ML20062A575

Safety Evaluation Re Station Blackout Rule.Util Response Does Not Conform W/Station Blackout Rule

ML20062A575
Person / Time
Site:	Arkansas Nuclear
Issue date:	10/10/1990
From:	NRC
To:
Shared Package
ML20062A554	List: ML20062A551 ML20062A575 ML20062A588
References
NUDOCS 9010220181
Download: ML20062A575 (14)

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ENCLOSURE 1 ARVANSAS NUCLEAR ONE, UNIT 1 (ANO-1)

STATION ELACKOUT SAFETY EVALUATION REPORT.

1.0 INTRODUCTION

On July 21, 1988, the Code of Federal Regulations'10CFR Part 50, was amended to include a new Section 50.63, entitled Loss of All Alternating Current Power,"

(StationBlackout). Thestationblackout(580)rulerequiresthateachlight-water-cooled nuclear power plant be able to withstand and recover from an SB0 of specified duration, requires licensees to submit information as defined in 10 CFR Part 50.03 and requires licensees to provide a plan and schedule for '

conform 6nce to the SFO rule. The SE0 rule further requires that the baseline assumptions, analysis and related information be available for NRC review.  ;

Guidance for conformance to the rule is provided by (1) Regulatory Guide (RG) 1.150, Station Blockout, (2) HUMARC 87-00, Guidelines and Technical Bases for NUMARC Initiatives Addressir,g Station Elackout at Light Water Reactors, and (3) NUPARC 87-00 Supplemental Questions / Answers and Major Assumptions dated DecembLr 27,1989 (issued to the industry by NUMARC' January 4,1990).

TofacilitatetheNRCstoff's(hereafterreferredtoasstaff)reviewof licensee responses to the SB0 rule, the staff endorsed 2 generic response formats. One response format is for use by plants proposing to use an Alternete AC (AAC) power source and the other format is for use by plants  ?

propcsing an AC independent response. The generic response formats provide the staff with a suranary of the results from the licensee's analysis of the plant's SB0 coping capability. The licensees are expected to verify the accuracy of the res'ults and maintain documentation that supports the stated results.

Compliance to the SB0 rule is verified by a review of the licensee's submittal, an audit review of the supporting documentation as deemed necessary, and possible followup NRC inspections to ensure that the licensee has implemented the appropriate hardw6re and/or procedure modifications that will be required to comply with the SB0 rule.

• Nucicar Management and Resources Council, Inc.

9010220181 901010 PDR ADOCK 05000313 P PNV

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1 For Ah0-1, the licensee has proposed using existing emergency diesel generators I (EDGs) as an AAC power source and has submitted its response in the applicable generic response fonnat. The licensee's original response was provided by letters from T. G. Campbell (Arkansas Power & Light Co.) to U. S. Nuclear Regulatory Commission (NRC) dated April 13, 1989. In addition, the licensee provided responses to the NUMARC 07-00 Supplemental Questions / Answers by letters from N. S. Cains and J. J. Fisicato to NRC dated April 3, and July 17, 19EO. The licensee responses were reviewed by Science Applications International Corporation (SAIC) under contract to the NRC. The results of the review are documentedbyaSAICTechnicalEvaluationReport(TER),SAIC-90/1074, Arkansas Nuclear One, Unit 1 Station Blackout Evaluation," dated Septen.ber 17, 1990 (AttochmentNo.1).

2.0 EVA L UATION:

After reviewing the licensee's SB0 submittal and the SAIC TER, the staff concurs with the conclusions as identified in the SAIC TER'(refer to Attachment No.1 for details of the review). Based on this review, the staff findings and reconandations are sunimerized as follows. '

2.1 MationBlackoutDuration The licensee has calculated a minimum acceptable stattun blackout duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> t,esed on an offsite power design characteristic group of "P1", an  ;

Emergency AC configuration group "C", and an EDG reliability target of .95.

The target EDG reliability was based on ANO Unit 1 EDGs having an average reliability greater than 0.95, 0.94 and 0.90 over the last 100, 50 and 20 demands respectively. The P1 grouping is based on an independence of offsite power classification of Group l 1/2", a severe weather (SW) classification of-Group *2" and an extreniely severe weather (ESW) classification of Group "_1".

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After reviewing the availetle information in the licensee's submittal, RG 1.155, NUMARC 87-00 and SAIC's TER, the staff agrees with the licensee's evaluatier. of a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> SB0 coping duration.

2.2 Alternate AC (AAC) power Source l l

The licensee has proposed using existing EDGs as an AAC power source to operate systems necessary for the required SB0 coping duration and recovery therefrom.

2.2.1 Genert1 Staff Position on AAC power Sources  !

The definition in 10CFR 550.2, RG 1.155 and NUI' ARC 87-00 define AAC power scurce in tern;s of four attributes: (1) connections to the of fsite or the onsite /,C power systers, (2) minimum potential for comon cause failure with '

offsite pcrer or the ensite emeroency AC power sources, (3) timely avail-ability, and (4) required capacity and reliability. More specifically, in _

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regard to the fcurth attributt, the SB0 rule reads as follows

"(4) H6ssufficicrt capacity ar.o reli6bility for operation of ull systers rcquired for coping with station blackout and for I the time required to bring and u.aintain the plant in safe shut- l cown (non-desigr basis accident)."

In view of the variety of types, capacities ar,o capabilities of power sources i proposed as AAC sources by varicos licensees, the staff has characterized pro- l posed AAC power sources as being either optimum, fully capable or' partially j

( Capable. This characterization, which relates only to the capacity attribute i I

cited above, was necessery in order to facilitate the staff review of-licer.see responses to the SB0 rule. It does not. invalidate or revoke any of the reouirements or guidance applicable to AAC power sources. i An optimum AAC power source cesign is one thLt is capable of' powering simultan- I eously both safety trains of nrrmal safe ' shutdown systems and equipment. Such i

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a design, following actuation of the AAC source, would provide completely re-cundant normal safe shutdown capability during an SB0 and recovery therefrom from the thin control room.

A fully capable AAC power source design is one that is capable of powering at least one complete safety train of normal safe shutdown systems and equipment. l This includes decay heat removal, battery charging, HVAC (heating, ventilation )

and air conditioning), emergency lighting, and the associated controls and I instrumentation. Thus, althcugh redundar,t capability is not available, a fully Capablt AAC source would enable attainment of safe shutdown durine an SB0 and recovery theri.from from the main control room.

A minimally capable AAC power source design is one that is not capable of powtring all (or any) norm 61 safety train related safe shutdown equipment; but it is capable of pwering specific equipment that, in conjunction with extensive manual crerator actions both inside and outside of the control room, is critical for attaining safe shutdown during ar. SDO. Appendix R diesels proposed as an AAC source are examples of minimally capable AAC sources.- With this design, operability of the main control room could not be assured unless the batteries were sized to operate for the SB0 duration, or battery charging capatility was piovided by the AAC source.

2.2.1.1 EDGs Used as AAC Power Sources The guidance en the use of existing emergency diesel generators (EDGs) as AAC power sources is documented in the station blackout rule 10 CFR $50.63, RG 1.155 Position C.3.3.5 end NUMARC 87-00 (Section 2.3.1(3). This guicance is further explained in NUl ARC 87-00 Supplemental Questions and Answers dated December 27, 1909, under cuestions 3.4 and B.3. The station blackout rule states: *

"At multi-unit sites, where the combination of emergency ac power j sources exceeds the minimum redundancy requirements for safe shut-l down (non-DBA) of all units, the remaining emergency ac power sources may be used as alternate ac power sources provided they meet the f

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epplicable requirements."

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The rule statement requires minimura redundancy. This means that in order to qualify as an AAC source, there must be an EDG available in the non-blackout (NB0) unit that is in addition to the number of EDGs required to meet the min-imum EDG redundancy requirement for powering a normal safe shutdown for a loss of offsite power (LOOP) event. Thus, the EDG's in a two unit site with two dedicated EDG's per unit would not qualify as AAC sources because the two EDGs- I per unit just meet the minimum redundancy requirement, i.e., there is no excess EDG.

However, there are some plants at two unit sites which just meet minimum re- .

dundancy but where each EDG is of sufficient capacity to fully power all the normal LOOP loads of the NB0 unit, and also has sufficient excess capacity for powering the required safe shutdown loads of the SEC unit. In recognition of the existence of this type of situation, the staff has interpreted the excess EDG redundancy requirement of the 500 rule to allow EDGs just neeting the  !

minimum EDG redundancy requirements, to qualify as AAC sources on the basis of excess cepacity, provided the other applicable' requirements for AAC sources are also met.

The NRC's basic position on the use ci EDGs as AAC power sources on the basis of excess capacity is that such excess capacity should not be attained by load shedoing in the NB0 unit which results in a degradation of its normally avaii-able safe shutdown capability for the luss-of-offsite-power (LOOP) condition.

Any actions that would add to the burden of operators that are already in a l high stress environment, such as load switching or disablement of information l read-outs or alarms in the control room, are considered to be a degradation of normal safe shutdown capability for LOOP in the NB0 unit. The staff position 1 is therefore that the normal equipment compliment should remain-available with edequate EDG capacity for use should it become necessary. The NB0 unit should I have the capability for hot shutdown / hot standby forced cooling..cooldown and depressurization as required. While additional events are not explicitly being postulated, it is not prudent to diminish the capability of the NB0 unit i to mitigate problems should they arise. It is not in the interest of safety to-. l t

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6-reduce the capability to handle various eventualities in one unit for the purpose of meeting the SB0 rule in another unit. Each unit must meet the SB0 rule on its own merits without reducing another unit's capability to respond to its own potential prob! sis.

Therefore, a multi-unit site with the dedicated EDGs just meeting the minimum-redundancy requirement but not having the excess capacity defined above for ,

qualifying as an AAC scurce does not meet the SB0 rule AAC source option requirunents. Further measures are required such as a separate AAC source or a coping analysis which shows the plant can cope with and recover from an SB0-for the required duration independent of AC power.

2.2.1.2 Connectability of AAC Power Sources The basic criteria governing the connectability of an AAC power source are contained in 10CFR 50.2 (The AAC source should be connectable to but normally not connected to the offsite or onsite emergency AC power systems),10CFR 50.63 (SB0 should not assume a concurrent single failure or design basis accident.),

end in Appendix A of 10CFR 50 (The single failure criterion and the independence requirtinents apply to the NB0 unit.). Therefore, in a one unit site as a minimum an AAC source need only be connectable to one-set of safe j shutdown equiprint, regardless of whether that equipment is ptrt of a safety train or not, or whether the AAC source is an excess redundancy EDG or an ino'ependent power source. '

1 However, at a two (or more) unit site where the EDGs meet the AAC source excess redundancy criterion, one intertie circuit between units is acceptable provided it is separately ccnnectable to each safety (EDG) bus in both units.- This follows from the application of the above criteria and the assumptions that must be taken that an SB0 can occur in either unit, and that the single failure-in the NB0 unit can be on either one of-its EDGs or on its respective safety I bus.

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l 2.2.2 Proposec' AAC Power Source The ANO Station is a two unit site with two dedicated EDGs per unit. The pro-posed AAC power source for the blacked out unit is a cross-tied EDG from the HBO unit.

The licensee's submittal states that the EDG/AAC source is available within I hour of the onset of the SB0 event, and has sufficient capability to provide power for safe shutcown of both units for a 4-hour 500 duration. The I licensee's submittal statea thet load shedding is required in the NB0 unit in ordtr to achieve this EDG capability ar.d has, therefore, proposed a load management scheit.e to power the needed equipment for safe shutdown operation of the blacked-out unit and NB0 unit. No details of the load shedding scheme were trovioed. The staff has reviewed the licensee's response (see Attachment 1 for details) and has concluded that the lood shedding scheme will result in the degradation of soft shutdown cap 6bility of the NB0 unit and the excess capacity made available by load shedding cannot be credited as an AAC source for the blacked out unit. Therefore, the licensee's proposed actions do not conforneto the guidance on the use of existing EDGs on the basis of excess capcuty as an  ;

AAC power sources as documented in the 10 CFR $50.63, RG 1.155 Position j C.3.3.5, NUMARC 87-00 section 2.3.1(3), and HUI' ARC 87-00 'Supplenental Questions !

and Answers dated December 27, 1989. i i

Af ter reviewir.g tne SAIC TER and the licensee's proposed actions for crediting-existing NB0 unit EDGs es an AAC source, the staff has determined that the pro-pcsed AAC scurce for AH0-1 does not meet the requirements of 10 CFR 550.63. )

Recommendation: The licensee should undertete further measures such as pro-viding a separate AAC power source or a coping analysis which shows that the l plant can cope with and recover from an SB0 for the required duration inde- ,

pendent of AC power. I l

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Station Blackout copino Carability l

l The characteristics of the following plant systems and components were reviewed ,

to assure that the syster:s have the availability, adequacy and capability to achieve end n.aintain a safe shutdown and recover from an SB0 for a 4-hour coping duration.

i 2.3.1 Condensate Inventory for Decay Heat f<emoval i

The licensee's submittals states that 56,804 g611ons of cor.densate are required to remove decay heat from the reactor at ANO Unit I during a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> SB0 event.

The minimur condensate storage tank (CST) cepacity corresponding to minimum '

level per Technical Specifications for the unit is 107,000 gellons.

I After reviewing the licensee's submittal and the SAIC TER, the staff agrees with the licensee's assessment th6t the plant has adequate condensate inventory foi 6 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> SB0 dur6 tion. In addition, the excess inventory available in the CST is available for SB0 recovery. However, there is rio assurance that the ccndensate li.ventory can be used for the full 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> duration, because the decay _ ,

heat renovel system would nct continue to operate if the Class 1E batteries are  !

cepleted (See Section 2.3.2) af ter one hour since the charging source for the j battery (the AAC power source) does not meet the requirenents of 10 CFR 550.63. l 2.3.2 Class 1E Luttery Capacity The licensee stated that a battery capacity calculation was performed to verify that the Class 1E batteries have sufficient capacity to meet the SB0 loads for one hour. It is assumed that the AAC power source energizes a battery charger associated with one division within one hour.

Based upon the steff review, the licer.see's proposed AAC power source does not meet the requirertnts of 10 CTR $50.63 and, therefore, cannot be assumed to power e battery charger within ene hour. In accordance with NUllARC 87-00 Supplemental Questions / Answers, the-licensee should ensure that the nomal-A

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.g-battery backed plant monitoring and electrical system controls remain opera- I tional for successfully coping with and recovering from a SB0 event. The licensee has not demonstrated that the Arkansas Unit 1 batteries have sufficient capacity to last for the full 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> SB0 duration without charging. Also, the 1 licensee has not provided en acceptable AAC source that meets the requirement of 10 CFR 50.63 for charging the batteries.

Recomendation: The licensee should provide for ANO-1 an acceptable AAC power.

source to power battery charging for at least one division or provide a battery-that has sufficit.nt capacity to power all normal battery-backed monitoring and r electrical systens and controls for the required 4-hour SB0 duration and recovery therefrom.

2.3.3 C upressed Air The licensee stated that no air operated valves are relied upon to cope with an SFO for one hour. Theturbinedrivenauxiliaryfeedwater(AFW)' pump,and atmospheric dump valves (ADVs) are relied upon for decay heat removal during an SEO.

ADVs are air operated, ADV block valves are motor operated, and the AFU flow control valves are de motor operated valves. There is no mention of the ADVs or ADV block valves being equipped with,handwheels that-can be used to control the decey heat release rate manually upon loss of power.

i After reviewing the licensee's proposal and the SAIC TER, tr,e staff agrees with i SAIC assessment that the licensee does not have an AAC source for ANO-1 that meets the requirements of the SB0 rule (see Section 2.2.2 above) which powers t the equipment for air make up capability to operate the ADY valves needed for i j

decay heat removal.

i Recommendation: The licensee should provide an acceptable AAC for ANO-1 source that meets the SB0 rule and provides n.e6ns'for. powering the equipment i for air make up to operate the ADV valves or provide alternate means for j

achieving decay heat renio>al during an SB0 event. Whatever n,ethod 1s chosen, i

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the licensee should simulate the proposed procedure and provide the appropriate l operator training to ensure the decay heat removal can be adequately maintained. -l 2.3.4 Effects of Loss of Ventilation '

The licensee has stated in his submittals.cated April 13, 1989, and Apr11 3, 1990, that reasonable assurar.ce of the operability of SB0 response equipment in i dominant areas of concerns (DAC) including the control room, was assessed using

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Appendix F to NUMARC 87-00 and/or the Topical Report without taking credit _ for [

HVAC. However, the licensee, in his submittel deted July 7, 1990, has indicated that he has made the decisicn that the control room HVAC will be powered during  ;

an SB0 event. The licensee stated that supplying ventilation in one control roon. results~ in sufficient cooling in the other control room via opening between j the two control rocnis. Based on the licensee's statement', since Unit 2 control '

rooni HVAC system is powered f rom its EDGs, the staff concludes that the Unit 1 - ,

control room will be cooled by either of the Unit 2 control room ventilation systems .

2.3.5 Containment Isolation Thelicenseestatedthatthecontainment-isolationvalves-(CIVs)whichmustbe  !

capable of being' closed cr operated under SB0 conditions can be positioned  ;

(with indication) independent of the preferred and_ blacked out unit's Class IE power supplies. After reviewing the SAIC TER, the staff agrees with the SAIC l

assessment that appropriate containment integrity is obtainable without any i operator action.

'e 2.3.6 Reactor Coolant invantory t

The licensee has stated that the ability to maintain adequate reactor. coolant j system (RCS) inventory to ensure that the core is covered has been assessed for i

.one hour, and after one hour, the proposed AAC source powers the RCS make-up syst eud. However the proposed AAC source does not cualify as an AAC source

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based on excess cepacity and, therefore, the assumption that AAC power source will pcwer the necessary make-up systems to maintain adequate RCS inventory is invalid. i l

I Recommendation: The licensee should provide for ANO-1 an acceptable AAC power source of sufficient capacity end capability to' provide power to the make-up systems and its supporting systems to maintain adequate RCS inventory or.

3 provide an assessment that there will be adequate RCS inventory to ensure continued core cooling for the required SB0 duration and recovery therefrom.

j 2.4 Procedures and Trainino The licensee has stateo that the appropriate procedures have been revieweu and i

raodified, furthermore, the licenset has stated that the changes will be implementeo by the end of refueling outage number 10 (October 23,1991).

i Although the licensee has completed appropriate procedures, additional procedures muy be required depending upon the licensee's proposed resolution of j the AAC power source (see section 2.2.2) issue.

The prcpesed procedure modifications indicated above were not reviewed, but the staff expects the licensee to maintain and implenient these procedures including any others that may be required as part of the revised response to ensure an appropriate response to an SB0 event. Although personnel training requirements for an SB0 response were not specifically addressed by the licensee's submittal, the staff expects the licensee to implement the appropriate training to ensure an effective response to the SBO.

2.5 Proposed Modifications:

The licensee stated that modifications will be necessary to cross-tie the ANO Unit I and 2 sofety buses in order to provide the AAC power scurce to the-blacked-out unit. The E0P procedure would require modification to align the 1

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operators. The AAC cross-tie modifications are planned to be completed by the.  ;

end of refueling outage No.10 depending on NRC response.

gconendation: The licensee's proposed AAC for ANO-1 does not conform to the i SB0 rule requirements, and therefore the licensee should consider the addition l

of an independent AAC source. The l'icensee should provide a full description including the nature and objectives 'of the required modifications to meet the S00 rule and a proposed schedule for implementatiori.

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2.6 Quality Assurance (OA) end Technical Specifications (TS)

The licensee aid not provide any information regarding QA programs and TS for j

SB0 equipment to the guidance of P.G 1.155, Appendices A & B. '

Furthermore, technical specifications for the SCO equipment are currently being i considered gererically by the NRC in the context of the Technical. Specification Improvnent Progrern and remains an open item at this tirne. However, the staff f would expect that the plant procedures will reflect the appropriate testing er.d surveillance requirements to ensure the operability of the necessary SB0' equip- _l raent. 11 the staff later determines that a-TS regarding the SB0 equipment is-warranted, the licensee will be notified of the implementatiun requirements.

Recorn ndation: The liccusee should verify that the SB0 equiprr.ent is covered by an appropriate QA progran consistent with the guidance of RG 1.155.

Further, this evaluation should be documented as part of the package supporting.

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the SB0 rule response. l 2.7 EDG Reliability Procram The licensee's submittals did not specifically address the EDG reliability ' pro-gram consistent with the guidance of RG:1.155, Section 1.2. It is the staff's-position that an EDG reliability program should be developed in accordance with the guidance of RG 1.155, Section 1.2.

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should be included in the documentation supporting the SB0 submittals that'is to be maintained by the licensee. >

2.8 Score of Staff Review The station blackout rule (10CFR 50.63) requires licensees to submit a response containing specifically defined information. It also requires utilities to have baseline assumptions, analyses and related information used in their coping evaluation available to f;RC. The staff and its centractor did not perform a detailed review of the proposed procedure modifications which are- '

scheduled for later implementation after the ircdifications that could result from the staff reconnendations in this SER. ~ Therefore, baseo on our review of the licensee SB0 submittal and FSAR, we have identified-the following areas for-f ocus in any follow-up inspection er assessment that may be undertaken by the NRC to further verify conformance with the SB0 rule,

a. Hardware and procedurol modifications.

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b. SB0 procedures in accordance with RG 1.155, Position 3.4, and NUMARC 87-00, Section 4,

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Operator staffing and trainine to follow the identified actions.  ;

in the SB0 procedures,

d. EDG reliability program meets as a minimum the_ guidelines of ,

RG 1.155,

e. Equipment and components required to cope with an SB0 are

! incorporated in a QA program that meets the' guidance of RG; ,

1.155, Appendix A, and

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f. Actions taken pertaining to the specific recommendations noted f above in this SER.

3.0

SUMMARY

AND CONCLUSIONS:

The staff has reviewed the licensee's response to the station blackout rule (10 CFR 50.63) and the Technical Evaluation Report prepared by the staff's consultant, Science Applications International Corporation. Based on our  ;

i review, we find that ANO-1 does not conform with the SB0 rule and the guidance of RG 1.155, and, therefore, recommend that the licensee reevaluate the areas of concern that have been identified in this SER. Guidance for.the licensee to review and implement the staff's recon.mendations is provided in RG 1.155,  !

NUMARC 87-00 and the supplementary guidunce (NUMARC 67-00 Supplementary Questions / Answers;NUMARC87-00MajorAssumptions).datedDecember 27, 1989,_

which was issued to the industry by NUMARC on January 4,1990. The staff's concerns that are identified in this SER should be addressed _by the licensee,.

and a revised response submitted to the NRC within 60 days. The staff has'not approved the use of existing EDGs as an AAC source on the basis of excess cap .

ecity made evailable by load shedding. The licensee is,-therefore, expected to ensure that the baseline assumptior.s of NUMARC 87-00 are applicable to the_AND plant. Also, the licensee is expected to document all- analyses and related information, and to maintain these available- for NRC review. ,

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. as ATTACHMENT 1-l l

l SAIC-90/1074 TECHNICAL EVALUATION REPORT ARKANSAS NUCLEAR ONE, UNIT 1 l STATION BLACKOUT EVALUATION l

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I TAC No. 68508 l 5/dC Science ApplicationsIntemationalCorporation An Employec Owned Company l

Finsi l l

September 17, 1990 y

-l Prepared for:

U.S. Nuclear Regulatory Comission Washington,' D.C. 20555

. Contract.NRC-03-87-ui l Task Order No. 38' j

1710 Goodridge Dove, RO. Box 1303. McLean, Virginia 22102 L (70318214300 co~e ss c one a v.aams owe covox sove oo,re nmm us w>n w amem oss no ons,.m reoairo se oueo sww on usae

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1 TABLE OF CONTENTS l Section- Egg

1.0 BACKGROUND

. . . . . ... . . . . . . . .-. . . . . . . 1 2.0 REVIEW PROCESS . . . . . . . . . . .-. ... . . ... . . 3 3 i

a 3.0 EVALUATION . . . . . . . . . . . . . . . . . . . . . .. -6 3.1 Proposed Station Blackout Duration. . . .... 6 i

3.2 Alternate AC (AAC) Power Source ...-. . . . . .-

. 9-3.3 Station Blackout Coping Capability. . . . . . . . 13 3.4 Proposed Procedures and Training; . . . . . . . . 19 3.5 Proposed Modifications. . . . . . . . . . . . . . 20 3.6 Quality Assurance and Technical Specifications. . 21.

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4.0 CONCLUSION

S. . . . . . . . . . . . .:. . . . . . . . . 22

5.0 REFERENCES

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TECHNICAL-EVALUATION REPORT  ;

ARKANSAS NUCLEAR ONE. UNIT 1 ,

STATION BLACK 0UT EVALUATION-

1.0 BACKGROUND

.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). Tiie objective of this requirement is to i assure that all nuclear power plants are capable of withstanding a station '

blackout (SBO) and maintaining adequate reactor core cooling and appropriate <

containment integrity for a required duration. This requirement-is based on information developed under the commission study of Unresolved Safety Issue A-44, " Station Blackout", (2-6).

The staff issued Regulatory Guide (RG) 1.155, " Station Blackout'," to .

provide guidance for meeting the requirements of 10 CFR 50.63 (7). Concurrent with the development of this regulatory 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 (8). This document provides detailed guidelines and procedures on how to assess each plant's . capabilities to comply with the SB0 rule. The NRC staff reviewed the guidelines and analysis methodology in

NUMARC 87-00 and concluded that the NUMARC document provides an~ acceptable guidance for addressing the 10 CFR 50.63 requirements. The application of this method results in. selecting a minimum acceptable SB0 duration capabil.ity .

from two to sixteen hours depending on the plant's characteristics and vulnerabiliues to the risk from station blackout. The plant's characteristics affecting the required coping capability are:- the. redundancy of the on-site emergency AC power sources, the reliability of 'on-site.

emergency power sources, the frequency of loss'of off-site power (LOOP), and 4 the probable time to restore off-site power.

In order to achieve a consistent systematic response:from licensees to '!

l the SB0 rule and to expedite the staff review process, NUMARC developed two 1

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generic response documents. These documents were reviewed and endorsed by the.

NRC staff (9) for the purposes of plant specific submittals. 'The' documents are titled:

1. " Generic Response to Station Blackout Rule. for Plants Using Alternate AC Power," and

2. " Generic Response to Station Blackout Rule for Plants Using AC  :

Independent Station Blackout Response Power."

4 A plant-specific submittal, using 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 applicable to-their plants and to-verify l the accuracy of the stated results. Compliance with the ~SB0 rule requirements is verified by review and 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- '

1 meet the SB0 rule.

1 In 1989, a joint NRC/SAIC team headed by an NRC staff member. performed audit reviews of the. methodology and documentation that. support.the licensees'  ;

submittels for several plants. These audits revealed several deficiencies j which were not apparent from the review of the licenseessubmittals using.the.

agreed upon generic response format. These ' deficiencies . raised a generic'-

question regarding the degree of the licensees' conformance to thel requirements of the SB0 rule. To resolve this question..on January 4, 1990, NUMARC issued additional guidance as NUMARC 87-00-Supplemental

, Questions / Answers (10) addressing the NRC's concerns regarding'the l deficiencies. NUMARC requested that the 1icensees send .their supplemental -

1 l responses-to the NRC addressing these' concerns by March 30,E1990.

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2.0 REVIEW PROCESS The review of the licensee's submittal'is focused on the following areas consistent with the positions of RG l.155:

- t A. Minimum acceptable SB0 duration (Section 3.1),

B. SB0 coping capability (Section 3.2), ,

C. Procedures and training for'SB0 (Section 3.4),

D. Proposed modifications (Section 3.3), and 1

E. Quality assurance and technical specifications for SB0 equipment '( '

(Section 3.5).

For the determination of the proposed minimum acceptable SB0' duration, the following factors in the licensee's submittal'are reviewed: a) off-site power design characteristics, b) emergency AC power system configuration, c) determination of the emergency diesel generatorL(EDG) reliability consistent with NSAC-108 criteria (11), and d) determination of the accepted'EDG target reliability. Once- these factors are known, Table 3-8 of NUMARC 87-00 or Table 2 of RG 1.155 provides a matrix.for determining the required coping.

duration.

i For the SB0 coping capability, the licensee's submittal is reviewed to.

assess the availability, adequacy and capability of the plant' systems and-components needed to achieve and maintain a safe shutdown condition and < '

recover from an SB0 of 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, t

c. availability of adequate compressed air for air-operated valves-necessary-for safe shutdown, 1

d. adequacy of the ventilation systems in the vital and/or dominant areas that include equipment ~necessary- for safe shutdown-of the plant,

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e. ability to provide appropriate containment integrity, and

f. ability of the plant to maintain adequate . reactor coolant system  !

inventory to ensure core cooling for the required coping' duration. .

The licensee's submittal is reviewed to verify that required procedures -[

(i.e., revised existing and new) for coping'with'SBO are identified and that.  !

appropriate operator training will be provided. .1

'The licensee's submittal for any proposed modifications to emergency AC -

sources, battery capacity, condensate capacity, compressed air capacity, appropriate containment integrity and primary coolant make-up capability is 3 reviewed. Technical specifications and quality assurance set forth'by the  !

l licensee to ensure high reliability. of the equipment, specifically added or '

l assigned to meet the requirements of the SB0 rule, are assessed;for their  !

adequacy.

The licensee's proposed use of an alternate'AC-power source'is reviewed.

t l

to determine whether it meets the criteria and guidel;nes of-Section 3.3.5 of RG 1.155 and Appendix B of NUMARC 87-00.

1 This SB0 evaluation is based on a review'of:the licensee's submittals dated April 13, 1989 (12), April 3, 1990 (14),land July 17;-'1990.(13),a-telephone conversation between the NRC/SAIC and the -licensee .on August 10, 1990, and the available information in the plant Updated Final Safety Analysis Report (UFSAR) (15). The evaluation does not include-a' concurrent site audit-

'4

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review of the supporting documentat. ion. Such an audit may be warranted as an. j additional confirmatory action. This determination would.be made and the audit would be scheduled and performed by the NRC staff at some later date'.-

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l 3.0 EVALUATION i 3.1 Proposed Station Blackout Duration i

Licensee's Submittal i

The licensee, Entergy Operations, Inc. (formally Arkans'as Power and Light 1 Company), calculated -(12-14) a minimum acceptable station blackout-duration of four-hours for the Arkansas Nuclear One (ANO), Unit 1. 'The.  ;

licensee stated that no modifications are necessary to attain this.; }

proposed coping duration. ,.

The plant factors used to calculate the proposed SB0 duration are:

1. Off-site Power Design Characterist,cs The plant AC power design chara:teristics group is "Pl" based on:

a. Estimated % quency of LO3Ps due to extremely severe weather.

(ESW) which places the p' ant in ESW Group "1,~"- t

b. Estimated frequency of LOOPS due to severe weather (SW).which: [

places the plant in SW Group "2," an'd-

c. Independence of the plant off-site' power system characteristic of "II/2," and d.

Expected frequency of grid-related LOOPS of less than one per '

20 years, ^

2. Emergency AC (EAC) Power Configuration Group t

The EAC power configuration group at Arkansas Nuclear One is "C."

Each unit is equipped with two emergency; diesel generators. One 1 6- I l

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, i emergency diesel generator per unit is'necessary to operate safe shutdown equipment following a LOOP.

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3. Target Emergency Diesel Generator Reliability  ?

The licensee selected a target EDG reliability of 0.95 based on_  !

having a unit average EDG reliability'for the :last 100, 50, and 20 i demands of greater than 0.95, 0.94, and 0.90 respectively, consistent with NUMARC 87-00. >

The licensee submittals do not address a diesel generator i reliability program incorporating the five elements discussed in RG. , 'j 1.155. However, the licensee does recognize'that the target. I reliability is to be maintained-(14).- The methodology of ,

maintaining the target is tied to' the resolution of Generic Safety  ;

Issue B 56. . 3 i

Review of Licensee's Submittal I s

Factors which affect the estimation ofithe SB0 coping duration are: 'the ,

j independence of the offsite power system grouping,'the estimated i l frequency of LOOPS due to ESW and SW conditions, the' expected frequency l of grid-related LOOPS, the classification of: EAC, and the' selection of l l EDG target reliability. The licensee's estimation:of the' frequency of LOOPS due to ESW condition- conforms with th'at.given in Table :3-2 of-NUMARC 87-00.

Using Table 3-3 of NUMARC 87-00, the expected frequency of LOOPS at ANO due to SW condition is estimated to be "0.0341" or-"0.0072" placing the. 3 site-in an SW group "4" or "2' depending-on theisite having' offsite power transmission lines eithw on'one or mult41e rights-of-way, respectively.;

.)

The licensee's submittal stated that the. plant is-in SW group ~'"2" '

i indicating that the sitt has power' transmission. lines.on multiple _ rights -

of-way. A review of the Unit 1 UFSAR indicates that'the site could be-

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-e considered to have transmission lines on multiple rights-of-way.

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Our review of the-ANO Unit 1.-UFSAR, combined with information-gained from the licensee during a phone conversation on August 10, 1990, indicates a that the. independence of offsite: power for ANO .is "II/2" based on:- '

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1. All offsite power sources are connected to the plant through-two l electrically connected switchyards.

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2. There are.two emergency safety-feature (ESF) divisions in each unit,  ;

and both divisions are n'ormally powered from the- unit auxiliary '  !

transformer (UAT). ..

3. The UAT for each unit.is connected to the unit main generator. 4 i

4. Upon loss of the main generator, a fast automatic transfer occurs- to' one of two start-up transformers. Unit I would^ normally. transfer- to STl (see Figure 1) which is' powered by the Auto Transformer. The  !

Auto ~ Transformer can take. power from either the 500.kV or 161 kV. d buses.  :

5. Should the selected start-up transformer fail,~ load can be manually

! transferred to the backup start-up transformer, which is normally  :

1 i

ST2. ST2 can support the safe shutdown loads of one unit plus the design basis accident (DBA) loads of the other~ unit.

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 U.S. indicates that ANO did not..

have a grid-related LOOP up to 1984.- In the absence of any contradicting I information, we agree. with the licensee's; statement that the' frequency of:

grid-related LOOPS is expected to be'less than one-per 20 years. .<

1 Our review of the ANO Unit 1 UFSAR indicates that the' licensee has. 1 properly classified the EAC classification as'"C" based on the facts that 8 ,

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Gere are two emergency AC power supplies for each unit and one emergency AC supply is necessary to operate safe shutdown equipment for each unit.-

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The licensee's determination of target emergency diesel generator ,

reliability is in accordance with RG 1.155 and.NUMARC'87-00. Although ,

the need to maintain the reli:bility of.the EDGs is recognized by the I licensee, no specific program was committed to. We take the licensee statement to maintain target reliability 'as a commitment to establish a l reliability program consistent with resolution of the Generic Safety Issue B-56.

d Based on the above, the AC power design characteristics of the ANO site-is "Pl" with.a minimum required SB0 coping duration of four hours.

3.2 Alternate AC (AAC) Power Source Licensee's Submittal The licensee stated that the'AAC power source at ANO will be an emergency AC power source from the non blacked out unit which meets the criteria ,

specified in Appendix B to NUMARC 87-00 and'the assumptions in Section 2.3.1 of NUMARC 87-00 (12). The proposed AAC configuration at ANO.is shown in Figure 1. The licensee' stated.that with this configuration, including the proposed cross-tie modification, any one'of the blacked out.

unit's emergency buses can be energized manually .from either.of the emergency buses of the non-blacked out unit. The(AAC power source will be available within one hour of the onset of an SB0 eventLand,has I sufficient capacity to operate necessary safe' shutdown' systems for both-units. A load management scheme is being developed for..the AAC power source; the scheme is to be. submitted to'the'NRC sometime after mid-September of 1990 (14).

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.. S Review of Licensee's Submittal The licensee's proposed AAC power source configuration (Figure 1) conforms to a variation of an acceptable configuration provided in NUMARC l 87-00 Supplemental Questions / Answers under Question C.I .(10). The AAC .

power source, one of the site EDGs, meets all the required criteria in Appendix B of NUMARC 87-00 except for the following. cases:  :

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o Paragraph B.9 of Appendix B states, "the AAC power source shall be

... capable of maintaining voltage and frequency within limits l consistent with established industry standard-that will not degrade the performance of any shutdown' system or component. At a multi-  !

unit site, except for 1/2 Shared or 2/3 emergency'AC power  ;

configuration, an adjacent' unit's Class IE power source may be-used- l as an AAC power source for the blacked out unit if it is capable of:

powering the required loads at both' units."  ;

o Paragraph B.12 of Appendix B states, " ... the AAC system shall 'be demonstrated by initial test to be capable of powering required  !

shutdown equipment within one hour of a station blackout event." 1

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The guidance'on the use of existing EDGs as AAC. power sources.at multi-unit sites is documented in RG 1.155, Section 3;3.5,1NUMARC 87f00, I Section 2.3.l(3), NUMARC 87-00 Supplemental. Questions / Answers, Questions 3.4 and B.3, and further detailed in References 16,17,-~ and 18. In addition, the SB0 rule states-that at multi-unit sites where the combination of EAC power sources ' exceeds the minimum ' redundancy -

requirements for safe shutdown (non-DBA) of all units, the remaining-EAC i sources may be used as AAC sources' provided- that they meet the applicable requirements.

l The rule statement requires ' minimum . redundancy. ' This means.that in ]

l order for an EDG to qualify as an AAC source there must'bean EDG t available in the NB0 unit in addition to the-number of EDGs required tol meet-the minimum EDG redundancy requirement for powering a normal. safe 11 1 I

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1 shutdown lo ds following a LOOP event. Thus, the EDGs in a two-cnit site  !

1 with two dedicated EDGs per unit would not qualify as'AAC sources. Two EDGs per unit would meet only the minimum redundancy requirement, tnd there is no excess'EDG, i However, there are some plants at multi-unit. sites which'have EDGs that'  ;

just meet the minimum redundancy but each EDG has sufficient capacity to I power all the normal LOOP loads of the NB0 unit and also has sufficient i 1

excess capacity to power the required safe shutdown loads of the SB0 l

unit. Recognizing the existence of this type of situation, the-staff has interpreted the 'If teral' excess EDG, redundancy requirement of the SB0 rule to allow large capacity EDGs to qualify as AAC sources,' provided-other applicable requirements are met.

1 In order to take credit for this interpretation,:the'N'RC staff's basic position has been (16, 17,.and 18)-that:

1. no action should be taken that would exacerbate the already difficult situation in the NB0 unit. Any actions that make operator >j tasks more difficult such as load switching orLdisablement of information readouts or alarms in the-control room are also-considered to be a degradation of normal safe shutdown capability-- .i for LOOP in the,NB0 unit. And, i

2. excess capacity of' the EDG being designated as an AAC source should not be the capacity made av'ailable by shedding or not powering normal safe shutdown loads .in the NB0 unit.' Examples of such loads 4

[ are: motor driven auxiliary feedwater pumps; heating, ventilation L and air conditioning-loads; the power supply of the. plant computer; l one or more. sets of redundant ~ instrumentation; etc.. The' shedding of such loads ' constitutes degradation of the normal. safe' shutdown capability of the NB0 unit.

l It is not in the interest of safety to reduce the capability to handle various eventualities in-one unit for the purpose of meeting the SB0' rule 12 I

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in another unit. Each unit must meet the SB0 rule on its own merits.

without reducing another unit's capability to respond to;its own. 'i potential problems, i

The excess capacity of the EDG 1n the' NB0 unit that qualifies it as an-l AAC source is, therefore, 'only that available capacity within the normal:

continuous rating but above the EDG load represented by the complete contingent of safety related and non-safety related loads normally expected to be available for'the LOOP condition. '

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In its SBO supplemental information submittal '(13) the licensee stated -

that load shedding is required to ensure that selected SB0 equipment in ]

the blacked out unit could be powered from one of the EDGs inithe NB0 '

unit. During a telephone conversation on August 10, 1990, the licensee -l was asked by the staff to explain it's load management-scheme and how~that. ,

differs from the guidance.- The' licensee stated;that since.no conclusive ,

i determination had been made yet it could not supply the requested t information at that time. '

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Our review of the Unit 2 UFSAR regarding the required LOOP.and SB0 loads  ;

indicates that the each EDG at Unit 2 does not have sufficient / capacity -l to meet the above guidance without a' load shedding _ scheme. If these l loads were not shed, the AAC power source would notthave sufficient

capacity to power the' selected equipment'needed for safe shutdown operation of Unit 1. Therefore, the-licensee's proposed AAC power source does not conform to the requirements of-the SB0 rule.

I 3.3 Station Blackout Coping Capability j The plant coping capability for'the.. required duration of four' hours is.

. assessed based on the following results:

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1. Condensate Inventory for Decay Heat Removal i

t Licensee's Submittal  !

The licensee's submittal (12) stated thatl56,804 gallons of i

condensate are required to' remove decay heat from the reactor at ANO Unit I during a 4-hours SB0 event. The minimum condensate storage tank.(CST)-level per. technical specifications is 107,000 gallons. I Sufficient condensate inventory exists for decay heat removal.during  ;

a 4-hour 580 event.

Review of Licensee's Submittal We performed a calculation of the required condensate inventory based on NUMARC 87-00. Our results confirmed the -licensee's. stated values and the fact that sufficient condensate inventery-exists for ,

decay heat removal during a'four. hour SB0 event. However, there is no assurance that the decay heat removal (DHR) system at ANO Unit 1 4

l would continue to operate after the' Class lE. batteries are depleted.

The batteries are expected to last two hours, (see item 2 below).

l The licensee needs to verify that the DHR systems'.will~ remain opercticr.a1 and controllable after the batterie's are depleted.

2. Class 1E Batter,< Capacity Licensee's Suhnittal The licensee stated that a battery capacity calculation has been performed to verify that the class'lE batteries have sufficient capacity to meet the station blackout loads for.one hour . j 1

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. s j Review of Licensee's Submittal  !

The licensee states that the Class IE batteries.have sufficient 1 capacity to meet the SB0 loads for one hour.' The Unit 1 UFSAR (15)  ;

indicates that the class IE batteries are sized to provide power to }

essential DC loads for two hours without.being charged. However, the batteries are needed to supply the~ connected loads for four  ;

hours. Since the proposed AAC power source does not conform to the requirements of the SB0 rule, it cannot be assumed that a battery

. charger will be available to support DC loads and the batteries will

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be depleted sometime after one hour into an SB0 event. To conform with the guidance provided in NUMARC 47-00 Supplemental ~

Questions / Answers, the licensee needs to ensurc that the normal-battery-powered plant monitoring and electrical system controls  ;

remain operational for successfully coping with and recovering from:  ;

an SB0 event. Therefore, the licensee needs to. provide battery'-

charging capability.

3. Compressed Air i

Licensee's Submittal.

i The licensee stated that no air-operated valves are relied upon to ,

cope with a station blackout for one hour._

Review of Licensee's Submittal. .

Our review of the UFSAR indicates that all safety related air-operated valves.were found to go to the safe position upon-a loss of air. The valves required to operate in order to. cope with an SB0

-are those associated with the-auxiliary feedwater (AFW)-and-atomspheric dump systems. The AFW control valves are DC powered motor operated _ valves. The atmospheric dump valves are air operated and their block valves are' motor operated. The UFSAR indicates that' the ADV block valves are supported by the emergency. power system. -

15

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However, no mention is made on the capability of' manual operation of  ;

either the ADVs or their block valves upon loss of power.- 1 Since the AAC power source doe's not conform to the requirements of the SB0 rule, neither. compressed air nor electrical power are available. The licensee needs to provide:an explanation of the method it intends to use to remove decay' heat. If manual valve manipulation is involved, concerns:related to the~ habitability of the area of the valves, communication with the control room,- I procedures to operate the decay heat removal system in this manner, and the related operator training need to be addressed. 1 Alternatively, the license.needs to provide an AAC power source to.

support the operation of the decay heat removal system.

4. Effects of Loss of Ventilation l Licensee's Submittal

[

The licensee stated (12) that during an SB0 event no heating, ventilation and air conditioning (HVAC) . systems would be available to the following dominant areas of concern:

l Emergency Feedwater (EFW) pump room j Primary make up pump rooms Service water pump structure l Control room.

Room 99-(DC Elec. Equip.)

Room 109 (DC Elec. Equip.)

1 in a subsequent submittal'.(13) the licensee stated that the' control room HVAC will be powered by the AAC power source during an_ SBO.-

The licensee also stated it has performed a scoping analysis which

' indicates that the Unit 1 LOCA/HELB containment temperature profile envelops the SB0 condition.

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. 9 Reasonable assurance of the operability of station black out response equipment in DACs was_ assessed by the licensee using-Appendix F to NUMARC 87 00 and/or the Topical Report as well as analyses previously performed.

Review of Licensee's Submittal i

The information provided by the licensee and.that available in-the plant UFSAR is insufficient to make a judgement regarding .the >

correctness of the licensee's. stated results. The licensee only; ,

provided the final steady-state temperatures for the EFW pump room  !

(131'F) and the control room (<120 F). No other information is .

provided regarding other areas evaluated. Therefore, an audit.may l l

be required to confirm compliance, During the telephone conversation on August 10, 1990, the.licenseei vas asked to explain the selection of dominant areas of concern.

The licensee stated that the analysis is stil1Lunder review and!it-was not ready to' discuss the subject. With regard to the control room, the licensee stated that supplying, ventilation to.either

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control room.results in sufficient cooling in the other control room

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via openings between the two control rooms. The-licensee elaimed- '

l that it has an analysis demonstrating that aiventilation system in either control room can cool both control-rooms.

i Based on the licensee's statement,'and the fact that the. Unit 2 i control room HVAC system is powered from both Unit EDGs, we conclude that the Unit I control room will be ' cooled by one of the Unit 2 l control room ventilation systems.

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5. Containment Isolation ,

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Licensee's Submittal

. a The licensee reviewed the plant ~ list of containment isolation valves (CIVs) to verify that valves wh'ich must' be capable of being closed f or operated-(cycled) under station blackout conditions can be- j positioned (with indication) independent of the preferred and <

blacked-out unit's classilE power supplies. The licensee stated-the.t no plant modifications'are necessary to-ensure that appropriate- 1 containment integrityLis provided under SB0 conditions.

Review of Licensee's Submittal An independent review of the CIVs was performed based on Table' 5-l' of the UFSAR.for Unit 1. After excluding.those CIVs that' conform to.

the criteria stated in RG 1.155, Section 3.2.7, no valves: requiring i closure capability were found. ,

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6. Reactor Coolant Inventory.

1

-Licensee's Submittal

• i

' i The licensee stated (12)-that the generic. analyses listed in.Section 2.5.2 of NUMARC 87-00, which are applicable. to ANO Unit'I were used _,

to assess the plants ability to maintain adequate reactor coolant. I system inventory.for one hour. The licensee concluded that the expected rate of reactor coolant inventory loss under SB0' conditions does not' result in core uncovering in an.SB0 event of-one hour.

Therefore, make-up. systems in addition to those currently :available. l under 580 conditions are not required.

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>. 4 Review of Licensee's Submittal Based on the licensee's statement' thtt reactor coolant inventory :l loss under SB0 conditions does not result in core uncovering in.an j hour, we interpret that the reactor make-up is applied, starting at one hour. Since the AAC power source does not conform to the requirements of the SB0 rule, no RCS make up will beavailable.

Therefore the-licensee needs to have an analysis to demonstrate that- d

-the core is not uncovered during.the four hour. coping period, considering a 25 gpm per reactor coolant pump seal leak rate plus the maximum allowed technical specification leakage.  !

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3.4 Proposed Procedures and Training ^

Licensee's Submittal The licensee stated that the following plant procedures have been J reviewed per guidelines in NUMARC 87-00, Section 4:

1

1. AC power restoration,

2. Severe weather, and.

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3. Station blackout response guidelines. '

The licensee listed the plant procedures'which fall 'in each of above j areas in the plant SB0 submittal. .The-licensee stated that procedures requiring changes in'the first two areas have been reviewed and modified if deemed necessary. Procedure: changes for.stationnblackout response have been reviewed and will be modified to reflect the changes resulting frorr "" 'anned modifications. All procedure. changes are planned to be l com, he end of refueling outage number 10 for Unit 1,-estimated-as ,,1991, subject to the NRC's approval of the modifications.

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d Review of Licensees Submittal i We neither received or reviewed the affected procedures. We consider these procedures as plant specific' actions concerning the required activities to prepare for or to cope with an SB0 event. We believe;it is 1 the licensee's responsibility.to revise'and implement'these procedures, d

as needed, to mitigate an SB0 event and to assure that these procedur'es l are complete and correct, and that the associated training needs are--  !

carried out accordingly. j 3.5 Proposed Modifications Licensee's Submittal i The licensee stated that ' modifications will be necessary to cross-tie'.the - ,

ANO Unit I and 2 safety buses in order to' provide the'AAC' power source to the blacked out unit. The modification will include:

1. Cabling between each unit's safety buses

2. Unit I switchgear modifications to accommodate-the cross-tie j

3. Unit 2 switchgear modifications to accommodate the cross-tie i Procedure changes for both units to address breaker alignment, load-shedding, coordination of activities, and realignment of power ~ supplies-when they become available; will be needed. The AAC cross-tie-modifications are planned to be completed by the end of refueling' outages No.10 at Unit 1 and No. 8 at Unit 2, subject to= the NRC's: approval of' the modifications.

Review of Licensee's Submittal The proposed cross-tie modification (see Figure 1) is consistent with an,

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acceptable configuration provided in Appendix C to NUMARC 87-00, -

Supplemental Questions / Answer: Figure B:of Sample AAC Configurations.

This modification allows the licensee to power one of the emergency buses i 20

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i of the blacked out unit from either of the EDGs of' the non-blacked out unit, i

3.6 Quality Assurance and Technical Specifications l The licensee's submittals do not document the conformance of.the plant's.  !

SB0 equipment to the guidance of.RG 1.155, Appendices A and B.

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4.0 CONCLUSION

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Based on our review of the licensee's submittals, a telephone conversction between NRC/ Salt and the licensee, and the information available is the plant UFSMs for Arkansas Nuclear One, Units 1 and 2, we find the su'umittal does not conform with the requirements of the SB0 rule for the following reasons:

1. Alternate AC Power Source The licensee's intended load shedding of the non blacked-out (NBO) unit is not in conformance with the requirements of the SB0 rule and the guidelines provided in RG 1.155, NUMARC 87-00 Supplemental Questions / Answers, and References 16, 17, and 18. The load shedding scheme will result in the degradation of LOOP safe shutdown capability of the NB0 unit. This excess capacity made available by  ;

load shedding could not be credited as an AAC source for the blacked out unit (see the discussion under the AAC power sobree in Section '

3.2). Therefore, the AAC power source does not have sufficient capacity to power the selected safe shutdown equipment in the blacked out unit.

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2. Class 1E Battery Capacity The plant UFSAR indicates that each class IE battery will last for two hours without being charged. However, the batteries are needed to supply the connected loads for four hours. Since the proposed AAC power source does not conform to the requirements of the SBO, it cannot be assumed that a battery charger will be available to power DC loads after the batteries are exhausted. To conform with the guidance provided in NUMARC 87-00 Supplemental Questions / Answers, the licensee needs to ensure that'the normal battery-backed plant monitoring and electrical system controls remain operational for successfully_ coping with and recovering from an SB0 event.

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Therefore, the licensee needs to provide a separate AAC power for supporting the required battery charger (s).

3 Compressed Air The licensee needs to provide the method it intends to utilize to remove decay heat assuming neither compressed air or electrical power are available.

If manual operation of valves is involved, the licensee needs to address related concerns which are d Section 3.3.

4. Reactor Coolant Inventory The licensee needs to evaluate the reactor coolant inventory with no make up for four hours, considering a leakage of 25 gpm from each reactor coolant pump seal plus maximum allowed technical specifications leakage.

No make-up capability _can be assumed due to lack of sufficient AAC capacity (see item 1 above).

5.

Quality Assurance and Technical Specifications The licensee's submittals do not document the conform plant's

8. SB0 equipment to the guidance of RG 1.155, Appendices A a 23

- "o d.

5.0 REFERENCES

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

2. U.S. Nuclear Regulatory Commission, " Evaluation of Station Blackout Accidents at Nuclear Power Plants - Technical Findings Related To Unresolved Safety Issue A-44,." NUREG-1032, Baranowsky, P. W., June 1988.

3. U.S. Nuclear Regulatory Commission, " Collection and Evaluation of Complete and Partial losses of Off-site Power at Nuclear Power Plants,"

NUREG/CR 3992, February 1985, i

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

5. U.S. Nuclear Regulatory Commission, " Emergency Diesel Generator Operating Experience, 1981-1983," NUREG/CR 4347 December 1985.

6. U.S. Nuclear Regulatory Commission, " Station Blackout Accident Analyses (Part of NRC Task Action Plan A 44)," NUREG/CR-3226, May 1983.

7. U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research, " Regulatory Guide 1.155 Station Blackout'" August 1988.

8. Nuclear Management and Resources Council, Inc., " Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at light Water Reactors," NUMARC 87 00, November 1987.

9. Thadani, A. C., letter to W.H. Rasin of NUMARC, " Approval of NUMARC-DocumentsonStationBlackout(TAC 40577)," October 7,1988. j

10. Thadani, A. C., letter with attachment to A. Marion of NUMARC, " Publicly-Noticed Meeting, December 27, 1989," dated January 3, 1990 (confirming "NUMARC 87-00 Supplemental Questions / Answers," December 27,1987). 1 24 i

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

September 1986. I

12. Campbell, T. G., letter to the Document Control Desk of U.S. Nuclear Regulatory Commission, " Arkansas Nuclear One, Unit 1.-Docket No. 50 313, )

Information Submittal for Station Blackout Rule 10CFR50.63,* dated April 1 13, 1989. ,

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13. Fisicaro, J. J., letter N. the document control Desk of U.S. Nuclear Regulatory Commission, " Arkansas Nuclear One - Units 1 & 2, Docket Nos.

50 313 and 50 368, License Nos. DPR-51 and NPF-6, Station Blackout Issue - Supplemental Information," dated July 17, 1990. .

14. Carns, N. S., letter N. the document control Desk of U.S. Nuclear '

Regulatory Commission, " Arkansas Nuclear One - Units 1 & 2 Docket Nos. -

50 313 and 50 368, License Nos. DPR 51 and NPF 6, Station Blackout Issue - Supplemental Information," dated April 3, 1990. ,

15. Arkansas Nuclear One, Unit 1. Updated Final Safety Analysis Report.

16. Rosa, F., Memorandum to Docket Concerning Beaver Valley Units 1 and 2,

Meeting Summary - Meeting of February 22, 1990, on Station Blackout Issues (TAC 68510/68511)," Docket Nos. 50-334 and 50-412, dated March 6, 1990.

17. Tam, P. S., Memorandum for, " Daily Highlight Forthcoming Meeting with NUMARC on Station Blackout (SBO) Issues (TAC 40577)," dated April 25, 1990 (providing a Draft Staff Position Regarding Use of Emergency AC Power Sources (EDGs) as Alternate AC-(AAC) Power Sources, dated April 24,  ;

1990).

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18. Russell, W. T., letter to W. Rasin of NUMARC, ' STATION BLACK 0UT," dated l

June 6, 1990.

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