Regulatory Guide 1.155

(Task SI 501-4) Station Blackout

ML003740034
Person / Time
Issue date:	08/31/1988
From:	Office of Nuclear Regulatory Research
To:
References
RG-1.155
Download: ML003740034 (24)

U.S. NUCLEAR REGULATORY COMMISSION August 1988 REGULATORY GUIDE

OFFICE OF NUCLEAR REGULATORY RESEARCH Reissued to correct REGULATORY GUIDE 1.155 Tables 1, (Task SI 5014) 5, and 6.

STATION BLACKOUT

A. INTRODUCTION

this regulatory guide provides quality assurance guidance for non-safety systems and equipment used to meet the Criterion 17, "Electric Power Systems," of Appendix requirements of § 50.63.

A, "General Design Criteria for Nuclear Power Plants,"

to 10 CFR Part 50, "Domestic Licensing of Production This guide describes a method acceptable to the NRC

and Utilization Facilities," includes a requirement that staff for complying with the Commission regulation that an onsite electric power system and an offsite electric requires nuclear power plants to be capable of coping power system be provided to permit functioning of with a station blackout for a specified duration. This structures, systems, and components important to safety. guide applies to all light-water-cooled nuclear power plants.

Criterion 1, "Quality Standards and Records," of Appendix A to 10CFR Part50 includes a requirement The Advisory Committee on Reactor Safeguards has for a quality assurance program to provide adequate been consulted concerning this guide and has concurred assurance that structures, systems, and components in the regulatory position.

important to safety will perform their safety functions.

Any information collection activities related to this Criterion 18, "Inspection and Testing of Electric regulatory guide are contained as requirements in the Power Systems," of Appendix A to 10 CFR Part 50 revision of 10 CFR Part 50 that provides the regulatory includes a requirement for appropriate periodic testing basis for this guide. The information collection require and inspection of electric power systems important to ments in Part 50 have been cleared under the Office of safety. Management and Budget Clearance No. 3150-0011.

The Commission has amended its regulations in 10

B. DISCUSSION

CFR Part 50. Paragraph (a), "Requirements," of § 50.63,

"Loss of All Alternating Current Power," requires that The term "station blackout" refers to the complete each light-water-cooled nuclear power plant be able to loss of alternating current electric power to the essential withstand and recover from a station blackout (i e,, and nonessential switchgear buses in a nuclear power loss of the offsite electric power system concurrent plant. Station blackout therefore involves the loss of with reactor trip and unavailability of the onsite emer offsite power concurrent with turbine trip and failure of gency ac electric power system) of a specified duration. the onsite emergency ac power system, but not the loss Section 50.63 requires that, for the station blackout of available ac power to buses fed by station batteries duration, the plant be capable of maintaining core through inverters or the loss of power from "alternate cooling and appropriate containment integrity. It also ac sources." Station blackout and alternate ac source identifies the factors that must be considered in specify are defined in § 50.2. Because many safety systems ing the station blackout duration. required for reactor core decay heat removal and con tainment heat removal are dependent on ac power, the Criteria 1 and 18 of Appendix A to 10 CFR Part 50 consequences of a station blackout could be severe. In apply-to safety-related equipment needed to cope-with sta .the event of a station blackout, the capability to cool tion blackout and other safety functions. Appendix A of the reactor core would be dependent on the availability USNRC REGULATORY GUIDES The guides are Issued in the following ten broad divisions:

Regulatory Guides are Issued to describe and make available to the public methods acceptable to the NRC staff of implementing 1. Power Reactors 6. Products specific parts of the Commission's regulations, to delineate tech- 2. Research and Test Reactors 7. Transportation niques used by the staff in evaluating specific problems or postu- 3. Fuels and Materials Facilities 8. Occupational Health iated accidents or to provide guidance to applicants. Regulatory 4. Environmental and Siting 9. Antitrust and Financial Review Guides are no substitutes for regulations, and compliance with 5. Materials and Plant Protection 10. General them is not required. Methods and solutions different from those set out in the guides will be acceptable if they provide a basis for the findings requisite to the issuance or continuance of a permit or Copies of issued guides may be purchased from the Government license by the Commission. Printing Office at the current GPO price. Information on current GPO prices may be obtained by contacting the Superintendent of This guide was Issued after consideration of comments received from Documents, U.S. Government Printing Office, Post Office Box the public. Comments and suggestions for Improvements in these 37082, Washington, DC 20013-7082, telephone (202)275-2060 or guides are encouraged at all times, And guides will be revised, as (202)275-2171.

appropriate, to accommodate comments and to reflect new informa tion or experience.

Issued guides may also be purchased from the National Technical Written comments may be submitted to the Rules and Procedures Information Service on a standing order basis. Details on this Branch, DRR, ADM, U.S. Nuclear Regulatory Commission, service may be obtained by writing NTIS, 5285 Port Royal Road, Washington, DC 20555. Springfield, VA 22161.

of systems that do not require ac power from the essential with design, operational, and environmental factors. Exist and nonessential switchgear buses and on the ability to ing standards and regulatory guides include specific design restore ac power in a timely manner. criteria and guidance on the independence of preferred (offsite) power circuits (see General Design Criterion 17, The concern about station blackout arose because of "Electric Power Systems," and Section 5.1.3 of Reference the accumulated experience regarding the reliability of ac 8) and the independence of and limiting interactions power supplies. Many operating plants have experienced a between diesel generator units at a nuclear station (see total loss of offsite electric power, and more occurrences General Design Criterion 17, Regulatory Guide 1.6, "Inde are expected in the future. In almost every one of these pendence Between Redundant Standby (Onsite) Power loss-of-offsite-power events, the onsite emergency ac power Sources and Between Their Distribution Systems," Regula supplies have been available immediately to supply the tory Guide 1.75, "Physical Independence of Electric power needed by vital safety equipment. However, in some Systems," and Reference 9). In developing the recommenda instances, one of the redundant emergencyac power supplies tions in this guide, the staff hasassumed that, by adhering to

-has been unavailable. In a few cases there has been a com such standards, licensees have minimized, to the extent plete loss of ac power, but during these events ac power was practical, single-point vulnerabilities in design and operation restored in a short time without any serious consequences. that could result in a loss of all offsite power or all onsite In addition, there have been numerous instances when emer emergency ac power.

gency diesel generators have failed to start and run in response to tests conducted at operating plants. Onsite emergency ac power system unavailability can be affected by outages resulting from testing and main The results of the Reactor Safety Study (Ref. 1) showed -tenance. Typically, this unavailability is about 0.007 that, for one of the two plants evaluated, a station blackout (Reference 5), which is small compared to the minimum event could be an important contributor to the total risk emergency diesel generator reliability specified in Regula from nuclear power plant accidents. Although this total risk tory Position 1.1 of this regulatory guide (ie., 0.95 or was found to be small, the relative importance of station 0.975 reliability per demand). However, in some cases blackout events was established. This finding and the outages due to maintenance can be a significant con accumulated diesel generator failure experience increased tributor to emergency diesel generator unavailability.

the concern about station blackout. This contribution can be kept low by having high-quality test and maintenance procedures and by scheduling regular In a Commission proceeding addressing station black diesel generator maintenance at times when the reactor is out, it was determined that the issue should be analyzed shut down. Also, limiting conditions for operation in the to identify preventive or mitigative measures that can or technical specifications are designed to limit the diesel should be taken. (See Florida Power & Light Company generator unavailability when the plant is operating. As (St. Lucie Nuclear Power Plant, Unit No. 2) ALAB-603, long as the unavailability due to testing and maintenance is

12 NRC 30 (1980); modified CLI-81-12, 13 NRC 838 not excessive, the maximum emergency diesel generator

(1981).) failure rates for each diesel generator specified in Regulatory Position 1.1 would result in acceptable overall reliability for The issue of station blackout involves the likelihood the emergency ac power system.

and duration of the loss of offsite power, the redundancy and reliability of onsite emergency ac power systems, Based on § 50.63, all licensees and applicants are and the potential for severe accident sequences after a required to assess the capability of their plants to maintain loss of all ac power. References 2 through 7 provide detailed adequate core cooling and appropriate containment integrity analyses of these topics. Based on risk studies performed to during a station blackout and to have procedures to cope date, the results indicate that estimated coremelt frequencies with such an event. This guide presents a method accept from station blackout vary considerably for different plants able to the NRC staff for determining the specified dura and could be a significant risk contributor for some plants. tion for which a plant should be able to withstand a station In order to reduce this risk, action should be taken to resolve blackout in accordance with these requirements. The the safety concern stemming from station blackout. The application of this method results in selecting a minimum issue is of concern for both PWRs and BWRs. acceptable station blackout duration capability from 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 plant's charac This guide primarily addresses the following three teristics with those factors that have been identified as areas: (1) maintaining highly reliable ac electric power significantly affecting the risk from station blackout. These systems, (2) developing procedures and training to restore factors include redundancy of the onsite emergency ac offsite and onsite emergency ac power should either one or power system (ie., the number of diesel generators available both become unavailable, and (3) ensuring that plants can for decay heat removal minus the number needed for decay cope with a station blackout for some period of time based heat removal), the reliability of onsite emergency ac power on the probability of occurrence of a station blackout at a sources (e.g., diesel generators), the frequency of loss of site as well as the capability for restoring ac power in a offsite power, and the probable time to restore offsite timely fashion for that site. power.

One factor that affects ac power system reliability Licensees may propose durations different from those is the vulnerability to common cause failures associated specified in this guide. The basis for alternative durations

1.155-2

would be predicated on plant-specific factors relating to the reliability of ac power systems such as those discussed Diesel Generators at U.S. Nuclear Power Plants"

in Reference 2. (Ref. 11), or equivalent.'

The information submitted to comply with § 2. Calculate the nuclear unit "average" EDG reliability

50.63 is also required to be incorporated in an update for the last 20, 50, and 100 demands by averaging to the FSAR in accordance with paragraph 50.71(e)(4), the results from step 1 above.

It is expected that the applicant or licensee will have available for review, as required, the analyses and related 3. Compare the calculated "average" nuclear unit informa tion supporting the submittal. EDG reliability from step 2 above against the following criteria:

Concurrent with the development of this regulatory guide, and consistent with discussions with Last 20 demands > 0.90 reliability the NRC

staff, the Nuclear Management and Resource Last 50 demands > 0.94 reliability Council (NUMARC) has developed guidelines and procedures Last 100 demands > 0.95 reliability for assessing station blackout coping capability and duration for light water reactors (NUMARC-8700, Ref. 4. If the EAC group is A, B, or C AND any of the

10). The NRC staff has reviewed these guidelines and three evaluation criteria in step 3 are met, the analysis methods and concludes that NUMARC-8700 nuclear unit may select an EDG reliability target provides guidance for conformance to § 50.63 that is of either 0.95 or 0.975 for determining the appli in large part identical to the guidance provided in this regulatory cable coping duration from Table 2.

guide. Table 1 of this regulatory guide provides a section by-section comparison between Regulatory Guide If the EAC group is D and any of the three

1.155 and NUMARC-8700. The use of NUMARC-8700 evaluation criteria in step 3 are met, the allowed is further discussed in Section C, Regulatory Position, EDG reliability target is 0.975.

of this guide.

5. If the EAC group is A, B, or C and NONE of the

C. REGULATORY POSITION

selection criteria in step 3 are met, an EDG

reliability level of 0.95 must be used for determin This regulatory guide describes a means acceptable ing the applicable coping duration from Table

2.

to the NRC staff for meeting the requirements Additionally, if the "averaged" nuclear unit EDG

of

§ 50.63 of 10 CFR Part 50. NUMARC-8700 (Ref. reliability is less than 0.90 based on the last

10) 20

also provides guidance acceptable to the staff demands, the acceptability of a coping duration for meet ing these requirements. Table I provides a cross-reference based on an EDG reliability of 0.95 from Table

2 to NUMARC-8700 and notes where the regulatory must be further justified.

guide takes precedence.

If the EAC group is D and NONE of the three

1. ONSITE EMERGENCY AC POWER SOURCES evaluation criteria in step 3 are met, the required (EMERGENCY DIESEL GENERATORS) coping duration (derived by using Table 2) should be increased to the next highest coping level (i.e.,

1.1 Emergency Diesel Generator Target Reliability Levels 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />).

The minimum emergency diesel generator 1.2 Reliability Program (EDG)

reliability should be targeted at 0.95 per demand for each EDG for plants in emergency ac (EAC) Groups The reliable operation of onsite emergency ac A, power B, and C and at 0.975 per demand for each sources should be ensured by a reliability EDG for program plants in EAC Group D (see Table 2). These designed to maintain and monitor the reliability reliability level levels will be considered minimum target reliabilities of each power source over time for assurance and that the each plant should have an EDG reliability selected reliability levels are being achieved. An program EDG

containing the principal elements, or their equivalent, reliability program would typically be composed of the outlined in Regulatory Position 1.2. Plants that following elements or activities (or their equivalent):

select a target EDG reliability of 0.975 will use the higher level 1. Individual EDG reliability target levels consistent as the target in their EDG reliability programs.

with the plant category and coping duration The EDG reliability for determining the selected from Table 2.

coping duration for a station blackout will be determined as 2. Surveillance testing and reliability monitoring follows:

programs designed to track EDG performance and

1. Calculate the most recent EDG reliability to support maintenance activities.

for each EDG based on the last 20, 50, and

100 IThis EDG reliability is not suitable demands using definitions and methodology for probabilistic risk in analyses for design basis accidents because of the differing Section 2 of NSAC-108, "Reliability of Emergency EDG start-rel/ability for such probabilistic requirement risk analyses.

that would be applicable

1.155-3

the probability of a station blackout at the site as

3. A maintenance program that ensures that the well as the capability for restoring ac power for that target EDG reliability is being achieved and that site. Each nuclear power plant has the capability to provides a capability for failure analysis and remove decay heat and maintain appropriate containment root-cause investigations. integrity without ac power for a limited period of time.

Regulatory Position3.2 provides guidance for determining

4. An information and data collection system that the length of time that a plant is actually able to cope services the elements of the reliability program and with a station blackout. If the plant's actual station that monitors achieved EDG reliability levels blackout capability is significantly less than the accept against target values. able minimum duration, modifications may be necessary to extend the plant's ability to cope with a station

5. Identified responsibilities for the major program blackout. Should plant modifications be necessary, elements and a management oversight program for Regulatory Position 3.3 provides guidance on making reviewing reliability levels being achieved and such modifications. Whether or not modifications are ensuring that the program is functioning properly. necessary, procedures and training for station blackout events should be provided according to the guidance in

1.3 Procedures for Restoring Emergency AC Power Regulatory Position 3.4.

Guidelines and procedures for actions to restore 3.1 Minimum Acceptable Station Blackout Duration emergency ac power when the emergency ac power Capability system is unavailable should be integrated with plant specific technical guidelines and emergency operating Each nuclear power plant should be able to withstand procedures developed using the emergency operating and recover from a station blackout lasting a specified procedure upgrade program established in response to minimum duration. The specified duration of station Supplement 1, "Requirements for Emergency Response blackout should be based on the following factors:

Capability" (Generic Letter No. 82-33),2 to NUREG-0737,

"Clarification of TMI Action Plan Requirements" 1. The redundancy of the onsite emergency ac (Ref. 12). power system (i.e., the number of power sources available minus the number needed for decay heat

2. OFFSITE POWER removal),

Procedures should include the actions necessary to3 2. The reliability of each of the onsite emergency ac sources restore offsite power and use nearby power power sources (e.g., diesel generator),

when offsite power is unavailable. As a minimum, the following potential causes for loss of offsite power 3. The expected frequency of loss of offsite power, should be considered: and Grid undervoltage and collapse 4. The probable time needed to restore offsite power.

Weather-induced power loss 4 Preferred power distribution system faults that A method for determining an acceptable minimum could result in the loss of normal power to essen station blackout duration capability as a function of tial switchgear buses the above site- and plant-related characteristics is given in Table 2. Tables 3 through 8 provide the necessary

3. ABILITY TO COPE WITH A STATION BLACKOUT detailed descriptions and definitions of the various factors used in Table 2. Table 3 identifies different levels The ability to cope with a station blackout for a of redundancy of the onsite emergency ac power system certain time provides additional "defense-in-depth should used to define the emergency ac power configuration both offsite and onsite emergency ac power systems fail groups in Table 2. Table 4 provides definitions of the concurrently. Regulatory Position 3.1 provides a method three offsite power design characteristic groups used in to determine an acceptable minimum time that a plant Table 2. The groups are defined according to various should. be able to cope.with a station blackout based on combinations of the following factors: (1) independence of offsite power (1), (2) severe weather (SW), (3) severe

2 Modifications or additions to generic technical guide blackout for lines that are necessary to deal with a station as identified deviations weather recovery (SWR), and (4) extremely severe the specific plant design should be in the plant-specific technical guidelines as required by weather (ESW). The definitions of the factors I, SW,

12) and outlined in Supplement 1 to NUREG-0737 (Ref.

Preparation of Emer SWR, and ESW are provided in Tables 5 through 8, NIREG-0899, "Guidelines for the13).

gency Operating Procedures ".(Ref. respectively. After identifying the appropriate groups from Tables 3 and 4 and the reliability level of the

3ThIs includes such items as nearby or onsite gas turbine onsite emergency ac power soUrces (determined in accor lenerators, portable generators, hydro generators, and ack-start fossil power plants. dance with Regulatory Position 1.1), Table 2 can be used to determine the acceptable minimum station

4 Includes such failures as the distribution system hard blackout duration capability for each plant.

ware, switching and maintenance errors, and lightning induced faults.

1.155-4

3.2 Evaluation of Plant-Specific Station Blackout environments if an assessment has been performed that Capability provides reasonable assurance that the required equip ment will remain operable.

Each nuclear power plant should be evaluated to determine its capability to withstand and recover from a 3.2.5. Consideration should be given to using available station blackout of the acceptable duration determined non-safety-related equipment, as well as safety-related for that plant (see Regulatory Position 3.1). The follow equipment, to cope with a station blackout provided ing considerations should be included when determining such equipment meets the recommendations of Regula the plant's capability to cope with a station blackout. tory Positions 3.3.3 and 3.3.4. Onsite or nearby alternate ac (AAC) power sources that are independent and

3.2.1. The evaluation should be performed assuming diverse from the normal Class IE emergency ac power that the station blackout event occurs while the reactor sources (e.g., gas turbine, separate diesel engine, steam is operating at 100% rated thermal power and has been supplies) will constitute an acceptable station blackout at this power level for at least 100 days. coping capability provided an analysis is performed that demonstrates the plant has this capability from the

3.2.2. The capability of all systems and components onset of station blackout until the AAC power source necessary to provide core cooling and decay heat or sources are started and lined up to operate all equip removal following a station blackout should be deter ment necessary to cope with station blackout for the mined, including station battery capacity, condensate required duration.

storage tank capacity, compressed air capacity, and instrumentation and control requirements. In general, equipment required to cope with a station blackout during 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

3.2.3. The ability to maintain adequate reactor the site. For equipment not located on the site, consid coolant system inventory to ensure that the core is eration should be given to its availability and accessibility cooled should be evaluated, taking into consideration in the time required, including consideration of weather shrinkage, leakage from pump seals, and inventory loss conditions likely to prevail during a loss of offsite from letdown or other normally open lines dependent power.

on ac power for isolation.

If the AAC source or sources meet the recommenda

3.2.4. The design adequacy and capability of equip tions of Section 3.3.5 and can be demonstrated by test ment needed to cope with a station blackout for the to be available to power the shutdown buses within 10

required duration and recovery period should be addressed minutes of the onset of station blackout, no coping and evaluated as appropriate for the associated environ analysis is required.

mental conditions. This should include consideration as appropriate of the following: 3.2.6. Consideration should be given to timely opera tor actions inside or outside the control room that

1. Potential failures of equipment necessary to cope would increase the length of time that the plant can with the station blackout, cope with a station blackout provided it can be demon strated that these actions can be carried out in a timely

2. Potential environmental effects on the operability fashion. For example, if station battery capacity is a and reliability of equipment necessary to cope limiting factor in coping with a station blackout, shed

-with the station blackout, including possible ding nonessential loads on the batteries could extend effects of fire protection systems, the time until the battery is depleted. If load shedding or other operator actions are considered, corresponding

3. Potential effects of other hazards, such as weather, procedures should be incorporated into the plant-specific on station blackout response equipment (e.g., technical guidelines and emergency operating procedures.

auxiliary equipment to operate onsite buses or to recover EDGs and other equipment as needed), 3.2.7. The ability to maintain "appropriate contain ment integrity" should be addressed. "Appropriate

4. Potential habitability concerns for those areas that containment integrity" for station blackout means that would require operator access during the station adequate containment integrity is ensured by providing blackout and recovery period. the capability, independent of the preferred and blacked out unit's onsite emergency ac power supplies, for valve Evaluations that have already been performed need position indication and closure for containment isolation not be duplicated. For example, if safety-related equip valves that may be in the open position at the onset of ment required during a total loss of ac power has been a station blackout. The following valves are excluded qualified to operate under environmental conditions from consideration:

exceeding those expected under a station blackout (e.g.,

loss of heating, ventilation, and air conditioning), addi 1. Valves normally locked closed during operation, tional analyses need not be performed. Equipment will be considered acceptable for station blackout temperature 2. Valves that fail closed on a loss of power,

1.155-5

3. Check valves, other means of control are required, it should be demonstrated that these steps can be carried out

4. Yalves in nonradioactive closed-loop systems not in a timely fashion, and expected to be breached in a station blackout (this does not include lines that communicate 2. If the system must operate within 10 minutes of a directly with containment atmosphere), and loss of all ac power, it should be capable of being actuated from the control room.

5. Valves of less than 3-inch nominal diameter.

3.3.5. If an AAC power source is selected specifically

3.3 Modifications To Cope with Station Blackout for satisfying the requirements for station blackout, the design should meet the following criteria:

If .the plant's station blackout capability, as deter mined according to the guidance in Regulatory Position 1. The AAC power source should not normally

3.2, is significintly less than the minimum acceptable be directly connected to the preferred or the plant-specific station blackout duration (as developed blacked-out unit's onsite emergency ac power according to Regulatory Position 3.1 or as justified by system.

the licensee or applicant on some other basis and accepted by the staf), modifications to the plant may 2. There should be a minimum potential for common be necessary to extend the time the plant is able to -cause failure with the preferred or the blacked-out cope with a station blackout. If modifications are unit's onsite emergency ac power sources. No needed, the following items should be considered: single-point vulnerability should exist whereby a weather-related event or single active failure could

3.3.1. If, after considering load shedding to extend disable any portion of the blacked-out unit's onsite the time until battery depletion, battery capacity must emergency ac power sources or the preferred power be extended further to 'meet the station blackout dura sources and simultaneously fail the AAC power tion recommended in Regulatory Position3.1, it is source.

considered acceptable either to add batteries or to add a charging system for the existing batteries that is inde 3. The AAC power source should be available in a pendent of both the offsite and the blacked-out unit's timely manner after the onset of station blackout onsite emergency ac power systems, such as a dedicated and have provisions to be manually connected to diesel generator. one or all of the redundant safety buses as required.

The time required for making this equipment

3.3.2. If the capacity of the condensate storage tank available should not be more than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> as is not sufficient to remove decay heat for the station demonstrated by test. If the AAC power source blackout duration recommended in Regulatory Position 3.1, can be demonstrated by test to be available to a system meeting the requirements of Regulatory Posi power the shutdown buses within 10 minutes of tion 3.5 to resupply the tank from an alternative water the onset of station blackout, no coping analysis source is an acceptable means to increase its capacity is required.

provided any power source necessary to provide addi tional water is independent of both the offsite and the 4. The AAC power source should have sufficient blacked-out unit's onsite emergency ac power systems. capacity to operate the systems necessary for coping with a station blackout for the time required

3.3.3. If the compressed air capacity is not sufficient to bring and maintain the plant in safe shutdown.

to remove decay heat and to maintain appropriate containment integrity for the station blackout duration 5. The AAC power system should be inspected, recommended in Regulatory Position 3.1, a system to maintained, and tested periodically to demonstrate provide sufficient capacity from an alternative source operability and reliability. The reliability of the that meets Regulatory Position 3.5 is an acceptable AAC power system should meet or exceed 95 per means to increase the air capacity provided any power cent as determined in accordance with NSAC-108 source necessary to provide additional air is independent (Ref. 11) or equivalent methodology.

of both the offsite and the blacked-out unit's onsite emergency ac power systems. An AAC power source serving a multiple-unit site where onsite emergency ac sources are not shared

3.3.4. If a system is required for primary coolant between units should have, as a minimum, the capacity charging and makeup, reactor coolant pump seal cooling and capability for coping with station blackout in any or injection, decay heat removal, or maintaining appro of the units.

priate containment integrity specifically to meet the station blackout duration recommended in Regulatory At sites where onsite emergency sources are shared Position 3.1, the following criteria should be met: between units, the AAC power sources should have the capacity and capability to ensure that all units can be

1. The system should be capable of being actuated brought to and maintained in safe shutdown (i.e., those and controlled from the control room, or if plant conditions defined in plant technical specifications

1.155-6

as Hot Standby or Hot Shutdown, as appropriate). Plants Position 3.1 and to restore normal long-term core cooling/

have the option of maintaining the RCS at normal decay heat removal once ac power is restored.

operating temperatures or at reduced temperatures.

3.5 Quality Assurance and Specification Guidance for Plants that have more than the required redundancy Station Blackout Equipment That Is Not Safety Related of emergency ac sources for loss-of-offsite-power condi tions, on a per nuclear unit basis, may use one of the existing emergency sources as an AAC power source Appendices A and B provide guidance on quality assurance provided it meets the applicable criteria for an AAC (QA) activities and specifications respectively for non-safety related equipment used to meet the requirements of § 50.63 source. Additionally, emergency diesel generators with

1-out-of-2-shared and 2-out-of-3-shared ac power configura and not already covered by existing QA requirements in tions may not be used as AAC power sources. Appendix B or R of Part 50. Appropriate activities should be implemented from among those listed in these appen

3.3.6. If a system or component is added specifically dices depending on whether the non-safety equipment is being added (new) or is existing. This QA guidance is to meet the recommendations on station blackout duration in Regulatory Position 3.1, system walk downs applicable to non-safety systems and equipment for meet ing the requirements' of " 50.63 of )l0 CFR Part 50.

and initial tests of new or modified, systems or critical components should be performed to verify that the The guidance on QA and specifications incorporates a modifications were performed properly. Failures of lesser degree of stringency by eliminating requirements for added components that may be vulnerable to internal or involvement of parties outside the normal line organization.

external hazards within the design basis (e.g., seismic NRC inspections will focus on the implementation and effectiveness of the quality controls 'described in Appen events) should not affect the operation of systems required for the design basis accident. dices A and B. Additionally, the equipment installed to meet the station blackout rule must be implemented such that it does not degrade the existing safety-related

3.3.7. A system or component added specifically to meet the recommendations on station blackout duration systems. This is to be accomplished by making the non safety-related equipment as independent as practicable in Regulatory Position 3.1 should be inspected, main tained, and tested periodically to demonstrate equipment from existing safety-related systems. The non-safety operability and reliability. systems identified in Appendix B are acceptable to the NRC staff for responding to a station blackout.

3.4 Procedures and Training To Cope with Station Blackout

D. IMPLEMENTATION

Proceduress and training should include all operator The purpose of this section is to provide information actions necessary to cope with a station blackout for at to applicants and licensees regarding the NRC staffs plans least the duration determined according to Regulatory for using this regulatory guide. Except in those cases in which the applicant or licensee proposes an acceptable alternative method for complying with specified portions of the Commission's regulations, the method described in SProcedures should be integrated with plant-specific this guide may be used in the evaluation of submittals by technical guidelines and emergency operating procedures developed the emergency operating procedure up usingestablished applicants for construction permits and operating licenses grade program in response to Supplement 1 of (as appropriate) and will be used to evaluate licensees who NUREG-0737 (Ref. 12). The task analysis -portion of the emergency operating procedure upgrade program shoulda are required to comply with § 50.63, "Loss of All Alter include an analysis of instrumentation adequacy during nating Current Power," of 10 CFR Part 50.

station blackout.

1.155-7

TABLE 1 CROSS-REFERENCE BETWEEN REGULATORY

GUIDE 1.155 AND NUMARC-8700

Regulatory Position in R.G. 1.155 Section in 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

3.2.2 2.9, 7.2.1, 7.2.2, 7.2.3

3.2.3 2.5

3.2.4 2.7, 4.2.1,4.2.2, 7.2.4, Appendices E and F

3.2.5 7.1.1, 7.1.2, Appendices B and C

3.2.6 4.2.1, 4.3.1, 7.2.1, 7.2.2, 7.2.3

3.2.7 2.10, 7.2.5

3.3.1 7.2.2

3.3.2 7.2.1

3.3.3 7.2.3

3.3.4 2.5

3.3.5 2.3.1, 7.1.1, 7.1.2, Appendices A,

B, and C

3.3.6 None (Use Regulatory Guide 1.155)

3.3.7 4 2

. .1(12),4.3.1(12), Appendices A

and B

3.4 4

3.5 None (Use Regulatory Guide 1.155)

Appendix A None (Use Regulatory Guide 1.155)

Appendix B None (Use Regulatory Guide 1.155

1.155-8

TABLE 2 ACCEPTABLE STATION BLACKOUT DURATION CAPABILITY (HOURS)a Emergency AC Power Configuration Groupb Unit "Average" EDG Reliabilityc Offsite Power Designd 0.975 0.95 0.975 0.95 0.975 0.95 0.975 Characteristic Groupd P1 2 2 4 4 4 4 4 P2 4 4 4 4 4 8 8 P3 4 8 4 8 8 16 8 aVariations from these times will be considered by the staff if justification, including a cost-benefit analysis, is provided by the licensee. The methodology and sensitivity studies presented in NUREG-1032 (Ref. 2) are acceptable for use in this justification.

bsee Table 3 to determine emergency ac power configuration group.

cSee Regulatory Position 1. 1.

dSee Table 4 to determine groups P1, P2, and P3.

1.155-9

TABLE 3 EMERGENCY AC POWER CONFIGURATION GROUPSa EAC Power Number of EAC Power Sources Configuration Number of EAC Required To Operate AC-Powered Group Power Sourcesb Decay Heat Removal Systemsc A 3 d 1

4 '1 B 4 2

5 2 C d

23e1 1 D 2f1

3 2

4 3

5 3 aSpecial-purpose dedicated diesel generators, such as those associated with high-pressure core spray systems at some BWRs, are not counted in the determination of EAC power configuration groups.

1 b1 f any of the EAC power sources are shared among units at a multi-unit site, this is the total number of shared and dedicated sources for those units at the site.

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

dFor EAC power sources not shared with other units.

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

fFor shared EAC power sources in which each diesel generator is capable of providing ac power to more than one unit at a site concurrently.

1.155-10

TABLE 4 OFFSITE POWER DESIGN CHARACTERISTIC GROUPS

Group Offsite Power Design Characteristics Sites that have any combination of the following factors:

,a Swb SWRc ESWd P1 lor2 lor2 lor2 lor2

1 or2 1 1 or2 3

1 or2 3 1 1 or2 P2 All other sites not in PI 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 procedures to recover ac power from reliable alternative (nonemergency) ac power sources within approximately one-half hour following a grid failure.

or Sites that have any combination of the following factors:

P3 I SW SWR ESW

Any 1 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

1 or2 3 2 4

3 3 2 3 or4 aSee Table 5 for definitions of independence of offsite power (I) groups.

bSee Table 6 for definitions of severe weather (SW) groups.

cSee Table 7 for definitions of severe weather recovery (SWR) groups.

dSee Table 8 for definitions of extremely severe weather (ESW) groups.

1.155-11

TABLE 5 DEFINITIONS OF INDEPENDENCE OF OFFSITE POWER GROUPS

Category 23

1. All offsite power sources are L.a. All offsite power sources are connected to the connected to the plant plant through one switchyard.

through two or more switchyards or separate OR

incoming transmission

1. Independence of offsite lines, but at least one of 1.b. All offsite power sources are connected to the power sources the ac sources is electrically plant through two or more switchyards, and independent of the others. the switchyards are electrically connected.

(The independent 69-kV (The 345- and 138-kV switchyards in Figures line in Figure 1 is 2 and 3 represent this design feature.)

representative of this design feature.)

OR AND AND

2. Automatic and manual 2.a. After loss of the normal ac 2.a. After loss of the normal 2.a. If the normal transfer schemes for the source, ac power source, there is source of ac Class 1E buses when the an automatic transfer of power fails, there normal source of ac power (1) There is an automatic all safe-shutdown buses are no automatic fails and when the back- transfer of all safe- to one preferred alter- transfers and up sources of offsite shutdown buses to nate power source. If one or more power fail. a separate preferred this source fails, there manual transfers alternate power source. may be one or more of all safe-shut a. The normal source of manual transfers of down buses ac power is assumed (2) There is an automatic power source to the to preferred or to be the unit main transfer of all safe- remaining preferred alternate off generator. shutdown buses to one or alternate offsite site power preferred power source. power sources, sources.

If this preferred power source fails, there is OR

another automatic transfer to the There is one auto remaining matic transfer preferred power and no manual sources or to alter- transfer of all nate offsite power safe-shutdown source. buses to one preferred or one alternate offsite power source.

OR OR

b. If the Class 1E buses 2.b. Each safe-shutdown bus is 2.b. The safe-shutdown buses are normally aligned are normally designed normally connected to a to the same preferred power source with to be connected to the separate preferred alter- either an automatic or manual transfer to the preferred or alternate nate power source with remaining preferred or alternate ac power power sources. automatic or manual source.

transfer capability between the preferred or alternate sources.

t-

1.155-12

TABLE 6 DEFINITIONS OF SEVERE WEATHER (SW) GROUPS

Estimated Frequency of Loss of Offsite Power Due to SW Group Severe Weather, f (per Site-Year)*

1 f <3.3 x 10-3

2 3.3x10 3 <f< lx10-2

3 1x10-2 <f<3.3x10- 2

1

4 3.3x10-2 <f< 1xl0"

5 1x10"1 <f

• The estimated frequency of loss of offsite power due to severe weather, f, is determined by the following equation:

f = (1.3 x 10"4)hl + (b)h 2 + (0.012)h 3 + (c)h 4 where h 1 = annual expectation of snowfall for the site, in inches h2 = annual expectation of tornadoes (with wind speeds greater than or equal to 113 miles per hour) per square mile at the site b = 12.5 for sites with transmission lines on two or more rights of-way spreading out in different directions from the switch yard, or b = 72.3 for sites with transmission lines on one fight-of-way h3= annual expectation of storms at the site with wind velocities between 75 and 124 mph 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 is vulnerable to the effects of salt spray The annual expectation of snowfall, tornadoes, and storms may be obtained from National Weather Service data from the weather station nearest to the plant or by interpolation, if appropriate, between nearby weather stations.

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

1.155-13

TABLE 7 DEFINITIONS OF SEVERE WEATHER RECOVERY (SWR) GROUPS

SWR Group Definition I Sites with enhanced recovery (i.e., sites that have the capability and procedures for restor ing offsite (nonemergency) 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).

2 Sites without enhanced recovery.

TABLE 8 DEFINITIONS OF EXTREMELY SEVERE WEATHER (ESW) GROUPS

Annual expectation of storms at a site with wind velocities equal to or greater than 125 miles per ESW Group hour (e)*

1 e <3.3x 10-4

4

2 3.3x 10- <e<1x 10-3

3 1x10-3 <e<3.3x10-3

3

4 3.3x10- <e <1x10-2

5 1 x 10-2 <e

• The annual expectation of storms may be obtained from National Weather Service data from the weather station nearest to the plant or by interpola tion, if appropriate, between nearby weather stations.

--L-

1.155-14

69 kV

7AUTOMATIC

NM U UMPI ILI

UI

TRANSFER

MAIN

GENERATOR NC NC NO NO TRANSFER

CLASS 1E NONSAFETY CLASS 1E NONSAFETY

I .. AUTOMATIC TRANSFER4 4 IL AUTOMATIC TRANSFER _. I

Figure 1. Schematic Diagram of Electrically Independent Transmission Line

1.155-15

4 I ttt4t

345 kV 138 kV

C

MAIN

GENERATOR

WNC

Att CLASS IE

NC

CLASS IE

NONSAFETY NO

CLASS 1E

NONSAFETY NO

CLASS I E

DIVISION I DIVISION 2 DIVISION I DIVISION 2 I I I 4 IIL AUTOMATIC TRANSFER I

-AUTOMATIC TRANSFER J

Figure 2. Schematic Diagram of Two Switchyards Electrically Connected (One-Unit Site)

t t +

500 kV

230 kV

td'V

MM MM I

GENERATOR 2 NC NC NC TO NC TO NC TO NC TO NC NC GENERATOR I

NONSAFETY SOME SOME SOME SOME NONSAFETY

UNIT 2 UNIT 2 UNIT 2 UNIT I UNIT I UNIT 1 CLASS I E CLASS 1E CLASS I E CLASS I E

BUSES, BUSES, BUSES, BUSES,

NO TO NO TO NO TO NO TO

OTHERS OTHERS OTHERS OTHERS

Figure 3. Schematic Diagram of Two Switchyards Electrically Connected (Two-Unit Site)

1.155-16

REFERENCES

1. U.S. Nuclear Regulatory Commission, "Reactor 8. Institute of Electrical and Electronics Engineers, Safety Study," WASH-1400, October 1975.1 "IEEE Standard for Preferred Power Supply for Nuclear Power Generating Stations," IEEE Std 2. U.S. Nuclear Regulatory Commission, "Evaluation of 765-1983, June 1983.2 Station Blackout Accidents at Nuclear Power Plants, Technical Findings Related to Unresolved Safety 9. Institute of Electrical and Electronics Engineers, Issue A-44," NUREG-1032, June 1988.1 "IEEE Standard Criteria for Diesel-Generator Units Applied as Standby Power Supplies for Nuclear Power Generating Stations," IEEE Std 387-1984.

3. A. M. Rubin, "Regulatory/Backfit Analysis for the June 1984.2 Resolution of Unresolved Safety Issue A-44, Station Blackout," U.S. Nuclear Regulatory Commission, 10. Nuclear Management and Resources Council, "Guide NUREG-1109, June 1988.1 lines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors,"

4. U.S. Nuclear Regulatory Commission, "Collection NUMARC-8700, November 1987.3 and Evaluation of Complete and Partial Losses of Offsite Power at Nuclear Power Plants," NUREG/ 11. Electric Power Research institute, "Reliability of CR-3992 (ORNL/TM-9384), February 1985.1 Emergency Diesel Generators at U.S. Nuclear Power Plants," NSAC-108, September 1986.4

5. U.S. Nuclear Regulatory Commission, "Reliability of Emergency AC Power System at Nuclear Power 12. U.S. Nuclear Regulatory Commission, "Clarification of Plants," NUREG/CR-2989 (ORNL/TM-8545), July TMI Action Plan Requirements: Requirements for

1983.1 Emergency Response Capability" (Generic Letter 82-33), Supplement 1 to NUREG-0737, January 1983.1

6. U.S. Nuclear Regulatory Commission, "Emergency Diesel Generator Operating Experience, 1981-1983," 13. U.S. Nuclear Regulatory Commission, "Guidelines for NUREG/CR-4347 (ORNL/TM-9739), December 1985.1 the Preparation of Emergency Operating Procedures,"

NUREG-0899, August 1982.1

7. U.S. Nuclear Regulatory Commission, "Station Black out Accident Analyses (Part of NRC Task Action 2 Copies may be obtained from the Institute of Plan A-44)," NUREG/CR-3226 (SAND82-2450), May Electrical and Electronics Engineers Service Center, 445 Hoes Lane,

1983.1 P.O. Box 1331, Piscataway, NJ 08855.

3 Copies may be obtained from the Nuclear Management and Resources Council, 1776 Eye Street NW., Washington,

1NRC publications may be obtained from the Super DC 20006.

intendent of Documents, U.S. Government Printing Office, 4 Post Office Box 37082, Washington, DC 20013-7082; or Copies may be obtained from the Electric Power from the National Technical Information Service, Spring Research Institute, Research Reports Center, P.O. Box field, VA 22161. 50490, Palo Alto, CA 94303.

1.155-17

APPENDIX A

QUALITY ASSURANCE GUIDANCE FOR NON-SAFETY SYSTEMS AND EQUIPMENT

The QA guidance provided here is applicable to non tion drawings and test procedures for accomplishing the safety systems and equipment used to meet the requirements activities.

of § 50.63 and not already explicitly covered by existing QA requirements in 10 CFR Part 50 in Appendix B or R. S. Testing and Test Control Additionally, non-safety equipment installed to meet the station blackout rule must be implemented so that it does A test program should be established and implemented not degrade the existing safety-related systems. This is to ensure that testing is performed and verified by inspec accomplished by making the non-safety equipment as tion and audit to demonstrate conformance with design independent as practicable from existing safety-related and system readiness requirements. The tests should be systems. The guidance provided in this section outlines an performed in accordance with written test procedures; test acceptable QA program for non-safety equipment used for results should be properly evaluated and acted on.

meeting the station blackout rule and not already covered by existing QA requirements. Activities should be imple 6. Inspection, Test, and Operating Status mented from this section as appropriate, depending on whether the equipment is being added (new) or is existing. Measures should be established to identify items that have satisfactorily passed required tests and inspections.

1. Design Control and Procurement Document Control

7. Nonconforming Items Measures should be established to ensure that all design related guidelines used in complying with § 50.63 are Measures should be established to control items that do included in design and procurement documents, and not conform to specified requirements to prevent inadvertent that deviations therefrom are controlled. use or installation.

2. Instructions, Procedures, and Drawings 8. Corrective Action Inspections, tests, administrative controls, and training necessary for compliance with § 50.63 should be prescribed Measures should be established to ensure that failures, malfunctions, deficiencies, deviations, defective components,

.L

by documented instructions, procedures, and drawings and and nonconformances are promptly identified, reported, should be accomplished in accordance with these documents. and corrected.

3. Control of Purchased Material, Equipment, and Services 9. Records Measures should be established to ensure that purchased Records should be prepared and maintained to furnish material, equipment, and services conform to the procure evidence that the criteria enumerated above are being met ment documents. for activities required to comply with § 50.63.

4. Inspection 10. Audits A program for independent inspection of activities Audits should be conducted and documented to verify required to comply with § 50.63 should be established compliance with design and procurement documents, and executed by (or for) the organization performing the instructions, procedures, drawings, and inspection and test activity to verify conformance with documented installa- activities developed to comply with § 50.63.

1i

1.155-18

4

APPENDIX B

GUIDANCE REGARDING SYSTEM AND STATION EQUIPMENT SPECIFICATIONS

Alternate AC Sources Alternate Battery Systems Safety-Related Not required, but the existing Class 1E electrical Not required, but the existing Class I E battery Equipment systems must continue to meet all applicable systems must continue to meet all applicable (Compliance with safety-related criteria. safety-related criteria.

IEEE-279)

Redundancy Not required. Not required.

Diversity See Regulatory Position 3.3.5 of this guide. Not required.

from Existing EDGs .1'

Independence Required if connected to Class 1E buses. Separa Required if connected to Class 1E battery from Existing tion to be provided by 2 circuit breakers in systems. Separation to be provided by 2 circuit Safety-Related series (1 Class 1E at the Class 1E bus and breakers in series (1 Class 1E at the Class 1E

Systems 1 non-Class 1E). bus and 1 non-Class 1E).

Seismic Not required. Not required.

Qualification Environmental If normal cooling is lost, needed for station If normal cooling is lost, needed for station Consideration blackout event only and not for design basis blackout event only and not for accident condi accident (DBA) conditions. Procedures should tions. Procedures should be in place to effect be in place to effect the actions necessary to the actions necessary to maintain acceptable maintain acceptable environmental conditions environmental conditions for the required for the required equipment. See Regulatory equipment. See Regulatory Position 3.2.4.

Position 3.2.4.

Capacity Specified in § 50.63 and Regulatory Position Specified in § 50.63 and Regulatory Position

3.3.5. 3.3.1.

Quality Indicated in Regulatory Position 3.5. Indicated in Regulatory Position 3.5.

Assurance Technical Should be consistent with the Interim Commission Should be consistent with the Interim Com Specification Policy Statement on Technical Specifications mission Policy Statement on Technical for Maintenance, (Federal Register Notice 52 FR 3789) as applicable. Specifications (Federal Register Notice Limiting Condi 52 FR 3789) as applicable.

tion, FSAR, etc.

Instrumentation Must meet system functional requirements. Must meet system functional requirements.

and Monitoring Single Failure Not required. Not required.

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

1.155-19

APPENDIX B (Continued)

Water Delivery System (Alternative to Auxiliary Water Source (Existing Feedwater System, RCIC

Condensate Storage Tank Instrument Air System, or Isolation or Alternative) (Compressed Air System) Condenser Makeup)

Safety-Related Not required, but the existing Not required, but the existing Not required, but the existing Equipment Class 1E systems must continue Class 1E systems must continue Class 1E systems must continue (Compliance with to meet all applicable safety to meet all applicable safety to meet all applicable safety IEEE-279) related criteria. related criteria. related criteria.

Redundancy Not required. Not required. Not required.

Diversity Not required. Not required. Not required.

Independence Ensure that the existing safety Ensure that the existing safety Ensure that the existing safety from Safety functions are not compromised, functions are not compromised, functions are not compromised, Related Systems including the capability to including the capability to including the capability to isolate components, subsystems, isolate components, subsystems, isolate components, subsystems, or piping, if necessary. or piping, if necessary. or piping, if necessary.

Seismic Not required. Not required. Not required.

Qualification Environmental Need for station blackout Needed for station blackout Needed for station blackout Consideration event only and not for DBA event only and not for DBA event only and not for DBA

conditions. See Regulatory conditions. See Regulatory conditions. See Regulatory Position 3.2.4. Procedures Position 3.2.4. Procedures Position 3.2.4. Procedures should be in place to effect should be in place to effect should be in place to effect the actions necessary to the actions necessary to the actions necessary to maintain acceptable maintain acceptable maintain acceptable environmental conditions environmental conditions environmental conditions for required equipment. for required equipment. for required equipment.

Capacity Capability to provide sufficient Sufficient compressed air to The capacity to provide suffi water for core cooling in the components, as necessary, to cient cooling water flow to event of a station blackout for ensure that the core is cooled ensure that the core is cooled the specified duration to meet and appropriate containment in the event of a station black

§ 50.63 and this regulatory integrity is maintained for the out for the specified duration guide. specified duration of station to meet § 50.63 and this blackout to meet § 50.63 and regulatory guide.

this regulatory guide.

Quality As indicated in Regulatory As indicated in Regulatory As indicated in Regulatory Assurance Position 3.5. Position 3.5. Position 3.5.

Technical Specifica Should be consistent with the Should be consistent with the Should be consistent with the tions for Mainte Interim Commission Policy Interim Commission Policy Interim Commission Policy nance, Surveillance, Statement on Technical Statement on Technical Statement on Technical Limiting Condition, Specifications (Federal Specifications (Federal Specifications (Federal FSAR, etc. Register Notice 52 FR 3789) Register Notice 52 FR 3789) Register Notice 52 FR 3789)

as applicable. as applicable. as applicable.

Instrumentation Must meet system functional Must meet system functional Must meet system functional and Monitoring requirements. requirements. requirements.

Single Failure Not required. Not required. Not required.

1.155-20

APPENDIX B (Continued)

Water Delivery System (Alternative to Auxiliary Water Source (Existing Feedwater System, RCIC

Condensate Storage Tank Instrument Air System, or Isolation or Alternative) (Compressed Air System) Condenser Makeup)

Common Cause Design should, to the extent Design should, to the extent Design should, to the extent Failure (CCF) practicable, minimize CCF practicable, minimize CCF practicable, minimize CCF

between safety-related and between safety-related and between safety-related and non-safety-related systems. non-safety-related systems. non-safety-related systems.

1.155-21

APPENDIX B (Continued)

Instrumentation and Control Room Indications for Verifica RCS Makeup System Isolation Condenser tion of RCS Natural Circulation (PWRs and BWRs Without RCIC) (BWRs Without RCIC) (PWRs and BWRs Without RCIC)

Safety-Related Not required, but the existing Not required, but the existing Not required, but the existing Equipment (Com Class 1E systems must continue Class 1E systems must continue Class 1E systems must continue pliance with to meet all applicable safety to meet all applicable safety to meet all applicable safety IEEE-279) related criteria. related criteria. related criteria.

Redundancy Not required. Not required. Not required.

Diversity Not required. Not required. Not required.

Independence 1. Safety-grade isolation 1. Safety-grade isolation A malfunction of this instru from Safety devices required between devices required between mentation and monitoring Related Systems this RCS makeup system this system and existing system should not affect the and existing safety-related safety-related systems. design safety function of any makeup water systems. safety-related instrumentation and monitoring systems

2. A malfunction of this non 2. A malfunction of this powered by onsite or offsite safety-grade makeup system non-safety-related system ac power buses.

should not affect the design should not affect the safety function of any safety design safety function of related systems. any safety-related systems.

Seismic Not required. Not required. Not required.

Qualification Environmental Needed for station blackout Needed for station blackout Needed for station blackout Consideration event only and not for DBA event only and not for DBA event only and not for DBA

conditions if normal cooling is conditions if normal cooling is conditions if normal cooling is lost. See Regulatory Position lost. See Regulatory Position lost. See Regulatory Position

3.2.4. Procedures should be in 3.2.4. Procedures should be in 3.2.4. Procedures should be in place to effect the actions place to effect the actions place to effect the actions necessary to maintain accept necessary to maintain accept necessary to maintain accept able environmental conditions able environmental conditions able environmental conditions for the required equipment. for the required equipment. for the required equipment.

Capacity Sufficient RCS makeup so that Provide sufficient capacity for Provide sufficient instrumenta core temperatures are maintained decay heat removal During tion and control room indica at acceptably low values con the specified duration of tions for parameters required sidering a loss of RCP water station blackout, the isolation for verification of RCS natural inventory through a postulated condenser pool side requires circulation during the specified RCP seal failure during the a water makeup system duration of station blackout.

specified duration of station powered by sources inde blackout, with a minimum pendent from onsite and assumed RCP seal leakage of offsite ac buses.

20 gpm per RCP, unless a lower value is justified.

Quality As indicated in Regulatory As indicated in Regulatory As indicated in Regulatory Assurance Position 3.5. Position 3.5. Position 3.5.

1.155-22

APPENDIX B (Continued)

Instrumentation and Control Room Indications for Verifica RCS Makeup System Isolation Condenser tion of RCS Natural Circulation (PWRs and BWRs Without RCIC) (BWRs Without RCIC) (PWRs and BWRs Without RCIC)

Technical Specifica Should be consistent with the Should be consistent with the Should be consistent with the tions for Mainte Interim Commission Policy Interim Commission Policy Interim Commission Policy nance, Surveillance, Statement on Technical Statement on Technical Statement on Technical Limiting Condition, Specifications (Federal Specifications (Federal Specifications (Federal FSAR, etc. Register Notice 52 FR 3789) Register Notice 52 FR 3789) Register Notice 52 FR 3789)

as applicable. as applicable. as applicable.

Instrumentation Must meet system functional Must meet system functional and Monitoring requirements. requirements.

Single Failure Not required. Not required. Not required.

Common Cause Design should, to the extent Design should, to the extent Design should, to the extent Failure (CCF) practicable, minimize CCF practicable, minimize CCF practicable, minimize CCF

between safety-related and between safety-related and between safety-related and non-safety-related systems. non-safety-related systems. non-safety-related systems.

• U.S.GOVERNMENT PRINTING OFFICE:1988- 20 - s80149

2 292 1.155-23

REGULATORY ANALYSIS

A separate regulatory analysis was not prepared for this available for inspection and copying for a fee at the NRC

regulatory guide. The regulatory analysis prepared for the Public Document Room, 1717 H Street NW., Washington, station blackout rule, NUREG-1109, "Regulatory/Backfit DC 20555. Copies of NUREG-1 109 may be purchased from Analysis for the Resolution of Unresolved Safety Issue the Superintendent of Documents, U.S. Government Printing A-44, Station Blackout," provides the regulatory basis for Office, Post Office Box 37082, Washington, DC 20013-7082;

this guide and examines the costs and benefits of the rule as or from the National Technical Information Service, implemented by the guide. A copy of NUREG-1 109 is Springfield, VA 22161.

FIRST CLASS MAIL

POSTAGE & FEES PAID

UNITED STATES USNRC

NUCLEAR REGULATORY COMMISSION PERMIT No. G-67 WASHINGTON, D.C. 20555 OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, $300

1.155-24