ML19261A435
| ML19261A435 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 01/11/1979 |
| From: | Justin Fuller PUBLIC SERVICE CO. OF COLORADO |
| To: | Gammill W Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19261A436 | List: |
| References | |
| NUDOCS 7901180172 | |
| Download: ML19261A435 (3) | |
Text
{f(l public Service Company F Odwade l
jj P.O. BOX 840 DENVER COLORADO 80201 Y
January 11, 1979 Fort St. Vrain Unit No. 1 P-79012 Mr. William P. Gammill Assistant Director for Standardization and Advanced Reactors Division of Project Management Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Docket #50-267 Su bject:
Nuclear Detector Decalibration Gentlemen:
Technical analyses of the Fort St. Vrain (FSV) initial core, corrob-orated by plant operating data, indicate that decalibration of the power-range detectors can occur at Fort St. Vrain due to motion of control rod I'.n k s. As the detectors are located outside the core, the majority of the neutrons reaching the detectors originate in the cuter core regions.
With-drawl of a rod bank near the core centerline will thus cause the detectors to underpredict the true power changes while outer bank withdrawl results in overprediction of true power changes.
The results of a decalibration analysis are summarized in the enclosed document titled "The Effect of Nuclear Detector Decalibration on the Fort St. Vrain Reactor and Suggested Corrective Measures", dated January,1978.
Recommended circuit designs to supplement the current single-level trip setpoint with a " floating" trip setpoint have been identified as the solu-tion to the neutron detector calibration problem.
This approach has been reviewed by the FSV Nuclear Facility Safety Committee and has received unanimous approval for implementation at Fort St. Vrain.
As the intended modifications will not impair the control and opera-tion of Fort St. Vrain and will ensure compliance with the FSV Technical Specifications, NRC approval to perform the modifications is requested.
Very truly yours, J.K. Fuller, Vice President Engineering and Planning 7
JKF/MLP:ler a
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790118 D/ 7,2
STATE OF COLORADO
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CITY AND C00tlTY OF DEllVER)
J.K. Fuller, being first duly sworn, deposes and says; That he is Vice President, Electrical Engineering & Planning of Public Service Company of Colorado, the Licensee herein; that he has read the attached submittals and knows the contents thereof, and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.
g Fuller Subscribed and sworn to before me this // day of gw w +y 1979.
Witness my hand and official seal.
fly commission expires:
4-3-?A
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Sc I40tary Public
BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION In the inatter of the facility Operating License)
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of
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Docket No. 50-267
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PUBLIC SERVICE COMPANY OF COLORADO
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Submittal of supplemental information pertaining to features 0F THE FORT ST. VRAIN NUCLEAR GENERATING STATION OF THE PUBLIC SERVICE COMPANY OF COLORADO Thi material is submitted for use by the Nuclear Regulatory Commission in matters pertaining to Facility Operating License, License No. DPR-34.
Respectfully submitted, PUBLIC SERVICE COMPANY OF COLORADO By M ~
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y Fuller, Vice President KELLY, STANSFIELD & 0'DONNELL Bryant O'Donnell Robert E. inompson Public Service Company Building Denver, Colorado 80202 Attorneys for Applicant