ML19323J356
| ML19323J356 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/28/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Papay L SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| NUDOCS 8006200056 | |
| Download: ML19323J356 (1) | |
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UNITED STATES 8
~N NUCLEAR REGULATORY COMMISSION
,E REGION V g
1990 N. CALIFORNIA BOULEVARD O
SUITE 202, WALNUT CREEK PLAZA g *,,,* d WALNUT CREEK, CALIFORNI A 94596 May 28, 1980 Docket No. 50-206 Southern California Edison Company P. O. Box 800 2244 Walnut Grove Avenue Rosemead, California 91770 Attention: Dr. L. T. Papay, Vice President Advanced Engineering Gentlemen:
The enclosed Circular No. 80-13, is forwarded to you for information.
If there are any questions related to your understanding of the suggested actions, please contact this office.
Sincerely, 10r%2C-R. H. Engelken Director Enclosures :
1.
IE Circular No. 80-13 2.
List of Recently Issued IE Circulars cc w/ enclosure:
J. M. Curran,SCE R. Dietch, SCE THIS DOC' 1T CONTAINS POOR JTY PAGES 80062 000STo
.s SSINS No.: 6830 Accessions No.:
UNITED STATES 7910250495 NUCLEAR REGULATORY COMMISSION T
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0FFICE OF INSPECTI91 AND ENFORCEMENT WASHINGTo" D.C. 20555
-' J May 28, 1980 IE Circulac No. 80-13 GRID STRAP DAMAGE IN WESTIflGH0VSE FUEL ASSEMBLIES Description of Circumstances:
During the refueling operation at Salem Unit 1, it was noted by the licensee that some of the assemblies 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 cate-gcries: small pieces missing (15 assemblies), grid material ripped and laid over (5 assemblies), larger sections missing and fuel pins exposed (11 assemb-lies).
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 problems have occurred at other facilities fueled with 14X14 and 15X15 Westingho ise assemblies; however, fewer assemblies were damaged in those instances.
Re::ommended Actions:
All licensees using 14X14, 15X15, or 17X17 Westinghouse assemb'ies are advised to:
1 (1) Visually inspect grid straps of those fuel assemblies which are discharged from the core as well as those assemblies which are moved to the spent fuel pool for control rod replacement and are subsequently returned to the core.
IE Circular No. 80-13 May 28, 1980 Page 2 of 2 (2) Review the fuel handling precautions recommended by Westinghouse at a meeting on May 25, 1979, with URC 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 regarding these matters, contact the Director of the appropriate NRC Regional Office.
Attachment:
Summary of Meeting Notice dated 5/30/79 1
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IE Circular No. 80-13 Enclosure May 28,.1980 RECENTLY ISSUED IE CIRCULARS Circular Subject Date of Issued to No.
Issue 80-12 Valve-Shaft-To-Actuator Key 5/14/80 All holders of Reactor May Fall Out of Place When OLs and cps Mounted Below Horizontal Axis 80-11 Emergency Diesel Generator 5/13/80 All holders of a power Lube Oil Cooler failures reactor OL or CP 80-10 Failure to Maintain 4/29/80 All holders of Reactor Environmental Qualification OLs and cps of Equipment 80-09 Problems With Plant Internal 4/28/80 All holders of a power Communications Systems reactor OL or CP 80-08 BWR Technical Specification 4/18/80 All General Electric Inconsistency - RPS Response BWR's holding a power Time reactor OL 80-07 Problems with HPCI Turbine 4/3/80 All holders of a power Oil System reactor OL or CP 80-06 Control and Accountability 4/14/80 Medical licensees in Systems for Implant Therapy Categories G and G1
-Sources 80-05 Emergency Diesel-Generator 4/1/80 All holders of a power Lubricating Oil Addition and reactor OL or CP Onsite Supply 80-04 Securing of Threaded Locking 3/14/80 All holders of a power Devices on Safety-Related reactor OL or CP Equipment 80-03
-Protection from Toxic Gas 3/6/80 All holders of a Hazards power reactor OL 80-02
. Nuclear Power Plant Staff 2/1/80 All holders of Reactor
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Work Hours Ols, including research and test reactors, and cps
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UNITED STATES g
NUCLEAR REGULATORY COMMISSION a
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- 30M Docket No. 50-272 LICENSEE:
PUBLIC SERVICE ELECTRIC & GAS COMPANY (PSE&G)
FACILITY: SALEM UNIT NO. 1
SUBJECT:
SUMMARY
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 &
4 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 the; current refueling outage for cycle 2.
A list of attendees is enclosed.
i Significant discussions are sumarized below.
The licensee and Westinghouse provided a detailed discussion of the damage observed to the Salem fuel grid assemblies during the cycle 2 refueling outa5e which comenced in April 1979.
Due to the indications
. ' observed during the initial stager, of the outage, the decision was made to unload all fuel assemblies frca the core.
Of the fuel assemblies (193) inspected, 28 assemblies ware determined to have varying degrees cf damage to cne or more of the eight grid assemblies per fuel assembly.
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The grid asse-blies provide lateral support to the fuel rods.
In no case was dacage cbserved to the fuel rods themselves.
The grid assembly
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damage observed, which was generally located at the corners of the grid assemblies, was categorized as follows:
1 Category Type of Damage No. of Grid Assemblies 1
small pieces missing 15 2
grid material ripped and laid over 4
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3 larger sections missing and 9
fuel pins exposed i
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Meeting Sumary for i
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 2i as a precautionary measure assemblies with category 3 damage will not be reloadad. 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 reuse 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 da:nage occurred during fuel insertion for cycle 1, or during re:noval 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 assemblies have been removed and soras degree of lateral movement is possible.
Under these conditions the grid assemblies may have been aligned such that the corners interacted during vertical movement.
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Of the pieces missing (about 61), a total area of about 25in2 is involved.
These pieces range from about.31nZ up to about 5.5fn2 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 originally missing were to be located such as to partially block the inlet nozzle area of the ene fusi assembl, analyses similar to that described in t
Section 3.4 of the Salem FSAR indicate that no problem would exist. The smaller pieces still missing are expected to casily pass up through the i
1 fuel asse:nblies during operation and not present any problems to the control rod drive mechanisms.
The largest that any of the missing pieces could be, based on the base areas on grid assemblies, is slightly greater than 2in2 j
j Westinghouse has reco::: mended additicnal fuel at embly handling precautions to minimize the potential for corner-to-corner interaction between grid i
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assemblies.
Included among these recomendations are,1) a revised loading sequence which would load fuel assemblies 'from the sides of the 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
-loaded in a special sequence to minimize relative motion with adjacent assemblies, 4) those assemblies in category 2 would be loaded against the core baffle, whera possible and 5) revised load cell limits on the mani-pulator crane in an attempt to more easily detect increased loads during fuel handling.
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(nr 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 and 17x17 fuel assemblies.
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 preliminarily, 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 enterial 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 i
application for cycle.2.
g Gary G. Zech, Project Manager Operating Reactors Branch #1 Division of Operating Reactors
Enclosure:
List of Attendecs cc: w/ enclosure See next page l
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