ML20207D969

Draft Reg Guide 1.155, Station Blackout

ML20207D969
Person / Time
Issue date:	09/14/1987
From:	NRC
To:
Shared Package
ML20195F793	List: ML20195F789 ML20195G040 ML20195G349 ML20207D767 ML20207D778 ML20207D800 ML20207D810 ML20207D969
References
FOIA-87-652, TASK-RE, TASK-SI-501-4 REGGD-01.155, REGGD-1.155, NUDOCS 8808160270
Download: ML20207D969 (43)

Text

_ _ . ___ _ _ ._ __

tOO R4IO(p ENCLOS M E 1

} I. W

' ,a REGULAP.D GU10E I .16 F _

STAT 10h BLACK 0UT_ .

(TASK $1 501-4) ..

A. thiP000CTION Criterion 17.

• Electric Power Systees," of Appendix A. "General Design Criteria for Nuclear Power Plants." to 10 CFR Part 50. "Oomestic Licensing Production and Utilization Facilities " includes a requirement that an onsite

- electric power system and an offsite electric power system.be provided to per- "

sit functioning of structures, systers, and components important to safety.

Paragraph The Commission has amended its regulations in 10 CFR Part 50.

(a) "Requirenie tso' of 650.63. ' Loss of All Alternating Current Powe'r.'

requires that each light-water cooled nuclear power plant be able to wit and recover from a station blackout (i.e.. loss of the offsite electric power system concurrent with reactor trip and unavailability Section 650.63 of the onsite requires that, emergen oc electric power systee) of a specified duration.

for the station blackout duration, the plant be capable of maintaining co It also identifies the factors that ing and appropriate containment integrity.

must be considereds in ' pecifying the station blackout duration.

1 Criterion 18. *laspection and Testing of Electric Power Systees.' of Appendix A to 10 CFR Part 50 includes a requirement for appropriat tasting and inspectb of electric power systems important to safety.

i i

This guide describes a method acceptable to the NRC staff for comply with the Commission regulation that requires This nuclear power plants to guide applies of coping with a staties blackout for a specified duration. _

to all light water-cooled nuclear power plants.

g

$$82pggo08071i SDRCIB7-byg pop l

, Any inforeation collectaon activities related to this regulatory guide are contained as requirements in the revisien of 10 CFR Part 50 that provides the regulatory basis for this guide. The information collection requirements of the revised Fart 50 were approved by the Office of Management aTd Budget approvat number 3150 0011. This clearance applies to any information collection activities related to this guide. ,

8. DISCUSSION 1he term ' station blackout' refers to the complete loss of alternating current electric power to the essential and nonessential switchgear buses in a nuclear power plant. Station blackout therefore involves the loss of off-site power concurrent with turbine trip and failure of the onsite emergency ac power systes, but not the' loss of availaole ac power to buses fed by station batteries through inverters or the loss of power froc

• alternate ac sources."

Station blackojuand alternate ac source are defined in 550.2. Because many safety systees required for reactor core decay heat removal and containment heat removal are dependent on ac power, the consequences of station blackout In the event of a station blackout, the capability to cool could be severe.

the reactor core would be dependent on the availability of systems that do not require ac power from the essential and nonessential switchgear buses and on the ability to restore ac power in a timely manner.

The concern about station blackout arose because of the accumulated Many operating experience regarding the reliability of ac power supplies.

plants have experienced a total loss of offsite electric power, and more In almost every one of these less-occurrences are espected in the future.

of-offsite-pomer events. the onsite emergency at power supplies have been available immediately to supply the pwer needed by vital safety equipment.

However, in same instances, one of the redundant emergency ac power supplies 2

, _ - . . _ _ . _ - _ - _ _ - , _ _ _ _ , , _ , , _ _ . , , . , . . . , .,_,,,,.,,_.,._y._-,,__,_,_y-. _ _--

In a few cases there has been a cornplete loss o' ac hasr been unavailable.

power, but during these events, a: pc,wer was restored in a short time without in adcttien, there have been numerous insta*:es any serious consequences, when emergency diesel generators have failed to start and run in tvsporse to tests conducted at operating plarts. ,

The results of the Reactor Safety Study (Ref.1) showed that, foI one of the two plants evaluated, a station blackout event could be an importatt contrib-utor to the total risk from nuclear power plant accidents. Although t'is total risk was found to be Small, the relative importance of station blackout events This finding ar.d the accumulated diesel generator failure was established.

experience increased the concern about station blackout.

- In a Comission proceeding addressing station blackout, it was determined ,

that the issue should be analyzed to identify preventive or mitigative measures that can or should be taken. (See Florida Power & l.ight Company (St Lucie '

Nuclear Power Plant, Unit No. 2) ALAB-603,12 NRC 30 (1980); modified CLI-81-12, 13 NRC 838 (19fD.)

The issue of station blackout involves the likelihood and duratice of the loss of offsite power, the redundancy and reliability of onsite emergency ac power systems, and the potential for severe accident sequences after a loss of all ac power.

References 2 through 6 provide detailed analyses of these topics.

Based on risk studies performed to date, the results indicate that estimated core melt frequencies from station blackout vary considerably for different In order plants and could be a significar.t risk contributor for some plants.

to reduce this risk, action should be taken to resolve the safety con:ern steeming from station blackout. The issue is of concern for both PWRs and gWRs.

3

(1)r.aintaining This guide primarily addresses the folloaing three areas:

highly r'elistle ac electric power systems. (2) developing procedures and training to restore ef f site and onsite emergency ac power shc.1d either one or both become unavailable, and (3) ensuring that plants can cope with a station black-out for sose period of time based on the probability of occurrence of a station blackout at a site as well as the capability for restoring ac power **

in 'a timely fashion for that site.

One f a:ter that affects ac power systee reliability is the vulnerability to cos Nn cause failures associated with design, operational, and environmental factors. Existing standards and regulatory guides include specific design criteria and guidance on the independence of preferred (offsite) power circuits (see General Design Criterior 17, "Electric Power Systems," and Section 5.1.3

- of Reference 7) and the independence of and limiting interactions between "

diesel generator units at a nuclear station (see General Design Criterion 17 Regulatory Guide 1.6, ' Independence Between Redundant Standby (Onsite) Powe Sources anc netween Their Distribution Systems," Regulatory Guide 1.75, In developing "Physical IMndence of Electric Systems " and Reference 8).

the recospendations in this guide, the staff has assumed that, by adhering to such standards, licensees have minimized, to the extent practical, single point vulnerabilities in design and operation that could result in a loss of all off-site power or all onsite energency ac power.

Onsite emergency ac power system unavailability can be affected by outages resulting f rw testing and maintenance. Typically, this unavailability is about 0.007 (Reference 4) which is small compared to the maximum emergency diesel generator reliability specified in Section C.1.1 of this Regulatory Guide 4

I

- - _ - - _ _._....-_----------.--_.,.___-,-,---.------,._.-..--,-n-,--.-------r----- , . - , . - . . - '

(1.2. , 0.95 or 0.975 reltattlity per demand). However, in some cases outages c've teemaintenance can be a significant contributor to emergency ciesel

• r.is contribution can be kept low by ha <ing high generator unavailability.

quality test and NintenanCt procedures and by scheduling regular.(fesel Also, limiting generator maintenance at times when the reactor is shut down.

conditions for operation in the technical specifications are designed to limit the diesel generator unavailability when the plant is operating. As-long as the unavailability due to test and maintenance is not excessive, the maximum emergency diesel generator failure rates for each diesel generate" specified in Section C.1.1 would result in acceptable overall reliability for the emergency ac power system.

Based on 150.63, all licensees and applicants are required to assess the capability of their plants to maintain adequate core cooling and appropriate '-

containment integrity durir.s a station blackout and to have procedures to cope with such an event. This pide presents a method acceptable to the NRC staff for detemining the specified duration for which a plant should be cble to with-

. stand a station 41ackout is accordance with these requirements. The application of this method results in selecting a minimum acceptable station blackout duration capability from 2 Ro 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> depending on a comparison of the plant's char-acteristics with those factors that have been identified as significantly affecting the risk free station blackout. These factors include redundancy of the onsite emergency ac power system (i.e., the number of diesel generators available for decay heat removal minus the number needed for decay heat I removal), the reliability of onsite emergency ac power sources (e.g., diesel generators), the frequency of loss of offsite power, and the probable time to restort offsite power.

l f

i 5

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

Licensees r.ay propose durations differte.2 from those specified in this guide. .'The basis for alternative durations would be predicated on plant-specific factors relating to the reliability of ac pcwer systems such as those discussec

~

in Reference 2.

Concurrent with the development of this regulatory guide, and 1n consulta- .

tion with the staff, the Nuclear Management anc Resource Council (Nl MARC) de-veloped guidelines and procedures for assessing station blackout coping capabil-ity and duration for light water reactors. The staff has reviewed these guide-lines and analysis methods which are reported in NUMARC-8700, Rev, _, ,

1987 and concludes that this report provides guidance for conforr.ance to 50.63 that is in large part identical to the guidance provided in this regulatory guide.

Table 1_, of this regulatory guide provides a section by section comparison ,

. between RG 1.155 and WUMARC - 8700. The use of NUMARC - 4700 is further dis- ,

cussed in the following Section C, Regulatory Position.

C. REGOLATORY P051 TION

'ed This regulatory guide describes a means accootable to the staff for meeting the requirements of 50.63. EMARC - 8700 also provides guidance acceptable to the staff for meeting these requiresents, with the exceptions noted in Table

,X ,. For these identified exceptions, the guidance in this regulatory guide i should be used.

i 1. ON5 fit EMERGENCY AC POWER 5OURCES (EDG) i 1.1 EDG Target Reliability Levels The minimum EDG reitability should be targeted at 0.95 per demand for each EDG for plants in Emergency AC (EAC) Groups A.B.C and at 0.975 per demand for each EDG for plants in EAC Group D (see Table 1). These reliability levels will be considered etnism target reliabilities and each plant should have an EDG i4 liability program containing the principal elements, or equivalent, as defined in Section 1.2. Plants seiich select a target EDG reliability of 0.W5 stil utilize j the higher level as the target in their EDG reliability programs.

1 i 6 ,

1

The EDG reliability for determining SB0 coping duration vill be determined asfolfows:

(1) Calculate the most recent EDG reliability for eachM based on the last 20, 50 rnd 100 demands using defir.itions and rnethod-oingy ir. section 2 of NSAC-108, The Reliability of Emergency

-- Generators at US Nuclear Power Plants (Septeeter 1985T'or equivplent.*

(2) Calculate the nuclear unit "average" EDG reliahlity for the last 20,50 and 100 demanos by averaging the results from step (1)1bove.

. (3) Compare the calculated "average" nuclear unit EDG reliability ,

from step 2 above against the following criteeia:

Last 20 demands 0.90 reliability

1. Last 50 demands 0.94 reliability Last 100 demands 0.95 reliability (4) If the EAC group is A,B,C AND any of the three evaluation

- criterin in step 3 are met, then the nuclear enit may select an ED6 reliability target of either 0.95 or C.975 for deter-mining the applicable coping duration froe Table 1. If the eat group is D, and any of the three evaluation criteria in step 3 are set, then the allowed EDG reliability target is 0.975.

(5) If. for EAC groups A,B and C NONE of the selection criteria in Step 3 are met, then an EDG reliability level of 0.95 aust be l

utilized for determining the applicable coping duration frorr h

l *This EDG reliability is not suitable for PRA(s) for design basis accidents because of the differing EDG start reliability requirement that would be applicable for such PRAfs).

I l

7

Table 1. If the "averaged" nuclear unit EOG reliability is als:

less than 0.90 based on the last 20 demands then acceptability ef a coping duration based on using an EDG reliability of 0.95 from Table 1 must be further justified.

. 1 If the EAC group is D and none of the three evaluation,, criteria

- in step 3 are met, the resulting required coping duration (See ]

Table 1) resulting from step 3 will be increased to the next l highest coping level (i.e. , 4-hours become B-hours, 8-hours becomes 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />).

1.2 Reliability Program The reliable operation of on-site emergency AC power sources should be ,.

ensured by a reliability program designed to maintain and monitor the reliability level of each power source over time for assurance that the selected reliability levels are beigac'r sved. An EDG reliability program would typically be comprised of the following elements or activities (or equivalant):

(1) Establishment of individual EDG reliability target levels con-sistent with the plant category and coping duration selected froc Table 1.

(2) Surveillance testing and reliability xnitoring programs desi5ned to track EDG performance and also support maintenance activities.

(3) A maintenance program which ensures that the target EDG relicil-ity is being achieved and which also provides a capability for failure analysis and root cause investigations.

(4) An information and data collection system capability which services the elements of the reliability program and which asaltors achieved EDG reliability levels against target values.

8

(5)

Identifid responsibilities for the major program elements an: a management oversight program for re.tewing reliability j

leiels being achieved and assuring that tr.e program is '

futctioning properly.

Procede es for Restoring Emergency AC Power 1.3 hutdelines and procedures for actions to restore emergency ac power when the emergenc,. ac power system is unavailable should be integrated with plant-specific te:hnical guidelines and emergency operating procedures developed using the emergen:y operating procedure upgrade program established o in response "tar to Supplement 1, ' Requirements for Emergency Response Capability" (Gener go,3233), to NJREG-0737, "Clarification of TMI Actiot Plan Requirements .

2. OFFSITE POWER  !

Proced$res should include the actions necessary to restore offsite

• • s when offsite power is unavailable. As a power and use nearby power sources minimum, the following potential causes for loss of offsite power should be cormidered:

' Grid undervoltage and collapse. )

• Weather induced power loss.

I

• Preferred power distribution system faults 8 that could result in the l

i loss of normal power to essential switchgear kses.

I Modifications or additions to generic technical guidelines that are necessary

@ deal with a station blackout for the specific plant design should be identified as deviations in the plant-specific technical guidelines as required by Supplement 1

1 to NUREG-0737 and outlined in NUREG-0899. "Guidelines for the Preparation of l

Emergency Operating Procedures."

e This includes such items as nearby or onsite gas turbine generatcrs, portable l

l generators, hydro generators, and black-start fossil power plants.

s Includes such failures as the distribution system harthsare, switching and i

maintenance errors, and lightning-induced faults. ,,

l l

9 l 1

3. ABILITY TO C0_f . WITH A STa?!ON BLACK 0UT

,a The ability to cope with a station blackout for a certain time ;-: ides additional defense-in-depth should bcth offsite and onsite energenty ac p:wer syster.s fail concurrently. Sectior C.3.1 provides a method to determine ar. ,

acceptable minimum time that a plett should be able to cope with a statice blackout based on the probability cf a station blackout at the site as we!1 as the capability for restoring ac power for that site. Each nuclear power plant has the capability to remove decay heat without ac power for a lirited pe fod of tis 4. Section C.3.2 provides pid.ance for determining the length of time If the plant's that a plant is actually able to ccpe with a st6 tion blackout.

actual station blackout capability is significantly less than the acceptable minimum duration, modifications may be necessary to extend the plant's ability to cope with a station blackout. Should plant modifications be necessary, ,

Section C.3.3 provides guidance on making such modifications. Whether or not modifications are necessary, procedures and training for station blackout events should, be provided according to the guidance in Section C.3.4.

ed 3.1 Minimum Acceptable Station Blackout Duration Capability Each nuclear power plant should be able to withstand and recover from a station blackout lasting a specified minimum duration. The specified duration of station blackout should be based on the following factors.

a. The redundancy of the oesite urgency ac power systeo (i.e., the I

l number of power sources available minus the number needed for decay l

i heatremoval),

1 1

I b. The reliability of each of the onsite emergency ac power sources (e.g., diesel generator),

1 l

10 l_ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ - _ _ - . _

, c. Tre espected frequency of loss of offsite power, and

d. 1 probable time needed to restore offsite power.

A method for determining an acceptable minimum station bIackout duration capbility as a function of the above site- and plant-related char-acteristics is given in Table 1. Tables 2 through 7 provide the necessary

• detailed des 1:riptions and definitions of the various factors used in Table 1.

Table 2 identifies different levels of redundancy of the onsite emergency ac power syste: used to define the emergency ac power configuration groups in Table 1. Table 3 provides definitions of the three offsite power design char-acteristi . grcops used in Table 1. The groups are defined according to various combinations of the following factors: (1) independence of offsite power (1),

(2) severe weather (SW), (3) severe weather recovery (SWR), and (4) extremely ~

~

severe weather (ESW). The definitions of the factors 1, 59, SWR, and ESW are provided in Table 4 through 7. respectively. After identifying the appropriate groups from Tables 2 and 3 and the reliability level of the onsite amergency ac power sourcAh.(determined in accordance with Section C.I.1 of this regula-tory guide), Table 1 can be used to deterinine the acceptable minimum station blackout dvration capability for each plant.

3.2 Evaluation of Plant-Specific Station Blackout Capability Each nuclear power plant should be eyeluated to determine its capability to withstand and recover from a station blackout of the acceptable duration detemined for that plant in Section C.3.1. The following considera-tions should be included when determining the plant's capability to cope with a station blackout:

3.2.1. The evaluation should be performed assuming that the plant is operating at full power issediately before the postulated station blackout.

11

3.2.2 , The capability of all systems and components necessary to Vo.ide core cooling and decay heat removal following a station blackout should be deterrined, ir,cluding station battery capacity, condensate storage tank capacity, ccepressed air capacity, and instrumentation and control requirements.

- I The ability to maintain adequate reactor coolant system inter. tory to l 3.2.3. '

ensure that the core is cooled should be evaluated taking into consiceration shrinkage, leakage from pump seals, and inventory loss from letdown er other nonnally open lines dependent on ac power for isolation.

3.2.4. The design adequacy and capability of equipment needed to cope with station blackout should be addressed and evaluated as appropriate for the er.viron-sen..a1 conditions associated with a station blackout for the require: dura'. ion

~

~

and recovery period. This should include, consideration as appropriate of the following:

1. potegijal failures o' equipment necessary to cope with station blackout

2. potential environmental effects on the operability and reliability of equipment necessary to cope with station blackout

3. potential effects of other hazards, such as weather, on station black-out response equipment (e.g., auxiliary equipment to operate on site buses or to recover EDGs and other equipment as needed).

4. potential habitability concerns for those areas which would require operator access during the station blackout and recovery period.

Evaluations that have already been pt;rrormed need hot be tplicated.

! For example, if safets related equipment requirt! during a total loss of ac power

! has been qualified to operate under environmenul conditions exceeding those ex-pected under a station blackout (e.g., loss of heating, ventilation and air conditioning) addittomal analyses need not be perfonned. Equipment irill be con-sidered qualified for station blackout temperature environments if an assessment has been perfomed that provides reasonable assurance that the required equipment will remain operable.

12 t

\

d

?,$.5.' Consideration should be giver to using available non-safety-relate:

f aq.,ipment, as well as safety-related ewipment, to cope with a station blac6:.

i C.3.3.3 and C.2.3.4

.provided such equipment meets the recoesnendations of Sect ons Onsite or nearby alternate at (MC) power sources of this regulatory guide.

trat are independent and diverse from the nonnal Class 1E emergency ac power sources (e.g., gas turbine, separate diesel engine, steam supplies) w.ill -

constitute an acceptable station blackout coping capability provided an analysis is performed that demonstrates the plant has this capability from the onset cf station blackout until the MC power source (s) is started and lined up to operate all equtpeent necessary to cope with station blackout for the required plant dura tic-In general, equipment required to cope with a station blackout during -

For equipment not located or the first 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> should be available on site.

site, consideration should be given to its availability and accessibility ir. the time required, including consideration of weather conditions likely to prevaf t during a loss Akoffsite power.

If the Mt source (s) meets the above requirements and can be demon-strated by test to be available within 10 minutes of the onset of station blackout then no coping analysis is required.

3.2.6. Consideration should be given to timely operator actions inside o-outside the control room that would increase the length of time that the plant can cope with a station blachut provided it can be demonstrated that these l For example, if station battery actions can be carried out in a timely f ashion.

capacity is a limiting tactor in coping with a station blackout, shedding non-essential loads on the batteries could extend the time until the battery is 6epleted. If load shedding or other operator actions are considered, r.orrespond-

' ing procedures should be incorporated into the plant-specific technical guide-lines and emergency opersting procedures.

The ability ts maintain ' Appropriate Containment Integrity" should be 3.2.7 addressed. "?gpropriate Containment Integrity" for station blackoutis defined such that adequate cantalament integrity is ensured by providing AC independent

}

I i

13

3.5.5.' Consideration should be giver to using available non-safety-relate:

eq.ipment, as wt:11 as safety-related equipment, to cope with a station black:a provided such equipment meets the recosenendations of Sections C.3.3.3 and C.2.3.4 of this regulatory guide. Onsite or nearby alternate ac (AAC) power sources trat are independent and diverse from the nonnal Class 1E emergency ac power sources (e.g., gas turbine, separate diesel ugine, steam supplies) will -

constitute an acceptable station blackout coping capability provided an analysis is perfonned that demonstrates the plant has this capability from the onset cf station blackout until the AAC power source (s) is started and lined up to operate all equipcent necessary to cope with station blackout for the required plant du ra tion.

In general, equipment required to cope with a station blackout during For equipment not located or the first 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> should be available on site.

site, consideratien should be given to its availability and accessibility ir. the time required, including consideration of weather conditions likely to prevail during a loss AI5offsite power.

If the AAC source (s) meets the above requirements and can be demon-strated by test to be available within 10 minutes of the onset of station blackout then no coping analysis is required.

( .

l 3.2.6. Consideration skuld be given to timely operator actions inside o-outside the control room that would increase the length of time that the plant

! can cope with a station blackout provided it can be demonstrated that these For example, if station battery actions can be carried out in a timely fashion.

capacity is a limiting factor in coping with a station blackout, shedding non-essential loads on the batteries could extend the time until the battery is depleted. If load shedding or other operator actions are considered, correspond-ing procedures should be incorporated into the plant specific technical guide-lines and emergency opersting procedures, The ability to maintain ' Appropriate Containment Integrity" should be 3.2.7

• addressed, "Appropriate btainment Integrity" for station blackout'is defined such that adequate costajament integrity is ensured by providing AC 'indepesdent l

i i 1 13  !

1

P capabili,ty for indicatic.r of valve position and AC independent capability of closure for contairment iselation valves identified in technica* specifications which may be in the open position at the onset of a station bla:kout. The follow.

ing valves are excluded fror. consideration:

(1) valves nomally locked closed during operation .,

(2) valves which fail closed on a loss of power (3) check valves (4) valves in non-radioactive closed-loop systems not expected to be breached in a station blackout (this does not include lines which comunicate directly with containment 1stmosphere) ~

(5) valves of less than 3" nominal diameter.

'4 i

I e.

14 l

3 .,2 Modificatiors to Cope with Statice Blackout

f the plant's station blackout capability, as detennined according to the gu

ance in Section C.3.2 of this regulatory guide, is significantly less than the n'nimum acceptable plant-specific station blackout duration as developed ac::-ting to Section C.3.1 of this regulatory guide (or as justified by' the li:rsee or ipplicant on some other basis ar.o accepted by the staff),"modifi-cati:ms to the plant may be necessary to extend the time the plant is able to co;e with a station blackout. If mooifications are needed, the following itses should be considered:

3.2.1. If, after considering load shedding to extend the time until bettery de;'etion, battery capacity must be extended further to meet the station blacko.t

- &ntion recos ended in Section C.3.1 of tMs regulatory guide, it is considerec ~

ac:ertable either to add batteries or to add a charging system for the existing batteries that is independent of both the offsite and onsite emergency ac power systems such as a dedicated diesel generator.

n*

3.3.2 If the capacity of the condensate storage tank is not sufficient to rencve decay heat for the station blackout duration recossnended in Section C.3.1.

of tJhis regulatory guide, a system to resupply the tank from an alternative wate- source is an acceptable means to increase its capacity provided any power scurce necessary to provide additional water is independent of both the offsite ard the onsite amergency ac power systems.

3.3 .3 If a systes is required for primary coolant charging and makeup, reactor coolant pump seal cooling or injection, or decay heat removal specifically to meet the station blackout duration recomunended in Section C.3.1 of this regulatory guide, the following criteria should be met:

a. The system should be capable of being actuated and l

I controlled from the control room, or if other means of control are required, it should be demonstrated that these steps can be carried out in a timely _

fashion; and 15 l -_ - - _- .

- b. If the system must operate within 10 minutes of a loss of all ac power, it should be capable of being actuated i I

from the control room.

l 3.3.4 If an alternate ac (AAC) power source is selected specifically for satisfyir; the requirements for station blackout, the design should syet the following criteria;

4. The AAC power source should not normally be directly connected to the preferred or onsite emergency ac power system.

t

b. There should be a minimum potential for comon cause failure with the preferred or the onsite etr.ergency ac power sources. l Nu single point vulnerability should exist whereby a weather related event or single active failure could disable any

.j portion of the onsite emergency ac power sources or the pre-  :

ferred power sources, and simultaneously fail the AAC power source (s).

c. The AAC power source should be available in a timely manner after the onset of station blackout and have provisions to be manually connected to one or all buses as required of the redundant safety buses. The time required for making this equipment available should not be more than one hour as demonstrated by test.

d. The AAC power source should have sufficient capacity for operation of the systems necessary for coping with station blackout for the time required to bring and main- ,

tain the plant in safe shutdown.

16

e. The AAC power system should be inspected, maintained and testet periodicelly to demonstrate operability and reliability. Te reliability of the AAC power system should meet or exceed H percent as deterinined in accordance with NSAC-108 methodolva (orequivalent).

An- AAC power source (s) serving a multiple unit site where onsite emer-9ency ac source (s) are not shared between units should have, as a minimum, the capacity and capability for coping with station blackout in any of the units.

At sites where onsite emergency sources are shared between units, the AAC power source (s) should have the capacity and capability as required te assure that all units can be brought to and maintained in safe shutdown (hot shutdown or hot standby as appropriate).

Plants which have more than the required redundancy of emergency ac source (s) for ps of offsite power conditions, on a per nuclear unit basis, may use one of the existing emergency sources as an AAC power source provided it meets the above applicable requirements for an AAC source.

3.3.5 If a system or component is added specifically to meet the reconnen-dations on station blackout duration in Section C.3.1 of this regulatory guide, system walk downs and initial tests of new or modified systems or critica components should be performed to verify that the modifications were performed properly. Failures of added components that may be vulnerable to internal or external hazards within the design basis (e.g., seismic events) should net result in secondary failures causing a loss of emergency ac power systems c.

a loss of other safety-related equipment.

3.3.6 A system or component added specifically to meet the recommendations on station blackout duration in Section C.3.1 of this regulatory guide should be inspected, saintained and tested periodically to demonstrate equipment operability and reliability. .

17

3 . 4'

' Processres and Training to Cope with Statior Blackou_t Procedures and training should include all operator actions necessary to cope with a station blackout for at least the duratio* determined according to section C 3.1 of this regulatory guide, and to restort norw.s1 long-ters. core cooling / decay beat removal once ac power is restored.

3.5 Quality Assurance And Specification Guidance For Station Blacnut Equipment That Is hot Safety-Related Appendices A and B provide the guidance for quality assurance (QA) activities and specifications respectively for non-safety related equipment for which credit is taken in the resolution of Station Blackout (Generic Issue A.44). Appropriate activities shall be implemented from aeong those listed in ,

these appendices depending on whether the non-safety equipment is being added (new) or is existing. This QA guidance is applicable to non-safety systems and equipment for, meeting the requirements of 10 CFR 50.63. The guidance on QA and specification ifcorporates the lesser degree of stringency by eliminating requirements for involvement of parties outside the mornal line organization and requirements for a formalized program and detailed recordkeeping for all NRC inspections quality practices as required for safety-related equipment.

will focus on the implementation and effectiveness of the quality controls Additionally, the whose attributes are described in the appendices A and B.

equipment installed to meet the station blackeet rule umst be implemented such that it does not degrade the existing safety related systems.

This is to be accomplished by making the non-safety related equipment independent to the l If the non safety sys-extent practicable from existing safety related systems.

tems identified in appendix 5 are utilized for responding to a station blackout, the guidance provided in appendix 8 is acceptable tc the staff for those systems.

0 Frocedures should be integrated with plant-specific technical guidelines f and emergescy operattag procedures developed using the emergency operating l

procedure upgrade program established in response to Supplement 1 of WREG-0737. The task analysis portion of the energency operating procedure I upgrade program should include an analysis of instrumentation adequacy during a station blackout.

18

D. IMPLEMENTAT10N The purpose of this sectier. is to provide information to appi1ce ts and licensees regarding the NRC staff's plans for using this regulatory paide.

Except in those cases in which the applicant or licensee proposes an accept-able alternative rethods for cor. plying with specified portions of the Cour.ission's regulations, the method described in this guide will be used in the esaluation of submittals by applicants for construction permits and operating li:enses and The by licensees who are required te comply with 650.63, "Station Blackot*.*

rule requires that the submittel be a FSAR amen &wnt. It is expecte: that a licensee or an applicant will have available for review, as required, the analyses and related inforration that supports the submittal.

m 19

~ -- _ _

Table 1 Acceptable Station Blackout Duratio Capability (hours b

Emergency A* Power Configuration Group

- A B C D Unit %erage" EDG Reliability Of f site Power Design e

Characteristic Group 0.975 0.95 0.975 0.95 0.075 0.95 0.975 2 2 4 4 4 4 4 P1 4 4 4 4 4 8 8 P2 4 8 4 8 8 16 8 P3 a Variations from these times will be considered by the staff if justification, including a, cost-benefit analysis, is provided by the licensee. The methodol-ogy and sensitivity studies prasented in NUREG-1032 (Ref. 2) are acceptable for use in this justification.

bSee Table 2 to determine energency ac power configuration group.

'See Table 3 to determine groups P1, P2, and 73.

l l ..

1 1

20 l

Table 2 Emergen:y AC Power Configuration Groups' k.cergfEACPower Number of EAC Po.e* Sources Emergency AC (EAC) Required to Operate AC-Powgred Power Configuration 5:urces Decay Heat Rem:.a' Systems Group

• d 3

'. 3 A 1 4

4 2 .

l 3 2 5

1 C 14 2l 3 1 1

2 0 2 3 l

~ 3 4

3 5

a Special purpose dedicated diesel generators, such as those associated with l high pressure core spray systems at some SWRs, are not counte: in the determination of EAC power configuration groups.

b]f any of the EAC power sources are shared among un site.

"This number is based on all the ac loads required to remove decay heat (includi AC powered decay heat removal systems) to achieve and maintain hot shutdow all units at the site with offsite power unavattable,

• l d for EAC power sources not shared with other units. l I

'For EAC power sources shared with another unit at a multi-unit site.

l l I For shared EAC power sources in which each' diesel generator is capable of pr) widing ac power to mort than one unit at a site concurrently.

21

9. Zi- 6 7 yg S Ay'9tt TAGL t X .

CROSS REFERENCE OF STATION 8 ACKOUT R.G. 1.155 TO NUMARC !?:0 R.G. SECTION 0 NUMARC 8700 1.1 3.2.3, 3.2.4 1.2 Appendix 0 1.3 4.2.1, 4.3.1 2 4.2.2, 4.3.2 3.1 3 3.2.1 2.2.1. 2.2.2 ' '

3.2.2 7.2.1, 7.2.2, 7.2.3, 2.9 .

3.2.3 2.5 3.2.4 2.7, 7.2.4, Appendix E '

\

3.2.5 - ,

3.3.3,7.1.1,7.1.2, Appendix) -

3.2.6 4.2.1, 4.3.1, 7.2.1, 7.2.2, 7.2.3 3.2.7 7.2.5 3.3.1 7.2.2 3.3.2 - -

7.2.1 3,3,3 No ref erence . r %-

3.3.4 2.3.1, Appendix A, Appendix B 3.3.5 No reference '.

l 3.3.6 4.2.1(12) . 4.3.1(12),3.3.3, 4o0. A and 9 3.4 4 l 3.5 No reference .

1L/= A tA ,

,.hv% *

'R.c,

// .

f

., -.-n,.---...,,n--,----..--,--, - - - _ , - - , - , _ - , , , - - - _ , , . , . _ . , , , , , - . - _ , . . . . . , , - . - , - , ,.,-,-,,-,,.---.,-.,,n-. - , , _

s i

a >

Table 3 Of' site Power Design Characteristic Gros;s ,

Group Of fsite Power Design Chara:te istics -

Sites that have any combination of the fc11owing f actors:

8 D C d 1 SW SWR E5W F1 1 er 2 1 or 2 1 or 2 1 or 2 1 er 2 1 1 or 2 3 1 cr 2 3 1 1 or 2 P2 All other sites not in P1 or P3.

Sites that expect to experience a tota'. loss of offsite power caused by grid failures at a frecuency equal to or greater than once in 20 site years, unless the site has j procedures to recover ac power from reliable alternative (nonemergency) ac power sources within approximately one-half hour following a grid f ailure.

E Sites that have any combination of the following factors:

P3 1 SW SWR ESW Any I 5 2 Any ESW

! Any 1 1,2,3, or 4 1 or 2 5

Any 1 5 1 Any ESW Any 1 4 2 1.2.3 or 4 t 1 cr 2 3 2 4 l

3 3 2 3 or 4 l

a Ste Tatie 4 for definitions of independence of offsite power groups (1).

bSee Table 5 for definitions of severe weather groups (SW).

c See Table 6 for definitions of severe wather recovery grows (SWR).

dSee Table 7 for definitions of extremely severe weather groups (ESW).

I 1

l l

22 l

4 1

h. e .

t ' 9 eft ltless of ledepeedseco of Offsit2 Pouve Geeses. 1

~

3 2 -

I C^ 1 _

l -,y .-

• f All offstte peser soortes are c; -ccted to IP.e plant through .

I e^^ i ce of offstte j All efecte fs.tte.eponer seerces are ene _ltc,i,.rd.

t~ ...at t-eeg er s ,r .es.ces .

J c

two or more teltchyards er seperate I

.

• laceslag transelssion Ifnes, but et All ef felte poner seertes are cessietted to 19ee plaat through toe teest one of the oc seertes is oc more settchy.res, sad the sultchyards er, electrically connected. e eerstetest oy sna.,e.arat of the ethers. (The ladependent 69-tV (the 345- and tie tv settchteres la f lueve i reweeseat tht eess .

Ilsie la fIgore 1 la repessestative festore.)

ef this design feetwee.)

l and _and E -

If tle novne.' soorte of oc poser After less of the esemet oc power f alls, there we no eetematte l

f Iffalls, the mecast seerte of oc posee there is am setenstic seerte, there is one setematic transfer. If this searce falls, temasters and sne er more meneet transfer to e preferred seerte of transfers to parterred ee alteraete If this preferred seerte there mer be one oc more manue1 stestte peser v=rces. (normally le and esesel transfee power. trassfers of peser seertes to apen (se), menectly operated of posee falls, there is an ==te- perferred or alterstate offsite lieses for the fless at teses mette transfee to anothee source of etr<lts to the C ass It beses as tlie normel seerte of ac poner posee sources. (The meneet shown in fleere 3 ere representative

} offsite power. (The transfer free transfer from the sete-treasfeeser Fgilt and efien the bettee searces of this design featwee.)

Of effelte posee fell the 161-tv mete-transformer to the to Lfte 69-tv seerte in Ftgere 1 la l

Es-tv searce in Ffgere 1 is repre- representattwe of this design j sentative of this design festere.) festere encept theatransfer from i

' - the aute-transteener to the 61-sV seerte new1d be mensel. )

1, or i

I If sne me e1 see m of oc pow e if.the

f. .s mornei m,e is seerte of c y = r e.e .et-tic f.lis. t,.ere is one este.et.c transfer bet no memsat treastees l trasester het no espoet treasfers to to peeferred or atternete offstte preferred er alternate offstte power searces.

' poser seseces.

s I

19ee Class It hoses la a emit see Att of the Class It boses la e unit 1 are connected to the gamme preferred connected to seperate of fsite power peser seerte ef ter 184 estomatic l sources after the setemat6c i transfer of power searces. (ffte treasfer of power seerces. (the i  ? . transfer to the two 138-4V Seltett- ,treaster of the Class It treses from one preferred toesrce to another l yard seertes in Figere 2 le repre- preferred searce la Figere ) ts j sentative of this design feature.) eeerescatative of this design if j

the transfer were automatic tastead l j et manual.)

I s

i I

i

' - Tatte 5 Definitions of Severe Weather Groups (SW)

Estimated frequenjy of loss of of fsite power d'ue SW Group severe weather, f (per site year) ,

I .

f < 0.003S .

2 0.0033< f < 0. 010 3 0.010 7 f < 0.035 4 0.03){f<0.10 <f 5 0.10 aire estin.ated frequency of loss of offsite power due to severe weather, f, is determined by the following equation:

f = (1.3 x 10~4)hg + (b)h2 + (0.012)h3 + (c)h4

. ~

^

where b y = annual expectation of snowf all for the site, in inches, h2 = annual expectation of tornadoes (with wind speeds greater than or equal to 113 miles per hour) per square sile at the site, bD2.5 for sites with transmission lines on two or more rights-of-way spreading out in different directions from the switchyard if separated by at least 1/4 mile at distances > I mile from ,,

the site switchyard, or b = 72.3 for sites with transmission lir.es on one right-of-way.

h annual expectation of stores at the site with wind velocities 3 = between 75 and 124 aph, and h4 = annual expectation of hurricanes at the site c = 0 if switchyard is not vulnerable to the effects of salt spray c = 0.78 if switchyard js vulnerable to the of fects of salt sp ay The annual expectation af snowf all, tornadoes, and stores say be obtained from National Weather Service data from the weather station nearest to the plant The cr by interpolation, if appropriate, between nearby weather stations.

basis for the empirical equation for tt,e frequency of loss of offsite power due to severe weather, f, is given in Appendix A to Reference 2.

i i

s 24 l

l l

1

Table 6

~

De'initions of Severe Weather Recovery Groups (SWR)

• . 6=

SWR Grov: Definition j .

1 Sites with enhanced recovery (i.e., sites that have the capability and procedures for restoring offsite (non-emergency) ac power to the site within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />

~

following a loss of offsite power due to severe ,,

weather.)

4 2

Sites without enhanced recovery.

G .

25

l

' - Table 7 Definitions of Extrer41y Severe Weather Groups (ESW)

Annual expectation of storms at a site with wind velocities ec;al to or greater than 125 miles .

E5W Group

• per hour (e)

e < 3.) 10

~3 2 3.3 x 10 i e < 1 x 10 l

~3 ~3  ;

1 1 x 10 1 e (3,3 x 10  !

I

~3 -2 . ,

l 3.3 x 10 i e < 1 x 10 l

\

-2  ;

5 1 x 10 i, i

• Wind speeds excess of 125 siles per hour are predominantly associated with hurricanes.

Plant sites with hurricane response procedures that place the unit into safe shutdown conditions 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> prior to the expecte LOOP caused by an approaching hurricane may use the next lowest ESW grow.

• • The annual expectation of storas may be obtained from National Weat".er Service data from the wea?.her station nearest to the plant, or by interpolation, if appropriate, between nearby weather stations.

I 1

l l

l -

26 l

f

i .

i i

1 l

l ..

1 I '

d b b b 69kV j h I 161 kV I l  :  :

I i :pt kV l

.  ; l .. - -.

j ,

l l l

' 1

[

AWvm V

! w .

I l

i I .... . . .

y,w N M  ;

1 l ANW#M 'M"y' y AUTOMATIC Mg My i MMMM .T.RANSFEA.*

l

-- +

l gim _AUToMA

_ - TIC 1[ 1[

i GENERATOR qI 1I if 1[

TR ANST E R

! Ne NC NO

, NC epss ,, woNsAF Tv cLAs$tg NONsAF ETY l

i 4 '

i t. AutoM

- AT.I.C T R ANSF E R----,-

! )

l Au.TO.W. A.T.IC TR ANSF E R- ---,,)

l L

I n y re 1. Schematic diagram of electrically independent transmission line . . ..

e l

r 27

- - + - , -..-,--.,..m - -

..,,-_,_,__,,__,y, ,, _

W e e l'

• l l , l > 4 ,

t l >

L i, l,

) , __

m l g_

j r 4 tas av Y

i

' h E l [

\

l N W

~

( l EM MM nw ww I I

H asok&Af t1Y NO y r'e*aAftty too CLASS 11 set WC . ctAts 1g Divil:0N2 CLAIS Sg CHviliCN 1 esa:N CLA&&18 SINIRA10A Dvtl:0N 1 Wy@0ne 2 4 i &

e ' >

l L..tce n un.~m.. 4........ -

l t . . . . _v,=a'nu.=.:Es . . s . _ .;

I Figure 2. khanatic diagram of two switchyards I

electrically connected (one unit site) i .

l I

l 28 i

. . 1 j

,e I

l

.L h ,

r l l 230 kV ,

Sco av .

I 4

MM I i 1

MM M M MM MM MMM M MMMM il if If If If If If If etNERATOR 2 NC 70 Ne10 WC TO NC NC GENER ATOR t he NC WC 70 8083 80"I 8081 8081 NONEA8 TTY peo esArtTY UNIT 2 UNIT 1 UNIT 1 UNif 1 UN113 UNIT 2 CLASS 11 CLA1118 CLA15 s, If CLA5515 9Ultl. SMts, Sult custs.

NO TO NO TO N010 WO 10 OTHtR$ OTHERS OTHERs OTHER$

Figure 3. Schematic diagram of two switchyards electrically conTected (two-unit site)

So 29 s.

O

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ . . _ _ _ . ._,.--,. , .- , __ -m . . . , _ _ . . _ _ , , - _ _ . . , , . . , _ . . . . . - . . _ . . . _ , , _ _ . _ __ _ _ , . ,

REFERENCES

1. U.S. Nuclear Regulatory Comission, "Reactor Safety Stucy,' 40(5H-1400, October 1975.

2. U.S. Nuclear Regulatory Comission "Evaluation of Station Blackout Acci-dents at Nuclear Power Plants. Technical Findings Related to Unresolved Safety Issue A-44,' NUREG-1032, September,1987.

3. U.S. Nuclear Regulatory Comission, ' Collection and Eva'uation of Complete and Partial Losses of Offsite Power at Nuclear Power Plants," NUREG/CR-3992, February 1985.

4. U.S. Nuclear Regulatory Comission "Reliability of Eme gency ac Power Sources at Nuclear Power Plants," NUREG/CR-2989, July 1383.

A

5. U.S. Nuclear Regulatory Comission "Emergency Diesel Generator Operating Esperience, 1981-1983." NUREG/CR-4347 Decenter 1985.

6. U.S. Nuclear Regulatory Comission "Station Blackout Accident Analyses (Part of MRC Test Action Plan A-44) " WUREG/CR-3226, May 1983.

7. Institute of Electrical and Electronics Engineers, 'IEEE Standard for Preferred Power Supply for Nuclear Power Generating Stations," IEEE Std 765-1983.*

8. Institute of Electrical and Electronics Engineers, "IEEE Standard Criteria for Diesel Generator Units Applied as Standby Power Supplies for Nuclear Power Generating Stations," IEEE Sta 387-1984.*

9. Electric Power nesearch Institute "The Reliability of Emer9ency Diesel Generators at U. f. Nuclear Power Plants" NSAC-106, September 1986.

10. N O K W - % 180, h [

' Copies may be obtained from the Institute of Electrical aid Electronics v. , p^* --

Engineers, 345 E. 47th Street, New York, NY 10017.

'f'f)

%Itg 30

l VALUE/IP.;ACT STATEMENT A separate value/ impact stateeent was not prepared for this regulatory guide. The regulatory analysis prepared for the station blackoJt rule (NUREG-1109) provides the regulatory basis for this guide and examines the costs and benefits of the rule as implemented by the guide. A copy of MUREG-1109 is available for inspectier. and copying for a fee at the NRC Public Document Room,1717 H Street NW. , Washington, DC 20555. Free single l

ecpies may be obtained upon written request to the Distribution Section, Rcom  !

P-1304, Division of Information Support Services U.S. Nuclear Regulatory Commission, Washington, DC 20555.

• hY t

e.

t 31

4 Appendix A Quality Assvance Guidance for Non-Safety Systems tad Equipment

3. General ~

This sectior provides the guidsnce for quality assurance (QA) activities for non-safety systems and equipment for which credit is taken in the

^

resolution of Station Blackout (USI A-44) and for which there ar'e no existing NRC QA requirements (e.g., Appendix 8. Ap;endix R). Activities l

j shall be it;lemented from among those listed in this section as l

appropriate, depending on whether the equipment is being added (NEW) or is existing.

The QA guidance provided herein explicitly is required for non-safety systems'and equipment used to meet the requirements of 10 CFR 50.63 and ,,

not already covered by existing 10 CFR QA requirements. This guidance is not intended to require the formalized program or detailed record keeping as required for safety-related equipment. Additionally, non-safety equipmentYnstalled to meet the station blackout rule must be implemented such that it does not degrade the existing safety-related systems. This is accomplished by making the non-safety equipment independent to the extent practical from existing safety-related systems. The guidance provided in this section outlines an acceptable QA program for non-safety equipment used for meeting the station blackout rule and not already covered by existing 10 CFR QA requirements.

32 i

e

---,em---.-- --

-,,+-,,--,--.------_,--.,---.,,,,,,,_,,,_n,.--__-e, n,-,,,, ---ne,-, - -,

Appendix A (Cont'd)

2. (A Guidance for Non-Safety Equi;eent Not Covered By Other 10 CFR QA Requirements (1) [;* sign Control and Proegunt Document Control .,

keasures should be established to ensure that all design-related guidelines used in complying with 10 CFR 50.63 are included in design and procurement docunents and that deviations therefror are controlled.

(2) Instructions, Procedures and Drawings Inspections, tests, administrative controls and training necessary for compliance with 10 CFR 50.63 requirements should be prescribed

- by . documented instructions, procedures and drawings and shoule be accomplished in accordance with these documents.

(3) Centrol of Purchased Material. Equipment and Services Measures should be established to assure that purchased material, equipment and services confom to the procurement documents.

(4) Inspection A program for independent inspection of activities required ts comply with 10 CFR 50.63 should be established and executed by or for, the organization performing the activity to verify confomance with documented installation drawings and test procedures for

ccomplishing the activities.

33

.,.,-.-.e s ,..-,,.,----,----.---a~

7..-.

Appendix A (Cont'd)

(5; Test and Test Control A test program should be established and implemenled to assure that testing is perfonned and verified by inspection and audit to demonstrate conformance with design and system readiness requirements.

The tests should be perfomed in accordance with written test procedures; test results should be properly evaluated and acted on.

(6)

Inspection. Test and Operatino Status

~

heasures should be established to provide for the identification of ,

items that have satisfactorily passed required tests and inspections.

(7) Nor.Nnforminoitems Measures should be established to control items that do not conforin to specified requirements to prevent inadvertent use or installation.

(8) Corrective Action Measures should be established to assure that conditions such as failures, malfunctions, deficiencies, deviations, defective components, and non-confonnances are promptly identified, reported and corrected.

(9) Records f

Records should be prepared and maintained to furnish evidence that the criteria enumerated above are being met for activittee required to comply with 10 CFR 50.63.

1 34

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

B Appeadim A (Cont'd)

(10) Audits Audits should be conducted and documented to verify comf'tance with design and procurement documents, instructions; procedures an'd dnwings; and inspection and test activities developed t (amply with 10 CFR 50.63.

e Pe I

J5

I Appendix 8 Guidance Regarding System and Station Equipment Specifications Altemate Battery System (s)

Systems: Alte m te AC Source (s) g Guidance:

i Not Required, but the implementation Safety Related 99et Rogstred. but, the implementation must be sust be such that the existing class i IEEE-279 such that the existing class IE electrical 1E battery systems continue to meet

}

systems continue to meet all applicable all applicable safety related criteria.

i safety related criteria.

i Not Required f

Redundancy Not Required Not Required Diversity Required. See Section C.3.3.4 of this guide.

from existing EDGs Required if connected to Class IE battery Ll;g ni ;;e Required if connected to Class IE buses. Seper- systems. Separation to be provided by two stion to be provided by two circuit breakers in from existing breakers in series (1 Class IE at the safety related series (1 Class IE at the Class IE bus Class IE bus and 1 non-Class IE).

l systems and 1 nan-Class IE).

Not Required Not Required I Seismic i' Qualifications ,..

4 Required, if nomal cooling is lost, for station Required, if nomal coolingt is lost, for Environmental blackout event only and not for accident condi- station blackout event only and not for Consideration accident conditions. Procedures should be tions. Procedures should be in place to effect in place to effect the actions necessary to the actions necessary to maintain acceptable maintain acceptable environmental conditions environmental cr*ditions for the required ec;uip- for the required equipuent. See Section l

' ment. See Secties C.3.2.4 of this Guide. C.3.2.4 or this Guide.

36

l e

l i

appendixs(contd1 .

Guidance Regarding System and Station Equipment Specifications (Cont'd) l Alternate Battery System (s)

Systems: Alternate AC Source (s)

Guidance:

Requ* red to meet 10CFR50,150.63 Capacity Required as specified in 10CFR50, 150.63 a M Section C 3.3.1 of this Guide.

and Section C.3.3.4 of this Guide.

Required as indicated in Section Quality Required as indicated in Section C.3.5 C.3.5 of this Guide.

Assurance of this Guide.

Requirement to be applied consistent with Technical Requirement to be applied consistent with the Interim Comunission Policy Statement Specification the Interim Commission Policy Statement on Technical Specifications (Federal for Maintenance, on Technical Specifications (Federal Register Notice dated ).

LCO, etc. Register Notice dated ).

Required to meet system functional Instrumentation Required to meet system functional requirements requirements and monitoring Not Required Stngle ratlure Ret aegufred Design should, to the extent pratticable, Common Cause Design should, to the extent practicable. minimize CCF between safety related and Failure (CCF)  ?

minimize CCF between safety related and non-safety related systbes .

"non-safety related systeers 4

37

Appendin_5IContdl Guidance Regarding System and Station Equipment specifications (Cont'd)

Water Water source

- Inttrument Air Delivery System Systuus: (Compstrssed Air System)

(existing condensate (Alternate to auxiliary Guidance-storage tant or alternatel feedwater system, E Tt',

system or condenser isolation makeup) i

\ Not Required but the Not Re wired but the Safety Related Ilot Required but the imp?cmentation must be implementation must be implementation must be such that the existing IEEE-279 such that the existing such that the existing Class IE system continues Class IE systems continue Class IE systems continue to meet all applicable to swet all applicabic to meet all applicable safety related criteria.

i safety related criteria. safety related criteria.

Not Required Not Required Redundancy Not Required Not Required Not Required Diverstty Not Required Ensure that the existing Ensure that the existing Independence Ensure that the existing safety functions are not l safety functions are not safety functions are not i From Safety compromised, including the compromised including the Related Systeers compromised incinding the capability to isolate j

capability to isolate capability to isolate components, sub-systems, or components, sub-systems, or cosponents, sub-systems, or piping, if required.

piping, if required. piping, if required.

l Not Reqlitred

' ' Not Required Not Required Seismic Qualifications 38 ,

i Appendix 8(Contdl

• i Guidance Regarding System and Station Equipment Specifications (Cont'd) a Water l Inttrument Air Delivery System Systems: ifater sourte (Comp M ssed Air System)_

[existino condensate (Alternate to auxilia feedwater system, RET

! storage tank or alternate)

Guidance: system or isolation condenser makeup)

Required for station blackout Required for station blackout i

Required for station blackout event only and not for DBA event only and not for DBA Environmental event only and not for DBA conditions. Refer to Section Considerations conditions. Refer to Section conditions. Refer to Section C.3.2.4 of this Guide. Pro-l C.3.2.4 of this Guide. pro- C.3.2.4 of this Guide. Pro- cedures should be in place to cedures should be in place to effect the actions necessary cedures should be in place to effect the actions necessary l effect the actions necessary to maintain acceptable environ-l to maintain acceptable environ- to maintain acceptable environ- mental conditions for the re-mental conditions for the re- quired equipment.

mental conditions for the re- quired equipment.

quired equipment.

Sufficient compressed The capacity to provide Capability to provide air to components,as sufficient cooling water Capacity l sufficient amount of wter necessary, to ensure flow to ensure that

! for core cooling in the event the core is cooled in 1

of a Fletion Blackout for that the core is cooled the event of a Station and appropriate containment the specified duration to Integrity is maintained for Blackout for the i meet 10 CFR Part 50,$50.63 specified duration to meet l and this regulatory guide. the specified duration of Station Blackout to meet 10 CFR Part 50 and $50.63.

10 CFR Part 50, 550.63 S*

i and this regulatory guide. .-

l  ?

Required as indicated Requir'ed as indicated 1

' Quality Required as indicated in Section C.3.5 in Section C.3.5

Assurance in Section C.3.5 of this Guide. of this Guide.

' of this Guide.

1 I .

1 39 k

l l

1__ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. _ . _ _ _ _ _ _ _ _ _ _ _ _. __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

l l

l .

I

\

I Appendix 5(Contdl Guidance Regarding System and Station Equipment Specifications (Cont'd) i Water Water source Inurument Air Delivery System l Systems: (Compikssed Air System)

[ existing condensate (Alternate to auxiliary Guidance:

storage tank or alternate) feedwater system, RCIC system or isolation condenser makeup)

Requirement to be applied Requirement to be applied Technical Requirement to be applied consistent with the Interim consistent with the Interim consistent with the Interim Cosmission Policy Statement j Specifications Commission Policy Statement Commission Policy Statement I

for maintenance. on Technical Specifications on Technical spectrications surveillance, LC0 on Technical Specifications (Federal Register F-tice _).

i (Federal Register Notice _). (Federal Register Notice _).

i etc.

i Required to meet Required to meet Instrumentation Required to meet system functional j

system functional system functional and Monitoring requirements. requirements.

I requirements.

Not Required Not Required Single Failure Not Required i

Design should, to the extent Design should, to the extent Caumen Cause Design should, to the extent practicable, minimize CCF practicable, minimize CCF practic 61e. minimize CCF between safety related and l

Failure (CCF) between safety related and between safety related and j non-safety related systems. non-safety relsted systems.

non-safety related system 2.

8 .

40 1

1 l

l

Appendix 8(Contdl -

1 Guidance Regarding System and Station Equipment Specifications (Cont'd)

.. Instrumentation, contro1_

RCS Makeup System Isolatten condenser Room Indications For Verif-System: ~(BWRs w?thout RCIC]

l (pWRs & BWRs without RCIC) ication of RCS Natural Circulation (PWRs & BWRs_

Guidance: without RCICJ 4

I Not Required but the Not Required but the Not Required but the implementation must be Safety Related tuplementation must be such that the existing IEEE-279 1mplementation avst be such that the existing such that the existing Class IE systems continue Class IE systems continue to meet all applicable

' Class IE systems continue to -eet all applicable to meet s11 applicable safety related criteria. safety related criteria.

safety related criteria.

l Not Required

! Not Required Redundancy Not Required

! Not Required Not Required Diversity Not Required

1. Safety-grade isolation A asifunction of this Independence

1. Safety grade isolation instrumentation and devices required between devices between this monitoring system From Safety this RCS makeup system system and existing Related Systems safety-related systems. should not affect the and existing safety- design safety function related askeup water systens. of any safety rdlated

2. A salfunction of this instrumentation and

? 2. A malfunction of this non- non-safety related sys- monitoring , systems 8

safety grade makeup system powered by onsite or tem should not affect the 3

should not affect the design safety function of offsite ac power l design safety function of any safety-related systems. buses.

j i

any safety-related systems.

Not Required i

Not Required Not Required Seismic Qua11fications 41 t

i . ,

i .

Appendix 8(Contdl '

Guidance Regarding System and Station Equipment Specifications (Cont'd)_

! Instrumentation, Control RCS Makeup System Isolation Condenser Room Indications For Verif-System: (BWRs #sthout RCICJ Ication of RC5 Natural

! (MNts 5 BWRs without RCIC).

Circulation (PWRs & BWRs_

Guidance: without RCIC)

Required for Station Blackout Required for Station Blackout

\ neguired for Station Blackout event only end no; ror onA

.v.nt only and not for onA Eny t resumental conditions it normal cooling event only and not for dea conditions if nonnel cooling Considerations conditions if normal cooling is lost. Refer to Sectfon 1 is lost. Refer to Section C.3.2.4 of this Guide. Pro-is lost. Refer to Section C.3.2.4 of thfs Guide. Pro- cedures should be in place to C.3.2.4 of this Guide. Pre- cedures should be in place to cedures should be in place to effect the actions necessary effect the actions necessary effect the actions necessary to maintain acceptable environ-to maintain acceptable environ- to acintain acceptable environ- mental conditions for the re-mental conditions for the re- mental conditions for the re- quired equipment.

quired equipment.

quired equipent.

l Provide sufficient capacity Provide sufficient instru-Sufficient RCS makeup . mentation, control room in-Capacity for decay heat removal. Dur- dications for parameters re-required such that core ing the specified duration temperatures are maintained qui n d for verification o' l at acceptably low values con- of station blackout the iso- RCS natural circulation (

lation condenser-pool side i sidering a loss of RCP water requires water makeup sys-ing the specified duration inven wry through a Postu- tem powered by sources in- of Station Blackout.

lated RCP seal failure during i g n i.;t from onsite and the specified duration of offsite ac buses.

i station blackout with a sini- ~

mum assumed itCP seal Isakage ,

' of 20 gym per RCP.

Required as indicated in Required as indicated in Required as indicated in Quality Section C.3.5 of this Section C.3.5 of this Assurance Section C.3.5 of this Guide.

Gu1de.

Guide.

j 42

! i

2

~

Appendix B (Contd) l Guidance Negarding System and Station Equipment Specifications (Cont'd)

RCS Makeup System Isolagon Condenser Instrumentation. Control System:

(BWRs Without RCIC)

Room Indications For Verif-(F1Nts & BWRs without RCIC) ication of RC5 Matural

l Guidance: Circulation ( PWRs & BWRs I

without RCIC t

! Requirement to be applied Requirement to be applied Requirement to be applied I Tecinnical consistent with the Interim consistent with the Interim Specifications for consistent with the Interim Commission Policy Statement Commission Policy Statement unintenance, Commission Policy Statement on Technical Specifications on Technical Specifications on Technical Specifications surveillance LCO, (Federal Register Notice (Federal Register Notice etc. (Federal Register Notice dated ).

dated _ ). dated ).

l RegAfred to meet Required to meet Instrumentation system functional and Monitoring system functional requirements. requirements.

Not Required Not Required Sir.gle Failure Not Required j

Design should, to the Design should, to the Camon Cause Design should, to the extent practicable, extent practicable, extent practicable, minimize CCF between safety Failure (CCF) minimize CCF between safety minimize CCF bekeen safety related and non-safety related and non-safety related and non-safety related systewfi.

related systems. related systems.

y s

4 l

43

. . SEP 3 0 B87 i

1 MEMORANDUM FOR: Themis P. Speis, Deputy Director  !

for Geraric and Regulatory Issues Of fice of Nuclear Regulatory Research )

FROM: A. W. Ser(iz, Senior Task Manager Reactor and Plant Safety Issues Branch Division of Reactor and Plant Systems, RES 1

SUBJECT:

SUM 4ARY 0~ MEETING WITH NUCLEAR UTILITY GROUP ON STATIO% BLACKOUT (NUGSBO) ON USl A-44)

Heeting Date: September 24, 1987 a

Location: U.S. NRC 7920 Norfolk Avenue

. Bethesda, Maryland Purpose of Meeting: The purpose of this meeting was to continue staff discussions related to NUMARC-8700 for determining technical adequacy for referencing this report in RG I

1.155, "Station Blackout" Attendees: See attached attendees list

References:

(1) NUMARC-8700, Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors," Revision 0.0, September 21, 1987.

(2) Working Draf t RG 1.155, "Station Blackout" dated 9-23-87.

These meetings were directed at reviewing NUMARC-8700 and providing NUGSB0 with the staff's views regarding technical adequacy and acceptability of this report for referencing in RG 1.155.

cc: See Naxt Page s

lT lC EE. C 2 ?? A)0{'

, W//f

SEP 3 01987 T. Speis Progress is continuing, NUMARC-8700 is neari.; completion. Revisions necessary to ensure that NRC staff comments t-: needs are beln) incorporated.

Outstanding items are related to concerns ra sed by NRR/SPLB and HUGSBO's desire to add, or modify footnotes in Tables 3, 5 and 7 of the proposed RG 1.155. P. Baranowsky will need to be involve-: in the resolution of the proposed modification of these RG tables. I addition tech spec requirements (or related considerations) have not been fu'ly resolved at this time.

A follow-up meeting, is scheduled for Octobe 7,1987 (to conclude review of NUPARC-8700).

A. W. Serviz, Senior Task Manager

.- Reactor a d Plant Safety Issues Branch Division f Reactor and Plant Systems, RES

Enclosures:

1) Draf t Regulatory Guide 1.155

2) WJMARC-8700, Rev. 0.0 cc: w/o Enclosures A. Thadani P. Baranowsky A. Rubin M. Childers, NU/NUGSB0 M. McGarry, BCP&R/NUGSB0 w/ Enclosures POR OFC :DR?S:RPSIB :D :RPSIB :DRPS: SB :0RP :0R )  :  :

NAME' $ ASerkiz:jf $P ian $KK'tel $ .i liebs $ BSl ron $ $

DATE :09/1 V87 :09///87 :09/M /87 :09/ W 87 :09/9/87  :  :

OFFICIAL RECORD COPY l

i

ATTENDEES September 24, 1987 NUGSB0/NRC Staff Meeting NAME AFFILIATION 3 HONE Al Serkiz NRC/RES/RPSIB 3C. -492-7487 John W. Craig NRC/NRR/PSB 3 C'.- 4 92- 7595 J. H. Raval NRC/NRR/PSB 3C'.- 4 92- 9423 Faust Rosa, ,

NRC/NRR/SELB 30'.-492-9466 a, J. E. Knight NRC/NRR/ DEST /SELB 30;-492-7456 Paul Gill NRC/NRR/ DEST /SELB 30'.-492-9474 Harold Walker NRC/NRR/ DEST /SPLB 30;-492-9420 Stephen Maloney DEV0NRUE/NUGSB0 617-426-4550 Mike McGarry BCPR/NUGSB0 202-857-9833 Mike Childers NU/NUGSB0 203-665-3472 Charles S. Ondosh DEV0NRUE/NUGSB0 617-426-4550 Stephen D. Floyd CP&L/NUGSB0 919-836-6901 George Lapinsky NRC/DLPQ/LHFB 301-492-4886

_..__.._4_ _ _ .. . . _ _ . _ _ . _ . _ _ . . . . . . _ _ _ . . . - . . . _ _ . . . . . . _ _ _ _ _ _ . _

t D1572:Btff!'ON w/o Enclosures

-Reeting Attendees {

., . RES Cire ,.

' AES C ron DCS N -007 ORP5 C/F  !

< .9 RPSIB.R/F

Il 85teron i j'~ j WMinners.

KKr.iel .t ji4 - PNcaian

]j ASerki2 I$

l 4 ,

. h y ..

e

,i I i ,

i

)

2  !

i .

i  :

l l t

i l  ?

i 3

4 8

9 [

2

• g J

In

! n 3

1 h  !

l  :

l

[

i I i  ;

f I

L i

I E

4 W#

t I

' s

~ ~ ~

3,4g yj WOQX10(.e

.-$ ENCLOSURE 1 }f W  ;

1 i REGULATOPY GUIDE 1166 ST ATION BL ACK0UT_ .

(TASK SI 501-4) ..

A. lWTFTCTION Criterio 17, "Electric Power Systees," of Appeadix A, "General Design Criteria for nuclear Power Plants," to 10 CFR Part 50, "Domestic Licensing of Production and Utilization Facilities,' includes a requirement that an onsite

- electric powe system and an offsite electric power system.be provided to per-mit functioning of structures, systems, and components important to safety.

f The Commission has amended its regulations in 10 CFR Part 50. Paragraph l (a), "RequiremTe ts,' cf 450.63, ' Loss of All Alternating Current Power,"

requires that each light-water-cooled nuclear power plant be able to withstand and recover from a station blackout (i.e., loss of the offsite electric power )

system concurrent with reactor trip and unavailability of the onsite amergency ac electric power systee) of a specified duration. Section 150.63 requires that, for the station blackout duration, the plant be capable of maintaining core cool-ing and apprcpriate containment integrity. It also identifies the factors that must be considered in specifying the station blackout duration.

Criterion 18, "Inspection and Testing of Electric Power Systees," of Appendix A to 10 CFR Part 50 includes a requirement for appropriate periodic testing and inspection of electric power systems important to safety.

This guide describes a method acceptable to the NRC staff for complying with the Commission regulation that requires nuclear power plants to be capable of coping with a station blackout for a specified duration. This guide applies to all light-water-cooled nuclear power plants. ..

2 I

? O!!!^0l y q3y N/n

' Any inferr.atier. collectior activities related to tMs regulatorf g.ide are contained as reo ireinents i'. the revisien of 10 CFR Fart 50 that : :. ides the regulatory basis for this 9 ide. The information ccilection ret.' vents of the revised Part, 50 were ap;- ved by the Office of N .agerent aTc Lcget approval nuinber 315C-0011. This clearance applies to ar.f informattor ,

collection activities related t: this guide. ~

S. DISCUSSION The tere ' station blackout' refers to the complete loss of altemating current electric power to the essential and nonessential switchgear kses in a nuclear power plant. Station blackout therefore involves the loss of off-site power concurrent with tuttine trip and failure of the.onsite emergency ,

ac power system, kt not the 1:ss of available ac power te buses fed by station batteries through inverters or the loss of power from ' alternate ac sources."

Secease many station blackogend alternate ac source are defined in 150.2.

safety systees required for reactor core decay heat removal and containment heat recoval are dependent on ac power, the consequences of station blackout In the event of a station blackout, the capability to cool could be severe.

the reactor core would be dependent on the availability of systems that do not require ac power frts the essential and nonessential switchgear buses and on the ability to restore ac power ir a timely manner.

The concern about statio blackout arose because of the accumulated experience regarding the reliability of ac power supp1fes. Nny operating plants have experienced a total loss of offsite electric power, and acee occurrences are expected in the future. In almost every one of these loss-of-offsite power events, the ensite emergency ac power supplies have been available issediately to supply the power needed by vital safety ewipment.

However, in some testances, one of the redundant emergency ac power supplies 2

~

' has' beer unavailable. In a few cases there has been a complete loss of i:

power, b4 during these events, ac power was restered in a short time wi'.* Nt any sericus consequences. In addition, there rase been numerous instances when emergency diesel generators have failed t: start and run in tvsponst to tests comk.icted at operating plants. .

The results of the Reactor Safety Study (lef. 1) showed that, for o e of the two plants evaluated, a station blackout ever.t could be an important centrib-utor to tre total risk from nuclear power plart accidents. Although th's total risk was found to be small, the relative importance of station blackout events was established. This finding and the accumulated diesel generator fai'.rt experience increased the concern about statier, blackout.

In a Ccanission proceeding addressing station blackout, it was detemined that the issue should be analyzed to identify preventive or mitigative seasures that can or should be taken. (See Florida Power & Light Company (St Lucie Nuclear Power Plant, Unit No. 2) ALAB-603,12 WRC 30 (1980); modified CL1-81-12, u wac sas (19fD.)

The issue of station blackout involves tie likelihood and duration of the loss of offsite power, the redundancy and reliaoility of onsite emergen:y ac power systems, and the potential for severe accident sequences after a loss of all ac power. References 2 through 6 provide detailed analyses of these topics.

Based en risk studies perforined to date, the results indicate that estimated core melt frequencies from station blackout vary considerably for diffe ert plants ar>d could be a significant risk contrtWtor for some plants. InoNer to %ce this risk, action should be taken to resolve the safety conce r, stemning from station blackout. The issue is of concern for both PWRs and SWRs.

3

(l'; w intaining

' 'This guite prir.arily addresses the following tWe areas:

l highly relist'e ac electri: power systems, (2) deve' ;ing procedres and training l to restore o"site end onsite emergency ac power sh:.1d either one or both becore unavai are, and (E ensuring that plants co' cope with a Hation black-l out for some period of time based on the probability of occurrence of a station bli,ckout at a site as well as the capability for restering ac power in 'a timely - j f ashion for that site.

One f acur that affe:ts ac power systee relist".ity is the v>.1nerability to costnen ca6se failures associated with design, operational, and environmental l

factors. Existing standaNs and regulatory guides include specific design '

criteria and guidance on the independence of preferred (offsite) power circuits (see General Design Criterion 17. "Electric Power Systems,' and Section 5.1.3 f

)

- of Reference 7) and the independence of and limiting interactions between '

l diesel penerater units at a nuclear station (see General Design Criterion 17, l

Regulatory Estde 1.6, "Independence Between Redundant Standby (Onsite) Power l Sources and netween Their Distribution Systems," Regulatory Guide 1.75, In developing

• Physical IMndence of Electric Systems.* and Reference 8).

l the recossnetdations in this guide, the staff has assmed that, by adhering to such standarts, licensees have minimized, to the extent practical, single-point vulnerabilities in desige and operation that could result in a loss of all off- l site power cf all onsite energency ac power, l Onsite emergency at power system unavailability can be af fected by outages resulting f rom testing sad maintenance. Typically, this unavailability is about l

0.007 (Refe ence 4) which is small compared to the maximum emergency diesel generator rtliabtitty specified in Section C.1.1 cf this Regulatory Guide l

• I l

l 4

However, in some cases outages

, (i.e,. , 0.95 or 0.975 reliabi1Wy per demand).

out te raintenance can be a sigrificant contributor to emergency diesel generator unavailability. This contribution can be kept low by hav'as high quality test and maintenance procedures and by scheduling regular gesel generator maintenance at times when the reactor is shut down. Also, limiting conditions for operation in the technical specifications are designed to limit the diesel generator unavailability when the plant is operating. As long as the unavailability due to test and maintenance is not excessive, the maximum eee ge :y diesel generator failure rates for each diesel generator specified in Sectier C.1.1 would result ir, acceptable overall reliability for the emergency ac power systee.

Based on 550.63, all licensees and applicants are required to assess the capability of their plants te maintain adequate core cooling and ap3ropriate contairunent integrity during a station blackout and to have procedcts to cope with such an event. This guide presents a method acceptable to the kE staff for deterinining the specified duration for which a plant should be able to with.

. stand a station 41ackout in accordance with these requirements. The application of this method results in selecting a minimum acceptable station blackout duratien capability fror 2 to 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> depending on a comparison of the plart's char-acteristics with those factors that have been identified as significantly affecting the risk from station blackout. These factors include redundancy of the onsite emergency ac power system (i.e., the number of diesel generators available for decay heat reecval minus the nurber needed for decay kat recoval), the reliability of onsite emergency ac pom t,urces (e.g., diesel generators), the frequency of loss of offsite power, and the proba 1e time to restort offsite power.

5

, , Licensees ray p'opese durations different frorn those specified in this guide. The basis fe' alternative durations ww1c be prediated on plant specific factces relating tc tre reliability of ac power systems su: as those discussed ir. Re'erence 2.

Concurrent witt the develo$ ment of this regulatory gu'$e, and 1n consulta- ,

tion with the staff, the Nuclear Management and Resource Council (N! MARC) de-veloped guidelines ud procedures for assessing station blackout coping capabil-ity and duration fo' 1);ht water reactors. De s ta f f has e. iewed these guide-lines ar.d analysis sethods which are reported in NLHARC-87*.C Rey, _, ,

1957 an: concludes that this report provides guidance for confonnance to 50.63 that is in large part identical to the guidance provided is this regulatory guider.

Table .) _ of this regulatory guide provides a section by section comparison

. between RG 1.155 and ILPARC - 8700. The use of NUMARC - 8700 is further dis- ,

cussed ir. the follwing Section C. Regulatory Position.

C. REGULATORY POSITION

'o*

This regulatory pide describes a means acceptable to the staff for meeting the regirements of 50.63. NtMARC - 8700 also provides guidance acceptable to the staf f for setting these requiresents, with the exceptians noted in Table

,I ,,

For these identified exceptions, the guidance in tais regulatory guide should be used.

1. ONSITE DEREDCY AC POWER SOURCES (EDG) 1.1 ED6 Target neliability Levels The minimum IM reliability should be targeted at 0.95 per demand for each EDG for plants in Isergency AC (EAC) Groups A B.C and at C.975 per deeand for each EDG for plants in EAC Group D (see Table 1). These reliability levels will i be considered einism target re11 abilities and each plant should have an EDG re-liability program cautaining the principal elements, or twivalent, as defined in Section 1.2. Plasts iMch select a target EDG reliability of 0.975 mill utilize the higher level a the target in their EDG reliability programs.

6 I

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

. , The EDG reliability for detenniring SB0 coping duration 0C1 be deterr e:

as fellows:

(1) Calculate the ecst recent EDG reliability for ea:h M based on the last 20, 50 anc 100 demands using definittoms and mettee- ,

ology in section 2 of itSAC-108 The Reliability of Emergency

-- sengators at US Nuclear Power Plants (September 1985for equivalt nt.*

(2) Calculate the nuclear unit ' average" EDG reliat lity for the last 20, 50 and 100 derancs by averaging the res A ts from ste:

(1)above.

(3) Compare the calculated ' average" nuclear unit DG reliabilitj ,

fron step 2 above against the following criteria:

Last 20 derands 0.90 reliability

1. Last 50 demands 0.94 reliability Last 100 demands 0.95 reliability (4) If the EA* group is A,8,C E0 0 any of the three evaluation

- criteria in step 3 are met, then the nuclear writ may select an EDG reliability taget of either 0.95 or 0.975 for deter-mining the applicable coping duration froe Tab'e 1. If the EAC grou; is D, and any of the three evaluatier criteria in step 3 are met, then the allowed EDG reliability target is 0.975.

(5) If, for EAC groups A,8 and C NONE of the selection criteria ir Step 3 are met, then an EDG reliability level of 0.95 must k utt11:ed for 6termining the applicable coping duration fror

• This EDG reliability is not suitable for PRA(s) for design basis accidents because of the differtog EDG start reliability requirement that would be applicable for och N(s).

]

l 7

1sti e 1. If the "averagec' nuclear unit EDG reliability is aise less than 0.90 based on tre last 20 der.e .ds then acceptability c' a coping duration basec cr using an E*,5 reliability of 0.95 fece- Table 1 must be furtr4r justified.

If the EAC group is D and noce of the three evaluation,, criteria

- te step 3 are met, the resulting required coping duration (See Tatie 1) resulting from step 3 will be ir. creased to the next tig*est coping level (i.e. 4-hours bec:me 6-hours, 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> be::res 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />).

12 Reliattlity Program

~

The relistle operation of on-site emergency AC power sources should be ..-

em. ed by a reliability program designed to maintain and monitor the reliability lece' of each power source over time for assurance that the selected reliability An EDG reliability prograr would typically be comprised levels are beigachieved. * -

as the following elements or activities (or equivalant):

(1) Establistunent of individual EDG reliability target levels con-sistent with the plant category and coping duration selected from Table 1.

(2) Surveillance testing and reliability acnitoring programs designed te track EDG perfomance and also support maintenance activities.

I (3) A maintenance program which ensures that the target EDG reliabil-ity is being achieved and which also provides a capability for f ailure analysis and root cause investigations.

4 (4) An information and data collection systta capability which services the elements of the reliability program and which somiters achieved EDG reliability levels against target values.

8

' (5) Ideratfied responsibilities for the major program eleme :s and a sanagement crersight program for reviewing reliat *.ity leve's being achieved and assuring that the program is '

functioning properly.

Procedures for Restoring Emergency AC Power 1.3 -

huidelines and procedures for actions to restore emergency a: power when the energency se power syste- is unavailable should be integratec of th plant-specific teche.ical guidelines and emergency operating procedures developed using the emergency operating procedure upgrade program established ir response to Supplenent 1, "Requirements for Emergency Response Capability" (Gereric letter No. 82-33).I to MtHG-0737 "Clarification of TMI Action Plan Requirements."

2. OFFSITE K4TR Procedures should include the actions necessary to restore effsite

1. e when offsite power is unavailable. As a power and use nearty power sourcas minimum, the following potential causes for loss of offsite power sho;1d be considered:

• Grid undervoltage and collapse.

• Weathe-induced power loss. l

• Preferred power distribution system faults 8 that could result in the f loss of ncruel power te essential switchgear buses.

i I modifications er additions to generic technical guidelines that are necessary I to deal with a station blackout for the specific plant design should be identified as deviations is the plant-specific technical guidelines as required by Supplement I to NUREG-0737 and outlined in NUREG 0899. "Guidelines for the Preparation of Emergency 5 rating Procedures."

8 This includes such items as nearby or onsite gas turbine generators. portable generators lt dre generators, and black-start fossil power plants.

s Includes such failurts as the distribution system hardare, switching and maintenance errors and lightning-induced faults. ,

i

. _ _ _ _ , . _ _ _ _ - . . - _ _ - _, . , , . _ ~ . _ . . , _ _ _ - . _ _ . - .---,m___. _ _ - , . . . . , . _ _ _ _ , _ _ . . - - _ _ . , , . . . , _ - _ , _ _ _ _ _ _ _ _ _ _ , _ . . - _ - - - . . , - . - - - , . _ ,

. .. A!'LITY TO C0Pt WITH A STA 10N BLACKOUT de ability to cope with a station blackout for a certain time p c. ides i

accitional defense in-depth should bcth offsite and onsite energenty ac pove-systec.s f a') concurrently. Section C.3.1 provides a method to detersine a' ,

j acceptable minimum tire that a plant should be able to cope with a statfor ~

tlackout based on the probability of a station blackout at the site as wel' as  !

the capabi.iity for restoring ac power for that site. Each nuclear power p* ant r.as the ca;4tility to remove decay heat without a: power for a litrited pe ec I cf tire.

Section C.3,2 provides guidance for determining the length of tine that a pla t is actually able to cope with a station blackout. If the pla t s '

actual station blackout capability is significantly less than the acceptat'e l

sinisun duration, modifications may be necessary to extend the plant's abi*ity to cope w th a station blackout. Should plant modifications be necessary.

i ,

Section C.3.3 provides guidance on making such modifications. Whether or act modifications are necessary, procedures and training for station blackout events should, #be provided according to the guidance in Section C.3.4 Minimum Acceptable Station Blackout Duration Capability 3.1 Each nuclear power plant should be able to withstand and recover frw. a station blackout lasting a specified minimum duration. The specified duratior. of station blackout should be based on the following factors:

a. The redundancy of the onsite emergency ac power system (i.e., tae rnsber of power sources available minus the nur.ber needed for decay heat renoval),

b. The reliability of each of the onsite emergency ac power sources (e.g., diesel generator),

b P

10

'c.

The es;4cted freq6ency of loss of offsite power, and

d. The probable time needed to restore offsite power.

A method for detersining an acceptable minisum station b ackout duration capatility as a function of the above site- and plant-related char-i acteristics is given in Table 1. Tables 2 through 7 provide the nece;ssary

• detailed descriptions and definitions of the various factors used in Table 1.

Table 2 identifies different levels of redundancy of the onsite ener9ency ac j power system 6see to define the einergency ac power configuration g ovps in Table 1. Tabie 3 provides definitions of the three offsite power design char-acteristic groups used in Table 1. The groups are defined accordlig to various combinations of the following factors: (1) independence of offsite power (1).

(2) severe weather (SW) (3) severe weather recovery ($WR) and (4) extremely '-

severe weathe' (E5W). The definitions of the factors 1. Se, SWR, and ESW are provided in Table 4 through 7. respectively. Af ter identifying tie appropriate groups from Tables 2 and 3 and the reliability level of the onsita emergency ac power sourt&b,(determined in accordance with Section C.I.1 of this regula-tory guide). Table 1 can be used to detersine the acceptable minimum station blackout duration capability for each plant.

3.2 Evaluation of Plant-Specific Station Blackout Capability Each nuclear power plant should be evaluated to determine its capability te withstand and recover from a station blackout of the acceptable duration determined for that plant in Section C.3.1. The following considera-tions should be included when determining the plant's capability to cope with a station blackout:

3.2.1. The evaluation should be performed assuming that the plant is operating at full power immediately before the postulated station blackout.

11

The capability of all systees and cos;cnents necessary to pm.'ce core 3.2.2.

coclir; and decay heat removal ':* lowing a station blackout should be :eterrined, i

incht'n; station battery capac'tf, condensate storage tank capaci,ty, :or:ressed air capcity, and instrumentativ and control requirements. .

The ability to minta'n adequate reactor coolant system iny.entcry to

. 3.2.3.

ensure that the core is cooled shculd be evaluated taking into conside-ation l shrieka;e, leakage frce pur.p seals, and inverte*y loss from letdown o' cther norwily open lines deperdent at ac power for isolation.

The design adequacy asd capability of equipment needed to ctoe with 3.2.4 station blackout should be addrtssert and evaluated as appropriate for the environ-l l

mental conditions associated with a station blackout for the required Aration -

and recovery period. This shodd include, consideration as appropris.e of the following:

1 1

1. potegJai failures of equipment necessary to cope with station blackout l

2. potential envirormental effects on the operability and reliability of equipment necessary to cope with station blackout

3. petential effects of other hazards, such as weather, on station black-out response equipmett (e.g., auxiliary equipment to operate on site buses or to recover EDEs and other equipment as needed).

4. pote.ntial habitability concerns for those areas which woult require operator access durteg the station blackout and recovery period.

Evaluations that have already been perfortned rmed not be dio11cated.

For example, if safety related equipment required during a total loss of ac power has been qualified to operate under environmental conditions exceedtag those ex-pected under a staties.blackott (e.g., loss of heating, ventilation and air conditioning) addittomal aulyses need not be performed. Equipment "will be con-sidered qualified for station blackout temperature envirorsnents if si assessment has been performed that provices reasonable assurance that the requ' e4 equiprent will remain operable.

12

' should be given to usin; available ne -safety-related 3,j.5. Censideratiot l k eq,ipment, as wc11 as sa'ety related equipment, te cope of Sections C.3.3,.3 and Cwith 3.3.4 a station b ac ou prowided such equipmer'. netts the recceendatio".5 Onsite or nearby alternate ac (AAC. power sources of this regulatory guice.

that are independent a4 diverse from the nortc1 Class 1E eme gency ac power sources (e.g., gas tur*.ine, separate diesel engine, steare supslies) w.111 constitute an acceptat'e station blackout coping capability nvided an analysi is performed that deocastrates the plant has this capability free the onset o the AAC power source (s) is started anc lined up to operate station blackout unti all equi;sent necessary to cope with station blackout for the required plant duration.

In general, equipment required to cope with a station blackout during For equipment not located on the first 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> shald be available on site.

site, consideration skuld be given to its availability and accessibility w the time required. includiaf consideration of weather conditions likely to prevail during a loss Akoffsita pwer.

If the AAC source (s) meets the above requirements and can be decon-strated by test to be available within 10 minutes of the onset of station blac then no coping analysis is required.

Considerati:e should be given to timly operator a:tions inside or 3.2.6.

outside the control room that would increase the length of tire that the plant cr.n cope with a station blackout provided it can be demonstrated that these For example, if station battery actions car, be carried est in a timely fashion.

capacity is a limitial f actor in coping with a station blackout, shedding non-essential loads on the batteries could extend the time until the battery is If load shedding or other operator actions are censidered, correspond-depleted.

ing procedures shovid be incorporated into the plant-specific technical gu lines and energesc7 8Persting procedures.

The ability ts maintain 'Appropriata Contairunent Integrity" should be 3.2.7

' Appropriate Contaireent Integrity" for station blackout'is defined addressed.

such that adequate caetaissent integrity is euured by providing AC independ 13

u:tbility for indication c' valve positice arid AC independent ca- a tility of c :5.are for containment isclation valves identified in technical 5;e:ificatiers v~t:5 may be in the open ocsition et the oeset of a station blacko 1. The f o':: -

ing valves are excluded fri.e consideration:

(1) a,r,11y locked closed during operation ,,

(2) 3 fail closed on a loss of power (3) chet.a valves (4) valves in non-radioactive closed-loop systems not expected to te breached in a station blackout (this does not include lines which comuricate directly with containmentitmosphere)

(5) velves of less than 3' nominal diameter.

14

l,

' 3,3

• Modificet' ens to Cope with StJ2 ice l'.ackout l

If the plant's station blackout capabity, as dete vined according .o che guicance in Secti:e C.3.2 of this regulate f guide, is significant+y less than the sirimum acceptable plant-specific station blackout Aration as developed acccrding to Secticn C.3.1 of this regulatery guide (or as justifiad by' the licensee or ipplicant on some other basis ene accepted t f the staff)l'modifi-

-cations to the plant may be necessary to esteed the time the plant is able to cope with a stati:r. blackout. If mocificatic-s are needed, the following items should be censidered:

3.3.1. If, after considering load shedding to extend the time until battery depletion, battery capacity must be extended further to meet the station blackov:

duration recommen$4d in Section C.3.1 of this regulatory guide, it is considered acceptable either to add batteries or to add a charging system for the existing batteries that is independent of both the offsite and oesite emergency ac power systems such as a dedicated diesel generator.

' es5 3.3.2 If the capacity of the condensata storage tank is not sufficient to remove decay heat for the station blackout duration recommended in Section C.3.1.

of this regulatory guide, a system to resupply the tank from an alternative '

unter source is an acceptable means to increase its caMcity provided any power source necessary to provide additional water is indeper4ent of both the offsite and the onsite emergency ac power systems.

3.3.3 If a system is required for primary coolant charging and makeup, reactor coolant pag seal cooling or inje: tion, or decay heat removal specificaliy to meet the station blackout duration recommended in Section C.3.1 of this regulatory guide, the following criteria should be met:

a. The system should be capable of being actuated and controlled from the control room, or if other means of control are required, it should be desonstrated that these steps can be carried out in a timely ..

fashion; and 15 1

)

b. I' the syster mst operste within 10 r'n.*.es of a less s' all se power, it should be capable c' being actue e:

'ece the control room.

3.3.4 If an altemate ac (AAC) power source is selecte: specifically for satisfying the requirerents for station blackout, the design should eget the following criteria;

a. The AAC power source should not normal */ be directly connected to the preferred or onsite ener?ency ac pp.er 5ys tem.

b. There should be a minimum potential fo comon cause failure

~

vith the preferred or the onsite emergency ac power sources. .

k, single point vulnerability should esist whereby a weather  :

l related event or single active failure could disable any l

. portion of the onsite emergency ac power sources or the pre-ferred power sources, and simultaneous *y fail the MC power source (s). ,

1

c. The AAC power source should be availab'e in a timels manner after the onset of station blackout anf have provisions te be unus11y :onnected to one or all bcses as req. ired of the redundant safety buses. The time 'equired for asking this equipment available should not be acre than ore hour as demonstrated by test.

d. The AAC power source should have sufficient capacity for operation of the systems necessary for coping with station blackout for the time requiret to bring anc main-tain the plant in safe shutdown.

16

e. The AAC power systen stCd be inspe:ted, maintained and testM periodically to demons *. rate operabi'ity and reliability. T t.t reliability of the AAC pcwer systet should meet or exceed SE percent as deteririned in accordance with NSAC-108 methodolog (orequivalent). .

L.

Arr AAC power source (s) serving a multiple unit site where onsite ene -

9ency ac scurce(s) are not shared between units sh:vid have, as a minimum, tne capacity ar.d capability for coping wi;r. station b9acteut in any of the uniti.

At sites where onsite emergency sources are shared between units, tr.e AAC power source (s) should have the capacity and capability as required to assure that all units can be brought to and maintained in safe shutdown (hc:

shutdown or hot standby as appropriata).

Flants which have more thar. the requirec redundancy of emergency ac source (s) for gps of offsite power conditions, or a per nuclear unit basis, may use one of the existing emergency sources as an AAC power scurce provided it meets the above applicable requirmeets for an AA0 source.

3.3.5 If a system or component is added specifically to meet the reccawn-

! dationi, on station blackout duration in Section C.3.1 of this regulatory gtide, system walk downs and initial tests of new or moeified systems or critical l

- components should be performed to verify that the modifications were performed properly. Failures of added componests that may be vulnerable to internal or external hazards within the design basis (e.g. seismic events) should not result in secondary failures causing a loss of emergency ac power systems er a loss of other safety-related equipment.

3.3.6 A systee or component added specifically to meet the recossendations on station blackout tiration in Section C.3.1 of this regulatory guide shotid be inspected, maintaimd and tasted periodically to demonstrate equipment operability and reliability. -

17 l

1 I

3[ Frote:. es and Trair' ; to Cope with Statier l'a:kout Procedures' ar.: training sWid include all operat:r actions ne:essary to cope with a stat sr blackout f:r at least the duration determined acccrding to Section C.3.1 of this regulate y guide, and to restore nerv.a1 tong-terr. core cooling / decay bett re: novel once ac power is restored. ,,

3.5 Qualit., Assurance Ard Specification Guidance For Station Blacu.: Equipment i..4: Is Not Safety-Relate:

Apper. dices A and B provice the guidance for quality assurance (W activities and sxcifications respectively for non-safety related eo.ipenent for which credit is taken in the resciution of Station Bla:kout (Generic Issue A-44) . Appropriate activities shall be implemented free among those listed in ,

these appendices depending on st4ther the non-safety ecuipment is being added (new) or is existing. This OA guidance is applicable to non-:afety systems and equipment for, setting the req 6trements of 10 CFR 50.63. The guidance on QA and specification ffcorporates the lesser degree of stringency by eliminating requirements for involvement ef parties outside the normal line organization and requirements for a formalfred program and detailed recordkeeping for all quality practices as required for safety-related equipment. NRC inspections will focus on the implementativ. and effectiveness of the quality controls whose attributes are described in the appendices A and B.

Additionally, the equipeent installed ta meet the station blackout rule must be impleser.ted such that it does act degrade the existing safety related systems. This is to be accomplished by making the non-s,afety related equipment independent to the If the nor-safety sys-extent practicable fras existing safety related systems.

taas identified in appendix 5 are utilized for responding to a station blackout, the guidance provided in appeedix B is acceptsble to the staff for those systems.

4 Procedures shes1d be lategrated with plant-specific technical guidelines and energeon aperating procedures developed using the emergency operating procedure upgrade progres established in response to Supplement 1 of (UREG-0737. De task analysis portion of the emergency operating procedure i

,Jpgrade progres should include an analysis of instrumentation adequacy during a station blachaut.

18 l

- . . . _ _ ___ _ _ ~ - . - _ . _ _ -__ _ __ _ __ _ _ _ _ . _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ - -

D. IM LEMENTATION 1he purpose of this section is te provide inforretion to appl 1 cants and ,

licensees regarding the NRC staff's plans for using this regulatory guide.

Except in those cases in which the applicant or licensee proposes an accept-able alternative methods for complying with specified portions of the Comrission's regulations.- the method described in this guide will be used in the evaluation of submittals by applicants for construction permits and operating licenses and The by licensees who are required to cor;'y with 150.63, "Station Blackout."

rule requiret that the submittal be a FSAR amendment. It is expected that a licentee or an applicant will have available for review, as required, the ar.alyses and related inferration that supports the submittal.

I i

l l

19 l

. - . , . . _ - . . . - - - - , . . , , . _ . . _ _ _ _ . - , _ _ - - - - - ~ _ - , . - - , _ , . _ , - . _ ,y..- - . , - - , _

Table 1 A::e; table Station Blackout Duration Capadlity (hours)*

j D

Emergency AC Powe Configuration Group

- A B C D Unit "Avera;e" EDG Reliability Of f site Po.er Design C

Characte istic Group 0.975 0.95 0.975 C.95 0.975 0.95 0.975 2 2 4 4 4 4 4 P1 4 4 4 4 4 8 8 P2 4 8 4 8 8 16 8 P3 a Variations froe these times will be considered by the staff if justification, including a, cost benefit analysis, is provided by the licensee. The methodol-ogy and sensitivity studies presented in NUREG-1032 (Ref. 2) are acceptable for use in this justification.

bSee Table 2 to determine emergency ac power configaration group.

cSee Table 3 to determine groups P1, P2, and P3.

20

I Table 2 l -

Emergency AC Power Configuration Groups'

, ~

Number of LW, iower 5:veces l Emergency AC (EAC) NumbergfEACPower Required to vperate A*-Powgred l

Sources Powe- Configuration Decay Heat Re-eval Spie-s ,

Group 3 1 A 5 1 4

~

4 2 .

g 2 5

1 p 2 C 3 1 2 1 0 3 2 4 3 3

5 8 Special purpose dedicated diesel generators, such as those associated with high pressure core spray systees at some SWRs, are not counted in ne determination of EAC power c:nfiguration groups.

b 1f any of the EAC power. sources are shared among units at a multi-anf t site, this is the total r, umber of sharea and dedicated sources for those units at the site.

"This number is based on all the ac loads required to remove decay heat (including AC-powered decay heat removal systems) to achieve and maintain het shutdown all units at the site with offsite power unavailable.

• I d For EAC power sources act shared with other units.

'For EAC power sources shared with another unit at a multi-unit sitit.

I For shared EAC power sources in which each' diesel generator is cacable of pro-viding at power ta more thai one unit at a site concurrently, l

)

r

( 21

921-67 hr-r S Ayk.L T(WLL X CRCSS REFERENCE OF STATION BLACK 0J R.G. 1.155 TO NUMARC 8700 R.G. SECTION C NUMARC 8700 1.1 3.2.3, 3.2.4 1.2 Appendix D 1.3 4.2.1, 4.3.1 2 4.2.2, 4.3.2 3.1 3 3.2.1 2.2.1, 2.2.2 7.2.1, 7.2.2, 7.2.3,' 2.9

~

~ 3.2.2 3.2.3 2.5 3.2.4 2.7, 7.2.4, Appendix E g 3.2.5 # 3.3.3, 7.1.1, 7.1.2, Appendix) .

3.2.6 4.2.1, 4.3.1, 7.2.1, 7.2.2, 7.2.3 3.2.7 7.2.5 3.3.1 7.2.2 l 3.3.2 - - -

7.2.1 ~

1

- ~ ~ "

No reference 3.3.3  !

3.3.4 2.3.1, Appendix A, Appendix B 3.3.5 No reference '!

3.3.6 4.2.1(12), 4.3.1(12),3.3.3, 400. A and B l 3.4 4 3.5 No rsference ,

7P it/.e AA< A ,

1 l 1tr R r.kv% '

)7

// .

f Ow w

Table 3 Offsite Power Design Characteristic Groups Group Offsite Power Design Characteristics -  !

" ~

Sites that nave any combination of the following f actors:

8 b gyp e d 1 SW ESW fl 1o2 1 or 2 1 or 2 1 or 2 1 or 2 1 1 or 2 3 1o2 3 1 1 or 2 P2 All other sites not in P1 or P3.

Sites that expect to experience a total loss of offsite power caused by grid failures at a frequency equal to or greater than once in 20 site years, unless the site has j proced.ues to recover ac power from reliable alternative (nonemergency) ac power sources within approximately l one half hour following a grid failure.

0.I Sites that have any combination of the following factors:

P3 I SW SWR ESW Any I 5 2 Any ESW Any 1 1,2,3, or 4 1 or 2 5 Any I 5 1 Any ESW Any I 4 2 1,2,3 or 4 1 o- 2 3 2 4 3 3 2 3 or 4 a

See Tat'.e 4 for definitions of independence of offsite power groups (!).

b See Table 5 for definitions of severe weather groups (SW).

C See Table 6 for definitions of severe weather recovery groups (SWR).

d See Table 7 for definitions of extremely severe weather groups (ESW).

22

k

.efi.itie.s .e i c = e .f eefsite cover cre.s. i 1 -

1 j _ __

L_ ___

== % -y

( All ef fstte power seerces are cen cted to the plaat theev# '

A11 offette pomee sewetes are oa. n=lichfare.

a& tee.gence of offsite j ceanected t. the ,isat thee.sh er i e soon es two er more sultchyards er seperate l

a lateenlag transelssion Itaes, but at Att ef feste s.-er swertes = coaaected to the n, tent thee sh t e

teost eae of the oc so.rces to se moce s.stce. reeds, and the switchyards la Flgwre 2 mrepresent eintescat this sy c.aanted.

destga eiectreratty sade,eaeens of the (The 3eS- and t)4-tv switchyards sthers. (The ladepeadrat 69-hv Itae la flgure 3 is eepeesentatfee festere.)

l et this destga featwee.)

j

( d d E If the morest source of oc power If the seemet seerte of ac power Aftee less of the aeruel se peaer falls, there are me setenettc f faits, there la en setematic seerte there is one swtematte treasters sad one oc more meae 1 transfer to e preferred sourte of transfer. If this source falls, treasters to perferred ee alternate i

there may be eae er more maaeel siy power. If this preferred severe ef. site - r s n es. one

) b ile and eensel teensfee of ,s.or f.iis, u.ere is sa s.te- tra.sfers .f r so.n es t.

e,e= (se) meaesity a,eested eties.es f.c the ciass it b.se. peeferred or alternete offsete carcits to the Class It buses as den the noemet seerte of ec power matec transfer to aaether se=rce of poner seertes. (The saavat offsite power. (fbe transfer from shown la figure 3 are representatlee e_glis and when the backup se m es the 161-tv sete-treasterner to the transfer from the owte-transformer of this des 6en feature.)

97 offilte power fail 69-hv seeece in f lgere I to repre- to the 69-4, sorece en flgwre 3 O s sentattee of this destym festere.) espeesentottee of this destga feetwee estopt thea treasfer from the aute-transformer to the 69-av l

soorte would be manual. )

er If the normel soorte of oc power If the =orest soorte cf sc power j

! falls, there is one estomatic falls there is one avtomatic cransfer but no mecost treasters to transfer bwt ae maawat treastees preferred er alternate offstte to preferred or alternate offsete J

power sources.

power sowrces.

f, The Class It beses in a unit are All of the Class it beses la a unit ceanected to separate offstte power are connected to the tsame preferred

] power sowete af ter 184 setonatic l searces after the automat 6c t r ans f er gf power sources . (fhe treaster of po-er sowrces. (The 1

I transfer to the two 136-tv s ettch- , transfer of the Class it bwses from one preferred towrce te another yard sources la figure 2 ts repre- preferred source la figure 3 is

! sentative of this destga featwee.) reerescatattwe of this destga of I - the treasfer were avtomat6c tastead l of maawal.)

j ..

!I i 73 i

Table 5 De'initions of Severe Weather Groups (Si Estimated f requengy of loss of of f site sc<er d'ue SW Group severe weather, f (per site year) ,

1 . f < 0.003S .

2 0.003A f < 0.010 3 0. 010 7 f < 0. 035 4

5 0.03) 0.10 f

{7 f < 0.10 a ire estin.ated frequency of loss of of f site power due to sewe-e weather, f, is determined by the fc11owing equation:

f = (1.3 x IC~ Jhy + (b)h2 + (0.012)h3 + (c)h4 where b y = annual expectation of snowf all for the site, it inches, h2 = annual expectation of tornadoes (with wind speeds greater than or equal to 113 miles per hour) per square mile at the site, bD2.5 for sites with transmission lines on two or more rights-of-way spreading out in dif ferent directions from the switchyard if separated by at least 1/4 mile at dista1ces > 1 mile fron, the site switchyard, or b = 72.3 for sites with transmission lines on sne right-of-way.

l h annual expectation of storms at the site with wind velocities 3 = between 75 and 124 mph, and h4 = annual expectation of hurricanes at the site c = 0 if switchyard is not vulnerable to the e*fects of salt spray c = 0.76 if switchyard h vulnerable to the e"ects c' salt spray The annual expectation of snowf all, tornadoes, and storna may be obtained from National Weather Service data from the weather station nearest to the plant or by interpolation, if appropriate, between nearby weatter stations. The basis for the empirical equation for the frequency of loss of offsite power i

due to severe weather, f, is given in Appendix A to Reference 2.

t 24 l

l

Tatie 6 Definitions of Severe Weather Pecovery Groups (SWR)

SWR Grou: Definition f

1 Sites with en'a-:ed recovery (i.e. , sites that have the capability and procedures for restoring of fsite (non-emergency) ac power to the site within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> following a loss of offsite power due to severe ,

weather.)

4 2 Sites without enhanced recovery.

, 9 .

25

- . Table 7 De't.~itions of Extremely Severe Weather G es;s (ESW)

Annual expectation of storms at a site with wind velocities equal to or greater tha 125 miles ..

E5W Group

• per hour (e)**

~4

e < 3.) 10

~4 ~3

J,3 x 10 i e < 1 x 10 1

1 x 10'3 i e <3,3 x 10' 3

~2 J,3 x 10 ~3 i e < 1 x 10

~ -

~2 5 1 x 10 ie J

avind speeds in excess of 125 miles per hour are predominantly associated with hurricares. Plant sites with hurricane response procedures that place the unit int: safe shutdown conditions 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> prior to the expected LOOP caused by an approaching hurricane may use the next lowest ESW group.

• • The annual espectation of stores may be obtained from National Weather Service data from the weather station nearest to the plant, or by interpolatic , if appropriate, between nearby weather stations.

.. \

26 l

P

. l l

b h h l b db ,,,y 141 kV 8 34! kV unm v

'd .

ma  ::::.::::. c un.nu

1. %MM_ #_7(xs_si[n0"

1. %MM _ _ _ - .

pp un . . . _ - . .

GENERATOR if i! If if AUTou ATic qt 9 NC NC NO NO TRAN58LA l CLA551E NONSAF ET Y CW51t NONSAFETY

' I 4 l t_ AUTOW ATIC TR ANS F E ,_R l ,

l L 2 COP.1'C. '*J"LR - -)

1 l

l l

Figure 1. Sehesatic diagram of electrically independent transmission line . .

27

(

i l

• L L L L L -.

L L L L

' t E

us iv

- gav g a

L mw l

MMA nwa an ww AAAA AAhA y if if ff l t( If nowsArtiv no woatsArtty wo me me .

etass is class si Ma'h c6 ass it etAss it envisie% i civisiou atataatos oivision i isvision I I A 4 l

l L - f T t.!'if.!^_5 15" . d..

s,; , 3

. . . . J L. . . *fS"F!. tai _wgen .

c .

Figure 2. Schematic diagram of two switchyards electrically connected (one-unit site) l .

. . 98 28

(

l

i _

= ,

~

e a

b h b ,

'L b I

<  ; l 230 kV Sco kV M  ;

N )

MM 1

1 ,

MM M M MM MM MMM M  ;

MMMM l 9 if if if if II GENERATOR 2 il il NC WC Stht4ATOR1 l

WC WC TC WC TO WC10 NC TO NC sp045Af TTY MI MI WI WE to0NSAptTY UWil 1 UNIT 2 UNIT 1 UNIT 1 yNif 1

)

U Nif 2 CLAS& 11 CLA1118 CLAS518 CLAS$ 11 SUltL Sult$, SU$tl. Sults, le0 TC WO TO NOTo ho 10 OTHit! OTMtAS OTHEA5 OTHERA Figure 3. khematic diagram of two switchyards electrically connected (two unit site)

. Oe 29 e

e

• ' ~~c , v , , - - . , ~ , . _ _ , _ , _ _

• REFERENCES

1. U.S. Nuclear Regulatory Comission, "Reactor Safety Study,' WASH-1400, October 1975.

~

2. U.S. Nuclear Regulatory Comission, "Evaluation of Station Blacko'ut Acci-dents at Nuclear Power Plants, Technical Findings Related to Unresolved Saf ety Issue A-44 " NUREG-1032 September,1987.

3. U.S. Nuclear Regulatory Comission, "Collection and Evaluation of Complete and Partial 1.osses of Offsite Power at Nuclear Power Plants " NUREG/CR-3992 February 1985.

4. U.S. Nuclear Regulatory Comission, "Reliability of Emergency ac Power Sources at Nuclear Power Plants," NUREG/CR-2989, July 1983.

ad-

5. U.S. Nuclear Re9ulatory Comission, "Emergency Diesel Generator Operating Experience, 1981-1983." NUREG/CR-4347, Decee6er 1985.

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

7. Institute of Electrical and Electronics Engineers, "lEEE Standard for Preferred Power Supply for Nuclear Power Generating Stations," IEEE Std 765-1983.*

8. Institute of Electrical and Electronics Engineers, "IEEE Standard Criteria for Diesel Generator Units Applied as Standby Power Supplies for Nuclear Power Generating Stations,' IEEE Std 367-1984.*

9. Electric Power Research Institute, "The Reliability of Energency Diesel Generators at U. 5. Nuclear Power Plants", NSAC-108, September 1986, le. N O WC - % 180

~

isy.: IhN

= copies may be obtained from the Institute of Electrical and Electronics y,

- - - .f,,-

Engineers, 345 E. 47th Street, New York, NY 10017.

{'(, '

WIrj 30

VALUE/ IMPACT STATEMENT l i

A separate value/ impact statement was not prepared for this regulatory guide. The regulatory cnalysis prepared for the station bla:kout rule (NUREG-1109) provides the regulatory basis for this guide and examines the costs and benefits of the rule as implemented by the guide. A copy of MUREG-1109 is available for inspection and copying for a fee at the NRC Public Document Roor,1717 H Street NW., Washington, DC 20555. Free single ecpies may be obtainec upon written request to the Distributien Section, Room P-1304, Division of Ir. formation Support Services, U.S. Nuclear Regulatory Commission, Washingter., DC 20555.

s t

31

Appe . dix A Quality Assurance Guidance for her Safety Systems and Equipment  ;

1. General ,

This section provides the guidance for quality assurance (QA) activities l for non-safety systems and equipment for which credit is taken in the ~

resolution of Station Blackout (USI A-44) and for which there are no existing MRC QA requirements (e.g., Appendix B, Appendix R). Activities shall be implemented from among th:se listed in this section as appropriate, depending on whether the equipment is being added (NEW) or is existing.

The QA guidance provided herein explicitly is required for non-safety systems and equipment used to meet the requirements of 10 CFR 50.63 and ,,

not already covered by existing 10 CFR QA requirements. This guidance is not intended to require the formalized progre n or detailed record keepirs as required for safety-related equipment. Adlitionally, non-safety equipmentInstalled to meet the station blackt it rule must be implemented such that it does not degrade the existing safa .y-related systees. This is accomplished by making the non-safety equipme t independent to the extent practical free existing safety-related syn tems. The guidance provided,in this section outlines an acceptable Q program for non-safety equipment used for meeting the station blackout rule and not already covered by existing 10 CFR QA requirements.

32 e

.r.- -

, - , , - ,--7 -,.,r.. , _, y--x...-- ,,,-,,m,..,mm_-

._ _ _ . . _ _._ - ,_ ,.- -.s_,- ._..,--.e--.-..,-,----,-.-.-e -.

Appendix A (Cont'd)

~

2. QA Guidance for Non-Safety Equipment Not Covered By Other 10 CFR QA Requiremerts (1) Design Cortrol and Procurement Document Contrcl .,

Measures should be established to ensure that all design-related guidelires used in complying with 10 CFR 50.63 are included in design and procurement documents and that deviations therefrom are controlled.

(2) Instructions, Procedures and Drawings Inspections, tests, administrative controls and training necessary for compliance with 10 CFR 50.63 requirements should be prescribed

- by doewented instructions, procedures and drawings and should be 4

accomplished in accordance with these documents.

(3) Control of Purchased Material Equipment and Services Measures should be established to assure that purchased material, equipment and services confonn to the procurement documents.

(4) g etion A program for independent inspection of activities required to comply with 10 CFR 50.63 should be established and executed by or for, the organization performing the activity to verify confonnance i with documented installation drawings and test procedures for accomplishing the activities.

33

Appendix A (Cont'd)

(5) Test and Test Control .-

A test program should be established and implemented to assur.e that testing is perfonned and verified by inspection and audit to ~

demonstrate conformance with design and system readiness requirements. The tests should be perfonned in accordance wita written test procedures; test results should be properly evaluate and acted on.

(6) Inspection. Test and Operating Status _

~

keasures should be established to provide for the identification of .

items that have satisfactorily passed required tests and inspections.

(7) Nor,Informingitems Measures should be established to control items that do not conform to specified requirements to prevent inadvertent use or installation.

(8) Corrective Action Measures should be established to assure that conditions such as failures, malfunctions, deficiencies, deviations, defective components, and non-confonnances are promptly identified, reported and corrected.

(9) Records Records should be prepared and maintained to furnish evidence that l

the criteria anumerated above are being met for activitiet required to comply with 10 CFR 50.63.

34

Appendix A (Cont'd) l (10) Aceits Audits should be conducted and documented te verify compliance with ~

destgr, and procurement documents, instructions; procedures and dnvings; and inspection end test activities developed to domply with 10 CFR 50.63.

e 6

I 35 l

3 - -

I Appendix B i

Guidance Regarding System and Station Equipment Specifications Alternate Battery System (s)

Systeurs: Alternate AC Source (s)

Guidance:

Not Required, but the implementation Safety Italated Not Required. but the implementation surst be must be such that the existing class l

IEEE-279 such that the existing class IE electrical IE battery systems continue to meet systems continue to meet all appitcable all appiscable sarety related criterta.

i safety related criterta.

1 Not Required Not Required Redundancy l Not Required Diversity Required. See Section C.3.3.4 of this guide.

l i froni existing l EDGs Required if connected to Class IE buses. Separ- Required if connected to Class IE battery Independence systems. Separation to be provided by two from existing ation to be provided by two circuit breakers in

breakers in series (1 Class IE at the safety related series (1 Class IE at the Class IE bus Class IE bus and 1 non-Class IE).

systems and I non-Class IE).

Not Required Not Required Seismic i' Qual 1ffrations .'

? l Required, if normal cooling is lost for station Required. If nonnel cooling'is lost, for l Environmental blackout event only and not for accident condi- station blackout event only and not for Consideration accident conditions. Procedures should be tions. Procedures should be in place to effect j

the actions necessary to maintain acceptable in place to effect the actions necessary to environmental conditions for the required equip- maintain acceptable environmental conditions l' ment. See Section C.3.2.4 of this Guide, for the required equipment. See Section

' C.3.2.4 of this Guide.

36 i

Appendix 8(Contd]

Guidance Regarding System and Station Equipment Specifications (Cont'd1 Alternate Battery System (s)

Systems: Alternate AC Source (s)

Guidance:

Required to meet 10CFR50, 550.63 Capacity Required as specified in 10CFR50, 150.63 and Section C 3.3.1 of this Guide.

and Section C.3.3.4 of this Guide.

Required as indicated in Section Quality Required as indicated in Section C.3.5 C.3.5 of this Guide.

Assurance of this Guide.

Requirement to be applied consistent with Technical Requirement to be applied consisteet with the Interim Comunission Policy Statement Specification the Interim Commission Policy Statenient on Technical Specifications (Federal for Maintenance, on Technical Specifications f Federal Register Notice dated ).

Register Notice dated ) .

LCO, etc. _ _

Required to meet system functional Instrumentation Required to meet system functional requirements requirements and monitoring Not Required Single Failure Not Required Design should, to the extent prahticable, Cosuoon Cause Design shovid, to the extent practicable. minimize CCF between saf.ety related and Failure (CCF) e minimize CCF between safety related and non-safety related syst'nse ,

non-safety related systems 37 L- - -_- -_ _ __- - _ _ _ _ -

I i . .

Appendix 8(Contdl f

Guidance Regarding System and Station Equipment Specifications (Cont'd)

Water f nister source _

- Instrument Air Delivery System Systems: (Compeltssed Air System)

! (existing condensate (Alternate to auxiliary j

Guidance:

storage tank or alternatel feedwater system, RCIC system or condense _r l

holation makeup)

Not Required but the Not Required but the Safety Related Not Required but the implementation sesst be implementation must be l IEEE-279 1splementation must be such that the existing j

such that the existing such that the existing Class IE system continues Class IE systems continue Class IE systems continue to meet all applicable to meet all applicable to meet all applicable safety related criteria. safety related criteria.

safety related criteria.

Not Required Not Required Redundancy Not Required Not Required Not Required Diversity Not Required Ensure that the existing Ensure that the existing Independence Ensure that the existing safety functions are not safety functions are not safety functions are not From Safety comprwmised, including the compromised, including the Related Systems compromised, including the capability to isolate capab111ty to tsolate capability to isolate components, sub-systems, or components, sub-systems, or components, sub-systems, or piping, if required-piping, if required. pipir;g, if required.

Not Required Not Reqlitred Seismic Not Required Qualifications 38

• 2 Appendix 8(Contdl Guidance Regarding System and Station Equipment Specifications (Cont'd)

Water Water source Inttrument Air Delivery System Systems: (C W Mssed Air System)

[ existing condensate (Alternate to auxiliary Guidance:

storage tank or alternate) feedwater system, RCIC systete or isolation condenser makeup)

Required for station blackout Required for station blackout Environmental Rwired for station blackout event only and not for DEA event only and not for DBA Considerations event only and not for DBA conditions. Refer to Section conditions. Refer to Section condttions. Refer to Section C.3.2.4 of this Guide. Pro- C.3.2.4 of this Guide. Pro-C.3.2.4 of this Guide. Pro- cedures should be in place to cedures should be in place to cedures should be in olace to effect the actions necessary effect the actions necessary effect the actions necessary to maintain acceptable environ- to maintain acceptable envfron- to ciaf ntain acceptable environ mental conditions for the re- mental condt t tons for the re-mental conditions for the re- quired equfpment.

quired equipment. quired equipment.

Sufficient compressed The capacity to provide Capacity Capability to provide sufficient cooling water air to components, as sufficient amount of water flow to ensure that for core cooling in the event necessary, to ensure the core is cooled in of a Station Blackout for that the core is cooled and appropriate containment the event of a Station the specified duration to Diackout for the meet 10 CFR Part 50, 550.63 integrity is maintained for the specified duration of specified duration to meet and this regulatory guide. 10 CFR Part 50 and $50.63.

Station Blackout to meet 10 CFR Part 50, 550.63 *,

and this regulatory guide.

• Required as indicated Requir as indicated Quality Required as indicated in Section C.3.5 in Section C.3.5 in Section C.3.5 Assurance of this Guide. of this Guide.

of this Guide.

39 L -- - - - - - - - _ - - _ _ - _ _ _ _ _ _ __

Appendix 8(Contd)_

Guidance Regarding System and Station Equipment Specifications (Cont'd) water Water source Instrument Air Delivery 5ystem systems: (Comphssed Air System)

[ existing condensate (Alternate to auxiliary Guidance:

storage tank or alternate) feedwater systeni, HEIC systeer or isolation condenser makeup]

Requirement to be applied Requfrement to be applied Technical Requirgeant to be applied consistent with the Interim consistent with the Interim consistent with the Interim Cownission Policy Statement Specifications Commission Policy Statement Conanission Policy Statement for maintenance. on Technical Specifications on Technical Specifications surveillance LCO on Technical Specifications (Federal Register Notice _).

(Federal Register Notice _). (Federal Register Motice _).

etc.

Required to meet Required to meet Instrismentation Required to meet system functional system functional system functional and Monitoring requirements. requirements.

requirements.

Not Required Not Required Single Failure Not Required Design should, to the extent Design should, to the extent Design should, to the extent practicable, minimize CCF Common Cause practicable, minimize CCF practicable, minimize CCF between safety related and Failure (CCF) between safety related and between safety related and non-safety related systems. non-safety reldted systems.

non-safety related systems. ,e g .

40

Appendix 8 (Contdl

(;uidance Regarding System and Station Equipment Specifications (Cont'd)

Instrumentation, Controi RCS Makeup System Isolation Condenser Room Indications For Verif-System: (BWRs w?thout RCIC)

(PWRs & BWRs without RCIC) Ication of RCS Natural _

j Circulation (PWRs & BWRs Guidane : without RCICJ I

Not Required but the Not Required but the Safety Related Not Required but the implementation must be implementation must be implementation must be such that the existing 4

IEEE-279 such that the existing such that the existing Class IE systems continue Class IE systems continue Class IE systems continue to re t all applicable to meet all applicable to meet all applicable safety related criteria. safety related criteria.

safety related criteria.

l Not Required Not Required

! Redundancy Not Required Not Required Not Required

! Diversity Not Required i

1. Safety-grade isolation A mulfunction of this Independence 1. Safety grade isolation instrumentation and f devices required between devices between this monitoring system Frtun Safety system and existing Related Systems this RCS makeup system should not affect the and existing safety- safety-related systems, design safety function i

related makeup water systems. of any safety related

2. A malfunction of this instrumentation and

? 2. A malfunction of this non- non-safety related sys- monitoring , systems i

safety grade makeup system powered by onsite or should not affect the tema shoul6 not affect the offsite ac power design safety function of design safety function nf any safety-related systems. buses.

any safety-related systems.

Not Required Not Required Seismic Not Required Qualifications 41

1

! Appendix 8 (Contdl Guidance Regarding System and Station Equipment Specifications (Cont'd)

Instrumentation, Control il RC5 Rekoop System isolation Condenser Room Indications for Verif-

System

[BvRs Without RCIC]_ Ication of RC5 Natural (PWRs & Evns without RCIC)

, Circulation (PWRs & BWRs_

Guidance: without RCIC)

I i

Required for Station Blackout Required for Station Blackout i

Required for Station Blackout event only and not for DBA event only and not for DBA Environmental event only and not for 08A conditior.s if normal cooling Considerations conditions if normal cooling conditions if norinal cooling is lost. Refer to Section is lost. Refer to Section

' is lost. Refer to Section C.3.2.4 of this Guide. Pro- C.3.2.4 of this Guide. Pro-C,3.2.4 of this Guide. Pre- cedures should be in place to cedures should be in place to cedures should be in piece to effect the actions necessary effect the actions necessary i effect the actions necessary to mafstafn acceptable environ- to maintain acceptable environ-

! to maintain acceptable environ- mental conditions for the re-j mental cor.ditions for the re- mental conditions for the re- quired equipment.

l quired equipment.

quired equipment.

l Provfde sufficient capacity Provide sufficient instru-1 Capecity Sufficient RC5 makeup mentation, control room In-for decay heat removal. Dur- dications for parameters re-l required wth that core ing the specified duration

temperatures are maintained of station blackout the iso-quired for verification o' l at acceptably low values con- lation condenser pool side RCS natural circulation (

! sidering a loss of RCP water requires water makeup sys- ing the specified duration i inventory through a Postu- tem power =d by sources in- of Station Blackout.

l lated RCP seal failure during

! dependent from onsite and i

the sM1-ified duration of offsite ac buses.

i station blackout with a mini- ,.

? mum assumed RCP seal leakage *

' of 20 gym per RCP.

Required as indicated in Required as indicated in Required as indicated in Section C.3.5 of thfs l

Quality Section C.3.5 of this Section C.").5 of this Guide.

! Assurance Guide.

Guide.

42

Appendix 8 (Contdl Guidance Regardine System and Station Equipment Specifications (Coet'd)

Isolagon Conder::er Instrumentation, Control RCS Makeup System Room Indications For Verff-System: l_BWRs Without RCIC)

(PWRs & BWRs without RCIC) ication of RC5 Natural Guidance: Circulation (PWRs & BWRs without RCIC)

Requirwarnt to be applied Requirement to be app 11ed Technical Requirweent to be applied consistent with the Interim consistent with the Interim constatent with the Interim Cometssion Policy statement Specifications for Commission Policy Statement maintenanca. Commission Policy Statement on Technical SpectfIcations on Technfcai Speciffcat1ons on Technical Specifications survelliance. LCO. (Federal Register Notice (Federal Register Notice (Federal Register Notice dated ).

etc.

dated _ ). dated ).

Required to meet Required to meet Instruar_etation system functional and Monttoring system functional requirements. requirements.

Not Required Not Required Single Failure Not Required Design should, to the Design should, to the Common Cause Design should, to the extent practicable, extent practicable, Failure (CCF) extent practicable. afnfalze CCF between safety minimize CCF between safety minimize CCF between safety related and non-safety related and non-safety related and non-safety rvlated systems.

related systed .

r,1sted systems. .

I s

43 g_