ML18344A399

LER 1975-010-00 for Palisade Nuclear Plant, Axial Growth of Poison Rods in the A&B Type Fuels

ML18344A399
Person / Time
Site:	Palisades
Issue date:	10/14/1975
From:	Bixel D Consumers Power Co
To:	Purple R Office of Nuclear Reactor Regulation
References
LER 1975-010-00
Download: ML18344A399 (3)

Text

consumers

• Power company General Offices: 212 West Michigan Avenue, Jackson, Michigan 49201

• A rea C ode 51 7 788-0550 October 14, 1975 "Re~latoJYl \9.

Director of Nuclear Reactor Regulation Att: Mr Robert A. Purple, Chief nEC[/V£D Operating Reactor Branch No 1 OCT 201975 ...

US Nuclear Regulatory Commission ll.S .N*tr .,

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Washington, DC 20555 Mail Section DOCKEI' 50-255, LICENSE DPR PALISADES PLANT - UE-75-10 Attached is Unusual Event Report 75-10 which concerns the receipt of pre-liminary information on axial growth of poison rods in the A&B type fuels at Palisades.

Investigation of this event is continuing.

David A. Bixel Assist ant Nuclear Licensing Administrator CC: JGKeppler, USNRC File

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• 1. Report Number:

UNUSUAL EVENT REPORT 75-10 Palisades Plant UE-75-10, Docket 50-255.

2. a. Report Date: October 13, 1975.

b. Event Date: October 2, 1975 (information received).

J. Facility: Palisades Plant, Covert.

4. Identification of Event: Poison rod growth in Palisades fuel.

5. Condition Prior to Event: Plant operating at 80% power.

6. Description of Event: Preliminary information received from the Palisades fuel supplier indicates that the axial growth of poison rods in the A&B type fuels may have reached the limit allowed in the fuel bundle design.

7. Designation of Apparent Cause: Preliminary information available in the industry indicates that the most probable cause is related to radiation-induced growth .

• 8. Analysis of Event: Based on preliminary evaluations, we have concluded that continued poison rod growth following touchdown could cause the poison rod to gradually bow. This, in turn, could have an effect on the heat transfer capability of the adjacent fuel rods. Any effect on the fuel clad integrity would be gradual. The corrective action described in No 9 below is designed to provide more margin than is normally available and to promptly detect any abnormal fuel clad degradation that might occur. At the heat fluxes ex-perienced at present operating levels, considerable degradation of heat transfer can occur without jeopardizing fuel rod integrity.

Further, based on observations at the last fuel inspection, only approximately one of twenty poison rods had experienced the growth phenomenon to the extent that it was observable, We are pursuing this event with the fuel supplier and will keep you informed.

9. Corrective Action: As an interim measure, we observe the following:

a. Administratively we are limiting the power level to a nominal 80%

(of 2200 MWt).

b. As required in Appendix B of the Technical Specifications, we are monitoring the primary coolant gross gamma radioactivity continuously or by daily samples.

• 10. Failure Data: N/A .

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