ML18045A369
| ML18045A369 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/28/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 8007210358 | |
| Download: ML18045A369 (7) | |
Text
Docket No. 50-255 Consumers Power Company ATTN:
Mr. R. B. DeWitt Vice President Nuclear Operations 212 West Michigan Avenue Jackson, MI 49201 Gentlemen:
CENTRAL FILES LMAY 2 8 1980 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.
Enclosure:
IE Circular No. 80-13 cc w/encl:
Mr. D. P. Hoffman, Nuclear Licensing Administrator Mr. J. G. Lewis, Manager Central Files Director, NRR/DPM Director, NRR/DOR PDR Local PDR NSIC TIC Ronald Callen, Michigan Public Service Commission Myron M. Cherry, Chicago RIII HeiJ:an/km 5/28/80 Sincerely, James G. Keppler Director
\\
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 May 28, 1980 GRID STRAP DAMAGE IN WESTINGHOUSE FUEL ASSEMBLIES Description of Circumstances:
SSINS No.: 6830 A~cessions No.:
7910250495 IE Circular No. 80-13 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-gories: 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 17Xl7 Westinghouse assemblies.
Similar grid problems have occurred at other facilities fueled with 14Xl4 and 15Xl5 Westinghouse assemblies; however, fewer assemblies were damaged in those instances.
Recommended Actions:
All licensees using 14Xl4, 15Xl5, or 17Xl7 Westinghouse assemblies are advised to:
(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 NRC and the licensee for Salem (Attachment 1).
Adopt those recommendations which are pertinen~.
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
IE Circular No. 80-13 May 28, 1980 RECENTLY ISSUED IE CIRCULARS Circular No.
'80-12 80-11 80-10 80-09 80-08 80-07 80-06 80-05 80-04 80-03 80-0t-Subject Valve-Shaft-To-Actuator Key May Fall Out of Place When Mounted Below Horizontal Axis Emergency Diesel Generator Lube Oil Cooler Failures Failure to Maintain Environmental Qualification of Equipment Problems With Plant Internal Communications Systems BWR Technical Specification Inconsistency - RPS Response Time Problems with HPCI Turbine Oil System Control and Accountability Systems for Implant Therapy Sources Emergency Diesel-Generator Lubricating Oil Addition and Onsite Supply Securing of Threaded Locking Devices on Safety-Related Equipment Protection from Toxic Gas Hazards Nuclear Power Plant Staff Work Hours Date.of Issue 5/14/80 5/13/80 4/29/80 4/28/80 4/18/80 4/3/80 4/14/80 4/1/80 3/14/80 3/6/80 2/1/80 Enclosure Issued to _
All holders of Reactor OLs and CPs All holders of a power reactor OL or CP All holders of Reactor OLs and CPs All holders of a power reactor OL or CP All General Electric BWR 1s holding a. power reactor OL All holders of a power reactor OL or CP Medical licensees in Categories G and Gl All holders of a power
- reactor OL or CP All holders of a power reactor OL or CP All holders of a power reactor OL All holders of Reactor OLs, including research and test reactors, and CPs
Docket No. 50-Z72 UNITED STATES NUCLEAR REGULATORY COMMISSION WA.Sl"CINCiTON, D. C. ZUSSS MAY 3 0 1979 LICENSEE:
PUoLIC SERVICE ELECTRIC & GAS COMPANY (PSE&G)
FACILITY:
SAL.EH UNIT HO. l
SUBJECT:
SUP'Ji.ARY OF KEETINS HELO ON MAY 25, 1979, TO DISCUSS DAf-tASE OBSERVED TO FUEL GRID ASSEMBLIES DURING THE SALEM UNIT HO. 1 REFUELING OUTAGE On ~~Y 25, 1979, we met with representatives of Pub1fc Service Electric &
Gas Company (PSE&G) and Westinghouse to discuss the cause and extent of damage observP~ to the Salem Unit.No. l fuel grid assemblies during the current refueling outage for cycle 2.
A list of attendees is enclosed.
Si;nificant diseussions are surranarized below.
The licensee and ~estinghouse provided a detailed discussion of the da~age observed to the Salem fuel grid essemb1ies during the cycle 2 refueling ou~;e which co!Tl'Tienced in Apr;l 1979.
Due to the indications
. observed during the initia1 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 detennined to have varying degrees of :!ar..age to cne or more of the eight grid assemblies per fuel assembly.
The grid asse~biies provide lateral support to the fuel rods.
In no case w~s da~age observed to the fuel rods themselves. The grid assembly dar..age observer!, which was generally located at the corners of the grid asss~blies. was ca~egorized as follows:
Ca~egory Type of Damage No. of Grid Assemblies 1
small pieces missing 15 z
grid ~terial ripped 4
end laid over 3
~arger sections missing and 9
fuel pins exposed
,I Meet fng Sumnary for Salem Unit l 1
I e
.Of the above, fuel assemblies with categories 1 and 2 damage were detennined by the licensee to be acceptable*for use and will be reloaded fo.r cycle 2; as a precautionary measure assemb1 ies with category 3 damage will not be reloaded. The basis for this detenn1nat1on was*that assBnblies with cat~ory 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 damage occurred during fuel insertion for cyele 1. or during removal or readjustments for cyele 2.* or both. It is be1 ieved that conier-to-corner interaction may have occurred between grid assemblies of adjacent fuel asses;blies especially when diagonal fuel assemblies have -
been rf$l0Ved and some degree of bteral movement is possible. Under these conditions the grid assemblies may have been aligned such that the corners interacted during vertical movement.
Of the pieces missing {about 61), o total area of about 25in2 fs involved.
These pieces range from about.3fnZ up to about S.5in2.
Approximately 121n2 of material has been recovered from' the core or the fuel assemb1ie.s 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 part1a11y block the inlet noz:.zle area of the one fuel ~ssembl. analyses 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 ass~~hlies dur1ng operation and not present any problems to the control rod drive mechanisms.
The largest that any of the m1~sing pieces could be, based on the base areas on grid assemblies, 1s slightly greater than 21n2.
Westinghouse has recor.:nended add1t1c~al fuel assembly handling precautions to minimize the potentia1 fer corner-to-eorner interaction between grid assemblies.
Inc1uded among these reconmendations are, 1) a revised loading sequence which would load fuel assemblies 'from the Sides of the core toward tha ~.nter, 2) a slight offset in position as corner fuel assemblies are lowered into the core until they are about 10 11 above the ba-s-e plate and then making a lateral adjustment into final position,
- 3) the conditionally accepted assemblies 1n categories l and 2 would be loaded in a special sequence to minimize re1ative motion w1th adjacent ass~blies. 4) those assemblies in category 2 would be loaded against the core baff1e, ~here possible and 5) revised load cell limits pn the man1*
pulator crane in an atte:npt ~ more easilY. detect increAst;d* loAds during fuel handling.
f Meeting Surrrnary for Salem Unit 1
- 9
(......
- -- Westinghouse acknowledged and si.r.rrnarized sim11ar grid assembly problems that have occurred at ether facilities. Although these other occurrences did.not involve as many fuel assemblies as in this Salem situation, similar damage has been observed to 14x14, 1Sx15 and 17x17 fuel assemblies.
In some 1nstances the fuel wa~ 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 w111 result.
The licensee agreed to address the potential effects that the unaccounted for pieces of grfd material might have on the core thermal hydraulic analysis and on control rod operation. This infonnation will be included prior to restart of Salem l in a supplement to the licensee's reload application for cycle 2.
Enclosure:
List of Attendees cc: w/enelosure Se:e next page
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Gary G. Zech. Project Manager Operating Re~ctors Branch 11 Division of Operating Reactors