ML19319D895
| ML19319D895 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry, Rancho Seco  |
| Issue date: | 11/25/1977 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19319D888 | List: |
| References | |
| NUDOCS 8003270553 | |
| Download: ML19319D895 (5) | |
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UNITED STATES
-4 NUCLEAR REGULATORY COMMisslON f'C WASHINGTON, D. C. 20555
%,.., j SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION C
SUPPORTING AMENDMENT NO.
TO FACILITY OPERATING LICENSE NO. DPR-54 el SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING STATION
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DOCKET NO. 50-312 INTRODUCTION Following a fire at the Browns Ferry Nuclear Station in March 1975, we initiated an evaluation of the need for improving the fire protection programs at sil licensed nuclear power plants.
As part of this continu-ing evaluation, in February 1976 we published a report entitled
" Recommendations Related to Browns Ferry Fire", NUREG-0050.' This report recommended that improvenents in the areas of fire prevention and fire control be made in most existing facilities and that consideration be given to design features that would increase tne ability of nuclear facilities to witnstand fires ithout the loss' of important functions.
To implement the report's recommendations, the NRC initiated a program for reevaluation of the fire protection programs at all licensed nuclear power stations and for a comprehensive review of all new license applications.
We have issued new guicelines for fire protection programs in nuclear power plants.
These guidelines reflect the recommendations in NUREG-0050.
These guidelines are contained in the following documents:
" Standard Review Plan for the Review of Safety. Analysis Reports for Nuclear Power Plants," NUREG-75/087, Section 9.5.1, " Fire Protection," May 1976, which includes " Guidelines for Fire Protection for Nuclear Power Plants," (BTP APCSB 9.5-1), May 1,1976.
" Guidelines for Fire' Protection for Nuclear Power Plants"(App'ndix e
A to BTP APCSB-9.5-1), August 23, 1976.
' "Supplenentary Guid3n'ce on Infor5ation Needed for Fire 'Pr tection '
Program Evaluation," September 30, 1976.
" Nuclear Plant Fire Protection Functional Responsibilities, Administrative Controls and Quality Assurance," June 14, 1977.
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' Sacramento Municipal Utility District (licensee) has submitted a description of the fire protection program for the Rancho Seco Nuclear Generating Station by letter dated August 1,1977.
This program is under detailed review by the NRC.
In the interim, until we complete our detailed review, we have concluded that it is appropriate to amend the facility license by incorporating into the Technical Specifications operability and surveillance requirements for the existing fire pro-tection equipment and systems.
In addition, the amendment would include administrative requirements for the implementation of the fire protection program.
By letter dated September 30, 1976, we requested the lie.ensee to submit Technical Specifications for the presently-installed fire protection equipment at this facility.
By letter of December 2, 1976, we issued sample Technical Specifications and reiterated that these specifications were for existing systems only.
Subsequently, the licensee proposed Technical Specifications by letter dated January 10, 1977.
Based on our review and consideration of that response and the responses of other licensees, we modified certain action statements and surveillance frequencies in order to provide more appropriate and consistent specifications which we forwarded to the licensee by letter of June 16, 1977.
That letter also requested sub-mittal of apprupriately revised specifications..
, 1977.
We have reviewed The licensee responded by letter dated August 1, ions where necessary to the licensee's response and have made modificat assure confonnance to the fullest extent practicable with our require-ments as set forth in the sample Technical Specifications pending com-pletion of our ongoir.g detailed review of fire protection at this facility.
DISCUSSION Afl0 EVALUATION
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The guidelines for Technical Specifications that we developed and sent to all licensees are based on assuring that the fire protection equipment currently installed for the protection of safety related areas of the-plant is operable.
This assurance is obtained by requiring periodic surveillance of the equipment and by requiring certain corrective actions to be taken if the limiting conditions for operation cannot be met.
These guidelines also include administrative features for the overall fire protection program such as interim fire brigade requirements, training, precedures, management review and periodic independent fire protection and loss prevention program inspections.
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. The equipment and components existing at this facility and included in the scope of these Technical Specification requirements are fire detectors, the fire suppression systems, the hose stations, and penetration fire barriers for piping and cabling pene trations.
Operability of the fire detection instrumentation provides warning cabability for the prompt detection of fires, to reduce the potential for damage to safety related equipment by allowing rapid response of fire suppression systems.
In the event that the minimum coverage of fire detectors cannot be met, hourly fire patrols are required in the affected area until the inoperable instrumentation is restored to operability.
The operability of the fire suppression systems provides capability to confine and extinguish fires.
In the event that portions of the fire suppression systems are inoperable, alternate backup fire fighting equipment is required to be made available in the affected areas until the inoperable equipment is returned to service.
In the event that the fire suppression water system becomes inoperable, a backup fire protection water system is required within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and a report to the NRC is required within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to provide for prompt evaluation of the acceptability of the corrective measures for adequate fire suppression capability.
The functional integrity of the penetration fire barriers provides protection to confine or retard fires from spreading to adjacent portions of the facility.
During periods of time.when a fire barrier.is not functional, a continuous fire watch is required to be maintained in the vicinity of the affected barrier to provide fire prevention methods a'nd Fmpt detection and suppression
.f.n;.the e. vent of a fire.
We have reviewed the licensee's proposed interim Technical Specifi-catiens against our equirements as implemented in the sample Technical Specifications.
We have made some ~ modifications to the Specifications that were proposed by the licensee in order to make them conform to our requirements. One of the proposed specifications that we changed involves the minimum size of the on-site fire brigade.
In our previous sample Technical Specifications we did not identify the number of members on a fire brigade that we would find acceptable.
We have now concluded that minimum number fJr d typical commercial nuclear power plant to be five (5).
The bas'.s for this conclusion is presented in an attachment to this SER entitled " Staff Position Minimum Fire Brigade Shift Size."
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. In the report of the Special Review Group on the Browns Ferry Fire
'NUREG-0050) dated February 1976, consideration of the safety of operation of all operating nuclear power plants pending the completion of our detailed fire protection evaluation was presented.
The follcwing quotations frcm the report summarize the basis for our conclusion that the operation of the plants, until we complete our review, does.not present an undue risk to the health and safety of the public.
"A probability assessment of public safety or risk in quantitative tems is given in the Reactor Safety Study.
(WASH-1400). As the result of the calculation based c9 the Browns Ferry fire, the study concludes that the potential for a significant release of radioactivity from such a fire is about 20% of that calculated from all other causes analyzed. This indicates that predicted potential accident risks frem all causes were not greatly affected by gonsideration of the Browns Ferry fire.
This is one of the reasons that urgent action in regard to reducing risks due to potential fires is not required.
'The study.(WASH-1400) also points out that 'rather straight-forward neasures, such as may already exist at other nu'elear plants, can significantly reduce the likelf. hood of a potential core melt accident that might result from a large fire.' The Review Group agrees.
" Fires occur rather frequently; however, fires involving equipment unavailability ccmparable to the Browns Ferry fire are quite infrequent (see Section 3.3 [of NUREG-0050]).
The Review Group believes that steps already taken since March 1975 (see Section 3.3.2) have reduced this frequency significantly.
" Based on its review of the events transpiring before, during and af ter the Browns Ferry fire, the Review Grac; cor.cludes that the probability of disruotive fires of the magnitude of the Browns Ferry event is small, and that there is no need to restrict operation of nuclear power plants for public safety.
However, it is clear th'at much can and should be done to reouce even further the likelihood of disabling fires and to improve. assurance of rapid extinguishment of fires that occur.
Consideration should be given also to features that would increase further the ability of nuclear facilities to withstand large fires without loss of important functions should such fires occur."
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. Subsequent to the Browns Ferry fire and prior to the Special Review Group's investigation, the Office of Inspection and Enforcement took steps with regard to fire protection.
Special bulletins were sent to all licensees of operating power reactors on liarch 24,1975, and April 3,1975, directing the imposition of certain controls over fire ignition sources, a review of procedures for controlling maintenance and modifications that might affect fire safety, a review of emergency procedures for alternate shutdown and cooling methods, and a review of flammability of materials used in floor and wall penetration seals.
Special inspections covering the installation of fire stops in electrical cables and in penetration seals were ccmpleted 'at all operating power reactors in April and May 1975. Ins.pection findings which reflected non-compliance with NRC requirements resulted in requiring corrective action by licensees. Follow-up inspections have confirmed that licensees are taking the required corrective actions and that administrative control procedures are in place.
Since these inspection activities and the subsequent Special Review Group recommendations in the 1975 to 1976 time period, there has been no new information to alter the conclusions of the; Special Review Group, and the ongoing fire protection program flowing from those conclusions is still adequate.
Therefore, we have found these specifications acceptable on an interim ba' sis until such tim,e that our everall review is complete, required equipment is installed and operable, and final specifications have been developed and issued.
ENVIRONMENTAL CONSIDERATION We have determined that the amendment does not authorize ~a change in effluent types or total amounts nor an increase in power level and'will not result in any significant environmental impact.
Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the stand-point of environmental impact and, pursuant to 10 CFR 551.5(d)(4),
that an enviro ~nmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
. CONCLUSION
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We hav'e concluded, based on the considerations discussed above,'
that:
(1) because the amendment does not involve a significant in-crease in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety
. margin, the amendment does not involve a significant hazards consider-ation, (2) there is reasonable assurarice that the health and safety of the public will not be endangered by operation in the proposed manner; and (3) such activities will 'e conducted in compliance c
with the Comissio.i's regulations and the issuance of this amendment will not be inimical to the cormon defense and security or to the health and safety of the public.
nate: goyder 25, 1977
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