B15053, Application for Amend to License DPR-65,revising TS Re EDG Fuel Oil Supply

Application for Amend to License DPR-65,revising TS Re EDG Fuel Oil Supply

ML20077F149
Person / Time
Site:	Millstone
Issue date:	11/30/1994
From:	Opeka J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES SERVICE CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20077F153	List: B15053, Application for Amend to License DPR-65,revising TS Re EDG Fuel Oil Supply ML20077F154
References
B15053, NUDOCS 9412130278
Download: ML20077F149 (8)

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Northeast Utaties Service Cornpany l P.O. Ik)x 270 l Ilartford, CT 06141-0270 (203) 665 5000 November 30, 1994 Docket No. 50-336 B15053 Re: 10CFR50.90 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Millstone Nuclear Power Station, Unit No. 2 Proposed Revision to Technical Specifications Emeraency Diesel Generator Fuel Oil Sunnly Tntroduction Pursuant to 10CFR50.90, Northeast Nuclear Energy Company (NNECO) hereby proposes to amend its Operating License, DPR-65, by incorporating the changes identified in Attachments 1 and 2 into the Millstone Unit No. 2 Technical Specifications. NNECO is proposing to add a footnote to Limiting Conditions for Operation (LCOs) 3.8.1.1.b and 3.8.1.2.b which will denote that 24,000 gallons of fuel oil is capable of supporting the operation of one emergency diesel generator (EDG) for at least four days and the other EDG for one hour with the EDGs loaded to the continuous rated load of 2750 kW. The intent of this proposal is to change the design basis requirements regarding the EDG fuel oil supply.

Backaround The Millstone Unit No. 2 Final Safety Analysis Report (FSAR) contains several requirements regarding the amount of fuel oil required to be stored onsite to support the operation of the EDGs.

Section 8.3.1.2 states that the EDGs and their associated devices are designed, built, and tested in accordance with Section 5.2.4 of IEEE Standard 308-1971, " Class IE Electric Systems for Nuclear Power Generating Stations." Additionally, Section 8.3.2.2 of the FSAR states that "the combined capacity of the diesel oil supply tanks is sufficient for one diesel generator to operate for approximately seven days plus the other diesel generator for one hour following a LOCA."

Additional statements regarding the amount of EDG fuel oil that is required to be stored onsite are contained in the NRC Staff's safety evaluation report (SER) dated May 10, 1974. In the SER, the NRC concluded that the EDGs satisfied IEEE Standard 308, and that the design of the EDG fuel oil system assured that a minimum of at least several days of diesel oil inventory would be available for operation of one EDG loaded to full capacity.

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l d.S. Nuclear Regulatory Commission B15053/Page 2 November 30, 1994 The references in the FSAR and SER to IEEE Standard 308 are significant because the standard contains recommendations regarding the volume of fuel oil which should be stored onsite. Section 5.2.4 (6) of IEEE Standard 308-1971 states:

" Stored encrgy at the site shall have capacity to operate the standby power supply while supplying post-accident power requirements to a unit for the longer of the following:

(a) seven days (b) time required to replenish the energy from sources away from the generating unit's site following the limiting design basis event" For Millstone Unit No. 2, this implies that the fuel oil system should be capable of supporting the operation of an EDG for seven days at post-accident loads.

A revised engineering calculation determined that the inventory of safety-related EDG fuel oil (24,000 gallons) was sufficient to support EDG operation for 6.17 days with the EDG supplying post-accident loads. This conclusion is not consistent with the original design basis of Millstone Unit No. 2 as stated in the FSAR and the SER dated May 10, 1974. Thus, a determination was made that Millstone Unit No. 2 was not in compliance with the statement in the FSAR and the SER regarding compliance with IEEE Standard 308-1971.

In a Licensee Event Report submitted on August 19, 1994,(u NNECO explained the cause of this noncompliance, and committed to resolve the EDG fuel oil storage issue by proposing a change to the Millstone Unit No. 2 technical specifications.

Descrintion of Pronosed Chances NNECO is proposing to add the following footnote to LCOs 3.8.1.1.b and 3.8.1.2.b of the Millstone Unit No. 2 Technical Specifications:

"The total capacity of 24,000 gallons ensures that one diesel ,

generator may operate for at least four days, while the other diesel generator may operate for at least one hour. These run-times assume that the diesel generators are loaded to 2750 kW (the diesel generator continuous rated load.)"

(1) D. B. Miller, Jr. letter to the U.S. Nuclear Regulatory i Commission, " Facility Operating License No. DPR-65, Docket No. l 50-336, Licensee Event Report 94-020-00," dated August 19, i 1994.

U.S. Nuclear Regulatory Commission B15053/Page 3 November 30, 1994 Additionally, NNECO is proposing to provide additional information in Bases Section 3/4.8 regarding EDG run-times and the capacity of the EDG fuel oil system.

Safety Assessment The proposed changes to LCOs 3.8.1.1.b and 3.8.1.2.b and Bases Section 3/4.8 will revise Millstone Unit No. 2 design requirements regarding the volume of EDG fuel oil which is required to be stored onsite. Currently, the Millstone Unit No. 2 EDG fuel oil system is required to support the operation of an EDG for seven days with the EDG supplying post-accident loads.

Millstone Unit No. 2 has two separate and independent EDGs, each with a separate fuel oil supply tank containing a minimum of 12,000 gallons of fuel oil. These tanks can be cross-connected so that a total inventory of 24,000 gallons would be available to one or both EDGs. Additionally, the EDG fuel oil supply tanks can be replenished via onsite and offsite sources.

A calculation was performed to determine the length of time that the EDGs could operate based on the total inventory of safety-related EDG fuel oil available (24,000 gallons) , fuel consumption ,

rates provided by the EDG manufacturer, and current post-accident i EDG electrical loading which took into account load shedding based on equipment operation governed by present procedures. It concluded that the EDG fuel oil inventory could support the operation of one EDG for 6.17 days with the other EDG running for one hour. This calculation did not consider replenishment. Based on this calculation, the requirements of IEEE Standard 308-1971 could not be met. The reduction in EDG run-time can be attributed to a higher and more conservative EDG fuel oil consumption rate, and an increase in the electrical loads served by the EDG.

A second calculation was performed to determine the length of time that the EDGs could operate given a continuous rated load of 2750 kW. It concluded that the safety-related EDG fuel oil inventory could support operation of one EDG for at least four days with the other EDG running for at least one hour. Once again, replenishment was not considered. ,

Incorporating the second calculation as the new design basis of Millstone Unit No. 2 would provide additional operational flexibility, since the EDG loading could be varied without I compromising the EDG run-time. While this does not satisfy the '

recommendations of IEEE Standard 308-1971, it does satisfy the NRC Staff's statement in Section 9.6.2 of the SER dated May 10, 1974.

In this section, the NRC Staff stated that the EDG fuel oil system would assure that a minimum of at least several days of EDG oil

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4 U.S. Nuclear Regulatory Commission B15053/Page-4 November 30, 1994 inventory would be available for one EDG loaded to full capacity.

Also, in actuality, the EDG would run for a duration significantly greater than four days since the actual loading on the EDG is less than tho continuous rated load of 2750 kW and the electrical loads would be shed through normal recovery actions following an accident.

A four day EDG run-time provides a significant margin of time for replenishment of EDG fuel oil. Replenishment can be accomplished from the nonsafety-related underground storage tank or offsite sources. The underground storage tank provides the normal make-up p.ath for fuel oil to the fuel oil supply tanks. It contains fuel o'il which is fully qualified and tested regularly. In the event of a seismic event, the fuel oil stored in the underground storage tank could not be relied upon, because the underground storage tank is not seismically qualified. However, replenishment of fuel oil could be accomplished via an offsite source. Emergency Plan Implementing Procedure (EPIP) 4400 requires an evaluation of the need to order EDG fuel oil to extend onsite capacity within four hours of a loss of offsite power event.

Additionally, the high reliability of the electrical grid and the high probability that offsite power would be restored within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> reduces the need to rely on extended EDG operation.

The probability of a loss of offsite power event which lasts longer than eight hours was determined to be approximately 9.0E-04/ year.

Thus, the probability of having a loss of offsite power event which lasts longer than four days is conservatively estimated as less than 9.0E-04/ year. However, extreme environmental conditions such as hurricanes and earthquakes could induce an extended loss of offsite power.

The progress of hurricanes is monitored. Also, Abnormal Operating Procedure 2560, " Storms, High Winds and High Tides," requires the plant to be shutdown if the wind speed is forecasted to exceed 90 miles per hour within four hours of the Millstone site. Therefore, if a loss of offsite power occurred due to a hurricane, the plant would be in a shutdown condition (decreased load requirements for the EDGs). The probability of having winds that exceed 90 miles per hour is approximately 1.0E-04/ year.

The probability of a seisnic event which would induce a loss of offsite power was calculaced to be approximately 1.0E-04/ year.

After a seismic event, fuel oil could be replenished via offsite sources. Offsite power is susceptible to damage from a larger range of seismic events than are local roads and bridges. The probability of seismic events which would affect local roads and j bridges is low. In the event of a high magnitude earthquake l

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U.S. Nuclear Regulatory Commission B15053/Page 5 November 30, 1994 damaging local roads and bridges, fuel oil could be flown in within the four day period.

Based on the above, the proposed changes to the Millstone Unit No. 2 Technical Specifications do not affect public health and safety.

Sionificant flazardsl onsideration In accordance wit h 100FR50.92, NNECO has reviewed the attached proposed changes and has concluded that they do not involve a significant hazards consideration. The basis for this conclusion is that the three criteria of 10CFR50.92 (c) are not compromised.

The proposed changes do not involve a significant hazards consideration because the changes would not:

1. Involve a significant increase in the probability or consequences of an accident previously evaluated.

The proposed changes to LCOs 3.8.1.1.b and 3.8.1.2.b and Bases Section 3/4.8 will revise the Millstone Unit No. 2 design requirements regarding the volume of EDG fuel oil which is required to be stored onsite. The new rationale indicates that 24,000 gallons of safety-related fuel oil would support the operation of one EDG for at least four days with the other EDG running for at least one hour. These run-times assume the EDGs are loaded to the continuous rated loading of 2750 kW.

The proposed changes have no effect on EDG operation and reliability. They provide additional operational flexibility, because the EDG loading can be varied without the EDG minimum run-time being altered. Also, an EDG run-time of at least four days provides significant time to replenish fuel oil from onsite and offsite sources even in the event of a hurricane or >

seismic event.

Based on the above, there is no effect on the probability or consequences of an accident previously evaluated.

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U.S. Nuclear Regulatory Commission B15053/Page 6 November 30, 1994

'2. Create the nossibility of a new or different kind of accident from any accident oreviousiv evaluatqd.

The EDGs are required to operate in response to a loss of offsite power. The proposed changes to LCOs 3.8.1.1.b and 3.8.1.2.b and Bases Section 3/4.8 do not change the manner in which the EDGs respond to a design basis accident. Also, the proposed changes do not introduce any new failure mechanisms.

Therefore, the proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Involve a sianificant reduction in a marain of safety.

The proposed changes to LCOs 3.8.1.1.b and 3.8.1.2.b and Bases Section 3/4.8 have no effect on EDG operation and reliability.

They provide additional operational flexibility, because the EDG loading can be varied without the EDG minimum run-time being altered.

An EDG run-time of at least four days provides significant time to replenish EDG fuel oil via onsite or offsite sources even in the event of a hurricane of seismic event. EPIP 4400 requires that the need to order EDG fuel oil be evaluated within four hours of a loss of offsite power event. Also, the high reliability of the electrical grid and the high probability that offsite power would be restored within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> reduces the need to rely on extended EDG operation.

Millstone new Unit No. 2 has more margin than is indicated by the.

design requirements. The EDG run-time will be significantly greater than four days, because the electrical loading on the EDGs will be less than the continuous rated loading, and electrical loads will be shed through normal recovery actions following a design basis accident.

Based on the above, the proposed changes do not involve a significant reduction in the margin of safety.

The Commission has provided guidance concerning the application of the standards of 10CFR50.92 by providing certain examples (51 FR 7751, March 6, 1986) of amendments that are not considered likely to involve a SHC. While the proposed changes to LCOs 3.8.1.1.b and 3.8.1.2.b are not enveloped by any of the examples, the proposed cnanges do not involve a significant hazards consideration. The new design basis regarding fuel oil supply is sufficient sources. to permit replenishment from either onsite or offsite Also, the fuel oil system is capable of supplying the diesel generator for a longer period of time because the load used l

o U.S. Nuclear Regulatory Commission B15053/Page 7 November 30, 1994 in the calculation is very conservative, load shedding will be used following a design basis accident, and additional capacity is stored onsite in an underground storage tan!..

Environmental Considerations NNECO has reviewed the proposed license amendment against the criteria of 10CFR51.22 for environmental considerations. The proposed changes do not increase the types and amounts of effluents that may be released offsite, nor significantly increase individual or cumulative occupational radiation exposures. Based on the foregoing, NNECO concludes that the proposed changes meet the criteria delineated in 10CFR51.22 (c) (9) for a categorical esclusion from the requirements for an environmental impact staterant.

Nuclear Review Board The Millstone Unit No. 2 NRB has reviewed and concurred with the above determinations.

State of Connecticut In accordance with 10CFR50. 91 (b) , we are providing the State of Connecticut with a copy of this proposed amendment to ensure their awareness of this request.

Schedule Recuired for NRC Acoroval Since this proposed license amendment is not required to support continued safe opcration or to permit startup of Millstone Unit No. 2, NNECO is not requesting any particular schedule for NRC review and approval.

If the NRC Staff should have any questions or comments regarding this submittal, please contact Mr. R. S. Peterson at (203) 440-2074. We will promptly provide any additional information the NRC Staff may need to respond to this request, and we appreciate your efforts in support of this request.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY J. FL Opbka b bd.-

L Executive Vice President cc: See Page 8.

U.S. Nuclear Regulatory Commission B15053/Page 8 November 30, 1994 cc: T. T. Martin, Region I Administrator G. S. Vissing, NRC Project Manager, Millstone Unit No. 2 P. D. Swetland, Senior Resident Inspector, Millstone Unit Nos. 1, 2, and 3 Mr. Kevin T.A. McCarthy, Director Monitoring and Radiation Division Department of Environmental Protection

~79 Elm Street P.O. Box 5066 Hartford, CT 06102-5066 Subscribed and sworn to before me this J6 #! dayofhntga/pu , 1994 c Y v e_ n n . Y dun $r Date Commissio Expires: . 3/ 7f