ML17202U917

Safety Evaluation Re Util Response to Station Blackout Rule 10CFR50.63.Schedule for Implementation of Proposed Hardware & Procedure Mods Required within 30 Days of Receipt of SE

ML17202U917
Person / Time
Site:	Dresden
Issue date:	12/11/1990
From:	Office of Nuclear Reactor Regulation
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ML17202U916	List: ML17202U915 ML17202U917 ML17202U919
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NUDOCS 9012210230
Download: ML17202U917 (10)

Text

I" UNITED STATES e

N LEAR REGULATORY COMMISSION ENCLOSURE 1 WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE STATION BLACKOUT RULE (10 CFR 50.63)

COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3

\\

DOCKET NOS. 50-237 AND 50-249

1.0 INTRODUCTION

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

Power" (station blackout). The station blackout (SBO) rule requires 'that each light-water-cooled nuclear power plant be ablt to withstand and recover from an SBO of specified duration, requires licensees to submit information as defined in 10 CFR Part 50.63 and requires licensees to provide a plan and schedule for conformance to the SBO rule. The SBO rule further requires that the baseline assumptions, analyses and related information be available for NRC review.

• Guidance for* conformance to the rule is provided by (1) Regulatory Guide (RG) 1.155, Station Blackout, (2) the Nuclear Management and Resources Council, Inc. (NUMARC) 87-00, Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors, and (3) NUMARC 87-00, Supplemental Questions/Answers and Major Assumptions dated December 27, 1989, which was. issued to the industry by NUMARC on January 4, 1990.

To facilitate the NRC staff's (hereafter referred to as the staff) review of licensee responses to the SBO rule, the staff endorsed two generic response formats.

One response format is for use by plants proposing to use an Alter-nate AC (AAC) power source and the other format is for use by plants proposing an AC independent response. The generic response formats provide the staff with a surranary of the results from the licensee's analysis of the plant's SBO coping capability. The licensees are expected to verify the accuracy of the results and maintain documentation that supports the stated results. Compli-ance to the SBO rule is verified by a review of the-1.icensee's submittal, an audit review of the supporting documentation as deemed necessary, and possible followup NRC inspections to ensure that the licensee ha~ implemented the appropriate hardware and/or protedure modifications that will be required to comply with the SBO rule.

The licensee for Dresden Statio~, Units 2 and 3, has proposed using an indepen-dent, dedicated non-Class lE diesel generator as an AAC power source and has submitted its original response in the applicable generic response format.

The licensee's original response was provided by letter from M. Richter (Commonwealth Edison) to T. E. Murley (NRC) dated April 17, 1989. Also, the licensee provided a response to the NUMARC 87-00, Supplemental Questions/Answers, by a letter from M. Richter to T. E. Murley dated March 30, 1990.

In addition, the licensee 9012210230 9~g6~37 PDR ADOCK 0 PDR' p

j..-

• provided a transmittal from M. Richter to P *. Gill (NRC) dated September 26, 1990, concerning the station blackout calculations for Dresden and Quad Cities Stations. Meetings were held with the licensee on October 4 and 5, 1989, December 20, 1989, and March 28, 1990, to discuss their initial and revised responses to the SBO rule. The licensee provided their final revised SBO response by letter from M. Richter to T. E. Murley dated May 18, 1990. The licensees' responses were reviewed by Science Applications International Corpora~

tion (SAIC) under contract to the NRC.

The results of the review are documented by an SAIC Techni ca 1 Evaluation Report (TER), SAIC-90/1058, "Dre~den Station Units.2 and 3, Station Blackout Evaluation," dated October 26, 1990 (Attachment 1).

2.0 EVALUATION After reviewing the 1 icensee *.s SBO submittal and t~e *SAIC TER, the staff concurs with the conclusions as identified.in the SAIC. TER (refer to Attachment 1 for details of the review).

Based on this. review, the staff findings and recommenda-tions are summarized as follows.

2.1 Station Blackout Duration The licensee _has calculated a minimum acceptable station blackout duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> based on an offsite power design characteristic group of

11Pl, 11 an Emer-

-gency AC (EAC) configuration group

110, 11 and an emergency diesel generator (EOG) reliability target of 0.95. Although the RG 1.155 requires an EOG reliability target of 0.975 for EAC group

110, 11 the staff has accepted an EDG reliability tar-get of 0.95 (see Section 2.2.2Y. The target EOG reliability was based on the unit EDGS* having an average reliability greater than 0.95 over the last 100 demands.

The Pl grouping is based on an independence of offsite power classification of.

Group 11 1 1/2, 11 a severe weather (SW) classification of Group 112 11 and *an extremely severe weather (ESW) classification of Group 111.

11 The staff review of the ltcensee's submittals indicates that Dresden Station, Units 2 and 3, does not meet one of the criteria for characterization of the independence of the offsite power to be classified as 11 I 1/2 11 group. This criteria (see RG 1.155, Table 5) states that, "After loss of the nonnal ac power *source there is an automatic transfer of a 11 safe shutdown buses to one preferred alternate power source. If this source fails, there may be one or more manual transfers of power source to the remain1ng preferred or alternate offsite power sources.w At the present time, Dresden Station has only one manual transfer of one safe shutdown bus to an alternate offsite source (i.e.,

transfer between buses 24-i and 34-1) and does not meet the above stated criteria and, therefore, would be classified as 11 I3 11 group.

In order to achieve the 11 I 1/2 11 classification, a second safe shutdown bus transfer*capa-bility is required.

The second safe shutdown bus transfer capability may be obtained (i.e., between buses 23-1 and 33-1) via the new cable circuits proposed to be installed by the licensee from the proposed AAC power source (non-Class lE diesel generator) to buses 23-1 and 33-1 (see Figure 1 of Attachment 1).

However, in order to credit this cross-connect as a safe shutdown bus transfer, the cable connections from the proposed AAC source to the safety buses in Unit 2 and Unit 3 would have to be made safety grade.

The licensee did not

• indicate in their submittal whether or not they intended to use these cross-connects for meeting the above stated criteria. *However, the staff has assumed that this arrangement would allow the safety buses in both units to be fed by either one of two independent sources of offsite power, thus, meeting the criteria for the offsite power to be classified as 11 I 1/2" group.

After reviewing the available information in the licensee's submittal, RG 1.155, NUMARC 87-00 and SAIC's TER, the staff agrees with the licensee's calculation of a 4-hour SBO coping duration.

2.2 Alternate AC (AAC) Power Source The licensee has proposed to install an independent AAC power source to operate systems necessary for the required SBO coping duration and recovery therefrom.

2.2.1 General Staff Position on AAC Power Sources The definition in 10 CFR 50.2, RG 1.155 and NUMARC 87-00 defines AAC power source in terms of four attributes: (1) connections to th~ offsite or the onsite AC power systems, (2) minimum potential for common cause failure with offsite power or the onsite emergency AC power sources, (3) timely availa-bility, and (4) required capacity and reliability. More specifically, in regard to the fourth attribute, the SBO rule reads as follows:

11 (4) *Has sufficient capacity and reliability for operation of all systems required for coping with station blackout and for the time required to bring and maintain *the plant in safe shut-down (non-design basis accident)~"

In view of the variety of types, capacities and capabilities of power sources proposed as AAC sources by various licensees, the staff has characterized pro.:..

posed AAC power sources a~ being either optimum, fully capable or partially capable. This characterization, which relates only to the capacity attribute cited above, was necessary in order to facilitate the staff review of licensee responses to the SBO rule. It does not invalidate or revoke any of the require-ments or guidance applicable to AAC power sources.

An optimum AAC power source design is one that is capable of powering, simultan-eously* both safety trains of normal safe shutdown systems and equipment.

Such a design, following actuation of the AAC source, would provide completely re-dundant normal safe shutdown capability during an SBO and recovery therefrom from the main control room.

A fully capable AAC power source design is one that is capable of powering at least one complete.safety train of normal safe shutdown systems and equipment *.

This includes. decay he.at removal, battery charging, HVAC (heating, ventilation and air conditioning), emergency lighting, and the associated controls and instrumentation. Thus, although redundant capability is not available, a fully capable AAC source would enable attainment of safe shutdown during an SBO and*

recovery therefrom from the main control room.

.. A minimally capable AAC power source design is one that is not capable of powering all (or any) normal safety train related safe shutdown equipment; but, it is capable of powering specific equipment that, in conjunction with extensive manual operator actions both inside and outside of the control room, is critical for attaining safe shutdown during an SBO.

Appendix R diesels proposed as an AAC.source are examples of minimally capable AAC sources. With this design, operability of the main control room could not be assured unless

• the batteries were sized to *operate for the SBO duration, or battery charging capability was provided by the AAC source.

2.2.1.1 Connectability of AAC Power Sources The basic criteria governing the connectability of an AAC power*source are contained in 10 CFR 50.2 (AAC source should be connectable to but normally

. riot connected to the* offs*i te or ons ite emergency AC power systems) and *10 CFR 50.63 (SBO-should not assume.a concurrent single failure or design basis acci-dent). Therefore, in a one unit site (or in multi-unit sites where an inde-pendent AAC (non-EOG) power source* is proposed for only one unit), as a mini-

. mum, an AAC source need only be connectable to one set of safe shutdown *equip-ment, regardless of whether or not that equipment is part of a safety train.

2.2.2 Proposed AAC Power Source The licensee for Dresden had.originally proposed using existing EOGs as AAC*

power sources for meeting the SBO rule. But Dresden*EDGs do not meet the minimum redund~ncy requirements in order to qualify as AAC power sources.in accordance with 10 CFR 50.2, RG 1.155 and NUMARC 87-00. Subsequently, the licensee proposed an independent non-safety related diesel generator as an AAC power source sized for SBO loads of one unit only.

However, during further discussions with the staff, the licensee proposed to install a diesel generator C>f larger capacity (sized for SBO loads for both units) provided the staff would accept a lower reliability target of existing EOGs, that is from 0.975 to 0.95. Since Dresden is a two unit site with only three EOGs (one EOG dedicated to each unit and one EOG shared between both units), it was the staff's judge-

• ment that an additional large independent diesel generator would be beneficial and provide added safety margin. *Therefore, the staff agreed with the licensee's proposal for providing a larger diesel generator for Dresden in order to select a lower reliability target than that required by RG 1.155. The.

staff's acceptance of a lower EOG reliability target than that required by the RG 1.155 is limited to EOG configurations similar to Dresden Station and is contingent upon the following:

l.

The MC power source is sized to power the complete contingent of safety related. and non-safety related. loads associated with one safety division of each unit simultaneously that are normally expected to be available for the loss of offsite power (LOOP) condition.

2.

The AAC power source is connectable to all EOG buses of all

. the units.

3.

The AAC source should be diverse from existing EDGs.

Lack of diversity must be justified by addressing how common mode failures are minimized.

By 1 etter dated May 18, I990, the 1 i censee proposed an AAC power source which will have the capacity (5,700kW, 2,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> rat.ing) for supplying all loads necessary to achieve and maintain safe shutdown for both units simultaneously for the loss of offsite power (LOOP) condition. The proposed AAC power source will be connectable to all EOG buses of both units (23-1, 24-I, 33-I and 34-1).

The proposed AAC source for Dresden Station, Units 2 and. 3, is an independent non-Class IE diesel generator which can provide power to any of the four safety buses of Un.its 2 and 3.

• The 1 i censee has stated that this power source will be available within I hour from the onset of an SBO event and has sufficient capacity.and capability to power one division of the shutdown loads of each unit siinultaneously. The licensee also stated that the AAC power source will

. meet the criteria.in Appendix B of NUMARC 87-00. Therefore, based on the licensee.'s statement, the proposed AAC power source has* sufficient cap*acity for supplying the full complement of safe shutdown loads, including heating,.

ventilating and air conditioning (HVAC), of at least one safety division; that is, the AAC source has sufficient_ capacity and capability to power the LOOP loads for one safety division.

Under this basis the proposed AAC source would be in the fully capable category cited in Section*2.2.1. _

_ As discussed in Section 2.1, the proposed circuits for connecting th* AAC source to the safe shutdown buses may be credited as the cross-tie between safety buses 23-1 and 33~1. However, all the connections from safety buses 23-1, 24-1, 33-1 and 34-1 to AAC power source output circuit breaker would have to be safety grade since all these circuits are directly connected to the AAC power source output breaker.

Recommendation:

All the connections from safety buses 23-1, 24-1, 33-1 and 34-l to, but no.t including, the AAC power source ou,tput circuit breaker should be installed safety grade (Class IE).

The licensee should provide a full descrip-tion including the nature. and objective of this modification and AAC power source evaluation to conform to Appendix B of NUMARC 87-00 and include this descr.iption in the SBO documentation that is to be maintained by the 1 icensee.

2.3 Station Blackout toping Capability The characteristics of the following plant systems and components were reviewed to assure that the systems hav*e the availability, adequacy and capability to achieve and maintain a safe shutdown and recover from an SBO for a 4-hour

• coping duration.

2.3.1 Condensate Inventory for Decay Heat Removal The licensee has stated that the isolation condenser in conjunction with the HPCI system would be used for decay heat removal during a SBO event. Since the isolation condenser system receives make-up water from the river, an inexhaust-ible supply of water inventory for decay heat removal is available. The staff, therefore, concludes that there is sufficient condensate water to cope with an SBO of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

... The diesel-driven fire pump will be used to provide isolation condenser make-up during an SBO event. However, the licensee did not address clog-free river water suction and the net positive suction head (NPSH) for the diesel-driven fire pump(s) concerning its operability to provide isolation condenser makeup in their latest submi.ttal dated May 18, 1990.

Recommendation:

The licensee should verify that the diesel-driven fire pumps(s) will have clog-free river water suction and sufficient NPSH to supply isolation conaenslr makeup.

2.3.2 Class lE Battery Capacity The licensee has determined that there is sufficient battery capacity for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> at which time the AAC power source will energize a battery charger on each unit.

The staff agrees with the licensee's assessment that the battery can support the safe shutdown loads for one hour.

2.3.3 Compressed Air The licensee has stated that no air operated valves are relied upon to cope with an SBO for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

The relief valves needed for depressurization and decay heat removal are de powered and do not depend on compressed air for operation.

Compressed air can be restored once the AAC power source becomes available after 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

After reviewing the licensee's submittal and SAIC's TER, the staff agrees with the SAIC assessment that no air operated valves are relied upon during the first

• hour of an SBO event.

2.3.4 Effects of Loss of Ventilation*

The licensee has stated that the AAC power source will supply power to the HVAC system within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. During the first hour, no HVAC will be available to areas containing SBO equipment.

The licensee's analyses show that reasonable assura~ce of operability is established for the containment and all dominant areas of concern during the first hour.

Procedure revisions are required for openi~g access and panel aoors in the control room, and the auxiliary electrical equipment rooms (AEERs).

The licensee claims that all equipment located in the HPCI room and the isolation condenser area is operable at the calculated 1-hour temperature except for the level indication in the isolation condenser area. The licensee has proposed to install an isolation condenser level indication trans-mitter qualified for the expected SBO thermal profile.

We find this to be acceptable~ The licensee'~ evaluation of the HPCI room indicates a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> temper-ature value of.130°F.and a final temperature of 195°F. The extrapolation tech-nique employed by the licensee for the first hour based on NUMARC 87-00 methodo-logy for the final steady state temperature* during the required duration is not appr*opriate since the NUMARC m~thodology develops an average steady state bulk air temperature and is not time-dependent (See Attachment 1 for details).

Since the HPCI only needs to operate for a short period of time to make up the primary system, the 1-hour temperature and the steady state temperature would

• ' be expected to be approximately the same.

In addition, it appears from the information provided in the licensee's submittals that all SBO equipment may not have been evaluated for the effects of loss of ventilat;on.

Also, the licensee's submittal does not provide information whether the control room and AEERs heat-up calculations were made using initial temperatures corre-sponding to the maximum bounding design temperatures of these rooms~ including maximum technical specificat;on temperatures.

Recommendations:

(1) The 1 icensee should address the discrepancy between the I-hour temperature and the steady state temperature calculated for the HPCI room, (2) the licensee should address SBO equipment that may not have been evaluated for the effects of loss of ventilation, and (3) the licensee should verify whether the control room and AEERs heat-up calculations_ were performed using the pertinent initial maximum bounding design temperatures for these rooms in. 1 ieu of norma 1 room temperatures. These evaluations and verifications and any resulting modifications should be included in the documentation supporting the SBO submittals that are to be maintained by the licensee.

2.3.5 Containment Isolation The licensee has stated that the stations' list of containment isolation valves (CIVs).was reviewed to ensure that containment integrity can be provided during SBO conditions.

In addition to the valves meeting the exclusion criteria listed in NUMARC 87-00, Section 7.* 2.5, the licensee excluded the valves that are always procedurally closed during power operation or valves that are upstream or down-stream of CIVs.

The licensee further states that the valves that may require manual actuation to ensure containment integrity under SBO conditions will be.

incorporated into the appropriate station procedure.

The licensee's criteria for excluding CIVs that are always procedurally closed dur.ing full power operation is not in accordance with NUMARC 87-00, Section 7.2.5. The licensee did not state whether these valves ar.e normally locked c.losed during power. operation or if they wi 11 fail closed on loss of ac power or air. In addition, the licensee did not provide information on valve position indication (e.g., local mechanical, de powered, or AAC) for these valves and manual operated valves. Also, the licensee needs to revise Table 5-1 to include all CIVs listed in Sub-Section 10.2 including M02(3)-1001 A/B (see review package dated September 26, 1989).

Recommendation:

The licensee should indicate whether the CIVs that are pro-cedurally closed during power operation are normally locked closed or they will fail closed on loss of ac power or air. In addition, the licensee should ensure that these air or ac operated CIVs remain properly positioned during an SBO event by providing capability for valve position indication, independent of preferred and Class lE power supplies. This information and verification including clarifi-cations for the CIVs listing discrepancies should be included in the documenta-tion supporting the SBO submittals that are to be maintained by the licensee.

• . 2.3.6 Reactor Coolant Inventory The licensee has performed an analysis. and has stated that less than 20,000 gallons of water are required for reactor make-up water for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The con-densate storage tank maintains a minimum volume of 90,000 gallons in reserve for the HPCI system which exceeds the.required quantity for coping with a 4-hour SBO event.

After reviewing the licensee's submittals and SAIC's TER, the staff agrees with the SAIC assessment that adequate RCS inventory will be maintained and finds it acceptable (refer to Attachment 1 for details).

2.4 Procedures and Training The licensee has stated that procedure rev1s1ons not associated with modifica-tions will be completed one year after the issuance of this SER.

Procedure revi-sions associated with the AAC power source_ will be completed by *December 1995.

The proposed procedure modifications indicated above were not reviewed, but the staff expects the licensee to maintain and implement these procedures including any others (fire protection initiation) that may be required as part of the revised r~sponse to ensure an appropriate response to an SBO event. Although personnel training requirements for an SBO response were not specifically addressed by the licensee's.submittal, the staff ~xpects the licensee to implement the appropriate training to ensure an effective response to the SBO.

Iri addition, *adequate emergency liyhting should be provided to carry out the needed operator actions during an SBO.

2.5 Proposed Modifications The installation of an independent non-Class lE*AAC diesel *generator comprises a major hardware modification (see Section 2.2.2). The AAC power source will be connected to all 4kV safety buses. The new cable circuits to be installed from the proposed AAC source to the safety buses may be credited as a cross-tie between safety buses 23-1 and 33-1 in order to classify the independence of the offs.ite power as* "I 1/2" group.

However, these connectiOns from the AAG source breaker to the safety buses (23-1, 24-1, 33-1 and 34-1) would have to be Class lE

~ircuits for taking credit for the cross-tie between buses 23-1 and 33-1.

In add1tjon, the liceniee has proposed changts in logic circuits for the shared EOG (EOG 2/3) to a.llow. ;t to be connectable to the safety buses 23-1 and 33-1 simultaneously~ The staff has not evaluated this modification since it does not have any bearing on the SBO issue. However, the licensee may submit this modification under separate review if desired *..

Also, the licensee has proposed the new isolation condenser level indication transmitter, qualified for the expected SBO thermal profile, to be installed.

to ensure that control room iridication is provided during an SBO event.

Recommendation:

The licensee should include a full description including the nature and objectives of the required modifications* identified abov~ iti the documentation supporting the SBO submittals that is to be maintained by the licensee.

-e 2.6 Quality-Assurance (QA) and-Technical-Specifications (TS)

The licensee has stated that all SBO equipment is either currently covered by the QA program or will be covered by a QA program in accordance with the guidance of RG 1.155. The staff finds the proposed licensee actions in this area to be acceptable *

. The Technical Specifications (TS) for the SBO equipment are currently being con-sidered generically by the NRC in the context of the Technical Specification

.Improvement Program and remains an open item at this time. However, the staff expects plant procedures to refl~ct the appropriate testing and surveillance

• requirements to ensure the operability of the necessary SBO equipment. If,the staff later determines that TS regarding the SBO equipment is warranted, the licensee will be notified of the implementation requirements.

2.7 EOG Reliability Program The licensee submittal on SBO did not specifically address a convnitment to implement an EOG reliability program to ~onform to the guidance of RG 1.155, Position 1.2. However, in the submittal of March 30, 1990, the licensee has committed to establish a reliability program in accordance with the final resolution of GI B-56. Although, the licensee has committed to a reliability program pending resolution of GI B-56, it is required to implement a program that meets the guidance of RG 1.155, Position 1.2, Items 2 through 5.

Recommendation:

The licensee shouid provide confirmation and include it in the do~umentation supporting the SBO submittals'that are to be maintained by-the licensee, th~t such a program meeting the guidance of RG 1.155, Position 1.2, Items 2 through 5, is in place or will be implemented.

2.8 Scope of Staff Review The station blackout rule (10 CFR 50.63) requires licensees to submit a response containing specifically defined information. It also requires utilities "to have baseline assumptions, analyses and related information used in their coping_

evaluation available to NRC." 1he staff and its contractor (SAIC) did not perform.

a detailed review of the proposed procedure modifications which are scheduled for l~ter implemeritation after the modifications that could result from the staff recollillendations in this SER.

However, based on our review of the licensee sup~

porting documentation, we have identifi~d the following areas for focus in any followup inspection or assessment that may be undertaken by the NRC to further

.*verify conformance with the SBO rule.

a.

Hardware and procedural modifications,

b.

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

c.

operator staffing and training to follow the identified actions in the. SBO procedures,

.. d.

EOG reliability program meets, as a minillllm, the guidelines of RG 1.155, Position 1.2, Items 2 through 5,

e.

equipment and components required to cope with an SBO are incorporated in a QA program that meet the guidance of RG 1.155, Appendix A, and

f.

actions taken.pertaining to the specific reconunendations noted above in this SER.

3.0

SUMMARY

AND CONCLUSIONS The ~aff has reviewed the licensee's response to the SBO rule (10 CFR 50.63) and the Technical Evaluation Report prepared by the staff's consultant, SAIC *.

Based on our review, additional analyses and confirmations described in the re~

commendations provided in this SER need to be completed. These include confir-mation of the installation of Class lE circuits from the AAC source output circuit breaker _to the safety buses of both units, verification of adequate diesel driven fire pump NPSH and clog-free river water suction for its opera-bility, verification of control room and AEERs heat-up calculations using maximum bounding initial design temperature, resolution of the discrepancy between the 1-hour and steady state temperature for the HPCI room, justification for ex-cluding CIVs that are procedurally closed and clarification for the CIVs listing discrepancies.

The licensee should ma~ntain these analyses and confirmation in the documentation supporting the SBO submittal available for further inspection and assessment as may be undertaken by the NRC to audit conformance with the SBO Rule.

Based on our review of the submittal, we find th~ licensee's design and p~o posed method of dealing with an SBO to be in conformance with the SBO rule.

However, the schedule for implementation of the proposed hardware and associated procedure modifications, including those resulting from the recommendations documented in this Safety Evaluation. (SE), should be provided to the NRC staff within.30 days of receipt of this SE, in accordance with

• 10 CFR 50.63(c)(4).

Principal Contributor:

N. K. Trehan Dated:

December 11, 1990