ML20205Q800

Safety Evaluation Supporting Amends 205 & 235 to Licenses DPR-71 & DPR-62,respectively

ML20205Q800
Person / Time
Site:	Brunswick
Issue date:	04/15/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20205Q788	List: ML20205Q783 ML20205Q800
References
NUDOCS 9904220072
Download: ML20205Q800 (15)

Text

9 fcoq p$ _

t UNITED STATES g,

.j NUCLEAR REGULATORY COMMISSION it WASHINGTON, D.C. 2055% 0001 o

g SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 205 TO FACILITY OPERATING LICENSE NO. DPR-71 AND AMENDMENT NO. 235 TO FACILITY OPERATING LICENSE NO. DPR-62 CAROLINA POWER & LIGHT COMPANY BRUNSWICK STEAM ELECTRIC PLANT. UNITS 1 AND 2 DOCKET NOS. 50-325 AND 50-324

1.0 INTRODUCTION

On November 1,1996, Carolina Power & Light Company (the licensee) submitted a license amendment request for the conversion of the current Technical Specifications (TS) to the Improved Technical Specifications (ITS) for the Brunswick Steam Electric Plant (Brunswick),

Units 1 and 2. That request included, as a "beyond scope change, an extension of the Allowed Outage Time (AOT) for certain electrical buses. The proposed change would only be applicable when one unit is shutdown and the other unit is at power. The purpose of that change was to allow additional time for performance of preventive maintenance on buses, transformers, breakers, and other related electrical equipment in the shutdown unit. In order to support the ITS issuance schedule, that "beyond scope change," which adds a new Condition B in ITS 3.8.1, "AC Sources - Operating and a new Condition A in ITS 3.8.7, " Distribution Systems -

Operating," had to be removed from the scope of the ITS conversion.

By letter dated May 22,1998, as supplemented by letters dated September 14,1998, January 4,1999 and March 19,1999, the licensee requested continued review of the bus AOT extension and provided supporting information. The proposed change would allow one division of the 4.16 kV balance-of-plant (BOP) and emergency buses of a shutdown unit to be out of service for up to 7 days for planned bus maintenance. Currently the TS requirements for the i

operating unit are restrictive in only allowing 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for the 4.16 kV BOP buses and 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for emergency buses on a shutdown unit to be out of service, which does not provide adequate time to perform the planned maintenance. The effect of the proposed AOT extension is to i

permit operating one unit at power for up to 7 days while the licensee performs the planned maintenance on the shutdown unit.

Since the licensee's original TS amendment submittal on November 1,1996, the licensee has submitted several supplemental letters, including a [[letter::BSEP-99-0042, Provides Response to RAI Re Itss,As Contained in Rev 1 of NUREG-1433, Std Tech Specs General Electric Plants,BWR/4, Proposing Lengthening AOTs for Balance of Plant & Emergency Electrical Buses to 7 Days|letter dated March 19,1999]], in response to I

the staff's request for additionalinformation. The supplementalletters contained clarifying information and did not change the initial no significant hazards consideration determination or the scope of the original Federa/ Register notice.

9904220072 990415 PDR ADOCK 05000324 p

PDR

4 2

2.0 EVALUATION i

2.1 Background

Since current design of the onsite electrical power distribution system at most nuclear units is based on the concept of independent and redundant load groups between the units, there is no TS restriction on the operating unit that also applies to the shutdown unit. To maintain a high

)

level of reliability, the maintenance of the electrical power distribution components is required at regular intervals and is performed when the unit is shut down or during a refueling outage.

However, the design of the electrical power distribution system for the Brunswick is unique in that it shares four divisions of 4.16 kV emergency bus load groups (i.e., E1, E2, E3, and E4) between two nuclear units. Each emergency bus has its associated dedicated emergency diesel generator (EDG) and is also connected by a single circuit to a 4.16 kV BOP bus that is connectable to two offsite power sources. The E1 and E2 load groups are supplied from 4.16 kV BOP buses 1D and 1C respectively, and primarily serve Unit 1 loads, while the E3 and E4 are supplied from 4.16 kV BOP buses 2D and 2C respectively, and primarily serve Unit 2 loads.

Because of this shared electrical power distribution system design, some engineered safety feature (ESF) loads (for example, pumps and valves in systems such as residual heat removal (RHR) and sarvice water) associated with an operating unit would be supplied from a unit that is shut down. Therefore, the TS requirement for an operating unit requires all four emergency buses to be operable whenever either unit is operating (i.e., Mode 1,2, or 3). Thus, a 4.16 kV BOP and its emergency buses associated with a shutdown unit could not be removed from service longer than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> without affecting safety equipment in the operating unit that is credited for mitigating the consequences of a design-basis event.

The licensee is requesting extended outage time to perform certain maintenance and testing of electrical equipment in the shutdown unit. The licensee states that the planned maintenance consists of preventive maintenance and surveillance testing and it will be performed on one division of the shutdown unit, which includes (1) the 4.16 kV BOP bus, (2) the single circuit path connecting the 4.16 kV emergency bus from the 4.16 kV BOP bus, (3) the EDG, and (4) its associated load group, which includes the 4.16 kV emergency bus and its downstream components (i.e.,480 V and 120 V vital buses, breakers, transformers and interconnecting cables).

The licensee has proposed to add Condition B in ITS 3.8.1 and Condition A in ITS 3.8.7 and to modify the Bases B.1 section for Brunswick, Units 1 and 2. These proposed ITS Conditions and the staff evaluation for these Conditions are provided below:

3 Addition of Condition B of ITS 3.8.1 for Brunswick Unit 1 i

CONDITION REQUIRED ACTION COMPLETION TIME

~.

Notes

1. Only applicable when Unit 2 (1) is in Mode 4 or 5.

2. Condition B shall not be entered in conjunction with Condition A.

B. Two Unit 2 (1) offr.ite B.1 Declare required immediately irom discovery circuits inoperable feature (s) with no of Condition B concurrent due to one Unit 2 (1) power available with inoperability of balance of plant inoperab!e when the redundant required feature (s)

]

circuit path to the redundant required downstream 4.16 kV feature (s) are emergency bus inoperable.

inoperable for planned maintenance.

AND AND 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> DG associated with the B.2 Perform SR 3.8.1.1 for affected downstream OPERABLE offsite AND 4.16 kV emergency circuit (s) bus inoperable for Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter planned maintenance.

AND 7 days B.3 Restore both Unit 2 (1)

AND offsite circuit and DG to OPERABLE status 10 days from discovery of failure to meet LCO 3.8.1.a or b Note: Numbers shown inside parentheses are applicable for Brunswick Unit 2 ITS.

l 1

l

l A

Addition of Condition A of ITS 3.8.7 for Brunswick Unit 1 i

l CONDITION REQUIRED ACTION COMPLETION TIME l

l A. One AC electncal power A.1 Restore affected load 7 days distribution subsystem group bus (e to l

inoperable for planned OPERABLE status.

AND l

maintenance due to j

either inoperable load 176 hours0.00204 days <br />0.0489 hours <br />2.910053e-4 weeks <br />6.6968e-5 months <br /> from discovery of i

group E3(1) bus (es) or failure to meet the LCO l

inoperable load group E4(2) bus (es)

Note: Numbers shown inside parentheses are applicable for Drunswick Unit 2 ITS.

l The licensee states that the vendor recommends major preventive maintenance on the electrical buses at 6-year intervals, and the maintenance rule,10 CFR 50.65, " Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," requires monitoring of the reliability and availability of the electrical distribution system so that their performance limits i

are not exceeded. If the reliability or availability dues not meet its performance limits, Section (a)(1) of the maintenance rule would require increased management attention to restore performance. With the shared electrical system design at Brunswick, the licensee finds that the TS requirement for the operating unit requires all four emergency buses to be operable whenever either unit is operating. With the current 24-hour (TS 3.8.1) and 8-hour (TS 3.8.7)

AOTs, it does not provide adequate time to perform the planned electrical bus maintenance associated with the shutdown unit. Therefore, to perform the planned maintenance on the electrical buses to ensure that the established performance limits are not exceeded, a dual unit outage or a longer AOT is required. Since no dual unit outages have been planned for the future at Brunswick, the licensee proposed that the AOT to be c@nded for up to 7 days to provide adequate time in which to perform this planned maintenance.

Also, to minirnize equipment unavailability (i.e., to avoid repeated entries in ITS 3.8.1 and ITS 3.8.7) and to minimize the complexity of the planning and scope outages, the licensee stated in its ITS submittal that it is highly desirable to service one division of electrical buses during a single outage window (i.e., work sequentially). The licensee estimates a minimum of 3 days would be required to perform the above-mentioned full scope of work. The licensee further states that this estimate is consistent with its administrative time limit for taking equipment out of service, which is half of the associated AOT.

The staff reviewed the design of the current electrical distribution system at Brunswick and the licensee's responses to the staff's request for additional information and provided the following deterministic and risk assessment of the proposed 7-day AOT extension for ITS 3.8.1 and 3.8.7 for Brunswick, Units 1 and 2.

2.2 Deterministic Evaluation.

(1)

Operation with only three ac electrical distribution system load groups is already enveloped by the existing accident analysis, which considers a loss-of-coolant accident

1 l

r3

/ loss of offsite power (LOCA/ LOOP) on one unit and a safe shutdown of the other unit concurrent with the worst-case single failure. Since the planned maintenance will be performed while one unit is shut down, the three electrical distribution load groups are adequate to mitigate the design-basis accident for the operating unit.

(2)

The licensee reviewed all the ESF loads (associated with the operating unit) that are supplied from the shutdown unit's emergency power system load group and found most of them to have a 7-day AOT, except three loads where 480 V and 120/208 vital buses have an 8-hour AOT and an incoming feeder to a 4.16 kV emergency bus has a 24-hour AOT. Thus, the proposed 7-day AOT for the inoperable BOP and emergency buses would be consistent with the current 7-day AOT associated with the equipment they support for the operating unit.

(3)

Required Action B.1 of the proposed ITS 3.8.1 will require monitoring of the OPERABILITY of the redundant required features. Immediately upon discovery of an inoperable redundant required feature, the supported ITS Actions must be entered in accordance with limiting condition of operation (LCO) 3.0.6. This step will ensure that appropriate remedial actions are performed for any additional inoperability.

Outage planning will ensure the operability of required redundant TS equipment on the three load groups of the ac electrical power distribution system before removing one load group associated with the shutdown unit from service. The TS will further restrict plant operation with a plant configuration that could increase overall plant risk. If any BOP bus associated with any other Unit 1 or Unit 2 emergency power system load group is lost (e.g., loss of BOP bus or no offsite power) concurrent with the planned BOP bus outage, the operating unit, per Condition I of TS 3.8.1 and Condition F of TS 3.8.7, must enter LCO 3.0.3 (requiring shutdown).

-(5)

In order to prevent an adverse impact on the shutdown unit, extensive planning and reviews by Brunswick Safe Shutdown Risk Management personnel and the requirements of ITS 3.8.2, "AC Sources - Shutdown" and ITS 3.8.8, " Distribution Systems - Shutdown" l

will ensure that the ac sources necessary to support the operability of the required equipment are maintained for the shutdown unit and the Outage Risk Analysis and Management model would be used to evaluate the level of defense in-depth associated l

with the shutdown unit.

(6)

In order to ensure that any concurrent inoperabilities that result in a loss of safety function do not exist, the Safety Functional Determination Program (SFDP) was added. This SFDP program requires provisions for cross-division checks to ensure that a toss of the capability to perform a safety function assumed in the accident analysis does not go undetected. In addition, training on the SFDP was also provided to alllicensed operations personnel before implementation of the proposed ITS.

(7)

The on-line scheduling procedure, OAP-025, "BNP Integrated Scheduling," provides guidance for evaluating the risk of taking equipment out of service and the actions to take if an unforeseen component failure or a changs in plant conditions would affect plant risk.

Planned maintenance (i.e., preventive mainter'nce and surveillance testing) activities are i

evaluated in aovern of the work week using the Probability Safety Assessment (PSA)

1 i

6 model. Thus, OAP-025 would address work control practices of the operating unit for the proposed planned maintenance activity at Brunswick.

1 (8)

Additionally, procedure OAP-025, attachment 4, " Methodology For Assessing And i

Managing Plant Risk," Step 8 contains specific steps and actions to be taken for the I

operating unit when removing a 4.16 kV emergency bus from service. No high risk evolutions or system outages (including high risk surveillance tests) on the operating unit will be planned to be performed concurrent with a 4.16 kV emergency outage, unless a.

approved by the plant general manager with risk information being considered.

(9)

Per recommendation of Regulatory Guide 1.177, the licensee will incorporate a configuration risk management program (CRMP), which ensures that risk-significant configurations would not be entered for planned maintenance activities and appropriate actions would be taken if unforeseen events place the plant in a risk-significant configuration. CRMP will be added in section 5.5.13 of the technical requirements j

manual (TRM), which will be incorporated by reference into the Updated Final Safety i

Analysis Report, and changes to the TRM will be subjected to the requirements of J

10 CFR 50.59.

The current TS for the operating unit does not provide sufficient time to perform the manufacturer's recommended 6 yearly preventive maintenance activities for the electrical distribution system equipment for the shutdown unit. Therefore, the staff agrees that the proposed 7-day AOT extension would provide a sufficient time in which to perform the preventive maintenance activities to maintain a high level of reliability of the electrical power distribution system.

Based on the staff review of the existing accident analysis and TS, and additional measures (that is, procedures, programs, planning and training), the staff finds that the licensee's actions provide reasonable assurance that plant safety will continue to be maintained during the removal of the BOP and emergency buses from service for up to 7 days. Additionally, the staff finds that the proposed AOTs are within the bounds of the current design basis of the plant and the additional measures provide reasonable assurance that risk-significant equipment outage configurations will not occur when the BOP and emergency buses are removed from serv :s for 7 days. The risk aspects of this TS amendment are evaluated further below. The staff concludes that the proposed 7-day AOT extension for ITS 3.8.1, Condition B, and ITS 3.8.7, Condition A, from the current 24-hour and 8-hour AOTs is acceptable.

2.3 Risk Evaluation This evaluation is based upca the guidance and three-tiered approach outlined in Regulatory Guides (RGs) 1.174, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," and 1.177, "An Approach for Plant-Specific, Risk-Informed Decision Making: Technicci Specifications."

1

)

I 7

I Tier 1: PSA Capability and Insiahts PSA Model Ouality The Brunswick Level 1 Probabilistic Safety Assessment (PSA) model was last updated in 1996 to reflect the changes to the plant since the 1992 IPE submittal. The updated model reflects new procedures, plant modifications, plant-specific component performance data, and initiating event l

frequencies. The staff notes that the licensee has procedural requirements for periodic updates i

of the PSA model. The Brunswick PSA model updates and analyses receive an internal peer review and a supervisor's review. An upgrade and Update of the Inodelis underway at present l

and is scheduled for completion in 1999. Also, the staff believes that the insights gained from the Brunswick PSA model are reasonable. Thus, given these considerations, the staff finds that the Brunswick PSA model is of reasonable quality to be used in assessing the risk from internal events associated with this TS amendment.

Risk Insiohts The risk that is associated with configurations allowed by the TS amendment is predominately l

related to loss of decay heat removal following an initiating event. Decay heat removal at Brunswick is accomplished, following an initiating event, either by use of the condenser, suppression pool cooling, or containment venting. The maintenance at the shutdown unit results, in part, in removing AC power to a valve (which is in the closed position) on one RHR train l

needed for suppression pool cooling at the operating unit. It also removes AC power to the same RHR train Low Pressure Coolant Injection (LPCI) mode injection valves (which will be closed).

Some initiating events can result in loss of the condenser as a heat sink due to closure of the Main Steamline Isolation Valves (MSIVs), which may result in steam dump to the suppression pool. The initiating events contributing most to the risk are LOOP and MSIV closure transients.

Suppression pool cooling would be available from the operable RHR train. Should suppression pool cooling become unavailable and non-recoverable following a loss of the condenser, containment venting would be relied upon to remove decay heat. Loss of all decay heat removal means would result in core damage.

Given the importance of decay heat removal for this TS amendment, the staff reviewed the keensee's processes to protect and recover the various decay heat removal means dunng the l

maintenance. This included prevention of wrong-train maintenance, recovery of the maintenance-affected RHR train, protection of the containment venting function, and protection rf the remaining electrical cross-tie betweep units.

The staff noted that the large number of planned activities introduce a greater likelihood of plant personnel performing wrong-train maintenance; therefore, proper maintenance controls during the evolution are important. Wrong-train maintenance could affect safety-related equipment at both units and possibly cause a transient. The licensee has a number of controls in place. Plant procedures OPLP-21, " Independent Verification," and OPS-NGGC-1301, " Equipment Clearance" require independent verification of all clearances and two individuals present when racking out breakers or when working on energized equipment. This practice is very important in minimizing risk, especially when performing a large number of activities over a prolonged time period. In addition, the emergency buses and substations are labeled and color-coded. Also, physical barriers are set up to keep personnel out of the incorrect Loit switchgear rooms. Furthermore, in i

8 order to prevent human errors, the licensee will conduct a number of briefings prior to performing the maintenance and will provide supervisory oversight. The staff finds that these practices substantially reduce the potential risk to both units from wrong-train maintenance during the evolution.

The licensee indicated that equipment impacted by the proposed work could be restored in less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. However, for some initiating events (for example, LOOP) at the operating unit, suporession pool bulk temperature could reach 200 F within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of loss of suppression pool cochng. This is the TS temperature cited in the staff's evaluation of the Brunswick station blackout (SBO) analysis. The Updated Final Safety Analysis Report (UFSAR), though, has been updated to indicate that the design temperature of the suppression poolis 220*F. If the operable RHR train fails during an event, there is a possibility that the maintenance-affected RHR suppression pool cooling valve may not have AC power restored prior to the suppression pool reaching its design temperature. The risk from this aspect of the maintenance is substantially decreased due to operator actions to manually open the valve and place the RHR loop into suppression pool cooling service. The licensee indicated actions to accomplish this would take approximately one-half hour. Guidance to manually place the maintenance-affected RHR loop into suppression cool cooling service is found in procedures 1(2)OP-17, " Residual Heat Removal System Operating Procedure," OEOP-01 UG, " Users Guide," as well as OAOP-36.1, " Loss Of Any 4160V Buses Or 480V E-Buses." Thus, the staff finds that the licensee has the ability to recover the maintenance-affected RHR loop and to use it to provide suppression pool cooling before the suppression pool temperature reaches its design limit.

Containment venting would be needed if the RHR system cannot provide suppression pool cooling. The staff notes that the containment venting function at the operating unit is not affected by the maintenance at the shutdown unit. Also, scheduled maintenance at the operating unit, which may affect the containment venting function, would be planned in accordance with the licensee's Tier 2 process, which would not allow high safety significant systems to be out-of-service during the AC divisional work at the shutdown unit.

Due to the maintenance which de-energizes one division of AC power at the shutdown unit, electrical cross-ties to and from the out-of-service e;nergency bus at the shutdown unit will not be immediately available. The cross-tie breakers for the remainino shutdown unit emergency bus and the operating unit's emergency buses will be available per procedure 00P-50.1, " Diesel Generator Emergeng Power System Operating Procedure." Activities and maintenance specific to the remaining division cross-tie breakers would not be allowed per procedure OAP-025, "BNP INTEGRATED SCHEDULING." Thus, the licensee will maintain the ability to establish an electrical cross-tie between the units' emergency buses.

As noted above, an RHR valve needed for suppression pool cooling and the same RHR train LPCI mode injection valves at the operating unit will be de-energized and closed. In addition, the recirculation pump discharge and discharge bypass valves on the associated recirculation 1000 (which receives a close demand on a LPCI signal) will be de-energized and open. The staff's review noted that an open recirculation loop is an analyzed condition for the licensing / design basis LOCA events. Tha licensee's design basis LOCA SAFER /GESTR analysis found that for j

recirculation loop breaks, any two low pressure injection pumps will provide adequate makeup.

During the maintenance, the two Core Spray (CS) system pumps and two RHR pumps will be available at the operating unit. Thus, sufficient low pressure system makeup will be available for i

}

I i

1

]

I 9

a design basis LOCA during the maintenance evolution. In the event that a system redundant to i

LPCI becomes inoperable (for example, CS pump), the staff notes that TS 5.5.11, " Safety Function Determination Program (SFDP)" would require a unit shutdown. The staff a!so notes that, based on the licensee's PSA model, LOCA initiators are not dominant core damage 4

frequency (CDF) contributors for this TS amendment.

The licensee performed a screening fire PSA analysis which indicated that, in 19 bounding case, the annual average CDF increase for the operating unit from fires could be substantial (approximately 1E-5/yr per out-of-service AC division at the shutdown unit). The analysis considered the cumulative risk from fires in different areas which could affect safety-related equipment. Given the potential vulnerability to fires during the maintenance, the licensee committed to provide explicit procedural guidance in OAP-025. This guidance states that the risk impact of ignition sources, such as grinding and welding, in the operating unit will be reviewed and appropriate measures implemented. These measures are discussed in the staffs Tier 2 assessment.

High winds can cause a LOOP at one or both units. The Brunswick Individual Plant Examination of External Events (IPEEE) identified high winds, which occur with a greater frequency than hurricanes or tornadoes, as the most limiting weather event. During the maintenance evolution, there will be three of four diesel generators operable at the site. As modeled in the PSA model, one diesel generator at each unit provides enough power to shut down its respective unit. If SBO occurs at either unit, an inter-unit electrical crosstie would be available. Also, the High Pressure Coolant injection and Reactor Core Isolation Cooling systems (at the operating unit) would be available since the licensee does not plan outages on the high pressure injection systems concurrent with a 4160 V emergency bus / diesel generator outage. The annual average CDF increase due to high winds was shown to be small.

Since the scope of the planned maintenance has not been possible due to the current length of the AOTs in the existing TS, corresponding maintenance unavailability criteria were not developed. In support of this TS amendment, the licensee developed Maintenance Rule (MR) unavailability performance criteria for the BOP and emergency buses. These are: 1) 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br /> during shutdown and 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> online in a 3 year period for each of the emergency buses, and

2) 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> during shutdown and 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> online in a 3-year perind for each of the BOP buses.

In the PSA model, the licensee assumed an unavailability of 7 days per year for each bus (at the shutdown unit), which bounds the MR unavailability performance criteria. For each of the diesel generators, the performance criteria is 867 hours0.01 days <br />0.241 hours <br />0.00143 weeks <br />3.298935e-4 months <br /> in a 3-year period. In the PSA model, the diesel generator unavailability is assumed to be 14 days per year (at the shutdown unit), and bounds the MR unavailabilty performance criteria. The licensee estimated that the BOP and emergency buses' unavailabilities increased the internal events CDF by 1.4E-6/yr over the baseline internal events CDF of 9.2E-6/yr.

1 The Brunswick units have a Mark-l containment. The baseline Large Early Releas

.equency (LERF) for the Brunswick units was reported to be 2.46E-6/yr. The LERF is influe',,d by the potential for loss of suppression pool cooling during the bus maintenance at the sbdown unit.

The licensee noted that, in the case of loss of RHR without anticipated transient without scram, loss of suppression pool cooling cases in the IPE (that is, Case IAe1) would not result in a large early release. It is possible, however, that steam blowdown, following vessel failure, could challenge primary containment seals. The licensee estimated an incrementa! large early release

t 10

)

probability of SE-8, assuming the maintenance configuration occurs for 7 days per year (that is, l

an annual average LERF increase of SE-8/yr).

l l

The staff also reviewed the impact of the work on the shutdown unit. In the configurationt allowed by the TS amendment, one division of AC power at the shutdown unit would be inoperable. During this period, AC power would be removed to the inboard shutdown cooling suction isolation valve for certain AC divisions. In the event of a shutdown cooling isolation signal, the DC-powered outboard shutdown cooling suction isolation valve would be required to close. The staff's review noted that none of the planned work would affect the ability of the DC-powered isolation valve to close. Isolation signals could be generated on high reactor pressure or low level. A high reactor pressure isolation signal would be sent to the shutdown cooling suction isolation valves. A low level isolation signal would be sent to the shutdown cooling suction isolation valves and to the LPCI inboard injection isolation valves when the RHR system is in the shutdown cooling mode. Since the LPCI injection valves are powered from the opposite (operating) unit, these valves at the unit in shutdown cooling would have power to isolate. In the event of loss of shutdown cooling isolation, the licensee uses procedure 001-01.02, " Shift Routines And Operating Practices" and OEOP-01-UG, " User's Guide." Thus, the isolation capability remains, although redundancy may be nduced for shutdown cooling isolation, and the licensee has procedures to cope with loss of isolation capability.

The following pumps will be available for inventory makeup capability at the shutdown unit during the AC division maintenance: one CS pump, one RHR pump from the maintenance-affected loop, the RHR loop providing shutdown cooling after re-alignment from the shutdown cooling mode, one Control Rod Drive system pump, and the Condensate System. In addition to these systems, alternate cooling injection alignments are available in the Emergency Operating Procedures. The staff believes it is important to keep these injection sources available at the shutdown unit during the AC divisional work to minimize risk from loss of reactor coolant inventory events.

The requirements of ITS 3.8.2, "AC Sources-Shutdown" and ITS 3.8.8, " Distribution Systems -

l Shutdown" will ensure that AC sources necessary to support the operability of required equipment are maintained for the shutdown unit during the maintenance evolution. Also, as previously noted, the electrical cross-tie between unit emergency buses will be available.

l Thus, for this TS amendment, the staff's Tier 1 review finds that the risk associated with this TS l

amendment is small.

Tier 2: Avoidance of Risk-Sianificant Confiourations l

The licensee's procedure OAP-025, "BNP INTEGRATED SCHEDULING," Revision 6, addresses on-line maintenance configuration control. The OAP-025 methodology for assessing and managing on-line maintenance plant risk is detailed and incorporates PSA insights for dominant accident type such as Loss of Decay Heat Removal. OAP-025 provides guidance to use the Equipment Out Of Service (EOOS) PSA tool and/or to consult the PSA group for planning work, as well as for assessing the risk of emergent failures or changing plant conditions. The licensee informed the staff that the EOOS toolis used to calculate the risk for PSA components, regardless of whether the components have been classified as low or high safety significant.

t The systems of high safety significance have been identified based on the 1996 PSA model insights and/or as determined by the Expert Panel. The EOOS analysis generates a predictise

11 risk profile which is roviewed by the work management team and is incorporated into the work planning process.

OAP-025 contains specific steps and actions for the operating unit to take when removing a l

4160V emergency bus from service. No high risk evolutions or system outages on the operating unit will be planned to be performed concurrent with a 4160V emergency bus outage. This includes high risk surveillance tests. Should unforeseen events occur which would require concurrent outages on a 4160V emergency bus and another high safety significant system, continued operation of the operating urit requires approval by the Plant General Manager with risk information being considered in the decision. In such cases, the basis for continued operation will be documented. Also, as noted in the staff's Tier 1 review, the initiating events which are importan+ to the operating unit during the AC division work at the shutdown unit are LOOP and MSIV closure transients. OAP-025 provides guidance to consider accident types such as loss of decay heat removal, SBO, and plant transients at high pressure when scheduling work.

l Also, as noted previously, the licensee will add guidance to OAP-025 to evaluate the risk impact of ignition sources in the operating unit and to take appropriate compensatory measures, in the j

event of an emergent item occurring on the operating unit which requires any welding, grinding, l

or hot work, the following compensatory measures would take place. The operating unit would complete required permits and determine the impact this emergent work would have on the AOT U tne 4160V bus outage, as well as any other outage evolution that might increase risk. If the licensee identifies that the impact is unacceptably high, the task would be postponed until the 4160V bus is returned to service. Should hot work repair on the operating unit be required while the 4160V bus is out of service, conservative actions such as increased supervision, simulation of the required repairs at the technical training center, and ensuring that the most qualified personnel will perform the task will be taken. Additional procedurally required actions which will take place include establishing fire watches and placing fire retardant blankets in place around the hot work area. Thus, the staff finds that the licensee has clearly identified appropriate compensatory measures to address the staff's concern of the risk from fires to the operating unit during the maintenance evolution.

Significant weather conditions, such as the approach of a hurricane, are also factored into the licensee's work planning process. OAP-025 provides guidance to delay scheduled system outages which have not started until plant conditions are favorable. Also, procedure OAP-13.0, Revision 22, " Operation During Hurricane, Flood Conditions, Tornado, or Earthquake" provides guidance, in the event of a hurricane approach, to expedite the recovery of all safety equipment that may be in an LCO, especially equipment needed for LOOP.

Furthermore, as previously noted, the licensee's ITS inc udes the SFDP. The SFDP requires provisions for cross-division checks to ensure a loss of safety function assumed in the licensing basis accident analysis does not go undetected. The licensee indicated that training was provided to all licensed operations personnel prior to implementation of the ITS.

OAP 022, "BNP Outage Risk Management"is used for planning outages. Prior to an outage, the licensee reviews the planned work to ensure that high risk evolutions are clearly identified in the scheoule and that contingency plans are in place. The shutdown plant configurations are assessed using the EOOS tool, and a deterrninistic assessment for tne configurations is

4

.V 12 performed using the EPRI Oram-Sentinel code. The result is an independent analysis of compliance with OAP-022, which verifies that defense in-depth is maintained and provides simplified color grades for each safety function during every system configuration of the outage.

Also, this procedure provides guidance to assess shutdown unit work which may affect the operating unit.

Thus, for this TS amendment, the staff's Tier 2 review finds that the licensee has appropriate practices and controls in place to avoid risk-significant configurations for both units.

Tier 3: Risk informed Plant Confiauration Manaaement Tier 3 describes the CRMP which includes provisions for assessing scheduled and unscheduled plant configurations. Guidance for the requirements of a CRMP are provided in RG 1.177, "An Approach For Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications." RG 1.177 indicates that the licensee's CRMP for risk-informed TS should be described in the TS Administrative Controls section. In lieu of placing the CRMP in the TS Administrative Controls section, the licensee is placing it in the TRM, Section 5.5.13. The TRM is incorporated by reference into the UFSAR, and as such, changes to the TRM are subject to the requirements of 10 CFR 50.59. The staff finds that placing the CRMP in the TRM provides adequate assurance that future changes will receive an appropriate level of management and, if necessary, NRC staff review. A portion of the licensee's CRMP is shown below. The staff finds that the CRMP is acceptable, and the intent of Tier 3 is met.

5.5.13 Confiauration Risk Manaaement Proaram The CRMP provides a proceduralized risk-informed assessment to manage the risk associated with equipment inoperability. The program applies to TS structures, systems, or components for which a risk-informed AOT has been granted. The program shall include the following elements:

a.

Provisions for the control and implementation of a Level 1 at-power internal events PRA-informed methodology. The assessment shall be capable of evaluating the applicable plant configuration. (OAP-025) b.

Provisions for performing an assessment prior to entering the Limiting Condition for Operation (LCO) Action for preplanned activities. (OAP-025) c.

Provisions for performing an assessment after entering the LCO Action for unplanned entry into the LCO Action. (OAP-025)

I d.

Provision for assessing the need for additional actions after the discovery of additional equipment out of service conditions while in the LCO Action. (OAP-025) e.

Provisions for considering other applicable risk significant contributors such as Level 2 issues and external events, qualitatively or quantitatively. (OAP-025, ADM-NGGC-0101, OAl-068, AND OPEP-02.6)

0 a

(,

13 In summary, the staff finds that the risk associated with this TS amendment is small based on the guidance and the three-Tiered approach outlined !a RGs 1.174 and 1.177.

2.4 Overall Conclusion of 7-Day AOT Extension Through deterministic and risk evaluations, the staff finds that (1) the risk associated with this TS _

amendment is small based on the guidance and the three-Tiered approach outlined in RG.= 1.174

)

and 1.177 and (2) a longer AOT can provide additional flexibility in scheduling maintenance activities to maintain a high level of reliability for the ac electrical power distribution system. Thus the staff agrees with the licensee that any smallincreases in risk resulting from a longer AOT are offset by the improved reliability gained by allowing planned maintenance to be performed during the extended AOT. The staff concludes that the proposed extension of the AOT, as provided by the additions of ITS 3.8.1, Condition B, and ITS 3.8.7, Condition A, is acceptable.

2.5 Other Changes to Condition B and Bases B.1 of ITS 3.8.1 Current Required Action B.1 of ITS 3.8.1 states, " Declare required feature (s) with no offsite power available inoperable when the redur dant required feature (s) are inoperable." The licensee proposed to delete the word "offsite" from the above Action B.1 as the vulnerability could come from inoperable offsite circuits and an emergency diesel generator. The staff has reviewed this proposed deletion and finds that the change provides clarification and is acceptable.

The licensee proposed to modify Condition B for the operating unit by adding two notes. Note 1 i

indicates that Condition B is entered for planned maintenance only when the second unit is shut down (Mode 4 or 5). Note 2 ensures that two offsite power sources would be available for the shutdown unit when the proposed planned maintenance is performed. The staff has reviewed the notes and finds that they ensure that the unit planned for maintenance would be in a shutdown mode (i.e., Mode 4 or 5) and the two offsite power sources associated with that unit would be available to support any unforeseen events. The staff finds the proposed addition of these notes to Condition B of ITS 3.8.1 acceptable.

The licensee proposed to modify Bases B.1 of ITS B 3.8.1 bj adding (1) an example of an inoperable redundant required feature for Required Action B.1 and (2) a basis for the two aforementioned notes in Condition 8 of ITS 3.8.1. The staff has reviewed these modifications in the Bases B.1. The staff finds that the example illustrates vulnerability to a loss of safety function and the notes provide additional assurance for offsite power availability. The stafi concludes that the proposed modification of Bases B.1 of ITS B3.8.1 is acceptable.

3.0 STATE CONSULTATION

in accordance with the Commission's regulations, the State of North Carolina official was notified of the proposed issuance of the amendments. The State official had no comments.

)

k o

4' 14

4.0 ENVIRONMENTAL CONSIDERATION

The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined i

that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (63 FR 6977). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

5.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors: P. Kang D. O'Neal Date: April 15, 1999 f

l l

]

n

e

.a

![

Mr. J. S. Keenan Brunswick Steam Electric Plant l

Carolina Power & Light Company Units 1 and 2 CC:

i Mr. William D. Johnson Ms. Karen E. Long j

Vice President and Corporate Secretary Assistant Attorney General

{

Carolina Power & Light Company State of North Carolina

{

Post Office Box 1551 Post Office Box 629 1

Raleigh, North Carolina 27602 Raleigh, North Carolina 27602 Mr. Jerry W. Jones, Chairman Mr. Robert P. Gruber Brunswick County Board of Commissioners Executive Director t

Post Office Box 249

.Public Staff-NCUC Bolivia, North Carolina 28422 Post Office Box 29520 Raleigh, North Carolina 27626-0520 l

Resident inspector l

U.S. Nuclear Regulatory Commission l

8470 River Road Director l

Southport, North Carolina 28461 Site Operations Brunswick Steam Electric Plant Mr. John H. O'Neill, Jr.

Post Office Box 10429 s

L Shaw, Pittman, Potts & Trowbridge Southport, North Carolina 28461 2300 N Street, NW.

Washington, DC 20037-1128 Mr. William H. Crowe, Mayor City of Southport Mr. Mel Fry, Director 201 East Moore Street Division of Radiation Protection Southport, North Carolina 28461 I

N.C. Department of Environment and Natural Resources Mr. Dan E. Summers 3825 Barrett Dr.

Emergency Management Coordinator Raleigh, North Carolina 27609-7721 New Hanover County Department of Emergency Management Mr. J. J. Lyash Post Office Box 1525 Plant Manager Wilmington, North Carolina 28402 Carolina Power & Light Company Brunswick Steam Electric Plant Mr. Terry C. Morton Post Office Box 10429 Manager Southport, North Carolina 28461 Performance Evaluation and Regulatory Affairs CPB 9 Public Service Commission Carolina Power & Light Company State of South Carolina Post Office Box 1551 i

Post Office Drawer 11649 Raleigh, North Carolina 27602-1551 Cglumbia, South Carolina 29211 I

Mr. K. R. Jury Manager - Regulatory Affairs Carolina Power & Light Company Post Office Bcx 10429 Southport, NC 28461-0429