IR 05000352/2008002
| ML081270551 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 05/06/2008 |
| From: | Paul Krohn Reactor Projects Region 1 Branch 4 |
| To: | Pardee C Exelon Generation Co |
| KROHN P, RI/DRP/PB4/610-337-5120 | |
| References | |
| IR-08-002 | |
| Download: ML081270551 (38) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION May 6, 2008
SUBJECT:
LIMERICK GENERATING STATION - NRC INTEGRATED INSPECTION REPORT 05000352/2008002 AND 05000353/2008002
Dear Mr. Pardee:
On March 31, 2008, the U. S. Nuclear Regulatory Commission (NRC) completed an inspection at your Limerick Generating Station Units 1 and 2. The enclosed integrated inspection report documents the inspection results which were discussed on April 10, 2008, with Mr. C. Mudrick and other members of your staff.
The inspection examined activities conducted under your license as they relate to safety and compliance with the Commissions rules and regulations and with the conditions of your license.
The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel.
This report documents three findings of very low safety significance (Green). One of these findings was determined to involve a violation of an NRC requirement. However, because of the very low safety significance and because it is entered into your corrective action program (CAP),
the NRC is treating the finding as a non-cited violation (NCV), consistent with Section V1.A.1. of the NRC Enforcement Policy. If you contest the NCV in this report, you should provide a response within 30 days of the date of this inspection report, with basis for your denial, to the Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-001; with copies to the Regional Administration, Region 1; the Director, Office of Enforcement, United States Nuclear Regulatory Commission, Washington, DC 20555-001; and the NRC Resident Inspector at the Limerick facility.
In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the
Mr. NRC Public Document Room or from the Publicly Available Records (PARS) component of the NRCs document system (ADAMS). ADAMS is accessible from the NRC Website at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Sincerely,
/RA/
Paul G. Krohn, Chief Projects Branch 4 Division of Reactor Projects Docket Nos: 50-352, 50-353 License Nos: NPF-39, NPF-85 Enclosure: Inspection Report 05000352/2008002 and 05000353/2008002 w/Attachment: Supplemental Information cc w/encl:
C. Crane, Executive Vice President and Chief Operating Officer, Exelon Generation M. Pacilio, Chief Operating Officer, Exelon Generation Company, LLC C. Mudrick, Site Vice President - Limerick Generating Station E. Callan, Plant Manager, Limerick Generating Station R. Kreider, Regulatory Assurance Manager R. DeGregorio, Senior Vice President, Mid-Atlantic Operations K. Jury, Vice President, Licensing and Regulatory Affairs P. Cowan, Director, Licensing B. Fewell, Associate General Counsel Correspondence Control Desk D. Allard, Director, PA Department of Environmental Protection J. Johnsrud, National Energy Committee, Sierra Club Chairman, Board of Supervisors of Limerick Township J. Powers, Director, PA Office of Homeland Security R. French, Director, PA Emergency Management Agency
M
SUMMARY OF FINDINGS
IR 05000352/2008002, 05000353/2008002; 01/01/2008 - 03/31/2008; Limerick Generating
Station, Units 1 and 2; Maintenance Effectiveness, Operability Evaluations, and Refueling and Outage Activities.
The report covered a three-month period of inspection by resident inspectors and announced inspections by regional reactor inspectors. Three green findings, one of which was determined to be a non-cited violation (NCV), were identified. The significance of most findings is indicated by their color (Green, White, Yellow, Red) using Inspection Manual Chapter (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," Revision 4, dated December 2006.
NRC-Identified and Self-Revealing Findings
Cornerstone: Initiating Events
- Green.
A self-revealing finding was identified for an inadequate maintenance procedure regarding electrical connections associated with the Unit 2A Main Transformer bushings. The procedure was not clear as to the appropriate method to prepare the surface for an aluminum bushing terminal and did not provide adequate information on torque requirements and the use of anti-oxidant grease. This resulted in the failure of the bushing connection and a Unit 2 reactor scram on February 1, 2008. Exelon entered this issue into the corrective action program (CAP), performed repairs, and revised the procedure to reflect the appropriate information to successfully assemble the connection.
The issue is more that minor because it is associated with procedure quality attribute of the Initiating Events cornerstone and affected the objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during power operations. The inspectors evaluated the finding using Phase 1 of IMC 0609,
Appendix A, Significance Determination of Reactor Inspection Findings for At-Power Situations. This finding was determined to be of very low safety significance (Green) because it did not contribute to both the likelihood of a reactor trip and the likelihood that mitigation equipment or functions would be unavailable. (Section 1R12)
- Green.
Inspectors identified a Green non-cited violation (NCV) of Technical Specification (TS) 6.8.1 for failure to promptly implement actions to recover the Unit skimmer surge tank (SST) level during the 1R12 Unit 1 refueling outage. Prompt action by the operators would have prevented entrainment of the air into the residual heat removal (RHR) system, elevated radiation levels on the refuel floor, and subsequent entry into off-normal procedure ON-120, Fuel Handling Problems.
Exelon entered this issue into their CAP for resolution.
This finding is more than minor because it affects the human performance attribute of the Initiating Events cornerstone and the objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. The inspectors evaluated this finding using IMC 0609, Appendix G, Shutdown Operations Significance Determination Process,
Attachment 1. This finding is of very low safety significance (Green) because the finding did not require quantitative assessment per Checklist 7 of Attachment 1 to IMC 0609 Appendix G. The reactor time-to-boil during this event was approximately 26 hours3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br /> and adequate time was available to vent and restart the affected RHR pump in the Alternate Decay Heat Removal (ADHR) mode of operation.
Additionally, during the time that ADHR was secured, natural circulation provided reactor coolant flow. This finding has a human performance cross-cutting aspect in the area of work practices. Specifically, operators did not follow OP-AA-103-102,
Watchstanding Practices, in that they did not promptly implement actions required by the applicable alarm response procedure to recover SST level following receipt of the associated control room alarm (H.4(b)). (Section 1R20.3)
Cornerstone: Mitigating Systems
- Green.
The inspectors identified a Green finding for failure to identify corrective actions for an adverse condition associated with unsatisfactory performance of a Unit 1 main turbine bypass valve following an automatic scram event on March 22, 2008. As a result, an appropriate operability determination was not performed and the issue was not considered by the Plant Operations Review Committee during a restart meeting on March 23, 2008. Exelon entered the issue into the CAP for resolution.
The finding was more than minor because it was associated with the equipment performance attribute of the Mitigating Systems cornerstone and affected the objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The finding was assessed using Phase 1 of IMC 0609, Appendix A, Significance Determination for Reactor Inspection Findings for At-Power Situations, and determined to be of very low safety significance (Green) because the finding did not represent an actual loss of safety function of single train for greater than its TS allowed outage time. This finding has a cross-cutting aspect of Problem Identification and Resolution (PI&R) because Exelon did not thoroughly evaluate the problem such that the resolution addressed the cause of the condition or the effect the condition had on system operability (P.1(c)).
(Section 1R15)
Licensee-Identified Violations
None.
REPORT DETAILS
Summary of Plant Status
Unit 1 began the inspection period operating at full rated thermal power (RTP) and operated at full power until March 1, 2008, when the unit entered end-of-cycle coastdown operations. On February 29, 2008, operators commenced a shut down, from an initial power of 87 percent, for a planned refueling and maintenance outage (1R12). Operational Condition 5 (Refueling) was achieved on March 3, 2008. Following the completion of refueling and maintenance activities, operators commenced a reactor startup on March 19, 2008. During power ascension, Unit 1 automatically scrammed, from an initial power level of 87 percent, due to a main turbine trip on March 22, 2008. The main turbine trip was caused by an invalid main turbine/generator overspeed protection signal (power/load unbalance). The invalid signal was later determined to have originated from a faulty relay in the main generator protection system. On March 24, 2008, operators commenced a reactor startup. Full RTP was achieved on March 25, 2008.
Unit 1 remained at full RTP for the remainder of the inspection period.
Unit 2 began the inspection period operating at full RTP. On February 1, 2008, Unit 2 automatically scrammed due to a main turbine trip following a main generator lockout. A subsequent investigation determined the main generator lockout was caused by overheating of a connection between the isolated bus flexible link and the low voltage (22 kilovolt) bushing at the 2A main transformer. Following repairs and an extent-of-condition review, operators commenced a reactor startup on February 7, 2008. On February 10, 2008, with Unit 2 operating at 81 percent power, operators reduced power and secured the 2A reactor recirculation pump (RRP) due to high unidentified drywell leakage. Following maintenance on the 2A RRP and repairs to the RRP drain lines, operators commenced a reactor startup on February 12, 2008. Full RTP was achieved on February 15, 2008. Unit 2 remained at full RTP for the remainder of the inspection period.
REACTOR SAFETY
Cornerstones: Initiating Events, Mitigating Systems, and Barrier Integrity
1R01 Adverse Weather Protection
a. Inspection Scope
The inspectors evaluated Exelons preparations and protection for cold weather. On February 5, 2008, the inspectors walked down the Unit 2 Condensate Storage Tank (CST), Unit 1 Circulating Water System, Unit 1 and Unit 2 Isophase Cooling System, and Unit 1 and Unit 2 Main Turbine Lubricating Oil System to verify valve lineups and to observe system operating parameters. The inspectors verified that heat trace systems for Unit 1 and Unit 2 CSTs and the Refueling Water Storage Tank (RWST) were in operation. The inspectors observed plant conditions and evaluated those conditions against criteria documented in procedure GP-7, Cold Weather Preparation and Operation. The documents reviewed are listed in the Attachment.
b. Findings
No findings of significance were identified.
1R04 Equipment Alignment
.1 Partial Walkdown
a. Inspection Scope
The inspectors performed a partial walkdown of the plant systems listed below to verify the operability of redundant or diverse trains and components when safety-related equipment in the opposite train was either inoperable, undergoing surveillance testing, or potentially degraded. The inspectors used plant Technical Specifications (TS), Exelon operating procedures, plant piping and instrumentation drawings (P&IDs), and the Updated Final Safety Analysis Report (USFAR) as guidance for conducting partial system walkdowns. The inspectors reviewed the alignment of system valves and electrical breakers to ensure proper in-service or standby configurations as described in plant procedures and drawings. During the walkdown, the inspectors evaluated material condition and general housekeeping of the system and adjacent spaces. The documents reviewed are listed in the Attachment. The inspectors performed walkdowns of the following areas:
- Unit 1 and Unit 2 residual heat removal (RHR) systems after discovery of a pinhole water leak on the 2A RHR heat exchanger supply line;
- Unit 1 High Pressure Coolant Injection (HPCI) during maintenance on room coolers.
b. Findings
No findings of significance were identified.
.2 Complete System Walkdown
a. Inspection Scope
The inspectors conducted one complete system walkdown of the Unit 1 RHR system to verify that equipment was properly aligned. The walkdown included reviews of valve positions, major system components, electrical power availability, and equipment deficiencies. The inspectors reviewed system check off lists, system operating procedures, the system P&IDs and the UFSAR. The inspectors reviewed outstanding maintenance activities and issue reports (IRs) associated with the Unit 1 RHR system to determine if they would adversely affect system operability. The walkdown also included an evaluation of system piping, supports, and component foundations to ensure they were not degraded. The documents reviewed are listed in the Attachment.
b. Findings
No findings of significance were identified.
1R05 Fire Protection
Fire Protection - Tours (71111.05Q - 5 samples)
a. Inspection Scope
The inspectors conducted a tour of the five areas listed below to assess the material condition and operational status of fire protection features. The inspectors verified that combustibles and ignition sources were controlled in accordance with Exelons administrative procedures, fire detection and suppression equipment was available for use, and that passive fire barriers were maintained in good material condition. The inspectors also verified that station personnel implemented compensatory measures for out-of-service, degraded, or inoperable fire protection equipment in accordance with the stations fire plan. The documents reviewed are listed in the Attachment. The inspectors toured the following areas:
- Unit 1 RHR Heat Exchanger and Pump Rooms;
- Unit 1 B and D RHR Heat Exchanger and Pump Rooms;
- D22 Diesel Generator Room and Fuel Oil/Lubricating Oil Tank;
- Unit 2 B Core Spray Room; and
- Unit 1 Drywell.
b. Findings
No findings of significance were identified.
1R08 In-Service Inspection
a. Inspection Scope
Activities inspected during the Unit 1 refueling outage (1R12) included observations of ultrasonic testing (UT) in progress and analysis of test results using both manual UT techniques and a vendor-based computer UT system. This included the areas of the inner radius of the reactor vessel shell-to-nozzle N17B, Zone 2A; the 2" diameter pipe to elbow weld RW118; the dissimilar metal (DM) nozzle to safe end welds DCA-319-1 N5A and DCA-320-1 N5B in the core spray system; and the main steam pipe to isolation valve weld MSA 023R located outside of the containment wall. The inspector also reviewed a sample of in-vessel visual inspection (IVVI) video records for jet pump components and the steam dryer. The inspector reviewed test data for several ultrasonic and visually-identified indications and confirmed that Exelon evaluated the data as part of the in-service inspection process.
The inspector reviewed the results of radiographic testing (RT) dated February 8, 2008, for circumferential pipe welds SW1 and SW2 in the Unit 1 reactor core isolation cooling (RCIC) system as performed per the RT procedure 94-RT-011, Revision 6. The inspector reviewed the radiographs and RT documentation for comparison to the American Society of Mechanical Engineers (ASME) Code fabrication requirements. The inspector also noted the sensitivity of the radiographic method as shown by the penetrameter and densitometer measurement, the identification of the radiographer, and acceptance by the RT data reviewers.
Inspection included review of Engineering Change Request (ECR) LG-07-00381-004 for the repair of thinned RHRSW system pipe wall documented in IR 508152. The inspector verified that the repairs, by weld overlay of areas of the >B= RHRSW Return Header, met Regulatory Guide 1.147 and the ASME Code Cases N-513-1 and N-661. The inspector reviewed mock-up repair procedures and verified the welding procedure and the welder qualifications met the requirements of the ASME Code. The inspector observed several of the completed weld overlay repairs to verify compliance with the ASME Code.
The inspector compared Exelon=s DM Weld program with the Electric Power Research Institute (EPRI) Boiling Water Reactor Vessel and Internals Project letter 2007-367 (BWRVIP-2007-367), Recommendations Regarding Dissimilar Metal Weld Examinations, and BWRVIP-75A, Technical Basis for Revisions to NRC Generic Letter (GL) 88-01 Inspection Schedules. The inspector reviewed the data of previous and current (1R12) automated ultrasonic examination of the safe end to nozzle welds N5A and N5B, DCA-319-1 and DCA-320-1, for the disposition of recordable indications.
While no UT indications from previous outages required re-examination during 1R12, the inspector reviewed the condition of N2H, a safe end to nozzle weld, as determined in the 2004 refuel outage, and the basis for the re-examination scheduled during the 1R13 outage. The inspector walked down portions of the drywell and external portions of the containment boundary with one of the site visual examiners to confirm the acceptance of a sample of the visual examinations made per procedures MAG-CG-425, Visual Examination of Containment Vessels and Internals, Revision 4, and procedure ER-AA-335-018, Visual Examination of ASME Class MC and CC Containment Surfaces and Components, Revision 5.
The inspectors reviewed the extent of oversight of in-service inspection (ISI) and non-destructive examination activities, including the topics of current ISI oversight and surveillance. The inspector reviewed a sample of IRs to confirm that identified problems were being documented for evaluation and proper resolution. The documents reviewed are listed in the Attachment.
b. Findings
No findings of significance were identified.
1R11 Licensed Operator Requalification Program -
a. Inspection Scope
On January 22, 2008, the inspectors observed the administration of as-found evaluated licensed operator requalification simulator scenarios. The same scenario was administered twice to different crews. The scenario included a simulated reactor pressure instrument failure, a small drywell leak, a full power anticipated-transient-without-a-scram (ATWS), and a Group 1 containment isolation. The inspectors observed the performance of both operating crews responding to the simulator scenarios. The inspectors assessed licensed operator performance, including operating critical tasks that measure operator actions required to ensure the safe operation of the reactor and protection of the nuclear fuel and primary containment barriers. The inspectors observed the training evaluators critiques at the conclusion of each scenario.
The documents reviewed are listed in the Attachment.
b. Findings
No findings of significance were identified.
1R12 Maintenance Effectiveness
a. Inspection Scope
The inspectors evaluated Exelons work practices and follow-up corrective actions for structures, systems, and components (SSCs) and identified issues to assess the effectiveness of Exelons maintenance activities. The inspectors reviewed the performance history of risk significant SSCs and assessed Exelons extent-of-condition determinations for those issues with potential common cause or generic implications to evaluate the adequacy of the stations corrective actions. The inspectors assessed Exelons problem identification and resolution actions for these issues to evaluate whether Exelon had appropriately monitored, evaluated, and dispositioned the issues in accordance with Exelon procedures and the requirements of 10 CFR 50.65, Requirements for Monitoring the Effectiveness of Maintenance. In addition, the inspectors reviewed selected SSC classifications, performance criteria and goals, and Exelons corrective actions that were taken or planned, to evaluate whether the actions were reasonable and appropriate. The documents reviewed are listed in the
. The inspectors performed the following sample:
b. Findings
Introduction:
The inspectors identified a Green, self-revealing finding for an inadequate maintenance procedure regarding electrical connections associated with the Unit 2A Main Transformer.
Description:
On February 1, 2008, with Unit 2 at 100 percent power, Unit 2 automatically scrammed due to an automatic main turbine trip following a generator lockout. The cause of the generator lockout was an isolated-phase bus ground fault on the 2A Main Transformer. The ground fault was caused by overheating of the phase connection between the isolated-phase bus flexible link and the low voltage bushing.
The 2A Main Transformer bushings were replaced in March 2007 when the transformer was exchanged with a spare. Investigation revealed that the cause of the overheated flexible link was due to an inadequate maintenance procedure. A similar event had occurred in May 2000 when Unit 1 automatically scrammed due to a main transformer phase-to-phase fault. Prior to 2001, transformer maintenance was performed by Exelon Energy Delivery (EED). As a result of the 2000 automatic scram, maintenance procedure M-035-003, X101 Oil Cooled Transformers Cleaning, Examination, and Testing was created for EED as a guide to properly assemble bolted connections. The procedure combined EED drawings and previous maintenance procedures to create a station specific procedure. In 2001, maintenance ownership of the transformers was transferred to the Limerick Generating Station. Following the transition of transformer maintenance responsibility, the maintenance procedure was revised such that technical information pertaining to the use of anti-oxidant grease, surface preparation, and bolt torque requirements had been moved, omitted, or lost clarity in the procedure. Exelon determined that the procedure was not clear on how to properly prepare an aluminum bushing terminal and had omitted the use of anti-oxidant grease on the connection to protect the aluminum bushing flange from oxidation. Also, the procedure did not specify torque requirements for bolted connections with Belleville washers.
The performance deficiency associated with this event was an inadequate maintenance procedure for performing electrical connections on the Unit 2A Main Transformer bushings. The procedure used was insufficient to ensure proper connection of the bushings. The procedure was not clear as to the appropriate method to prepare the surface for an aluminum bushing terminal and did not provide adequate information on torque requirements and the use of anti-oxidant grease. This resulted in a Unit 2 reactor scram on February 1, 2008. Exelon entered this issue into the corrective action program as IR 730021. Exelon performed repairs and revised the procedure to reflect the appropriate information to successfully assemble the connection.
Analysis:
The issue is more that minor because it is associated with the procedure quality attribute of the Initiating Events cornerstone and affected the objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions during power operations. The inspectors evaluated the finding using Phase 1 of IMC 0609, Appendix A, Significance Determination of Reactor Inspection Findings for At-Power Situations. This finding was determined to be of very low safety significance (Green) because it did not contribute to both the likelihood of a reactor trip and the likelihood that mitigation equipment or functions would be unavailable.
This finding does not have a cross-cutting aspect because it is not reflective of current station performance. The procedure used to perform the maintenance was created in January 2001.
Enforcement:
Enforcement action does not apply because the performance deficiency did not involve a violation of regulatory requirements. Specifically, the performance deficiency involved the 2A main transformer, a non-safety related component. However, failure of the 2A main transformer due to an inadequate maintenance procedure was considered a finding and was entered in to the CAP as IR 730021. (FIN 05000353/2008002-01, Inadequate Maintenance Procedure for the 2A Main Transformer)
1R13 Maintenance Risk Assessments and Emergent Work Control
a. Inspection Scope
The inspectors evaluated the effectiveness of Exelons maintenance risk assessments required by 10 CFR 50.65(a)(4). This inspection included discussion with control room operators and risk analysis personnel regarding the use of Exelons on-line risk monitoring software. The inspectors reviewed equipment tracking documentation, daily work schedules, and performed plant tours to gain assurance that the actual plant configuration matched the assessed configuration. Additionally, the inspectors verified that Exelons risk management actions, for both planned and emergent work, were consistent with those described in Exelon procedure, ER-AA-600-1042, On-Line Risk Management. The documents reviewed are listed in the Attachment. Inspectors reviewed the following samples:
- D23 Diesel Generator Overvoltage, IR 721408;
- Emergent Maintenance on B Control Room Emergency Fresh Air Supply (CREFAS)with the A Standby Gas Treatment (SBGT) System Out-of-Service for Planned Maintenance, IR 725441;
- D23 Emergency Diesel Generator (EDG) Jacket Water Cooling Pump Contactor Replacement, IR 737389; and
b. Findings
No findings of significance were identified.
1R15 Operability Evaluations
a. Inspection Scope
For the five operability evaluations described below, the inspectors assessed the technical adequacy of the evaluations to ensure that Exelon properly justified TS operability and verified that the subject component or system remained available such that no unrecognized increase in risk occurred. The inspectors reviewed the UFSAR to verify that the system or component remained available to perform its intended safety function. In addition, the inspectors reviewed compensatory measures implemented to ensure that the measures worked and were adequately controlled. The inspectors also reviewed a sample of issue reports to verify that Exelon identified and corrected deficiencies associated with operability evaluations. The documents reviewed are listed in the Attachment. The inspectors performed the following assessments:
- 1A RHR Unit Cooler Flowrate Difference, IR 681355;
- Division 1 Redundant Reactivity Control System (RRCS) Alarms Received in the Main Control Room, IR 718479;
- D14 Diesel Generator Lubricating Oil Flashpoint Decline, IR 736831;
- Unit 1 HPCI Oil Filter Clogging due to Corrosion Products, IR 744446; and
- Unit 1 Main Turbine Bypass Valve Number 4 Operation Following Turbine Trip and Reactor Scram, IR 753365.
b. Findings
Introduction.
The inspectors identified a Green finding for failure to identify corrective actions for unsatisfactory performance of a main turbine bypass valve following the March 22, 2008, Unit 1 scram.
Description.
During the performance of GP-18, Scram/ATWS Event Review, following the Unit 1 turbine trip and reactor scram on March 22, 2008, Exelon identified unsatisfactory performance of the main turbine bypass system. Specifically, the number four bypass valve opened sequentially out-of-order (i.e., after bypass valves number five and number six) following the main turbine trip. Engineering personnel identified this adverse condition while performing GP-18, Attachment 8, Engineering Event Investigation. Per procedure, Exelon entered the issue in the CAP as IR 753365.
The inspectors reviewed IR 753365 and identified that the Station Oversight Committee closed this IR to IR 753306. Further review of IR 753306, which was written to address the cause of the scram, showed that Exelon did not address the adverse condition associated with the number four bypass valve opening sequentially out-of-order. The inspectors questioned the appropriateness of not evaluating the number 4 bypass valve condition prior to plant restart which occurred on March 24, 2008. The inspectors also noted that the condition was not reviewed during the Plant Operations Review Committee plant restart meeting which occurred on March 23, 2008, as expected.
Exelon entered this issue into the CAP as IR 754571. On March 26, 2008, Operations declared the number four bypass valve inoperable per TS 3.7.8, Main Turbine Bypass System, due to its demonstrated performance following the main turbine trip on March 22, 2008.
The performance deficiency associated with this event is the failure to identify corrective actions for unsatisfactory performance of the Unit 1 number four main turbine bypass valve following an automatic scram event on March 22, 2008, as identified in IR 753365.
Analysis.
The finding was more than minor because it was associated with the equipment performance attribute of the Mitigating Systems cornerstone and affected the objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The inspector assessed the finding using Phase 1 of IMC 0609, Appendix A, Significance Determination Process for Reactor Inspection Findings for At-Power Situations and determined the finding to be of very low safety significance (Green) because the finding did not represent an actual loss of safety function of a single train for greater than its TS allowed outage time.
This finding has a cross-cutting aspect of Problem Identification and Resolution because Exelon did not thoroughly evaluate the problem such that the resolution addressed the cause and did not evaluate the effect the adverse condition had on system operability (P.1(c)). This finding is discussed in Exelons CAP as IR 754571.
Enforcement.
Enforcement action does not apply because the performance deficiency did not involve a violation of regulatory requirements. Specifically, the performance deficiency involved the main turbine bypass valve system which is not safety-related.
However, failure to correct the unsatisfactory performance of the number four turbine bypass valve following the March 22, 2008, Unit 1 scram was considered a finding. This issue was entered in to the CAP as IR 754571. (FIN 05000352/2008002-02, Failure to Correct Main Turbine Bypass Valve Adverse Condition.)
1R18 Plant Modifications
a. Inspection Scope
The inspectors reviewed the plant modification listed below to ensure that installation of the modification did not adversely affect systems important to safety. The inspectors compared the modification with the UFSAR and TS to verify that the modification did not affect system operability or availability. The inspectors ensured that station personnel implemented the modification in accordance with the applicable temporary configuration change process. The inspectors also reviewed the impact on existing procedures to verify Exelon made appropriate revisions to reflect the temporary configuration change.
The documents reviewed are listed in the Attachment. The inspectors reviewed the following:
- LG 08-00055, 2A Recirculation Drain Line Modification.
b. Findings
No findings of significance were identified.
1R19 Post-Maintenance Testing
a. Inspection Scope
The inspectors reviewed the six post-maintenance tests (PMTs) listed below to verify that procedures and test activities ensured system operability and functional capability.
The inspectors reviewed Exelons test procedures to verify that the procedures adequately tested the safety functions that may have been affected by the maintenance activity, and that the acceptance criteria in the procedures were consistent with information in the licensing and design basis documents. The inspectors also witnessed the test or reviewed test data to verify that the results adequately demonstrated restoration of the affected safety functions. The documents reviewed are listed in the
. The inspectors performed the following samples:
- D23 EDG governor tuning response time test following planned system maintenance;
- 2C-V512/2G-V210 vent fan relay repairs;
- ST-4-LLR-051-1 following repairs to MSIV 1F028C due to failed local leak rate testing;
- Unit 1 main generator protection relay replacements; and
- Post maintenance testing following D14 EDG K1 relay repairs.
b. Findings
No findings of significance were identified.
1R20 Refueling and Other Outage Activities
.1 Unit 2 Automatic Reactor Scram
a. Inspection Scope
The inspectors evaluated the activities associated with the forced outage that occurred as a result of a Unit 2 automatic reactor scram (2F40) on February 1, 2008. A phase-to-ground fault on the 2A main transformer actuated the main generator neutral overvoltage relay which tripped the generator protection lockout relays and resulted in a main turbine trip and subsequent automatic reactor scram. The documents reviewed are listed in the
. From February 1 through February 8, 2008, the inspectors monitored the activities listed below:
- Limericks forced outage plan, including appropriate consideration of risk, industry experience, and previous site-specific problems;
- Plant Operations Review Committee and Outage Control Center meetings;
- 2A main transformer troubleshooting and repair activities;
- Repairs to the 2B RRP seal;
- Unit 2 drywell initial tour and closeout inspection; and
- Portions of the reactor startup and ascension to full-power operation.
b. Findings
No findings of significance were identified.
.2 Unit 2 Manual Shutdown Due to High Drywell Leakage
a. Inspection Scope
The inspectors reviewed the stations work schedule for the Unit 2 manual shutdown and forced outage (2F41) due to high drywell leakage which was conducted February 10 through February 13, 2008. The inspectors reviewed Exelons development and implementation of outage plans and schedules to verify that risk, industry experience, previous site-specific problems, and defense-in-depth were considered. During the outage, the inspectors observed the transfer of Unit 2 to single recirculation loop operations, portions of the shutdown and cooldown processes, and monitored Exelons controls associated with the following outage activities:
- Configuration management, including maintenance of defense-in-depth, commensurate with the forced outage plan for key safety functions and compliance with the applicable TS when taking equipment out of service;
- Implementation of clearance activities and confirmation that tags were properly hung and that equipment was appropriately configured to safely support the associated work or testing;
- Monitoring of decay heat removal operations;
- Unit 2 drywell initial inspection; and
- Portions of reactor startup and ascension to full-power operation.
b. Findings
No findings of significance were identified
.3 Unit 1 Maintenance and Refueling Outage
a. Inspection Scope
The inspectors reviewed the stations work schedule and outage risk plan for the Limerick Unit 1 maintenance and refueling outage (1R12), which was conducted March 1 through March 20, 2008. The inspectors reviewed Exelons development and implementation of outage plans and schedules to verify that risk, industry experience, previous site-specific problems, and defense-in-depth were considered. During the outage, the inspectors observed portions of the shutdown and cooldown processes and monitored Exelon controls associated with the following outage activities:
- Configuration management, including maintenance of defense-in-depth, commensurate with the outage plan for the key safety functions and compliance with the applicable TS when taking equipment out of service;
- Implementation of clearance activities and confirmation that tags were properly hung and that equipment was appropriately configured to safely support the associated work or testing;
- Installation and configuration of reactor coolant pressure, level, and temperature instruments to provide accurate indication and instrument error accounting;
- Status and configuration of electrical systems and switchyard activities to ensure that TS were met;
- Monitoring of decay heat removal operations;
- Impact of outage work on the ability of the operators to operate the spent fuel pool cooling system;
- Reactor water inventory controls, including flow paths, configurations, alternative means for inventory additions, and controls to prevent inventory loss;
- Activities that could affect reactivity;
- Maintenance of secondary containment as required by TS;
- Refueling activities, including fuel handling and fuel receipt inspections;
- Startup and ascension to full power operation, tracking of startup prerequisites, and walkdown of the drywell (primary containment) to verify that debris had not been left which could block emergency core cooling system suction strainers; and
- Identification and resolution of problems related to refueling outage activities.
b. Findings
Introduction:
The inspectors identified a Green, non-cited violation of TS 6.8.1, Procedures and Programs, in that Limerick did not implement prompt actions to recover level in the skimmer surge tank (SST) which resulted in elevated radiation levels on the refueling floor and entrainment of air in the Unit 1B RHR pump.
Description:
At 10:55 p.m. on March 9, 2008, with Unit 1 shutdown in a refueling outage, the refueling bridge area radiation monitor alarmed and personnel on the refueling floor noticed several air bubbles in the reactor cavity. Operations personnel entered off-normal procedure ON-120, Fuel Handling Problems, and evacuated the refuel floor. At 11:15 p.m., operators secured the 1B RHR pump to terminate air entrainment and established condensate transfer make-up to the reactor cavity through the 1D low pressure coolant injection system (LPCI) in order to recover level in the SST.
During this event, the 1B RHR pump was operating in the alternate decay heat removal (ADHR) line-up. ADHR is a method of decay heat removal in which the RHR pump draws water from the SST, which is connected to the reactor cavity via a weir gate, then discharges the water through the RHR heat exchanger and back to the reactor cavity.
Operators normally maintain sufficient water level in the SST by controlling the amount of water added to and discharged from the reactor cavity. During ADHR operation, water level in the SST is typically maintained at greater than 20 feet.
At approximately 6:30 p.m., water level in the SST lowered to less than 20 feet and continued to slowly lower until operators secured the 1B RHR pump at 11:15 p.m.
Though the operators logged the Fuel Pool Cooling and Clean-up System Trouble Alarm at 10:50 p.m., the inspectors determined, based on plots of SST level over time, that the alarm actually should have annunciated at approximately 9:45 p.m. Further discussions with Exelon operations personnel confirmed that operators did receive the alarm at around 9:45 p.m., but believed that it was caused by activities associated with the ongoing D11 EDG surveillance testing. As a result, the operators did not immediately inform the control room supervisor and did not promptly implement the actions required per the alarm response card (ARC). The inspectors noted that procedure OP-AA-103-102, Watchstanding Practices, directs operators to aggressively investigate alarms to fully understand the reason for the alarm and review and perform the ARC for all unexpected alarms. At around 10:20 p.m., the main control room operators dispatched an equipment operator to the local panel to verify SST level and at 10:29 p.m., the operators reduced cavity discharge flowrate by 10 gallons per minute.
The performance deficiency associated with this event is failure to promptly implement actions described in the ARCs to recover level in the SST. ARC-MCR-112 J5, Fuel Pool Cooling and Clean-up System Trouble, directs the main control room operators to dispatch an operator to the local alarm panel and implement actions required by the respective local panel ARC. ARC-BOP-10C222 B4, Skimmer Surge Tank Low Level, instructs operators to restore water level in the SST. Operator response to the lowering SST level and Fuel Pool Cooling and Clean-up System Trouble alarm was considered untimely in two respects. First, lowering SST trends were available for monitoring and operator action for a period of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and 25 minutes before the air entrainment event.
Secondly, one hour and 10 minutes passed between receipt of the control room alarm and 10:55 p.m., sufficient time for the operators to have responded to the condition and prevented the event.
Analysis:
The finding is more than minor because it affects the human performance attribute of the Initiating Events cornerstone and the objective of limiting the likelihood of those events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Prompt action by the operators would have prevented entrainment of air into the RHR system, elevated radiation levels on the refuel floor, and subsequent entry into procedure ON-120, Fuel Handling Problems. The inspectors evaluated this finding using Attachment 1 of IMC 0609, Appendix G, Shutdown Operations Significance Determination Process. This finding is of very low safety significance because the finding did not represent a loss of control and did not require quantitative assessment per Checklist 7 of Attachment 1 to IMC 0609, Appendix G. Specifically, the reactor time-to-boil during this event was approximately 26 hours3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br />, time to core uncover was greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and adequate time was available to vent and restart the affected RHR pump in the ADHR mode of operation. Additionally, during the time that ADHR was secured, natural circulation provided reactor coolant flow.
This issue has a human performance cross-cutting aspect in the area of work practices.
Operators did not follow OP-AA-103-102, Watchstanding Practices, and thus did not promptly implement actions required by the applicable alarm response procedure to recover SST level (H.4(b)).
Enforcement:
Technical Specification 6.8.1, Procedures and Programs, states, in part, that written procedures shall be established, implemented, and maintained covering the applicable procedures as recommended in NRC Regulatory Guide 1.33, Quality Assurance Program Requirements (Operation), Appendix A, February 1978.
Regulatory Guide 1.33, Appendix A, Section 5.0, requires procedures for abnormal, off-normal, or alarm conditions. ARC-BOP-10C2222 B4, Skimmer Surge Tank Low Level, instructed the operators to restore level in the SST. Contrary to this requirement, on March 9, 2008, operators did not promptly implement actions to recover level in the SST for one hour and 10 minutes following receipt of the associated control room alarm. The delay in implementation of actions resulted in elevated radiation levels on the refuel floor and entrainment of air in the 1B RHR system which had the potential to cause a loss of ADHR. Because this finding is of very low safety significance and Exelon has entered this issue into their corrective action program (IR 747235), this violation is being treated as a non-cited violation consistent with Section VI.A of the NRC Enforcement Policy.
(NCV 05000352/2008002-03, Failure to Promptly Implement Actions for a Low SST Level)
.4 Unit 1 Automatic Reactor Scram
a. Inspection Scope
The inspectors evaluated the activities associated with the forced outage that occurred as a result of a Unit 1 automatic reactor scram (1F43) on March 22, 2008. An invalid main turbine/generator overspeed protection signal (power/load unbalance) actuated which resulted in a main turbine trip and subsequent reactor scram. The invalid signal was later determined to be caused by a faulty relay in the main generator protection system. The documents reviewed are listed in the Attachment. From March 22 through March 25, 2008, the inspectors monitored the following activities:
- Limericks forced outage plan, including consideration of risk, industry experience, and previous site-specific problems;
- Plant Operations Review Committee and Outage Control Center meetings;
- Electrohydraulic control (EHC) system troubleshooting; and
- Portions of the reactor startup and ascension to full-power operation.
b. Findings
No findings of significance identified.
1R22 Surveillance Testing
a. Inspection Scope
The inspectors witnessed the performance and reviewed test data for five surveillance tests (STs) that are associated with risk-significant SSCs. The review verified that Exelon personnel followed TS requirements and that acceptance criteria were appropriate. The inspectors also verified that the station established proper test conditions, as specified in the procedures, that no equipment preconditioning activities occurred, and that acceptance criteria had been met. The documents reviewed are listed in the Attachment. The inspectors reviewed STs for the following systems and components:
- ST-6-092-322-2, D22 Diesel Generator Loss of Coolant Accident/Load Reject Testing and Fast Start Operability Test Run;
- ST-4-051-311-2, A RHR Auto Close S/I Contact;
- ST-6-051-231-2, A RHR Pump, Valve, and Flow Test;
- ST-6-107-640-1, Reactor Vessel Temperature and Pressure Monitoring; and
- ST-4-LLR-051-1, Main Steam Line C Local Leak Rate Testing.
b. Findings
No findings of significance were identified.
RADIATION SAFETY
Cornerstone: Occupational Radiation Safety
2OS1 Access Control to Radiologically Significant Areas (71121.01 - 22 samples)
a. Inspection Scope
During the periods of January 7 - 11, 2008, and March 10 -14, 2008, the inspector conducted the following activities to verify that Exelon implemented physical, administrative, and engineering controls for access to locked high radiation areas (LHRAs) and other radiologically controlled areas (RCAs), and that workers were adhering to these controls when working in these areas during power operations and during the Unit 1 refueling outage (1R12). The inspector reviewed implementation of these controls against the criteria contained in 10 CFR 20, TSs, applicable industry standards, and Exelon procedures. This inspection activity represents completion of 22 samples relative to this inspection area. The documents reviewed are listed in the
.
Plant Walkdown and RWP Reviews
- The inspector identified exposure significant work areas in Units 1 and 2, including the refuel floor and areas of the Reactor Buildings, Control Structure, Radwaste Building, and Turbine Buildings. The inspector reviewed survey maps and radiation work permits (RWP) for these areas to determine if associated controls were acceptable.
- During the 1R12 refueling outage, the inspector identified exposure significant work areas in the Unit 1 drywell, refuel floor, and reactor building. Specific work activities included: replacement of the RHR 50B valve, phase II fuel shuffle, in-vessel visual inspection (IVVI), and Emergency Service Water (ESW) pipe replacement. The inspector reviewed radiation survey maps and RWP associated with these areas to determine if the associated controls were acceptable. RWPs reviewed included; LG-0-08-00092/93, Remove/Replace 50B Valve: LG-0-08-00060/69, Fuel Floor Outage Middle Activities; and LG-0-08-0013, ESW Header Pipe Replacement.
- The inspector toured accessible RCAs in the reactor building, radwaste building, and turbine building, for both units. Additionally, the inspector toured the Unit 1 drywell and refueling floor during the March refueling outage. While accompanied by a radiation protection technician, the inspectors performed independent radiation surveys of selected areas to confirm the accuracy of survey maps and the adequacy of postings.
- In evaluating RWPs, the inspector reviewed electronic dosimeter dose/dose rate alarm setpoints to determine if the setpoints were consistent with the survey indications and plant policy. Work activities reviewed in January included installation of scaffolding and temporary shielding in the Unit 1 A and B RHR pump rooms to support ESW modifications, and decontaminating a reactor cavity work platform.
Work activities reviewed during the Unit 1 outage included removal/replacement of the 50B valve (RWP LG-0-08-00092), installation/removal of drywell scaffolding (RWP LG-0-08-00081), and Refuel Floor Outage Middle Activities (RWP LG-0-08-00060).
- The inspector examined the airborne monitoring instrumentation and engineering controls for potential airborne radioactivity areas. The inspector performed plant tours to confirm that the airborne sampling equipment was operating and calibrated.
- The inspector reviewed RWPs and associated instrumentation and engineering controls for potential airborne radioactivity areas located in the Unit 1 drywell, reactor building, and refuel floor. The inspector reviewed dose assessment records related to evaluating airborne radioactivity concentrations and personnel contaminations to confirm that no worker received an internal dose in excess of 10 mrem when performing outage related tasks. The inspector reviewed the dose assessment methodology for internal exposures that were less than 10 mrem to confirm the accuracy of the results.
- The inspector determined that during 2007, there were no internal exposures that exceeded 50 mrem Committed Effective Dose Equivalent (CEDE). The inspector also reviewed data for the ten highest exposed individuals for 2007 and the dose/dose rate alarm reports, and determined that no exposure exceeded site administrative, regulatory, or performance indicator criteria. Additionally, the inspector reviewed the dosimetry records and associated documentation for declared pregnant workers to determine if dose was controlled in accordance with 10 CFR 20.1208.
Problem Identification and Resolution
- In January 2008, the inspector reviewed elements of the Exelons CAP related to controlling access to RCAs, completed since the last inspection of this area, to determine if problems were being entered into the program for resolution. The inspector reviewed 17 IRs, recent station ALARA committee meeting minutes, Common Cause Analysis Reports, a Nuclear Oversight Audit, and Nuclear Oversight Objective Evidence (field observation) Reports for 2007 relating to controlling activities in RCAs to evaluate Exelons threshold for identifying, evaluating, and resolving occupational radiation safety problems. The review included a check of possible repetitive issues such as radiation worker and radiation protection technician errors.
- Between January 1, 2008 and March 14, 2008, the inspector reviewed 27 IRs associated with radiation protection control access. The inspector discussed these IRs with Exelon staff to determine if the follow up activities were being conducted in an effective and timely manner, commensurate with their safety significance.
- The inspector reviewed Exelons actions taken in response to identifying elevated dose rates on the refueling bridge as identified in IR 747235 (see Section 1R20.3 of this report for further details). As part of this review, the inspector confirmed that workers evacuated the area in response to an area monitor alarm, air samples were taken and evaluated, contamination surveys were performed, and an action plan was developed to reduce source term concentrations in the reactor cavity. Additionally, the inspector attended an inter-departmental meeting in the Outage Control Center where source mitigation strategies and dose control measures were developed.
Jobs-In-Progress Review
- The inspector observed aspects of various maintenance activities being performed during the inspection period to verify that radiological controls, such as required surveys, area postings, job coverage, locked high radiation area controls, and pre-job high radiation area (HRA) briefings were conducted. The inspector observed activities to confirm that personnel dosimetry was properly worn, and workers were knowledgeable of work area radiological conditions. Tasks observed included scaffolding/temporary shielding installation in the Unit 1 A and B RHR pump rooms, and decontaminating a reactor cavity work platform. The inspector attended the pre-job briefings for these jobs to assess the adequacy of information presented and the interdepartmental coordination required in completing these tasks.
High Risk Significant, High Dose Rate HRA, and Very High Radiation Area Controls
- The inspector discussed high dose rate (HDR) areas and Very High Radiation Area (VHRA) areas controls and procedures with a radiation protection supervisor. The inspector reviewed Exelon procedures to verify that procedure changes did not substantially reduce the effectiveness and level of worker protection.
- In January 2008, the inspector inventoried keys to Unit 1 and Unit 2 locked high radiation areas (LHRAs) and VHRAs, maintained by the radiation protection department and operations department. During plant tours, the inspector inspected 98 TS LHRAs to ensure they were properly secured and posted. Additionally, during the Unit 1 refueling outage, the inspector inspected accessible LHRAs in the Unit 1 drywell to ensure they were properly secured and posted.
- The inspector reviewed procedures for controlling access to HRAs and VHRAs to determine if the administrative and physical controls were adequate. The inspector also reviewed the physical and procedural controls for securing and removing highly contaminated/activated materials stored in the spent fuel pool. The inspector discussed the adequacy of current access controls with Radiation Protection Management, including prerequisite communications and authorizations, to verify that procedure changes did not substantially reduce the effectiveness and level of worker protection.
Radiation Worker/Radiation Protection Technician Performance
- The inspector assessed radiation worker and radiation protection technician performance by attending pre-job briefings for various jobs-in-progress, attending morning departmental meetings, and observing in-plant/control point activities.
Through interviews and task observations, the inspector evaluated job preparations, the degree of technician coverage for work performed in the HRAs, and the knowledge level of the workers for specific tasks.
- The inspector observed and questioned radiation workers and radiation protection technicians while conducting various outage tasks, including removal/replacement of the RHR 50B valve, various refuel floor activities, and drywell radiography tasks.
- The inspector reviewed IRs related to radiation worker and radiation protection technician errors, and personnel contamination event reports to determine if an observable pattern traceable to a similar cause was evident.
b. Findings
No findings of significance were identified.
.2 ALARA Planning and Controls
a. Inspection Scope
During the period March 10 - 14, 2008, the inspector conducted the following activities to verify that Exelon implemented operational, engineering, and administrative controls to maintain personnel exposure as-low-as-is-reasonably-achievable (ALARA) for tasks conducted during the Unit 1 refueling outage (1R12). Implementation of these controls was reviewed against the criteria contained in 10 CFR 20, applicable industry standards, and Exelon procedures. This inspection represents completion of nine samples relative to this inspection area. The documents reviewed are listed in the Attachment.
Radiological Work Planning
- The inspector reviewed information regarding outage exposure history, current exposure trends, and ongoing activities to assess current performance and outage exposure challenges. The inspector determined the sites three-year rolling collective average exposure.
- The inspector reviewed the 1R12 outage work scheduled during the outage period and the associated work activity dose estimates and ALARA Plans (AP). Scheduled work included the removal/replacement of the RHR 50B valve (AP 2008-024), the ESW header pipe replacement (AP 2008-005), snubber inspections (AP2008-019),
DW shielding installation (AP2008-026), DW scaffolding removal (AP 2008-09),control rod drive exchange (AP2008-003), in-core instrument change-out (AP 2008-016), and various activities on the reactor cavity work platform (RCWP) (AP 2008-030).
- The inspector evaluated the departmental interfaces between radiation protection, operations, maintenance crafts, and engineering to identify missing ALARA program elements and interface problems. The inspector accomplished the evaluation by attending a daily work scheduling/status meeting in the Outage Control Center and a Station ALARA Committee meeting, reviewing recent Station ALARA Council meeting minutes, work-in-progress ALARA reviews, and Nuclear Oversight Objective Evidence Reports, and interviewing the site Radiation Protection Manager.
- The inspector also reviewed the status of long term projects, designed to reduce personnel exposure, as contained in 2006-2011, Exposure Reduction Plan.
Verification of Dose Estimates
- The inspector reviewed the assumptions and basis for the annual (2008) site collective exposure projections for the 1R12 outage and for routine power operations.
- The inspector reviewed Exelons procedures associated with monitoring and re-evaluating dose estimates when the forecasted cumulative exposure for tasks differed from the actual exposure received. The inspector reviewed the dose/dose rate alarm reports, work-in-progress evaluations, and exposure data for selected individuals receiving the highest Total Effective Dose Equivalent (TEDE) for 2008 to confirm that no individual exposure exceeded the regulatory limit, or met the performance indicator reporting guideline. Included in this review were the actions taken to control dose on the RCWP, following the identification of elevated cavity dose rates.
Jobs-In-Progress
- The inspector observed various 1R12 jobs-in-progress to evaluate the effectiveness of dose control measures. Jobs observed included removal/replacement of the RHR 50B valve, DW scaffolding disassembly, the 50B radiography, RCWP activities, fuel shuffle, and ESW piping replacement. As part of this evaluation, the inspector reviewed the RWP, survey maps, shielding effectiveness, and contamination control measures. The inspector attended the pre-job briefing for radiographic examinations to be performed on the newly installed RHR 50B valve to determine if affected areas were properly controlled.
Source Term Reduction and Control
- The inspector reviewed the status and historical trends for the Unit 1 source term.
By reviewing survey maps and interviewing the Radiation Protection Manager, the inspector evaluated the recent source term measurements and control strategies.
Specific strategies employed by Exelon included performing a reactor soft shutdown, system flushes, installation of permanent and temporary shielding in the drywell, vacuuming the seal plate, hydrolazing of reactor nozzles, and increasing the capacity of the reactor cavity filtration system.
Declared Pregnant Workers
- The inspector reviewed the radiological controls and dosimetry records for one declared pregnant worker to determine if procedural exposure controls were properly implemented.
Problem Identification and Resolution
- The inspector reviewed elements of Exelons corrective action program related to implementing ALARA program controls, including IRs, Nuclear Oversight Objective Evidence reports, and Station ALARA Committee meeting minutes to determine if problems were being entered at a conservative threshold and resolved in a timely manner.
b. Findings
No findings of significance were identified.
OTHER ACTIVITIES
4OA1 Performance Indicator (PI) Verification
a. Inspection Scope
The inspectors sampled Exelons submittal of the initiating events and mitigating systems performance indicators listed below to verify the accuracy of the data recorded from the fourth quarter of 2007 through the first quarter of 2008. The inspectors utilized performance indicator definitions and guidance contained in Nuclear Energy Institute (NEI) 99-02, Regulatory Assessment Performance Indicator Guideline, Revision 5, to verify the basis in reporting for each data element. The inspectors reviewed various documents, including portions of the main control room logs, issue reports, power history curves, work orders, and system deviation reports. The inspectors also discussed the method for compiling and reporting performance indicators with cognizant engineering personnel and compared graphical representations from the most recent PI report to the raw data to verify that the report correctly reflected the data. The documents reviewed are listed in the Attachment.
Cornerstone: Initiating Events (2 samples)
- Unit 1 Unplanned Power Changes per 7000 Critical Hours; and
- Unit 2 Unplanned Power Changes per 7000 Critical Hours.
Cornerstone: Mitigating Systems (2 samples)
- Unit 1 Mitigating Systems Performance Index, High Pressure Injection; and
- Unit 2 Mitigating Systems Performance Index, High Pressure Injection.
b. Findings
No findings of significance were identified.
4OA2 Identification and Resolution of Problems
Review of Items Entered into the CAP As required by Inspection Procedure 71152, Identification and Resolution of Problems, and in order to help identify repetitive equipment failures or specific human performance issues for follow-up, the inspectors screened all items entered into Limericks corrective action program. The inspectors accomplished this by reviewing each new condition report, attending management review committee meetings, and accessing Exelons computerized database.
4OA3 Event Follow-Up
.1 Plant Event Review
a. Inspection Scope
For the three plant events listed below, the inspectors reviewed and/or observed plant parameters, reviewed personnel performance, and evaluated performance of mitigating systems. The inspectors communicated the plant events to appropriate regional personnel and compared the event details with criteria contained in IMC 0309, Reactive Inspection Decision Basis for Reactors, for consideration of additional reactive inspection activities. The inspectors reviewed Exelons follow-up actions related to the events to assure that appropriate corrective actions were implemented commensurate with their safety significance.
- Unit 2 automatic reactor scram due to main turbine trip caused by a main generator fault on February 1, 2008 (2F40);
- Refueling floor elevated radiation levels during 1R12 due to air entrainment in the alternate decay heat removal system on March 9, 2008; and
- Unit 1 automatic reactor scram due to main turbine trip caused by invalid power/load unbalance signal on March 22, 2008 (1F43).
b. Findings
No findings of significance were identified.
.2 (Closed) Licensee Event Report (LER) 050000353/2008-002-0, Automatic Actuation of
the Reactor Protection System at Power On February 1, 2008, with the unit at 100 percent power, Unit 2 automatically scrammed due to main turbine trip following a generator lockout. The cause of the generator lockout was a fault on the A phase of the unit main transformer. The details of this event are discussed in section 1R12 of this report and resulted in a Green finding. The inspectors did not identify any new findings in review of this LER. This LER is closed.
4OA6 Meetings, Including Exit
Exit Meeting Summary
On April 10, 2008, the resident inspectors presented the inspection results to Mr. C. Mudrick and other members of his staff. The inspectors confirmed that proprietary information was not included in the inspection report.
ATTACHMENT:
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Exelon Generation Company
- C. Mudrick, Site Vice President
- E. Callan, Plant Manager
- D. DiCello, Radiation Protection Manager
- R. Dickinson, Director Engineering
- R. Kreider, Manager, Regulatory Assurance
- S. Bobyock, Manager, Plant Engineering
- S. Breeding, Manager, Operations Support
- M. Crim, Manager, Operations Services
- P. Gardner, Director Operations
- M. Gift, System Manager, Radiation Monitoring Systems
- R. Gosby, Radiation Protection Technician, Instrumentation
- C. Gray, Radiological Engineering Manager
- R. Harding, Engineer, Regulatory Assurance
- M. Jesse, Nuclear Oversight Manager
- M. Karasek, Structural Engineering
- D. Malinowski, Simulator Instructor
- J. Sprucinski, Senior Radiation Protection Technician
- P. Weyhmuller, Manager, Plant Engineering
LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED
Opened
None
Closed
- 050000353/2008-002-2 LER Automatic Actuation of the Reactor Protection System (Section 4OA3.2)
Opened and Closed
- 05000353/2008002-01 FIN Inadequate Maintenance Procedure for the 2A Main Transformer (1R12)
- 05000352/2008002-02 FIN Failure to Correct Main Turbine Bypass Valve Adverse Condition (Section 1R15)
- 05000352/2008002-03 NCV Failure to Promptly Implement Actions for a Low SST Level (Section 1R20.3)
Discussed
None