U-601258, Special Rept:On 880803,accident Monitoring Instrumentation for HVAC Stack Declared Inoperable for More That 72 H.Caused by Underway Work to Perform Routine Channel Calibr.Plant Condition Rept Initiated

Special Rept:On 880803,accident Monitoring Instrumentation for HVAC Stack Declared Inoperable for More That 72 H.Caused by Underway Work to Perform Routine Channel Calibr.Plant Condition Rept Initiated

ML20151Z371
Person / Time
Site:	Clinton
Issue date:	08/22/1988
From:	Holtzscher D ILLINOIS POWER CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
U-601258, NUDOCS 8808290308
Download: ML20151Z371 (2)

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U-601258 L30-88(08-E2 )-LP 8E.110 ILLINDIS POWER 00MPANY cuNioN Pe%ER STATLON. P.o. 801 678. CLINToN, ILL oi g727 10CFR50.36 August 22, 1938 Docket No. 50-461 Mr. A. B. Davis

1. 8 \

Regional Administrator Re.,lon III 2h.

U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn,_ Illinois 60137-

Subject:

Special Report: Extended Inoperability of the HVAC Stack High Range Radioactivity Monitor

Dear Mr. Davis:

CPS Technical Specification 3.3.7.5 (Accident Monitoring Instrumentation) establishes operability requirements for the HVAC Stack High Range Radioactivity Monitor, and in addition, prescribes the action to be taken if the monitor becomes inoperable. On August 3, 1988, this monitor was declared inoperable. Although oilores to repair the monitor began immediately, the monitor was not returned to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as required by ACTION 81 of Table 3.3.7.541 in the Clinton Technical Specifications.

ACTION 81 states that if the monitor is not restored to operable

~ otat>2s within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, a Special Report must be prepared and submitted to the Commiscion pursuant to Specification 6.9.2 ("Special Reports")

within 14 days following the event. This report must outline the action taken, the cause of the inoperability and the plans and schedule for restoring the system to operable status. This report is therefore submitted accordingly. The Event Summary that follows provides the required information.

Event Summary Although preparatory work had begun the evening of 8/2/88, the monitor was initially declared inoperable at 1020 during the day shift on .tugust 3, 1988 as work was underway to perform the routine channel calibration. (This calibration is performed at least once every 18 months.) The channel calibration, which is quite extensive due to the complexity of this monitor,* usually tat's several shifts to complete.

• The HVAC monitor has six channels associated with it; other appurtenances include a flow switch and flow measurement instrumentation, computer po'.nts providing signals to the central control terminals and the safety parameter display 9, gp 7

system, and the associated detectors. A complete calibratin necessitates taking the monitor out-of-service even for work ,

performed on the non-Technical Specification related portions o' the monitor.

8808290308 880822 AUG 251988' PDR ADOCK 05000461 S PDC

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U- 601258 L30-88 ( 08- 23 -LP 8E.110 As testing progressed, a number of problems were encountered which delayed satisfactory completion of the calibration:

(1) The surveillance procedure used to perform the calibration had been completely revised earlier this year. As the calibration was performed, some technical problems with the new procedure were discovered which necessitated minor but tims-consuming changes.

(2) Problems with computer points associated with the monitor were encountered. The additional adjustments (to the analog-to-digital converter cards) necessitated keeping the monitor out-of-service longer.

(3) The acceptance criteria for the calibration of the detector could not be met. Time was lost while investigating the problem. It was eventually determined that the detector was bad and had to be replaced.

These problems are not unusual, but when incurred together, they caused the time needed to complete the calibration to exceed the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowed for the monitor to be out-of-service.

The monitor was restored to operable status during the day shift on 8/6/88. The total time taken to restore it to operable status was approximately 77 hours8.912037e-4 days <br />0.0214 hours <br />1.273148e-4 weeks <br />2.92985e-5 months <br /> (5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> in excess of the allowed out-of-sertice time).

A plant condition report has been initiated to further investigate the calibration delays and to determine what can be done to prevent recurrence of this condition. It should be noted that the calibration could be performed during shutdown conditions when the monitor is not required to be operable. The investigation required for the plant condition report should determine whether or not the calibration schedule should be adjusted so that the calibration coincides with the refueling outages.

If you have any comments or questions regarding this event, please contact me.

Sincerely yours, M

D. L. Holtzscher Acting Manager - Licensing and Safety TBE/ckc cc: NRC Clinton Licensing Project Manager NRC Resident Office Illinois Department of Nuclear Safety J