ML19263D738
| ML19263D738 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 04/06/1979 |
| From: | Justin Fuller PUBLIC SERVICE CO. OF COLORADO |
| To: | Gammill W Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19263D739 | List: |
| References | |
| FOIA-81-127 P-79070, NUDOCS 7904130208 | |
| Download: ML19263D738 (2) | |
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April 6, 1979 Fort St. Vrain Unit flo.1 P-79070 Mr. William P. Gammill Assistant Director for Standardization and Advanced Reactors Division of Project Management U.S. liuclear Regulatory Commission Washington, D.C.
20555 Docket #50-267
Subject:
Installation of Region Constraint Devices Gentlemen:
In past conversations with members of the staff and in various corres-pondence, Public Service Company of Colorado has indicated that the Region Constraint Devices (RCD's) that haw been developed by General Atomic as a possible solution to the Fort St. Vrain temperature fluctuation phenomenon would be available for installation in the reactor at the time of the first refueling.
There has also been some discussion as to the advisability of installing these devices at this time.
At the time of refueling, the configuration of the reactor core is to be modified by the installation of fresh fuel in six regions.
The addi-tion of the fresh fuel in these regions will require the use of a revised control rod withdrawal sequence.
In addition, the instrumented control rod drives are to be installed in regions 5 and 35 to monitor core temperature and neutronic variations during reactor temperature fluctuations.
It is PSC's concern that if the Region Constraint Devices are installed at this time, their affect on the reactor's tendency toward temperature fluctuations under normal operating conditions would be masked because of the other changes made as a result of the refueling.
It is, therefore, the Public Service Company of Colorado's intent to proceed as follows:
1.
During the present refueling, tests would be completed to insure that the Region Constraint Devices could be installed and re-moved from the reactor core, utilizing the fuel handling machine.
If problems are experienced, appropriate modifications would be made to the Region Constraint Device or fuel handling equipment to resolve the installation and/or removal problem (s).
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Mr. William P. Ganmill April 6,1979 Page 2 2.
Following the return of the reactor to power, a series of tests following the general philosophy of the RT500 would be run to establish the " threshold" line of temperature fluctuations in the Cycle 2 core.
This data would be collected, analyzed and the results forwarded to the Conmission for their review.
Compari-sons to Cycle 1 data would also be made.
3.
The reactor would then be operated at as high a power level as would be consistent with the results of the testing completed under the RT through the sunmer months.
4.
Sometime this fall, consistent with system load requirements and maintenance schedule of other generating units, Fort St.
Vrain would be shutdown and the Region Constraint Devices installed.
5.
Following the reactor's return to power, a series of tests utilizing the philospohy of RT500 would be run to determine the affects of the Region Constraint Devices on the tempera-ture fluctuation threshold as determined under Item 2 above.
The data from this series of tests would be analyzed and the results forwarded to the Conmission for their information and further discussion.
PSC considers this schedule to be advantageous because it will allow us to:
1.
Test our ability to insert and withdraw the Region Constraint Devices in the core and will allow for any modifications prior to any long-term installation of these devices with the reactor at power.
2.
It will allow separate determination of the affects of refueling and the installation of the Region Constraint Devices on the temperature fluctuation " threshold".
3.
It will allow a direct comparison of Cycle 1 and Cycle 2 fluc-tuation data.
Public Service Company of Colorado will be available to discuss this plan at your convenience.
Very truly yours, J.K. Fuller, Vice President Engineering and Planning JKF/FES:ler