ML17311A658
| ML17311A658 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 02/09/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17311A657 | List: |
| References | |
| NUDOCS 9502160386 | |
| Download: ML17311A658 (6) | |
Text
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t UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTO."l,'O.C, 20555 0%1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 89 0
CILITY OPERATING LICENSE NO.
NP -41 AMENDMENT NO.
76 TO FACILITY OPERATING'ICENSE NO, NPF-51 I
ENNNE T
A IEITT PEIIATIN El E~NN N I-RIZONA PUBL C
S RVICE COMPANY E
AL.
PALO VERD NUCLEAR GENERATING STATION UNIT NOS. I 2
AND 3 DOCKET NOS.
STN 50-528 STN 50-529 AND STN 50-530
- 1. 0 INTRODUCTION By letter dated October 31,
- 1994, as supplemented by letter dated December 28, 1994, the Arizona Public Service Company (APS or the licensee) submitted a
request for changes to the Technical Specifications (TS) for the Palo Verde Nuclear Generating
- Station, Units 1, 2, and 3 (Appendix A to Facility Operating License Nos. -NPF-41, NPF-51, and NPF-74, respectively).
The Arizona Public Service Company submitted this request on behalf of itself, the Salt River Project Agricultural Improvement and Power District, Southern California Edison
- Company, El Paso Electric Company, Public Service Company of New
- Mexico, Los Angeles Department of Water and
- Power, and Southern California Public Power Authority.
The proposed amendment would change the refueling machine overload cutoff limit from less than or equal to 1556 pounds to less than or,equal to 1600 pounds.
The change was requested because design and fabrication improvements have increased'he weight of the fuel assembly.
2.0 BACKGROUND
The purpose of refueling machine overload cutoff limit in TS 3/4.9.6, "Refueling Machine," is to ensure that the core internals and the pressure vessel are protected from excessive lifting force in the event that they are inadvertently engaged during lifting operations.
Currently, TS 3/4.9.6 specifies the refueling machine overload cutoff limit to be less than or equal to 1556 pounds.
The licensee has proposed to increase this limit to less than or equal to 1600 pounds.
The licensee stated that the increase in the cutoff limit is necessary because modifications to the ABB-CE fuel assembly have increased its weight.
The modified fuel pellet has a
slightly larger outside diameter, a reduced dish volume, and a reduced chamfer height, providing more energy per unit volume and reducing the propensity for end capping and chipping.
The previous Inconel Grid Assembly is replaced with a redesigned Inconel Spacer Grid Assembly called Guardian'".
The Guardian'",
with its design features, improves the Inconel spacer grid assembly's ability 9502ib038b 950209 t
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to entrap debris.
The spacer grid assemblies were also redesigned to improve the coolant flow between the fuel rods located along the periphery of the fuel bundle.
Laser welding also produces a smaller and more uniform nugget.
This small weld nugget reduces the grid's pressure drop coefficients, thereby producing greater thermal margin.
The licensee estimated that the modifications have increased the weight of the fuel assembly by 25 pounds.
The licensee stated that these modifications were evaluated in accordance with the provisions of 10 CFR 50.59 and found to be acceptable.
- 3. 0 EVALUATION The fuel overload cutoff limit for the refueling machine hoist is intended to protect the core internals and the pressure vessel from possible damage in the event the fuel assembly becomes mechanically bound as it is withdrawn from the reactor vessel.
The licensee stated that the overload cutoff limit is determined by adding the wet weight of the refueling machine hoist, the refueling machine grapple, the heaviest fuel assembly, and an additional 90 pounds.
The figure of 90 pounds is based on two considerations:
(1) it is large enough to account for friction loads during fuel assembly withdrawal and (2) it is small enough to ensure that, while a minimum weight fuel assembly is being lifted, the loads imposed on a mechanically bound fuel assembly are below the design limit specified by the fuel manufacturer.
The maximum value for the overload cutoff limit was specified by the fuel manufacturer to be.1602 pounds.
The proposed 1600 pound overload cutoff limit is bounded by the fuel manufacturer's specified value.
Although the difference between, the proposed overload cutoff limit and the maximum manufacturer-specified value is 2 pounds (vs.
46 pounds difference between the current overload cutoff limit and the maximum manufacturer-specified value),
the new cutoff limit is more conservative than it appears, since the manufacturer's calculation of the maximum weight is based on fuel assemblies that have a
14 x 14 pin arrangement whereas Palo Verde fuel assemblies have a
16 x 16 pin arrangement with more welds.
The additional weld geometry was reviewed by the licensee and estimated to increase the maximum manufacturer's value for the overload limit by 20 pounds (i.e.,
up to 1622 pounds).
To minimize the use of the overload cutoff limit, the refueling machine normal operating procedures caution the operator to stop the hoist if the indicated load varies by more than 50 pounds from the weight being handled.
The 50-pound overload condition is more restrictive than the overload'cutoff limit.
In addition,. the fuel assembly grids have been designed with lead-in features to minimize the potential for mechanical binding.
The staff reviewed the proposed increase in the refueling machine overload cutoff limit to less than or equal to 1600 pounds and concluded that the revised overload cutoff limit continues to be maintained below the manufacturer's specified value.
Additionally, plant specific weld geometry and procedural controls provide additional margin to the overload cutoff condition.
Therefore, the proposed TS change is acceptable.
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4.0 STATE CONSULTATIO In accordance with the Commission's regulations, the Arizona State official was notified of the proposed issuance of the amendments.
The State official had no comments.
- 5. 0 ENVIRONMENTAL CONSIDERATION The amendments change 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 change surveillance requirements.
The NRC staff has determined that the amendments involve 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
proposed finding that the amendments involve no significant hazards considera-tion, and there has been no public comment on such finding (60 FR 2160).
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
- 6. 0 COHCLUS ION 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:
L. Tran, NRR Date:
February 9,
1995
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