ML20129B920

Forwards Revised Base Reactivity Curve (Figure 18), Correcting Typo on X-axis & New Figure 19,incorporating Fuel Temp Dependent Adjustment to Base Reactivity.New Figure Improves Accuracy of Modeling Core Reactivity Status

ML20129B920
Person / Time
Site:	Fort Saint Vrain
Issue date:	07/24/1985
From:	Gahm J PUBLIC SERVICE CO. OF COLORADO
To:	Burnett R Office of Nuclear Reactor Regulation
References
P-85261, NUDOCS 8507290299
Download: ML20129B920 (3)

Text

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O PublicService -,o.,...

Company of Colorado 16805 WCR 19 1/2, Platteville, Colorado 80651 July 24, 1985 Fort St. Vrain Unit No. 1 P-85261 Mr. Robert Burnett, Director Office of Nuclear Reactor Regulation Operating Reactors Safeguards Branch Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Docket No. 50-267

SUBJECT:

Cycle 4 Base Reactivity Curve And Rod Withdrawal Sequence Gentlemen:

In accordance with the requirements of LC0 4.1.8 of the Fort St.

Vrain Technical Specifications, I am transmitting a revised Base Reactivity Curve (Figure 18), correcting a typographical error on the x-axis, and a new Figure 19, incorporating a fuel temperature dependent adjustment to base reactivity, which incorporates an adjustment to Figure 18 based on empirically determined trends to the 4-thermal neutron group GAUGE code base reactivity. Extensive evaluations by GA Technologies (GAT) and Public Service Company (PSC) have resulted in this new Figure 19. It is felt by both Public Service Compary and GA Technologies that use of this figure will improve the accuracy of modeling the core reactivity status.

These changes became effective with revisions to SOP 12-02, effective July 12, 1985. Reactor criticality occurred on July 21, 1985, utilizing these figures with very satisfactory results. If you have questions regarding this transmittal, please contact me at ,

(303) 785-2223.

Sincerely, fdI

1. ' J . . Gahm

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Manager, Nuclear Production Attachments JWG/JMS:djm -

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