PY-CEI-NRR-1213, Special Rept:On 900807,radiological Effluent Monitoring Instrumentation Inoperable for 72 H.Caused by Default Setpoints.New Microcomputer Chips Installed in All post-accident Radiation Monitors

Special Rept:On 900807,radiological Effluent Monitoring Instrumentation Inoperable for 72 H.Caused by Default Setpoints.New Microcomputer Chips Installed in All post-accident Radiation Monitors

ML20064A163
Person / Time
Site:	Perry
Issue date:	08/20/1990
From:	Lyster M CENTERIOR ENERGY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
PY-CEI-NRR-1213, NUDOCS 9008270133
Download: ML20064A163 (3)

Text

,

g l: PERRY NUCLEAR POWER PLANT Mail Address:

10 CENTER ROAD P.O. BOX 97 Michael D. Lyster

, PERRY, OHlf 44081 PERRY, OHIO 44081 Ve6 President Nuclear (216)259T,37 August 20, 1990 PY-CEI/NP.R-1213 L t

U.S. Nuclear Regulatory Commission Document Control Desk Washington, D. C. 20555 Perry Nuclear Power Plant Docket No. 50-440 Radiological Effluent '

Monitoring Inoperability Special Report

Dear Sir:

Attached is a Special Report concerning inoperable Radiological Effluent Monitoring Instrumentation. This report satisfies the conditions of Perry Technical Specifications 3.3.7.5 and 6.9.2.

If you have'any questions, please feel free to call.

Sincerely I ~l AN Michael D. Lyster MDL:NJL:njc Attachment cc: KRR Project Manager Sr. Resident Inspector USNRC Region III Director, Office of Resource Management 00003 9008270133 900820 "

PDR S

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.' Attechmnt 1 PY-CEI/NRR-1213b

. Page 1 of 2 Special Report Radiological Effluent Monitoring Inoperability On August 4, 1990 at 1049 hours0.0121 days <br />0.291 hours <br />0.00173 weeks <br />3.991445e-4 months <br />, the Unit 2 Plant Vent Post-Accident radiation moniter 2D19-K300, was declared inoperable to facilitate performance of the calibration procedure. Technical Specification Action Statement 3.3.7.5 requires that if the instrument remains inoperable for more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, a special report be submitted to the Commission within 14 days of the event. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> time limit was exceeded on August 7, 1990 at 1049 hours0.0121 days <br />0.291 hours <br />0.00173 weeks <br />3.991445e-4 months <br />. In accordance with Technical Specifications, preplanned alternate monitoring methods were initiated at that time. All aspects of Technical Specifications were met.

The Unit 2 plant vent monitor, 2D19-K300, is a Kaman Post-Accident Digital radiation monitor. It monitors effluent airborne radiation from the Unit 1 Control Complex and Intermediate Building during accident conditions. W sample is drawn from the normal range Plant Radiation Monitoring (D17) system isokinetic sampler. The sample passes through 1 of 3 particulate / iodine channels and then through a sample pump and gas sample chamber. The gas sample chamber has two detectors, one for intermediate range and one for the high range. Signals from the sample skid are then sent to a microcomputer where they are processed. The signals are finally routed to an indication and control module in the Unit 2 control room with an alarm feature provided in the Unit 1 control room.

During the calibration procedure mentioned above, an " Equipment Fail" alarm was received on the indication and control module and would not clear. Also, process flow testing under that instruction showed the control room read-out module was indicating lov flow. A work order was written and troubleshooting began immediately. Troubleshooting on August 4, 1990 did not yield any conclusive results; ho,iever, the

" Equipment Fail" alarm had cleared on its own. Problems with flow calibration vere still present.

The investigation resumed on August 6, as the setpoints stored in memory of the microcomputer vere found to b- default setpoints.

It appeared as though the microcomputer reverted to its default setpoints which do not match the actual setpoints used at Perry.

It is believed that the unit reverted to the default parameters during the calibration procedure when it was shut off to connect test equipment. The battery backup power did not engage properly, allowing the unit to revert to the default setpoints.

vf* Attcch::nt 1 .

.. PY-CEI/NRR-1213 L '

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,, Page 2 of 2 When the erroneous default parameters stored in memory replaced the proper setpoints, the unit behaved erratically, which is why the " Equipment Fail" alarm would not clear. Correspondence with the vendor has yielded some possible causes for improper ,

operation of the battery backup. Those possibilities were investigated during troubleshooting. However, a definite root cause has not been identified yet. Perry is monitoring the unit for this problem.

The lov flow indications are considered a secondary concern since they do not affect the operability of this unit. Troubleshooting-verified flow through this unit was satisfactory. Sample flow was the only parameter shown on the indication module in the control room that was wrong. A ptoblem with the power supply to the mass flow meter transducer was the cause of this condition.

The power supply was replaced on August 10,_1990.

Unfortunately, troubleshooting did not uncover the root cause for the battery backup or flow indication condition before the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Limiting condition of Operation (LCO) was exceeded.

-Investigation vill continue into the root cause of the battery backup question. Additionally, new microcomputer memory chips vill be installed in all Post-Accident radiation monitors. The '

new chips vill contain default parameters that vill match the parameters used at Perry. If a unit reverts to its default setpoints again, for any reason, no change in operation should occur. The Post-Accident radiation monitor was restored to operable status on August 16, 1990. The battery backup circuit has been tested numerous times and is working properly. Further ,

troubleshooting at this time does not appear to be productive ,

regarding the battery backup circuit.

The vendor has received approval from Perry Nuclear Assurance -

Department to forward the microcomputer memory chips which contain the new default setpoints. As soon as these arrive on site, they will be installed. Pending installation of the new chips, the unit vill be monitored closely to ensure the battery backup does not fail its intended function. Currently, the expected completion date is August 31, 1990.

NJC/ CODED /3706 l

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