ML20010F403
| ML20010F403 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 08/27/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20010F399 | List: |
| References | |
| NUDOCS 8109100141 | |
| Download: ML20010F403 (4) | |
Text
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SAFETY EVALUATION'BY THE OFFICE OF NUCLEAR REACTOR REGUl'ATION RELATED TO AMENDMENT NO. 7 TO FACILITY OPERATING LICENSE N0. NFP-8 ALABAMA POWER COMPANY JOSEPH'M. FARLEY NUCLEAR PLANT, UNIT N0. 2 DOCKET NO. 50-364 Introduction By letter dated August 24, 1981, supplemented by letter dated August 25, 1981 Alabama Power Company ( APCo) proposed a one-time Technical SpecUi-cation change. The change involved the failum of one of the four contain-ment cooling fans at Farley Unit 2.
The fan failure placed the plant into a Technical Specification Action Statement requiring plant shutdown in seven days unless the fan could be repaired. APCo stated that mpairs could be accomplished only at cold shutdown because of limited personnel stay times in containment.
Since the next cold shutdown was scheduled about October 5,1981, APCo modified the proposal of August 24 to be a one-time extension of the seven day allowable outage to 47 days. Their evaluation showed that the extended time would also allow them to be better prepared to perform the fan repairs and other plant repairs after the summer peak load period. Subsequent analysis indicated that the original plent design of fan coolers may have been overconservative.
Therefore, by letter dated August 27, 1981, APCo withdrew its proposal for a one-time extension to 47 days.
Instead APCo proposed a redefinition of the number of containment cooler fans required. This resulted in a new Technical Specification proposal evaluated herein. The proposal would define a fan group as one fan instead of two fans. This would eliminate the need to shutdown the plant in se/cn dcys if any one of four fans became inoperable.
Discussion The containment heat removal system for the Farley Nuclear Plant, Unit 2, corisists of four containment cooling fans (fan coolers) and two containment pray systems. The components are divided between two emergency trains, each possessing two fan cooler units and one containment spray system and powered from a separate diesel generator in the event of loss of offsite power.
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During normal plant operation three fan coolers are used to control contain-ment heat loads.
During normal operation each fan cooler is run at high speed and has one-third heat removal capability. Should an accident signal occur all four fan coolers receive a start signal and automatically go to low speed.
Each fan cooler was originally designed for a 25% containment heat removal capability under accident conditions.
Each of the containment spray systems was originally designed for a 50% containment heat removal capability under accident conditions. Therefore each of the separate emergency trains.of fans and pumps was designed for 100% containment heat removal capability with all components operable.
At 6:00 a.m. on August 21, 1981 while perfonning operability checks, the motor for the D Containnent Cooling Fan was found to be inoperable. The action statement of Technical Specification 3.6.2.3.a states that the fan cooler unit must be repaired within seven days or Unit 2 must be placed in Hot Shutdown.
Although APCo estimates that the fan cooler repairs would g
require only three to four days effort under optimum conditions, the radia-tion levels ar.d the elevated temperature inside containment (approximately 110-112 F) would necessitate shutting down the plant to cold shutdown before maintenance workers could enter containment.
Due to large summer electricity needs and the critically low water levels at the hydroelectric storage reservoirs, the licensee has asked to defer the fan cooler repairs.
The next scheduled extended outage for Farley Unit 2 is not later than the week of October 5,1981.
The licensee has proposed to defer the fan cooler repairs to this time. By deferring the fan cooler maintenance to the next scheduled plant shutdown, the licensee can both avoid shutting down the Farley Unit 2 facility during this critical time of power need and better utilize the shutdown period since more time will be available for planning and prepar-ation for maintenance and design improvements.
By letters dated August 24 and 25,1961, APCo proposed a one-time only Technical Specification change to extend the seven ' day action statement of Specification 3.6.2.3.a by 40 days (47 days total). This extension would allow the licensee to repair the fan cooler motor during the scheduled October outage.
Subsequently by letter dated August 27, 1981, APCo showed by analysis (included in the Evaluation below) that the Limiting Condition for Operation (LCO) requiring that all four containment fan coolers be operable in Modes 1, 2 and 3 was overly conservative.
Revised accident analysis showed that the limiting Loss of Coolant Accident (LOCA) and Main Steam Line Break (MSLB) could be adequately handled assuming the loss of a diesel generator concurrent with the loss of a fan cooler from the unaffected train.
Due to the revised analy-sis, the licensee proposed that the LC0 be changed such that only one of two fan coolers in each group be required to be operable.
This new proposal negates the need for the temporary 40 day extension to action statement 3.6.2.3.a.
Evaluation Analysis Report (FSAR) presented in Section 6.2.1 of the Farley Findl -Safety The accident analysis only requires that two of the four fan coolers and one of the two containment spray pumps be operable.
Considering loss of offsite power and the single failure of an emergency diesel generator, the containment heat removal system would still provide for 100% heat removal capability during the post-accident mode.
The licensee's proposal, however, can lead to a scenario more severe than that analyze'd in the FSAR. The proposal leaves only one fan cooler and one spray pump in each operating train.
If a LOCA was postulated concurrent with loss of offsite power and the single failure of a diesel generatcr, the facility would only have 75% of the design post-accident containment heat removal capability.
The licensee has submitted reanalysis of the limiting pressure and temperature calculations for containment design assuming only one fan cooler and one containment spray pump uperable. The licensee has shown that design of the original containment heat removal capacity was overly conservative.
Analysis shows that by using only 75% of the design value, the containment heat removal needs were adequately supplied.
The limiting pressure calculation (due to LOCA) increased by 2.1 psi to 48.4 psig. Sufficient margin still exists below the containment design pressure of 54.6 psig. The long term containment pressure profile remains virtually unchanged. The limiting temperature calculation (due to a MSLB) mmains the same at 381 F.
This is because the containment spray system dominates the temperature transient in containment.
The licensee assumed a 5% reduction in the containment spray flow rate which adds further conservatism to the calculations.
Conclusion We have reviewed the licensee's proposed amended Technical Specification changes and the supporting analysis. We conclude that the proposed change does not involve an unreviewed safety question and will not affect the safe operation of the facility. Therefore, we find the proposed Technical Specification change acceptable.
Environmental Consideration We have cetermined that the amendnent does not authorize a change in effluent types or total amounts nor an increase in power le vel and will not result in any significant environmental impact. Having nade this determination, we have further cpncluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 51.5(d)(4), that an
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environmental impact statement or negative declaration and environ-mental inpact appraisal need not be prepared in connection with the issuance of this amendment.
Conclusion We have concluded, based on the considerations discussed above, thati (1) because the amendment does not involve a significant increase 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 consideration, (2) there is reasonable assurance tnat the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Conmission's regulations and the issuance of this amendment wfil not be inimical to tne ccanon defense and security or to the health and safety of the public.
Date:
August 27, 1981 1
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