ML20072P954
| ML20072P954 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 11/16/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072P952 | List: |
| References | |
| NUDOCS 9011290341 | |
| Download: ML20072P954 (4) | |
Text
UNITED STATES 3
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SAFETY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 156 TO FACILITY OPERATING LICENSE NO. DPR-66 DUQUESNE LIGHT COMPANY OHIO EDISON COMPANY PENNSYLVANIA POWER COMPANY BEAVER VALLEY POWER STATION, UNIT NO. 1 DOCKET NO. 50-334
1.0 INTRODUCTION
By letter dated October 25, 1990, Duquesne Light Company (DLC) submitted an application for license amendment for changes to Surveillance Requirement 4.6.2.2.e.3, Limiting Condition for Operation 3.6.1.4, and Figure 3.6-1 of the Beaver Valley Power Station, Unit 1 Appendix A Technica, Specifications (TSs).
The amendment would reduce the required river water minimum flow through the recirculation spray system (RSS) heat w hangers from 8000 gpm to 6000 gpm.
2.0 BACKGROUND
AND DISCUSSION The RSS draws water from the containment sump and delivers it to spray headers. The RSS water is cooled by heat exchangers using river water. The RSS heat exchangers.are located inside the containment building.
There are two trains of recirculation spray, and each train has two heat exchangers.
l During. quarterly inservice testing on October 3, 1990, a significant-flow reduction in RSS train "A" (IA-and IC heat exchangers) was observed. The "B" l.
train RSS heat exchangers were found with less significant flow degradation.
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'To verify the test results, Duquesne Light Company (DLC) performed -
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' an 18-month surveillance test on October 1?,1990.
This test provides a more l
representative alignment of plant equipment for. design basis accident (DBA)
. conditions. Based on the results obtained, the "1C" heat exchanger of the "A" itrain was declared inoperable and the. plant entered the Action Statement of TS
- 3.6.2.2.
Before-the expiration of the seven-day action statement, DLC requested a Temporary Waiver of Compliance (TWOC) to permit continued operation of the plant with less than 8000 gpm river water flow to the RSS heat exchangers.
The TWOC dated October 19, 1990, would be effective until the TS could be amended. DLC proposed a TS amendment by letter dated October 25, 1990. This Safety Evaluation documents the results of the staff review of that application.
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. 3.0 EVALUATION The surveillance requirements in TS 4.6.2.2.e.3 specifies a flow of at least 8000 gpm through each river water subsystem and its two associated RSS heat exchangers.
DLC evaluated the design basis requirements of the containment depressurization system for the reduced RSS heat exchanger river water flow and reanalyzed the containment depressurization capability following a LOCA using the LOCTIC computer code. The results showed that with river water flow to one train of RSS heat exchanger reduced to 6000 gpm the containment depressurization system continues to be capable of reducing the containment pressure to subatmospheric pressure within one hour and maintaining the pressure subatmospheric following a LOCA.
DLC has proposed to revise, temporarily, TS Limiting Condition for Operation 3.6.1.4, Figure 3.6-1, and Surveillance Requirement 4.6.2.2.e.3 to allow operation with a minimum flow of 6000 gpm per train until the eighth refueling outage.
Figure 3.6-1 would be revised to reflect the new containment depressurization analysis, include additional operating restrictions on the allowable river water temperature, and the allowable operating containment air partial pressure.
Reduction of river water flow rate through the RSS heat exchangers does not affect the containment peak pressure response in a LOCA analysis, but it may affect the capability to depressurize the containment following the accident.
DLC's analyses demonstrate that. the design basis requirements for the containment depressurization system would still be met with the deg" 1ed RSS heat exchanger river water cooling flow.
The staff has reviewed DLC safety analysis and finds that the methodology and computer code used in thn analysis are consistent with that discussed in the Final Safety Analysis Report (FSAR).
DLC also committed to monitor monthly the river water flow to the RSS heat exchanger trains exhibiting a flow less than 8000 gpm to ensure that the flow does not drop below the required 6000 gpm.
This increased surveillance will be applicable until the eighth refueling outage.
Based on DLC's safety analysis and the surveillance commitment, the staff has determined the reduced river water flow to the RSS heat exchangers would have a minor impact on the capability of the containment to depressurize to a subatmospheric condition within one hour following a LOCA.
Based on our review and evaluation of the consequences of river water flow to P.SS heat exchangers on containment depressurization capability, we find the effects to be minor; therefore, the staff finds that the proposed temporary l
license amendment is acceptable. However, reduced minimum RSS heat exchanger flow is acceptable only for the remainder of the current operating cycle, and minimum RSS heat exchanger water flow is to be restored to 8000 gpm prior to restart from the eighth refueling outage (about June 1991).
1 4.0 EMERGENCY CIRCUMSTANCES Surveillance Requirement 4.6.2.2.e.3 is performed once each 18 months to demonstrate that the flow through the RSS heat exchangers is adequate.
This i
surveillance test was last performed during the seventh refueling outage which ended December 25, 1989. That test showed that the flow through each RSS heat exchanger was 8400 gpm. Quarterly Inservice Testing (IST) program l
3 surveillance tests are conducted to demonstrate pump and valve operability in various systems. Quarterly IST tests performed on and after October 3,1990, revealed that the "A" Train flows were approaching the limit specified in TS 4.6.2.2.e.3.
Because of the flow degradation revealed by the IST tests, an 18 month i
surveillance test (which provides a more representative plant equipment alignment for DBA conditions than the IST test) was performed on October 12, 1990. The results of this test established the basis for the declaration of inoperability for the Train "A" of the RSS. This declaration placed the unit
.in a seven day action statement.
Subsequently, DLC attempted to identify the I
cause for the flow reduction, but these measures were largely inconclusive.
The RSS heat exchangers are located inside the containment building which is maintained at sub-atmospheric pressure. To disassemble and clean the heat exchangers would require a plant shutdown; therefore, prior to the expiration
.of the 7-day action statement, DLC requested and the NRC granted a TWOC on October 19, 1990, effective until an application for license amendment could be submitted, reviewed, and the amendment issued.
The' NRC staff does not believe that DLC has abused the emergency provisions of 10 CFR 50.91 in this instance. Accordingly, the Commission has determined that emergency circumstances existed warranting prompt approval, in that failure to act would have caused the plant to shutdown, and the situation could not have been-avoided. The amendment, as discussed in Section 5.0, does not involve a significant hazards consideration.
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5.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION
DETERMINATION The Commission.has made a final determination that the emendment involves.no-
.significant hazards consider.ation.- Under the Commission's regulations in 10 CFR 50.92(c), this means that:the operation of the facility in accordance with the proposed amendment would not (1) Involve a significant increase in the l
probability or consequences of an accident previously evaluated; or (2) Create-l the possibility _of a new or different kind of accident from any accident-previously evaluated; or'(3) Involve a significant reduction in a margin of-l safety.
The-Commission has evaluated the proposed. changes against the above standards; as required by 10 CFR 50.91(a)'and has concluded that:
'The change does not involve a significant increase in the A.
probabilit or consequences of an accident-previously evaluated (10 i
CFR 50.92(y)(1)) because the design basis requirements of the RSS c
heat exchangers will still be met even with the reduced river water flow, and the revised TS ensures that the assumed conditions in the revised containment depressurization analyses remain valid.
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4 B.
The' change does not create the possibility of a new or different kind of accident from any accident previously evaluated (10 CFR 50.92(c)(2)) because neither plant configuration nor the manner by which the facility is opereted is affected.
C.
The change does not involve a significant reduction in a margin of safety (10 CFR 50.92(c)(3)) because the same containment depressurization capability assumed in the original design will be retained.
-G.0 STATE CONSULTATION In accordance with the Commission's regulations in 10 CFR 50.91(b), the representative of the Commonwealth of Pennsylvania was consulted.
The representative had no coments with regard to this action.
7.0 ENVIRONMENTAt. CONSIDERATION-The amendment changes a requirement i ~h respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and a surveillance requirement.
We have determined that the amendment involves 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 staff has made a final determination'that this amendment
-involves no significant hazards consideration. Accordingly, the amendment meets 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 amendment.
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8.0 CONCLUSION
We have concluded, based on the considerations discussed above, Bat: (1) there is reasonable assurance that the health and safety of the.puulic 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 (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated: ' November 16, 1990 Principal Contributors:
J. S. Guo Albert W. De Agazio J