ML20155E198

Requests That NRC Review & Approve Encl Tech Spec Change Re Proposed Wording to UVAR

ML20155E198
Person / Time
Site:	University of Virginia
Issue date:	09/30/1988
From:	Mulder R VIRGINIA, UNIV. OF, CHARLOTTESVILLE, VA
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20155E177	List: ML20155E174 ML20155E198
References
NUDOCS 8810120164
Download: ML20155E198 (3)

Text

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UNIVERSITY OF VIRGINIA r ,g, , DEPART 5fENT OF NUCLEAR ENGINEERING AND ENGINEERING PIIYSICS NUCLEAR REACTOR FACILITY SCilOOL OF ENGINEERING AND APPLIED SCIENCE

( J CIIARLOTTESVILLE. VA 22901

, r Telephone: 801924 7136 September 30, 1988 U.S. Nuclear Regulatory Commission Document Control Dcsk Washington, D.C. 20555

Subject:

Change to UVAR TS 3.1.1, referring to Shutdown Margin calculation for tha University of Virginia Reactor (UVAR), Facility License No. R-66, Docket 50-62 Gentlemen:

The U.Va. Reactor Safety Committee today approved the text of a proposed wording change to UVAR Technical Specification 3.1.1. The current and proposed TS wording is presented in attachment, together with the basis for the change. We respectfully request NRC review and approval of this change in the Technical Specifications.

Yours"5 nb e'ly,

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Robert U. Mulder, Director U. of Virginia Reactor Facility Saern to aM ntw3t1 tehre me tYs- 3b-dry et aw JQ 19 _

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h LM1L3 b do J Net:q PJic My Comntasku Erpres en749, cc: USNRC Region II Administrator, Atlanta, Georgia Project Manager Mr. Al Adams, USNRC, Washington D.C.

E810120164 000930 DR ADOCK0500g2

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i PRESENT WORDING OF UVAR TECHNICAL SPECIFICATION 3.1.1

" 3.0 LIMITING CONDITIONS FOR OPERATION 3.1 Reactivity Aeolicabilityt These specifications apply to the reactivity d

condition of the reactor and the reactivity worths of control 3 rods and experiment.

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Obiectivest_ The objectives are to ensure that the reactor can be shut down at all times and that the safety limit will not be j exceeded.

Soecificationst The reactor shall not be operated at powers in excess of 1 kW unless the following conditions exists i

(1) The minimum shutdown margin provided by control rods, with secured experiments (see Section 1.0) in place and referred to

the cold, xenon-free condition with the highest worth control rod

fully withdrawn, is greater than 0.4% delta k/k.

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DEFINITION OF REGULATING ROD AND SHIM ROD LISTED l IN UVAR TECHNICAL SPECIFICATION 1.0 i

i Reculatina Rodt The regulating rod is a control rod of low

! reactivity worth fabricated from stainlesu steel and used to

! control reactor power. The rod may be controlled by the operator I with a manual switch or by an automatic controller.

Shin Rod! A shim rod is a control rod fabricated from borated I stainless steel, which is used to compensate for fuel hurnup,

! temperature, and poison effects. A shim rod is magnetically

{ coupled to its drive unit allowing it to perform the function of a safety rod when the magnet is de-energized.

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PROPOSED CHANGE TO UVAR TECHNICAL SPECIFICATION 3.1.1 l "

Snecifications: The reactor shall not be operated at powers in excess of 1 kW unless the following conditions exists (1) The minimum shutdown margin provided by shim rods, with secured experiments (see Section 1.0) in place and referred to the cold, xenon-froo condition with the highest worth shim rod fully withdrawn, is greator than 0.4% delta k/k.

) BASIS With the present TS wording, the shutdown margin for the

UVAR reactor may legally take into account the worth of the regulating rod, which is a "control rod" by definition. However, the regulating rod is not a scrammable rod, and therefore can't

, perform the function of a safety rod. Admittedly, the shutdown

margin should reflect the total scrammable negative reactivity j available for rapid reactor shutdown. The suggected wording

, change in TS 3.1.1, where the words "control rods" have been replaced with "shim rods", requires that the worth of the

.l regulating rod not be counted toward the shutdown margin, which l is the point of this technical specification.

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