ML18096A388

Final, Technical Evaluation Rept,Salem Generating Station, Station Blackout Evaluation.

ML18096A388
Person / Time
Site:	Salem
Issue date:	12/13/1991
From:	SCIENCE APPLICATIONS INTERNATIONAL CORP. (FORMERLY
To:	NRC
Shared Package
ML18096A389	List: ML18096A388
References
CON-FIN-D-1311, CON-NRC-03-87-029, CON-NRC-3-87-29 SAIC-91-1256, NUDOCS 9112190268
Download: ML18096A388 (28)

Text

TECHNICAL EVALUATION REPORT SALEM GENERATING STATION, UNITS 1 AND 2, STATION BLACKOUT EVALUATION TAC Nos. 68596 and 68597 Science Applications International Corporation Final December 13, 1991 Prepared for: U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Contract NRC-03-87-029 Order No. 38 Attachment 1 SAIC-91/1256

' ,, TABLE OF CONTENTS Section Page 1 . 0 BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.0 REVIEW

PROCESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.0 EVALUATION...........................................

5 3.1 Proposed Station Blackout Duration .............

5 3.2 Station Blackout Coping Capability.............

9 3.3 Proposed Procedures and Training ....... ... .. .. . 20 3.4 Proposed Modifications

.................

... . .... 21 3.5 Quality Assurance and Technical Specifications . 21

4.0 CONCLUSION

S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

22 5. 0 REFERENCES . **........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

25 i i J.

1.0 BACKGROUND

TECHNICAL EVALUATION REPORT SALEM GENERATING STATION, UNITS 1 AND 2, STATION BLACKOUT EVALUATION On July 21, 1988, the Nuclear Regulatory Commission (NRC) amended its regulations in 10 CFR Part 50 by adding a new section, 50.63, "Loss of All Alternating Current Power" (1). The objective of this requirement is to assure that all nuclear power plants are capable of withstanding a station blackout (SBO) and maintaining adequate reactor core cooling and appropriate containment integrity for a required duration.

This requirement is based on information developed under the commission study of Unresolved Safety Issue A-44, "Station Blackout" (2-6). The staff issued Regulatory Guide (RG) 1.155, "Station Blackout," to provide guidance for meeting the requirements of 10 CFR 50.63 (7). Concurrent with the development of this regulatory guide, the Nuclear Utility Management and Resource Council {NUMARC) developed a document entitled, "Guidelines and Technical Basis for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors," NUMARC 87-00 (8). This document provides detailed guidelines and procedures on how to assess each plant's capabilities to comply with the SBO rule. The NRC staff reviewed the guidelines and analysis methodology in NUMARC 87-00 and concluded that the NUMARC document provides an acceptable guidance for addressing the 10 CFR 50.63 requirements.

The application of this method results in selecting a minimum acceptable SBO duration capability from two to sixteen hours depending on the plant's characteristics and vulnerabilities to the risk from station blackout.

The plant's characteristics affecting the required coping capability are: the redundancy of the onsite emergency AC power sources, the reliability of onsite emergency power sources, the frequency of loss of offsite power {LOOP), and the probable time to restore offsite power. In order to achieve a consistent systematic response from licensees to the SBO rule and to expedite the staff review process, NUMARC developed two 1 generic response documents.

These documents were reviewed and endorsed (9) by the NRC staff for the purposes of plant specific submittals.

The documents are titled: I. "Generic Response to Station Blackout Rule for Plants Using Alternate AC Power," and 2. "Generic Response to Station Blackout Rule for Plants Using AC Independent Station Blackout Response Power." A plant-specific submittal, using one of the above generic formats, provides only a summary of results of the analysis of the plant's station blackout coping capability.

Licensees are expected to ensure that the baseline assumptions used in NUMARC 87-00 are applicable to their plants and to verify the accuracy of the stated results. Compliance with the SBO rule requirements is verified by review and evaluation of the licensee's submittal and audit review of the supporting documents as necessary.

Follow up NRC inspections assure that the licensee has implemented the necessary changes as required to meet the SBO rule. In 1989, a joint NRC/SAIC team headed by an NRC staff member performed audit reviews of the methodology and documentation that support the licensees' submittals for several plants. These audits revealed several deficiencies which were not apparent from the review of the licensees' submittals using the agreed upon generic response format. These deficiencies raised a generic question regarding the degree of licensees' conformance to the requirements of the SBO rule. to resolve this question, on January 4, 1990, NUMARC issued additional guidance as NUMARC 87-00 Supplemental Questions/Answers (10) addressing the NRC's concerns regarding the deficiencies.

NUMARC requested that the licensees send their supplemental responses to the NRC addressing these concerns by March 30, 1990. 2 rt .* 2.0 REVIEW PROCESS The review of the licensee's submittal is focused on the following areas consistent with the positions of RG 1.155: A. Minimum acceptable SBO duration (Section 3.1), B. SBO coping capability (Section 3.2), C. Procedures and training for SBO (Section 3.3), D. Proposed modifications (Section 3.4), and E. Quality assurance and technical specifications for SBO equipment (Section 3. 5) .* For the determination of the proposed minimum acceptable SBO duration, the following factors in the licensee's submittal are reviewed:

a) offsite power design characteristics, b) emergency AC power system configuration, c) determination of the emergency diesel generator (EDG) reliability consistent with NSAC-108 criteria (11), and d) determination of the accepted EOG target reliability.

Once these factors are known, Table 3-8 of NUMARC 87-00 or Table 2 of RG 1.155 provides a matrix for determining the required coping duration.

For the SBO coping capability, the licensee's submittal is reviewed to assess the availability, adequacy and capability of the plant systems and components needed to achieve and maintain a safe shutdown condition and recover from an SBO of acceptable duration which is determined above. The review process follows the guidelines given in RG 1.155, Section 3.2, to assure: a. availability of sufficient condensate inventory for decay heat removal, 3

b. adequacy of the class-IE battery capacity to support safe shutdown, c. availability of adequate compressed air for air-operated valves necessary for safe shutdown, d. adequacy of the ventilation systems in the vital and/or dominant areas that include equipment necessary for safe shutdown of the pl ant, e. ability to provide appropriate containment integrity, and f. ability of the plant to maintain adequate reactor coolant system inventory to ensure core cooling for the required coping duration.

The licensee's submittal is reviewed to verify that required procedures (i.e., revised existing and new) for coping with SBO are identified and that appropriate operator training will be provided.

The licensee's submittal for any proposed modifications to emergency AC sources, battery capacity, condensate capacity, compressed-air capacity, ventilation system, containment isolation integrity, and primary coolant make-up capability is reviewed.

Technical specifications and quality assurance set forth by the licensee to ensure high reliability of the equipment, specifically added or assigned to meet the requirements of the SBO rule, are assessed for their adequacy.

This preliminary SBO evaluation is based upon the review of the licensee's submittals dated April 17, 1989 (12), April 30, 1990 (13), July 30, 1990 (14), March 1, 1991 (15), March 28, 1991 (16), and September 17, 1991 (18), and the information available in the plant Updated Final Safety Analysis Report (UFSAR) (19); it does not include a concurrent site audit review of the supporting documentation.

Such an audit may be warranted as an additional confirmatory action. This determination would be made and the audit would be scheduled and performed by the NRC staff at some later date. 4

3.1 Proposed

Station Blackout Duration Licensee's Submittal The licensee, Public Service Electric and Gas (PSE&G), calculated (12 and 13) a minimum acceptable station blackout duration of four hours for the Salem Generating Station site. The licensee initially stated (12) that no modifications are required to attain the proposed coping duration.

The plant factors used to estimate the proposed SBO duration are: 1. Offsite AC Power Design Characteristics The offsite AC power design characteristic group is "Pl" based on: a. Independence of the plant offsite power system characteristics of "Il/2," b. Estimated frequency of LOOPs due to severe weather (SW) which places the plant in SW group "2," c. Estimated frequency of LOOPs due to extremely severe weather (ESW) which places the plant in ESW group "2," and d. Expected frequency of grid-related LOOPs of less.than one per 20 years. 2. Emergency AC (EAC) Power Configuration Group The EAC power configuration of the plant is "D." Each unit at Salem is equipped with three emergency diesel generators.

Two 5 diesels are necessary to operate safe-shutdown equipment following a loss of offsite power. 3. Target Emergency Diesel Generator (EDG) Reliability The licensee has selected a target EOG reliability of 0.975. The selection of this target reliability is based on having an average EOG reliability greater than 0.95 for the last 100 demands, consistent with NUMARC 87-00, Section 3.2.4. Review of Licensee's Submittal Factors which affect the estimation of the SBO coping duration are: the independence of the offsite power system grouping, the estimated frequency of LOOPs due to SW and ESW conditions, the expected frequency of grid-related LOOPs, the classification of EAC, and the selection of EOG target reliability.

The licensee stated that the independence of the plant offsite power system grouping is "11/2." A review of the Salem UFSAR shows that: 1. All offsite power sources are connected to the plant through one switchyard;

2. There are two independent station power transformers (SPTs) per unit which can be connected to the vital buses; 3. During normal operation, power is provided to two of the three vital buses from one of the two station power transformers (SPTs) f and the remaining bus is powered from the other SPT; Upon loss of power from either SPT, there is an automatic transfer to the remaining SPT. 6

_, Based on the above, the plant independence of offsite power system group is "12." This determination is consistent with the guidance provided in RG 1.155, Table 5. Using data from Table 3-3 of NUMARC 87-00, the expected frequency of LOOPs due to SW conditions place the Salem site in SW Group "2," which is in agreement with what was stated in the licensee's submittal (12). This calculation was performed using multiple rights-of-way among the incoming transmission lines, consistent with Figure 8.2-1 of the plant UFSAR ( 19). Using Table 3-2 of NUMARC 87-00, the expected frequency of LOOPs due to ESW conditions place the Salem site in ESW group 4." The licensee used site-specific data to obtain an ESW grouping of "2." This change in ESW group changes the site offsite power characteristic from "P2" to Pl." The licensee was asked (17) to provide information on the site specific data used to determine the ESW grouping.

Review of the licensee's calculation indicates that the frequency of ESW conditions were estimated (18) based on a height of 10 meters above the ground. Figure 8.2-1 of the plant UFSAR (19) shows transmission lines well over 30 meters above ground. Therefore, the calculation should be normalized, at a minimum, to 30 meters. A windspeed of 125 mph normalized to 30 meters is equivalent to a windspeed of 104 mph normalized to 10 meters Using Table 3-2 of the licensee's submittal (18) with a windspeed of 104 mph yields an ESW probability of 3.98 E-3. This probability places the Salem site in ESW group "4" in accordance with Table 3-1 of NUMARC 87-00 and is in,close agreement with the NRC data contained in Table 3-2 of NUMARC 87-00, which lists an ESW probability of 3.80 E-3 for the Salem site. Therefore, we conclude that the licensee has incorrectly classified the site as ESW group "2," and that the correct classification is ESW group "4." With regard to the expected'frequency of grid-related LOOPs at the site, we can not confirm the stated results. The available information in NUREG/CR-3992 (3), which gives a compendium of information on the loss 7

) I I I of offsite power at nuclear power plants in the U.S., covers these incidents through the calendar year 1984, does not identify any grid related LOOPs for the Salem station. In the absence of any contradictory information, we agree with the licensee's statement.

The licensee has incorrectly categorized the offsite AC power design characteristic as group "Pl. Based on an independence of offsite power group "Il/2," an SW group "2," an ESW group 11 4," and an expected frequency of grid-related LOOPs of less than one per 20 years, the correct offsite power design characteristic of the Salem Generating Station is "P2." The licensee correctly categorized the EAC classification of Salem as "O." Each unit has three dedicated EOGs, two of which are necessary to safely shut down the reactor. The licensee selected the EOG target reliability of 0.975 based upon the unit average EOG reliability data for the last 100 demands. The target EOG reliability which the licensee selected (12) and committed to maintain (13) is in conformance with both RG 1.155 and NUMARC 87-00. Although this is an acceptable criterion for choosing an EOG target reliability, the guidance in RG 1.155 requires that the EOG reliability statistics for the last 20 and 50 demands also be calculated.

Without this information, it is difficult to judge how well the EOGs have performed in the past and if there should be any concern. The licensee should have an analysis showing the EOG reliability statistics for the last 20, So, and 100 demands in its SBO submittal supporting documentation.

Although the licensee is committed to maintain the target EOG reliability, it did not state whether the plant has a formal EOG reliability program consistent with the guidance of RG 1.155, Regulatory Position 1.2, and NUMARC 87-00, Appendix D. 8 I L -* A "P2" offsite power design characteristic, in conjunction with an EAC configuration group "D" designation, requires an EOG target reliability of 0.975, with a minimum coping duration of eight hours. In the following sections, we have assessed the Salem Generating Stations ability to cope with an eight hour SBO. 3.2 Station Blackout Coping Capability The licensee provided documentation supporting plant coping capability for four hours. We conclude that the plant needs to cope with an eight hour SBO event. Therefore, our review of the plant coping capability is based on an eight hour SBO and is assessed with the following results: 1. Condensate Inventory for Decay Heat Removal Licensee's Submittal The licensee stated {16) that the minimum usable Technical Specification coolant inventory in the auxiliary feedwater storage tank {AFWST) is 192,069 gallons. The licensee presented

{18) RETRAN and MAAP computer code analyses which show that, for all postulated scenarios during an SBO event, the coolant required for a four hour period will be less than 192,069 gallons. The licensee stated {16) that: 75,451 gallons are needed for decay heat removal for four hours, 54,926 gallons are needed for cooldown, and 38,490 are needed to replenish the level shrink in the steam generators, for a total of 168,867 gallons. For the calculation of required condensate inventory, the licensee used both the RETRAN 02 Mod 5 and MAAP Version 3 Mod 2 transient system thermal-hydraulic computer codes. Both analyses show that* the core is never uncovered during any postulated SBO event for a four hour period. The licensee performed a sensitivity analysis using MAAP by changing assumptions and the duration.

Two of the MAAP runs, case No. 2A and No. 2E, show core uncovery commencing 9

r , I

• at 5.6 and 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. In addition, one MAAP run, case No. 20, indicates that about 205,000 gallons of AFWST would be required for an eight hour SBO coping period. Review of Licensee's Submittal Using the equation provided in NUMARC 87-00 (assuming no cooldown), we estimated that 75,451, and 121,261 gallons of water per unit would be required to remove decay heat during a four and an eight hour SBO event, respectively.

These estimates are based on the maximum licensed core thermal rating of 3411 MWt per unit listed in the Salem UFSAR (19). Without cooldown the AFWST coolant requirement is less than the 192,069 gallons available per technical specifications.

However, the licensee following the SBO procedure may need to cool down and*depressurize the primary system to reduce the reactor coolant system (RCS) leakage, therefore, additional condensate would be needed. The cooldown would add approximately 93,416 gallons of water, requiring a total of 214,677 gallons of condensate for an eight hour SBO event. This volume of water exceeds the minimum Technical Specification quantity of usable condensate available in the AFWST. Therefore, if a cooldown is attempted the plant will not have sufficient condensate to cope with an SBO of eight hours. 2. Class-IE Battery Capacity Licensee's Submittal The licensee stated (16) that a battery capacity calculation has been performed which verifies that the 28 V class-IE batteries have sufficient capacity to meet SBO loads for four hours. The licensee added that the duty cycle includes the AC power restoration loads at the most limiting time in the battery duty 10

'_1 cycle. The licensee also stated (16) that the 125 V class-IE batteries have sufficient capacity to carry the necessary loads for a four 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. The licensee stated (16) that, in the calculations, it used an aging factor of 1.25, a design margin of 1.1, and the lowest temperature anticipated under normal plant operating conditions.

The licensee used minimum terminal voltages of 105 VDC and 19.2 VDC for the 125 and 28 VDC batteries, respectively.

The licensee determined that the minimum excess capacity over the 1.1 design margin for any battery is 6.6% (Battery lC). All of the other batteries have a minimum of 10% capacity above the design margin of 1.1. The licensee provided calculations (18), in response to a request (17), which show that the battery capacity is adequate for the four hour SBO coping duration.

Review of Licensee's Submittal The batteries need to provide the normal plant monitoring and control for the entire SBO duration of eight hours. According to the Salem UFSAR (19) the batteries are sized for two hours of operation-after a loss of AC power. Based on a review of the licensee's battery capacity calculations for SBO loads, we conclude that the licensee's assumed temperature correction factor of 1.08 (based on an electrolyte temperature of 65°F), a design margin of 1.1, and an aging factor of 1.25 are consistent with the IEEE Std-485 guidance.

The licensee's battery calculations (18) support an SBO coping duration of four hours. 11 Information submitted by the licensee (I8) to support the battery calculations for the four hour coping duration was used to determine the battery capacity for an eight hour coping duration.

The calculations for the eight hour coping duration were performed in accordance with IEEE Std-485 using a temperature correction factor, design margin, and aging factor consistent with the values chosen by the licensee.

The calculations assume that the 238 minute continuous discharge period used by the licensee for the four hour coping duration is extended to 478 minutes for the eight hour coping duration.

Our results indicate that all A, B, and C channels for the I25 VDC batteries and the IA and 2A channels for the 28 VDC batteries do not have sufficient capacity to last for the eight hour coping duration under the load conditions specified by the licensee for the four hour coping duration.

The licensee may wish to verify these results. The photocopies of the licensee's graphs that were used to determine amperes per positive plate were somewhat illegible.

We conclude that the class-IE Batteries do not have adequate capacity to support the SBO loads, under licensee specified load conditions, for an eight hour SBO coping duration.

3. Compressed Air Licensee's Submittal The licensee initially stated (I2) that air-operated valves relied upon to cope with a station blackout for four hours have sufficient back-up sources independent of the unit's preferred and class-IE power supply. The initial analysis took credit for the non-blacked out unit's emergency control air compressor to supply compressed air to the SBO unit. The licensee later determined (I3) that application of the single failure criteria to the blacked out unit would eliminate the emergency control air compressor as a source of compressed air to the SBO unit and stated (15 and 16), that units 1 and 2 require a modification to 12

-* the compressed air system in order to cope with the SBO event for the required four hour coping duration.

An evaluation of options (18) to modify the compressed air system to provide control air to vital components required to cope with and recover from an SBO event was performed and provided per request (17). The licensee has stated (18) its intent to install a permanent diesel driven air compressor to provide air to the SBO unit and the non-blacked out unit. Review of Licensee's Submittal The licensee identified (16) the Auxiliary Feed Water (AFW) pump turbine governor and associated control valves and the Atmospheric Relief Valves as the air operated valves necessary for decay heat removal during an SBO. The loss of control air causes the AFW pump flow control valves to fail in the open position.

The licensee stated (18) that an evaluation has been performed which establishes that without any operator intervention, the fail safe AFW system provides sufficient cooling water flow to the steam generators during the first hour of the SBO event. The generated steam is vented to the atmosphere by opening the atmospheric relief valves which fail closed on loss of control air. Local manual operation or a control air source is necessary for valve opening. The licensee stated (18) that the compressed air system will be modified by adding a diesel-driven air compressor.

The licensee stated that the diesel-driven air compressor would be sized (600 SCFM @ 125 psig) to meet both the requirements of the SBO and non-blackout units. This capacity exceeds that of the emergency control air compressor (500 SCFM@ 110 psig). This modification to the control air system should enable the licensee to meet the compressed air requirements for the SBO coping duration.

13

' ' I 4. --Effects of Loss of Ventilation Licensee's Submittal The licensee stated (16) that it has performed a plant-specific analysis to determine the effects of loss of ventilation and concluded that the dominant areas of concern (DACs) and their associated temperatures were: T E M p E R AT u R E °F Room Initial Final Control Room (Doors Closed) 99.9 132.3 Control Room (1 Door Open) 99.9 106.9 Control Room (2 Doors Open) 99.9 96.0 Turbine Driven AFW Pump Area 105. 256.l TDAFW Pump Area (1 Door Open) 105. 177. 9 Electric Driven AFW Pump Area 105. 137.3 MS Outer Penetration Area 115. 211. 5 MS Inner Penetration Area 122. 209.3 Control Equip. Room 76. -93.

• 114.8 480V SWGR Room 105.-119.5* 113. 9 4KV SWGR Room 105.-119.5* 111.8 Elec. Penetration Area 112. 112 .3 Relay/Inverter Room 76.-105.* 121. 5 Battery Room 109.5 116. 5

• The temperature range represents the minimum and the maximum wall surface temperature of each room. The minimum temperature is the inside wall surface temperature.

The NUMARC 87-00 methodology was explicitly used for all aspects of the room heat-up calculation including heat-load determination, initial conditions, assumptions, and actual temperature determination.

In some cases, room temperature response was calculated using the equations in Appendix E of NUMARC 87-00 rather than the more simplified relationships in Section 7.2.4 of 14 NUMARC 87-00. For those DACs with calculated temperatures greater than 120°F, the methods described in Appendix F of NUMARC 87-00 were used by the licensee to show that all equipment within these rooms which would be needed during an SBO event will function.

The licensee also provided a list of seven operator actions which need to be performed within thirty minutes of an SBO event to ensure acceptable room temperatures.

These actions are: I. 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 corridbr from the watch engineer's

5. Open return damper from watch engineer's office to NBO unit EACs. 6. De-energize computer inverter IA in the data logging room. 7. Open door between electric driven and turbine driven AFW pump cubicles.

Review of Licensee's Submittal The licensee provided (18) a complete and detailed calculation files of all aspects of the SBO room heat-up analyses.

The NUMARC 87-00 methodology was correctly applied throughout these calculations.

Each calculation was legible, well organized and . logically provided input for a subsequent calculation.

Inputs and assumptions were selected in accordance with the guidance in 15

' ' I NUMARC 87-00 and were based on conservative parameter values. Documentation included evidence that each calculation was reviewed and approved not only by the contractor, but also by the licensee.

We reviewed specific calculations throughout the documentation provided and found no errors in mathematics, methodology, or result interpretation.

The use of NUMARC 87-00 equations from Appendix E were sometimes supplemented by other equations from commonly used heat transfer textbooks and found to be appropriate and conservative.

This review included such aspects as heat load determination, room heat slab calculation, room temperature response, and equipment operability.

We concur with the licensee, and conclude that plant ventilation, with the operator actions described, is adequate for equipment operability for an SBO coping duration of four hours. However, the NUMARC 87-00 methodology used by the licensee to calculate SBO room heat-up.assumes a constant wall temperature.

This assumption may not yield valid results when calculating room heat-up for an eight hour coping duration.

The licensee needs to verify that ventilation is adequate for equipment operability for an eight hour SBO coping duration.

The licensee provided (18} a list of seven operator actions that would be required to be performed within 30 minutes of an SBO event to assure that room temperatures stay within the acceptable range. Considering the number of actions and their different locations within the plant, the licensee needs to present evidence that the minimum available staff during an SBO event would be sufficient to perform these actions within 30 minutes of an SBO event without undue stress or a reduction of staff performing other SBO event duties simultaneously.

The licensee needs to verify that these operator actions are incorporated in station blackout response procedures per NUMARC 87-00, Section 4.2.1. 16

, ' ' 5. Containment Isolation Licensee's Submittal The licensee stated (I2) that the list of plant containment I isolation valves (CIVs) has been reviewed to verify that valves which must be capable of being closed or that must be operated {cycled) under station blackout conditions can be positioned (with indication) independent of the unit's preferred and class-IE AC power supplies.

The licensee added that no modifications and/or associated procedure changes were determined to be required to ensure that appropriate containment integrity can be provided under SBO conditions.

Review of Licensee's Submittal The licensee provided an analysis (IS), in response to a request for information (I7), of the CIVs and identified those valves (CV68, CV69, and, CVII6) that will require manual action for operation during an SBO event. Valves CV68, CV69, and, CVI16, are manually closed by procedure during an SBO event. Valve CV284, is located inside containment, and need not be closed as it is in series with CVII6. The analysis was performed in accordance with the criteria delineated in NUMARC 87-00 and RG I.I55 using the CIVs identified on Table 6.2-IO of the salem UFSAR (I9). The licensee noted that the valve numbers listed in the analysis were taken from the plant Technical Specifications table for Unit I, and that the table for Unit 2 is not available to verify similarity.

Table 6.2-IO of the UFSAR states that the valve designations are similar. We concur with the licensee's statement

{I2) that all CIVs which must be capable of being closed or be operated (cycled) during the SBO coping duration can be positioned

{with indication) independent of the preferred and the unit's class-IE power supplies.

I7

\ ' I ' 6. Reactor Coolant Inventory Licensee's Submittal The licensee stated (12) that the ability to maintain adequate reactor coolant system (RCS) inventory to ensure that the core is covered and cooled has been assessed using plant-specific analyses.

The licensee determined that the resultant leak would not result in core uncovery during a 4-hour SBO event. For determining the reactor coolant inventory and the condensate inventory, the licensee used both the RETRAN 02 Mod 5 and MAAP Version 3 Mod 2 transient system thermal-hydraulic computer codes. RETRAN is a widely used code among utilities which was developed under EPRI sponsorship.

The licensee used a simplified single loop model to analyze several SBO scenarios using RETRAN code. The MAAP code was developed to model severe accident phenomena for LWRs and has been extensively used in the nuclear industry for predicting primary and secondary side response to such accidents as well as containment behavior.

Along with time to core uncovery and AFW coolant requirements, MAAP was utilized to investigate the effects of accumulator nitrogen entering the primary system, hydrogen gas evolution and containment thermodynamic response during different SBO scenarios.

Both analyses showed that the core is never uncovered during any postulated SBO event for a four hour period. The licensee performed sensitivity analysis by changing the blackout duration and. input parameters, i.e., reactor pressure, accumulator

• injection, etc. Two of the MAAP runs, case No. 2A and No. 2E show core uncovery commencing at 5.6 and 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. These two cases assume that upon the depletion of the accumulators, the heat transfer from the primary system to the secondary system will seize, due to nitrogen entering the RCS and blocking the steam generator tubes. 18 l !

I ' .1 !' Review of Licensee's Submittal A review of the licensee's RETRAN and MAAP analysis submittals 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.

The RETRAN model was simplified from a model provided to NUS by the licensee.

There is no confirmation that all these model changes were reviewed and approved to ensure that no errors were made. There is no explanation that the specific model simplifications would not detract from the accuracy of RETRAN to calculate key parameters for SBO purposes.

Finally, the inherent limitations of RETRAN which include no ability to model nitrogen or hydrogen in the primary system as well as no containment modelling features further detract from the usefulness of RETRAN calculation results for this application.

MAAP specifically simulates the transport and evolution of non-condensable gases such as nitrogen and hydrogen and includes a containment response model. Therefore, based on the aforementioned evaluation, only the MAAP calculation results are considered applicable to the Salem SBO coping assessment.

Assuming an RCS of 112 gpm {25 gpm per reactor coolant pump for four pumps and a 12 gpm Technical Specification leak), the licensee's MAAP analyses for an eight hour period show core uncovery occurring at 5.6 or 6.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />. Therefore, the plant cannot cope with an SBO event of eight hours without additional RCS make-up. The licensee needs to state how and from where it plans to supplement the RCS inventory in order to keep the core covered and cooled during an eight hour SBO event. 19

\ ' ' ' I I "' 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 needs to be aware of the potential impact of this resolution on its analyses and actions addressing conformance to the SBO rule. 3.3 Proposed Procedures and Training Licensee's Submittal The licensee stated (12) that plant procedures have been reviewed and changes necessary to meet NUMARC 87-00, will be implemented in the following areas: 1. Station Blackout response, {PSE&G Procedure 1(2)-EOP-LOPA-l) per NUMARC 87-00 Section 4.2.1; 2. AC power restoration, (PSE&G Procedures Electric Restoration Plan/June 1986, and 1(2)-EOP-LOPA-l) per NUMARC 87-00, Section 4.2.2; and 3. Severe weather, {PSE&G Procedure AOP-WIND-1) per NUMARC 87-00, Section 4.2.3. Review of Licensee's Submittal We neither received nor reviewed the affected procedures.

We consider these procedures to be plant-specific actions concerning the required activities to cope with an SBO. It is the licensee's responsibility to revise and implement these procedures, as needed, to mitigate an SBO event and to assure that these procedures are complete and correct, and that the associated training needs are carried out accordingly.

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\ ' . 1 I .. 3.4 Proposed Modification Licensee's Submittal The licensee has proposed to modify the Compressed Air System by adding a permanently installed diesel driven air compressor (18) to supply compressed air to the SBO unit and the non-blacked-out unit. The licensee stated (18) 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 the schedule is expected to meet the two year requirement of 10 CFR 50.63 (c)(4). Review of Licensee's Submittal The addition of a permanently installed diesel driven air compressor should allow the licensee to supply compressed air for the eight hour SBO coping duration.

However, the licensee needs to consider other plant modifications in order to achieve the required eight hour coping duration.

It is the licensee's responsibility to ensure that any modifications comply with the SBO guidance.

3.5 Quality

Assurance and Technical Specifications The licensee has submitted (18) information on quality assurance specifications for SBO equipment which demonstrates compliance to the guidance of RG 1.155, Section 3.5 and Appendices A and B. 21

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4.0 CONCLUSION

S Based on our review of the licensee's submittals and the information available in the UFSAR for Salem Generating Station, Units 1 and 2, we find that the submittal conforms with the requirements of the SBO rule and the guidance of RG 1.155 with the following exceptions:

1. Proposed Station Blackout Duration The licensee proposed an SBO coping duration of four hours, based on ESW group "2," which resulted in classifying the units as "Pl." Our review indicates.that the Salem site is in ESW group "4, and group "P2." This offsite AC power design characteristic, in conjunction with an EAC group "O" classification requires an EOG reliability target of 0.975 (as chosen by the licensee), and a minimum coping duration of eight hours, see Section 3.1. 2. Emergency Diesel Generator Reliability The licensee needs to have an analysis showing the EOG reliability statistics for the last 20, 50, and 100 demands in its SBO submittal supporting documentation.

In addition, the licensee is committed to maintain the target EOG reliability and needs to have a formal reliability program consistent with the guidance provided in RG 1.155, Regulatory Position 1.2. 3. Condensate Inventory Our review indicates, that if a cooldown is attempted, the plant will not have sufficient condensate to cope with an SBO of eight hours. 22

, , I I J " * ' 1 I .-4. Class-IE Battery Capacity Our review concludes that the class-IE Batteries do not have adequate capacity to support the SBO loads, under licensee specified load conditions, for an eight hour SBO coping duration.

5. Effects of Loss of Ventilation Our review of the information submitted by the licensee indicates that room temperatures in DACs should be within acceptable ranges necessary to assure operability of equipment needed for a hour SBO coping duration.

However, the licensee needs to verify that room temperatures in DACs are adequate for equipment operability for the required eight hour SBO coping duration (see Section 3.2, item 4). In addition, the licensee needs to evaluate the ability of the minimum allowable staff to perform the operator actions required to maintain the DAC's within acceptable ranges under SBO conditions.

The licensee needs to verify that these operator actions are incorporated in the station blackout response procedures.

6. Reactor Coolant Inventory Our review indicates that additional RCS make-up will be needed for the plant to cope with an eight hour SBO event. The licensee needs to state how and from where it plans to supplement the RCS inventory in order to keep the core covered and cooled. 7. 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. 23

'-I I _, In addition, our review of the licensee's submittals have identified (see items 1 through 7 above) that may require other modification(s) or changes to existing equipment to enable the plant to achieve an eight-hour SBO coping duration.

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5.0 REFERENCES

1. The Office of Federal Register, "Code of Federal Regulations Title 10 Part 50.63," 10 CFR 50.63, January 1, 1989. 2. U.S. Nuclear Regulatory Commission, "Evaluation of Station Blackout Accidents at Nuclear Power Plants -Technical Findings Related to Unresolved Safety Issue A-44," NUREG-1032, Baranowsky, P.W., June 1988. 3. U.S. Nuclear Regulatory Commission, "Collection and Evaluation of Complete and Partial Losses of Offsite Power at Nuclear Power Plants," NUREG/CR-3992, February 1985. 4. U.S. Nuclear Regulatory Commission, "Reliability of Emergency AC Power System at Nuclear Power Plants," NUREG/CR-2989, July 1983. 5. U.S. Nuclear Regulatory Commission, "Emergency Diesel Generator Operating Experience, 1981-1983," NUREG/CR-4347, December 1985. 6. U.S. Nuclear Regulatory Commission, "Station Blackout Accident Analyses (Part of NRC Task Action Plan A-44), 11 NUREG/CR-3226, May 1983. 7. U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research, "Regulatory Guide 1.155 Station Blackout," August 1988. 8. Nuclear Management and Resources Council, Inc., "Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors," NUMARC 87-00, November 1987. 9. Thadani, A. C., Letter to W. H. Rasin of NUMARC, "Approval of NUMARC Documents on Station Blackout (TAC-40577), 11 dated October 7, 1988. 10. Thadani, A. C., letter to A. Marion of NUMARC, "Publicly-Noticed Meeting December 27, 1989, 11 dated January 3, 1990, (Confirm.ing "NUMARC 87-00 Supplemental Questions/Answers," December 27, 1989). 25

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• I' ' 11. Nuclear Safety Analysis Center, "The Reliability of Emergency Diesel Generators at U.S. Nuclear Power Plants," NSAC-108, Wyckoff, H., September 1986. 12. LaBurna, S., letter to NRC Document Control Desk, "Station Blackout Coping Analysis Salem Generating Station Unit Nos. 1 and 2," Docket Nos. 50-272 and 50-311, dated April 17, 1989. 13. Crimmins, T. M. Jr., letter to NRC Document Control Desk, "Station Blackout Supplemental Response Salem and Hope Creek Generating Stations," Docket Nos. 50-272, 50-311, and 50-354, dated April 30, 1990. 14. Crimmins, T. M. Jr., letter to NRC Document Control Desk, "Station Blackout Schedule Commitment Salem and Hope Creek Generating Stations, 11 Docket Nos. 50-272, 50-311, and 50-354, dated July 30, 1990. 15. Crimmins, T. M. Jr., letter to NRC Document Control Desk, "Station Blackout Revised Schedule Salem and Hope Creek Generating Stations," Docket Nos. 50-272, 50-311 and 50-354, dated March 1, 1991. 16. Crimmins, T. M. Jr., letter to NRC Document Control Desk, "Station Blackout Revised Coping Analysis Salem Generating Station Units 1 and 2," Docket Nos. 50-272 and 50-311, dated March 28, 1991. 17. Stone, J.C., letter to Public Service Electric & Gas, "Station Blackout, Request for additional Information, Salem Nuclear Generating Station, Units l and 2 (TAC NOS. 68596 AND 68597)," dated August 13, 1991. 18. Crimmins, T. M. Jr., letter to NRC Document Control Desk, "Response to Station Blackout Request for Additional Information Salem Generating Station Unit Nos. l and 2," Docket Nos. 50-272 and 50-311, dated September 17, 1991. 19. Salem Generating Station Updated Final Safety Analysis Report. 26