ML20058K503

Discusses Use of Emergency Diesel Generators as Alternate Ac Source at multi-unit Sites,Per Licensee .Emergency Diesel Generator Load Mgt Methodology Evaluated to Meet Listed Criteria

ML20058K503
Person / Time
Site:	Beaver Valley
Issue date:	06/29/1990
From:	Sieber J DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9007060205
Download: ML20058K503 (11)

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.-- a Wiley Power $tation

' $Nppingport. PA 4077-0004

, P, t Neer Group p M6m June 29, 1990 j U. S. Nuclear Regulatory Commission Attn: Document Control Desk l Washington, DC 20555

Reference:

Beaver Valley Power Station, Unit No. 1 and No. 2 )

BV-1 Docket No. 50-334, License No. DPR-66 '

BV-2 Docket No. 50-412, License No. NPF-73 SBO - Alternate AC load Management i

Gentlemen:

By letter dated March 30, 1990, we provided a supplemental-response to Station Blackout'(SBO) relative to the NUMARC guidance  !

issued January 4, 1990. As part of our response, we requested a-90-day extension l to work with NUMARC and the other utilities '

affected by the guidance provided by your staff relative to the  ;

- use of emergency diesel generators (EDG's) as an Alternate AC.  ;

(AAC) source at multi-unit sites.

We. have evaluated our EDG load management methodology to 1

- ensure it meets the following criteria: i

1. Margin of safety shall not be degraded

2. Operator burden shall not be increased

3. The potential for common cause failure shall be minimized The margin of safety normally available during a safe shutdown non-DBA at the Non-Blacked Out (NBO) unit is not reduced as a result of the cross-tie. The normally available margin of safety-W is maintained by ensuring that:  !

1. The steady state and dynamic loads imposed by operation of the necessary NBO and SBO unit AC systems does not exceed the capacity of the EDG being used-to supply AAC power.

2. The resulting configuration does not involve an unreviewed safety question as defined by 10 CFR 50.59.

g 9009060205 900629 0 PDR ADOCK 050003P4 i p FDC 1

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edvCr Valloy Pow 0r Station, Unit No3. 1&2 B

Docket No. 50-334, License No. DPR-66 Docket No. 50-412, License No. NPF-73 SBO - Alternate AC Load Management Page 2 The actions necessary to provide power to the SBO unit will not increase the burden on the NBO unit's operators based on:

1. Operator actions necessary to ensure the process of supplying AAC power to the SBO unit is held to a minimum and does not endanger-the reliability and dependability of the NBO unit's Emergency AC (EAC) power supply, i

2. Manpower _ requirements to manage loads at the NBO unit can be

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accomplished with the normally available staffing level.

3. Operators are not required to take actions that could damage or permanently disable components that are needed to respond to a normal loss of off-site power (non-DBA).

This criteria does not preclude operators from taking reasonable actions, as may be required and permitted under 10 CFR 50.54(x) and (y), should plant conditions depart from the assumptions and considerations defined for a station blackout.

NUMARC 87-00 Appendix B provides criteria for minimizing the risk of dependent failures. We have evaluated the proposed Alternate AC configuration against the guidance in NUMARC 87-00 Appendix B. An

' evaluation, demonstrating the criteria requirements are satisfied, is available on site for review.

Design features and design control measures will be implemented to ensure the EDG is capable of powering the full complement of loads that are normally required during a safe shutdown (non-dBA). Loads for cystems whose function would only be needed during a design basis .

accident are not considered since the NBO unit is assumed to maintain a normal (non-dBA) safe shutdown.

Protective features will be implemented to ensure that electrical faults in the SBO unit will not propagate to the NBO unit, and that the necessary static -and dynamic loading will not prevent the AAC power source from performing its intended safety function.

The UFSAR will be revised to reflect the final design loading scheme and protective measures for SBO. This revision will be submitted as part of the annual update following completion of the p modification. The UFSAR revision will identify the complete L complement of equipment needed to achieve and maintain a loss of L off-site ~ power safe shutdown as identified in Tables 1 and 2 of-the Enclosure. This revision will not affect in any way the components necessary for responding to a DBA. A safety review will be performed in accordance with the requirements of 10 CFR 50.59 as part of the UFSAR revision process.

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.. Beivcr Vcllcy Pow 3r Stttion, Unit Nos. 1 & 2 Docket No. 50-334, License No. DPR-66 Docket No. 50-412, License No. NPF-73 SBO - Alternate AC Load Management

,Page 3 Enclosure 1 "AAC Load Management Scheme for Beaver Valley" provides the methodology for achieving AAC for both Beaver Valley Unit 1 and Unit 2. The proposed load management scheme ensures the non-blacked out unit is brought to and maintained in a safe shutdown condition which meets the SBO regulatory requirements.

Differences in the assumptions for loss-of-offsite power loads from those currently specified in the UFSAR have been identified with justifications provided in the enclosure.

The- modifications and procedure changes associated with the AAC cross-tie will be completed. within two years after the notification provided by the Director, Office of Nuclear Reactor Regulation in accordance with 10CFR50. 63 (c) (3) . Since our Alternate AC (AAC) power source will involve cross-tieing busses between Units 1 and 2, installation and testing will require refueling outages at both units to fully implement the cross-tie.

capability. Therefore, the schedule for completion-may need to be extended, dependent on the NRC approval date and the scheduled l

refueling outage dates for both Unit 1 and 2. Presently, the l schedule for Unit 2's 3rd Refueling Outage is March 1992, and Unit l's 9th Refueling Outage is September, 1992.

If there are any questions on this matter, please contact my i office. ,

Very truly yours, L h I

d. D. Sieber l ' ice President Nuclear Group '

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cc: Dr. T. Murley, Director of Office of NRR Mr. J. Beall, Sr. Resident Inspector Mr . 10. T. Martin,.NRC Region I Administrator l Mr. A. W. DeAgazlo, Project Manager Mr. R. Saunders (VEPCO)

NUMARC l

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ENCLOSURE I i Page 1 l ALTERNATE AC LOAD MANAGEMENT SCHEME FOR BEAVER VALLEY Beaver Valley.is a two unit site utilizing an EAC source available from the non-blacked out unit (NBO) as an Alternate AC (AAC). The system meets the AAC criteria discussed in Appendix-B of NUMARC 87-00, and is capable of supplying the necessary safe shutdown loads of both units. Since the Unit 2 diesels are considerably larger, a substantial amount of excess AAC power is available to I cope with a blackout in Unit 1. For this reason, this discussion focuses on the more limiting scenario where the excess capacity from the Unit 1 diesel will be supplying AAC power for Unit 2.

As defined in Appendix A of NUMARC 87-00 document, Station Blackout (SBO) is the complete loss of AC electric power to the essential and nonessential switchgear buses in a nuclear power plant (i.e., loss of off-site electric power system concurrent with turbine trip and unavailability of the on-site emergency AC power system). SBO does not include the loss of available AC '

power to buses fed by station batteries through inverters or by Alternate AC power sources, nor does it assume a concurrent single failure or a design basis accident. At a multi-unit site with normally dedicated emergency AC power sources, station blackout is assumed to occur in only one unit.

The excess capacity that may be used as AAC power for.an adjacent

-blacked out unit is defined as the capacity, within the allowable EDG rating, for the expected SBO duration but above the power requirements for normal Loss of Offsite Power (LOOP) safe shutdown functions. Electrical loading necessary to support the normal LOOP safe shutdown functions may vary during the required SBO coping duration.

The maximum AC power requirements needed during a LOOP are shown in UFSAR ' Table 8.5-1 for Unit 1 and Table 8.3-3 for Unit 2. The Unit 1 proposed safe shutdown methodology during a LOOP concurrent with a station blackout in Unit 2, is generally consistent with the FSAR discussion. For the most part, all systems indicated in the FSAR table are expected to be available during a station blackout of the adjacent unit. However, some of the equipment listed in the table are not generally powered within the expected duration of the station blackout or do not have a safety function during a loss of off-site power. The NBO unit's safe shutdown capability is not degraded by employing this shutdown methodology. In addition, the flexibility normally available to the operators is not expected to be constrained.

The sections below describe the proposed load management scheme in detail highlighting an; differences from the load list shown in the FSAR. Three time periods are discussed: (i) the first hour, (ii) the following three hours, and (iii) an extended duration

.beyond four hours. As discussed in NUMARC 87-00 and Regulatory Guide- l'.155, AAC power only needs to be available during the second period (item (ii)).

ENCLOSURE I Page 2 i

ALTERNATE AC LOAD MANAGEMENT SCHEME FOR BEAVER VALLEY i The loss of off site power load management scheme is summarized in  !

Table 1. This loading is sufficient to maintain the NBO unit in a ,

safe shutdown condition for an extended duration well beyond four j hours. Beyond the duration of the SBO, the NBO unit will retain. '

the capability to support its loss of off site power safe shutdown  !

loads. The AAC power system is adeq.,'aly sized to carry the required shutdown loads for the requAred coping duration ,

maintaining voltage and frequency within limits consistent with the ect ablished industry standards. Also, the loading arrangement i will not degrade the performance of any shut down systems or components.

Loads Available During The First Hour l During the first hour of the event, all' applicable loads identified in the FSAR table may be powered. This includes all loads that are automatically loaded onto the diesel generators as indicated in Table 8.5-1 of the FSAR.

t Loads Available After One Hour and Before Four Hours I After the first. hour, a degree ci load management is necessary to ensure adequate Alternate AC power is available to the blacked out ,

unit. These loads fall into three categories: (a) loads that are not generally powered within the expected duration of the. station blackout, (b) loads that are not required to ensure safe shutdown capability, and (c) loads that do not have a safety function.

a. Loads that are not aenerally oowered within the exoected duration of the station blackout i

It is important to note that some safe shutdown loads are only normally needed during the first hour of the transient, or l considerably after four hours. These loads include motor operated valves, and the spent fuel pool cooling system.

Power for motor operated valves, will only be needed during i

the first ten minutes to realign safety systems. Since these components are not normally energized after the f'.rst hour of the event, they do not need to be powered after the first hour, i

i The spent fuel pool cooling pumps will not need to be powered l until after the coping period for a loss of off site power.

l Thus, it is not necessary to consider this load during the four hour duration of a station blackout.

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1 ENCLOSURE I l Page 3 H f ALTERNATE AC LOAD MANAGEMENT SCHEME FOR BEAVER VALLEY 1

The Leak Collection exhaust fans, although automatically loaded on the EDG for a loss-of-offsite power event, are I primarily to prevent radioactive' leakage from the containment and contiguous areas following -a DBA. The system provides L ventilation to the- Aux FW-pump room which was analyzed for a loss of ventilation under SBO criteria. Therefore, this load is not needed for normal safe shutdown following a loss-of- <

g offsite power event with no concurrent failure or DBA type .(

l events.

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b. Loads that are not reauired to ensure safe shutdown canability Several loads are not needed for normal safe shutdown following a loss of off site power. These include the L

containment air recirculation fans, and the containment instrument air compressors. The unavailability of' these systems during this period will not reduce the information available to the operators to monitor the safety related conditions of the plant, nor will it impair or damage the NBO unit in any way, b.1 Containment ventilation cooling water is not safety related at Beaver Valley. Thus, the containment recirculation fans would not serve their cooling function and would only add to the heat generation. This condition- has been ' analyzed and verified during plant operation. Containment temperatures have been shown to not- increase beyond 110*F during the first four hours of the event. This temperature is considerably below the EQ' operability limit of 135'F.

b.2 Similarly, cooling water for the containment instrument air -compressor is not safety related, and consequently is normally unavailable during a loss of off-site power.

For this reason, the compressor must be disabled since operation without cooling results in an electrical trip of the component. Existing plant procedures for coping with a LOOP event direct operators to disable the compressor for a loss of cooling water resulting from the loss of off-site power. This system is not required to ensure safe shutdown capability.

I LER 84-07 Loss of Containment Cooling

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ENCLOSURE I I I

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ALTERNATE AC LOAD MANAGEMENT SCHEME FOR BEAVER VALLEY

c. Loads that do not have a safety function The turbine generator bearing lube oil pump, and the turbine bearing oil lift pump are used during and after turbine coastdown (approximately thirty minutes). However, these are non-safety related loads and are not required for the safe shutdown of the plant. The turbine turning gear drive, which is used to prevent turbine shaft warpage, is also not required for safe shutdown. The turning gear.will not be available unless Emergency Diesel Generator No. 1 is op3 rating since power is provided from only one emergency potter train.

Loads Available After Four Hours The station blackout rule only requires Alternate AC power to be provided for the station's required coping duration. Thus, after '

L four hours, Unit i no longer needs to supply AAC power to Unit 2.

However, as discussed above, the proposed loading arrangement is  !

sufficient to maintain the station in a safe condition for an extended duration beyond four hours.

EOP Develooment and Methodolocy Procedures (EOP's) will be developed to allow for discretionary

. loads- for operator flexibility of load management dependent on sufficient EDG capacity. The addition of a high-head charging.

pump to the blacked-out unit would be one such example.

Both- beaver Valley units are equipped with 100% capacity turbine driven AFW pumps. -Irrespective of the turbine driven AFW pump, sufficient design capability is available to power the motor-driven AFW pump at' the HBO unit during this event. (See Table 1). ,

Eggmary and Conclusion J.

The load management scheme discussed above ensures the NBO unit is brought to and maintained in a safe shutdown condition for an extended period well beyond four hours. No component is permanently disabled or in any way degraded. In fact, load management is needed to ensure long term operability of equipment. On this basis, we find that this arrangement meets the current SBO requirements.

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[ TABLE 1 Alternate AC Lond Management Scheme For Seaver YetLey

!. (Total Londs on Unit i EDC) i UNIT 1 UNIT 2

. COMPONENT LOADS (kW) LOADS (kW)

- NBC Unit 80 Unit Remarks 0 to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to- After 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to i hour 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 4 heure 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />

[ Charging-Ni Need S a f e t.y 442.0 442.0' 442.0 *(477) l Infection Pumn River Water Pumn 338.0 338.0 338.0 (+) + Cross-tie RUS Stoes Generator AFW 302.0 302.0 302.0

'Puno Primary ~ Plant component- 221.0 221.0 221.0 j' Esolina Water Pumn

' Turbine Bearing Ott' 13.0 0.0 0.0 See section C Lift Puno Motor Onorated Vatves _

53.0 0.0 ,

0.0 , see section a EQorgency Diesel 28.0 28.0 28.0 l Auxillaries l Turbine. Generator 39.0 0.0 0.0 See section C l

Liarina Lube oft Pump Turbine-Turning Gear 39.0 0.0 39.0 grive _ _ ,

Pressurizer Nesters ** 0.0 216.0 216.0 ** One hour detav Boric Acid' Transfer Puen 13.0 13.0 13.0 ,

Boric Acid T a fi k Nesters 15.0 15.0 15.0 Battery Charmers 38.0 14.6 3 8 . 0 __ 3821__

Ecorgency Lighting 5.0 5.0 5.0

'Suontementat __

l Ecorgency Lighting 28.0 28.0 28.0 j sunotementet containment Air 283.0 0.0 0.0 See Section b.1 Recirculation Fans Control Room Air 48.0 48.0 48.0 Sucoly Fans control Roos Air Return 25.0 25.0 25.0 fans control Room AC 61.0 61.0 61.0 gamoressors t -Control Room AC 4.0 4.0 4.0 Condenser circulating Pumps Lock Cottection Exhaust 115.0 0 0 See section a

j. Fans I' Safeguards-Area Sump 4.0 4.0 4.0 L Egan Ecorgency Swgr & 8.0 8.0 8.0 Battery Room Exhaust Fan Ecorgency Swgr & 13.0 13.0 13.0 sottery Room Supply Fan Fuel Poot Coottna Puno 2 0. 0_ _ 0.0 20.0 Sye section o

• Discretionary (EOP) Load

• • Intermittent Lomd; Pressurfter heaters to be de-energized when starting discretionary load (cherging pump) et eV-2. To be proceduralty addressed.

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TAELE 1 (Cent.)

Alternate AC Loed Management Schsee For Beaver Vattey (Total Loeds on Unit 1 EDG)

UNIT 1' UNIT 2 COMPONENT. LOADS (kW) LOADS (kW) l ,

NB0 Unit 50 Unit temarks 0 to I hour to After 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to j 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> see '

Control Rod Cooting 81.0 81.0 81.0 56.0 Fan Miscettaneous Fans, 13.0 13.0 13.0 Damners. and Punos Miscettaneous Fans, 10.0 10.0 1 0 . .'

Despers_ and Punos Ll o e Neat Tracina 60.0 60.0 60.0 Ploe Meat-Tracina 60.0 60.0 60.0 Vital Bus ioads 50.0 50.0 50.0 N!scelteneous Neaters 62.0 62.0 62.0 Miscelteneous Neaters 12.0 12.0 12.0 Ecorgency AC 11.0 11.0 11.0 D i s t r i b u t ', o n Panels

'Ecorgency AC 22.0 22.0 22.0 Distribution Panets containment Instr. Air 17.0 0.0 0.0 See Coction b.2 Comoressor LLaguter Inverter 17.0 17.0 17.0 48 Volt Battery Charmer 5.0 5.0 5.0 Additional SB0 loads for B0 Unit Control Room MVAC 27.4 Fan-only Unit (BV-2)

Lead & Cooling System 49.0 Losses AC Dist. Transf.

AC Dist. Transf. 0.3 AC Dist. Transf. 3.1 AC Dist. Transf. 0.3 I AC Dist. Transf. 5.1  ;

Vital Bus Rect. 2-3 8.8 Vital Bus Reet. 2-1 14.0 l Bettery Room Enhaust 6.2 Fan l AC Distr. Infr 2.9 AC Distr. aufr 2.1 l ljTAL LOADS 2585.0 2222.0 2396 666.8* tincludes TOTAL LOADS ON Chg Pump)

UNIT 1 EDG 2585.0 2888.8 2396 j 1

1 NOTE: Olesel generator 168 hour0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> capartty = 2950 kw.(Ref. UFSAR-1, Fig. 8.1-1

' Design capability does exist for powering the discretionary load j (charging pump) at the 5.0. Unit.

I l A single CRDM shroud fan is sufficient during the first four hours for upper-head cooling per E0Ps and engineering evaluation.

Reference EM No. 22241.

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• i TABLE 2 Alternate AC Loed Management Scheme For Besver Valtey l (Totat Loeds on Unit 2 EDG) l l

UNIT 2 UNIT 1 COMPONENT LOADS (kW) LOADS (kW) l NBC Unit 80 Unit temarks l 0 to I hour to After 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to l 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> l Chorging*NI Need Safety 477.0 477.0 477.0 *(442) l

! Infection Puen

! Service Water Pumn 696.0 696.0 696.0

. Steam Generator AFW 320.0 320.0 320.0 Puen Primary Plant Component 316.0 316.0 316.0 Coottna Water Puen Leak Cotol. Fitter 150.0 150.0 150.0 Exch. Fans Ecore. Supr. Supply 50.4 50.4 50.4 Fans E30rg. Sver. Exch. 44.9 44.9 44.9 Fans pain st;am Fans 62.0 62.0 62.0 ,

cont. .

Rectrc. Fans 154.0 0 0 See section b.1 Lesk Syn. Elec. Wtr. 211.0 211.0 211.0 Press. Nesters 0.0 270.0 270.0 One Nour Detav CRON'throud Fan 56.0 56.0 56.0 81.0 See Note 1' Lood &'Clg. Sys. 49.0 49.0 49.0 l Losses (XFNR)

AC Dist. Transf. (E*S) 0.3 0.3 0.3 SWP Lube Water Strainer 0.5 0.5 0.5 l Intake suontv Fan 4.1 4.1 4.1 AC Dist. TRansf. (E.3) 3.1 3.1 '.1 l-Control Re. AC Unit 27.4 27.4 27.4 61.0 '

Refria. Cond. Unit 50.0 50.0 50.0 AC Dist. Transf. (E-9) 0.3 0.3 0.3 Elec. Heat Xfar. 2.1 2. 2.1 __

Motor Operated Vetves 110.6 0 0 (total)

Fuel Pool Coolina Pump 14.4 0 14.4 cent. Btdg. Air Exch 25.0 25.0 25.0 and Supotv Fan Chg. Pump Cub. 18.0 18.0 18.0 Exch. Fan AC Dist. Transf. (E-1) 5.1 5.1 5.1 NCC Cub.-Emch. Fan 2.8 2.8 2.8 DG Fuet Olt Xtr. Pumps 0.7 0.7 0.7 DG stdg. Supply Fan 33.0 33.0 33.0 (270A)

DG Crank. Lase 1.1 1.1 1.1 Vacuum Pump

• Discretionary (EOP) Loud

• • Intermittent Lond

TABLE 2 (Cont.)

Attornate AC Lond Nanagement Scheme For Beaver Valley (Total Loeds on Unit 2 EDG)

UNIT 2 UNIT 1 COMPONENT LOADS (kW) LOADS (kW)

Vital Bus Rect. 0.8 8.8 8.8 DE BLde. Supply Fan 30.0 30.0 30.0 (271A)

DG BLda. Exch. Fan 0.7 0.7 0.7 DG Pretube Puan 0.55 0.55 0.55 SG Area A/C Unit 16.5 16.5 16.5 Vital Bua tect. 2-1 14.0 14.0 14.0 CV & RC Area A/C Unit 18.4 18.4 18.4 Boric Acid Trana. Puen 13.16 13.16 13.16 Batterv Room Each. Fan 6.2 6.2 6.2 6.2 Recirc. Puso (25Ws*P25A) 1.0 1.0 1.0 AC Llat. Transf. (E-7) 2.9 2.9 2.9

.AC Olst. Transf. (E-11) 2.1 2.1 2.1 Aux FW Control Valves 1.05 1.05 1.05 ___

Atp. Ste. Dump Valvos (101A.B & C) 1.05 1.05 1.05 Battery Charmer 14.6 14.6 14.6 38.0 River Water Puen (Unit 1) 338.0 Cont. Ra.-Supply & 73.0 Emh. Fans (Unit 1)

E. Swar. & Battery Ra 21.0 Suontv & Euh. Fana. (Unit 1) _

(Inctudes TOTAL LOADS 3015.8 3006.8 3 0 2 1 .'2 1060.2* Chn. Puno)

TOTAL LOALS ON UNIT 2 EDG 3015.8 4067.0* 3021.2 NOTE: Diemet generator 160 hour0.00185 days <br />0.0444 hours <br />2.645503e-4 weeks <br />6.088e-5 months <br /> capacity = 4662 kw.(Ref. UFSAR-2, Section 8.

• Design capability does exist for powering the discretionary Lond (charging pump) at the 8.0. Unit.

' A single CADM shroud fan is sufficient during the first four hours for upper head cootIng per ECPs and engineering evatuation.

Reference EM No. 22241.