ML20072P917
| ML20072P917 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 11/20/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072P916 | List: |
| References | |
| NUDOCS 9011290251 | |
| Download: ML20072P917 (3) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGUtATION RELATED TO AMENDMENT No. 51 TO FACILITY OPERATING LICENSE NO. NPF 47 GULF STATES UTILITIES COMPANY RIVER BEND STATION. UNIT 1 DOCKET NO. 50-458 INTRODUCTION By letter dated October 12, 1990, Gulf States Utilities Company (GSU) (the licensee) requested an amendment to Facility Operating License No NPF-47 for the River Bend Station (RBS), Unit 1.
The proposed amendment would modify Technical Specification (TS) Table 3.8.4.1-1, " Primary Containment Penetration Conductor Overcurrent Protection Devices," Sections C.1 and C.4 to reflect the removal of load 1G36 C002, location INHS-MCC2E, cubicle 28 from Section C.1 and the addition of the load to location INHS-MCC20, cubicle 1E in Section C.4 The Reactor Water Cleanup (RWCU) system is designed to maintain reactor water quality by filtration and ion exchange.
For the past two operating cycles the RBS has been experiencing poor RWCU system performance.
As a result, the licensee identified a number of enhancements to improve RWCU system performance.
One area of improvement the licensee has identified deals with the precoat on the filter demineralizers.
The licensee determined a greater precoat flowrate would improve filter performance.
A larger RWCU precoat pump motor is needed to meet this increased flowrate.
The RWCU precoat pump is not safety-related, but is located in containment, therefore, the power supply containment penetration must be protected to ensure no loss of containment integrity occurs.
Because of the larger motor, a larger protection breaker could not be installed in panel INHS-MCC2E due to physical size and the electrical load restrictions.
Therefore, the proposed amendment requests the associated load in Section C.1 of Table 3.8.4.1-1 be removed and inserted in Section C.4.
The new circuit breaker (Gould type 80, FVNR size 3) listed in Section C.4 will provide primary containment penetration conductor overcurrent protection for the larger RWCU pump and necessitates the TS change.
EVALUATION As designed, the RDS RWCU filter demineralizers are wedgewire type septa with a precoat pump maximum flow capacity of 200 gallons per minute (gpm).
In the past, the wedgewire septa has exp rienced plugging with resin break-through.
This has resulted in poor RWCU filter domineralizer performance.
The wedgewire septh was replaced with porous metal setpa and a new pump impeller was installed which increased the flow rate to 260 gpm, but backwashes, due to high differential pressure, were experienced.
Upon further review, the licensee determined that three problSms were causing the poor filter performance.
The problems are currently beirg addressed in design
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modifications which include:
removing a check valve which was plugging; replacing the porous metal septa; designing a new vent system; and increasing the precoat flowrate from 260 gpm to 350-400 gpm by installing a larger pump mctor.
The new non-safety-related 50 horsepower, 3500 rotations per minute pump will i
require a larger protection breaker which could not be installed in the existing i
panel.
Therefore, the load is to be moved from the current load center to a new load center.
The new pump will be located in containment and will be powered by non safety-related power; however, the power cable must pass through a containment penetration.
Containment electrical penetrations are part of the primary containment pressure boundary.
RBS Safety Analysis Report (SAR)
Section 8.3.1.1.4.3 states that containment penetration assemblies are designed to withstand, without loss of mechanical integrity, the maximum fault current versus time condition which could occur because of a single random failure of the circuit overload protective devices.
Additionally, no single failure causes excessive current in penetration conductors which could degrade penetration seals and all protective devices automatically disconnect power to the penetration conductors when currents exceed the established protection limits.
Electrical penetrations containing 480 volt (V) power circuits are nominally rated to carry 180 percent of full load current cuntinuously with all other circuits in the same penetration operating at full load.
Overload protection of the 480 V motor control center power circuits is provided by a series-connected molded case circuit breaker and fuse.
Each is rated to open the circuit during overload conditions which provides redundant protection.
The circuit protection design for the larger RWCU pump motor conforms to these SAR requirements.
The design for the load to be added to Section C.4 is similar to the existing configurations for the circuits listed in the table.
Additionally, the design is in accordance with applicable TS bases and design criteria.
The NRC staff has reviewed the licensee's submittal and has found that the electrical penetration assembly for the larger RWCU precoat pump is designed to withstand, without the loss of mechanical integrity, the maximum available fault current versus time condition that could occur given a single random failure of the circuit overload protective device, as recommended by Regulatory Guide 1.63.
Based on its evaluat'$n, the staff also finds that the proposed change is in accordance witn "
ard Review Plan Section 8.3.1.
Therefore, the proposed change is acceptab.
ENVIRONMENTAL CONSIDERATION The amendment involves a change in a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes in surveillance r luirements.
The staff has deter-mined that the amendment involves no significant incraase 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 ocrupational I
radiation exposures.
The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration and there has
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. s been no public comment on such finding.
Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or *tvironmental assessment need be prepared in connection with the issuance of the amendment.
CONCLUSION The staff 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, and (2) such activities will be conducted in compliance with the Commission'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.
The staff therefore concludes that the proposed changes are acceptable.
Dated:
November 20, 1990 Principal Contributor:
Claudia M. Aobate, PDIV-2 1