ML18096A437

Safety Evalution Re Station Blackout Rule.Facility Deficient in Noted Areas

ML18096A437
Person / Time
Site:	Salem
Issue date:	01/13/1992
From:	Office of Nuclear Reactor Regulation
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Shared Package
ML18096A389	List: ML18096A388 ML18096A436 ML18096A437
References
RTR-REGGD-01.155, RTR-REGGD-1.155 NUDOCS 9201210068
Download: ML18096A437 (11)

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I UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION STATION BLACKOUT RULE PUBLIC SERVICE ELECTRIC AND GAS COMPANY SALEM NUCLEAR GEi.~"ERATING S'I!.A'HON, UNITS 1 AND 2 DOC'lU!.~ NOS. 50-272 ANV 50-311

1.0 INTRODUCTION

ENCLOSURE On July 21, 1988, the Code of Federal Regulations 10 CFR 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 able to withstand and recover from an SBO of specified duration, requires licensees to submit information as defined in 10 CFR 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, (issued to the industry by NUMARC on January 4, 1990.)

To facilitate the NRC staff's (hereafter referred to as 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 Alternate AC (AAC) power source and the other format is for use by plants proposing' an AC independent response. The generic response fonnats provide the staff with a su11111ary of the results from the licensee's analysis of the 9201210068 920113 PDR ADOCK 05000272 1

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• plant's SBO coping capability. The licensees are expected to verify the accuracy of the results and maintain documentation that supports the stated results. Compliance to the SBO rule is verified by a review of the licensee's submittal, an audit review of th~ supporting documentation as deemed necessary, and possible follow-up NRC inspections to ensure that the licensee has imple-mented the appropriate hardware and/or procedure modifications that will be required to comply with the SBO rule.

The licensee provided responses to the SBO Rule regarding the Salem Generating Station, by letters from S. LaBruna, and T. M. Crirrunins, Jr., of Public Service Electric and Gas Company to the U.S. Nuclear Regulatory Co11111ission dated April 17, 1989, April 30, 1990, July 30, 1990, March 1, 1991, March 28, 1991, and September 17, 1991.

The licensee's responses were reviewed by the NRC staff and by Science Applications International Corporation (SAIC) under contract to the NRC.

The results of the review are documented in the attached Safety Evaluation (SE) and the SAIC Technical Evaluation Report (TER), SAIC-91/1256, "Salem Generating Station, Units 1 and 2, Station Blackout Evaluation, dated December 13, 1991 (Attachment No. 1).

2.0 EVALUATION After reviewing the licensee's SBO submittals and the SAIC TER, the staff concurs with the conclusions as identified in the SAIC TER (refer to Attachment No. 1 for details of the review).

Based on this review, the staff finding and recorrunendations are summarized as follows:

2.1 Station Blackout Duration The licensee has calculated a minimum acceptable station blackout (SBO) duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> based on a plant offsite power design characteristic Group "Pl, 11 an emergency AC _(EAC) power configuration Group

11D, 11 _and a target emergency diesel generator (EDG) reliability of 0.975. The target EDG reliability is based on Salem Generating Station having an average EDG l

• reliability greater than 0.95 over the last 100 demands.

The 11Pl 11 grouping is based on an independence of offsite power classification Group 11 ! 1/2," a severe weather (SW) classification Group "2," and an extremely severe weather (ESW) classification Group 112."

According to Table 3.2 of NUMARC 87-00, the expected frequency of LOOPs due to ESW conditions is ESW Group

114, 11 which places the site in an offsite power design characteristic Group 11P2.

11 In the submittal, the licensee states that if site-specific data is used, the ESW group is

112, 11 which places the site in an offsite power design characteristic Group "Pl.

11 Since the licensee has failed to justify the discrepancy between their ESW grouping and the one provided in NUMARC 87-00, we consider the site to be classified as "P2.

11 We agree with the licensee's EAC classification as Group "D" based on each unit having three EDGs, two of which are necessary to safely shutdown a unit.

The licensee selected an EOG target reliability of 0.975 based on EOG reliability data for the last 100 demands.

The licensee should have an analysis showing the EOG reliability statistics for the last 20 and 50 demands in its SBO submitted supporting documentation.

Based on the plant's offsite power design characteristic Group "P2," and a target EOG reliability of 0.975 the minimum coping duration is 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

Therefore, this Safety Evaluation (SE) is based upon the plant coping capability for a duration of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

2.2.1 Condensate Inventory for Decay Heat Removal The licensee stated that 168,867 gallons of water are required to cope with a 4-hour SBO event. The plant Technical Specifications (TS) require a minimum permissible condensate of 192,069 gallons to be maintained in the condensate storage tank. This TS required capacity exceeds the amount of water necessary for coping with a 4-hour SBO event.

• Based on its review, the staff determined that the minimum coping duration for an SBO event at the Salem plant is 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (See Section 2.1). During the course of its review, the staff's consultant performed an independent analysis which indicates that approximately 214,677 gallons of water would be required for an 8-hour SBO event. Therefore, the staff concludes that there is insufficient water at the Salem plant to cope with an 8-hour SBO event.

Recommendation:

The licensee should provide an alternate and/or additional source of water to cope with an 8-hour SBO event at the Salem plant.

2.2.2 Class lE Battery Capacity The licensee performed a battery capacity calculation and verified that the 28V Class lE batteries have sufficient capacity to meet SBO loads for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

The licensee also stated that the 125V Class lE batteries have sufficient capacity to carry the loads for a 4-hour coping period provided that one non-essential load (Remote Shutdown Panel) is stripped from batteries lC and 2C within 30 minutes after the onset of an SBO event.

Based on a review of the licensee's battery capacity calculations for SBO loads, we conclude that the licensee's assumed temperature correction factor 1.08 {based on an electrolyte temperature of 65 degrees F), a design margin of 1.1, and an aging factor of 1.25 are conservative and consistent with the IEEE-485 guidance.

The licensee's battery calculations support an SBO coping duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

Information submitted by the licensee to support the ba~tery calculations for the 4-hour coping duration was used by the staff to determine whether the battery capacity was adequate for an 8-hour coping duration. The calculations for the 8-hour coping duration were performed in accordance with IEEE standard 485 using the temperature, design margin, and aging correction factors mentioned above. The results indicate that none of the A, B, and C channel 125 VDC batteries or the lA and 2A channel 28 VDC batteries have sufficient

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• capacity to last for the 8-hour coping duration.

We conclude that the Class lE battery capability is not adequate to support the SBO loads for an 8-hour SBO coping duration.

Reconunendation:

The licensee should add an alternative ac (AAC) source to power a battery charger or reevaluate and confirm the battery capability to support the SBO loads for an 8-hour SBO coping duration. If load shedding or modifications are required, the licensee should submit this information for staff review.

2.2.3 Compressed Air The licensee stated that the compressed air system will be modified by the addition of a permanently installed diesel-driven air compressor.

Upon the completion of the modification, the air-operated valves relied upon to cope with an SBO event at the Salem plant will have sufficient back-up sources independent of the preferred and Class lE power supply.

Based on its review, the staff agrees with the licensee that by adding a permanently installed diesel-driven air compressor to the compressed air system, there will be sufficient compressed air to cope with an SBO event at the Salem plant.

Reco11111endation:

The licensee should provide the plan for the implementation of the above cited modification.

2.2.4 Effects of Loss of Ventilation The licensee, using the guidance described in NUMARC 87-00, has performed plant specific analyses to determine the effects of loss of ventilation during a 4-hour SBO event and identified the dominant areas of concern (DACs) at the Salem plant (See SAIC TER for the list of the DACs and their associated calculated temperatures). The licensee stated that reasonable assurance of the operability of SBO response equipment in these DACs has been assessed in

• accordance with the guidance described in NUMARC 87-00 and concluded that plant procedure changes are required to incorporate the following operator actions which will be needed within 30 minutes of an SBO event to ensure acceptable room temperatures:

1. Open main control room SBO equipment cabinet door panels.

2. Open two doors to the corridor from the SBO unit control room.

3. Open two doors to the corridor from the NBO unit control room.

4. Open door to corridor from the watch engineer's office.

5. Open return damper from watch engineer's office to NBO unit emergency air condition systems.

6. De-energize computer inverter lA in the data logging room.

7. Open door between electric driven and turbine driven AFW pump cubicles.

Based on its review, the staff finds that the effects of loss of ventilation during a 4-hour SBO event at the Salem plant have been properly evaluated and that reasonable assurance of the operability of SBO response equipment in the DACs has been provided for a 4-hour SBO event.

Reco1T111endations:

Since the staff determined that the m}nimum coping duration for an SBO event at the Salem plant is 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (See Section 2.1), the licensee sh~uld verify that the ventilation is adequate for equipment operability for an 8-hour SBO event.

In addition, the licensee should verify that the plant will have sufficient staff to perform the above cited operator actions within 30 minutes following an SBO event and that these operator actions are incorporated in the SBO response procedure in accordance.with the guidance described in NUMARC 87-00.

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• 2.2.5 Containment Isolation The licensee stated that the containment isolation valves have been reviewed to verify that containment isolation valves that must be capable of being closed or operated during an SBO event can be positioned with indication independent of the unit's preferred and Class lE AC power supply.

No modifications and/or associated procedure changes will be required to ensure that appropriate containment integrity can be provided during an SBO event.

Based on its review, the staff concludes that the containment isolation valve design and operation at the Salem plant meet the intent of the guidance described in R.G. 1.155 and are, therefore, acceptable.

2.3 Reactor Coolant Inventory The licensee stated that a plant-specific analysis was used to assess the ability to maintain adequate reactor coolant system (RCS) inventory to ensure that the core is cooled for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

For determining the reactor coolant inventory and condensate inventory, the licensee used both the RETRAN 02 Mod 5 and MAAP Version 3 Mod 2 transient system thermal-hydraulic computer codes.

A review of the licensee's submittals for the RETRAN and MAAP analyses shows a significant contrast between the quality assurance and applicability of these two calculations. While the MAAP analysis includes documentation demonstrating detailed verification and approval of the calculation along with model modification discussions, no such evidence is presented for the RETRAN analysis. Therefore, based on the aforementioned evalu&tions, only the MAAP calculation results are considered applicable to the Salem SBO coping assessment.

Assuming a reactor coolant system leakage of 112 gpm (25 gpm per reactor coolant pump for four pumps and 12 gpm technical specification of other leakage as identified by the licensee), the licensee's MAAP analysis for an 8-hour

• period shows core uncovery occurring at 5.6 to 6.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />. Therefore, the plant cannot cope with an SBO event of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> without additional RCS make-up.

The 25-gpm RCP seal leak rate was agreed to between NUMARC and the NRC staff pending resolution of Generic Issue (GI) 23.

If the final resolution of GI-23 defines higher RCP seal leak rates than assumed for the RCS inventory evaluation, the licensee should be aware of the potential impact of this resolution on its analyses and actions addressing conformance to the SBO rule.

Reconvnendation:

The licensee should state how and from where it plans to supplement the RCS inventory in order to keep the core covered and cooled during an 8-hour SBO event.

2.4 Procedures and ~raining The licensee has stated that the appropriate procedures have been reviewed and the changes necessary to meet NUMARC 87-00 guidelines will be implemented.

The proposed procedure modifications were not reviewed by the staff, but the staff expects the licensee to maintain and implement these procedures and any others needed 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 expects the licensee to implement the appropriate training to assure an effective response to the SBO.

2.5 Proposed Modifications The licensee has proposed to modify the Compressed Air System by adding a permanently installed diesel driven air compressor to supply compressed air to the SBO unit and the non-blacked-out unit. The licensee stated that a detailed schedule for this modification will be submitted to the NRC staff upon receipt of approval of the SBO evaluation by the NRC in accordance.with 10 CFR 50.63 (c)(3), and that it expects the schedule will meet the 2-year requirement of 10 CFR 50.63 (c)(4).

• Also, additional modifications may be required to resolve the staff concerns identified in this SE.

Since the staff has determined that an 8-hour coping duration is required for the Salem Generating Station, the licensee may want to consider an alternate ac (AAC) source to power the SBO equipment.

Recommendation:

The licensee should consider other plant modifications, such as the addition of an AAC source, in order to achieve the required 8-hour coping duration.

2.6 Quality Assurance and Technical Specifications The licensee's has submitted information on quality assurance specifications for SBO equipment consistent with the requirements of RG 1.155, Section 3.5, Appendices A and B.

The Technical Specifications (TS) for the SBO equipment are currently being considered generically by the NRC in the context of the Technical Specification Improvement Program and remains an open item at this time.

However, the staff would expect that the plant procedures will reflect the appropriate testing and surveillance requirements to ensure the operability of the necessary SBO equipment. If the staff later determines that a TS regarding the SBO equipment is warranted, the licensee will be notified of the implementation requirements.

2.7 EOG Reliability Program The licensee's submittal on SBO did not specifically address a connitment to implement an EOG reliability program to conform to the guidance of RG 1.155, Position 1.2, and NUMARC 87-00, Appendix D.

Recommendation:

The licensee should implement an EOG reliability program which meets the guidance of RG 1.155, Section 1.2. If an EOG reliability program currently exists, the program should be evaluated and adjusted in accordance with

• RG 1.155. Confirmation that such a program is in place or will be implemented should be included in the documentation supporting the SBO submittals that is to be maintained by the licensee.

2.8 Scope of Staff Review The SBO 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 for NRC review. The staff and its contractor (SAIC) did not perform a detailed review of the proposed equipment or procedure modifications which are scheduled for later implementation. Therefore, based on our review of the licensee SBO submittal and FSAR, we have identified the following areas for focus in any follow-up inspection or assessment that may be undertaken by the NRC to further verify conformance with the SBO rule:

a.

Hardware and procedural modifications,

b.

SBO 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 minimum the guidelines of RG 1.155,

e.

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

f.

Actions taken pertaining to the specific reco11111endations noted above in this SE.

l JI Additional areas may be identified following staff review of licensee's revised response to the SBO rule.

3.0

SUMMARY

and CONCLUSIONS The staff has reviewed the licensee's responses to the SBO Rule (10 CFR 50.63) and the TER prepared by the staff's consultant SAIC.

Based on the staff's rtview of the licensee's ~ubmittals and the SAIC TER, the staff finds that the Salem Generating Station does not conform with the SBO Rule and the guidance of RG 1.155, and therefore reconunends that the licensee reevaluate the areas of concern that have been identified in this SE.

Guidance for the licensee to revie\\'1 c.rid implement the staff's recommendations is provided in RG 1.155, f\\UMARC 87-00, and the supplementary guidance (NUMARC 87-00 Supplementary Questions/Answers; NUMARC 87-00 Major Assumptions) dated December 27, 1989, which was issued to the industry by NUMARC on January 4, 1990. The staff's concerns that are identified in this SE should be addressed by the licensee, and a revised response submitted to the NRC within 60 days. Since the staff has determined that an 8-hour coping duration is required for the Salem Generating Station, the licensee may want to consider an alternate ac {AAC) source to power the SBO equipment and resolve the staff concerns. The licer.see is expected to ensure that the baseline assumptions of NUMARC 87-00 are applicable to the Salem Generating Plant. Also, the licensee is expected to document all analyses and related information, and verify that these are available for NRC review.

4.0 ATTACHMENT

1.

SAIC-91/1256, Technical Evaluation Report, Salem Generating Station, Station Blackout Evaluation, December 13, 1991.

Principal Contributor N. Trehan Date: