ML19275A829
| ML19275A829 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 09/27/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19275A825 | List: |
| References | |
| NUDOCS 7910190158 | |
| Download: ML19275A829 (2) | |
Text
.
gn %
y,
,g UNITED STATES g
NUCLEAR REGULATORY COMMISSION y
E WASHINGTON D. C, CS55 o
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0.45 TO FACILITY OPERATING LICENSE NO. OPR-36 MAINE YANKEE ATOMIC POWER COMPANY MAINE YANKEE ATOMIC POWER STATION DOCKET NO. 50-309
_ INTRODUCTION In response to our request of July 18, 1977, the Maine Yankee Atomic Power Company (the licensee) proposed, on September 16, 1977, additional surveillance requirements with respect to emergency core cooling system (ECCS) flow distribution.
We have evaluated the proposed change.
EVALUATION The High and Low Pressure Safety Injection System (HPSI and LPSI) designs of many Pressurized Water Reactors (PWR) utilize a common low pressure and a comon high pressure header to feed the several cold (and in some cases hot) leg injection points.
Maintenance of proper flow resistance and pressure drop in the piping system to each injection point is necessary to:
(1) prevent total pump flow from exceeding runout conditions when the system is in its minimum resistance configuration; (2) provide a proper flow split between injection points in accordance with the assumptions used in the ECCS-LOCA (Loss of Coolant Accident) analyses, and (3) provide an acceptable level of total ECCS flow to all injection points equal to or above that assumed in the ECCS-LOCA analyses. On many plants, there are motor operated valve (s) in the lines to each injection point that have stops which are set during pre-operational flow testing of the plant to insure that these flow requirements are satisfied.
On other plants, electrical or mechanical stops on the Safety Injection System's isolation valve (s) are used for this purpose. Maine Yankee utilizes motor operated valves to satisfy these ECCS flow requirements for the HPSI system.
While pre-operational HPSI flow testing is utilized to assure that the valves used to throttle flow have been properly set, the NRC staff has concluded that periodic surveillance requirements are needed to assure that these settings are maintained throughout the life of the plant.
Consequently, we requested ull PWR licensees to propose changes to their Technical Specifications, as appropriate, to incorporate periodic surveillance requirements for these valves.
Sample surveillance requirementsr, developed by the NRC staff, were pro'
' to licensees for guidance in developing proposed changes.
The sample requirements include periodic verification of throttle valve position stop settings, and verification of proper ECCS flow rates whenever system modi-fications are made that could alter flow characteristics.
The request for proposed Technical Specification changes was sent to the licensee on July 18, 1977.
The licensee responded to our request with respect to Maine Yankee by submittal dated September 16, 1977.
This submittal contained proposed chan s to the 1180 254 1
7 7910100
4 Technical Specifications that are in essential agreement with the NRC staff's requirements.
Based on our review, we have concluded that thc licensee's proposed increased surveillance requirements would provide sufficient additional assurance that proper valve settings for ECCS flows and flow distri-butions will be maintained throughout plant life; and thus, the proposed changes are acceptable.
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 impact, and pursuant to 10 CFR 651.5(d)(4), that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance cf the 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 healtE 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 the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated:
September 27, 1979 l180 255