NRC-95-4446, Requests That NRC Meetings Discuss Advanced PWR Fire Protection & Electrical Design Regulator Issues

Requests That NRC Meetings Discuss Advanced PWR Fire Protection & Electrical Design Regulator Issues

ML20083B973
Person / Time
Site:	05200003
Issue date:	05/01/1995
From:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:	Quay T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
DPA-INT00934446, DPA-INT934446, NTD-NRC-95-4446, NUDOCS 9505150035
Download: ML20083B973 (15)

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W65tiflgliouse Eriargy Systems Box 355 Pinsburgh Pennsylvania 15230-0355 Electric Corporation NTD-NRC-95-4446 DPA/ INT 0093 May 1,1995 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 ATTENTION: T. R. QUAY SUlHECT: WESTING 110USE REQUEST FOR NRC MEETINGS TO DNCUSS ADVANCE 3 PWR FIRE PROTECTION AND ELECTRICAL DESIGN REGULAKRY ISSUES

Dear Mr. Quay:

Westinghouse is working with Kansai Electric to develop an ed PWR design for Japan. The plant design is intended to have international licensability. ,1y, Westinghouse met with NRC to discuss the potential for a shared control room design for t.. same program. The meeting included a Westinghouse presentation of the proposed design and NRC identification of potentiallicensing issues that would need to be addressed.

Westinghouse is hereby requesting additional meetings of the same type on fire protection and electrical design issues. The meetings would be one-half day each and would be used as a forum to identify potential regulatory issues related to proposed APWR design and to gain in-sights into the regulatory requirements that exist in these areas.

Attached are summaries of the areas that would be discussed. Please provide the attachments to the appropriate technical branch review areas.

Please contact Andrea L. Sterdis on (412) 374-5292 to schedule the electrical design meeting and Cindy L. llaag on (412) 374-4277 to schedule the fire protection meeting. If you have any questions concerning this transmittal contact either Andrea or Cindy or lirian A. McIntyre at (412) 374-4334.

W' !g/ p N. J. Liparuto, Man ger Nuclear Safety Regulatory and Licensing Activities

/nja Attachment 9505150035 950501 PDR ADOCK 05200003

.m A PDR I l

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4 h NRC / Westinghouse Meeting on the Advanced PWR Electrical Distribution System Design -- Regulatory Requirements Related to Addressing Station Blackout i r

Meeting Purpose  ;

The purpose of the meeting is to gain additional in-sights into the regulatory requirements developed to address station blackout for advanced evolutionary plant designs (with active safety systems).

These in-sights will be used to support development of design criteria and determination of the final I

electrical distribution system configuration for a specific advanced plant design program for an international utility customer. This new design includes additional features that may affect the ,

application of the current regulatory approach for evolutionary plants discussed in the SECY 93-087.

The proposed design includes a focr-train electrical distribution system that incorporates features to allow performance of limited on-line maintenance for selected systems and considers feasible design alternatives for incorporating four emergency diesel generators and the associated safety-related emergency busses.

Specific Meeting Goals

1. Discuss any appropriate background, philosophy, and current thinking related to the regulatory requirements for station blackout, including future direction that may not be indicated in the current regulatory guidelines and requirements.

2. Answer some specific questions related to the approach for resolution of the station blackout certification issue for an advanced plant design.

3. Provide any other specific recommendations to support the development of both high-level system design criteria and specific system design implementation details for the electrical distribution system and other associated systems and equipment for the advanced plants that may be impacted by regulatory requirements to address this issue.

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c NRC / Westinghouse Meeting on the Advanced PWR Proposed Agenda

. Introduction / Program Overview Design Review Program -- Task Summary

1. Resolve important safety improvement issues (such as certification issues for steam generator tube rupture mitigation ATWS, and so forth) to support specific system  ;

design activities.

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2. Review the safety-related system design for an advanced Japanese PWR design (a four-loop active, evolutionary plant) against the current U.S. NRC regulatory requirements and EPRI URD requirements.

. Brief Overview of the Electrical Distribution System Design Review Regulatory Review EPRI URD Review t

. Addressing Station Blackout Design Issues  !

Blackout Regulatory Requirements  ;

10 CFR 50.63 SECY 93-087 ALWR Certification Issues (Item I.D -- Station Blackout) l Regulatory Guide 1.155 Potential Design Approaches Specific Design Questions (see attached questions)

• Conclusion l

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1 General Comments on the Proposed Meeting

1. The meeting purpose and format is expected to be similar to a previous NRC meeting held in Febmary 1994 to discuss the concept of shared main control rooms for the same advanced plant design program. At the previous meeting, Westinghouse and the NRC discussed the background and philosophy related to the regulatory requirements for a shared main control room design.

2. As with the previous shared main control room meeting, Westinghouse would like to talk with the appropriate NRC reviewers to discuss the station blackout issue. The meeting will use a presentation format, led by Westinghouse, to facilitate an infonnal working discussion of the following:

a) Key design features that may benefit plant response to station blackout b) The electrical system design approach to address station blackout c) Discussions on each of the identified questions

3. Westinghouse wants to better understand the background, philosophical approach, and any cunent thinking related to the regulatory requirements for station blackout. This understanding will help to establish the appropriate design criteria and approach since the proposed design includes an equipment configuration that was not considered in the development of the current NRC regulatory requirements for station blackout.

In addition, it would be helpful to identify any other emerging issues or industry trends that are NOT reflected in current regulatory information, but that should be considered in the development of electrical distribution system design criteria. 1

4. The intent of the meeting is NOT to have the NRC staff lead the meeting or provide written responses to these questions at or prior to the meeting. Instead, the meeting will serve as an informal fomm for the reviewers to discuss their concerns, philosophy, and other considerations in evaluating the capability of an advanced plant design to adequately address station blackout issues.

It is hoped that the staff participants will briefly review the questions and that based on their current knowledge of this issue, they should be able to discuss the appropriate considerations for these issues and questions. It is NOT expected to take a significant amount of staff time to prepare for the meeting and no additional NRC actions are currently anticipated following the meeting.

The discussion will help Westinghouse provide inputs in the development of the design criteria for the plant. Also, Westinghouse will provide the NRC with a copy of the meeting summary prepared for the utility customer.

5. The meeting objective is NOT to focus on detailed electrical system design features or to focus on the on-line maintenance issue.

6. We expect the meeting to last about a half day. However, we would like to start the meeting first thing in the morning to allow time for extended discussion, just in case it is needed.

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Specific Station Blackout Design Questions

1. What is the reason for requiring an alternate ac source as a countermeasure for station blackout for evolutionary plants [SECY 93-087] rather than allowing a coping study option, which is allowable for currently operating plants?

a. For an advanced plant design with a four-train system and with grid and diesel-generator reliability that is significantly better than U.S. experience (see attached U.S. /

Japanese electrical reliability comparison data), if a coping study in accordance with the guidelines in Regulatory Guide 1.155 is satisfactorily completed, can the requirements in SECY 93-087 for an alternate ac power source (AAC) be waived?

It is recognized that this improved electrical system reliability is not applicable to U.S. utilities.

A coping study approach would be used to identify required system modifications to cope with the specified blackout period.

The coping study would be based on a blackout duration of four hours and would follow the guidelines in 10 CFR 50.63 and Regulatory Guide 1.155.

b. Is it understood by the NRC that the blackout duration before the recovery of site power required by the Japanese licensing authority (MITI)is presently 30 minutes?

2. What constitutes diversity in on-site standby power supplies?

a. Can a diverse diesel-generator design be used in place of an AAC power source? If an evolutionary plant design includes four 50-percent capacity, Class IE emergency diesel generators, using two different (diverse) equipment designs (see Figure 1),

would the NRC still require incorporation of an AAC power source?

b. If diverse diesel-generator designs are acceptable, what kind of diversity is required for support systems such as starting / field-flashing / fuel / cooling systems?

c. Is there sufficient design diversity if the same diesel-generator unit is used, but each unit has multiple starting / field-flashing / fuel / cooling systems and possibly a redundant electrical distribution path and breaker to the associated distribution bus?

3. Is maintaining hot sht.tdown during the station blackout period sufficient?

The definition for " safe shutdown (non-design basis accident (non-DBA)) for station blackout" in 10 CFR 50.2 indicates that shutdown conditions in Hot Standby or Hot Shutdown are acceptable.

This means that it is not required to bring the plant to cold shutdown or to size the blackout ac power source to accommodate equipment required to establish and maintain cold shutdown conditions following a station blackout.

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Specific Station Blackout Design Questions (continued) l i

4. What is definition of "one complete set of normal safe-shutdown loads?" as specified in i SECY 93-087 and 10 CFR 50.27

- - This is needed to develop specific design criteria to identify the appropriate systems and equipment. <

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5. Can an AAC power source be shared between two units? If this is possible, what is the basis ,

for determining the required capacity? Must it be sized large enough to handle both units simultaneously?

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- For advanced plant designs, it is NOT intended to share safety-related emergency ac sources between units at multiple unit sites for any design basis events. However, if the diverse diesel-generators are credited for station blackout mitigation, then there may be a benefit to have a capability to power " normal safe shutdown loads" from the emergency diesel-generators of another unit during a station blackout event.

10 CFR 50.63 indicates that sharing AAC sources between multiple units is acceptable and that where onsite emergency ac sources are NOT shared between units [for design i basis events], the AAC "must have, as a minimum, the capacity and capability for i coping with a station blackout in any of the units." -

- 10 CFR 50.63 indicates that the AAC must be sized for simultaneous shutdown of all ,

multiple units only for older plant designs where safety related emergency power  !

'. sources are shared between umts. .;

6. Attached are four alternative electrical distribution designs (using a 4-train arrangements with 50% capacity diesel-generators) currently being considered. These will be briefly discussed during the third agenda item related to

• Potential Design Approaches."

Design Alternative Alternate AC Source Response during Blackout l

a. 4 identical DGs None Share from neighboring unit

b. 4 identical DGs Diverse DG* Use dedicated AAC

c. 2 sets of 2 diverse DGs None Use operable DG

d. 4 identical DGs (with None Use operable DG I diverse support)

• The diverse ac power source or safety-related emergency DGs used in place of an AAC would be sized as required for station blackout requirements.  ;

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7. What are the requirements for testing reactor coolant pump seals under station blackout j conditions?

a. Is there any information available on the content of draft rule on this issue that is currently being prepared?

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Supplemental Questions -- Seal Injection

1. Is it possible to credit powering a charging pump for seal injection and not adding dedicated seal injection pump?

It is expected that in this case, any required support systems would have to be powered also.

2. Is a de-powered seat injection pump acceptable, provided that the batteries are properly sized for the appropriate coping period?

3. What classification is required for the reactor coolant pump seal injection piping?

Currently, at least the containment isolation portion and the reactor coolant pressure boundaries portions must be safety-related.

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Advanced PWR Design -- Background Information l

l Design Overview -- Current Approach to Address Station Blackout -

- Four-division electrical distribution system

- Diverse emergency diesel-generators The diesel-generators are sized to handle CVCS charging pumps plus required support loads

- No alternate ac power source and no dedicated seal injection pump l Turbine-driven AFW pumps

- DC power for instrumentation and control and for safety-related MOVa

- DC power for other investment protection capabilities (main turbine coast-down tube oil, etc.)

Systems Proposed for On-Line Maintenance Integrated Safeguards System Emergency Boration System / Chemical and Volume Control System

- Auxiliary Feedwater System Component Cooling Water System Sea Water System

- Instrument Air System Safeguards Components Areas IIVAC Emergency Diesel Generators AC Power Systems (including battery chargers)

Systems NOT Proposed for On-Line Mainte.. mee DC Power System 120 VAC Instrumentation Power Instmmentation and Control Systems Reactor Protection System Plant Control System Containment Isolation Valves (multiple systems)

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i Comparison of Reliability Data for the Electrical Grid and the Safety Related Emergency Diesel Generators

. Loss of Offsite Power Initiating Event Frequency  :

With full load Without full load rejection capability . - rejection capability U.S.* 8.2E-2 / year 1.2E-1/ year Japan ** 4.9E-3 / year -

6 % of U.S. value - --

Improvement 94 % -

over U.S. data

- Diesel-Generator Reliability (Component Failure Data)

Fails to start Fails to run U.S.* 1.4E-2 2.4E-3 Japan ** 1.l E-3 1.7E-4  ;

8 % of U.S. value 7 % of U.S value Improvement 92 % 93 %

over U.S. data

• EPRI ALWR URD, Volume 2 (Evolutionary Plant), Chapter I A -- Key [PRA]

Assumptions and Groundrules (KAG) Document

• • Provided by Mitsubishi Heavy Industries l

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NRC / Westinghouse Meeting on the Advanced PWR Fire Protection Design Criteria Meeting Purpose The purpose of the meeting is to gain additional in-sights into the regulatory requirements developed to address fire protection design for advanced evolutionary plant designs (with active safety systems).

These in-sights will be used to support development of design criteria and determination of the final fire protection layout for a specific advanced plant design program for an international utility customer. This new design includes additional features that may affect the application of the current regulatory approach for evolutionary plants discussed in the SECY 93-087.

The proposed plant design includes a four-train electrical distribution system that incorporates features to allow performance of limited on-line maintenance for selected systems and considers feasible design alternatives for incorporating four emergency diesel generators and the associated safety-related emergency busses.

Specific Meeting Goals

1. Discuss the proposed approach for the key program design issues and the approach for the high-level fire protection design criteria.

2. Answer some specific questions related to thc approach for resolution of the station blackout cer1ification issue for an advanced plant design.

3. Discuss any appropriate background, philosophy, and current thinking related to the regulatory requirements for fire protection design, including future direction that may not be indicated in the current regulatory guidelines and requirements.

4. Provide any other specific recommendations to support the development of high-level fire protection design criteria.

5. Discuss the safe shutdown approach e:.d requirements for design basis events, including fire and main control room evacuation, and for station blackout (which is a non-design basis event).

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. i NRC / Westinghouse Meeting on the Advanced PWR '

Proposed Agenda .

• Introduction / Program Overview Specific Task Identify and discuss key issues related to the fire protection design that could potentially impact plant layout, overall system design, and fire protection system design.

Task Activities Review the fire protection design criteria for a 4-loop active, evolutionary plant design being built in Japan against the current U.S.

NRC regulatory requirements and against the EPRI URD requirements.

• Brief Oversiew of Current APWR Fire Protection Design Regulatory Guidelines /

Requirements j Applicable NRC guidelines / requirements used for the APWR design review 10 CFR 50.48, Appendix R NUREG-0800 (Standard Review Plan), Section 9.5.1 (BTP CMEB 9.5-1)

SECY 93-087 ALWR Certification Issues I.E Fire Protection i

• Clarification of Key Program Design Issues .

Assumptions for coincident single failures Extent of the fire (exposure fire)

Loss of offsite power Coincident events Credit for fire damage repair .

Credit for unaffected, nonsafety-related equipment Safe (cold) shutdown capability  :

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Approach for Development of Ifigh Level Fire Protection Design Criteria Separation Outside Reactor Containment

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Between safety-related divisions '

a Between safety-related and nonsafety-related areas t

. Within safety-related divisions  !

Separation Inside Reactor Containment  !

Shutdown Capability (hot versus cold) i Protection During Various Plant Operational Modes Integration with other NRC safe shutdown design requirements  ;

• Conclusion  !

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l General Comments on the Proposed Meeting

1. The meeting purpose and format is expected to be similar to a previous NRC meeting held in February 1994 to discuss the concept of sha ed main control rooms for the same advanced plant design program. At the previous meeting, Westinghouse and the NRC discussed the background and philosophy related to the regulatory requirements for a shared main control room design.

2. As with the previous shared main control room meeting, Westinghouse would like to talk with the appropriate NRC reviewers to discuss the overall fire protection design approach for advanced plants, focusing on several key design issues that must be addressed to support development of high-level fire protection design criteria.

The meeting will use a pres:ntation format, led by Westinghouse, to facilitate an informal working discussion described in the proposed agenda.

.,. Westinghouse wants to better understand the background, philosophical approach, and any current thinking related to the regulatory requirements for fire protection design. This understanding will help to establish the appropriate high-level fire protection design criteria and approach.

In addition, it would be Selplul to identify any other emerging issues or industry trends that are NOT reflected in current regulatory information, but that should be considered in the development of fire protection design criteria. For example, is there consideraticn for incorporation of NFPA-804 guidance for advanced plant designs.

4. The intent of the meeting is NOT to have the NRC staff lead the meeting or provide written information on the key issues at or prior to the meeting. Instead, the meeting will serve as an informal forum for the reviewers to discuss their concerns, philosophy, and other considerations in evaluating the fire protection capabilities for an advanced plant design.

It is hoped that the staff participants will briefly review this information and questions, and based on their current knowledge of this issue, they should be able to discuss the appropriate considerations for these issues and questions. It is NOT expected to take a significant amount of staff time to prepare for the meeting and no additional NRC actions are currently anticipated following the meeting.

The discussion will help Westinghouse provide inputs in the development of the design criteria for the plant. Also, Westinghouse will provide the NRC with a copy of the meeting summary prepared for the utility customer.

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i General Comments on the Proposed Meeting (continued) ,

5. ' The meeting objective is NOT to focus on specific fire protection system design requirements such as:

. Detailed fire protection system features and assumptions

- . Automatic fire detection

. -. _ Automatic suppression (water, CO ,2 halon, etc.) .

Cable routing  ;

- Electrical dis:ribution separation 1

- Main control room fire protection Fire equipment performance following seismic events

6. We expect the meeting to last about a half day. However, we would like to start the meeting '.t first thing.in the morning to allow time for extended discussion, just in case it is needed.  ;

7. The APWR Program reviewers are following the advanced plant fire protection design -

activities for the Westinghouse AP600 Program, so they are aware of the appropriate NRC approach and comments for that program.

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e if Specific Fire Protection Design Questions i

1. What special fire design considerations should be included for a plant design with a four-train configuration? -

2. Do the requirements of NFPA 804 supersede the requirements of NFPA 803 and are these new  !

requirements incorporated into the regulatory fire protection design requirements, or will they be in the near future?  !

3. Can credit be taken for nonsafety-related equipment that is unaffected by a fire for establishing ,

and maintaining safe shutdown (for example, use of the startup feedwater, steam dumps, and condenser to provide cooldown instead of only crediting only safety-related systems such as auxiliary feedwater and steam generator atmospheric steam dumps)?

4. What are the key / imponant fire protection design requirement ' differences to be considered with the use of a remote shutdown workstation for a plant design with a digital control and protection system, which is significantly different from the more limited operational capabilities of the remote shutdown panel for conventional designs in current plants?

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L Advanced PWR Design -- Background Information Design Overview

-- Four-division arrangement for systems with on-line maintenance Four emergency diesel-generators (potentially arranged as two diverse pairs) ,

Turbine-driven AFW pumps

- DC power for instrumentation and control and for safety-related MOVs

. Systems Proposed for On-Line Maintenance

- - Integrated Safeguards System .

-- Emergency Boration System / Chemical and Volume Control System Auxiliary Feedwater System

- Component Cooling Water System Sea Water System -

Instrument Air System -

Safeguards Components Areas HVAC Ernergency Diesel Generators AC Power Systems (including battery chargers)

Systems NOT Proposed for On-Line Maintenance ~!

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-- DC Power System 120 VAC Instrumentation Power -!

Instmmentation and Control Systems  ;

Reactor Protection System Plant Control System '

Containment Isolation Valves (multiple systems)

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