ML20151A277

SER Supporting Util Actions to Prevent Failure of Ammonia Tanks Which May Result in Incapacitation of Control Room & Technical Support Ctr Personnel

ML20151A277
Person / Time
Site:	Rancho Seco
Issue date:	07/13/1988
From:	NRC
To:
Shared Package
ML20151A274	List: ML20151A270 ML20151A277
References
NUDOCS 8807190315
Download: ML20151A277 (2)

Text

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[ g NUCLEAR REGULATORY COMMISSION l

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l SAFETY EVALUATION REPORT RANCHO SEC0 CONTROL ROOM AND TECHNICAL SUPPORT CENTER HABITABILITY RELATIVE TO POTENTIAL ACCIDENTAL AMMONIA SPILLS

1.0 INTRODUCTION

The Radiation Protection Branch (PRPB) was requested to evaluate the habitability of the Rancho Seco control room / technical support center (CR/TSC) relative to potential ammonia tank rupture accidental releases. The staff reviewed the licensee's submittal of May 19, 1988 and performed independent analyses of the potential consequences in the CR/TSC as a result of accidental amonia releases.

2.0 DISCUSSION The requirements for the protection of the CR/TSC personnel under accidental chemical release conditions are specified in GDC-19. The guidance for the bases of acceptance of the GDC-19 requirements are provided in SRP Section 6.4 and Regulatory Guides 1.78 and 1.95.

By letter dated May 19, 1988, the licensee proposed to reduce the concentration of aqueous amonia stored onsite from 28% to 20%. The aqueous amonia, which is stored in a 20,000 gallon tank, has been identified as potentially hazardous to CR/TSC habitability. This amonia tank is approximately 152 meters from the normal operation CR/TSC intake. The CR/TSC habitability in case of accidental amonia release depends upon odor detection of ammonia by the CR/TSC personnel and the donning of self-contained respiratory equipment within 2 minutes of detection. The licensee presented the analyses of the potential consequences of accidental amonia releases on CR/TSC habitability. The staff evaluated the licensee estimates and made its own independent analyses.

The NRC staff has evaluated the habitability of the CR/TSC with respect to a failure of the 20,000 gallon tank of 20% anhydrous amonia, located 152 meters from the CR/TSC intake, in accordance with SRP 6.4 and Regulatory Guide 1.78. Since there is no provision for monitoring for amonia with automatic isolation of the normal ventilation system, the t

licensee is depending on the ability of operators to detect the amonia odor and don self-contained breathing apparatus prior to incapacitation.

Regulatory Guide 1.78 suggests that the operator is adequately protected if it can be demonstrated that a chemical in the air can be detected by the operator and that he can don a self-contained breathing appratus in 8807190315 880713 PDR ADOCK 05000312 p PDC

-2 less than two minutes and not be exposed to an incapacitating concentration of that chemical "protective action limit" in the two minute period. For amonia, the normal odor threshold is approximately 47 ppm. The "protective action limit" for amonia, from Regulatory Guide 1.78, is 100 ppm.

Utilizing the conservative assumptions of Regulatory Guide 1.78, the staff has analyzed the consequences of a rupture of the 20,000 gallon tank of 20% anhydrous amonia to the CR/TSC personnel. Based upon this analysis, the staff finds that there are more than two minutes available between the time when 47 ppm and 100 ppm of amonia would be present in the CR/TSC.

The licensee has provided several analyses of the consequences in the CR/TSC of the amonia tank failure. Based upon these analyses the licensee also concludes that the "protective action limits" are not exceeded in the CR/TSC within two minutes after initial odor detection by CR/TSC personnel.

Based upon'our own independent analyses and our review of the licensee analyses, the staff concludes that the CR/TSC personnel are adequately protected from the potential effects of a major failure of the amonia tank.

3.0 CONCLUSION

Based upon the foregoing, the NRC staff finds that the licensee has demonstrated that the CR/TSC habitability systems will adequately protect the CR/TSC operators from the consequences of a major ammonia tank failure in accordance with the requirements on GDC-19.

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