ML20236A188
| ML20236A188 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/09/1989 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8903160459 | |
| Download: ML20236A188 (3) | |
Text
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TENNESSEE VALLEY AUTHORITY 5N 157B Lookout Place t
MAR 091989 3
U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SQN) - ADDITIONAL INFORMATION FOR TECHNICAL SPECIFICATION (TS) CHANGE 89-15, R0D CLUSTER CONTROL ASSEMBLY (RCCA) WEAR
Reference:
TVA's letter to NRC dated January 31, 1989, "Sequoyah Nuclear Plant (SQN) - Technical Specification Change 89-15" Enclosed is the additional information requested to support NRC review of TVA's TS change 89-15.
This information was requested during a February 22, 1989, telephone conference call between Tom Rotella, NRC, and Don Goodin, SQN Regulatory Licensing.
Please direct questions concerning this issue to D. V. Goodin at (615) 843-7734.
Very truly yours, TENNESSEE VALLEY AUTHORITY R. G idley, Ma ager Nuclear Licens ng and Regulatory Affairs Enclosure cc: See page 2 A
UcSD
/J 8903160459 890309 PDR ADOCK 05000327 P
PDC An Equal Opportunity Employer
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.J MR 09 m U.S. Nuclear Regulatory Commission 1
cc (Enclosure):
Ms. S. C. Black, Assistant Director for Projects l'
TVA Projects Division L
U.S. Nuclear Regulatory Commission' One White Flint, North 11555 Rockville. Pike Rockville, Maryland 20852 Mr. F. R. McCoy, Assistant Director for Inspection Programs TVA Projects Division U.S. Nuclear Regulatory Commission Region II 101 Marietta Street NW, Suite 2900 Atlanta, Georgia 30323 Sequoyah Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 1
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ENCLOSURE I
NRC QUESTION i
Would repositioning SQN's rod cluster control assemblies (RCCAs) at 222 steps l
i as opposed'to 228 steps result in material degradation to the rodlet tips because of higher neutron fluence?
TVA RESPONSE SQN's rodlets are composed of silver-indium-cadmium that is not as susceptible to cracking as rodlets composed of hafnium.
Positioning the SQN RCCAs at 222 steps as opposed to 228 steps would not have life-limiting consequences.
The RCCA absorber material would experience some increased swelling because of the higher neutron fluence at the tips; however, this.is considered by TVA and Westinghouse Electric Corporation (W) to be inconsequential (reference Electric Power Research Institute Report NP512 dated March 1986).
It should be noted that SQN's control bank D is positioned below 222 steps (200-220 steps) during normal power operation.
Control bank D is inserted partially into the core during power operation to provide power control and axial flux shaping.
To date, SQN has not experienced any cracking in control l
bank D rodlets.
Experience has shown that the SQN bank D rodlets, which have operated for an extended period, have not experienced any significant material damage. This has been verified by eddy current testing inspection during SQN's unit 2 cycle 3 refueling outage.
TVA also verified with W that all of the SQN RCCAs (shutdown and control banks) are identical to bank D in design and construction.
TVA therefore concludes that the repositioning of SQN's RCCAs at 222 steps would not result in material damage to the rodlets or pose a safety concern.
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