IR 05000293/1993080

Insp Rept 50-293/93-80 on 931018-23.No Violations Noted. Major Areas Inspected:Station Blackout Coping Sys,Onsite Ac Supplies & Reliability Program,Plant Mods & QA & Maint Practices for Station Blackout Equipment

ML20059D792
Person / Time
Site:	Pilgrim
Issue date:	12/21/1993
From:	Cheung L, Ruland W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20059D783	List: IR 05000293/1993080 ML20059D778
References
50-293-93-80, NUDOCS 9401100084
Download: ML20059D792 (26)

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U. S. NUCLEAR REGULATORY COMMISSION '

l REGION I REPORT / DOCKET NOS. 50-293/93-80 i i

LICENSE N DPR-35 i LICENSEE: Boston Edison Company RFD N Rocky Hill Road .  ;

Plymouth, Massachusetts 02360  ;

FACILITY: Pilgrim Nuclear Power Station INSPECTION DATES: October 18-23, 1993 l l

R. Bhatia, Reactor Engineer, RI- 'l INSPECTORS:

P. Kang, Electrical Engineer, NR D. Kern, Resident Inspector, RI M. Shymlock, Chief, Plant Systems Section,.RII

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TEAM LEADER: , / /

120 nard Cheung, Sr. Reactor Egneer ' Da(e Electrical Section, EB, DRS l APPROVED BY: A William H. Rulind,' Chief '

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Electrical Section, EB, DRS l l

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9401100084 931223 PDR ADOCK 05000293 O PDR

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SUMMARY This was the second station blackout inspection conducted by the Region I staff. The team used temporary instruction TI 2515/120 as guidance for conducting this inspection. The ,

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actions taken to implement the station blackout rule are important because many of the systems required for decay heat removal and containment culing are dependent on the availability of alternating current (ac) power. In the event of a station blackout, relatively few systems that do not require ac power are depended upon to remove decay heat, until ac power is restored. The consequence of the failure of this equipment to operate could be severe. The objective of this inspection was to verify through inspection the adequacy of the

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programs, procedures, training, equipment, and systems for implementing the station blackout rule. Specifically, the team reviewed the station blackout coping duration, the station blackout coping systems, plant modifications, emergency diesel generator and alternate ac (AAC) source reliability programs, quality assurance and maintenance for station blackout (SBO) equipment, SBO procedures, and training. The team also reviewed the interface of the 23 kV system with the AAC sourc The team's review of the coping duration analysis indicated that the SBO duration of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> ,

for Pilgrim was in accordance with the criteria specified in Regulatory Guide (RG) 1.15 For the SBO coping systems, the team concluded that: 1) Pilgrim had sufficient condensate inventory to cope with an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> SBO duration; 2) all areas which contained equipment needed for SBO coping had proper cooling; 3) there was sufficient evidence that the torus temperature and the reactor vessel conditions would be maintained according to the plant Technical Specifications; 4) the overall communications capability available during an SBO ,

were adequate; and 5) that adequate emergency lighting was available to support plant personnel operations during a station blackou l

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The team concluded that Pilgrim's EDG reliability program included appropriate elements and activities to ensure that the selected reliability level was maintained in accordance with the Reliability Program outlined in RG 1.155, and that Pilgrim's AAC source generally met ,

the criteria of NUMARC 87-00, Appendix B, and the guidance of RG 1.155, except that: 1)

the reliability of the SBO disel generator (DG) did not meet NUMARC 87.00, Appendix B, 4 Criterion B.13, and 2) BECo had not yet implemented a comprehensive maintenance program as specified in NUMARC 87.00, Appendix B, Criterion B.l For plant modifications, the team concluded that: 1) SBO diesel generator and the circuit

breakers required for proper alignment were properly installed; 2) post-modification tests were adequately executed; 3) preoperational tests were conducted in accordance with test procedures, and properly demonstrated equipment capability. The team determined that BECo had implemented all SBO modifications for the alternate ac power source identified in the Pilgrim SBO safety evaluation repor iv

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For quality assurance and maintenance practices, the team concluded that proper quality assurance (QA) and maintenance controls wem in place to provide reasonable assurance that the SBO DG would be available and function as designed in the event of an SBO, and that generally, BECo has a good maintenance practice for the AAC system, including interface equipment with the SBO DG. However, BECo had not yet established a comprehensive maintenance program for the SBO D The team determined that operators were effectively trained and staffing levels were appropriate to cope with an SBO and establish long-term core coolin ,

During the team's review of the 23 kV system, the team identified two unresolved items in that area. These two items are: 1) lack of degraded voltage protection when the emergency buses are powered by the 23 kV source; and 2) lack of quality documentation for the 23 kV transmission line for General Design Criterion (GDC) 17 applicatio The inspection findings are summarized as follows:

Four Unresolved Items Discussed in Paracraph Item N . SBO diesel generator 2. maintenance program SBO diesel generator reliability 2. ! Lack of degraded voltage protection :

when emergency buses are powered by the 23 kV sourc j i

' Lack of quality documentation for the kV transmission lin v

I DETAILS INSPECTION BACKGROUND / OBJECTIVE .

A station blackout (SBO) is the complete loss of alternating current (ac) electric power (loss

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l of all offsite power concurrent with a turbine trip and the unavailability of both emergency diesel generators) to the essential and nonessential switchgear buses in a nuclear power plan Because many safety systems required for reactor core decay heat removal and containment heat removal are dependent on ac power, the consequences of a station blackout could be severe. To address this concern, the Commission issued in 1988, the Station Blackout Rule, 10 CFR 50.63, " Loss of All Alternating Current Power." To pmvide guidance on acceptable methods for meeting the requirements of the station blackout rule, the NRC issued Regulatory Guide 1.155, " Station Blackout." Concurrent with the development of the regulatory guide, the Nuclear Management and Resource Council (NUMARC) developed guidelines and procedures for assessing station blackout coping capability and duratio NUMARC 87-00, " Guidelines and Technical Bases for NUMARC Initiatives Addressing

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Station Blackout at Light Water Reactors," documents the NUMARC recommendations. The team used these documents for inspection guidanc .

Boston Edison Company (BECo) provided the NRC the Pilgrim Nuclear Power Station (Pilgrim) response to the station blackout (SBO) rule in a letter dated April 17,1989, and subsequent letters dated March 28,1990, and August 31,199 The NRC issued a safety evaluation report (SER) of the Pilgrim response to the SBO rule on February 13, 1991. The SER presented several recommendations, but concluded that Pilgrim Station conforms with the SBO rule. BECo responded to the SER recommendations in two letters to the NRC dated March 26,1991, and June 3,1991. A supplementary safety evaluation report (SSER) was issued on January 15, 1992. BECo responded to the SSER in a letter dated February 6,1992. The NRC found BECo's response to be acceptable and issued a letter on March 5,1992, to close out the SBO issues. On August 30,1993, BECo sent a letter (BECo 93-117) to the NRC, stating that all planned actions to fully comply with "

the SBO rule were complete as of July 31,199 In response to the SBO rule, Pilgrim utilized an already-installed non-Class 1E diesel generator as an alternate alternating current (AAC) soarce for SBO coping. Additional modifications, such as breaker alignment and control logic changes were accomplished to upgrade the source to meet the recommendations and criteria of Regulatory Guide 1.155 and NUMARC 87-00. The AAC was demonstrated by testing to be capable to power all SBO loads.

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This was the second station blackout inspection conducted by the Region I staff. The team used temporary instruction TI 2515/120 as guidance for conducting this inspection. The actions taken to implement the station blackout rule are important because many of the systems required for decay heat removal and containment cooling are dependent on the availability of alternating current (ac) power. In the even of a station blackout, relatively few systems that do not require ac power are depended upon to remove decay heat, until ac power is restored. The consequence of the failure of this equipment to operate could be sever The objective of this inspection was to verify through inspection the adequacy of the programs, procedures, training, equipment, and systems for implementing the station blackout rule. Specifically, the team reviewed the station blackout coping duration, station blackout coping systems, plant modifications, emergency diesel generator (EDG), and AAC source reliability programs, quality assurance, and maintenance for SBO equipment, SBO procedures, and training. The team also reviewed the interface of the 23 kV system with the AAC source. The details of the inspection findings are discussed in Sections 2.1 through .0 DETAILED INSPECTION FINDINGS Station Blackout Coping Duration The station blackout rule requires that the station blackout coping systems provide sufficient capacity and capability to ensure that the core is cooled and appropriate containment integrity is maintained in the event of a station blackout (SBO) for the specified duration. The specified duration was selected based on factors such as the offsite power design characteristics, emergency alternating current (ac) power supply configuration, and the emergency diesel generator (EDG) reliability. A minimum acceptable SBO duration for the Pilgrim was determined to be 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The team reviewed the selected factors, which were j used in determining the 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> SBO duratio Initially, BECo had calculated a minimum acceptable SBO duration of 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> but changed it to 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 P2, an emergency ac configuration group of C, and an EDG reliability target of 0.975. The P2 grouping was j based on an independent of offsite power classification of group 13, a severe weather (SW)

! classification of group 2, and an extremely severe weather (ESW) classification of group l

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BECo's selection of the SW group 2 was based on their recent modification made on the switchyard (e.g., applying Sylgard to circuit breaker insulator) which would reduce the salt

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spray related offsite power loss. However, BECo did not submit sufficient data to support the SW group 2 selection. After reviewing the available information submitted by BECo, the

NRC determined that the SW group should be remained at 4. On this basis, the NRC i concluded that the offsite power design characteristic group of the Pilgrim site should be P3 i

rather than P2, with a minimum required SBO duration of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

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During this inspection, the team discussed with BECo personnel who worked on the SBO ,

i j evaluation to verify that the above selections of SBO factors were appropriate. As an '

j example, the team questioned whether the Pilgrim offsite power group should be II instead l

of I3 (Regulatory Guide 1.155 group) and will it have any impact on the selection of the 8 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> SBO duration. BECo explained that it could have been "II," but selectal group 13 (the

! worst offsite power configuration allowed) just to be conservative.

i j The team also reviewed the most recent EDG reliability data prepared in accordance with 4 NUMARC 87-00, Rev.1, Appendix D, and found that the Pilgrim EDG reliability indicator j as of September 29,1993, was within 0.975 NUMARC Trigger Values (Non-Exceedance).

4 The team determined that the selection of a 0.975 EDG reliability target value was j appropriat *

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i The team concluded that the SBO duration of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> was appropriate and in accordance with q

the critena specified in Regulatory Guide 1.155.

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' Station Blackout Coping Systems

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In their submittal to the NRC for compliance with the SBO rule, BECo committed that the alternate ac (AAC) power source at Pilgrim would be available within 10 minutes to power

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j at least one safety train of normal safe shutdown systems and equipment. Therefore, BECo 4 was not required to perform a detailed coping analysis consistent with 10 CFR 50.63 (C)(2).

j BECo was also not required to perform any additional calculations concerning the station ;

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j battery capacity, compressed air, and containment isolation to meet the requirements of the l SBO rule. However, the Pilgrim SBO safety evaluation (SE), dated January 22,1991, stated that BECo's proposed method of coping with an SBO was acceptable, but subject to the satisfactory resolutions of three recommendations discussed in paragraph 2.2.1 through 2.2.3, 2.2.1 Condensate Inventory for Decay Heat Removal The SE recommended that BECo should estimate the condensate requirements for maintaining reactor coolant system (RCS) inventory during depressurization, and to verify that the site had sufficient condensate inventory for copying with a SBO of 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> duratio ;

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To satisfy this recommendation, BECO performed a calculation, S&SA-70, dated February 13, 1992, entitled " Condensate Makeup Requirements for Station Blackout with Blowdown to 200 psig." The calculation showed that the total reactor coolant required for an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> SBO duration, assuming the reactor will have to be depressurized to 200 psig, is 99, 388 gallons. The two condensate storage tanks (CST) have a reserve of at least 75,000 gallons each for a total of 150,000 gallons which is more than adequate for an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> coping duration. This condensate inventory requirement included the Technical Specifications (TS)

limit of 25 gpm leakage rate to be continued for the duration of the SBO. However, in BECo Calculation S&SA-70, only 18 gpm leakage per recirculation pump seal was considered because: 1) the pump mechanical seal had been installed; 2) the seal leakage was being monitored and alarms in the main control room; and 3) the off-normal Operation Procedure 2.4.22, " Failure of Recirculation Pump Seal," required tripping and isolating the recirculation pumps in the event of seal failure Even if seal failure does occur during a SBO, the isolation valves in the recirculation loops could be closed because the power supply to those valves was fed from the SBO diesel generato The team verified that th ' solation valves in the recirculation loops were powered from the 480 Vac bus B20, via bus B6, which could be fed from either safety buses A5 or A6, which would be available during the SBO after 10 minutes. The team also verified that the power supply to the valves were identified in the SBO load capacity calculation.

t 2.2.2 Effects of Loss of Ventilation Pilgrim SBO SE identifies several areas which contain equipment needed for SBO copin i BECo is required to show that they are not dominant areas of concern. These areas are:

1) reactor and turbine building closed loop cooling pumps 2) vital instrument MG set 3) battery chargers l 4) emergency switchgear rooms  !

5) emergency 4160/480V transformers j I

The team's review of documents provided by BECo indicated that the vital MG set room j l

i temperature could rise to 116.1 F at the end of an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> SBO event. However, this is i below the design temperature of 120*F for the MG se I I

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The team reviewed the heat-up rate calculations for the emergency switchgear rooms that also contain battery chargers and emergency transformers. However, the team was told that J

the calculations to support the worst-case was not yet completed. To ensure the room temperature remains below 104*F, BECo developed a compensatory procedure, No. 2.4.153, j entitled "IAss of Switchgear Area Ventilation." This procedure is to be impicmented when l

the room temperature reaches 95*F at the switchgear areas by establishing natural circulation

ventilation flow path (by opening doors, dampers, and louvers). The team reviewed the i compensatory procedure and did not identify any deficiencie .

BECo evaluated the areas where the reactor and turbine building closed loop cooling pumps were located and determined that they were not dominant areas of concern for the following reasons: ,

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l 1) The rooms housing this equipment are outside the secondary containment.

l 2) These areas are subterranean and therefore are normally moderate in temperatur ) There is no significant high temperature energy source in this large room which has a large free volume.

4) There is no process steam in these room ) The ac loads in theses rooms are light, only one bus is powered by the SBO DG.

l The team reviewed the BECo evaluation and visited the rooms where the reactor and turbine l building closed loop cooling pumps were located and verified the above conditions. No deficiencies were identifie {

2.2.3 Reactor Coolant Inventory l In paragraph 2.3.6 of the Pilgrim SBO safety evaluation report, the NRC recommended that

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"the licensee should ensure that the torus temperature and the reactor vessel conditions are maintained according to the plant Technical Specifications."

The team reviewed the Pilgrim emergency operation procedure EOP-01, entitled " Reactor Pressure Vessel Control." The RPV level leg of this procedure (step L-3) requires the operators to maintain the reactor vessel level within +9" to +48" (much higher than the Technical Specification low limit, i.e., the top of active fuel level) using injection systems (high pressure coolant injection (HPCI) pump and reactor core isolation cooling (RCIC)

pump). These pumps would be available during an SBO because they have their own direct current (de) systems. Since no single failure is assumed during an SBO, the team agreed that I maintaining the reactor vessel level could be accomplished.

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If the reactor vessel pressure cannot be maintained through the steaming process by operating the HPCI and RCIC turbines, the safety relief valves (SRV) will be actuated to maintain the reactor vessel pressure within an acceptable limit. Since the SRV setpoints are Technical Specification items, the team agreed that the reactor vessel pressure could be maintained within the Technical Specifications limit The team also reviewed emergency operation procedure EOP-03, entitled, " Primary

< Containment Control." The torus water temperature leg of this procedure (step 'IT-1)

requires the operator to monitor and control the torus water temperature to below 80*F, using suppression pool cooling. The suppression pool cooling can be achieved using a service water pump and a residual heat removal (RHR) pump, which were included in the SBO diesel generator load calculation. Since there is a wide margin between 80 F and the Technical Specification limit of 120 F, the team determined this explanation to be acceptabl The team determined that there was sufficient evidence that the torus temperature and the reactor vessel conditions would be maintained to the plant Technical Specification .2.4 Communications and Emergency Lighting The team reviewed the Pilgrim communication capability when dealing with a station blackout condition. Pilgrim station procedure No. 2.4.57, " Loss of Public Address System,"

Rev. 2, was reviewed. During a station blackout, the Gai-Tronics public address system will not have power. The operators can use the portable radios available in the control room if communication is required. During the walkdown of the station blackout procedures on the simulator with a senior teactor operator, the team found that all actions needed to place the station blackout diesel on the A8 bus and to pickup loads were performed from the control room. The team concluded that the overall communications capability available during a station blackout were adequat BECO's approach to station blackout and procedure implementation requires only limited involvement outside the control room. The team reviewed the adequacy of the emergency lighting systems in those areas where operator actions would be performed. The team determined that adequate emergency lighting, which consisted of battle lanterns and flash lights, was available to cope with a station blackou .2.5 Conclusion The team concluded that Pilgrim had sufficient condensate inventory to cope with an 8-hour SBO duration; that all areas which contained equipment needed for SBO coping had proper cooling; that there was sufficient evidence that the torus temperature and the reactor vessel

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conditions would be maintained according to the plant Technical Specifications; that the overall communications capability available during an SBO were adequate; and that adequate emergency lighting was available to support the plant personnel's operation during a station blackout. Onsite AC Supply Reliability Programs 2.3.1 Emergency Diesel Generator Reliability Program The team reviewed the emergency diesel generator reliability program to verify that the emergency diesel generator reliability data was being trended and that the program was consistent with the NUMARC 87-00 guidance.

Pilgrim's 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> SBO duration was selected based on Pilgrim's offsite power design characteristics and an EDG target reliability of 0.975 in accordance with guidance provided in RG 1.155 and NUMARC 87-00. This target reliability was based on EDGs having an average reliability greater than 0.95,0.94, and 0.90 for the last 100,50, and 20 demands, respectively, as prescribed in C.I.1.3 of RG 1.155.

Pilgrim's EDG Reliability Program was described in Station Procedure No.1.5.16, entitled

" Emergency Diesel Generator Reliability Program," dated December 18, 1991, along with the data collection system that serviced the elements of the reliability program.

The team found that the EDG reliability program included detailed surveillance testing, maintenance, and reliability monitoring programs.

Based on collected information, BECo produced a report, " Quarterly EDG Reliability Program Summary," to identify the exceedance trigger value or problem EDG. In addition, ~

the program identified responsibilities for the major program elements 'and a management oversight program for reviewing reliability level rhe team reviewed the latest " Quarterly EDG Reliability Report Summary" report, dated September 29,1993, for each EDG based on the failures in 20,50, and 100 demands. The report indicated that all target reliability values were met. Therefore, the team concluded that the selected target reliability value of 0.975 was appropriate.

2.3.2 Alternate AC System and Reliability Program The team reviewed the AAC power system and evaluated it against the criteria of NUMARC 87-00, Appendix B. The team found that:

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1) the SBO diesel generator was built as non-Class lE and non-seismic, and protected against likely weather-related events by installing all cables underground. Any severe weather would not simultaneously fail the AAC source and the preferred power source together (criteria B.1, B.2, and B.3).

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2) the AAC power is separated electrically and physically from the preferred offsite source and from the onsite EDG power system (criteria B.4 through B.7).

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3) the AAC is a self-contained system by having a dedicated de system, air starting system, fuel supply (40,000 gallons plus 275 gallons in day tank), and engine cooling system, and is not sharing any components with the EDGs, thus minimizes potential common cause failure with the EDGs (criteria B.8.a, c, and f).

4) Although the SBO DG and the EDG are not identical machines (different size), they shared the same manufacturer (ALCO). BECo evaluated all active failures of the EDG to determine if the required corrective actions were applicable to the SBO DG (Criterion B.8d).

5) BECo installed a keep-warm system for SBO DG lube oil and jacketwater, and '

sampled the lubricating oil quarterly, sampled the fuel oil monthly, and calibrated the instruments every refueling outage (criterion B.8e).

6) BECo tested the SBO DG following maintenance activities before return of the AAC system to service (criterion B.8g).

7) BECo tested the SBO DG for its ability to start and pickup load on emergency bus A6 by loading one control rod drive pump, two residual heat removal pumps, and one core spray pump in accordance with Temporary Procedure No. TP87-267, " Pre- '

operational Test of the Blackout Diesel Generator." BECo alib performed SBO DG loading calculation and voltage drop estimates (discussed in paragraph 2.3.1) and frequency verification (criterion B.9).

8) BECo demonstrated load carrying capability of the SBO DG by performing the surveillance test every three months using Procedure No. 8.9.16.1, " Manually start and Imad Blackout Diesel Via the Shutdown Transformer" (criterion B.10).

9) NUMARC 87-00, Appendix B, Criteria B.11, specifies a maintenance program (procedure) for the AAC system. BECo did not have a comprehensive maintenance program for the SBO DG yet. BECo stated that the SBO rule was implemented only recently; therefore, this program was not yet required. BECo also stated that a j

station maintenance procedure was being developed to implement the maintenance program and expected this procedure to be completed within about three month This is an unresolved item pending NRC verification of BECo's implementation of maintenance program for the SBO DG (50-293/93-80-01).

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10) BECo completed the initial test on May 11,1993, of the operability of the 4160V and 480V cross-tie circuits under SBO conditions using Procedure TP 93-007 to demonstrate AAC system to be capable of powering the required shutdown equipment within 10 minutes of a station blackout event (criterion B.12).

The team reviewed the SBO DG reliability data collected up to September 27,1993. The review was to determine whether the reliability data met the 95% reliability target specified in RG 1.155 and NUMARC 87-00, Appendix B, Criterion B.13. BECo began the SBO DG reliability data collection on April 6,1990. Since then, it had performed 10 surveillance tests (start and load runs). No failums existed prior to May 1993. Since May 1993, BECo performed five tests. Three of the five tests failed. The failures resulted from overfrequency relay trip (connection to electronic speed controller), output breaker trip (mechanical latching relay became unlatched during test), and fuel oil leak (between injector and fuel pump). These failures occurred on May 10, September 13, and September 13, 199 The test frequency for SBO DG was once per year in the first year (1990). Since then, the test frequency was increased to once every 6 months. Recently (September 1993), the test frequency was again increased to once every three months. This was implemented to improve the reliability data of the SBO D Based on this review, the team determined that BECo's test data did not support the 95%

reliability value specified in NUMARC 87-00, Appendix B, Criterion B.13. This item is unresolved pending NRC review of BECo's resolution (50-293/93-80-02).

To enhance the plant's ability to respond to off-normal conditions, and to reduce risk of severe accidents, BECo implemented a safety enhancement program (SEP). Although the operability of the SBO DG is not a part of Pilgrim technical specifications, the SEP requires that, if the SBO DG becomes inoperable, the SBO DG must be restored to operable status within 30 days or place the plant in the hot shutdown condition. This program shows BECo's commitment to maintain the SBO DG at the high level of readines .3.3 Conclusion The team concluded that Pilgrim's EDG reliability program included appropriate elements and activities to ensure that the selected reliability levels were maintained in accordance with the Reliability Program outlined in RG 1.155. The team also concluded that Pilgrim's AAC source generally met the criteria of NUMARC 87-00, Appendix B, and the guidance of RG 1.155, except that: 1) the reliability of the SBO DG did not meet NUMARC 87.00, Appendix B, Criterion B.13, and 2) BECo had not yet implemented a comprehensive maintenance program as specified in NUMARC 87.00, Appendix B, Criterion B.1 !

10 i Plant Modifications The team reviewed four plant modification packages (PDC 86-56A & B, PDC 89-043 and-044) which were used to install the SBO alternate ac system, PDC 86-56A & B for the SBO !

l diesel generator and breaker alignment, PDC 89-043 for the replacement of breaker control switches in the main control board, and PDC 89-044 for the control logic. The review included the SBO diesel generator loading calculation, applicable breaker protection scheme design, breaker ratings, cable ampacity of SBO diesel cable, and post-modification testing

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and preoperation testing. BECo committed, in their submittal to the NRC, to complete these l modifications to satisfy the Station Blackout Rule,10 CFR 50.63. These commitments were l discussed in the Pilgrim station blackout safety evaluation report, dated February 13, 199 l l

2. Alternate AC Power Source and Breaker Alignment The non-Class 1E SBO diesel generator was designed and installed before the SBO rule was 4

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issued by the NRC in 1988. It was initially installed as a part of the safety enhancement program to increase the availability of ac power. The licensee later designated this independent diesel generator to be a station blackout diesel generator (SBO DG) to satisfy j SBO rule requirements. The SBO DG is rated at 2000 kW continuous, 60 hertz, 4160 Vac l at 0.8 power factor. PDC 86-56A covered the site preparation work and PDC 86-56B  ;

covered the installation of the diesel generator, switchgears, bus and associated component !

! This SBO generator is connected between the secondary side of the existing shutdown ;

l transformer and the 4160V safety-related buses A5 and A6. The interface of the SBO DG

! with the shutdown transformer and with buses A5 and A6 is accomplished through a new l non-Class IE,4160V bus A8 as shown in Attachment 2. The two A8 bus breakers enable any one of the available power sources (either from the 23 kV system or SBO diesel generator) to supply 4160V power to vital buses A5 and/or A The team's review included selected design drawings, installation instructions, post-modification test results, procurement specification, breaker protection coordination, 10 CFR 50.59 safety evaluations, SBO voltage drop analysis, cable ampacity, SBO DG load calculation, and the pre-operational tests of the SBO DG conducted in 1988 (TP87-267 and TP88-09).

Based on the revised SBO loading calculation (PS-79, Revision 1), and utilizing the data from the existing distribution system voltage drop calculation, BECo was able to demonstrate that under the SBO conditions, the SBO diesel generator could supply adequate power to the SBO loads of either bus A5 or bus A6 within acceptable voltage conditions. Based on the l review of the these documents, the team determined that the licensee's design packages were l complete and technically sound and that the calculations were acceptable. However, three l

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calculations (SBO diesel generator loading calculation, voltage drop calculation, and short circuit calculation) had not been completed at the time of the inspection. The licensee agreed to formalize the calculations to document the above result . . . - -. . _ _ .

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BECo performed pre-operational tests (TP87-267 and TP88-09) during the March 1988 ,

refueling outage, to demonstrate that the diesel was capable to start, pickup the largest pump motor (RHR) load, and reject 100% rated (2000 kW) load. The SBO DG was loaded for a rated capacity for an hour and peak loaded with 2200 kW for another hour. The team's ,

review of these test results revealed no concerns. The review of the key parameters such as ;

voltage drop, frequency and response time during a large load starting also revealed no i

- concerns. The team considered the pre-cre2tional test to be adequate. The team concluded i that BECo had demonstrated the performance of the SBO diesel and its associated supporting r system !

The team also reviewed the results of several selected quarterly surveillance tests (Procedure No. 8.9.16.1) performed on the SBO diesel and found that the SBO diesel was able to supply the rated power (2000 kW, power factor ranged between 0.8 and 0.9) to 23 kV system  ;

successfully for two hour .4.2 Control Switch and Wiring Modification I The team reviewed Plant Modification PDC 89-043 for the replacement of breaker control I

switches. BECo completed this modification in August 1993. The scope of this modification included the following:

Replaced existing control switches mounted in the control room panel C903 for the ;

residual heat removal (RHR) and core spray pump motors breakers with the similar type switches containing additional contacts and a pull-to-lock (PTL) featur :

, Replaced existing control switches for the two feeder breakers (A501 and A601), !

which isolate the shutdown transformer from emergency buses A5 and A6, with

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similar type switches (General Electric SBM) except that an additional contact and the pull-to-lock feature were added. These switches are located in the control console !

panel C ,

, Added wiring from the replaced switches to the existing annunciators to alarm / monitor the breakers PTL positio . Added four new push-button switches to control panel C3, two for each train, to be used for' manually initiating partial load shed logic to prevent overloading the SBO diesel generato . Modified the plant simulator to reflect the above plant design change !

Based on the review of design documentation, the team determined that the design package

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contained adequate design data and was technically sound. The safety evaluation provided en adequate basis to determine that an unreviewed safety question was not involved with this modification.

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The team also verified by walkdown that all control switches and push buttons installed met Class IE installation requirements including the physical separation of wiring in the control room panel areas. The team noted that two push buttons (per train) were installed in serie both push buttons must be Apressed simultaneously to shed load on panel C3,'similar to the anticipated transient without scram (ATWS) logic to prevent any inadvertent load sheddin The review of the SBO testing revealed that in addition to testing the individual replaced / modified system changes, BECo also performed an overall pre-operational test (TP93-07) to demonstrate that SBO diesel generator was capable of being connected to a safety bus within 10 minutes. The pre-operational test was conducted on May 11, 1993, (refueling outage 9). The test record indicated that the SBO DG was started from the control room C3 panel, and was successfully connected to vital bus A5 in less than 9 minutes. The team concluded that BECo had adequately demonstrated the operability of the modified and replaced equipmen .4.3 Control Logic Modification The SBO DG testing modification (PDC 89-044) was implemented by BECo to meet the criteria of item 3.3.5 of Regulatory Guide 1.155, which specifies that the SBO diesel generator (the AAC power system) must be inspected, maintained, and tested periodically to demonstrate the operability and reliability. This modification also added protective relays (ground protection and directional overcurrent relays) at the 23 kV Rocky Hill Road substation. These relays interface with the primary protection scheme of the Commonwealth Electric Company (CECO) distribution system. The CECO protection scheme requires that any fault condition or significant voltage imbalance on the 23 kV system, during the SBO DG testing mode, must be detected by the circuit protection relays which trip the BECo circuit breaker F15 at the Rocky Hill substation to isolate the BECo portion from the rest of the 23 kV CECO power syste The team reviewed the post-modification test results documented in a copy of test Procedure TP90-14, Revision J. The test was completed by BECo on July 26,1991. The test demonstrated that the protection scheme implemented by this modification functioned properly and in accordance with the design requirement Based on the review of the documentation described above, the team determined that the control logic modification was adequately designed and implemented to satisfy the criteria and RG 1.155 for SBO diesel generator testin . _ _ _ _ _ _ _ _ _ _ _ ____

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2.4.4 Plant Simulator Modification The team toured the plant simulator and verified that the plant simulator had been updated to reflect the above changes, i.e., the breaker alignment feature, the pull-to-lock switch, and push button switches. This modification was part of modification package PDC 89-043 discussed paragraph 2.4.2. The team did not identify any deficiencies in the plaut simulator modificatio .4.5 Documentation Changes The team reviewed sample documentation from each inodification to assure that modification documents had been updated by BECo. The team review included selected samples of control schemes, single line diagrams, relay and protection drawings, FSAR sections, and applicable SBO procedures. All documents were found to be adequately updated to reflect the current plant desig Based on this review, the team concluded that BECo had adequately revised the affected documentation pertaining to the SBO design modification .4.6 Conclusions Based on the review of the modification packages and field verification of the installation, and walkdown of the procedures, the team concluded that: 1) SBO diesel generator and the circuit breakers required for proper alignment were properly installed; 2) post-modification tests were adequately executed; 3) pre-operational tests were conducted in accordance with test procedures and properly demonstrated equipment capability. The team determined that BECo had implemented all SBO modifications for the alternate ac power source identified in the Pilgrim SBO safety evaluation repor .5 Quality Assurance and Maintenance Practices for Station Blackout Equipment The station blackout diesel generator (SBO DG) was installed based upon BECo individual plant evaluation (IPE) considerations prior to NRC issuance of the station blackout rule, 10 CFR 50.63. Subsequently, the licensee designated the SBO DG as an alternate ac (AAC)

power source to energize shutdown safety electrical buses in the event of an SBO. The SBO DG was installed in a configuration that effectively minimized the potential for common mode failure with offsite power or with the onsite emergency DGs. The team reviewed station procedures, maintenance documents, procurement practices, and audits to determine whether proper quality assurance (QA) and maintenance controls were in place to provide reasonable assurance that the SBO DG would be available and function as designed in the event of an SB _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

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2.5.1 Quality Assurance

RG 1.155 provides guidance regarding QA controls appropriate to meet the requirements of

the station blackout rule. Station blackout equipment at Pilgrim is nonsafety-related. Fuel oil and many repair pans for the SBO DG, although nonsafety-related, are procured from the same vendors and to the same standards as material for the safety-related emergency diesel generators. BECo classified SBO equipment as management quality control items (MCQI),

based upon the important role of the SBO DG. As MCQI, all aspects of safety-related,

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10 CFR 50, Appendix B, QA program apply to SBO equipment with the exception of

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procurement document control and the control of purchased material, equipment and services, which are controlled as nonsafety-related commercial purchases. Other systems (e.g., residual heat removal, service water, instrument air, primary containment isolation)

necessary to maintain the capability to cool the reactor core and maintain containment integrity are controlled under the licensee safety-related QA program. This program fully satisfies the guidance of RG 1.155. Quality assurance department audit and surveillance

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documents indicated independent observation over a broad range of SBO related activitie Corrective actions in response to audit findings were promptly implemented.

! The team conducted a walkthrough of the procurement process for nonsafety-related items j using the BECo Inventory Control System User Guide and discussed Procedure 1.7.1, l " Materials Procurement and Stocking Process," and Procedure 1.7.2, " Request for Materials

and Stock Authorizations," with procurement engineering personnel General receipt  !

inspection criteria including purchase order number, physical condition, packaging condition,

and part number were clearly identified and performed. Procurement personnel

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demonstrated proper resolution of receipt discrepancies. However, the team noted that while identification of technical, special inspection, and shelf-life clauses for receipt inspection was clearly delineated for safety-related items, certain procedures did not address identification of these qualification clauses for nonsafety-related items. The component engineering division

, manager stated that although most nonsafety-related items had no applicable receipt

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inspection qualification clauses, procurement specialists were trained to use Attachment 11 of Procedure 1.7.1, when applicable, to identify receipt inspection qualification clauses for nonsafety-related components. The team confirmed this through interviews of procurement

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personnel. BECo acknowledged that this procurement work practice, which relied heavily on training and work experience, did not accurately reflect the written procedures. Problem

report 93.0686 was initiated to revise procurement procedures to accurately reflect work practices. The team concluded that nonsafety-related commercial purchase QA controls for

procurement document control and the control of purchased material, equipment and services satisfied the intent of RG 1.155, paragraph 3.5.

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2.5.2 Maintenance Practices BECo designated the SBO DG and support equipment located within the SBO DG structure as SBO equipment. The team questioned why the A8 electrical bus and related equipment (breaker A801,125 Vdc battery, and cabling) which connect the SBO DG to the safety-related 4 kV buses was not designated SBO equipment and maintained accordingly. Failure of this equipment would make the SBO DG inoperable. BECo stated that the A8 bus and related equipment was tested and maintained in a manner similar to safety-related equipment without being designated as MCQ The team reviewed maintenance and design documents and confirmed the following

< attributes. Procedure 3.M.3-25.8, "A8 Control Power Battery Quarterly Inspection,"

properly validates operability and trends performance of the A8125 Vdc battery. Cabling and associated conduit used during the original SBO DG installation (plant design change 86-56B as discussed in paragmph 2.4.1) was purcetsed as safety-related material. The SBO DG output breaker (A801) and safety-related 4 kV breakers are maintained to the same standards using Procedure 3.M.3-5, " Inspection and Maintenance of 4 kV Breakers." Breaker overhauls are performed by the same vendor to similar standards. Cable connecting the A8 bus to safety-related switchgear is tested similar to safety-related cables using Procedure 3.M.3-4, " Insulation Test." The team determined that preventive maintenance and testing of SBO interfacing components including fuel oil was performed to appropriate standard BECo had not yet established a comprehensive maintenance program for the SBO DG at the time of the inspection (more discussion in paragraph 2.3.2). However, several positive licensee initiatives were implemented to maximize SBO DG availability. Planned system outages (e.g., March 9-10,1993) were effectively scheduled and implemented to group preventive and corrective maintenance activities over a short period of time. The SB > DG system was recently added to the reliability centered maintenance program which is being developed in response to the pending NRC Maintenance Rule. Preventive maintenance recommendations for the SBO DG are similar to those recommended for the station EDG Station blackout equipment has been further designated as a Safety Enhancement Program (SEP) item. Operations and Maintenance controls place strong emphasis on the availability of SEP systems. Procedures 1.2.2, " Administrative Operations Requirements," 1.3.34,

" Conduct of Operations," and 1.5.3, " Maintenance Requests," require dedicated 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> per day repair efforts in the event that the SBO DG becomes inoperable. Additionally, although not required by Technical Specifications, these procedures direct that the reactor be shut down if the SBO DG becomes inoperable for over 30 days. The team reviewed a representative maintenance work package (MR #19303324) for replacement of a faulty SBO DG fuel injector. The work was assigned priority class one, QC hold points were properly established, and the repair was promptly complete I 16  !

2.5.3 Conclusion j The team concluded that proper quality assurance (QA) and maintenance controls were in place to provide reasonable assurance that the SBO DG would be available and function as designed in the event of an SB Generally, BECo has a good maintenance practice for the AAC system, including interface equipment with the SBO DG. However, BECo had not yet established a comprehensive l maintenance program for the SBO D l Procedures to Cope with Station Blackout j 2.6.1 Station Procedures l

The team reviewed station procedures, conducted operator interviews, and performed !

procedure walkdowns to determine whether station procedures provide sufficient operator l

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instruction to cope with a SBO of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> duration and to restore normal long-term core l cooling / decay heat removal after ac restoration. The following procedures were reviewed:

Surveillances  !

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2.1.1 SBO DG Daily Surveillance i 2.1.16 NPRO Tour 3.M.3-2 A8 Control Power Battery Quarterly Inspection 8.C.18 4.16 kV/480V Switchgear Surveillance Systems

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2.2.146 Station Blackout Diesel Generator 2.4.16 Distribution Alignment Electrical System Malfunctions l

Off-Normal Ooerations l

l 5. High Winds (Hurricane)

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5.3.31 Station Blackout Various Alarm Response Procedures (ARP) and Emergency Operating Procedures (EOP)

SBO DG Operations 8.9.16 Manual Start & Load SBO DG 8.9.1 Manual Start & Load SBO DG via the Shutdown Transformer l

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Severe weather and off-normal SBO procedures provide excellent instruction to operators regarding SBO response and immediate ac power restoration. In SBO Final Rule information submittal, dated April 17, 1989, BECo took one exception to the severe weather procedure guidance provided in NUMARC 87-00. Procedure 5.2.2 provides instruction to reduce reactor power to within turbine load reject capabilities (130 MWe) prior to winds onsite reaching hurricane velocity, but does not specify a reactor shutdown as recommended in NUMARC 87-00. This action reduces the probability of an automatic reactor trip while ;

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preserving the availability of electrical power to the reactor plant via the unit auxiliary transformer in the event the hurricane disrupts offsite power. The NRC safety evaluation of f the Pilgrim SBO submittal, dated February 13,1991, did not take exception to the planned reactor power reduction in lieu of a reactor shutdown and concluded that the licensee method i

l of dealing with an SBO was acceptable. The team confirmed that Procedure 5.2.2 provides l appropriate instruction for turbine load reduction and other precautionary operator actions.

! Site preparations for severe weather are clearly specified and have been properly

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demonstrated during periods cii:igh winds over the past two year Procedure 5.3.31 clearly identifies the % p1oritized objectives of (1) plant stabilization i following the scram, (2) restoration of ac power, and (3) load shedding to conserve station l batteries and directs operators to supporting procedures'as necessary. The importance of the high pressure coolant injection and reactor core isolation cooling systems for reactor vessel level and pressure control is emphasized. Specific distribution breaker interlocks and load l transfer concerns for starting and loading the SBO DG are highlighted in caution statements to the operators in Procedure 2.2.146. Emergency operating procedures direct operators to take appropriate action to mitigate loss of ventilation effects, prioritize backup sources of makeup water, and preservation of containment integrity. The team independently reviewed security system access controls and confirmed that operators would have access to necessary locations within the protected area to implement SBO procedures. A dedicated diesel generator and uninterruptible battery power supply provide sufficient security system power to permit normal doorway access for operators to carry out required actions during a SB Subsequent restoration of ac power from offsite sources is performed using Procedure 2.4.1 The team noted that some portions of Procedures 2.2.146,2.4.16, and 5.3.31 were not worded clearly. Examples included direction to an incorrect procedure number for restoration of offsite ac power sources and unnecessary complexity for restoration of offsite ac power. Specific examples were discussed with the Chief Operating Engineer who initiated action to improve clarity and reduce the amount of time needed to restore ac power. Routine surveillance procedures and periodicity were properly established to provide reasonable assurance that SBO DG will operate properly if called upon.

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2.6.2 Conclusion The team concluded the station procedures provided appropriate instruction for operators to respond to a SBO event. Minor procedure discrepancies were discussed with operations management personnel who promptly initiated corrective action to improve clarity and reduce the amount of time needed to restore ac power. Routine surveillance procedures and periodicity were properly establishe .7 Station Blackout Training Training and personnel staffing must be adequate to ensure operators can cope with a SBO of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> duration and restore normal long-term core cooling / decay heat removal after ac power restoration. The team reviewed training documentation, interviewed operators, and performed a walkthrough of selected SBO procedur-; on the control room simulator to assess the effectiveness of SBO trainin Station blackout training was conducted during pduc industry events training sessions which each operating crew attends at six-week interv.ls and during biannual SBO DG, emergency DG, and 4160 Vac system training. All licensed operators attended SBO training sessions following refueling outage No. 9 which discussed the implementation of the 10 minute SBO DG start design change. Lesson plans and simulator scenarios were of high quality and all operators satisfactorily demonstrated their knowledge on written tests or simulator performance. Operator knowledge of SBO implementing procedures and EOPs for long-term decay heat removal was a noted strength during interviews and simulator demonstrations. Operators demonstrated the capability to stabilize the reactor plant and energize a safety shutdown bus from the SBO DG within 10 minutes of SBO event initiatio Training department personnel were knowledgeable and upgraded lesson plans to reflect the most recent SBO DG design changes and related industry events such as the August 1992 hurricane at Turkey Poin The team concluded that operators were effectively trained and staffing levels were appropriate to cope with a SB .8 Alternate AC Source Interface with 23 kV System The team reviewed the electrical system of Pilgrim station to determine the role of the 23 kV transmission line and the shutdown transformer as shown in Attachment 2. The operation of Pilgrim electrical system is as follows:

During normal plant operation, emergency buses A5 and A6 are powered by the main generator via the unit auxiliary transformer (UAT). When the unit trips, the power supplies to buses A5 and A6 are fast-transferred to the 345 kV switchyard and the startup transformer (SUT). If this offsite source is not available, buses A5 and A6 will be powered by the respective emergency diesel generators (EDGs) (EDG 1 to A5 and EDG 2 to A6) within

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10 seconds. If the EDGs become unavailable, A5 or A6 (or both) will be automatically connected to the 23 kV line via the shutdown transformer within 12 seconds. If the 23 kV line is lost, the station blackout diesel generator is manually started to power either A5 or A6 (not both). The degraded voltage relays used to protect A5 or At re located on the secondary side c.f the SUT, upstream of the feeder breakers. Wl" A5 or A6 is being powered by the 23 kV source, no protection is available to proter .5 or A6 against degraded voltage condition. The team raised the concern that the vital motors connected to A5 or A6 could be damaged before the SBO condition is declared. In response to the team's concern, BECo provided the team with preliminary assessment datajust before the exit meeting. These data indicated that historically, the voltage at the 23 kV line varied between 22.0 kV and 23.5 kV, and that based on the existing plant voltage drop calculation, the vital load connected to A5 or A6 had sufficient voltage for operation. The team agreed that there was no immediate concern. However, degraded voltage condition can still occur at the 23 kV source. BECo agreed to evaluate this issue and to determine proper resolution. This item is unresolved pending NRC review of BECo resolution (50-293/93-80-03). .

I BECo indicated that they met General Design Criteria (GDC) 17 with the use of two 345 kV transmission lines. However, it was noted that Technical Specifications Section 3.9.A. allowed the reactor to be made critical and operate (without exceeding a limiting condition for operation and entering an action statement) with only one 345 kV transmission line and the 23 kV line powering the shutdown transformer. It was not clear which two sources are used for meeting GDC 17 requirements. BECo was unable to provide analytical documents to substantiate the quality of the 23 kV line for GDC 17 application (e.g., degraded voltage protection, capacity calculations, etc.) BECo agreed to evahate this issue. This item is unresolved pending NRC review of BECo's evaluation and/or corrective actions (50-293/93-80-04). UNRESOLVED ITEMS Unresolved items are matters about which more information is required in order to ascertain whether they are acceptable items, deviations or violations. Unresolved items are identified in the Executive Summary of this repor .0 EXIT MEETING BECo management was informed of the scope and purpose of this inspection at the entrance meeting on October 18, 1993. The findings of this inspection were discussed with the BECo representatives during the course of the inspection and presented to BECo management during the exit meeting on October 22,1993. BECo did not dispute the inspection findings during the exit meeting. In addition, the status of the inspection findings was discussed with BECo's representative during a subsequent telephone conversation on December 10, 199 A list of attendees is presented in Attachment _ _ -

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l A'ITACHMENT 1 )

PERSONS CONTACTED Boston Edison Company J. Calfer Senior Compliance Engineer B. Chanard Power System Division Manager W. Clancy M&CES Manager S. Das Senior Electrical Engineer

• N. Desmond Compliance Division Manager R. Gay Senior Compliance Engineer P. Hamilton Licensing Division Manager K. Kee Senior System Engineer

• E. Kraft, J Vice President, Nuclear Operation W. Imbo Senior Licensing Engineer D. Long Senior Systems and Safety Analysis Engineer

• V. Oheim Regulatory Affairs and EP Manager

• M. Perito Nuclear Watch Engineer W. Robert General Manager, Technical L. Schmeling Plant Manager D. Sitkowski Senior Electrical Engineer T. Venkataran Manager, Surveillance Division M. Williams Senior QA Engineer U.S. Nuclear Regulatory Commission A. Cerne Resident Inspector J. Durr Chief, Engineering Branch, DRS J. Macdonald Senior Resident Engineer All personnel except those marked (*) attended the exit meeting on October 22,1993.

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l 23KV ftFCONDARY)

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- E SWITCHYARD Shutdown E (PREFERRED)

Transformer E ww f)G000KW) Main l mm Transformer 23/4.16KV ww Unit Auxilia T Startup g [] Transfonner 5/23KV Transformer i

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poh 4.16KV m" "* b ED 2 23/4.16KV 345/4.16KV gggy g ,gy g

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a aab Y baa A6 a l

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A5 Ma.in Class IE 4.16KV Generator Class IE 4.16KV \

{} Bus , Bus O

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.4 W 4.16KV/480V 4.16KV/480V O a B2 B1 -

480V 480V ATTACHMENT 2 ALTERNATE AC (A AC) CONFIGURATION NON CLASS 1E DIESEL GENER ATOR

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