ML18029A493
| ML18029A493 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 04/05/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18029A492 | List: |
| References | |
| NUDOCS 8504250043 | |
| Download: ML18029A493 (3) | |
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/J +y*y0 UNITED STATES NUCLEAR REGULATORY COMIVIISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.
116 TO FACILITY OPERATING LICENSE NO.
DPR-33 AMENDMENT NO.
111 TO FACILITY OPERATING LICENSE NO.
DPR-52 AMENDMENT NO.
86 TO FACILITY OPERATING LICENSE NO.
DPR-68 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT, UNITS I, 2 AND 3 DOCKET NOS. 50-259, 50-260 AND 50-296 1.0 Introduction By letter dated October 19, 1984 the Tennessee Valley Authority (the licensee/TVA) requested amendments to Facility Operating License Nos.
DPR-33, DPR-52 and DPR-68 for the Browns Ferry Nuclear Plant, Units I, 2 and 3.
The amendments would delete operability and surveillance requirements for the secondary containment static pressure limiting system.
As stated in Final Safety Analysis Report (FSAR) Section 5.3.3.7, the function of the system is to prevent the standby gas treatment system (SGTS) blowers, which have an excess
- capacity, from creating a large negative pressure in the building and causing difficulty in the opening of doors.
The system is in the Technical Specifications because malfunction could cause loss of secondary containment integrity.
2.0 Evaluation The static pressure limiting system is a subsystem of the standby gas treatment system.
According to design calculations, using the standby gas treatment system to exhaust less than four reactor building zones will result in an exhaust rate greater than the infiltration rate.
The secondary containment wall area for an individually isolated zone is less than that of the total reactor building, which results in proportionallg smaller leakage rates.
Consequently, negative pressure within any zone during single zone isolation operation could be much greater than 0.25 inch of water
- gauge, creating a problem with door operation.
The static pressure limiting system bleeds outside air into each zone of the reactor building through vacuum relief lines to prevent outside pressure exceeding the pressure inside the building by more than 0.50 inch water gauge.
Each reactor zone is provided with a separate independent vacuum relief line and the refueling zone is provided with two separate vacuum relief lines.
The vacuum relief lines are located on the ventilation air supply duct downstream of the containment isolation valves.
Each vacuum relief line contains two electrically operated, low-leakage dampers mounted in series.
One of the dampers has two positions while the other is the modulating type.
Upon zone isolation the two-position damper is automatically 850 2 oo ~ o500025 p
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The other damper modulates automatically to limit the pressure difference between the reactor building and the outside to not exceed 0.50 inch water gauge and is of a fails-as-is design.
The licensee proposes to permanently block-off the vacuum relief lines.
This will ensure that secondary containment integrity is not threatened by leakage through these lines in the event of system failure.
The licensee further states that operating experience has shown that the static pressure limiting system is not needed to limit building negative pressure as originally predicted.
Based on our evaluation of the information presented by the licensee, we find that the static pressure limiting system is not needed to limit building negative pressure and that elimination of the static pressure limiting system will not threaten the integrity of the secondary containment.
We, therefore, conclude that the proposed change to the Technical Specifications is acceptable.
3.0 Environmental Considerations The amendments involve a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and in a surveillance requirement.
The staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration and there has been no public comment on such finding.
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
4.0 Conclusion We have concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
W. Long, F. Eltawila Dated: April 5, 1985