ML19320D527

Forwards IE Circular 80-13, Grid Strap Damage in Westinghouse Fuel Assemblies. No Written Response Required

ML19320D527
Person / Time
Site:	Summer
Issue date:	05/28/1980
From:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:	Mary Johnson SOUTH CAROLINA ELECTRIC & GAS CO.
References
NUDOCS 8007210471
Download: ML19320D527 (1)

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o ATLANTA, GEOMORA 30303 In Reply Refer To:

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THIS DOCUMENT CONTAINS P0OR QUAUTY PAGES South Carolina Electric and Gas Company Attn:

M. C. Johnson, Vice President Special Services and Purchasing Post Office Box 764 Columbia, South Carolina 29218 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,

)

James P. O'Reilly Director

Enclosures:

1.

IE Circular No. 80-13 2.

List of Recently Issued IE Circulars l

8 0 0 7 210 y'y m

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MAY 281900 South Carolina Electric 4

and Gas Company f cc w/ enc 1:

T. B. Conners, Jr.

Conners, Moore and Corber 17p7PennsylvaniaAvenue,N.W.

Washington, D.C.

20006 A. A. Smith Quality Assurance Post Office Box 8 Jenkinsville, South Carolina 29065 O. S. Bradham, Manager Nuclear Operations Post Office Box 8 Jenkinsville, South Carolina 29065 Of l

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UNITED STATES 7910250495 NUCLEAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 6

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May 28, 1980 IE Circular No. 80-13 GRID STRAP DAMAGE IN WESTINGHOUSE 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-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 vertica:. loading and unloading movements. No correlation of the damage to core location, grid strap elevation, or manufseturing and shipping batches has been identified.

i 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 Westinghouse assemblies; however, fewer assemblies were damaged in those instances.

Recommended Actions:

All licensees using 14X14, 15X15, or 17X17 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.

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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 t

(Attachment 1). ' Adopt those recommendations which are pertinent.

No written response to this Circular is required.

If you require 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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SUBJECT:

SLAFARY OF MEETING HELD ON MAY 25, 1979 TO DISCUSS

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DAMMiE OBSEAVED TO FUEL GRIO ASSEMBLIES DURING THE E 10 % % :d!# P SALEM UNIT NO. 1 REFUELING OUTAGE

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.r On May 25, 1979, we met with representatives of Public Service Electric &

i Gas Company (PSE&G) and Westinghouse to discuss the cause and extant of damage observed to the Salem Unit No.1 fuel grid assemb, lies during the current refueling outage for cycle 2.

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Significant discussions are sumarized below.

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2~qpsk The licensee and Westinghouse provided a detailed discussion of the damage observed to the Salem fuel grid assemblies during the cycle 2 m*6..Mg N

• m refueling outage which comenced in April 1979.

Due to the indications

. ' observed during the initial stages of the outage, the decision was made to unload all fuel assemblies from the core.

Of the fuel assemblies i,

(193) inspected, 28 asse:nblies were determined to have varying degrees ;. -

f, of damage to one or more of the eight grid assemblies per fue assembly.

t The grid asse=blies provide lateral support to the fuel rods.

In no case was damage observed to the fuel rods themselves.

The grid assembly damage observed, which was generally located at the corners of the grid aste::iblies, wks categorized as follows:

Capao.ry.

Type of Damage No. of Grid Assemblies hh 1

saal1 pieces missing 15 2

grid material ripped 4

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larger sections missing and S

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. for cycle ti as a pricaut.ionary measure assemblies with category 3 damage j

will not be reloaded. The basis for this determination was that assemblies with category 1 and 2 damage can he used without any loss of function of

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longer fully restrain all fuel rods in the manner provided for in the des gn. 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 5

whether the damage occurred during fuel insertion for cycle 1. or during removal or readjustments for cycle 2 or both.

It is believed that cotur-to-corner interaction may have occurred between grid assemblies l

of adjacent fuel assemblies especially when diagonal fuel assemblies have i

been removed and some degree of lateral revement 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), g total area of about 25fn2 is involved.

These pieces range from about.3fnc up to about S. Sin 2 Approximately i

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 l

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 one fuel assembl. analyses similar to that described in Section 3.4 of the Salem FSAR indicate that no problem would exist. The i

sneller 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 mechanisms.

The largest that any of the missing pieces could be than ZinI. based on the base arest on grid assemblies, is slightly greater

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Westinghouse has reconnended additienal fuel assembly handling precautions to minimize the potential for corner-to-corner interaction between grid assemblies.

Included among these reconnendations are,1) a revised loading sequence which would load fuel assemblies from the sidas 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 assembifes in categories 1 and 2 would be Toaded in a special sequence to minimize relative motion with adjacent i

assemblies, 4) those assemblies in category 2 would bc loaded against the core baffle, where 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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.g;j-that have occurred at other facilities. Although these other occurrences s.

did not involve as mary 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 Sales Unit I 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 ehfects that the unaccounted

.m for pieces of grf 4 material might have on the core thermal hydraulic analysis and on control rod operation.

This information will be included prior to restart of Salen 1 in a supplement to the licensee's reload application fbr c;ycle 2.

Gary G.

h. Project Manager Operating Reactors Branch #1

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Division of Operating Reactors

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Enclosure:

List of Attendees cc: w/ enclosure i

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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 80-13 Grid Strap Damage in 5/28/80 All holders of R.ector Westinghouse Fuel Assemblies OL and Constructim.

Permits for PWRs 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 e

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 Gystems 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 i

80-02 Nuclear Power Plant Staff 2/1/80 All holders of Reactor L

Work Hours-OLs, including research i

and test reactors, and cps j

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