ML19344E721
| ML19344E721 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 08/14/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19344E720 | List: |
| References | |
| NUDOCS 8009110033 | |
| Download: ML19344E721 (3) | |
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WASHINGTON, D. C. 20565 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. p; TO FACILITY OPERATING LICENSE NO. NPF-2 ALABAMA POWER COMPANY JOSEPH M. FARLEY NUCLEAR PLANT, UNIT N0. 1 DOCKET N0. 50-348 1.
Low-Low Steam Generator Water Level Reactor Trio Setooint INTRODUCTION By letter dated August 30, 1980, supplemented by letter dated March 31, 31, 1980 the licensee (Alabama Power Conpany) proposed changes to the Technical Specifications for the Farley Nuclear Plant, Unit No.1.
The changes would increase the low-low steam generator water level reactor trip setpoint from 15% to 17% of the narrow range instrument scale.
The revised value of 17% includes an allowance of 5% for channel accuracy, 10% for post-accident environmental effects on the differential pressure transmitter, and 2% for reference leg heatup compensation.
DISCUSSION High energy line breaks inside containment can result in heatup of the steam generator water level instrument's reference _ leg.
Increased reference leg water column temperature will result in a decrease of the water column density with a consequent apparent increase in the indicated steam generator water level (i.e., indicated level exceeding actual level).
This potential level bias could result in delayed protection signals (reactor trip and auxiliary feedwater initiation) that are based on low-low steam generator water level.
For the case of a feedline rupture, this adverse environment could be present and could delay the primary signal arising from declining steam generator water level (low-low steam generator water level).
High pressurizer pressure, over-temperature delta T, high containment pressure and safety injection are backup signals to steam generator water level with an adverse containment envi ronment.
For other high energy line' breaks that could introduce a similar positive bias to the steam generator water level measurement, steam generator level does not provide the primary trip function and the potential bias would not interfere with needed protective system actuation.
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& EVALUATION Westinghouse (NSSS vendor for the Farley Plant) has advised that the potential temperature-induced bias described above can be compensated for by raising the steam generator low-low water level setpoint.
Westinghouse has recommended a change in the allowable water level setpoint sufficient to accommodate the bias that could result from the highest containment temperatures possible prior to the occurrence of a containment high pressure trip.
Based on the spectrum of steam line breaks for the Farley Nuclear Plant, this temperature is 238'F.
To correct the potential error, the licensee has added two inches of insulation to the reference leg to minimize the effect of adverse contain-ment temperatures on the reference leg. The insulating material used is " Temp-Mat," a needled fiberglass insulation with no oroanic binder.
The insulation is wrapped to prevent damage.from condensation during an accident, protected from high energy line break jet impingement forces by physical location, and is qualified for use in a post-accident containment envi ronment.
Analyses, shown in the licensees letter of March 31, 1980, have shown that with a boundary condition of 245*F, that after 5 minutes (the period of interest where the reactor trip function is needed) the total error resulting from the reference leg heatup is less than 2%.
Thus, the 2% increase in the low-low water level setpoint will provide a reactor trip and auxiliary feedwater initiation following a feedline rupture.
The proposed change in setpoint will ensure that the trip setpoint maintains conservatism and compensates for the potential temper-ature induced error.
CONCLUSION Based on our review of the licensee's submittals, the proposed changes to Table 2.2-1 and Table 3.3-4 of the Technical Specifications are r-acceptable.
2.
Correction of Number of 600 Volt Load Centers _-
INTRODUCTION By letter dated June 2, 1980, the licensee proposed a correction to Technical Specification 3.8.2.2.
Another change relating to definition of the term " operable" contained in this same letter will be completed by separate amendment.
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. EVALUATION Technical Specification 3.8.2.2 lists the train-oriented AC electrical buses which shall be operable during Modes 5 and 6.
The list contains five 600 volt load centers.
Farley Plant has only four 600 volt load centers. Thus, the licensee has proposed a pro-forma change.
We concur that this was an obvious typographical error which is now being corrected.
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 standpoint of environmental irpact and, pursuant to 10 CFR 51.5(d)(4), that an environmental impact statement or negative declaration ar.d environ-nental impact appraisal need not be prepared in connection with the issuance of this amendment.
CONCLUSION We have concluded, based on the considerations discussed above, that:
(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 that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities 5:111 be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date: August 14, 1980
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