ML20062M141
| ML20062M141 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 08/16/1982 |
| From: | Clayton F ALABAMA POWER CO. |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8208200006 | |
| Download: ML20062M141 (2) | |
Text
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Milling Addrrs Alabama Power Company 600 North 18th Sheet Post Office Box 2041 Birmingham, Alabama 35291 Telephone 205 783-6081 F. L Clayton, Jr.
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ne soumem eteac syuem August 16, 1982 Docket No. 50-348 Director, Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Mr. S. A. Varga Joseph M. Farley Nuclear Plant - Unit 1 Refueling Outage Plans
Dear Mr. Varga:
Farley Nuclear Plant Unit 1 is currently experiencing higher than expected reactor coolant system activity levels.
Investigation of the apparent fuel leakage producing these activity levels without the benefit of direct visual inspection indicates that excessive clearances of the reactor i
vessel lower internals baffle joints are probably the cause. These excessive clearances allow unacceptable water jetting (baffle jetting) on certain fuel assembly rods thereby inducing fuel rod fretting.
In an effort to close some of the baffle joints referenced above, peening of the baffle gaps was employed during the last refueling outage on Farley Unit 1.
Based upon recent evaluation of the peening operation performed at other plants, the baffle peening employed at Farley was probably not completely successful and in fact could have exacerbated the baffle joint clearance problem.
Alabama Power Company, in concert with Westinghouse Electric Corporation, is performing extensive planning and development work to correct the baffle jetting problem. The modification planned to resolve baffle jetting is to convert reactor coolant flow between the core barrel and the baffles from downflow to upflow. This modification, which will reduce the pressure differential across the baffle joints, will be performed by plugging the holes in the lower reactor vessel internals core barrel and by the drilling of holes in the lower reactor vessel internals upper former plate. Tooling and equipment design for this modification is currently under development with a scheduled completion date of January 1983.
If all preparations for this modification proceed satisfactorily and current Unit 1 refueling plans for January 1983 are maintained, Alabama Power Company-will make the upflow conversion during this refueling outage.
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o Mr. S. A. Varga August 16, 1982 Director, Nuclear Reactor Regulation Page 2 If for some reason the upflow modification development work is not completed in time for the refueling outage, it is highly probable that fuel rod and assembly modifications similar to those employed at the Trojan Nuclear Plant will be required for Farley Unit 1.
These modifications entail the replacement of selected fuel rods with stainless steel rods and the addition of intermediary mini-grids in those assemblies subject to the effects of baffle jetting. These changes result in strengthening of the fuel assemblies thereby allowing them to withstand the jetting effects.
After the unit is shutdown for refueling, an evaluation on the reactor internals and fuel conditions will be completed. Based on the results of evaluations and the options available at the time, Alabama Power Company will take appropriate corrective action. The NRC will be notified of the selected course of action at the earliest possible date.
If the upflow modification is made,10CFR50.59 will be utilized to verify that all licensing bases have been met for the modification and the new reactor core.
If the stainless steel rod and/or mini-grid modifications are made to fuel assemblies, appropriate Technical Specification changes will be submitted.
Current reactor coolant system radiochemistry is well within the Technical Specification limits and it does not appear that these limits will be approached prior to the scheduled refueling outage of January 1983.
Alabama Power is not making these limits the sole criteria for continued reactor operation; the effects of the increased reactor coolant system activity on personnel exposure, contamination control, and cleanup capability are being carefully monitored. Preliminary evaluation of Dose Equivalent Iodine (DEI) bases indicates that rargins on the order to 40-60%
above present Technical Specification limits exist due to recently revised NRC methodology for calculating DEI combined with specific analyses for Farley. Even though it appears that it will not be necessary, a change to this limit could be needed to allow continued operation of the unit until a time when shutdown would be more appropriate. A situation of this type could arise if the upflow conversion modification tooling and equipment development were not completed and ready for implementation.
Our staff has discussed these matters with the Farley Nuclear Plant Project Manager, Mr. E. A. Reeves, and will continue to keep him appraised of the unit status and outage plans as they become more clear.
If you have any questions, please advise.
Yours very truly, L. Clayton, r.
FLCJ r/ JAR:1 sh-D23 cc:
Mr. R. A. Thomas Mr. G. F. Trowbridge Mr. J. P. O'Reilly.
Mr. E. A. Reeves Mr. W. H. Bradford M