ML20245A563

Forwards Response to Station Blackout Rule (10CFR50.63). Subjs Discussed Include,Condensate Inventory of Dhr,Class 1E Battery Capacity,Compressed Air,Effects of Loss of Ventilation & Containment Isolation

ML20245A563
Person / Time
Site:	Wolf Creek
Issue date:	04/17/1989
From:	Bailey J WOLF CREEK NUCLEAR OPERATING CORP.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
NO-89-0072, NO-89-72, TAC-68628, NUDOCS 8904250271
Download: ML20245A563 (6)

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T W4#LF CREEK NUCLEAR OPERATING CORPORATION

.hhn A. Smiley woe President Nuclear Operassone .

April 17,'1989 NO 89-0072 U. S. Nuclear Regulatory Ccmnission ATIN: Document Control Desk Mal.1 Station Pl-137 Washington, D. C. 20555 T. E. Murley, Director Office of Nuclear Reactor Regulation ,

U. S. Nuclear Regulatory Cmmission Washington, D. C. 20555

Subject:

Docket No. 50-482: Response to Station Blackout Rule (NRC 'EAC No. 68628)

Gentimen: {

Attached is Wolf Creek Nuclear Operating Corporation's (NCNOC) response to the Station Blackout Rule as required by 10 CFR 50.63(c)(1). 'Ihe attachment is consistent with the generic response format provided by NLMARC.

In perfonning the Station Blackout Coping Assessment, . NCNOC utilized the NUMARC 87-00 methodology in conjunction with plant specific analyses. '1he analyses tw3uired for canplying with the Station Blackout Rule are not directly applicable to other design bases analyses. Baseline assumptions,  ;

analyses, and related information are maintained at the Wolf Creek '

Generating Station and are available'for NRC review.

l If you have any questions concerning this matter, please contact me or Mr. O. L. Maynard of my staff.

Very truly yours, d .

John A. Bailey Vice President Nuclear Operations Attactment cc: B. L. Bartlett (NRC), w/a E. J. Holler (NRC), w/a R. D. Martin (NRC), w/a D. V. Fickett (NRC), w/a

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Ro. Bm 4M / Bdington, KS 66839 / Phone: (316) 304-8831 8904250271 890427 PDR ADOCK 05000482 An Equal Opportunity Enghyer MfthCVET ,

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D Attachment to NO 89-0072 Page 1 of 5 GENERIC RESPONSE TO STATION BLACKOUT RULE FOR PLANTS USING AC INDEPENDENT STATION BLACKOUT RESPONSE POWER on July 21, 1988, the Nuclear Regulatory Commission (NRC) amended its regulations in 10 CFR, Part 50. A new section, 50.63, was added which requires that each light-water-cooled nuclear power plant be able to withstand and recover from a station blackout (SBO) of a specified duration. Utilities are expected to have the baseline assumptions, analyses and related information used in their coping evaluation available for NRC j review.

It also identifies the factors that must be considered in specifying the station blackout duration. Section 50.63 requires that, for the station blackout duration, the plant be capable of maintaining core cooling and appropriate containment integrity. Section 50.63 further requires that each licensee submit the following information:

1. A proposed station blackout duration including a justification for the selection based on the redundancy and reliability of the onsite emergency AC power sources, the expected frequency of loss of offsite power, and the probable time needed to restore offsite power;

2. A description of the procedures that will be implemented for station blackout events for the duration (as determined in 1 above) and for recovery therefrom; and

3. A list and proposed schedule for any needed modifications to equipment and associated procedures necessary for the specified SB0 duration.

The NRC has issued Regulatory Guide 1.155 " Station Blackout" which describes a means acceptable to the NRC Staff for meeting the requirements of 10 CFR 50.63. Regulatory Guide (RG) 1.155 states that the NEC Staff has determined that NUMARC 87-00 ' Guidelines and Technical Bases for NUMARC Initiatives '

Addressing Station Blackout At Light Water Reactors" also provides guidance that is in large part identical to the RG 1.155 guidance and is acceptable to the NRC Staff for meeting these requirements.

Table 1 to RG 1.155 provides a cross-reference between RG 1.155 and NUMARC 87-00 and notes where the RG takes precedence.

Wolf Creek Nuclear Operating Corporation (WCNOC) has evaluated the Wolf Creek Generating Station (WCGS) against the requirements of the SB0 rule using guidance from NUMARC 87-00 except where RG 1.155 takes precedence.

The results of this evaluation are detailed below. (Applicable NUMARC 87-00 sections are shown in parentheses.)  ;

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. Attachment to NO 89-0072 Page 2 of- 5 1

A. Proposed Station Blackout Duration i

NUMARC .87-00, Section 3 was used to determine a proposed SB0 duration of i four hours. No modifications were required to attain this proposed coping l duration category.

The following plant factors were identified in determining the proposed station blackout duration:

1. AC Power Design Characteristic Group is P1 based ons

a. Expected frequency of grid-related LOOPS - does not exceed once per 20 years (Section 3.2.1, Part 1A, p. 3-3):

b. Estimated frequency of LOOPS due to extremely severe weather places the plant in ESW Group 1 (Section 3.2.1 Part 1B, p. 3-4);

c. Estimated frequency of LOOPS due to severe weather places the plant in SW Group 2 (Section 3.2.1, Part 1C, p. 3-7). WCNOC performed a calculation of the annual expectation of tornadoes of severity f2 or greater in events per square mile using NUREG/CR-4461, " Tornado Climatology of the Contiguous United States" and site specific data provided by the National Severe Storms Forecast Center with a resultant value of 0.0003282:

d. The offsite power system is in the.II/2 Group (Section 3.2.1, Part 1D, p. 3-10):

2. The emergency AC power configuration group is C based on: (Section 3.2.2, Part 2C, p. 3-13)

a. There are 2 emergency AC power supplies not credited as alternate AC power sources (Section 3.2.2. Part 2A, p. 3-15):

b. One emergency AC power supply is necessary to operate safe i shutdown equipment following a loss of offsite power (Section 3.2.2, Part 2B, p. 3-15).

3. The target EDG reliability is 0.95.

a. A target EDG reliability of 0.95 was selected based on having a nuclear unit average EDG reliability for the last 100 demands greater than 0.95 consistent with NUMARC 87-00, Section 3.2.4.

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1 Attachment to NO 89-0072

-Page= 3 of 5 B; Procedure Description Plant' procedures have been reviewed and modified, if necessary.. to meet the-guidelines in NUMARC 87-00 Section 4 in the following areas.

1. 'AC power restoration per NUMARC 87-00, Section 4.2.2; System procedures' adequately address AC power restoration.

2. Severe weather per NUMARC 87-00, Section 4.2.3.

OFN 00-003, Natural Events.

'C. Proposed Modifications and Schedule No modifications proposed.

REQUIRED SB0 DURATION:

The ability of Wolf Creek Generating Station.to cope with a station blackout for four (4) hours in accordance with NUMARC 87-00, Section 3.2.5 and as determined in'Section "A" above; was assessed using NUMARC 87-00, Section 7 with the following rasults:

1. Condensate Inventory For Decay Heat Removal (Section 7.2.1)

It hr.s geen determined from Section 7.2.1 of NUMARC 87-00 that 1.51 X 10 gallons of water are required for decay heat removal.for four (4) hours. The minimum permissible condensatg storage tank' level per technical specifications provides 2.81 X 10 gallons of water, which exceeds the required quantity for coping with a four-hour station blackout.

No plant modifications or procedure changes are needed to utilize these water sources.

2. Class 1E Batteries Cacacity (Section 7.2.2)

A battery capacity calculation has been performed pursuant to NUMARC 87-00, Section 7.2.2 to verify that the Class 1E batteries has sufficient capacity to meet station blackout loads for four hours.

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4 1 Attachment to NO 89-0072 3 Page 4 of .5.

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3.- Compressed Air (Section 7.2.3)

Air-operated valves relied upon to cope with a station blackout for

'four. hours can either be operated manually or have sufficient backup sources independent of'the preferred and blacked out unit's Class 1E power' supply. . Valves requiring manual operation or that need; backup sources for operation are identified in plant

' procedures.

4. Effects of Loss of Ventilation (Section 7.2.4)

a. The calculated steady state ambient air _ temperature for the steam driven AFW pump room (the dominant area of concern for a PWRf during a station blackout induced loss of ventilation is 150 F.

b. Control Room Complex TheassumptioninNUMARC8f-00, Section 2.7.1 that the control room will not exceed 120 F during a station blackout has been assessed.

ThecontrogroomatWolf Creek Generating Station does not i exceed 120 F during a station blackout. Therefore, the control room is not a dominant area of concern.

Reasonable assurance of the. operability of station blackout response equipment in the'above dominant area (s) has been assessed ,

using Appendix F to NUMARC 87-00. The following modifications and/or associated procedure changes are required to provide i reasonable assurance for equipment operability:  ;

1. Open all corridor doors adjacent to the turbine-driven j auxiliary feedwater pump room.

2. Open designated instrument, control and protection cabinets in the control building cabinet area.

5. Containment Isolation (Section 7.2.5)

The plant list of containment isolation valves has been reviewed to verify that velves which must be capable of being closed or that must be operated (cycled) under station blackout conditions can be positioned (with indication) independent of the preferred and blacked-out unit's Class .1E power supplies. The following modifications and/or associated procedure changes are required to ensure that appropriate containment integrity can be provided under station blackout conditions:

a. Prioritization of the closure sequence of containment isolation valves.

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e h Attachment to NO 89'-0072 Page 5 of~ 5 .

6. Reactor Coolant Inventory (Section 2.5)

The ability to maintain adequate reactor, coolant system inventory to ensure that the core is cooled has been assessed for- 1 four hours. .The generic analyses listed in Section 2.5.2 of NUHARC 87-00 were used for this assessment and are applicable to the specific design of the Wolf Creek Generating Station. .The expected rates of reactor coolant inventory loss under SB0 conditions do not result in core uncovery in a SB0 of four hours. . Therefore, makeup.

systems in' addition to those currently. available under SB0 conditions are not required to maintain core cooling under natural circulation (including reflux boiling).

No modifications or procedure changes are identified in Parts A, B and C above. The procedure changes identified in required SB0 duration assessment will be completed 6 months after the notification provided by the. Director, Office 'of Nuclear Reactor Regulation in accordance with 10 CFR 50.63(c)(3).

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