ML20086F553
| ML20086F553 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 07/06/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20086F547 | List: |
| References | |
| NUDOCS 9507130177 | |
| Download: ML20086F553 (3) | |
Text
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Oro 25 UNITED STATES ye 4
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- NUCLEAR REGULATORY COMMISSION
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' WASHINGTON, D.C. 20065 4001 l
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.100 TO FACILITY OPERATING LICENSE NO. NPF-30 1
UNION ELECTRIC COMPANY CALLAWAY PLANT. UNIT I D0C.KET NO. 50-483 l.0 INTRODUCTION By letter dated July 16, 1993, Union Electric Company (UE), requested an amendment to Operating License NPF-30, which would change the Technical Specifications (TS) for the Callaway Plant, Unit 1.
The proposed amendment would revise TS 3/4.8.1.1, "A. C. Sources Operating," and 3/4.8.1.2, "A.
C.
l Sources Shutdown," to change the minimum required storage volume of the Emergency Fuel Oil (EF0) storage tank from 85,300 gallons to 80,400_ gallons and the EF0 day tank from 390 gallons to 510 gallons.
2.0 BACKGROUND
4 During the performance of a self-initiated electrical distribution system functional assessment (EDSFA), UE identified inconsistencies in the calculations for the capacity of the emergency fuel oil (EFO) storage and day tanks.
It was determined that the calculation was based on a specific gravity of 28 degrees American Petroleum Institute (API). TS allow a fuel oil specific gravity range between 27 and 39 degrees API. Using a 39-degree API i
specific gravity in lieu of a 28-degree API specific gravity would provide a more conservative assumption for calculating the required tank volumes.
The higher specific gravity corresponds to a lower density (lighter weight fuel) and larger minimum tank volume, applicable to both the storage and day tanks.
UE also identified an inaccurate assumption used to calculate net positive suction head available (NPSHA) for the transfer pumps in the EF0 storage tanks.
These inconsistencies were confirmed ouring an NRC performed electrical distribution system functional inspection (EDSFI)(50-483/93009).
The changes are considered TS enhancements as identified by NUREG-1431, " Westinghouse Technical Specification Improvements."
2.0 EVALUATION Callaway has two emergency diesel generators (DG).
Fuel oil is supplied to each DG by an EF0 day tank, located in the DG room.
Each day tank is sized to contain sufficient fuel to ensure continuous DG operation for one-hour, under i
full load conditions. An adequate fuel oil supply is ensured by the level setting on the day tank which provides for one-hour fuel oil supply plus an additional 10% margin.
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i 2-i The EF0 day tanks are gravity fed and are wall-mounted at an elevation to ensure adequate net positive suction head for the engine-driven fuel oil pumps on the DGs.
The day tanks ensure a minimum of one hour's supply of fuel for the DGs running at their continuous rating, plus a 10 percent margin.
In calculating the amount of fuel oil required in the day tanks, a specific i
gravity of 28 degrees API was assumed.
However, TS 4.8.1.1.2d.(1)(a) allows fuel oil with a specific gravity of greater than or equal to 27 degrees API but less than or equal to 39 degrees API to be used. With the less dense fuel (39 degrees API), more fuel is required in the day tanks to provide the one i
hour operation of the DG at rated load, plus an additional 10 percent.
Results of the revised calculations indicate that a minimum fuel oil supply of 510 gallons (including a 10 percent margin in accordance with the guidance described in ANSI N195-1976) is required to be stored in each day tank.
The EF0 storage tanks are underground tanks sized to provide diesel generator (DG) operation at continuous rating for seven days plus an additional volume used for monthly testing. When the day tank reaches the low level setpoint, oil from the underground storage tank is pumped into the day tank by a transfer pump located in the storage tank.
UE determined that original calculations did not appropriately determine the
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NPSHA for the transfer pump.
The NPSHA calculation did not account for the
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absolute pressure on the fuel oil due to atmospheric pressure, which resulted in a higher static elevation of fuel oil than needed for proper pump operation. This oversight resulted in a larger unusable volume of fuel oil which required an overly conservative minimum storage tank volume.
The licensee utilized the corrected parameters of the highest allowable fuel oil viscosity and a conservative atmospheric pressure for determining the absolute pressure. These conservatisms provided the minimum static height of fuel oil in the storage tank which would ensure adequate suction to the pump for proper operation under worst case conditions. The change (increase) in EF0 storage tank volume that corresponds to the corrected transfer pump NPSHA calculation is greater than the change (decrease) associated with the more conservative assumption for the fuel oil specific gravity (28 degrees API).
Consequently, 80,400 gallons of fuel oil supply is determined to be sufficient for one EDG 7-day operation following a design basis accident.
The revised calculations require changes to the minimum storage volume of the i
EF0 storage and day tanks as referenced in the current TS 3/4.8.1.1 and 3/4.8.1.2.
The proposed changes will decrease the EF0 storage tank volume to 80,400 gallons from 85,300 gallons and increase the EF0 day tank volume to 510 i
gallons from 390 gallons.
1 This change does not involve any modification of the equipment and does not affect the long-term operation of the emergency diesel generators.
On the basis of the above evaluation and the results of the onsite EDSFI, the staff concludes that Callaway will have adequate and reliable fuel oil inventory in the day tanks for 1-hour DG operation and in the storage tanks for 7 days of i
continuous DG operation following a design basis accident.
Therefore, the staff has determined that the proposed changes are acceptable.
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3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Missouri State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATI03 The amendment changes 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 surveillance requirements. The 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 l
and that there is no significant increase in individual or cumulative i
occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding (59 FR 17607). Accordingly, this amendment meets 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 this amendment.
5.0 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, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
L. R. Wharton i
Date:
July 6, 1995 I
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