ML20043G197

LER 90-006-00:on 900517,electrical Spike on Radiation Monitor R-25 Caused auto-start of Spent Fuel Pool Special Ventilation Sys.Caused by Procedural Inadequacy.Request for Training Issued Re Basics of Procedure writing.W/900615 Ltr

ML20043G197
Person / Time
Site:	Prairie Island
Issue date:	06/15/1990
From:	Hunstad A, Parker T NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-006, LER-90-6, NUDOCS 9006200028
Download: ML20043G197 (4)

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Northem States Poww Company 414 Nicollet Mall Minneapolis, Minnesota 554011927 1 Telephone (612) 330-5500 June 15, 1990 10 CFR Part 50 I Section 50.73 ,

Director of Nuclear Reactor Regulation ,

U S Nuclear Regulatory Commis.sion '

Attn: Document Control Desk '

Washington, DC 20555 PRAIRIE ISLAND NUCLEAR CENERATING PLANT Docket Nos. 50-282 License Nos. DPR 42 50 306 DRP-60  ;

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Auto start of Spent Fuel Pool Special Ventilation j System Due to Procedure Inndeaunev +

o The Licensee Event Report for this occurrence is attached. l l

This event was reported via the Emergency Notification System in accordance with .

j 10 CFR Part 50, Section 50.72, on May 17, 1990. Please contact us if you  :

require additional information related to this-event.-

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0 p Thomas M Parker -

1 Manager Nuclear Support Services

-j c: Regional Administrator Region III, NRC NRR' Project Manager, NRC Senior Resident Inspector, NRC MPCA Attn: Dr J W Ferman

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On May 17, 1990, both units were operating at 100t power. k' hen an 160 technician had completed work on radiation monitor channel R 25. he restored the channel to normal and called for a radiation protection specialist to test the monitor with a test source. Channel R 25 was placed in reset to prevent actuation of the Spent Fuel Pool Special Ventilatior System and the monitor was then tested, k' hen monitor R 25 was tested with the test source nearby redundant monitor R 31 responded to the rediation source and actuated No. 122 Spent Fuel Pool Special Ventil: tivi. "ystem. The control room operators and the technicians realized immediately what had happened; the test source was removed, the monitor was reset. Spent Fuel Pool Special Ventilation System was shut down and the Spent Fuel Pool Normal Ventilation System was restored. Cause of the event was procedure inadequacy. The author of the work procedure had considered the effect of the monitor bugging operation, but had written the caution as a note instead of a procedural signoff step. As a result. the technician did not disable the redundant monitor before the bugging operation.

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On May 14, 1990, an electrical spike on radiation monitor R 25 (EIIS Component identifier MON) caused an auto start of the Spent Fuel Pool Special Ventilation System which was reported in Prairie Island Unit 1 LER 90 05. R 25 was removed from service and a work request was initiated to investigate the cause of the spiking and to make any necessary repairs. As part of the work request preparation process a work procedure was prepared by the responsible engineer for the repair, testing and return to service of R 25. Work was started on radiation monitor channel R 25 on May 16, 1990, to try to determine and correct the cause of the spiking.

On May 17, 1990, both units were operating at 100% power. The 160 technician completed work on R 25 on May 17th. The 16C technician restored the channel to normal and called for a radiation protection specialist to test the monitor with a test source. Channel R 25 was placed in reset to prevent actuation of the Spent Fuel Pool Special Ventilation System and the monitor was then tested.

When monitor R 25 was tested with the test source, nearby redundant monitor R 31 responded to the radiation source and actuated No. 122 Spent Fuel Pool Special Ventilation System at 1029. This was a non ESF actuation of an ESF system.

The control room operators and the technicians realized immediately what had happened; the test source was removed, monitor R-31 was reset, No. 122 Spent Fuel Fool Special Ventilation System was shut down and the Spent Fuel Pool Normal Ventilation System was restored.

CAUSE OF THE EVENT The cause of the event was an inadequacy in the work request work procedure.

The author of the work procedure had considered the effect of testing R 25 with '

the test source on the operation of R 31 and the No. 122 Spent Fuel Pool Special Ventilation System. However, the requirement to place channel R 31 in reset was placed in the work procedure as a note rather than a procedural signoff step.

The 16C technician missed the note on placing R 31 in reset and as a result, did not disable redundant monitor R 31 before testing R 25 with the test source.

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ANALYSIS OF THE EVENT '

The functional response of the auto start actuation of the Spent Fuel Pool J Special Exhaust System was according to design, which is to deactivate the Spent  ;

Fuel Pool Normal Supply and Exhaust Fans and actuate the Spent Fuel Peol Special Exhaust Fans. The Spent Fuel Pool Special Ventilation System is used to decrease radiological impact of a radiological release in the Spent Fuel Pool through increased filtration and monitoring of the air in the ventilation system. Since this event was not triggered by radiological events, there were no radiological concerns and there was no effect on the health and safety of the public. -

CpRRECTIVE ACTION A Request for Training has been issued to include basics of procedure writing in a future engineer and technical staff training session.

FAILED COMPONENT IDENTIFICATION None. The equipment operated as designed.

PREVIOUS SIMILAR EVENTS There have been no previous similar events reported at Prairie Island.

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