially unchanged due to the revised core loading that will result.
The licensee agreed to address the potential effects that the unaccounted for pieces of grid material might have on the core thermal hydraulic analysis and on control rod operation.
This information will be included prior to restart of Salem 1 in a supplement to the licensee's reload 1
application for cycle 2.
@s Gary G. Zech, Project Manager Operating Reactors Branch #1 Division of Operating Reactors
Enclosure:
List of Attendees cc:
w/ enclosure j
see next page 6
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ENCLOSURE 2 IE Circular No. 80-13 Date:
May 28, 1980 Page 1 of 1 RECENTLY ISSUED IE CIRCULARS Circular Subject First Date Issued To No.
of Issue 80-03 Protection from Toxic 3/6/80 All Power Reactor Facil-Gas Hazards ities with an (Operating License (OL) 80-04 Securing Threaded Lack-3/14/80 All Power Reactor Facil-ing Devices on Safety-ities witi an OL or CP l
Related Equipment 80-05 Emergency Diesel Gen-4/1/80 All Power Reactor Facil-erator Lubricating Oil ities with an OL or CP Addition and Onsito Supply 80-06 Control and Account-4/14/80 Medical Licensees in ability Systems for Categorio G and G1 Implant Therapy Sources 80-07 Problems with HPCI 4/3/80 All Power Reactor Facil-Turbine Oil System ities with an OL or CP 80-08 BWR Technical Speci-4/18/80 All General Electric fication Inconsis-BW'ts holding a power tency - RPS Response rcactor OL Time 80-09 Problems with Plant 4/28/80 All holders of Internal Communi-a reactor OL cations Systems or CP 80-10 Failure to Maintain 4/29/80 All Power Reactor Environmental Facilities with an Qualification of OL or CP Equipment 80-11 Emergency Diesel 5/13/80 All Power Reactor Generator Lube Oil Facilities with an Cooler Failures OL or CP 80-12 Valve-Shaft-To-Actu-5/14/80 All Power Reactor Faci-ator Key May Fall Out of lities with an OL or CP Place When Mounted Below Horizontal Axis e