ML20212F176
| ML20212F176 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/02/1987 |
| From: | Nauman D SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8703050038 | |
| Download: ML20212F176 (3) | |
Text
Electric & Gas Company n A.
r Columbia. SC 29218 Nuclev Operations (803) 748,3513 A SEAMACo.uay March 2,1987 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington,DC 20555
Subject:
Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Request for AdditionalInformation Fuel Assembly Reconstitution
Dear Mr. Denton:
By a letter from your staff, dated February 5,1987, a request for additional information I
was transmitted to South Carolina Electric & Gas Company (SCE&G) concerning the proposed Technical Specification change to section 5.3.1 " Fuel Assemblies". P ease find attached the response to that request.
if you should have any further questions, please ad e t uly yours, auman AMM: DAN:bjh i
Attachment c:
O. W. Dixon, J r./T. C. Nichols, Jr.
R. A. Stough E. C. Roberts G. O. Percival O. S. Bradham K. S. West J. G. Con nelly, Jr.
R. L. Prevatte D. R. Moore J. B. Knotts, Jr.
W. A. Williams, Jr.
1 & E Washington Group Managers NPCF W. R. Baehr File C. A. Price C. L. Ligon (NSRC)
R. M. Campbell K. E. Nodland 0I f0 I
8 i 8703050038 870302 ADOCK0500g5 PDR P
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l ATTAQ9ENT-
. Question'l What is the estimated radiological risk to plant' employees and-the public from fuel assembly reconstitution?
Response
-The radiological risk due to fuel reconstitution will be no
. greater than that resulting from the " worst case" single fuel assembly handling accident analyzed in the Virgil C. Summer Final Safety Analysis Report (FSAR).
The FSAR fuel handling accident postulates a worst-case radiological release due to
+
the dropping of a fuel assembly, which results in the rupture of all assembly fuel rods and their subsequent fission product release.
This FSAR accident is a bounding analysis for fuel reconstitutions since only one fuel assembly at a time may be moved and reconstituted.
Question 2 Will procedural controls for refueling operations be - followed for fuel assembly reconstitution?
Response
Fuel assembly reconstitution may require that certain specific procedural controls be established - to handle fuel movements that deviate slightly from normal refueling operations.
i Applicable refueling operation procedural controls will be adhered to as necessary.
Question 3 What experience exists with regard to fuel rod movements similar to those involved with fuel assembly reconstitution?
I
Response
SCE&G has experienced a limited amount of fuel rod movement similar to that involved with reconstitution in dealing with the Vantage 5 demonstratica asssemblies currently in the reactor core.
On previous occasions, pins have been removed and then replaced in these assemblies; however, this has been on a very small scale basis.
As explained below, significant i
experience exists within the nuclear industry as a whole on l
such movements.
l The process of irradiated fuel rod movement from fuel assemblies has been extensively utilized for over 20 years by Westinghouse. in cooperation with-various other utilities.
These movements have been part-of engineering product evaluation programs and have utilized fuel assemblies having removable rods whereby access is provided to the rods without nozzle removal. Several thousand rods have been moved by this process over the years.
Repair of fuel containing defective rods and/or defective structural components (grids) has been employed by Westinghouse and others for many years.
Westinghouse's largest campaign as far as number of units involved, was for a non-domestic reactor and involved the modification of seventeen irradiated assemblies by top nozzle removal.
Eleven PAGE 10F 2
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- y fuel assemblies were reconstituted; a substitution of several stainless steel rods was made for those fuel rods identified by ultrasonic- (UT) inspection as having failed.
Six fuel assemblies having sustained structural damage were reassembled by - transferring all serviceable : rods from the damaged fuel assembly to e.J new structural assembly (skeleton). ' 'Where replacement rods were necessary, both' new non-irradiated enriched fuel rods and stainless steel rods were used.
Operations.were completed in~ August 1985, and 'many of these fuel assemblies were included in the last core loading ~and are currently being utilized.-
More recently, irradiated fuel modifications were implemented at two domestic plants containing Westinghouse fuel.
A total of three non-defective fuel assemblies were modified to increase their ' resistance to potential baffle cross flow impingement damage.
Several stainless steel rods were substituted for fuel rods by inverting the fuel and removing the bottom nozzle. These fuel assemblies were scheduled to be loaded in core locations whpre fuel-had potential ft,r damage in the next cycle.
A fuel modification campaign was completed by Westinghouse in February 1987 for a domestic utility.
In this case, three Westinghouse assemblies were reassembled (full transfer of all rods to a new skeleton) and 2 reconstituted (substitution of several stainless rods for UT detected failed rods).
Since the campaign was just completed, these fuel assemblies have not yet been put into operation.
This effort was implemented by bottom nozzle removal.
Similar repair operations have been conducted by others, both in the~ United States and overseas.
For example, during late 1985 at a domestic
- plant, 25 fuel assemblies were reconstituted by bottom nozzle removal with several stainless rods per assembly being substituted for defective rods detected by UT.
These assemblies were reinserted into the reactor core #
additional burnup.
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