B14888, Proposed Tech Specs Re EDG Fuel Oil Storage Capacity
| ML20070E410 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/08/1994 |
| From: | NORTHEAST NUCLEAR ENERGY CO. |
| To: | |
| Shared Package | |
| ML20070E398 | List: |
| References | |
| B14888, NUDOCS 9407150073 | |
| Download: ML20070E410 (5) | |
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Docket No. 50-423 B14888 i
Millstone Nuclear Power Station, Unit No. 3 Request for Additional Information Proposed Revision to Technical Specifications Emergency Diesel Generator Fuel Oil Storage Capacity s.
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July 1994 i
9407150073 940708 PDR ADOCK 05000423 PDR p-
1 U.Ss Nuclear Regulatory Commission B14888/ Attachment 1/Page 1 July 8, 1994 Millstone Nuclear Power Station, Unit No. 3 1
Request for Additional Information Proposed Revision to Technical Specifications Emergency Diesel Generator Fuel Oil Storage Capacity 1.0 Provide the detailed calculations (e.g.,
calculation 91-019-152M3, etc.) which were performed to verify usable storage capacities of the EDG fuel oil storage tanks and the EDG fuel oil day tanks.
The calculations should reflect:
the increase in the post-accident electrical loads due to corrections in the calculation and improvements in the calculation methodology that have occurred since the original design calculation in 1985; instrument errors; effect of variations in fuel oil properties; and vortex formation in the EDG day tank.
Resnonse A discussion of the detailed calculations (i.e., calculation 91-019-152M3) related to the storage capacity for the emergency diesel generator (EDG) fuel oil storage tanks and EDG fuel oil day tanks was provided at the June 22, 1994, meeting.
The discussion included a description of the improvements in the calculations (the consideration of instrument
- errors, effect of variations in fuel oil properties and vortex formation in the EDG day tank) and noted the calculation included an increase in the post-accident electrical loads due to corrections in calculations.
2.0 In Attachment 1 of the letter dated June 30, 1993, NNECO indicated that:
a re-evaluation of the large break LOCA and loss of offsite power load shedding calculation would be performed to demonstrate the ability to extend the EDG run time by October 31, 1993; and the guidance for electrical load shedding would be incorporated into Emergency Plan Implementing Procedure (EPIP)
- 4400,
" Notifications and j
Communications," by July 31, 1993.
Provide the following:
the details (e.g.,
conservative assumptions, justifications for shedding each electrical load, the duration of each constant load on the EDG(s), EDG fuel oil consumption rate during the duration of each constant electrical load, and the fuel oil inventory at the beginning of each duration, etc.)
of the above cited electrical load shedding calculation.
U.S.
Nuclear Regulatory Commission B14888/ Attachment 1/Page 2 July 8, 1994 the time (following the onset of a LOCA) to initiate the electrical load shedding and each step taken to shed the electrical loads.
the location of guidance to operators (procedure numbers) to perform the following:
order fuel oil within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of LOCA; monitor fuel oil inventory; and isolate the empty fuel storage tank of one EDG and align the fuel oil transfer pump discharge header to facilitate the use of the fuel oil storage tank.
The Staff intends to review the time at which operator action for load shedding is called for in the procedures, to assure that it corresponds with the time credited for load shedding in diesel generator fuel oil consumption calculations.
Response
A re-evaluation of the large break LOCA and loss of offsite power load shedding calculation was completed in December 1993.
The details of the load calculations were presented at the June 22,
- 1994, meeting.
In
- addition, it was indicated that Emergency Plan Implementing Procedure (EPIP)
- 4400, Revision 2,
" Event Assessment, Classification and Reportability,"
provides 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 loss of offsite power (LOP).
Also, NNECO agreed to include the following in EPIP 4400:
"Within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of a
- LOP, the Technical Support Center staff will provide appropriate recommendations regarding the load shedding alternatives to the Management."
It was noted that the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in the procedure does not correspond to the 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> assumed in the calculation for the initiation of load sheddit:q.
The impact of this discrepancy on the run times was considered acceptable.
Procedural guidance to control room operators for isolating an empty fuM oil storage tank and aligning an opposite train tank to supply fuel is contained within two procedures.
In the event of a fuel oil storage tank low level
- alarm, the Alarm Response Section of Operations Procedure (OP) 3346A, " Emergency Diesel Generator," contains steps for the operator to locally manipulate valves and cycle the fuel oil transfer pumps to maintain level in the affected day tank between the high and low level alarms.
This procedure also provides guidance regarding fuel oil
l U.Ss Nuclear Regulatory Commission B14888/ Attachment 1/Page 3
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July 8, 1994 consumption rates and expected levels where fuel oil should j
be added to the storage tank to maintain minimum technical specificatica levels, prior to running a Diesel Generator.
Additionally, procedural guidance for cross-connecting storage tanks is found in OP 3346B, " Diesel Fuel Oil."
This procedure also contains instructions for aligning the I
standby pump to the opposite train electrical supply, if necessary.
Indication of both storage tank and day tank levels is available locally in the EDG room and in the control room.
Additionally, a separate " Day Tank Low-Low" alarm for each EDG annunciates locally and in the control room.
Computer points monitor storage and day tank levels and provide indication in both the control room and the Technical Support Center, for use by the Technical Support staCf.
3.0 With regard to the design of the minimum usable fuel oil storage capacity in the day tank, ANSI N195-1976 requires that each diesel shall be equipped with day or integral ta.nk 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%.
As stated in the SER and SSER-4, NNECO's licensing commitment (stated in the FSAR) that the design bases for the EDG fuel oil storage and transfer system at Millstone 3
were in accordance with ANSI N195-1976, was one of the bases for the Staff's acccptance of the EDG fuel oil storage and transfer system at Millstone 3.
In addition, Westinghouse Standard TS Bases for the day tank states that the day tank TS minimum contained volume is based on providing adequate fuel oil for a minimum of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of EDG operation at full load plus 10%.
Therefore, the make-up setpoints of the fuel oil transfer pumps should be readjusted and the Millstone 3 TS should be revised accordingly to ensure that fuel oil inventory in the day tank will be maintained to satisfy the above licensing commitment by NNECO and the guidance of ANSI N195-1976 and Westinghouse Standard TS.
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Nuclear Regulatory Commission B14888/ Attachment 1/Page 4 July 8, 1994 Resnonce A detailed discussion on the design of the minimum usable fuel oil storage capacity in the day tank was provided at the June 22, 1994, meeting.
It was agreed that the proposed change to technical specification related to fuel oil inventory in the day tank was acceptable.
However, NNECO agreed to make appropriate changes to the operating /
surveillance procedure that will require refilling of the day tank after every engine run.
This fuel capacity in the day tank will be sufficient to maintain approximately 60 minutes of operation of the EDG at the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating.
4.0 With regard to EDG fuel oil consumption rate, there are numerous discrepancies, for example:
In the safety assessment of the proposed TS change, NNECO stated that the proposed TS changes would increase the minimum volume of fuel oil required to be stored in the EDG day tank from 205 gallons to 278 gallons.
The run-time would be extended from 23 minutes to approximately 27 minutes.
From this information, one will predict the following EDG fuel oil consumption rates:
1)
[205 - (278 - 189)]/23 =
5.17 gpm 2)
[278 - 205) /(27 - 23) = 18.25 gpm In the bases for the proposed TS change, NNECO stated that 413 gallons usable volume corresponded to approximately 60 minutes of EDG operation and 284 gallons usable volume corresponded to approximately 42 minutes of EDG operation.
From this information, one will predict the following EDG fuel oil consumption rates:
1) 413/60 = 6.88 gpm 2) 284/42 = 6.76 gpm Provide clarification for the above discrepancies.
Resoonse l
A detailed clarification regarding the above discrepancies was provided at the June 22, 1994, meeting and was accepted by the NRC Staff.
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