ML20030E235
| ML20030E235 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/01/1981 |
| From: | Haynes J SOUTHERN CALIFORNIA EDISON CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| IEB-79-18, NUDOCS 8109180245 | |
| Download: ML20030E235 (2) | |
Text
[e Bulletin No. 79-18 Docket No. 50-206 Southern California Edison Company h5 P O BOX SOO 2244 W ALNUT GROVE AVENUE ROSE M E AD. C AllFORNI A 91770 J'l',',[ ~l,
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September 1, 1981 t
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-3 U. S. Nuclear Regulatory Commission 6
bEp Office of Inspection and Enforcement Region V e
1990 North California Boulevard D
Y Suite 202, Walnut Creek Plaza Y
Walnut Creek, California 94596 m
Attention: Mr. R. H. Engelken, Director Docket No. 50-206 San Oaofre-Unit 1
Dear Sir:
IE Bulletin 79-18 Audibility Problems Encountered On Evacuation of Personnel From High Noise Areas
References:
1.
Letter, J. T. Head (SCE) to R. H. Engelken (NRC) dated September 19, 1979.
2.
Letter, J. T. Head (SCE) to R. H. Engelken (NRC) dated December 4,1979.
3.
Letter, J. G. Haynes (SCE) to R. H. Engelken (NRC) dated June 15, 1981.
The referenced letters provided our response to the subject IE Bulletin and documented the results of investigations into the audibility of the In-Plant Paging (IPPS), Immediate Evacuation Signal, and Area Radiation Monitoring ( ARMS) Systems.
Signal audibility was determined to be insufficier.t in several plant locations and extensive modifications to these systems were Ierformed during the recent refueling and maintenance outage.
Upon rt uurn to service, the atove mentioned modifications were complete. However as described in Reference 3, in os der to assure that the audibility of the modified systems meets design specification, plant operation at or near full load during systems testing was necessary to establish maximum background noise levels. Thus, a schedule was given in Reference 3 to complete testing of the identified systems within 30 days of the unit return to sustained full load operation. The testing is complete.
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' U. S. NUCLEAR REGULATORY COMMISSION R. H. ENGELKEN, DIRECTOR IE BULLETIN 79-18 PAGE 2 Testing of the Immediate Evacuation Signal for its audibility in the plant will be completed concurrent with testing of the surrounding off site sirens.
Functional testing of the Area Radiation Monitoring System (ARMS) alarms is complete. Acceptance criteria for each area tested required that the signal to noise differential (in dB) exceed a value that is a function of the frequency of the alarm signal.
In each area where an audible ARMS alarm is relied upon for evacuation notification the measured signal to noise differential exceeded that which was required. A visual alarm has been installed in the charging pump room where background noise levels with the pumps in operation effectively eliminates the possibility of using audible alarms.
sting of the In Plant Paging System in those areas of the plant 7
where modificacions were nade to correct deficiencies as described in Reference 1 is essentially complete. Acceptance of each area tested is based on the Speech Transmission Index Method which utilizes measured acoustic and geometric parameters to calculate Sentence Inteligibility (SI) in percent.
An area was accepted if the SI of a recorded message transmitted over the IPPS was 96% or better. Adjustments and repairs have been made to the IPPS components; however, analysis to date of the final test data indicates that some areas still have minimal or inadequate coverage. These areas are currently being evaluated to determine the most practical solution to the inaudibility problems.
In areas where additional speaker installation is not feasible, visual alarms may be used or administrative measures taken to ensure personnel evacuation is effected. Administrative measures and temporary speaker installations are being evaluated to cover these areas until the permanent corrective measures can be implemented.
We will advise you further of our intentions by October 15, 1981.
Please notify me if you have any questions concerning this matter.
Sincerel,
NT cc:
U. S. Nuclear Regulatory Commission Division of Reactor Operations Inspection L. F. Miller - USNRC Resident Inspector