IR 05000277/2008007

IR 05000277-08-007, 05000278-08-007; 03/17/2008 - 04/11/2008; Peach Bottom Atomic Power Station; Component Design Bases Inspection

ML081420740
Person / Time
Site:	Peach Bottom
Issue date:	05/21/2008
From:	Doerflein L Engineering Region 1 Branch 2
To:	Pardee C AmerGen Energy Co, Exelon Generation Co
References
IR-08-007
Download: ML081420740 (36)

Text

SUBJECT:

PEACH BOTTOM ATOMIC POWER STATION - NRC COMPONENT DESIGN BASES INSPECTION REPORT 05000277/2008007 AND 05000278/2008007

Dear Mr. Pardee:

On April 11, 2008, The U.S. Nuclear Regulatory Commission (NRC) completed an inspection at the Peach Bottom Atomic Power Station (PBAPS). The enclosed inspection report documents the inspection results, which were discussed on April 11, 2008, with Mr. Michael Massaro and other members of your staff.

The inspection activities were conducted under your license as they relate to safety and compliance with the Commissions rules and regulations and with the conditions of your license.

In conducting the inspection, the team examined the adequacy of selected components and operator actions to mitigate postulated transients, initiating events, and design basis accidents.

The inspection involved field walkdowns, examination of selected procedures, calculations and records, and interviews with station personnel.

This report documents two NRC-identified findings which were of very low safety significance (Green). One of the findings was determined to involve a violation of NRC requirements.

However, because of the very low safety significance of the violation and because it was entered into your correction action program, the NRC is treating it as a non-cited violation (NCV)

consistent with Section VI.A of the NRC Enforcement Policy. If you contest the NCV or the finding in this report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U. S. Nuclear Regulatory Commission, ATTN:

Document Control Desk, Washington, D.C. 20555-0001, with copies to the Regional Administrator, Region 1; the Director, Office of Enforcement, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555-0001; and the NRC Resident Inspectors at the PBAPS. In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter, its enclosure, and your response (if any) will be available electronically for the public inspection in the NRC Public Docket Room or from the Publicly Available Records component of NRCs document system (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RA/

Lawrence T. Doerflein, Chief Engineering Branch 2 Division of Reactor Safety Docket No. 50-277, 50-278 License No. DPR-44, DPR-56 Enclosure: Inspection Report 05000277/2008007 and 05000278/2008007 w/Attachment: Supplemental Information

SUMMARY OF FINDINGS

IR 05000277/2008007, 05000278/2008007; 03/17/2008 - 04/11/2008; Peach Bottom Atomic

Power Station; Component Design Bases Inspection.

The report covers the Component Design Bases Inspection conducted by a team of four NRC inspectors and two NRC contractors. Two findings of very low risk significance (Green) were identified, one was considered to be a non-cited violation. The significance of most findings is indicated by their color (Green, White, Yellow, Red) using IMC 0609, Significance Determination Process (SDP). Findings for which the SDP does not apply may be Green or be assigned a severity level after NRC management review. The NRCs program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process, Revision 4, dated December 2006.

Cornerstone: Mitigating Systems

Green.

The team identified a finding of very low safety significance involving a non-cited violation of Technical Specification (TS) 3.8.4.5, in that Exelon did not verify certain battery connection resistances were within the TS limit. Specifically,

Exelon did not verify the inter-tier connection resistances to be within the TS 3.8.4.5 limit of less than or equal to 40 micro-ohms every 12 months. The team determined that Exelon exempted the inter-tier connections from the testing requirement. In response, Exelon performed the required testing and identified a connection in the 2B battery that was greater than the TS limit. Exelon restored the degraded connection and initiated actions to revise the surveillance test procedures to incorporate all battery connections.

This issue was more than minor because it was associated with the procedure quality attribute of the Mitigating Systems cornerstone and affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences.

The team determined the finding was of very low safety significance (Green)because it did not result in a loss of safety system function. Because the licensee had previously identified a similar inadequacy in the test procedure, the finding had a cross-cutting aspect in the area of Problem Identification and Resolution - Corrective Actions. (IMC 0305, aspect P.1(d)) (1R21.2.1.1)

• Green: The team identified a finding of very low safety significance, in that Exelon failed to use appropriate inputs in design calculations as required by Exelon Procedure CC-AA-102 - Design Input and Configuration Change Impact Screening. The requirements of the procedure include ensuring performance requirements are the maximum or minimum numerical values of specific design parameters, specifically, the Maximum time to automatically initiate a system action. The team determined the response speed used by Exelon for the automatic load tap changer (LTC) controller and mechanism for the stations startup transformers, in the calculation to determine offsite power availability, was non-conservative. This assumption resulted in the grid voltage limit, used to assess technical specification offsite power supply operability, to be non-conservative. In response, Exelon performed preliminary calculations with ii

revised LTC times, which showed that the offsite grid remained operable at the specified voltage limits. Exelon entered the issue into the corrective action program to re-perform the calculation and raise the allowed offsite grid voltage level.

This finding was more than minor because it is associated with the Mitigating Systems Cornerstone and affected the cornerstone objective of ensuring the availability, reliability and capability of systems that respond to initiating events to prevent undesirable consequences. The team determined the finding was of very low safety significance (Green) because it was design deficiency that did not result in a loss of offsite power operability. Because the licensee had recently performed this calculation with the non-conservative inputs, the finding has a cross-cutting aspect in the area of Human Performance - Resources. (IMC 0305, aspect H.2.(c)) (1R21.2.1.4)

B. Licensee-Identified Violation None iii

REPORT DETAILS

1R21 Component Design Bases Inspection (IP 71111.21)

.1 Inspection Sample Selection Process

The team selected risk significant components and operator actions for review using information contained in the Peach Bottom Atomic Power Station (PBAPS) Probabilistic Risk Assessment (PRA) and the U. S. Nuclear Regulatory Commissions (NRC)

Standardized Plant Analysis Risk (SPAR) model. Additionally, the PBAPS Significance Determination Process (SDP) Phase 2 Notebook, Revision 2, was referenced in the selection of potential components and operator actions for review. In general, the selection process focused on components and operator actions that had a Risk Achievement Worth (RAW) factor greater than 1.3 or a Risk Reduction Worth (RRW)factor greater than 1.005. The components selected were located within both safety-related and non-safety related system, and included a variety of components such as pumps, breakers, heat exchangers, generators, transformers, and valves.

The team reviewed a list of components and operator actions based on the risk factors previously mentioned. Additionally, the team reviewed the previous component design bases inspection report (05000277, 278/2006009) and excluded those components previously inspected. The team then performed a margin assessment to narrow the focus of the inspection to 24 components and 4 operator actions. The teams evaluation of possible low design margin included consideration of original design issues, margin reductions due to modifications, or margin reductions identified as a result of material condition/equipment reliability issues. The assessment also included items such as failed performance test results, correction action history, repeated maintenance, maintenance rule (a)1 status, operability reviews for degraded conditions, NRC resident inspector insights, system health reports, and industry operating experience. Finally, consideration was also given to the uniqueness and complexity of the design and the available defense-in-depth margins. The margin review of operator actions included complexity of the action, time to complete the action, and extent of training on the action.

The inspection performed by the team was conducted as outlined in Inspection Procedure (IP) 71111.21. This inspection effort included walkdowns of selected components, interviews with operators, system engineers and design engineers, and reviews of associated design documents and calculations to assess the adequacy of the components to meet design basis, licensing basis, and risk-informed beyond design basis requirements. A summary of the reviews performed for each component, operator action, operating experience sample, and the specific inspection findings identified are discussed in the subsequent sections of this report. Documents reviewed for this inspection are listed in the Attachment.

.2.1.1 125/250 Vdc Station Batteries 2B, 2D, 3A, and 3C

a. Inspection Scope

The team inspected the 2B, 2D, 3A, and 3C station batteries to verify they were adequately sized to supply the design duty cycle of the 125/250 volts direct current (Vdc)systems for the loss-of coolant accident/loss-of-offsite power and station blackout loading scenarios. The team reviewed calculations to verify that the sizing of the batteries would satisfy the requirements of the safety related and risk significant direct current (DC) loads, and that the minimum possible voltage was taken into account. In particular, the evaluation focused on voltage drop calculations to ensure that adequate voltage would remain available for the individual loads required to operate during the design basis events. Plant drawings were reviewed to ensure that all loads were considered. Additionally, battery charger sizing calculations were reviewed to verify consistency with the design and licensing bases. The team reviewed the DC protective coordination study to verify that adequate protection exists for postulated faults in the DC system. The team reviewed the battery room hydrogen generation calculation to verify that the hydrogen concentration levels would stay below acceptable levels during normal and accident conditions. A walkdown was performed to evaluate the material condition of the batteries and battery chargers. The team reviewed battery surveillance test procedures and results to determine whether test acceptance criteria and frequency requirements specified in technical specifications and associated battery testing standards were satisfied. Finally, system and design engineers were interviewed regarding design aspects and operating history of the batteries, and condition reports were selected to verify that design and testing issues related to the batteries were identified and corrected.

b. Findings

Introduction:

The team identified a finding of very low safety significance (Green)involving a non-cited violation (NCV) of Technical Specification (TS) 3.8.4.5, in that, Exelon did not verify certain battery connection resistances were within the TS limit.

Specifically, Exelon did not verify the inter-tier connection resistances to be within the TS 3.8.4.5 limit of less than or equal to 40 micro-ohms every 12 months. Exelon exempted the inter-tier connections from the testing requirement.

Description:

The team reviewed the annual surveillance test results for the station batteries to ensure that connection resistances were being measured in accordance with IEEE Standard 450-1995 and to ensure that the values were within the TS limit. The team determined battery connection resistances were measured during surveillance ST-M-57B-7XX-X, Battery Yearly Inspection, and also during the biennial discharge tests.

The test procedures state, Acceptance Criteria: All Ductor Readings <= 40 micro ohms with the exception of the tier-to-tier and rack-to-rack connection jumpers. Tier-to-tier and rack to rack connections, commonly referred to as inter-tier connections, are connections between cells using cables vise steel bars. The team found that TS 3.8.4.5 requires that all battery connection resistances be verified less than or equal to 40 micro-ohms every 12 months, and does not provide for the exemption of any connections.

Therefore, the team concluded that Exelon was not meeting the TS surveillance requirement because acceptance criteria for the inter-tier connections had been exempted from the surveillance procedure.

Exelon entered the issue into the corrective action program and took immediate steps to the resolve the deficiency. This included a review of other tests performed on the Unit 2 and 3 station batteries. For the Unit 3 batteries, documentation from biennial discharge testing showed tier-to-tier resistances were measured in September 2007 and were within the TS limit. For Unit 2, Exelon determined that no data was measured for the inter-tier connections that met the TS yearly frequency requirement. Exelon performed the resistance testing for the Unit 2 batteries and determined one of four cables on the lug to post connection for cell 14 of the 2B battery was above the TS limit with a reading of 44 micro-ohms. Exelon declared the battery inoperable and retorqued the connection in accordance with IEEE 450-1995. The surveillance was then satisfactorily re-performed (32 micro-ohms) and the TS action statement exited. Additionally, Exelon performed an operability evaluation which determined that the degraded connection on the 2B battery would not have prevented the battery from fulfilling its safety function.

The calculation showed that sufficient voltage drop margin across the battery existed and the heating of the connection would not be sufficient to cause damage. The team independently calculated the impact and agreed with Exelons conclusions. Finally, Exelon intends to revise the surveillance test procedures to ensure all battery connections are measured in accordance with TS.

The team also identified that in June 2007 Exelon staff identified in a condition report (CR) that the annual inspection surveillance test was not adequate. The CR recommended the surveillance test be revised to include acceptance criteria for inter-tier connection resistances. However, the CR was closed without adequately addressing the issue.

Analysis:

The team determined Exelons failure to verify all battery connection resistances were within the limit of TS 3.8.4.5 was a performance deficiency that was reasonably within Exelons ability to foresee and prevent. The finding was more than minor because it was similar to NRC Inspection Manual Chapter 0612, Appendix E, Examples of Minor Issues, example 4.I., in that the TS required surveillance was not performed until prompted by the team and one connection on the 2B battery was found to be greater the TS limit. The finding was associated with the procedure quality attribute of the Mitigating Cornerstone and affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. In accordance with NRC Inspection Manual Chapter 0609, Attachment 4, "Phase 1 - Initial Screening and Characterization of Findings," a Phase 1 SDP screening was performed and determined the finding was of very low safety significance (Green) because it was not a design or qualification deficiency, did not result in an actual loss of safety system function, and did not screen as potentially risk significant due to a seismic, flooding, or severe weather initiating event.

The finding has a cross-cutting aspect in the area of Problem Identification and Resolution which requires licensees to take appropriate corrective actions to address safety issues and adverse trends in a timely manner, commensurate with their safety significance and complexity. Specifically, Exelon did not address this issue when it was identified in June 2007. (IMC 0305, aspect P.1(d))

Enforcement:

Technical Specification 3.8.4.5 requires that, every 12 months, Exelon verify battery connection resistance is less than or equal to 40 micro-ohms. Contrary to the above, prior to April 1, 2008, Exelon exempted the battery intertier connections from the TS 3.8.4.5 requirement. Because this violation is of very low safety significance and has been entered into Exelons corrective action program (AR 757374757374, this violation is being treated as a non-cited violation consistent with Section VI.A.1 of the NRC Enforcement Policy. (NCV 05000277/2008007-01, Inadequate Battery Connection Resistance Testing)

.2.1.2 4kV Supply breaker - E212 (Loss of E12 - fast Transfer to E312 or EDG E12)

a. Inspection Scope

The team inspected the 4kV supply breaker to verify it could respond to design basis events as described in the UFSAR and PRA. The team reviewed 125Vdc voltage drop calculations and battery test results to determine whether the breaker controls would have adequate voltage to operate when required. The team reviewed bus and breaker elementary diagrams to verify control logic for breaker operation was consistent with the design bases. The team reviewed alternating current (AC) load flow and protective relay calculations to determine whether overcurrent protection was appropriate for accident loading. The team reviewed system health, maintenance, and corrective action documents to determine whether the equipment has exhibited adverse performance trends. The team also performed a visual inspection of the 4kV switchgear to assess materiel condition and the presence of hazards. Finally, the team reviewed vendor maintenance recommendations and station maintenance procedures to determine whether proper maintenance was being performed.

b. Findings

No findings of significance were identified.

.2.1.3 Number 2 Emergency Aux Transformer (0AX04)

a. Inspection Scope

The team inspected the emergency auxiliary transformer to verify it could respond to design basis events as described in the UFSAR and PRA. The team reviewed AC load flow calculations to determine whether the transformer had sufficient capacity to support calculated loading under worst case accident loading and grid voltage conditions. The team reviewed transformer protective relaying to determine if adequate protection was provided and whether there would be any adverse interactions that would reduce system reliability. The team reviewed maintenance procedures to determine whether tasks and acceptance criteria were consistent with vendor recommendations. The team performed a visual inspection of the Number 2 Emergency Aux Transformer to assess materiel condition and the presence of hazards. In addition, the team reviewed maintenance records, system health data, and corrective action documents to determine whether there were any adverse equipment operating trends.

b. Findings

No findings of significance were identified.

.2.1.4 343 Startup Transformer (00X11)

a. Inspection Scope

The team inspected the 343 startup transformer to determine if it was adequate to respond to a DBE. The team reviewed AC load flow calculations to determine whether the transformer had sufficient capacity to support its required loads under worst case accident loading and grid voltage conditions. The team reviewed transformer protective relaying to determine if it afforded adequate protection and whether there would be any adverse interactions that would reduce system reliability. The team reviewed maintenance procedures to determine whether tasks and acceptance criteria were consistent with vendor recommendations. The team reviewed design parameters for the automatic load tap changers and compared them with criteria in calibration procedures and design calculations to determine whether they were in alignment. The team performed a visual inspection of the No. 343 Startup Transformer and the 230kV switchyard to assess materiel condition and the presence of hazards. In addition, the team reviewed maintenance records, system health data, and corrective action documents to determine whether there was any adverse equipment operating trends.

b. Findings

Introduction:

The team identified a finding of very low safety significance (Green), in that Exelon failed to use appropriate inputs for design calculations as required by Exelon Procedure CC-AA-102 - Design Input and Configuration Change Impact Screening.

Specifically, the response speed used for the automatic load tap changer (LTC) controls and mechanism for the 2SU, 3SU, and 343SU transformers, used in Exelons calculation to determine offsite power operability, was non-conservative. The speed assumption used in the calculation resulted in the minimum grid voltage limit provided to the offsite grid operator to be non-conservative.

Description:

The team reviewed Exelons evaluation that assessed the operability of offsite power supplies. The team reviewed calculation PE-0121 which was developed to assess what grid voltage levels were adequate to ensure offsite power was available to the 4160 volt vital buses during design basis events. One input to this calculation was the time response of the automatic load tap changers of the startup transformers (2SU, 3SU, and 343SU). The calculation methodology determines if voltage on the vital bus is adequate by determining when the LTC would start to operate and when the degraded voltage relay scheme would actuate and reset. Each movement of the tap changer results in an increase of voltage level on the vital bus. The results of the calculation showed that several tap changer operations would be required to recover bus voltage above the degraded grid reset voltage prior to the relay timing out and thus preventing an inadvertent transfer of 4160 volt busses away from the offsite source.

The team evaluated the accuracy of two critical parameters in the calculation. These were the initial controller time delay before LTC movement, and the time for the LTC mechanism to move between successive taps. The team determined that the values used calculation PE-0121 for both of these parameters were non-conservative. For the controller time delay Exelon assumed a nominal value of 3 seconds for the calculation, whereas the acceptance criteria in maintenance procedures was 3 +/- 0.3 seconds.

Additionally, the team determined the as-left value for the 343SU transformer at the last calibration was 3.2 seconds. Exelon also used 5 seconds for the time between taps; however, the team reviewed results of recent tap changer speed tests which showed actual times of 5.18 seconds for the 2SU transformer and 5.25 seconds for the 343SU transformer.

In response to the teams concern, the licensee performed preliminary calculations for the most limiting alignment with the revised tap changer times. The results showed that the offsite grid remained operable at the specified voltage limits. Exelon entered the issue into the corrective action program to re-perform the calculation and raise the allowed offsite grid voltage level. Additionally, the inspectors also noted that the actual as-left field settings of the degraded voltage reset function were below their maximum analyzed value providing additional margin for offsite power operability.

Analysis:

The performance deficiency associated with this finding was that the licensee failed to use appropriate inputs in design calculations as was required by Exelon Procedure CC-AA-102 - Design Input and Configuration Change Impact Screening. The requirements of the procedure include ensuring performance requirements are the maximum or minimum numerical values of specific design parameters including Maximum time to automatically initiate a system action. In this case Exelon did not assume the maximum possible time for the tap changer operation in their calculation.

The finding was more than minor because it was similar to NRC Inspection Manual Chapter 0612, Appendix E, Examples of Minor Issues, example 3.j., in that the calculation deficiencies represented reasonable doubt regarding the operability of the offsite power supply. This finding was associated with the design control attribute of the Mitigating Systems Cornerstone and affects the cornerstone objective of ensuring the availability, reliability and capability of systems that respond to initiating events to prevent undesirable consequences. In accordance with NRC Inspection Manual Chapter 0609, Attachment 4, "Phase 1 - Initial Screening and Characterization of Findings," a Phase 1 SDP screening was performed and determined the finding was of very low safety significance (Green) because it was a design deficiency confirmed not to result in a loss of offsite power operability.

The finding has a cross-cutting aspect in the area of Human Performance - Resources which requires licensees to ensure personnel, equipment, procedures, and other resources are available and adequate to assure nuclear safety. This issue is related to design calculations not being complete, accurate and up-to-date. Specifically, Exelon did use conservative inputs when determining offsite grid voltage operability limits during a recent revision to the calculation (IMC 0305, aspect H.2(c)).

Enforcement:

Offsite power is considered non-safety related, therefore, enforcement action does not apply because the associated performance deficiency did not involve a violation of regulatory requirements. The licensee has entered this item into their corrective action program as AR00759547. (FIN 05000277;278/2008007-02, Non-conservative Inputs Used in Design Calculations for Offsite Power Operability)

.2.1.5 Unit 2 High Pressure Coolant Injection Division 2 Logic

a. Inspection Scope

The team reviewed High Pressure Coolant Injection (HPCI) logic drawings to determine whether system functions including initiation, interlocks, and protective device actuations were consistent with the Updated Final Safety Analysis Report (UFSAR) and design basis documents (DBD). The team reviewed HPCI logic test procedures to determine whether the test adequately confirmed the operability of required functions of the system. The team reviewed maintenance records and operating experience, including 10 CFR Part 21 reports, to identify any actual or latent issues related to HPCI logic components.

b. Findings

No findings of significance were identified.

.2.1.6 Emergency Cooling Tower

a. Inspection Scope

The team inspected the Emergency Cooling Tower (ECT) to assess the capability of the tower to perform the heat removal function during the loss of the Conowingo Pond design basis event (DBE). The team reviewed safety evaluation reports (SER), DBDs, and TS requirements to determine the licensing requirements for the tower. Additionally, the team conducted a walkdown of the ECT and related systems and reviewed surveillance test results, inservice test results and a sampling of issue reports to ascertain the material condition and ability of the system to operate as designed. The team also reviewed construction drawings, design specifications, and licensee analyses to show that the ECT could remove heat at design basis conditions. Finally, the team reviewed operating procedures and job performance measures to assess the capability of the tower to operate as designed.

b. Findings

No findings of significance were identified.

.2.1.7 Control Rod Drive Pump (3A)

a. Inspection Scope

The team inspected 3A Control Rod Drive (CRD) Pump to assess the pumps capability to operate during accident conditions as assumed in the PBAPS PRA. Although the CRD pumps are not safety related, the PRA credits the equipment for the mitigation of some beyond design basis transients and accidents. The team walked down the pump, reviewed DBDs, surveillance test results, system health reports, operator routine inspection procedure results and a sampling of issue reports to ascertain the material condition and ability of the pump to perform as credited in the analysis.

b. Findings

No findings of significance were identified.

.2.1.8 Residual Heat Removal Heat Exchanger High Pressure Service Water

Valve (MO-2-10-89D) and Low Pressure Coolant Injection Motor Operated Throttle Valve (MO-3-10-154B)

a. Inspection Scope

The team reviewed the design and current material condition of the residual heat removal (RHR) heat exchanger high pressure service water (HPSW) throttle valve and the low pressure coolant injection (LPCI) motor operated throttle valve to ensure that the equipment was capable of meeting the design requirements. The team reviewed calculations including thrust requirements and maximum differential pressure to verify the ability of the motor operated valves (MOV) to operate during DBE, transient and accident conditions. Additionally, the team reviewed AC load flow and valve voltage calculations to determine whether adequate motive power was available during worst case degraded voltage and service conditions, and reviewed motor control center control circuit voltage drop calculations to determine whether MOV contactors had adequate voltage to pick up when required. The team reviewed elementary wiring diagrams to determine whether control logic was in conformance with the design bases. Finally, the team reviewed piping and instrumentation diagrams (P&IDs), inservice test (IST) results, the MOV DBD, system operating procedures, a sample of issue reports and conducted a walkdown of the valves to assess the material condition of the valves and capability to operate during DBEs.

b. Findings

Unresolved Item: The team reviewed Exelons load flow and vital bus voltage calculations. The review was performed to verify the minimum vital bus voltage needed to ensure operation of safety related loads required during design basis events was adequate. The team determined that voltages used in these analyses were not based on the trip set point of the Technical Specification Function 4 (LOCA) degraded voltage relay. Exelon had used voltages higher than were afforded by the Function 4 relays based on their belief that minimum expected value, as defined in GL 79-36 - Adequacy of Station Electric Distribution Systems Voltage, could be used to calculate adequate voltages to vital loads. In using this assumption Exelon credited voltage improvement due to operation of the non-safety related startup transformer load tap changers in their analysis. The tap changer restores voltage to the vital bus during and following the post accident voltage transient. The team reviewed NRC Letter dated June 2, 1977, which was the basis for the licensing requirement to install the degraded voltage relay protection scheme. This licensing requirement required the set points for the second level reduced-voltage relays provide adequate voltage, from offsite or onsite power sources, for safety related loads at all onsite system distribution levels. The inspectors reviewed the PBAPS licensing records related to degraded voltage protection and did not find where the NRC had allowed Peach Bottom to credit operation of automatic tap changers in lieu of the technical specification reduced voltage relays to provide protection. Exelon stated that their approach was acceptable and the NRC had given this credit when it reviewed and approved certain voltage studies submitted as part of licensing actions related to the degraded voltage relays. This unresolved issue is being opened to determine if the Peach Bottom approved licensing bases includes the use of automatic load tap changers to protect the vital bus from unacceptable low voltage conditions during loss of coolant accidents. (URI 05000277;278/2008007-003, Vital Bus Degraded Voltage Protection)

.2.1.9 Sluice Gate (MO-2-30-2233A)

a. Inspection Scope

The team reviewed the design and current condition of a pump house sluice gate to ensure that the equipment was capable of meeting the design requirements. The team reviewed calculations including thrust requirements and maximum differential pressure to verify the ability of the MOV to operate during a DBE. The team reviewed P&IDs, IST results, design calculations, operating procedures, and a sample of issue reports, and conducted a walk-down of the sluice gate to assess the capability to operate during a Loss of Conowingo Pond event.

b. Findings

No findings of significance were identified.

.2.1.1 0 Residual Heat Removal Heat Exchanger (3D)

a. Inspection Scope

The team reviewed the design and current condition of the RHR heat exchanger to ensure the equipment was capable of meeting its design requirements. The team reviewed design basis documents, calculations, performance test results, operability determinations, and a sample of issue reports to assess the capability of the heat exchanger to perform under design basis conditions. Additionally, the team conducted a walkdown the heat exchanger to assess its material condition.

b. Findings

No findings of significance were identified.

.2.1.1 1 B Emergency Diesel Generator Cooler Outlet Emergency Service Water Air

Operated Block Valve (AOV-241B)

a. Inspection Scope

The team reviewed the design and current condition of the air operated block valve. The valve is normally held closed by air pressure and opens to allowed emergency service water to flow through the emergency diesel generator (EDG) coolers to remove heat generated during EDG operation. The valve has a safety function to open. The team reviewed P&IDs, IST results, and a sample of issue reports, and conducted a walkdown of the valve to assess the capability to operate during a DBE.

b. Findings

No findings of significance were identified.

.2.1.1 2 Unit 3 Reactor Core Isolation Cooling Steam Admission Valve (MO-13-131) and

Injection Valve (MO-13-21), and Unit 2 High Pressure Coolant Injection System Steam Admission Valve (MO-23-14)

a. Inspection Scope

The team inspected the Unit 3 Reactor Core Isolation Cooling (RCIC) injection valve, the Unit 3 RCIC steam admission valve, and the Unit 2 HPCI steam admission valve to verify they would operate during design basis events. The inspection included interviews with system and design engineers, and reviews of drawings and calculations to determine the assumptions used in the analytical analysis developed to confirm valve operation. The team verified the assumptions used in the analysis were appropriate.

The team verified that the calculations for valve operation and torque limit settings used the maximum differential pressure expected across the valves during worst case operating conditions. The team also reviewed the analysis of the valve motor to perform its design function under accident conditions. The team reviewed associated electrical calculations to confirm that the design basis minimum voltage at the motor terminals would be adequate for starting and running the motor. The protective device/thermal overload relay settings were reviewed to ensure that adequate margin existed. A review of the cables sizing was performed to ensure ampacity levels were not exceeded for all motor operating conditions. The team also reviewed the breaker closure and opening control logic diagrams and the control circuit voltage calculations to ensure adequate voltage would be available for the control circuit components. The team reviewed periodic verification test results and valve stroke time testing to verify that the MOVs continued to be capable of performing their safety function and that torque switch settings were correct in accordance with Generic Letter (GL) 89-10 guidance.

Additionally, the team reviewed MOV periodic performance test results to verify that changes in valve performance due to degradation were properly identified and that test frequency was correctly determined based on the results as described in GL 96-05.

Finally, the team reviewed condition reports and system health reports to determine the overall health of the valves, and determine if issues entered into the corrective action program were appropriately addressed.

b. Findings

No findings of significance were identified.

.2.1.1 3 Unit 2 Inboard and Outboard Main Steam Isolation Valve (AO-2-80C & AO-2-86C)

a. Inspection Scope

The team inspected the Unit 2 C inboard and outboard main steam isolation valves (MSIV) to verify they would operate during design basis events. The inspection included interviews with system and design engineers, and reviews of drawings and calculations to determine the assumptions used in the analytical analysis for valve operation. The team verified the assumptions used in the analysis were in agreement with the design basis and operating procedures. The team verified that the valve analysis used the maximum differential pressure expected across the valves during worst case operating conditions. The team also reviewed the analysis of the valve air operator to perform its design function under accident conditions. The team reviewed periodic verification test results and valve stroke time testing to verify that the air operated valves (AOV)continued to be capable of performing their safety function. Additionally, the team reviewed AOV periodic performance test results to verify that changes in valve performance due to degradation were properly identified and that test frequency was correctly determined based on the results. Finally, the team reviewed condition reports and system health reports to determine the overall health of the valves, and determine if issues entered into the corrective action program were appropriately addressed.

b. Findings

No findings of significance were identified.

.2.1.1 4 Unit 2 High Pressure Coolant Injection System Turbine (23-20S037) and HPCI Lube Oil

Cooler (23-20E105)

a. Inspection Scope

The team inspected the Unit 2 HPCI turbine to verify that the turbine would meet the design basis requirements. The inspection included a review of turbine and governor cooling, including associated instrumentation, control and annunciator logic, to determine if the manufacturer and EPRI range for the lube oil pressures were maintained during all operating conditions. The team performed a walkdown of the turbine and associated support features, interviewed system and design engineers, and reviewed HPCI system health reports and conditions reports to assess the material condition of the components. The team also reviewed the TS, UFSAR, HPCI DBD, and design bases calculations to determine the required flows, pressures, and operating conditions for various system configurations. Additionally, the team evaluated calculations, technical evaluations, pump curves, condition reports, and IST data. The review assessed whether TS and design basis requirements could be achieved and IST acceptance criteria were appropriate. The team also reviewed the HPCI lube oil cooler heat transfer calculations, periodic inspection results, tube plugging limits, and current tube plugging to verify that design basis heat removal requirements were satisfied.

Finally, the team reviewed condition reports and system health reports to determine the overall health of the system, and determine if issues entered into the corrective action program were appropriately addressed.

b. Findings

No findings of significance were identified.

.2.1.1 5 Unit 2 Residual Heat Removal Pump (10-2AP035)

a. Inspection Scope

The team inspected the Unit 2 RHR pump to verify that the pump would meet the design basis requirements. The inspection included a review of pump minimum flow provisions, including associated instrumentation and control logic, to determine if pump manufacturer minimum flow levels were maintained during all operating conditions. The team interviewed system and design engineers, and reviewed RHR system health reports and condition reports to assess the material condition of the component. The team also reviewed the TS, UFSAR, RHR DBD, and design bases calculations to determine the required flows, pressures, and operating conditions for various system configurations. Additionally, the team evaluated calculations, technical evaluations, pump curves, condition reports, and IST data. This evaluation assessed whether TS and design basis requirements could be achieved, net positive suction head and minimum flow requirements were met, and IST acceptance criteria were appropriate.

The team also reviewed AC load flow and voltage calculations to determine whether adequate motive power was available during worst case degraded voltage and service conditions. The team reviewed elementary wiring and logic diagrams to determine whether motor control logic was in conformance with the design bases. Finally, the team reviewed condition reports and system health reports to determine the overall health of the system, and determine if issues entered into the corrective action program were appropriately addressed.

b. Findings

No findings of significance were identified.

.2.1.1 6 125 Vac Static Inverter

a. Inspection Scope

The team reviewed the design and testing of the 125 Vac static inverter to ensure it could perform its design function of providing a reliable source of power to its associated busses and components during normal, transient and accident conditions. The team reviewed the load calculations, control diagrams, past corrective actions, and component vendor manuals. The review was performed to verify the load analyses included all operating equipment supplied from the inverter, assumptions agreed with operating procedures, and calculation methodologies were accurately performed. In addition, a walkdown was performed to visually inspect the material condition of the inverter.

b. Findings

No findings of significance were identified.

.2.2 Detailed Operator Action Reviews (4 samples)

The team assessed manual operator actions and selected a sample of four operator actions for detailed review based upon risk significance, time urgency, and factors affecting the likelihood of human error. The operator actions were selected from a PRA ranking of operator action importance based on RAW and RRW values. The non-PRA considerations in the selection process included the following factors:

$ Margin between the time needed to complete the actions and the time available prior to adverse reactor consequences.

$ Complexity of the actions.

$ Reliability and/or redundancy of components associated with the actions.

$ Extent of actions to be performed outside of the control room.

$ Procedural guidance to the operators.

$ Amount of relevant operator training conducted.

.2.2.1 Operators Maximize Control Rod Drive Flow for Reactor Pressure Vessel Injection

a. Inspection Scope

The team inspected the operator action to maximize CRD flow for reactor pressure vessel injection per operating procedure T-246. The team reviewed Exelons PRA and Human Reliability Analysis (HRA) studies to determine when and how quickly operators should maximize CRD flow for PRA success. The team interviewed licensed operators, reviewed various procedures and job performance measures, walked down applicable panels in the main control room, and observed an equipment operator simulate the in-field portions of the procedure to evaluate the ability of the operators to perform the required actions.

b. Findings

No findings of significance were identified.

.2.2.2 Operators Refill the Condensate Storage Tank from the Refuel Water Storage Tank

a. Inspection Scope

The team inspected the operator action to refill the condensate storage tank from the refuel water storage tank (RWST) using the gravity feed method. The team reviewed Exelons PRA and HRA calculations to determine when the action is credited and the amount of time available for the operators to complete the action. The inspectors conducted interviews and walked down plant areas to evaluate the ability of the operators to perform necessary actions and identify unforeseen operator challenges.

The team also reviewed procedures to ensure that actions described in the procedure would accomplish the intended function. Lastly, the team reviewed calculations that established required RWST inventory, and the administrative controls to maintain adequate level in the RWST for PRA success. Finally, the team verified the material condition of manipulated valves was satisfactory.

b. Findings

No findings of significance were identified.

.2.2.3 Operators Cross Tie 4kV Emergency Busses

a. Inspection Scope

The team inspected the operator action to cross tie 4kV emergency busses during a loss-of-offsite power event when two emergency diesel generators have failed to start.

The inspectors reviewed Exelons PRA and HRA calculations to determine when this action is credited and the time available for operators to perform this action. The team interviewed licensed and non-licensed operators, reviewed various procedures and training documents, walked down switchgear in the plant and applicable panels in the main control room, and observed in-plant and control room operators simulate the associated procedure steps. The team used the results of these inspection techniques to evaluate the ability of the operators to correctly perform the required actions in the time allotted in the HRA calculations.

b. Findings

No findings of significance were identified.

.2.2.4 Operators Initiate Containment Venting via the Torus Hardened Vent Upon Loss of

Containment Heat Removal

a. Inspection Scope

The team inspected the operator action to initiate containment venting via the torus hardened vent upon loss of containment heat removal. The team reviewed Exelons PRA and HRA studies to determine when these actions are required and the time available for operators to perform this action. The inspectors conducted interviews, reviewed training documents and procedures, walked down applicable panels in the main control room, and observed equipment operators simulate in-field actions. The inspectors also verified that emergency equipment, such as fuses and jumpers, was staged and administratively controlled to facilitate rapid operator response. The team used the results of these inspection techniques to evaluate the ability of the operators to correctly perform the required actions in the time allotted in the HRA calculations.

b. Findings

No findings of significance were identified.

.2.3 Review of Industry Operating Experience and Generic Issues (1 sample)

a. Inspection Scope

The team performed a detailed review of Exelons evaluation of Information Notice (IN)2005-30, Safe Shutdown Potentially Challenged by Unanalyzed Internal Flooding Events and Inadequate Design. This IN discussed the potential susceptibility of safe shutdown systems to internal flood sources. The team verified that Exelon had appropriately assessed the operational experience, and if required, taken actions to ensure the same issues would not occur at PBAPS. The team noted that Exelons response included reviews of reactor building design, equipment layout and elevation, floor drain configurations, adequacy of flood barriers and penetration seals, and potential internal flood sources. Additionally, the team independently walked down areas of the plant to determine if internal flooding sources had been appropriately identified and evaluated.

b. Findings

No findings of significance were identified.

4OA2 Identification and Resolution of Problems (IP 71152)

a. Inspection Scope

The team reviewed a sample of problems that Exelon had previously identified and entered into their corrective action program. The team reviewed these issues to verify an appropriate threshold for identifying issues and to evaluate the effectiveness of corrective actions. In addition, CRs written on issues identified during the inspection were reviewed to verify adequate problem identification and incorporation of the problem into the corrective action system. The specific corrective action documents that were sampled and reviewed by the team are listed in the attachment.

b. Findings

No findings of significance were identified.

4OA6 Meetings, including Exit

The inspectors presented the inspection results to Mr. Michael Massaro, and other members of Exelons staff on April 11, 2008. The inspectors verified that none of the information in this report is proprietary.

ATTACHMENT

SUPPLEMENTAL INFORMATION

KEY POINTS OF CONTACT

Licensee Personnel

M. Massaro Plant Manager

C. Behrend Engineering Director

P. Rau Sr. Manager Design Engineering

B. Frassen Shift Operations Manager

P. Navin Senior Manager Plant Engineering

J. Armstrong Regulatory Assurance Manager

J. Kozakowski Senior Staff Engineer

J. Chizever Mechanical Design Engineer

A. Knoll Risk Assessment

LIST OF ITEMS

Opened and Closed

NCV

05000277/2008007-01 Inadequate Battery Connection Resistance Testing (Section 1R21.2.1.1)

Finding

05000277-278/2008007-02 Non-conservative Inputs Used in Design Calculations for Offsite Power Operability (Section 1R21.2.1.4)

Opened

URI

05000277-278/2008007-03 Vital Bus Degraded Voltage Protection (Section 1R21.2.1.8)