U-600672, Advises That Control Logic for Operation of Four 36-inch Isolation Valves Does Not Meet NUREG-0737,Item II.E.4.2 Requirement That Reopening of Containment Isolation Valves Require Deliberate Operator Action.Plant Mod Pending

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Advises That Control Logic for Operation of Four 36-inch Isolation Valves Does Not Meet NUREG-0737,Item II.E.4.2 Requirement That Reopening of Containment Isolation Valves Require Deliberate Operator Action.Plant Mod Pending
ML20212E606
Person / Time
Site: Clinton Constellation icon.png
Issue date: 08/08/1986
From: Spangenberg F
ILLINOIS POWER CO.
To: Butler W
Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.E.4.2, TASK-TM U-600672, NUDOCS 8608130099
Download: ML20212E606 (2)


Text

U-600672 L30-86( 08- 08)-L w

s 1A.120

/LLINDIS POWER OOMPANY CLINTON POWER STATION, P.o. BOX 678. CLINToN. ILLINOIS 61727 August 8, 1986 Director of Nuclear Reactor Regulation Attention: Dr. W. R. Butler, Director BWR Project Directorate No. 4 Division of BWR Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Clinton Power Station (CPS)

Containment Isolation for 36" Ventilation Valves

Dear Dr. Butler:

This letter is to inform you of an existing design condition that does not agree with the CPS Final Safety Analysis Report (FSAR) description of a requirement in NUREG-0737 " Clarification of TMI Action Plan Requirements." This design condition has been evaluated and determined to not have an adverse effect on the safe operation of the plant. Nevertheless, a design modification is being performed and will be completed prior to the CPS Hearup milestone so that the design will agree with the FSAR description.

In NUREG-0737, Item II.E.4.2 " Containment Isolation Dependability,"

there is a requirement for control of automatic isolation valves such that resetting the isolation signal will not result in the automatic reopening of containment isolation valves. Reopening of containment isolation valves shall require deliberate operator action. Illinois Power (IP) responded to this requirement in FSAR Appendix D with the commitment that CPS control systems for containment isolation valves which automatically isolate do not permit automatic reopening of these valves when the isolation signal is reset. It is also stated that the normal control switches for these valves must be manipulated individually subsequent to the resetting of the isolation signal to reopen the valves.

During startup testing of the Containment Building HVAC (VR) and the Drywell Purge (VQ) systems, it was discovered that the control logic for the operation of four (4) 36" isolation valves does not meet the above requirement. Control switches for these valves should be manipulated individually subsequent to the resetting of the high radiation isolation signal. Presently, all four valves are allowed to re-open upon the manipulation of the. bypass switches (one switch for each divisional pair of valves) of the purge system; i.e. the seal-in circuits for high radiation signal on these four (4) isolation valves are located at the bypass switches rather than the individual valve controls.

8608130099 860808 PDR ADOCK 05000461

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A CPS plant modification is in progress (PM #VQ-02) that will correct the control circuits for these valves to conform to the specific description in the FSAR. A seal-in circuit will be placed at each individual valve control and each valve control will have to be individually manipulated in order to open the valve after a high radiation isolation signal. The scheduled completion of this plant modification is prior to the CPS Heatup milestone.

Operation of CPS up to the Heatup milestone is justified because the valves will be locked closed until the modification is installed.

The valves are not required for fuel loading activities.

Please contact me if you have any questions on the foregoing information.

Sincerely yours, F. A. Spang berg Manager - Licensing and Safety TLR/ckc cc: B. L. Siegel, NRC Clinton Licensing Project Manager NRC Resident Office Illinois Department of Nuclear Safety Regional Administrator, Region III, USNRC