ML20114F814
| ML20114F814 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 10/02/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20114F812 | List: |
| References | |
| NUDOCS 9210130322 | |
| Download: ML20114F814 (2) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.136 TO FACILITY OPERATING LICENSE NO. NPF-6
[NTERGY OPERATIONS. INC..
ARKANSAS NUCLEAR ONE. UNIT NO.__2 DOCKET NO. 50-368
1.0 INTRODUCTION
By letter dated August 4, 1992, Entergy Operations, Inc. (the licensee),
submitted a request for changes to the Arkansas Nuclear One, Unit No. 2 (ANO-2) Technical Specifications (TSs).
The requested changes would revise Technical Specification (TS) 4.7.1.2,a.1 to decrease the value of the secondary steam supply pressure specified for surveillance of the turbine-driven emergency feedwater (EFW) pump from greater than 865 psig to greater than 800 psia (785 psig).
In addition " secondary steam supply pressure" is changed to " steam generator pressure."
2.0 EVAL'JATION The most probable cause of degradation of the ANO-2 Steam Generator tubes is intergranular stress corrosion cracking (IGSCC).
To mitigate the consequences of IGSCC, the licensee is considering reduction of the primary-side temperatures of 607'F for the hot leg and 553*F for the cold leg to approximately 599'F and 545'F, respectively. The new primary-side temperatures will reduce the secondary steam supply pressure from an approximate value of 915 psia to 850 psia.
Currently, TS 4.7.1.2.a.1 requires surveillance of the turbine-driven emergency-feedwater (EFW) pump every 31 days to verify that the pump delivers a flow of 2485 gpm to the steam generator (SG) at a discharge pressure of 21200 psig when secondary steam supply pressure is >865 psig. With the new reduced primary temperatures, AN0-2 would be required by the surveillance to raise the hot-leg temperature or reduce the plant load until secondary steam supply pressure exceeded 865 pstg (880 psia).
Raising the hot-leg timperature or reducing the plant load on a monthly basis could increase the possibility.
of a reactor transient due to primary temperature effects, reactor power changes affecting xenon, tilt and axial power shape, and secondary-system-induu d perturbations. Changing TS 4.7.1.2.a.1 to require a steam supply pressure of >800 psia will allow surveillance testing of the EFW pump under stable conditions at the new reduced primary temperatures.
9210130322 921002 DR ADOCK 05000368 PDR
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The turbine-driven EFW pump curves and the expected performance curve for the turbine driver show that a steam inlet pressure of 250 psig available to the -
trip and throttle valve of the turbine driver is sufficient to provide a 485 gpm flow rate, at a discharge pressure of 1277 psig. The secondary steam supply pressure of approximately 850 psia (835 psig) will greatly exceed the needed 250 psig.
Based on its review, the staff concludes that decreasing'the value of:the secondary steam Fupply pressure required by TS 4.7.1.2.a.1 from
>865 psig to >800 psia (785 psigt is acceptable. Additionally, the substitution of " steam generator pressure" (with units in psia) for " secondary steam supply pressure" (with units in psig) clarifies the specification, reflects the instrumentation used to measure the secondary steam supply pressure for this surveillance, and is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Arkansas State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONS 10ERATl0N The amendment changes a requirement with respect to installation or use of-a facility component located within the restricted area as defined in 10 CFR Part 20 and changes in surveillance requirements.
The NRC staff has 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 Commission has previously issued a pro-posed finding that the amendment involves no significant hazards consideration, and there has been no public t.omment on such finding (57 FR 40210 and 41793). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR SI.22(b) no environmental impact statement or envirc = ental assessment need be prepared in connection with the issuance of th'e amendment.
5.0 CONCLUSION
The Commission has 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, (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.
Principal Contributor:
R. Twigg, PDIV-1 Date: October 2, 1992
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