Text

Forwards Response to NRC 920116 Request for Addl Info on Recommendations Presented in Station Blackout Analysis. Calculation SR-88-001,Rev 0 Also Encl
	ML20094M374
Person / Time
Site:	Wolf Creek
Issue date:	03/24/1992
From:	Rhodes F; WOLF CREEK NUCLEAR OPERATING CORP.
To:	; NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20094M377	List: ML20094M374; ML20094M380;
References
	ET-92-0072, ET-92-72, NUDOCS 9203310189
	Download: ML20094M374 (8)
	v • d • e

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WM.F CREEK

' NUCLEAR OPERATING CORPORATION Forrest T. Flhodes Vice Provident Engineerep & Tectrucal Services March 24, 1992 ET 92-0072 U. S. Nuclear Regulatory Commission ATTN:

Document Control Desk Mail Station P1-137 Washington. D. C.

20555

Reference:

Letter dated January 16, 1992, from W. D. Reckley, NRC, to B. D. Withers, WCNOC Subjects-Docket No'_50-482:

Response to Request For Additional Information on the Station Blackout Analysis for the Wolf Creek Generating Station Gentlemen:

l' L

The purpose of this letter is to submit Wolf Creek Nuclear Operating Corporation's (WCNOC) response to a Request For Additional Information contained in-the Reference.

The response to each of the Reference's recommendations are presented in the Attachment.

If you have any. questions concerring this matter, please contact me or Mr. S. G. Wideman of my staff.

Very truly yours, y)"

Forrest T. Rhodes Vice President Engineering & Technical Services FTR/aem Attachment

-cci A. T. Howell (NRC),-w/a R. D. Martin (NRC), w/a G.'A. Pick (NRC), w/a

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W. D. Reckley (NRC), w/a

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9203310189 950324

.O. Box 411/ Burlington KS 66830 I Phono- (316) 364 8631 DR ADOCK 05000402 An Equal OppmturWy Ernpiover M F4HC/ VET k

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4 Attaciunent I to ET 92-0072 Page 1 of 7 Response to Requent. frr Additional Information On The Station Bl. kout Analysis For Wolf Cteek Cenerating Station

1) Sections 2.1 and 2.2 - Tornado Frequency For the seanous stated above, the licensee needs to 2.1 Reconsnetulation chany,e the EDG reliability target frtun 0.95 to 0.975 in order to res.aln a 4 i

hour SB0 coping duration plant. The EDG target teliability change should be included in the documentation supporting the SB0 sulaulttals that le to be maintained by t.he licensee. Alternatively, the licensee needs to change the coping duration to 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months and reevaluate tha plant for an 8-hour copine, duration.

The licent.ee needs to conform to the 4-Nntr coping 2.2 Reconsnendation duration by increasing the KDG reliability target frtan 0.95 to 0.975.

Othenvise, the licensee needs to reevaluate the plant for an 8-hour coping duration and sulanit the supporting, analyees for NRC review.

Ergponse:

Ao provided in NUMARC 8? 00,

'Gaidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at 1.ight Water Reactors,' Part 1.C of Section 3.2.1, the expected frequency of tornadoes with windspeeds greater than or equal to 113 miles per hour is to be determined using site specific data.

This value is used as a factor in an expression for calculating the

'imated frequency of loss of off-site power due to severe weather.

Nuc? ear Safety Ana., dis, using alte specific data from NUREG/CR-4461 and the National Severe Storms Forecast Center, performed three calculations regarding the annoal expected frequency of tornadoes

' intensity Icvels f2 and greater) per square mile.

The results of these calculationu have been documented in an NSA Calculation Package, Document Control No.

SR-88 001 Rev. O.

In each case, the calculation included all years for which data was provided.

The calculation values are shown in the following table Renion Egytpfq Area ( s%n}id Annual Frenuency (/m2) 125 nautical milei NSSFC 64,918.2 0.0001909 around Burlington State of Kansas NUREG 82,264 0.000226$

CR-4461 5 den, box centered NUREG 94,663.8 0.0003282 on 37.5 deg. North CR-4461 and 97.5 deg. Vest i

- - -... - _ - ~ - - _ -. -

> to ET 92-0072 Page 2 of 7 These numbers were derived from the calculation included as Attachment II.

Additionally, updated Safety Analysia Report (USAR) Section 2.3 states that the average annus1 snowfall for Wolf Creek Generating Station (WCOS) it between 10 and 20 inches, whereas Table 3.3 of NUMARC 87-00 states this value as 20 inches, t he upper limit.

Based on the most conservative of the resultant annual frequencies ( 0003282 e

per squate mile),

the following value fo-

'f' is derived from Part 1C of NUHARC 87-00.

f * (1.3 X 10) *ht + b *h2 + (1.2 X 10' ) *h3 + C *h4.

f = (1.3 X 10) (20) 4 (12.5) (.0003282) + (1.2 X 10 2) (.23) + 0.

f = 2.6 X 10~3 4 4.1 X 10'3 + 2.76 X 10'3 + 0.

f = 9.46 X 10"

~.00946 From Table 3-4 of HUMARC 87-00, this places VCGS in severe weather (SW)

Group 2.

This along with the extremely severe venther (ESW) classification of Group 1 and independence of of f site power classificati.n of Group I 1/2 results in an offsite power design characteristic of

'P1'.

WCGS will therefore remain a 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months SB0 coping duration plant with an EDG reliability target of 0.95,

2) Section 2.2.2 - Battery capacity 2.2.2 Recomunendation - The licensee should describe the load profile, method and assuniptions (e.g., teinperature correction factor, design margin, aging factor) which vere used to determine that. the battery capacity ir adequate for 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months .

If the calculation packago provides this information, the licenseu should provide the package for the staff review.

Response

4 The worst case equipment lohd profile for the Class IE butteries, as shown by USAR Tables 8.3-2 and 8.3-3, was extended from 200 minutes to 240 minutes (see following tables). This load profile is conservative for a SB0 because the increased load at 139, 199, and 239 minutes woula not be expected to occur.

The 200 minute load profile for Battery Sets 1 and 4 yields a battery demand of 737 amp-hour, which increases to 885 amp-hour for 240 minutes.

Similarly.

Battery Sets 2 and 3 have a 200 minute battery demand of 333 cmp hour, which increases to 400 amp-hout for 240 minutes.

The IEEE correction factor for 60 deg. F clectrolyte temperature is 1.11.

Also, an aging factor of 1.25 to used as the original battery design criteria used a de-rating factor of 80% of rated capacity.

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Attachment I to ET 92 0072 Page 3 of 7 TABLE 1 Battery Set 1 and 4 Load Profile (NCA-3650) f_tr_y1Lt Load / Du r a1,19,a 01 1-139 139 140 140-?.99 199-200 200-239 239-240 min min min min min min-min i

34A D-G field-flashing

34A

34A

34A 5

Class-1E ac switch.

52A l

gear C.B. Operation

52A

$2A

52A Indicating lights

]

and control circuits 67A 674 67A-67A 67A 67A 47A Instrumentation 72A 72A 72A 72A 12A 72A 72A Reactor Trip SWGR

SA

8A control

8A

8A

+-

Inverters 60A 6BA 68A 68A 68A 60A 68A control room lighting 7A 7A 7A 7A 7A 7A 7A s

D-0 Control Panel

27A SA *27A 5A

27A 5A

27A Load Shedder & Emerg.

load sequencer

84A 1A *14A

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84^

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8'A Total amperage 298 220 298 220 298 220 298 Power-(amp-min) 298 30,360 298 12,980 298 8,580 298 200 min Demand = 44,134 amp-min (737 amp-hour)

-240 min Demand = 53,112 amp-min (885 amp-hour)

-The-loads for the five operations are sequenced at different-times within-a one-ainute period and therefore cannot be considered additive loads.

The total one minute load at any instant is less than 84 amperes.

. Attachment I to ET 92-0072 Page 4 of 7 TABlX, 2 Battery S' nnd 3 Load Profile (NCX-400)

Servict Lond / Dura tion 0-1 1-139 139-140 140 199 199-200 200-240 min min min min min min Inverters 6BA 68A 68A -

60A 68A 60A Misc. indicators-32A 32A 32A 32A 32A 32A pvr. and controls.

. incl. Aux. turbine.

driven feedwater valve Total amperage

-100 100 100 100 100 100 Power (amp-min) 100 13.800 100 5,900 100 4.000 200 min Demand - 20,000 amp-min (333 amp hour) 240 min Demand - 24,000 amp min (400 amp-hour)

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Attachment I to ET 92-0072 Page 5 of 7 VCGS has four sets of Class IE batteries.

Bat'ery Sets 1 and 4 have an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months rating of 1650 amp-hours and Battery Sets 2 and 3 have an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months rating of 900 amp. hours.

The 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months battery capacities are interpolated to a 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months life, using 3 hour3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months and 5 hour5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months catalog data from Gould, yielding 1386 amp-hours for Battery Sets 1 and 4 and 756 amp-hours for Battery Sets 2 and 3.

Fattery sets 1 and 4 (Amp-flour)

]

a.

Worst case BB0 demand = 885 X 1.11 X 1.25 - 1228 amp-hour b.

1386 (capacity)/1228 (demand) = 1.128 design margin Itatt cry Set s 2 and 3 ( Amp-flour) a.

Worst case SB0 demand = 400 X 1.11 X 1.25 - 555 amp hour b.

756 (capacity)/555 (demand) = 1.362 design margin In conclusion, amplo design margins in the original sizing calculations allows. sufficient storage battery capacity to supply emergency power for an additional 40 0..sutes without shedding battery loads.

Design margins, under worst case BB0 conditions, are still 1.128 and 1.362, respectively.

These continue to conform to the original design intent of a minimum design margin of 1.1.

3) Section 2.2.3 - Air Operated Valves 2.2.3 Reccwanendation - The licensee should ensure the habitability of the arcan where valves will be manually operated during an SB0 svent.

Responso:

The safety-related air operated valves are listed in Table 9.3-2 of the USAR.

Of these safety-related valves only those controlling the steam generator atmospheric relief and those controlling the turbine-driven auxiliary feedvater pump discharge are required to remove decay heat.

The auxiliary feedwater pump steam supply valves (AB-!!V-05 and AB-HV-06) fall open on a. loss of air supply, which ensures steam supply to the auxiliary feedwater turbino.

The turbine-discharge valves. and steam generator atmospheric relief valves have a backup compressed gas supply.

The. backup compressed gas supply consists, in part, of four 25 cubic feet accumulators.

This system is a safety-related backup supply of compressed gas (USAR Section 9.3).

The system is locally and passively connected to the auxiliary feedwater discharge valves and steam generator relief valves.

If the normal air supply drops below 100 psig the accumulator valve will open providing backup compressed gas.

i Attachment I to ET 92-0072 page 6 of 7 The backup compressed gas system is designed to provide an eight hour supply of compressed gas.

The eight hour supply is based on 20 minute cycling of the auxiliary feedwater valves and 10 minute cycling of the steam generator relief valves.

The backup compressed gas system is capable of providing gas to the air operated valves needed for decay heat removal for eight hours.

This is twice the required coping duration following a station blackout event.

In conclusion, there is a safety related backup compressed gas supply system available to ensure air operated valve control for decay heat removal for the four hour coping duration, thus manual operation of the valves upon loss of the primary air supply is not necessary.

4) Section 2.2.4 - home of Ventilation 2.2.4 Reconsnendation - Yhe licensco should provide the detailed informat)on of the heat-up calculations as requested by the staff.

Rennonse:

The areas conditioned by Heating Ventilation and Air Conditioning (HVAC) units. have betn evaluated to determine the impact due to loss of ventilation.

The results of this evaluation are included as Attachment III and show that WO3S can copo 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months with a loss of IIVAC units.

An independent calculation (GK HV-004) was also performed vulch confirmed the results of this analysis for the Control Room.

The equipment cabinet doors and corridor doors to 1,e opened are included in plant operations procedure EMG C-0 ' Loss of All AC Power'.

5) Section 2.5 Quality Assurance and Technical Specifications 2.5 Recommendation - The licensen should verify that the SB0 equipment is cc,vered _by an appropriate QA program consistent with the guidance of RG 1.155.

This evaluation should be documented as part of the documentation supporting the SB0 rule / response.

Responne Upon identification of any non safety-related equipment or systems that are required to meet the requirements of 10 CFR 50.63, QA shall develop a Special. Scope QA Program to meet the requirements of Regulatory Guide 1.155 Appendix A.

Attachment I to ET 92-0072 Page 7 of 7

6) Section 2.6 - Emergency Diesel Generator (EDO) Reliability program It is the staf f's position t. hat an EDG reliability 2.6 Reconumendation program should be developed in accordance with the' guidance of RU 1.155, Section 1.2.

If the EDG reliability program currently crists, the program should be evaluated and adjusted in accordance with RG 1.155.

Coniitinat Ien that such a program is in place or will bo isopiteented should be includeo in the documentation that is to be nutintained by the licensee in support of the SB0 sutenittals.

Responses Monitoring of EDG reliability at WCGS is performed in accordance with administrative procedure ADM 01-244, ' Emergency Diesel Generator Reliability Monitoring Program".

This procedure evaluates ED3 start attempts to determine if a failure has occurred and compares failures in the last 20. 50 and 100 demands with trigger values as described in NUMAl'C 67 00, Appendix D.

Escalating corrective actions are required based on the number of trigger values reached following a failure.

This procedure meets the guidance of Regulatory Guide 1.155, Position 1.2.

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ML20094M374

Text

Reference:

Response

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