ML20078G282
| ML20078G282 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/17/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20078G271 | List: |
| References | |
| NUDOCS 9411150576 | |
| Download: ML20078G282 (5) | |
Text
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UNITED STATES '
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NUCLEAR REGULATORY COMMISSION t
WASHINGTON, D.C. 20606-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.97 TO FACILITY OPERATING LICENSE NO. NPF-49 NORTHEAST NUCLEAR ENERGY COMPANY.'ET AL.
MILLSTONE NUCLEAR POWER STATION. UNIT NO. 3 DOCKET NO. 50-423
1.0 INTRODUCTION
By letter dated September 30, 1993, as supplemented July 8,1994, the Northeast. Nuclear Energy Company (the licensee), submitted a request for changes to the Millstone Nuclear Power Station, Unit No. 3 Technical Specifications (TS). The requested changes would revise the TS by increasing the minimum volume.of fuel oil required to be stored in the emergency diesel generator (EDG) day tank from 205 gallons to 278 gallons, and would clarify the bases for the EDG fuel oil storage tank and day tank minimum volume requirements. The July 8,1994, letter provided clarifying information that did not change the initial proposed no significant hazards consideration determination.
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2.0 BACKGROUND
There are two EDGs and their associated fuel' oil storage and transfer systems for Millstone 3.
The fuel oil storage and transfer systems for each EDG consist of:
a 550-gallon day tank which was designed to provide sufficient fuel oil to power the EDG at continuous rated load for approximately 1-1/2
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hours; a 35,000 gallon Fuel oil storage tank-which was designed to store sufficient fuel oil to power the EDG on the basis of the continuous rated load l
for 3-1/2 days; two ac motor-driven transfer pumps (one pump powered from the i
associated EDG and the other capable of being powered from either EDG); and associated piping, valves, instrumentation, and controls. The fuel oil storage and transfer systems for the EDGs at Millstone 3, were designed in j
such a way so that fuel oil can be transferred-from'either storage tank to either EDG or both EDGs to permit the operation of one EDG at the continuous rated load for a minimum of 7 days without replenishment of fuel. This is accomplished by a cross-tie with two normally locked-closed valves between the two EDG fuel oil supply headers and by having one fuel oil transfer pump on each storage tank capable of being powered from either the division A or division B electrical.
j 9411150576 941017 PDR ADOCK 050004 3 P
- During a review of EDG loading calculations as part of a self-assessment in the form of an in-house electrical distribution system functional inspection at Millstone 3, the licensee identified discrepancies in the EDG fuel oil storage capacity. Subsequently, a re-evaluation (using more conservative input parameters e.g. increased post-accident electrical loads, worst case instrument errors, effect of variations in the fuel oil specific gravity, considerations of vortex formation in the day tank, etc.) was performed to verify the capacity of the EDG fuel oil storage and day tanks.
Results of the re-evaluation indicated that the fuel oil storage tank capacity would provide a calculated run time of slightly greater than 3 days. The two tank storage capacity to support 7 day operation of a single EDG was reduced to slightly greater than 6 days. The day tank storage capacity was reduced from 1-1/2 hours to 3/4 of an hour.
Accordingly, by letter dated September 30, 1993, the licensee requested an amendment to Operating License NPF-49. The amendment, which proposed changes to TS Sections 3.8.1.1.b.1 and 3.8.1.2.b.1, and TS Bases Section 3/4.8, will increase the volume of fuel oil required to be stored in the EDG day tank, and clarify the bases for the EDG fuel oil storage tank and day tank minimum fuel oil inventory requirements.
3.0 EVALUATION
3.1 Proposed TS Changes
The licensee proposed to revise TS Sections 3.8.1.1.b.1 and 3.8.1.2.b.1 by increasing the minimum volume of fuel oil required to be stored in the 550-gallon day tank of each EDG from 205 gallons to 278 gallons.
Increasing the minimum fuel oil volume required to be stored in an EDG tank will result in extending the EDG run-time from 23 minutes to 27 minutes at the 2,000 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> rating of 5335 kW without makeup to the day tank.
This proposed TS does not conform with the guidance described in ANSI N195-1976, " Fuel Oil System for Standby Diesel Generators," which is endorsed by the Regulatory Guide 1.137 and the Standard Review Plan. ANSI N195-1976, in i
part, states that:
"Each diesel shall be equipped with day or integral tank i
or tanks whose capacity is sufficient to maintain at least 60 minutes of operation at the level where oil is automatically added to the day or integral tank or tanks. This capacity shall be based on the fuel consumption at a load of 100% of the continuous rating of the diesel plus a minimum margin of 10%."
U.; ring a meeting held on June 22, 1994, with the NRC staff, the licensee indicated that the day tank is normally filled to the capacity which would be sufficient to maintain approximately 60 minutes of EDG operation at the 2,000 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> rating (which is approximately 10% higher than the continuous rating).
However, during or after an EDG test run per the surveillance requirement, the fuel oil inventory in the day tank may decrease to a level which is below the 1-hour EDG run time capacity and above the proposed TS limit.
In order to
r ensure that the day tank is normally filled to the capacity.which would be sufficient to maintain approximately 60 minutes of EDG operation at the 2,000-i hour rating, the licensee agreed to revise operating / surveillance procedures to require that the EDG day tank will be refilled after completing.each EDG -
run.
i In the response, dated July 8, 1994, to the staff's request for additional i
information (RAI), dated April 7,1994, the licensee re-stated its commitment l
regarding the refilling of the day tank after each EDG operation.
Based on its review and the above cited licensee's commitment, the staff concludes that the fuel oil inventory in each of the EDG day tanks at Millstone 3, meets the intent of the guidance described in ANSI N195-1976.
l Therefore, the staff finds the above proposed TS changes acceptable.
3.2 Proposed Changes to TS Bases The licensee proposed to add the following two paragraphs to TS Bases Section 3/4.8:
a.
Technical Specifications 3.8.1.1.b.1 and 3.8.1.2.b.1. require a minimum volume of 278 gallons be contained in each of the diesel generator day tanks. This capacity ensures that minimum usable volume of 189 gallons is available to permit operation of each of the diesel generators for approximately 27 minutes with the diesel generators loaded to 2,000 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> rating of 5335 kW. The shutoff level for the (two) fuel oil 1
transfer pumps is 493 gallons (413 gallons usable volume)
-which corresponds to approximately 60 minutes of engine operation at the 2,000 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> rating. The first pump has a make-up setpoint of 372 gallons (284 gallons usable volume) which corresponds to approximately 42 minutes of operation at 2,000 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> rating. The 278 gallon day tank low level value corresponds to the auto make-up setpoint of the second pump and is therefore the lowest value of fuel oil.with auto make-up capability. Loss of the two redundant pumps would cause day tank level to drop below the minimum value.
The above proposed paragraph to be added to TS Bases Section 3/4.8 will clarify the intent of TS Sections 3.8.1.1.b.1 and 3.8.1.2.b.1 to ensure the availability of minimum usable volume of fuel oil to be stored in each of the l
EDG day tanks for the operation of each of the EDGs for a specific time period.
i Based on its review and evaluation of the proposed TS changes described in Section 3.1, the staff finds the above proposed paragraph to be added to TS Bases Section 3/4.8 acceptable.
I i b.
Technical Specifications 3.8.1.1.b.2 and 3.8.1.2.b.2 require a minimum volume of 32,760 gallons be contained in each of the diesel generator's fuel storage systems. This capacity ensures that a minimum usable volume (29,180 gallons) is available to permit operation of each of the diesel generators for approximately three days with the diesel generators loaded-l to the 2,000 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> rating of 5335 kW. The ability to cross-tie i
the diesel generator fuel oil supply tanks ensures that one diesel generator may operate up to approximately six days.
Additional fuel oil can be supplied to the site within twenty-four hours after contacting a fuel oil supplier.
j The licensee performed a' load shedding analysis which indicates that, with reduction of loads, the above minimum usable volume of 29,180 gallons of fuel i
oil in each of the fuel oil storage systems will permit a continuous operation of the corresponding EDG for approximately 5 days. With cross-connecting storage tanks, one EDG may be operated continuously for a period of well over 7 days.
During the June 22, 1994 meeting, the licensee agreed to modify the plant Emergency Plan Implementing Procedure (EPIP) to require that.the manager of the Technical Support Center, within the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following a loss-of-coolant accident (LOCA) or loss-of-offsite power (LOP) event, provide a recommendation to the station with respect to load shedding to conserve EDG fuel oil.
In the response to the staff's RAI, the licensee re-stated its commitment with regard to EDG load shedding.
In addition, the licensee indicated that the plant EPIP provides:. (a) adequate guidance related to ordering fuel oil within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of a LOCA or LOP to ensure the replenishment of fuel oil supply in a timely manner (within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the order for additional fuel oil has been placed), and (b) procedural guidance for cross-connecting storage tanks and for aligning the standby pump to the opposite train of electrical supply, if necessary.
Considering the above. cited licensee's commitments, the staff concludes that the licensee will have adequate and reliable-fuel oil inventory in the day tank for 1-hour EDG operation and in the storage tanks for 7 days of continuous EDG operation following a LOCA at Millstone 3.
Based on its review, the staff concludes that the EDG fuel oil stored at Millstone 3 meets the intent of the guidance described in ANSI N195-1976. Therefore, the staff finds the above proposed paragraph to be added to TS Bases Section 3/4.8 related to minimum fuel oil stored for Millstone 3, acceptable.
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4.0 STATE CONSULTATION
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In accordance with the Comission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment. The State official had no comments.
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5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR i
Part 20. The NRC 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, and that there is no i
significant increase in individual or cumulative occupational radiation exposure. The Comission has previously issued a proposed finding that the i
amendment involves no significant hazards consideration, and there has been no public comment on such finding (58 FR 59753). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR I
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 amendment.
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6.0 CONCLUSION
The Comission 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 comon j
defense and security or to the health and safety of the public.
t Principal Contributor:
D. Shum Date:
October 17, 1994 i
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