ML20086N300

Final Technical Evaluation Rept,Catawba Nuclear Station, Station Blackout Evaluation

ML20086N300
Person / Time
Site:	Catawba
Issue date:	12/10/1991
From:	SCIENCE APPLICATIONS INTERNATIONAL CORP. (FORMERLY
To:	NRC
Shared Package
ML20086N303	List: ML20086N300
References
CON-NRC-03-87-029, CON-NRC-3-87-29 SAIC-91-1267, TAC-M68527, TAC-M68528, NUDOCS 9112190261
Download: ML20086N300 (33)

Text

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Attach w SAIC 91/1267 l

TECl{NICAL EVALUATION REPORT CATAWilA NUCLEAR STATION STATION 13LACKOUT EVALUATION TAC Nos. 68327 and 68528

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Science App'ications k1temationalCorporution An Empicyee-Owed Company Final December 10,1991 Prepared for:

U.S. Nuclear Regulatory Commission Washington, D.C. 20$55 Contract NRC 03 87 029 -

Task Order No. 38 1710 Gooandge Drove. PO Bos I303. McLeon. Wginna 22102 1703I 8:1 4300

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'4 e TABLE OF CONTENTS Section hgg 1.0 B A C K G R O U N D .. . ... . .. . . . . . . .. . . . .. . . . . . . .. .. .. . .. ... . ... ... ... .I .. ...... . ... . . .

2.0 R E V 1 E W P R O C E S S . . . . . ... ....... . . .... . ..... . .. . .. .......... .. ...... .. ... 3 .....

3.0 E VAL U NTl O N . . . . . . .. . . . . .. . .. . . . . .. . . . . . .. . . . . . . . . . . . . . . . .. . . . 6. . . . . . . . . . . . . . . . . .

3.1 Proposed Stt. tion Blackout Duration ........ ............ 6 3.2 Alternate AC ( AAC) Power Source...................... 10 3.3 Station Blackout Coping Capability ....................... 11 3.4 Proposed Procedures and Training ............... ... .... 25 3.5 Propos e d Modifications ............................ .... ........... 25 t

3.6 - Quality Assurance and Technical Specifications . 26 4.0 CO N C L U S t O N S .. . . . .. . ... . . . .... . . . .. .. . . ... . .. . . . ... ..... . ....... . . .27 .... . . . . . ... .

s 5.0 R E F E R E N C E S . . . . . . . . . . . . . .. . .. . . . . . . . . . . . . . . . . .. . . . . . .. .. . ...29 ... .. . . . . . . . . . . . . . . .

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TElliNICAL EVALUATION REPORT CATAWilA NUCLEAR

• TAT!9N STATION BLACKOLT EVALUATION 1.0 HACKGROUND On July 21,1988, the Nuclear Regulatory Commission (NRC) amended its regulations in 10 CFR Part 50 by adding a new section 50.63 ' Loss of All Alternating Current Power" (1). Tha objective of this requirement is to assure that all nuclear power plants are capabie of withstanding a station blackout (SBO) and maintaining adequate reactor core cooling and appropriate containment integrity for a required duration. This requirement is based o;t information developed under the commission studyof *Jnresolved SafetyIssue A 44 " Station Blackout"(2 6).

The staff issued Regulatory Guide (RO) 1.155," Station Blackout," to provide guidance for meeting the requirements of 10 CFR 50.63 (7). Concurrent with the development of this regtdatory guide, the Nuclear Utility Management and Resource Council (NUMARC) developed a document entitled," Guidelines and Technical Basis for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors." NUMARC 87 00(S). This document provides detailed guidelines and procedures on how to assess each plant's capabilities to comply with the SBO rule. The NRC staff reviewed the guidelines and analysis methocoiugy in NUMARC 87 00 and concluded that the NUMARC document provides an acceptable guidance for addressinE the 10 CFR 30.63 requirements. The application of this method results in selectmg a minimum acceptable SBO duration capability from two to

- sixteen hours depending on the plant's characteristics and vulnerabilities to the risk from station blackout. The plant's characteristics affecting the required coping capability are:

the redundancy of the onsite emergency AC power Sources, the reliability of .onsite emergency power sources, the frequency of loss of offsite power (LOOP), and the probable time to restore offsite power.

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in order to achieve a consistent s sty ematic response fro. :lcensees to the 500 rule and to expedite the staff review process. NUMARC developed two generic response documents.

These documents were reviewed and endorsed (9) by the NRC staff for the purposes of plant specific submittals. The documents are titled:

1. " Generic Response to Station Blackout Rule for Plants Using Ahernate AC Power" -

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• Generic Response to Station Blackout Rule for Plants U ins g AC Independent Station Blackout Response Power."

A plant specific submittal, usirg one of the above generic formats, provides only a summary of results of the analysis of the plant's station blackout coping capability.

Licensees are expected to ensure that the baseline assumptions used in NUMARC 87 00 are  ;

apficable to their plants and to verify the accuracy of the stated results. Compliance with the SBO rule requirements is verified by review asid evaluation of the licensee's submittal and audit review of the supporting documents as necessary. Follow up NRC inspections _

-assure that the licensee has implemented the necessary changes as required to meet the SBO rule. '

In 1989, a joint NRC/SAIC team headed by an NRC staff member perforrned audit reviews of *he-methodology and documentation that support the licensees'subi tals for several plants. These audits revealed several deficien:les which were not apparent f rom the review of the licensees'suomittals using the agreed upon generic response formst These $

deficiencies raised a generic question regarding the degree of licensees' conformanct to the i

. requirernents of the SBO rule; To retolve this question, on Jant ny.4,1990, NUMARC issued additional guidance as NUMARC 87 00 Supplemental-Questions / Answers (10) addressing the NRC's concerns regarding the deficiencies. NUMARC requested that the ,

licensees send their Fupplemental responses to the NRC addressing thet e concerns by March a 30,~ 1990.

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2.0 REVIEW PROCESS i

The review of the licensee's sut.aittalis focused on the following areas consistent with the positions of RG 1.155:

A. Minimum acceptable SBO duration (Section 3.1),

B. SBO coping capab!!ity (Section 3.2),

C. Procedures and trainin; for SBO (Section 3.4),

D. Proposed niodifications (Section 3.3), and E. Quality assurance and technical specifications for SBO equipment (Section 3.5).

For the determination of the proposed minimum acceptable SBO duratien. the following factors in the licensee's rubmittal-are reviewed: a) offsite power design characteristics, b) emergency AC power system configuration, c) determination of the emergency diesel generator (EDG) relie' "try consistent with NSAC-108 criteria (11), and d) determination of the accepted EDG to ~iability. Once these factors are known, Table 3 8 of NUMARC 87 00 or Table & at RG 1.155 provides a matrix for determining the required coping duration.

L For the SBO coping capability, the licensee's submittal is reviewed to assess the availability. adequacy and capability c' .he plant systems and components needed to achieve and maintain a safe shutdown condition and recover from an SBO cf acceptable duration which is determined above. The review process follows the guidelines given in RG 1.155.

.Section 3.2, to assure:

, a. availability of sufficient condensate inventory for decay heat removal, 3

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b. adequacy of the' class lE battery capacity to support safe shutdown,

c. availability of adequate compressed air for air operated valves necessary for safe shutdown,

d. adequacy of the ventilation systems in the vital and/or cominan; areas that include equipment necessary for safe shutdown of the plant, e, ability to provide appropriate containment integrity, and i

f. ability of the plant to maintain adequate reactor coolant system inventory to ensure Lcore cooling for the required coping duration.

j The licensee's submittal is reviewed tn verify that required procedures (i.e., revised existing and new) for coping with SBO are identified and that appropriate operator training w.'ll be provided.

q The licensee's submittal for any proposed modifications to emergency AC sources, battery capacity, condensate capacity, compressed air capacity, ventilation systems, ,

contairiment isolation integrity, and primary coolant. make up capability is reviewed.  ;

Technical specifications and quality assurance set forth by the licensee to ensure high reliability of the equipment, specifically added or assigned to meet the requirements of the SBO rule, are assesse.d for their adequacy.

The licensee's proposed use of an alternate AC power sot.rce is reviewed to determine .;

- whether it meets the criteria and guidelines of Section 3.3.5 of RG 1.155 and Appendix B of NUMARC 87-00, i

'This SBO evaluation is based upon the review of the licensee's submittals dated April 17, 1989 (12), and April 4, 1990 (13), the information available in the plant Final Safety I L

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Analysis Report (FSAR) (14), a meeting with the licensee in Charlotte, North Carolina. and

.the information provided by the licensee following the meeting (15),

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. 1 3.0 EVALL'ATION 3.1 Proposed Station Blackout Duration Licensee's Submittal The licensee. Duke Power Company, calculated (12 and 13) a minimum acceptable station blackout duration of four hours for the Catawba Nuclear Station (CNS) site.

The licensee stated (13) that no equipment modifications are required to attain this coping duration.

The plant factors used to estimate the proposed SBO duration are:

1. Offsite Power Design Characteristics The plant AC power design characteristic group is "P1" based on:

a. Independence of the plant offsite power system characteristics of "II/2,"

b. Expected frequency of grid related LOOPS ofless than one per 20 years,

c. Estimated trequency of LOOPS due to extremely severe weather (ESW) which places the plant in ESW Group "1." and

- d. Estimated t'requency of LOOPS due to severe weather (SW) which places the plant in SW Group "1."

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2. Emergen,:y AC (EAC) Power Configuration Group The EAC power configuration of the plant is "C/' Each unit is equipped with two dedicated emergency diesel generators (EDGs). One EDG per unit is necessary to operate safe shu.down equipment following a loss of offsite power.

3. Target Emergency Diesel Generator (EDG) Reliability The licensee has selected a target EDG reliability of 0.95. The selection or. his target reliability is based on having an average EDG reliability of greater than 0.95 for the last 100 demands, consistent with NUMARC 87 00, Section 3.2.4 The licensee stated that the actual unit averages over the last 100 demands were 0.955 for Unit I and 0.985 for Unit 2, based on late 1988 data.

Resiew of Licensee's Submittal Factors which affect the estimation of the SBO coping duration are: the independence of the offsite power system gnuping, the estimated frequency of LOOPS due to ESW and SW conditions, the expected frequency of grid related LOOPS, the classification of EAC, and the selection of EDG target reliability. The licensee stated that the independence of the plant offsite power system grouping is "Il/2." A review of the avuitable information shows that:

l_. There is one switchyard for the site;

2. During normal operation, power is provided to the safety busses from the main generator;

3. Upon main generator trip, the generator breakers automatically open and offsite power is povided from two step-up transformers (SUTs), one for each divisior.:

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4. Each SUT supplies power to two unit atailiary transformers (UATs), w hich, in turn.

_ provide power to a split bus arrangement:

5. The split busses provide power to the safety related busses;

6. Upon loss of power to the portion of a split bus which provides power to the safety-related busses, the appropriate split bus tie breaker automatically closes to power the safety loads.

Based on these and the criteria stated in Table 5 of RG 1.155, the plant independence

- of offsite power system group is "12."

With regard to the expected frequency of grid related LOOPS at the site, we can not confirm the stated results. The available information in NUREG/CR 3992 (3), which gives a compendium of information on the loss of offsite power at nuclear power plants in the U.S., only covers these incidents through the calendar year 1984 Catawba Nuclear Station Units 1 and 2 did not enter commercial operation until 1985 and 1986, respectively. In the absence of any contradictory information, we agree with the licensee's statement,

-Using Table 3-3 of NUMARC 87 00, the expected fregt;;ncy of LOOPS at Catawba due to SW condition is Group "2." Using Table 3 2 of NUMARC 87 00, the expected frequency of LOOPS due to ESW conditions place the Catawba site in ESW Group "3."

The licensee used site specific data (13) to determine ths the site is in SW Group "1" and ESW Group "1." The ESW grouping makes a difference in the offsite power design-characteristic group; NUMARC data places _the site in the P2" category whereas the L McGuire ESW data liaces the site in the "P1" category. We spoke to the NRC staff who provided NUMARC with the weather data. Since both Catawba and McGuire are

!' :within 35 miles of Charlotte, NC, Charlotte weather data can be used for both sites.

The Charlotte weather data was used for the McGuire ESW Group "1." Therefore L '8 n

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- Catawba and McGuire should have the same ESW grouping of "1." The offsite power design characteristic is not affected by the licensee's use of site specific data for the SW

. grouping; the offsite power design characteristic is "P1" regardless of whether the SW Group is "1" or "2."-

The. licensee correctly categorized the EAC classification of CNS as "C." Each unit has two dedicated 7000 kW EDGs, one of which is necessary to safely shut down the reactor.

.The licensee selected an EDG target reliability of 0.95 based upon the EDG reliability data for the last 100 demands. Although this is an acceptable criterion for the selection of an EDG target reliability, the licensee needs to have statistics for the last 20 and 50

1. demands % its SBO submittal supporting documentation. The information in NSAC 108 (11) gives we.ED_G reliability' data at U.S. nuclear reactors for calendar years 1983 to - g 1985. . Catawba Units 1 and 2 did not enter cor.unercial operation until 1985 and 1986, respect.vely.- Consequently, NSAC.108 does not contain any information on the reliability of EDGs at Catawba. However, the licensee can choose any EDG target reliability consistent with the minimum required SBO coping duration, provided that it

?is maintained. The licensee has provided this commitment in its submittal dated April 4, 1990 (13).

With regard to maintaining the 0.95 EDG reliability target value, the licensee stated (15) that it currently has in place programs which are designed to maintain the reliability of Et he EAC powerjsources. These programs include among other things maintenance, Ltesting, surveillance, and root cause investigation. In addition, the ilemsee stated that fit is closely following the progress of Generic Issur B-56 and, upon the resolution of this' generic isstie, the licensee will review its emergency cower source reliability programs

~ and.make changes ~as necessary.- '

Based on the above, the offsite power design characteristic of the Catawba site is "P1,"

with a minimum required SBO coping duration of four hours.

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i a 3.2 Alternate AC (AAC) Power Source Licensee's Submittal The licensee stated (13) that an AAC power source is provided at Catawba which meets the criteria specified in NUMARC 87 00, Appendix B. The AAC power source is the Standby Shutdown Facility (SSF) diesel generator which is the power source for the Standby Shutdown System (SSS). The SSF diesel generator is available within 10 minutes from the recognition of an SBO event. However,it cannot be started from the Catawba main control room. The licensee stated that testing has demonstrated the ability of plant operators to start the SSF diesel within 10 minutes of the recognition of the SBO event which satisfies the intent of the NUMARC guidance. The licensee added that the SSF diesel generator has sufficient capacity and capability to operate equipment necessary to maintain safe shutdown condition for the four hour SBO event.

In addition, the SSF was originally designed to provide an alternate means of achieving and maintaining hot standby conditions following a postulated fire or sabotage event.

Loss of all normal and emergency station power (AC and DC) is assumed for the postulated fire and sabotage events. Because of this, the licensee concluded that the SSF diesel genuator and the SSF are also designed to handle the SBO event. The licensee added that the NRC has previously reviewed and approved the SSF design as noted in the Catawba SER Supplement 4, dated December 1984.

Review of Licensee's Submittal The licensee's proposed AAC power source, the 700-kW SSF diesel generator, is designed to meet the requirements of Appendix R. The SSF contains its own control room, diesel generator, AC and DC distribution system, HVAC system, and lighting system. The SSF _ diesel generator powers one make-up pump per unit which is located inside containment. In order to provide water to the steam generators. the normal unit 10

I turbine driven AFW pump is required. The controls for the pump are independent of the normal plant controls.

The SSF has been approved for Appendix R by the NRC to be capable of maintaining both units in hot standby for a period of up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and, with the exception of the AFW pump, is completely independent of the normal plant systems. Since the SSF diesel generator meets the criteria of NUMARC 87 00. Appendix B. we consider it to be an AAC power source.

3.3 Station Blackout Coping Capability The licensee's position is that in the most probable scenario, it will use a combination of normal plant systems and certain SSF capability to achieve and maintain hot standby conditions from the main control room. Therefore, our evaluation of Catawba Nuclear Station consists of two parts: the plant's ability to cope with an SBO event with normal plant systems and with a combination of the normal plant systems and those available from the SSF.

The plant coping capability with an SBO event for the required duration of four hours is assessed with the following results:

1. Condensate Inventon for Decay lient Removal Licensee's Submittal The licensee stated that from Section 7.2.1 of NUMARC 87-00, it has determined that 75,452 gallons of water are required for decay-heat removal during the four-hour coping period.

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f Plant SysJims The 1,'censee stated (13) that the turbine driven auxiliary feedwater pumps would be aligned to the following normal sources of condensate grade water:

1. Auxiliary feedwater condensate storage tank 45,000 gallons (This tank is shared between units) 2, Upper Surge Tanks 85,000 gallons

3. Condenser Hotwell - 170,000 gallons Based on these sources being available, the licensee concluded (13) that there is sufticient water available to cope with a four hour SBO event.

SSF Feature The licensee stated that, in addition to the normal condensate sources listed above, the SSF also has the ability to align to the Condenser Circulating Water System (CCWS), which has the capability to maintain hot standby conditions for anproximately 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The licensee added that no plant modifications or procedure changes are necessary to use these water sources, o

Review of Licensee's Submittal Using the expression provided in NUMARC 87 00, we have estimated that the water required for removing decay heat during the four hour SBO would be ~77,000 gallons. This estimate is based on 1029c' of a maximum licensed core thermal rating of 3411 MWt. During the audit review in Charlotte, NC, the licensee stated that it has no plans to cool down the primary system during an SBO event. If, however, the pump seal leakage is such that it requires cooldown (see Reactor Coolant Inst.ntory section), then the licensee will follow Westinghouse procedure ECA 0.0. Based on the analyses from similarly sized Westinghouse plants which plan to cool down, we estimate that ~90,000 gallons of water will be necessary to depressurize the primary 12

system to a secondarf side pressure of 250 psig. With cooldown, th total amount of wat". ;cessary is -170,000.

During the audit review, the licensee provided information on the Catawba condensate storage system. Unit 2 has a technical specifications which requires a minimum of 225,000 gallons in the combmation of the condenser hotwell, the condensate storage tank, and the upper surge tank. For Unit 1 the licensee also provided a statement which indicates that the minimum available volume of water in the condenser hotwell is 82,500 gallons. If the water drops to this level, there is a low level alarm and the operators are instructed by procedure (alarm response manual) to refill the hotwell, Similarly, there is a low level alarm when the upper

t. urge tank volume reaches 42,500 gallons, c response to which the operators are instructed to refill the tank, The licensee also stated ; hat the auxiliary feedwater storage tank is continuously being refilled and overflowing, and therefore should have 45,000 gallons for both units (22,500 gallons per unit). The total of these three volumes is 147,500 gallons. There are, however, no technical specifications limits on the levels of these water sources for Unit 1, and therefore there are no guarantees that these sources of condensate will be available during an SBO event. If, for any reason, sufficient sources of condensate grade water are unavailable, the licensee can ,

align the turbine-driven AFW pump to take suction from the CCWS, which can provide non condensate grade water for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Therefore, Catawba has sufficient sources of water to cope with a four hour SBO event.

2. Class 1E Battery Capacity +

Licensee's Submittal Plant Svstem The licensee stated (13) that a plant specific battery-capacity calculation verifies that

, the class-1E batteries in each unit are sized to carry that unit's required SBO load 13

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without load stripping for four hours. The vital I & C batteries are not capable of ,

being charged from the AAC souice (SSF diesel generator). However, the battery capacity meets the required SBO coping duration.

SSF Feature The licensee stated that the SSF is also provided with a 250/125 VDC power system which is independent from the normal plar' 125-VDC and 120 VAC vital I&C power system. The SSF batteries are charged by the AAC power source and are also available to power the SSF instruments and controls necessary to achieve and maintain hot standby conditions from the SSF control room following an SBO event.

Review of I.lcensee's Submittal i

Upon review of the plant FSAR, we found that the class-lE batteries can support the design loads for two hours. The licensee stated that the batteries are capable of carrying the SBO loads for four hours without load shedding. Following the site audit review, the licensee provided its battery-capacity calculation. In the calculation, the licensee assumed an aging factor of 1.25, a temperature factor of 1.11 ; corresponding to 60*F), a design margin of 1.10, and a load growth factor of ,

1.05. At the end of four hours, the excess margin was 9Fe. Our review of the calculation produced the following concerns:

1.- The battery loads assumed by the licensee are based upon the loads measured

during a blackout test, not upon the rated loads of the equipment. In order to ensure that these loads are representative of the expected loads during an SBO,-

the licensee needs to repeat the blackout test periodically and update its battery. "

L capacity calculation as needed, or provide other assurance that the loads that- ,

could occur during an SBO event would not exceed those measured during the test.

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2.- In the calculation, thre is no-last minute load increase. This load increase represents either field flashing for the EDGs or closing the necessary circuit breakers to restore offsite power, whichever is more limiting. Since the EDGs at Catawbs have their own batteries, the limiting case is the closing of circuit breakers.

According to the plant FSAR, the EDO batteries are designed to last for two hours.

The licensee needs to ensure that these batteries will have sufficient capacity for the EDG field flashing at the end of the SBO event.

The SSF has it< own independent battery system which will be charged by a-battery charger powered by the AAC power source.

3. Compressed Air

. Licensee's Submittal '

Plant System '

The licensee stated (13) that no air operated valves are relied upon to cope with a

- four-hour SBO event. However, in an SBO event, air can be supplied from a diesel-drivel air compressor and/or un instrument air system compressor powered from the -

non-blacked out (NBO) unit. The licensee stated that this back up air capability provides the operators flexibility in being able to maintain hot standby conditions from the main control room. The licensee added that these air cperated valves can be manually positioned and are identified in plant procedures.

ESF Feature The licensee stated (13) that no air operated valves are relied upon to maintain hot f standby conditions from the SSF.

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Review of Licensee's Submittal Our review of FSAR Section 9.3.1.2.1 indicates that Catawba has a portable diesel-driven air compressor which can be used in the event of the loss of the normal plant air compassors. During the site audit review in Charlotte, the licensee stated that it do not want to place the diesel driven air compressor on its quality assurance (QA) list. As a result of this, our analysis does not consider compressed air tc be available. Section 10.3.2 of the plant FSAR indicates that the power operated relief valves (PORVs) can be actuated by either a pneumatic piston operator or local handwheel. The licensee can manually operate the PORVs, which are controlled from the outboard doghouse, and operators in the doghouse can communicate with the control room operators via pertable radio communications. The habitability of the outboard doghouse will be discussed in the Loss of Ventilation section of this review.

In addition to the PORVs, the AFW flow controlvalves are also air operated under normal conditions. However, during an SBO, these valves, in combination with normally locked open, manually operated gate valves, will need to be manually operated in order to control the steam-generator water level. The AFW flow control valves and the gate valves are located in the AFW pump room. Communications between the operators _ performing the. manual actions and the control room operators will be accomplished via portable radio communications. The accessibility-

of the valves and the habitability in the AFW pump room will be discussed in the

Loss of Ventilation section.

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4. Effects of Loss of Ventilallon Licenset's Submittal Plant System The licensee provided the results of its heat up calculations in the dominant areas of concern (DACs) as follows:

DAC Tempfstture ('F)

Jnillal Emal Containment 120 205 Annulus 126 180 AFW Pump Room t 135 Turbine Driven AFW Pump Pit t 160 Mechanical Penetration Rooms t 188 Inboard Doghouses 151 t . Cakulation performed using a sicady start heat balance betett 6 the area afd the surrownding areas initial temperaturcs wers assumeJ fot the wrrounding areas, not for the area for which the cakulation was oeing performed.

-$ Neither a calculation nor alt initial left,perAture prtmded b) the beenset The licensee stated (13) that plant specific calculations and assumptions were used to determine the DAC temperatures. The licensee added that reasonable assurance of the operability of SBO response equipment in the above DACs has been addressed using NUMARC 87-00, Appendix F and/or the Topical Report. The licensee added that no modifications or procedure changes are required to provide reasonable assurance of equipment operahility.

e . Control Room.

The licensee stated (13) that the main control room is shared between the units, and is served by a shared heating, ventilation, and air conditioning (HVAC) system. The HVAC system, which will- be powered from the NBO unit's available EDG, will be available approximately 45 minutes after the onset of an SBO event. The licensee stated (13) that the control room temperature will be maintained at approximately 75'E with a possible short duration excursion above 17

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75*F (but not exceeding 120 Fi tor the period required to re align the HVAC to the operable EDO. The licensee concluded that the control room is not a DAC.

• Switchgear Room The licensee stated (13) that the train "A" Unit 1 and 2 essential switchgear rooms will not exceed 120 F during an SBO event and, therefore are not DACs.

• Turbine Building The licensee stated (13) that the turbine building is not a DAC as there would not be a significant change in the turbine building emironment as a result of an SBO event.

SSF Feature The licensee stated (13) that the SSF has its own ventilation system which is powered from the SSF diesel generator and, therefore, the SSF is not a DAC. Areas other than the SSF that contain SBO response equipment that is used in conjunction with the SSF are addressed above, Review of Licensee's Submittal The licensee provided (15) its calculations for the turbine driven AFW pump room, the containment and annulus. The steady-state calculations were based upon a heat

@ balance between the area of concern and its surrounding rooms. The assumptions used by the licensee seemc<' reasonable. No calculation was provided for the doghouse nor the mechanical penetration room.

Based upon the information provided by the licensee following the audit review in Charlotte, we agree with the licensee's conclusions for the annulus, the inboard doghouse, and the turbine building. With regard to the remaining areas, we have the following comments:

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Containment The licensee provided (15) two heat up calculations for the containment following a loss of all AC power. One of these calculations used a hand calculated time-dependent hat transfer method. This calculation did not include the postulated 111 gpm ieak rate (25 gpm per reactor coolant pump and 11 gpm technical specifications) nor the ice inside cr ntainment, A leak rate of 6700 lbm/hr was assumed, which corresponds to a leak rate of ~18 gpm. This calculation resulted -

in a final temperature of 205'F, assuming an initial temperature of 120 F. The second calculation was performed using the MAAP computer code and assumed an initial leak rate of 111 gpm. This calculation resulted in a final temperature of

~170 F and a peak temperature of ~196'F with an assumed initial terr.perature of 120'F. Both the final temperature and the peak temperature are below the temperature for which the licensee evaluated the SBO equipment oper Ability 3 (205'F). Therefore, we concur with the licensee's conclusion concerning the equipment operability inside containment.

AFW Pump _ Room ansLPli The licensee provided two separate calculations for these two areas. The turbine-driven AFW pump pit is located in a corner of the AFW pump room, and the two areas have direct communication.' The calculation for the pump pit which produced a final temperature of 160*F is reasonable and, therefore, we concur-with the lic:nsee's conclusion for this area. The cam 11ation for the AFW pump room was pe rformed assuming the conditions expected during SSF operation. This calculation, however, included a ventilation fan. The licensee needs to verify that this fan is DC-powered and will be available during an SBO event. The AFW pump room also houses the handwheels which will need to be operated in crder to control the steam-

[ generator water level. The temperature in the room (135'F) should not preclude the operators from performing the necessary manual actions. During the site audit review, we saw the AFW pump room at Catawba. While in this room, we noticed that access to the handwheels for the AFW flow control valves is teasible but l

19 l

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. difficult. This is due to the 10 cation of the control valve handwheels wh;ch is about

seven feet above the floor and in a cramped area. The licensee stated that it will

~

use a :ombination of a normally locked open gate valve and flow control vahes to adjust the flow 'to each steam generator. In addition, laddera, wnich have been preWnly identified as required support equipment for the operation of the flow control valves under Appendix R, are available in the area near the valves.

Communicationwith the controbroom personnelis accomplished via portable radios.

The operator actiont necessary to manually control it'e steam generator water level during an SBO event are consistent with those which have been addressed under Appendix R.

Mechanical Penetration Room We did not receive a calculation for the Catawba mechanical penetration room. We did, however, receive a calculation for the McGuire mechanical penetration room which produced the sarie final calculated temperature (188*F). The licensec needs to verify that this calculation is applicable to Catawba.

_Qutboard Doghouses As mentioned in the- Compressed Air section, operators may need to perform manual PORV actions in the outboard doghouse during an SBO event. The outboard doghouse is open to the outside air on three sides and has no forced ventilation; it relies on natural circulation to provide the necessary cooling. Under SBO conditions, the heat load in the outboard doghouse could be larger than under

- normal operating conditions. The additional heat loau is due to the safety-valve tail pipes. However, this additional heat load should not affect the operators' ability to manually control the PORVs due to the doghouse *3 three open sides. Therefore, we concur with the licensee's conclusion regarding the outboard doghouse.

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_ Control f<oom

. The Catawba control room is shared between the two units. The control area HVAC system consists of two redundant systems with one system capable of being powered from each unit. Each system prosides heating and air conditioning to the control room. switchgear room, battery room, mechanical equipment room, motor control center rooms, cable room, and electrical penetration room. Each room >

within the control area has its own ventilation system consisting of two 1000-capacity fans, Each of the control area heating and cooling systems is connectable

- to either of its respective unit's two emergency busses. There is a selector switch which prevents the system from being powered from both emergency busses at once.

Normally, power for the system comes from one of the emergency busses. Since the NBO unit will Hvc one EDG available, there is a 50% chance that one HVAC '

t system will be available in a short period of time after the onset of an SBO event.

Should the NBO's HVAC system be aligned to the emergency bus with the failed EDO, manual actions will be required to re align the HVAC system to the powered bus. The rnanual actions would take no more than 45 minutes. We consider the venti!ation fans for each of the rooms within the control area are designed such that they are capable of being powered from any of the emergency busses. The licensee needs to verify that this is the case. For its assessment of the control room heat up,

the licensee assurned that the room temperature at the onset of the SBO event is

-757. The licensee's use of this initial temperature is non conservative. However, since HVAC will be available to the control room within 45 minutes of the caset of an SBO event, we agree with the licensee that the control-room temperature will not exceed 120T during an SBO event. Nevertheless, the licensee . Jds to'open the control room cabinet doors within 30 minutes in the absence of air conditioning, consistent with the guidance.

Switchcear Room During the site ' audit review in Charlotte, the licensee stated that the sonchgear room will have HVAC available within 45 minutes of the onset of an SBO event.

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The switdtgear room ternperature, therefore,is not expected to e4ceed 120'F during l

the first hour of an SBO event. Bned upon the licensee's statement, we concur that the switchgear room should not ce a dominant area of cor.cern. Since the availability of HVAC to the switchgear room nas not been formally documented, the licensee needs to verify that the switchgear room will have llVAC available within 45 minutes.

5. Containment isolation Licensee's Submittal flant System T', licensee stated that the plant list of containmem isolation valves (CIVs) has been reviewed to verify that valves which must be capable of being closed or that must be operated (cycled) under SBO conditions can be positioned with indication independent of the blacked out unit's class lE power supplies. The licensee added that no modifications or associated procedure changes were determined to be cequired to ensure that appropriate containment integrity can be provided under SBO conditions.

SSF Feuurt Same as above.

Review of Licensee': Submittal During the site audit review, the licensee stated that it used the plant list of CIVs and excluded valves based on the criteria given in RG 1.155. Closure confirmation for the valves which were not excluded by the criteria have been incorporated in the SBO procedures. We reviewed the plant list of CIVs and the licensee's SBO procedures. We did not find any valves in addition to those listed in the Catawba 22 i

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l SBO prc,eedures which do not meet the exclusion criteria listed in RG l.'155,

.. Therefore, Catawba has the ability to ensure that containment isolation can be provided during an SBO event, should it become necessaty.

6. Reactor Coclant imentory Licensee's Submittal Plant System The licensee performed a calculation using the MAAP computer code. The assumptions used in the calculation included an initial leak rate of ~110 gpm which

-decreased to ~30 gpm after four hours and did not include the make-up pump which can be powered flom the SSF diesel generator. In addition, the calculation considered the automatic injecticn of the upper head injection accumulators, which discharge water to the primary system at ~1250 psi, which occurs about 50 minutes into the SBC event. The results of the calculation show that the core will not become uncovered during a fou hour SBO event.

SSF Feature -

The licensee stated that the AAC source (the SSF diesel generator) powers the necessary make up system to maintain adequate reactor coolant system (RCS) inventory to ensure that the core is cooled for the four hour coping duration. A standby make up pump powered from the SSF diesel generator is located in the annulus of each unit to supply make up to the RCS. The licensee stated (13) that the pump is sized to accommodate normal system leakage, reactor coolant pump (RCP) sealleakage, and additional flow for system make up. The standby make up pump delivers borated water from the spent fuel pool to the RCS at a rate of 26 gpm. Approximately 18 gpm is required for normal sea! leakage and cooling, thus preventing the seals from degrading which would lead to the NUMARC postulated 23

3 .- ,

111 gpm sealleak rate, The remaining capacity of the pump (8 gpm) is available for RCS make up and boration.

Review of Licensee's Submittal Reactor coolant make up is necessary to replenish the RCS inventory losses due to the reactor coolant pump seal leakage (25 gpm per pump per NUMARC 87 00 guideline), and the technical specifications maximum allowable leakage (11 gpm).

The licensee provided (15) the results of its MAAP catculations which indicate that the core will not become uncovered during a four hour SBO event.

We performed a calculation to determine the adequacy of the reactor coolant inventory. Over four hours with a postulated constant 111-gpm leak rate, the RCS 3

would lose 26,640 gallons of water, which is -3600 ft . According to the plant 3

FSAR, the RCS liquid volume is 11,155 ft with the pressurizer 60% full (Table 5.1).

After four. hours with no cooldown, the RCS has 7500 ft3 of water remaining.

neglecting the accumulan s, We estimated that each steam generator contains 1080 ft3of primary coolan' ,d the pressurizer is contains 1080 ft3 of water (60% of the pressurizer volun.q. Therefore, after four hours, the pressurizer would be empty and each of the four steam generator would have. ~450 ft3 of primary coolant remaining. If cooldown is considered, the remaining 7500 3ft at 55"F would shrink to 6200 ft3at 350 F, which is a sufficient volume to maintain natural circulation and to keep the core covered and cooled during an SBO event. Therefore, even if the make up pump is not considered, the core will not become uncovered during an SBO event.

i NOTE:

The 25-gum RCP sealleak rate was agreed to between NUMARC nd the NRC staff pending resolution of Generic issue (GI) 23. If the final resolution of GI-23 defines higher RCP seal leak rates than assumed for the RCS inventory 24

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evaluntion,- the licensee needs to be aware of the potential impact of this =

resolution on its analyses and actions ~ addressing conformance to the SBO rule.

• 3N Proposed Procedure and Training - I a

Licensee's Submittal 4

- The licensee stated that the following procedures have been reviewed and the changes 4

necessary to meet NUMARC 87 00 guidelines will be implemented:

- 1.1 - Station blackout response,

2. AC power restoration, and '

, 3. :. Severe weather guidelines.

.. i Review of Licensee's Submittal

-We did not review the licensee's procedures in detail. We consider these procedures ito lie plant specific actions concermng the required activities to cope with an SBO. It is the licensee's responsibility to revise and implement these procedures, as needed, to mitigate an SBO event'and to assure that these procedures are complete and correct,'-

y andthat the associated training needs are carried out accordingly.  :

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7. *3.5. Proposed . Modification" f O I Licensee's Submittal-w g Tne licensee stated that no modifications or associated procedure changes are required

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Reelew of Lieensee's Submittal We did not find the need for any modifications in order for Catawba Nuclear Station to be able to cope with a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> SBO event, 3.6 Quality Assurance and Technical Specifiestions The licensee stated (15) that the SBO response equipment is classified into three Quality Assurance (QA) categories. The three categories are 10 CFR 50, Appendix B, w hich covers safety related equipment; 10 CFR 50, Appendix R, which covers fire and security-related equipment; and RG 1.155, Appendix A, which would cover the S80 equipment not covered in other categories. The licensee added that equipment covered by Appendices B and R meet the QA requirements of RG 1,155, Duke power is in the process of establishing a program which meets the requ! cement of RG 1.155, Appendix A, i

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4.0 CONCLUSION

S Based on our resiew of the licensee's submittals and the information available in the FSAR for Catawba Nuclear Station, we find that the submittal conforms with the requirements of the SBO rule and the guidance of RG 1.155 with the following exceptions:

1. Class 1E Hattery Ccpacity Our review of the licensee's class 1E battery capacity calculation produced the following concerns:

1. The battery loads assumed by the licensee are based upon the loads measured during a blackout test, not upon the rated loads of the equipment. The licensee needs to repeat the blackout test periodically and update its battery capacity calculation as needed, or provide assurance that the loads wnich could occur during an SBO esent would not exceed those measured during the test.

- 2. .in the calcelation, there is no last-mmute load increase. The last rninute toad L

represents the closure of the circuit breakers necessary to restore offsite power.

2- EDG Battery Capacity l Accordisc to the plant FSAR, the EDG batteries are designed to last for two hours.

The licensee needs to ensure that these batteries will have sufficient capacity for the EDG field hshing at the end of the SBO event.

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, .. . s 3, Loss of Ventilation AEW Pumn.R_00m The calculation for the AFW pump room was performed assuming the condiuons expected during SSF operation. This calculation, however, included a ventilation fan, The licensee needs to verify that this fan is DC-powered and will be available during an SBO event.

Mechaniqalfsmgation Roorn We did not receive a calculation for the Catawba mechanical penetration room. We did, however, receive a calculation for the McGuire mechanical penetration room which produced the same final calculated temperature (188 F). The licensee needs to verity that this calculation is applicable to Catawba.

4

_ Control R_ nam The control raom will have heating and cooling available within 45 minutes once the control area HVAC system is aligned to the powered bus in the NBO unit. The licensee needs to verify that each emergency bus has the capability to power a ventiletion fan for each of the rooms within the control area. In addition, the licensee needs to open the control room cabine. doors within 30 minutes in the.

absence of air ccaditioning, consistent with the guidance.

. Switches;}LBpam -

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'Since the availability of HVAC to the switchgear room has not been formally documented, the licertsee needs-to verify that HVAC will be available in the switchgear toom within 45 minutes of the onset of an 5B0 event.

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5.0 REFERENCES

1. De Office of Federal Register, " Code of Federal Regulations Title 10 Part 50.63," 10 CFR 50.63, January 1,1989.

2. U.S. Nuclear Regulatoly Commission, " Evaluation of Station Blackout Accidents at Nuclear Power Plants Technical Findings Related te, Umesolved Safety Issue A 447 NUREG 1032, Baranowsky, F.W., June 1988.

3. U..S. Nuclear Regulatory Commissioth " Collection and Evaluation of Complete and Partial Losses of Offsite Power at Nuclear Power Plants," NUREG/CR 3992, February 1985.

4. - U.S. Nuclear Regulatory Commission, " Reliability of Emergency AC Power System at Nuc! ear Power Plants," NUREG/CR 2989, July 1983.

5. -U.S. Nuclear Regulamry Ccmmission, " Emergency Diesel Generator Operating Experience, 1981-19837 NUREG/CR 4347, December 1985.

6. U.S. Nuclear Rcgulatory Contmission,MS:ation Blackout Accident Analyses (Part of NRC Task Action Plan A-44)," NUREG/CR 3226, May 1985.

7. U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research,

" Regulatory Guide 1.155 Station Blackout," August 1988.

m -

8. Nucleer Management and Resources Council, Inc., " Guidelines and Technical Bases for-NUMARC Initiatives Addressing Station Blackout at Lig'at Water Reactors." NUM ARC 87-00, November 1987 L 29 l

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9. Thadani, A. C., Letter to W. H. Rasin of NUMARC, " Approval of SUMARC

Documents on Station Blackout (TAC-40577)" dated October 7,1988,

10. Thadani, A. C., letter to A. Marion of NUMARC," Publicly Noticed Meeting December 27, 1989," - dated January 3,1990, (confirming "NUMARC 87-00 Supplemental Questions / Answers," December 27,1989).

11. Nuclear Safety Analysis Center, 'The Reliability of Emergency Diesel Generators at U.S. Nuclear Power Plants," NSAC 108, Wyckoff, H., September 1986.

12. Tucker, H. B., letter to U.S. Nuclear Regulatory Commission Document Control Desk,

' Requirements for Station Blackout," dated Apnl 17,1989.

13. Tucker, H. B., letter to U.S. Nuclear Regulatory Commission Document Control Desk, "Reauirements for Station Blackout (SBO)," dated April 4,1990.

14 Catawba Nuclear Station Final Safety Analysis Report,1990 Revision.

15. Supplemental information provided by the licensee following the meeting in Charlotte, NC. ,

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