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{{Adams|number = ML073180045}}
{{Adams
| number = ML073180045
| issue date = 11/13/2007
| title = IR 05000352-07-004, 05000353-07-004; on 07/01/07-09/30/07; Limerick Generating Station, Units 1 and 2; Routine Integrated Report
| author name = Krohn P
| author affiliation = NRC/RGN-I/DRP/PB4
| addressee name = Pardee C
| addressee affiliation = Exelon Generation Co, LLC, Exelon Nuclear
| docket = 05000352, 05000353
| license number = NPF-039, NPF-085
| contact person = KROHN, PG
| document report number = IR-07-004
| document type = Inspection Report, Letter
| page count = 25
}}


{{IR-Nav| site = 05000352 | year = 2007 | report number = 004 }}
{{IR-Nav| site = 05000352 | year = 2007 | report number = 004 }}


=Text=
=Text=
{{#Wiki_filter:
{{#Wiki_filter:November 13, 2007
[[Issue date::November 13, 2007]]


Mr. Charles G. PardeePresident and CNO Exelon Nuclear Exelon Generation Company, LLC 200 Exelon Way Kennett Square, PA 19348
==SUBJECT:==
 
LIMERICK GENERATING STATION - NRC INTEGRATED INSPECTION REPORT 05000352/2007004 AND 05000353/2007004
SUBJECT: LIMERICK GENERATING STATION - NRC INTEGRATED INSPECTIONREPORT 05000352/2007004 AND 05000353/2007004


==Dear Mr. Pardee:==
==Dear Mr. Pardee:==
On September 30, 2007, the U. S. Nuclear Regulatory Commission (NRC) completed aninspection at your Limerick Generating Station Units 1 and 2. The enclosed integrated inspection report documents the inspection results which were discussed on October 15, 2007, with Mr. E. Callan and other members of your staff.The inspection examined activities conducted under your license as they relate to safety andcompliance with the Commission's rules and regulations and with the conditions of your license.
On September 30, 2007, 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 October 15, 2007, with Mr. E. Callan and other members of your staff.


The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel.Based on the results of this inspection, no findings of significance were identified.
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.


In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, itsenclosure, and your response (if any) will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of the NRC's document system (ADAMS). ADAMS is accessible from the NRC Website at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel.


Sincerely,/RA/Paul G. Krohn, ChiefProjects Branch 4 Division of Reactor ProjectsDocket Nos: 50-352, 50-353License Nos: NPF-39, NPF-85
Based on the results of this inspection, no findings of significance were identified.


===Enclosure:===
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 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).
Inspection Report 05000352/2007004 and 05000353/2007004


===w/Attachment:===
Sincerely,
Supplemental Information
/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 05000352/2007004 and 05000353/2007004 w/Attachment: Supplemental Information


=SUMMARY OF FINDINGS=
=SUMMARY OF FINDINGS=
......................................................iii
IR 05000352/2007-004, 05000353/2007-004; 07/01/2007 - 09/30/2007; Limerick Generating
 
Station, Units 1 and 2; Routine Integrated Report.
 
The report covered a three-month period of inspection by resident inspectors and announced inspections by reactor inspectors. 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===
 
No findings of significance were identified.
 
===Licensee-Identified Violations===
 
None.
 
iii


=REPORT DETAILS=
=REPORT DETAILS=
............................................................1
 
===Summary of Plant Status===
 
Unit 1 began this inspection period operating at full rated thermal power. On August 16, 2007, reactor power was reduced to 20 percent and the main generator was removed from service to repair the generator output number 11 disconnect switch. On August 17, 2007, the disconnect switch repairs were completed and the main generator was returned to service. Unit 1 returned to 100 percent power on August 18, 2007. With the exception of a planned end of summer load drop to 85 percent power on September 8, 2007, Unit 1 remained at full power for the remainder of the period.
 
Unit 2 began this inspection period operating at full rated thermal power. On August 6, 2007, reactor power decreased to 75 percent due to an unplanned speed reduction on the 2B reactor recirculation pump. The pump speed change was due to a recirculation motor generator electronic card failure. The card was replaced and Unit 2 was returned to 100 percent power later in the day. With the exception of a planned end of summer load drop to 60 percent power on September 15, 2007, Unit 2 remained at full power for the remainder of the period.


==REACTOR SAFETY==
==REACTOR SAFETY==
...........................................................11R01Adverse Weather Protection .........................................1
Cornerstones: Initiating Events, Mitigating Systems, and Barrier Integrity
{{a|1R01}}
==1R01 Adverse Weather Protection (71111.01 - 1 system sample)==
 
====a. Inspection Scope====
The inspectors evaluated Exelons preparations and protection for summer weather. On July 10, 2007, the inspectors walked down Unit 1 and Unit 2 main generators and main transformers during hot weather and a grid heavy load voltage condition. The documents reviewed are listed in the Attachment.
 
====b. Findings====
No findings of significance were identified. {{a|1R04}}
==1R04 Equipment Alignment==
{{IP sample|IP=IP 71111.04}}
===.1 Partial Walkdown===
{{IP sample|IP=IP 71111.04Q|count=4}}
 
====a. Inspection Scope====
The inspectors performed four partial walkdowns of plant systems to verify the operability of redundant or diverse trains and components when safety 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 systems:
* Unit 1 High Pressure Coolant Injection (HPCI) system;
* Unit 1 D-13 Emergency Diesel Generator (EDG);
* Unit 1 Standby Liquid Control System; and
* Unit 1 Reactor Core Isolation Cooling (RCIC).
 
===.2 Complete System Walkdown===
{{IP sample|IP=IP 71111.04S|count=1}}
The inspectors conducted one complete walkdown of the Unit 1 and Unit 2 Control Rod Drive (CRD) systems to verify functional capability of the system. The inspectors used plant TS, Exelon operating procedures, P&IDs, the UFSAR, and past surveillance tests as guidance for conducting the complete system walkdown. The inspectors reviewed the alignment of system valves, position of electrical breakers and settings of the system flow controller to ensure proper system configuration as described in plant procedures and drawings. During the walkdown, the inspectors evaluated the material condition and general housekeeping of the system and open issue reports associated with the system.
 
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
.
 
====b. Findings====
No findings of significance were identified. {{a|1R05}}
==1R05 Fire Protection==
 
===.1 Fire Protection - Tours===
{{IP sample|IP=IP 71111.05Q|count=8}}
 
====a. Inspection Scope====
The inspectors conducted a tour of the eight 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 Exelons fire plan. The documents reviewed are listed in the Attachment. The inspectors performed the following samples:
* Main Control Room and peripheral rooms;
* Unit 1 Refuel Floor;
* Unit 2 Refuel Floor;
* Unit 1 220 KV Switchyard;
* Unit 1 and Unit 2 Static Inverter compartments;
* Unit 1 and Unit 2 Standby Gas Treatment system filter compartments and access area;
* Control Room Structure fan room, Elevation 304; and
* Unit 1 D14 Diesel Generator Room.
 
===.2 Fire Protection - Drill Observation===
{{IP sample|IP=IP 71111.05A|count=1}}
 
====a. Inspection Scope====
The inspectors observed one unannounced fire drill conducted in the Unit 1 air compressor, electro-hydraulic control (EHC) power unit, and turbine lubricating oil storage tank area on September 26, 2007. The inspectors observed the drill to evaluate the readiness of the plant fire brigade to fight fires. The documents reviewed are listed in the Attachment. Specific attributes evaluated were:
* Proper donning of fire fighting turnout gear and self-contained breathing apparatus (SCBA);
* Proper use and layout of fire hoses;
* Employment of appropriate fire fighting techniques;
* Sufficient fire fighting equipment brought to the scene;
* Effectiveness of fire brigade leader communications, command, and control;
* Search for victims and propagation of fire into other plant areas;
* Smoke removal operations;
* Utilization of pre-planned strategies;
* Adherence to the pre-planned drill scenario; and
* Drill objectives.
 
====b. Findings====
No findings of significance were identified.
 
{{a|1R06}}
==1R06 Flood Protection Measures==
{{IP sample|IP=IP 71111.06|count=1}}
Internal Flooding
 
====a. Inspection Scope====
The inspectors reviewed documents and inspected structures, systems, and components (SSCs) relative to the adequacy of internal flood protection measures for the Unit 1 HPCI room. The inspectors performed walkdowns of the relevant areas to verify the adequacy of flood mitigation doors and barriers, drainage systems, and other flood protection features. The documents reviewed are listed in the Attachment.
 
====b. Findings====
No findings of significance were identified.
 
{{a|1R11}}
==1R11 Licensed Operator Requalification Program==
{{IP sample|IP=IP 71111.11Q|count=1}}
 
===Resident Inspector Quarterly Review (1 sample)===
 
====a. Inspection Scope====
On August 28, 2007, the inspectors observed a licensed operator requalification simulator scenario. The scenario included a simulated spurious Division 1 Loss of Coolant Accident (LOCA) signal with failure of the D11 EDG to start and an unisolable reactor water cleanup leak, which resulted in a manual scram and emergency blowdown.
 
The inspectors observed the performance of two operating crews responding to the same scenario. The inspectors assessed licensed operator performance, including operator 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 simulation. The documents reviewed are listed in the Attachment.
 
====b. Findings====
No findings of significance were identified.
 
{{a|1R12}}
==1R12 Maintenance Effectiveness==
{{IP sample|IP=IP 71111.12|count=3}}
 
====a. Inspection Scope====
The inspectors evaluated Exelons work practices and follow-up corrective actions for 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 Attachment. The inspectors performed the following samples:
* 1A post LOCA recombiner maintenance rule (a)(1) determination;
* 2B Turbine Enclosure Cooling Water heat exchanger system outage window; and
* Unit 2 High Pressure Coolant Injection maintenance rule (a)(1) determination.
 
{{a|1R13}}
==1R13 Maintenance Risk Assessments and Emergent Work Control==
{{IP sample|IP=IP 71111.13|count=8}}
 
====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 risk assessments for the following issues:
* Incorrect interpretation of ASME Code Case N-435-1;
* Unit 1 HPCI room temperature high;
* Unit 2 Reactor Recirculation Motor Generator runback to minimum speed;
* Unit 1 Main Generator Disconnect high temperatures;
* Unit 1 Main Generator Disconnect phases A and C jumper installation;
* Large VAR (Volt-Ampere Reactive) swings during EDG run;
* Unit 2 placing alternate steam jet air ejector in service; and
* Unit 1 D Safety Relief Valve position indicator converter module replacement.
 
====b. Findings====
No findings of significance were identified.
 
{{a|1R15}}
==1R15 Operability Evaluations==
{{IP sample|IP=IP 71111.15|count=5}}
 
====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 (IRs) to verify that Exelon identified and corrected deficiencies associated with operability evaluations. The documents reviewed are listed in the Attachment. The inspectors reviewed operability evaluations for the following components:
* Unit 2 HPCI HV-055-2F006;
* Unit 1 HPCI Room Cooler;
* Unit 2 Reactor Core Isolation Cooling Pump Suction High Pressure Alarm;
* Unit 2 HPCI Oil Pressure; and
* Unit 2B Reactor Circulation Pump mechanical seal.
 
====b. Findings====
No findings of significance were identified.
 
{{a|1R19}}
==1R19 Post-Maintenance Testing==
{{IP sample|IP=IP 71111.19|count=8}}
 
====a. Inspection Scope====
The inspectors reviewed the eight 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 applicable 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 Attachment. The inspectors reviewed post-maintenance tests for the following systems and components:
* C Residual Heat Removal Service Water pump;
* 2A RHR Suppression Pool Cooling Valve;
* D Emergency Diesel Generator;
* D21 Diesel Generator;
* Unit 1 A Standby Liquid Control Squib Valve;
* Unit 1 Reactor Core Isolation Cooling Flow Controller;
* Unit 2 Reactor Core Isolation Cooling Outboard Steam Isolation Valve; and
* Unit 2 Redundant Reactivity Control System (RRCS).
 
====b. Findings====
No findings of significance were identified.
 
{{a|1R22}}
==1R22 Surveillance Testing==
{{IP sample|IP=IP 71111.22|count=5}}
 
====a. Inspection Scope====
The inspectors witnessed the performance and reviewed test data for five surveillance tests that are associated with selected 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 the surveillance tests for the following systems and components:
* Unit 2 D24 EDG;
* Unit 2 Division 2 Lower Pressure Coolant Injection;
* Unit 2 Control Rods;
* Unit 1 High Pressure Coolant Injection Pump; and
* Unit 1 High Pressure Coolant Injection.
 
====b. Findings====
No findings of significance were identified.
 
{{a|1R23}}
==1R23 Temporary Plant Modifications==
{{IP sample|IP=IP 71111.23|count=1}}
 
====a. Inspection Scope====
The inspectors reviewed and compared the temporary modification listed below with the UFSAR and TS to verify that the modification did not affect operability or availability of the Unit 1 reactor recirculation motor generator. 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 appropriate revisions were made to reflect the temporary configuration change. Additionally, the inspectors evaluated the adequacy of proposed testing upon removal of the change. The documents reviewed are listed in the
. The inspectors performed the following sample:
* TRT-D7-164, Install 1B Reactor Recirculation Pump Motor Generator Temporary Mechanical Stop.
 
====b. Findings====
No findings of significance were identified.
 
===Cornerstone: Emergency Preparedness (EP)===
 
{{a|1EP6}}
==1EP6 Drill Evaluation==
{{IP sample|IP=IP 71114.06|count=2}}
 
===.1 General Emergency Classification due to Simulated Fuel Failure Coincident with Failed===


{{a|1R04}}
Open Main Steam Line Isolation Valves
==1R04 Equipment Alignment ..............................................1==


{{a|1R05}}
====a. Inspection Scope====
==1R05 Fire Protection....................................................2==
On June 19, 2007, the inspectors observed an EP training drill in the control room simulator. The inspectors assessed Exelon's emergency response organization's (ERO)implementation of the Limerick emergency plan and implementing procedures, and the ERO's response to simulated degraded plant conditions to identify weaknesses and deficiencies in classification, notification, and protective action recommendation (PAR)development activities. In addition, the inspectors assessed licensed operator performance required to ensure the safe operation of the reactor and the protection of the nuclear fuel and primary containment barriers. The inspectors reviewed Exelons training evaluators' critiques and the formal critique report, dated July 31, 2007, associated with the EP drill, to evaluate Exelon's identification of weaknesses and deficiencies. The inspectors compared inspector observed weaknesses with those identified in Exelon's formal drill critique to verify whether Exelon adequately identified weaknesses and deficiencies at an appropriate threshold. The documents reviewed are listed in the Attachment.


{{a|1R06}}
====b. Findings====
==1R06 Flood Protection Measures ..........................................31R11Licensed Operator Requalification Program .............................3==
No findings of significance were identified.


{{a|1R12}}
===.2 Site Area Emergency Classification Due to a Simulated Reactor Coolant System Leak in===
==1R12 Maintenance Effectiveness ..........................................41R13Maintenance Risk Assessments and Emergent Work Control................41R15Operability Evaluations .............................................51R19Post-Maintenance Testing ..........................................51R22Surveillance Testing ...............................................6==


{{a|1R23}}
the Reactor Building
==1R23 Temporary Plant Modifications .......................................6==


1EP6Drill Evaluation
====a. Inspection Scope====
The inspectors observed a licensed operator requalification simulator exercise evaluation to identify the timing and adequacy of classification, notification, and PAR development activities. During the simulator evaluation, the inspectors reviewed checklists and forms used for classification and notification activities, and compared them to the criteria in Exelons Emergency Plan, EP-MA-114-100-F-01, State/Local Event Notification Form, and supporting procedures. The documents reviewed are listed in the Attachment.
 
====b. Findings====
No findings of significance were identified.


==OTHER ACTIVITIES==
==OTHER ACTIVITIES==
..........................................................84OA1Performance Indicator (PI) Verification .................................8 4OA3Event Followup ...................................................9 4OA6Meetings, Including Exit............................................11ATTACHMENT:
 
{{a|4OA1}}
==4OA1 Performance Indicator (PI) Verification==
{{IP sample|IP=IP 71151|count=8}}
 
Inspection Scope The inspector sampled Exelons submittal of the performance indicators listed below to verify the accuracy of the data recorded from the third quarter of 2006 through the third quarter of 2007. 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 main control room logs, issue reports, power history curves, work orders, and system derivation 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 (6 samples)===
* Unit 1 High Pressure Coolant Injection system;
* Unit 2 High Pressure Coolant Injection system;
* Unit 1 Reactor Core Isolation Cooling system;
* Unit 2 Reactor Core Isolation Cooling system;
* Unit 1 Emergency Diesel Generators; and
* Unit 2 Emergency Diesel Generators.
 
====b. Findings====
No findings of significance were identified. {{a|4OA2}}
==4OA2 Identification and Resolution of Problems==
{{IP sample|IP=IP 71152}}
Review of Items Entered into the Corrective Action Program (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 performed a screening of all items entered into Limericks CAP. The inspectors accomplished this by reviewing the description of each new issue report and accessing Exelons computerized database. The documents reviewed are listed in the Attachment.
 
====b. Findings====
No findings of significance were identified. The inspectors observed that issues selected for review were appropriately categorized and prioritized in accordance with Exelons corrective action process.
{{a|4OA3}}
==4OA3 Event Followup==
{{IP sample|IP=IP 71153}}
===.1 Unit 1 Main Generator Output Switchyard Disconnect Removal from Service due to High===
 
Temperature
 
====a. Inspection Scope====
On August 16, 2007, the inspectors responded to the plant due to a high temperature on the Unit 1 main generator output disconnect. The inspectors discussed the switchyard disconnect problem with operations personnel, engineering personnel, and Exelon management to gain an understanding of Exelons response and follow-up actions. The inspectors reviewed troubleshooting activities, the disconnect temperature surveillance monitoring, and the planned actions to repair and correct the disconnect high temperature condition.
 
The number 11 disconnect is located on the output of the Unit 1 main transformers and is physically located in the Unit 1 220 kilovolt (kV) switchyard. The disconnect is comprised of three individual disconnects and associated bus bars. The disconnect B phase temperature reached a maximum value of 375 degrees Celsius and resulted in reactor power reductions to lower the temperature. The location of the elevated temperature was at the movable hinged section of the disconnect. The "A" and "C" phase temperatures were 95 to 100 degrees Celsius. The B phase high temperature was discovered during ongoing monthly temperature monitoring.
 
In response to the high temperature, operators reduced reactor power from 100 percent down to 25 percent to reduce the disconnect temperature and support removal of the main generator and disconnect from service to perform repairs. The inspectors observed just-in-time training in the simulator that was given to the operators prior to removing the main generator and disconnect from service. The inspectors also observed the operators removal of the main generator and disconnect from service to support repairs.
 
After removal from service, the B phase disconnect was rebuilt and tested satisfactorily prior to being returned to service. The main generator was placed back in service and the plant was returned to 100 percent power. The documents reviewed are listed in the
.
 
====b. Findings====
No findings of significance were identified.
 
===.2 (Closed) LER 05000353/02007-001, Scram Discharge Volume Vent and Drain Valves===
 
Failed Open Due to Clearance Tagging Error On March 10, 2007, Limerick Unit 2 was in hot shutdown and depressurized to approximately 25 psig for the 2R09 refueling outage. A full scram signal was present and the scram discharge volume (SDV) was isolated, as designed. Operators were in the process of applying a clearance in preparation for planned maintenance on the Reactor Protection System and the scram air header. As part of this clearance, operators removed the Reactor Protection System backup scram fuses which ultimately resulted in the SDV vent and drain valves opening unexpectedly. Water from the SDV began to vent through these open valves into the plant drain system. Station personnel discovered the condition and closed the SDV vent and drain valves, stopping the source of the water. Further investigation by the station determined that the inadvertent opening of the SDV vent and drain valves was due to an improperly written clearance.
 
A non-cited violation (NCV) associated with this issue was documented in Section 1R20 of NRC integrated inspection report 05000352/2007002 and 05000353/2007002. The inspectors reviewed this LER and did not identify any additional findings of significance.
 
Exelon documented this event and associated corrective actions in IR 602042. The documents reviewed are listed in the Attachment. This LER is closed.
 
===.3 (Closed) LER 05000353/02007-002, Valid Actuation of Main Condenser Low Vacuum===
 
Isolation Logic During Outage On March 12, 2007, operators were in the process of lowering vacuum on Limerick Unit 2 as part of refueling outage activities in accordance with procedure S07.2.A, Shutdown of the Steam Jet Air Ejector and Breaking Main Condenser Vacuum. During this evolution, the main condenser low vacuum main steam isolation valve (MSIV) isolation logic actuated unexpectedly. Further investigation revealed that due to a procedural execution error, station personnel had only bypassed two of the required four channels of the isolation logic. Even though this resulted in actuation of two channels of logic when vacuum was lowered, no valves actually repositioned since the MSIVs and other affected valves were closed earlier as required by procedure. This failure to comply with procedure S07.2.A constitutes a violation of minor significance that is not subject to enforcement action in accordance with Section IV of the NRCs enforcement policy. The inspectors reviewed this LER and did not identify any additional findings of significance.
 
Exelon documented this event and associated corrective actions in IR 602921. This LER is closed.
 
===.4 (Closed) LER 05000353/02007-003, Automatic Actuation of the Reactor Protection===
 
System at Power On April 24, 2007, the Unit 2 Reactor Protection System automatically actuated when reactor water level decreased from +35 inches to +12.5 inches. All control rods fully inserted. When reactor level decreased to the low-low level setpoint of -38 inches, both HPCI and RCIC systems initiated and injected into the vessel. HPCI and RCIC were placed in manual mode when flow oscillations were observed on both systems. Both systems were automatically secured when reactor level increased to +54 inches.
 
Exelons investigation determined that a circuit card in Redundant Reactivity Control System (RRCS) Division 1, channel B spuriously actuated while channel A was in a tripped condition due to planned surveillance testing. This resulted in a feedwater runback. The feedwater runback reduced reactor level as expected.
 
Exelons investigation determined that HPCI and RCIC flow oscillations were due to flow control loop tuning settings that did not properly account for differences in flow path testing conditions and vessel injection flow conditions. Station personnel replaced and successfully tested the affected RRCS circuit card. In addition the HPCI and RCIC flow controller gain and reset settings were adjusted to be consistent with Unit 1 settings, which are consistent with industry values and similar to previous Unit 2 settings when stable flow was demonstrated during Unit 2 initial startup testing. The procedure for tuning of HPCI and RCIC flow controls was revised to specify the required gain and reset settings.
 
The inspectors reviewed Exelons apparent cause investigation, Unit 2 TS, and notification requirements. The apparent cause investigation determined that the HPCI and RCIC gain and reset settings were changed during system tuning in May 1999; therefore, this condition existed for approximately 8 years. This resulted in a condition that could have prevented the safety function of Unit 2 HPCI. A non-cited violation (NCV)associated with this issue was documented in Section IR19 of NRC integrated inspection report 05000352/2007003 and 05000353/2007003. Exelon documented this issue and its corrective actions in IR 620861. The review determined that Unit 1 was not affected.
 
The inspectors reviewed the corrective actions, including revised procedures, and found no additional findings or unresolved issues. The documents reviewed are listed in the
. This LER is closed.
 
{{a|4OA6}}
==4OA6 Meetings, Including Exit==
 
===Exit Meeting Summary===
 
On October 15, 2007, the resident inspectors presented the inspection results to Mr. E. Callan and other members of his staff. The inspectors confirmed that proprietary information was not included in the inspection report.
 
ATTACHMENT:  


=SUPPLEMENTAL INFORMATION=
=SUPPLEMENTAL INFORMATION=


==KEY POINTS OF CONTACT==
==KEY POINTS OF CONTACT==
..................................................A-1
 
Exelon Generation Company
: [[contact::C. Mudrick]], Site Vice President
: [[contact::E. Callan]], Plant Manager
: [[contact::D. DiCello]], Radiation Protection Manager
: [[contact::R. Dickinson]], Director Engineering
: [[contact::J. Berg]], System Manager, HPCI and RCIC
: [[contact::J. George]], System Manager, Remote Shutdown Panel
: [[contact::M. Gift]], System Manager, Radiation Monitoring Systems
: [[contact::R. Gosby]], Radiation Protection Technician, Instrumentation
: [[contact::R. Harding]], Engineer, Regulatory Assurance
: [[contact::R. Kreider]], Manager, Regulatory Assurance
: [[contact::D. Malinowski]], Simulator Instructor
: [[contact::B. Tracy]], System Manager
: [[contact::P. Tarpinian]], PRA Engineer
: [[contact::D. Boylan]], Summer Readiness Coordinator
: [[contact::R. Newmaster]], Manager - Emergency Preparedness, Limerick
: [[contact::J. Broillet]], Operations Shift Manager
 
==LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED==
==LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED==
.............................A-1
 
===Closed===
: 05000353/2007-001-0                  LER        Scram Discharge Volume Vent and Drain Valves Failed Open due to Clearance Tagging Error (Section 40A3.2)
: 05000353/2007-002-0                  LER        Valid Actuation of Main Condenser Low Vacuum Isolation Logic During Outage (Section 40A3.3)
: 05000353/2007-003                    LER        Automatic Actuation of the Reactor Protection System at Power (Section 40A3.4)
 
===Discussed===
 
None
 
==LIST OF DOCUMENTS REVIEWED==
==LIST OF DOCUMENTS REVIEWED==
.......................................................................................... A-2
==LIST OF ACRONYMS==
........................................................A-8
iiiSUMMARY
: [[OF]] [[]]
FINDINGSIR 05000352/2007-004, 05000353/2007-004; 07/01/2007 - 09/30/2007; Limerick GeneratingStation, Units 1 and 2; Routine Integrated Report.The report covered a three-month period of inspection by resident inspectors and announcedinspections by reactor inspectors. The NRC's program for overseeing the safe operation of
commercial nuclear power reactors is described in
: [[NUR]] [[]]
EG-1649, "Reactor Oversight," Revision
4, dated December
: [[2006.A.N]] [[]]
: [[RC]] [[-Identified and Self-Revealing FindingsNo findings of significance were identified.B. Licensee-Identified ViolationsNone.]]
: [[REPORT]] [[]]
DETAILSSummary of Plant StatusUnit 1 began this inspection period operating at full rated thermal power. On August 16, 2007,reactor power was reduced to 20 percent and the main generator was removed from service to
repair the generator output number 11 disconnect switch. On August 17, 2007, the disconnect
switch repairs were completed and the main generator was returned to service. Unit 1 returned
to 100 percent power on August 18, 2007. With the exception of a planned end of summer load
drop to 85 percent power on September 8, 2007, Unit 1 remained at full power for the remainder
of the period.


Unit 2 began this inspection period operating at full rated thermal power. On August 6, 2007,
reactor power decreased to 75 percent due to an unplanned speed reduction on the 2B reactor
recirculation pump. The pump speed change was due to a recirculation motor generator
electronic card failure. The card was replaced and Unit 2 was returned to 100 percent power
later in the day. With the exception of a planned end of summer load drop to 60 percent power
on September 15, 2007, Unit 2 remained at full power for the remainder of the period. 1.
: [[REACTO]] [[R]]
SAFETYCornerstones: Initiating Events, Mitigating Systems, and Barrier Integrity1R01Adverse Weather Protection (71111.01 - 1 system sample)      a.Inspection ScopeThe inspectors evaluated Exelon's preparations and protection for summer weather. OnJuly 10, 2007, the inspectors walked down Unit 1 and Unit 2 main generators and main
transformers during hot weather and a grid heavy load voltage condition. The
documents reviewed are listed in the Attachment.      b.FindingsNo findings of significance were identified.1R04Equipment Alignment (71111.04) .1    Partial Walkdown (71111.04Q - 4 samples)      a.Inspection ScopeThe inspectors performed four partial walkdowns of plant systems to verify the operabilityof redundant or diverse trains and components when safety equipment in the opposite
train was either inoperable, undergoing surveillance testing, or potentially degraded. The
inspectors used plant Technical Specifications (TS), Exelon operating procedures, plantpiping 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.
2Enclosure During the walkdown, the inspectors evaluated material condition and generalhousekeeping of the system and adjacent spaces. The documents reviewed are listed in
the Attachment. The inspectors performed walkdowns of the following systems:*Unit 1 High Pressure Coolant Injection (HPCI) system;*Unit 1 D-13 Emergency Diesel Generator (EDG);
*Unit 1 Standby Liquid Control System; and
*Unit 1 Reactor Core Isolation Cooling (RCIC)..2Complete System Walkdown  (71111.04S - 1 sample)The inspectors conducted one complete walkdown of the Unit 1 and Unit 2 Control RodDrive (CRD) systems to verify functional capability of the system. The inspectors used
plant
: [[TS]] [[, Exelon operating procedures, P&]]
: [[ID]] [[s, the]]
: [[UFS]] [[]]
AR, and past surveillance tests
as guidance for conducting the complete system walkdown. The inspectors reviewed the
alignment of system valves, position of electrical breakers and settings of the system flow
controller to ensure proper system configuration as described in plant procedures and
drawings. During the walkdown, the inspectors evaluated the material condition and
general housekeeping of the system and open issue reports associated with the system.
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.FindingsNo findings of significance were identified.1R05Fire Protection.1Fire Protection - Tours  (71111.05Q - 8 samples)      a.Inspection Scope The inspectors conducted a tour of the eight areas listed below to assess the materialcondition and operational status of fire protection features. The inspectors verified that
combustibles and ignition sources were controlled in accordance with Exelon's
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
Exelon's fire plan. The documents reviewed are listed in the Attachment. The inspectors
performed the following samples:*Main Control Room and peripheral rooms;*Unit 1 Refuel Floor;
*Unit 2 Refuel Floor;
*Unit 1 220 KV Switchyard;
*Unit 1 and Unit 2 Static Inverter compartments;
*Unit 1 and Unit 2 Standby Gas Treatment system filter compartments and accessarea;
3Enclosure *Control Room Structure fan room, Elevation 304; and*Unit 1 D14 Diesel Generator Room..2Fire Protection - Drill Observation (71111.05A - 1 sample)    a.Inspection ScopeThe inspectors observed one unannounced fire drill conducted in the Unit 1 aircompressor, electro-hydraulic control (EHC) power unit, and turbine lubricating oil
storage tank area on September 26, 2007. The inspectors observed the drill to evaluate
the readiness of the plant fire brigade to fight fires. The documents reviewed are listed in
the Attachment. Specific attributes evaluated were:*Proper donning of fire fighting turnout gear and self-contained breathingapparatus (SCBA); *Proper use and layout of fire hoses;
*Employment of appropriate fire fighting techniques;
*Sufficient fire fighting equipment brought to the scene;
*Effectiveness of fire brigade leader communications, command, and control;
*Search for victims and propagation of fire into other plant areas;
*Smoke removal operations;
*Utilization of pre-planned strategies;
*Adherence to the pre-planned drill scenario; and
*Drill objectives.      b.FindingsNo findings of significance were identified.1R06Flood Protection Measures  (71111.06 - 1 sample)Internal Flooding      a.Inspection Scope The inspectors reviewed documents and inspected structures, systems, and components(SSCs) relative to the adequacy of internal flood protection measures for the Unit
: [[1 HP]] [[]]
CI
room. The inspectors performed walkdowns of the relevant areas to verify the adequacy
of flood mitigation doors and barriers, drainage systems, and other flood protection
features. The documents reviewed are listed in the Attachment.      b.Findings No findings of significance were identified.1R11Licensed Operator Requalification Program (71111.11Q - 1 sample)Resident Inspector Quarterly Review (1 sample)      a.Inspection Scope
4Enclosure On August 28, 2007, the inspectors observed a licensed operator requalificationsimulator scenario. The scenario included a simulated spurious Division 1 Loss of
Coolant Accident (LOCA) signal with failure of the D11 EDG to start and an unisolablereactor water cleanup leak, which resulted in a manual scram and emergency blowdown.
The inspectors observed the performance of two operating crews responding to the
same scenario. The inspectors assessed licensed operator performance, including
operator 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 simulation. The documents reviewed are listed in the Attachment.      b.FindingsNo findings of significance were identified.1R12Maintenance Effectiveness  (71111.12 - 3 samples)    a.Inspection Scope The inspectors evaluated Exelon's work practices and follow-up corrective actions forSSCs and identified issues to assess the effectiveness of Exelon's maintenance
activities. The inspectors reviewed the performance history of risk significant SSCs and
assessed Exelon's extent-of-condition determinations for those issues with potential
common cause or generic implications to evaluate the adequacy of the station's
corrective actions. The inspectors assessed Exelon's 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 Exelon's corrective actions that were
taken or planned, to evaluate whether the actions were reasonable and appropriate. The
documents reviewed are listed in the Attachment. The inspectors performed the
following samples:*1A post
: [[LO]] [[]]
CA recombiner maintenance rule (a)(1) determination;*2B Turbine Enclosure Cooling Water heat exchanger system outage window; and
*Unit 2 High Pressure Coolant Injection maintenance rule (a)(1) determination.1R13Maintenance Risk Assessments and Emergent Work Control (71111.13 - 8 samples)      a.Inspection Scope The inspectors evaluated the effectiveness of Exelon's maintenance risk assessmentsrequired by 10 CFR 50.65 (a)(4). This inspection included discussion with control room
operators and risk analysis personnel regarding the use of Exelon's 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 Exelon's risk management actions, for both planned and emergent work, were
5Enclosure consistent with those described in Exelon procedure,
: [[ER]] [[-]]
AA-600-1042, "On-Line RiskManagement."  The documents reviewed are listed in the Attachment. Inspectors
reviewed risk assessments for the following issues:*Incorrect interpretation of
: [[ASME]] [[Code Case N-435-1;*Unit 1]]
HPCI room temperature high;
*Unit 2 Reactor Recirculation Motor Generator runback to minimum speed;
*Unit 1 Main Generator Disconnect high temperatures;
*Unit 1 Main Generator Disconnect phases A and C jumper installation;
*Large
: [[VAR]] [[(Volt-Ampere Reactive) swings during]]
EDG run;
*Unit 2 placing alternate steam jet air ejector in service; and
*Unit 1 "D" Safety Relief Valve position indicator converter module replacement.      b.FindingsNo findings of significance were identified.1R15Operability Evaluations  (71111.15 - 5 samples)      a.Inspection ScopeFor the five operability evaluations described below, the inspectors assessed thetechnical 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
: [[UFS]] [[]]
AR 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 (IRs) to verify that Exelon identified and corrected
deficiencies associated with operability evaluations. The documents reviewed are listed
in the Attachment. The inspectors reviewed operability evaluations for the following
components:*Unit
: [[2 HPCI]] [[]]
: [[HV]] [[-055-2F006;*Unit]]
: [[1 HP]] [[]]
CI Room Cooler;
*Unit 2 Reactor Core Isolation Cooling Pump Suction High Pressure Alarm;
*Unit
: [[2 HP]] [[]]
CI Oil Pressure; and
*Unit 2B Reactor Circulation Pump mechanical seal.      b.FindingsNo findings of significance were identified.1R19Post-Maintenance Testing (71111.19 - 8 samples)      a. Inspection ScopeThe inspectors reviewed the eight post-maintenance tests (PMTs) listed below to verifythat procedures and test activities ensured system operability and functional capability.
The inspectors reviewed Exelon's test procedures to verify that the procedures
6Enclosure adequately tested the safety functions that may have been affected by the maintenanceactivity, and that the applicable 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 Attachment. The
inspectors reviewed post-maintenance tests for the following systems and components:*"C" Residual Heat Removal Service Water pump;*"2A" RHR Suppression Pool Cooling Valve;
*"D" Emergency Diesel Generator;
*D21 Diesel Generator;
*Unit 1 "A" Standby Liquid Control Squib Valve;
*Unit 1 Reactor Core Isolation Cooling Flow Controller;
*Unit 2 Reactor Core Isolation Cooling Outboard Steam Isolation Valve; and
*Unit 2 Redundant Reactivity Control System (RRCS).      b.FindingsNo findings of significance were identified.1R22Surveillance Testing (71111.22 - 5 samples)      a.Inspection ScopeThe inspectors witnessed the performance and reviewed test data for five surveillancetests that are associated with selected 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 the surveillance tests for the following
systems and components:*Unit 2 D24 EDG;*Unit 2 Division 2 Lower Pressure Coolant Injection;
*Unit 2 Control Rods;
*Unit 1 High Pressure Coolant Injection Pump; and
*Unit 1 High Pressure Coolant Injection. b. FindingsNo findings of significance were identified.1R23Temporary Plant Modifications  (71111.23 - 1 sample)      a.Inspection ScopeThe inspectors reviewed and compared the temporary modification listed below with theUFSAR and TS to verify that the modification did not affect operability or availability of
the Unit 1 reactor recirculation motor generator. The inspectors ensured that station
7Enclosure personnel implemented the modification in accordance with the applicable temporaryconfiguration change process. The inspectors also reviewed the impact on existing
procedures to verify appropriate revisions were made to reflect the temporary
configuration change. Additionally, the inspectors evaluated the adequacy of proposed
testing upon removal of the change. The documents reviewed are listed in the
Attachment. The inspectors performed the following sample:*TRT-D7-164, Install 1B Reactor Recirculation Pump Motor Generator TemporaryMechanical Stop. b. FindingsNo findings of significance were identified.
Cornerstone: Emergency Preparedness (EP)1EP6Drill Evaluation (71114.06 - 2 samples).1General Emergency Classification due to Simulated Fuel Failure Coincident with FailedOpen Main Steam Line Isolation Valves      a.Inspection ScopeOn June 19, 2007, the inspectors observed an
: [[EP]] [[training drill in the control roomsimulator. The inspectors assessed Exelon's emergency response organization's (]]
ERO)
implementation of the Limerick emergency plan and implementing procedures, and the
ERO's response to simulated degraded plant conditions to identify weaknesses and
deficiencies in classification, notification, and protective action recommendation (PAR)
development activities. In addition, the inspectors assessed licensed operator
performance required to ensure the safe operation of the reactor and the protection of
the nuclear fuel and primary containment barriers. The inspectors reviewed Exelon's
training evaluators' critiques and the formal critique report, dated July 31, 2007,
associated with the EP drill, to evaluate Exelon's identification of weaknesses and
deficiencies. The inspectors compared inspector observed weaknesses with those
identified in Exelon's formal drill critique to verify whether Exelon adequately identified
weaknesses and deficiencies at an appropriate threshold. The documents reviewed are
listed in the Attachment.      b.FindingsNo findings of significance were identified..2Site Area Emergency Classification Due to a Simulated Reactor Coolant System Leak inthe Reactor Building      a.Inspection ScopeThe inspectors observed a licensed operator requalification simulator exercise evaluationto identify the timing and adequacy of classification, notification, and PAR development
activities. During the simulator evaluation, the inspectors reviewed checklists and forms
8Enclosure used for classification and notification activities, and compared them to the criteria inExelon's Emergency Plan,
: [[EP]] [[-]]
MA-114-100-F-01, "State/Local Event Notification Form,"
and supporting procedures. The documents reviewed are listed in the Attachment.      b.FindingsNo findings of significance were identified.2.OTHER
: [[ACTIVI]] [[]]
: [[TIES]] [[]]
: [[4OA]] [[1Performance Indicator (]]
PI) Verification (71151- 8 samples)    1. Inspection ScopeThe inspector sampled Exelon's submittal of the performance indicators listed below toverify the accuracy of the data recorded from the third quarter of 2006 through the third
quarter of 2007. 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 main control room
logs, issue reports, power history curves, work orders, and system derivation 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 (6 samples)*Unit 1 High Pressure Coolant Injection system;*Unit 2 High Pressure Coolant Injection system;
*Unit 1 Reactor Core Isolation Cooling system;
*Unit 2 Reactor Core Isolation Cooling system;
*Unit 1 Emergency Diesel Generators; and
*Unit 2 Emergency Diesel Generators.      b.FindingsNo findings of significance were identified.4OA2Identification and Resolution of Problems (71152)Review of Items Entered into the Corrective Action Program (CAP)
9Enclosure 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 performed a screening of all items entered into
Limerick's CAP. The inspectors accomplished this by reviewing the description of each
new issue report and accessing Exelon's computerized database. The documents
reviewed are listed in the Attachment. b. FindingsNo findings of significance were identified. The inspectors observed that issues selectedfor review were appropriately categorized and prioritized in accordance with Exelon's
corrective action process.4OA3Event Followup (71153).1Unit 1 Main Generator Output Switchyard Disconnect Removal from Service due to HighTemperature    a.Inspection ScopeOn August 16, 2007, the inspectors responded to the plant due to a high temperature onthe Unit 1 main generator output disconnect. The inspectors discussed the switchyard
disconnect problem with operations personnel, engineering personnel, and Exelon
management to gain an understanding of Exelon's response and follow-up actions. The
inspectors reviewed troubleshooting activities, the disconnect temperature surveillance
monitoring, and the planned actions to repair and correct the disconnect high
temperature condition. The number 11 disconnect is located on the output of the Unit 1 main transformers and isphysically located in the Unit 1 220 kilovolt (kV) switchyard. The disconnect is comprised
of three individual disconnects and associated bus bars. The disconnect "B" phase
temperature reached a maximum value of 375 degrees Celsius and resulted in reactor
power reductions to lower the temperature. The location of the elevated temperature
was at the movable hinged section of the disconnect. The "A" and "C" phase
temperatures were 95 to 100 degrees Celsius. The "B" phase high temperature was
discovered during ongoing monthly temperature monitoring. In response to the high temperature, operators reduced reactor power from 100 percentdown to 25 percent to reduce the disconnect temperature and support removal of the
main generator and disconnect from service to perform repairs. The inspectors observed
"just-in-time training" in the simulator that was given to the operators prior to removing
the main generator and disconnect from service. The inspectors also observed the
operators' removal of the main generator and disconnect from service to support repairs.
After removal from service, the "B" phase disconnect was rebuilt and tested satisfactorily
prior to being returned to service. The main generator was placed back in service and
the plant was returned to 100 percent power. The documents reviewed are listed in the
Attachment.      b.Findings
10Enclosure No findings of significance were identified..2(Closed) LER 05000353/02007-001, Scram Discharge Volume Vent and Drain Valves Failed Open Due to Clearance Tagging ErrorOn March 10, 2007, Limerick Unit 2 was in hot shutdown and depressurized toapproximately 25 psig for the 2R09 refueling outage. A full scram signal was present
and the scram discharge volume (SDV) was isolated, as designed. Operators were in
the process of applying a clearance in preparation for planned maintenance on the
Reactor Protection System and the scram air header. As part of this clearance,
operators removed the Reactor Protection System backup scram fuses which ultimately
resulted in the
: [[SDV]] [[vent and drain valves opening unexpectedly. Water from the]]
SDV
began to vent through these open valves into the plant drain system. Station personnel
discovered the condition and closed the SDV vent and drain valves, stopping the source
of the water. Further investigation by the station determined that the inadvertent opening
of the
: [[SDV]] [[vent and drain valves was due to an improperly written clearance. A non-cited violation (]]
NCV) associated with this issue was documented in Section 1R20of NRC integrated inspection report 05000352/2007002 and 05000353/2007002. The
inspectors reviewed this LER and did not identify any additional findings of significance.
Exelon documented this event and associated corrective actions in IR 602042. The
documents reviewed are listed in the Attachment. This
: [[LER]] [[is closed..3(Closed)]]
LER 05000353/02007-002, Valid Actuation of Main Condenser Low Vacuum Isolation Logic During OutageOn March 12, 2007, operators were in the process of lowering vacuum on Limerick Unit 2as part of refueling outage activities in accordance with procedure S07.2.A, "Shutdown of
the Steam Jet Air Ejector and Breaking Main Condenser Vacuum."  During this evolution,
the main condenser low vacuum main steam isolation valve (MSIV) isolation logic
actuated unexpectedly. Further investigation revealed that due to a procedural execution
error, station personnel had only bypassed two of the required four channels of the
isolation logic. Even though this resulted in actuation of two channels of logic when
vacuum was lowered, no valves actually repositioned since the
: [[MS]] [[]]
IVs and other affected
valves were closed earlier as required by procedure. This failure to comply with
procedure S07.2.A constitutes a violation of minor significance that is not subject to
enforcement action in accordance with Section
: [[IV]] [[of the]]
NRC's enforcement policy. The
inspectors reviewed this LER and did not identify any additional findings of significance.
Exelon documented this event and associated corrective actions in
: [[IR]] [[602921. This]]
: [[LER]] [[is closed.        .4(Closed) LER 05000353/02007-003, Automatic Actuation of the Reactor ProtectionSystem at PowerOn April 24, 2007, the Unit 2 Reactor Protection System automatically actuated whenreactor water level decreased from +35 inches to +12.5 inches. All control rods fullyinserted. When reactor level decreased to the low-low level setpoint of -38 inches, both]]
: [[HPCI]] [[and]]
: [[RCIC]] [[systems initiated and injected into the vessel.]]
: [[HPCI]] [[and]]
RCIC were
placed in manual mode when flow oscillations were observed on both systems. Both
systems were automatically secured when reactor level increased to +54 inches.
11Enclosure Exelon's investigation determined that a circuit card in Redundant Reactivity ControlSystem (RRCS) Division 1, channel "B" spuriously actuated while channel "A" was in a
tripped condition due to planned surveillance testing. This resulted in a feedwater
runback. The feedwater runback reduced reactor level as expected.Exelon's investigation determined that
: [[HPCI]] [[and]]
RCIC flow oscillations were due to flowcontrol loop tuning settings that did not properly account for differences in flow path
testing conditions and vessel injection flow conditions. Station personnel replaced and
successfully tested the affected
: [[RRCS]] [[circuit card. In addition the]]
: [[HPCI]] [[and]]
: [[RC]] [[]]
IC flow
controller gain and reset settings were adjusted to be consistent with Unit 1 settings,
which are consistent with industry values and similar to previous Unit 2 settings when
stable flow was demonstrated during Unit 2 initial startup testing. The procedure for
tuning of
: [[HPCI]] [[and]]
RCIC flow controls was revised to specify the required gain and reset
settings.The inspectors reviewed Exelon's apparent cause investigation, Unit
: [[2 TS]] [[, andnotification requirements. The apparent cause investigation determined that the]]
: [[HPCI]] [[and]]
: [[RC]] [[]]
IC gain and reset settings were changed during system tuning in May 1999;
therefore, this condition existed for approximately 8 years. This resulted in a condition
that could have prevented the safety function of Unit
: [[2 HPCI.]] [[A non-cited violation (]]
NCV)
associated with this issue was documented in Section
: [[IR]] [[19 of]]
NRC integrated inspection
report 05000352/2007003 and 05000353/2007003. Exelon documented this issue and
its corrective actions in IR 620861. The review determined that Unit 1 was not affected.
The inspectors reviewed the corrective actions, including revised procedures, and found
no additional findings or unresolved issues. The documents reviewed are listed in the
Attachment. This
: [[LER]] [[is closed.4]]
OA6Meetings, Including ExitExit Meeting SummaryOn October 15, 2007, the resident inspectors presented the inspection results toMr. E. Callan and other members of his staff. The inspectors confirmed that proprietary
information was not included in the inspection report.
: [[ATTACH]] [[]]
: [[MENT]] [[:]]
: [[SUPPLE]] [[]]
: [[MENTAL]] [[]]
: [[INFORM]] [[]]
: [[ATION]] [[A-1AttachmentSUPPLEMENTAL]]
: [[INFORM]] [[]]
: [[ATIONK]] [[EY]]
: [[POINTS]] [[]]
: [[OF]] [[]]
: [[CONTAC]] [[]]
TExelon Generation CompanyC. Mudrick, Site Vice PresidentE. Callan, Plant Manager
D. DiCello, Radiation Protection Manager
: [[R.]] [[Dickinson, Director Engineering]]
: [[J.]] [[Berg, System Manager,]]
: [[HPCI]] [[and]]
: [[RC]] [[]]
IC
J. George, System Manager, Remote Shutdown Panel
M. Gift, System Manager, Radiation Monitoring Systems
R. Gosby, Radiation Protection Technician, Instrumentation
R. Harding, Engineer, Regulatory Assurance
R. Kreider, Manager, Regulatory Assurance
D. Malinowski, Simulator Instructor
: [[B.]] [[Tracy, System Manager]]
: [[P.]] [[Tarpinian,]]
PRA Engineer
D. Boylan, Summer Readiness Coordinator
: [[R.]] [[Newmaster, Manager - Emergency Preparedness, Limerick]]
: [[J.]] [[Broillet, Operations Shift Manager]]
: [[LIST]] [[]]
: [[OF]] [[]]
: [[ITEMS]] [[]]
: [[OPENED]] [[,]]
: [[CLOSED]] [[,]]
: [[AND]] [[]]
DISCUSSEDClosed05000353/2007-001-0LERScram Discharge Volume Vent and DrainValves Failed Open due to Clearance
Tagging Error (Section 40A3.2)05000353/2007-002-0LERValid Actuation of Main Condenser LowVacuum Isolation Logic During Outage
(Section 40A3.3) 05000353/2007-003LERAutomatic Actuation of the ReactorProtection System at Power (Section
40A3.4) DiscussedNone
A-2AttachmentLIST
: [[OF]] [[]]
: [[DOCUME]] [[NTS]]
: [[REVIEW]] [[]]
EDSection 1R01:  Adverse Weather ProtectionProceduresOP-AA-108-107-1001, "Station Response to Grid Capacity Conditions," Revision 2S32.3.A, "Main Generator Inspection During Heavy Grid Load," Revision 7Section 1R04: Equipment AlignmentProceduresTechnical Specification 3/4 8.1, "A.C. Sources"S92.9.N, "Routine Inspection of the Diesel Generators," Revision 53
1S46.1.A (COL), "Valve and Breaker Alignment for Start-up of the Control Rod Drive Hydraulic
Supply System for Service"
: [[ST]] [[-6-048-230-1, "]]
SLC Pump, Valve, and Flow Test"
S49.3.A, "RCIC Fill and Vent," Revision 17
Troubleshooting, Rework, and Testing Control Form,
: [[TRT]] [[No. 07-174,]]
RCIC Fill and VentSection 1R05: Fire ProtectionProceduresARC-MCR-006 B1L, Fire Alarm Response Card, Revision 2F-A-452, "Unit 1 Static Inverter Room, Fire Area 20," Revision 7
F-A-453, "Unit 2 Static Inverter Room, Fire Area 20," Revision 4
F-A-533, "Control Room 533 and Peripheral Rooms 530 to 535 (EL. 269) Fire Area 24," Revision 10F-A-619, "Control Structure Fan Room (EL. 304) Fire Area 27," Revision 6
F-A-624, "Standby Gas Treatment Area Rooms 624 & 625, Fire Area 28," Revision 6
F-D-311D, "D14 Diesel Generator Room and Fuel Oil and Lube Oil Tank Room Rooms 311Dand 312D (EL. 217) Fire Area 82," Revision 5F-T-328, "Unit 1 Air Compressor,
: [[EHC]] [[Power Unit, and Turbine Lube Oil Storage Tank AreasRooms 328, 330, and 331 (]]
: [[EL.]] [[217) Fire Area 93," Revision]]
: [[5OP]] [[-]]
AA-201-003, "Fire Drill Performance," Revision 8
: [[SE]] [[-8, "Fire," Revision 31]]
: [[ST]] [[-6-022-551-0, "Fire Drill," Revision 8, conducted on 9/26/07Issue Reports and Action Requests (]]
: [[AR]] [[s)IR 676038, "Fire Brigade Member]]
: [[EO]] [[Key Ring"A1261436, "Evaluate Propping Open of Doors"Miscellaneous]]
: [[UFSAR]] [[Appendix]]
: [[9AS]] [[ection 1R06: Flood Protection MeasuresProcedures]]
SE-4, "Flood," Revision 5SE-4-1, "Reactor Enclosure Flooding," Revision 8
A-3AttachmentIssue Reports and Action RequestsIR 634795, "Floor Drain Clogged in U/1
: [[HPCI]] [[Room"Miscellaneous]]
: [[BLP]] [[-31981, "Moderate Energy Pipe Break (MEPB) Analysis," dated February 1984NPB-14, "Moderate Energy Line Break," Revision 4]]
: [[NPB]] [[-32, "Flooding of]]
: [[ECCS]] [[Compartments from the Suppression Pool," Revision]]
: [[3NPB]] [[-33, "Moderate Energy Pipe Break Report," Revision 3Section 1R11: Licensed Operator Requalification ProgramProcedures]]
EOP T-101, "RPV Control," Revision 20 EOP T-103, "Secondary Containment Control," Revision 17
: [[EOP]] [[T-112, "Emergency Blowdown," Revision 12]]
: [[EOP]] [[T-270, "Terminate and Prevent injection into]]
: [[RPV]] [[," Revision 12Section 1R12: Maintenance EffectivenessProceduresER-AA-310, "Implementation of the Maintenance Rule," Revision]]
: [[6ER]] [[-]]
: [[AA]] [[-310-1004, "Maintenance Rule - Performance Monitoring," Revision 5]]
: [[ER]] [[-]]
: [[AA]] [[-310-1003, "Maintenance Rule - Performance Criteria Selection," Revision 3]]
: [[ER]] [[-]]
: [[AA]] [[-310-1005, "Maintenance Rule - Dispositioning Between (a)(1) and (a)(2)," Revision 5]]
: [[ER]] [[-]]
: [[LG]] [[-310-1010, "Maintenance Rule Implementation," Revision 7]]
: [[ER]] [[-]]
: [[AA]] [[-310, "Implementation of the Maintenance Rule," Revision 6Issue Reports and Action RequestsIR 483496, "TECW Unavailability Issues"IR 637270, "Possible Maintenance Rule (a)(1) for Excessive]]
: [[TE]] [[]]
: [[CW]] [[System Outage Window"]]
: [[IR]] [[642006, "2B]]
: [[TECW]] [[Heat Exchanger Unavailability Hours Exceeded"]]
: [[IR]] [[667927, "Document Unit 2]]
HPCI Maintenance Rule (a)(1) Determination"
: [[IR]] [[506692, "Points 3 & 5 Failing"]]
: [[IR]] [[546231, "1A Recombiner Valve]]
: [[FV]] [[-DO-101A Failed to Open"]]
: [[IR]] [[551504, "1A Post]]
: [[LOCA]] [[Recombiner]]
: [[MR]] [[ule]]
FF (A)(1) Determination"MiscellaneousMaintenance Rule Expert Panel Meeting Minutes, dated 11/01/2006, 11/30/2006Maintenance Rule Expert Panel Meeting Minutes, dated 09/14/2000, 02/15/2001, 04/20/2006,
06/19/2007Section 1R13: Maintenance Risk Assessments and Emergent Work ControlProceduresER-AA-600-1045, "Risk Assessments of Missed or Deficient Surveillances," Revision 0S07.6.A, "Placing Alternate Steam Jet Air Ejector In Service," Revision 27
: [[ST]] [[-2-041-661-1, "Safety Relief Valves - Safety Relief Valve Position Indicators Functional Test,"Revision 12Issue Reports and Action Requests]]
IR 598489, "D11 - Adjust Voltage Regulator Droop to 3% - 5%"
A-4AttachmentIR 601471, "ISI Inspection Volume for Code Case N-435"IR 649698, "Incorrect Interpretation of
: [[AS]] [[]]
: [[ME]] [[Code Case N-435-1"]]
: [[IR]] [[657596, "2B Reactor Recirculation]]
: [[MG]] [[Set Runback to Min Speed"]]
: [[IR]] [[668047, "Large]]
VAR Swings During D12 D/G/ Run"IR 674591, "SRV 'D' Position Indicator Functional Test Failed"
A1456726, "Excursion in
: [[KVAR]] [[and]]
KW"
A1600437, "D12 Voltage Regulator VAR Swings When Paralleled to Offsite"
A1628762, "IR for Generation of Activity to Swap Unit
: [[2 SJ]] [[]]
AE"
A1631597, "Repair/Replace/Recal Loop Component," Dated 09/24/2007MiscellaneousOperator Logs dated 07/13/2007Limerick Generating Station On-Line Work Schedule, 09/14/2007-09/16/2007Section 1R15: OperabilityIssue Reports and Action RequestsIR 060981, "HPCI Turbine Steam Supply Valve Position Relay Contacts Failed"IR 101384, "Inappropriate Conclusions in Disp
: [[PEP]] [[I0012531/]]
: [[CR]] [[00060981"]]
: [[IR]] [[641784, "]]
: [[HPCI]] [[Aux Oil Pump Did Not Stop per PV&F"]]
: [[IR]] [[642617, "]]
: [[HV]] [[-055-2F006 Failed to Stroke Open"]]
: [[IR]] [[658690, "Unit 2]]
: [[RCIC]] [[OOS/Gross Fail Alarm"]]
: [[IR]] [[658931, "]]
: [[RCIC]] [[Pump Suction HI Press Alarm Came in While Swapping Suction Valves"]]
: [[IR]] [[658950, "]]
HPCI Oil Pressure Lower Than Desired Band"
A1626638, "HPCI Oil Pressure Lower Than Desired Band"
: [[IR]] [[651187, "]]
: [[HPCI]] [[Higher than Normal Unit]]
: [[1 HP]] [[]]
: [[CI]] [[Pump Room Temperature"]]
: [[IR]] [[664065, "Unit 2 Recirculation Pump #2 Seal Pressure Drop"MiscellaneousLimerick Generating Station]]
UFSAR Section 6.3LEAM-0008, "HPCI Flow to RPV w/Single Discharge Path Open," Revision 0
M-48-12, "SLCS Boron Injection Delay Time," Revision 4
M-55-10, "HPCI Line Sizing Check," Revision 4
M-55-26, "ATWS 3A
: [[HPCI]] [[Flow Split Calculation to Size a Flow Orifice for Branch to CoreSpray," Revision 6]]
: [[ECR]] [[]]
: [[LG]] [[01-01152, "]]
: [[HPCI]] [[Failed Injection Valve - Provide Quality Docs"Section 1R19: Post Maintenance TestingProceduresST-2-042-638-2, "ATWS - Reactor Vessel Water Level - Low Low, Functional Test," Revision]]
: [[12ST]] [[-6-051-231-2, "A]]
: [[RHR]] [[Pump, Valve and Flow Test," Revision 52]]
: [[ST]] [[-6-012-231-0, "A Loop]]
: [[RHRSW]] [[Pump, Valve and Flow Test", Revision 54]]
: [[ST]] [[-6-048-230-1, "]]
: [[SLC]] [[Pump, Valve and Flow Test", Revision 32]]
: [[ST]] [[-6-107-201-0,"]]
IST Valve Stroke for New Baseline," Revision 4
M-C-792-001, "Fairbanks Morse Opposed Piston Diesel Engine Examination and GeneralMaintenance," Revision 4Issue Reports and Action RequestsIR 338368, "Unit
: [[2 RCIC]] [[Small Packing Leak from]]
: [[HV]] [[-049-2F008]]
: [[OUTBD]] [[]]
: [[PCIV]] [["IR 381319, "Unit]]
: [[2 RCIC]] [[]]
HV-049-2F008 Packing Leak"
A-5AttachmentIR 654021,"D22 Diesel Lube Oil Circ Pump Making Excess Noise"IR 654041, "Dual Indication for HV-51-2F024A During Stroke Close"
IR 663431, "D21: Brush Holder Cable Replacement Not Identical to Original"
IR 664060, "D21 Diesel Rapid Shutdown Due to Cylinder Leak"
IR 664291, "D21 Emergency Stop Alarm Failed to Annunciate"
IR 676024, "Indicating Lights did not Illuminate"
A1178453, "Disassemble and Inspection 20" Manual Check Valve, 012-0001C"
A1624433, "Replace
: [[RRCS]] [[]]
HPII/HPOI Cards"A1628140, "D21 Over Excitation During Break-In Run"
A1628023, "Alarms on D21 Still Annunciated and Will Not Clear"
A1628302, "D21 Diesel Rapid Shutdown Due to Cylinder Leak"
A1630245, "Unit
: [[2 RCIC]] [[Steam Line Outboard]]
PCIV"Work OrdersR1005988, "D21 24 Month Diesel Inspection Per M-C-792-001"
MiscellaneousLimerick Generating Station On-Line Work Schedule 08/23/2007-08/26/2007Operator Logs dated 08/23/2007
Safety Relief Valve Technical Specification Accident Monitoring Instrumentation Table 3.3.7.5-1Section 1R22: Surveillance TestingProceduresST-2-051-802-2, "Division
: [[2 LPCI]] [[System Response Time Testing," Revision 8]]
: [[ST]] [[-2-055-810-1, "HPCI System Response Time Testing," Revision 11, completed 09/18/2007]]
: [[ST]] [[-6-055-230-1, "]]
: [[HPCI]] [[Pump, Valve, and Flow Test," Revision 65, completed 09/18/2007]]
: [[ST]] [[-6-092-314-2, "D24 Diesel Generator Slow Start Operability Test Run," Revision 61,completed 07/16/07]]
: [[ST]] [[-6-107-790-2, "Control Rod Scram Timing," Revision 11, completed 09/20/2007Issue Reports and Action RequestsA1614302, "U2]]
: [[HCU]] [[46-47 Has No Full Out Position Indication on Full Core Display"]]
: [[IR]] [[671836, "Blue Scram Light Failed to Light During]]
: [[ST]] [[-6-107-790-2"Section 1R23: Temporary Plant ModificationsProcedures]]
CC-AA-112, "Temporary Configuration Changes," Revision 12S43.0.C, "Clearing an Electrical or Mechanical Stop," Revision 18MiscellaneousTRT-D7-164, "Install 1B Reactor Recirculation Pump Motor Generator Temporary Mechanical Stop"C0221920, "Install Temporary Mechanical High Speed Stop in XY-M1-1S001B"
Limerick Generating Station
: [[UFS]] [[]]
AR Section 5.4
Limerick Generating Station Technical Specifications 3/4.4.1Issue Reports and Action RequestsIR 631119, "1B Recirc Pump Speed Changes"IR 654530, "Emergent
: [[PRA]] [[- Need New]]
AR Created to Install Travel Limiter"
A1616738, "1B Recirc Pump Speed Changes"
A-6AttachmentA1625008, "Need New
: [[AR]] [[Created to Install Travel Limiter"Section 1]]
EP6: Drill EvaluationProceduresEOP T-117, "Level/Power Control," Revision 15EOP T-104, "Radioactivity Release Control," Revision 12
: [[EOP]] [[T-103, "Secondary Containment Control," Revision 17]]
: [[EOP]] [[T-270, "Terminate and Prevent Injection Into]]
: [[RPV]] [[," Revision 12]]
: [[EP]] [[-]]
: [[AA]] [[-122, "Drills and Exercises," Revision 7]]
: [[EP]] [[-]]
: [[AA]] [[-122-F-01, "Drill and Exercise Evaluation Criteria," Revision B]]
: [[EP]] [[-]]
: [[AA]] [[-122-1001, "Drill and Exercise Scheduling, Development, and Conduct," Revision 8]]
: [[EP]] [[-]]
: [[AA]] [[-122-1002-F-02, "Drill and Exercise Objective Evaluation Data Tables," Revision B]]
: [[LS]] [[-]]
AA-120, "Issue Identification and Screening Process," Revision 7
T-103, "Secondary Containment Control," Revision 17MiscellaneousIR 437320IR 670538
Limerick [EP] Training Drill Series Evaluation Report, dated 07-31-2007
: [[LS]] [[]]
: [[ES]] [[-8020, "Licensed Operator Training Simulator Evaluation Scenario," Revision 0]]
: [[NRC]] [[]]
: [[IR]] [[50-352&353/2005009Section]]
: [[4OA]] [[1: Performance Indicator (]]
: [[PI]] [[) VerificationProceduresS92.6.N, "Diesel Oil Storage Tank Lineup to Fill Other than its Associated Day Tank," Revision 10Issue Reports and Action RequestsIR 556902, "Minor Leakby of 049-2F014 Discovered During]]
: [[ST]] [[-2-049-601-2"]]
: [[IR]] [[565800, "HV-049-1F019]]
: [[RCIC]] [[Min Flow Shows Dual Indication at 600]]
: [[GPM]] [["]]
: [[IR]] [[620861, "]]
: [[GP]] [[-18 Review]]
: [[HPCI]] [[/]]
: [[RCIC]] [[Oscillations"]]
: [[IR]] [[628573, "]]
: [[RCIC]] [[]]
: [[MOV]] [[Overload or Power Loss]]
: [[DS]] [[14"]]
: [[IR]] [[628579, "Inadvertent]]
: [[RCIC]] [[OOS Annunciator"]]
: [[IR]] [[628600, "2]]
DA-09 Tripped on Thermals"
: [[IR]] [[642618, "Valve Stroke Time Outside Acceptable Range"]]
: [[IR]] [[652846, "]]
RCIC Overspeed Test Potentiometers Possibly Not Locked"
A1238085, "Determine if
: [[HP]] [[]]
CI is Operable With Temperature Instrumentation Installed"
A1295250, "FI-49-1R600-1 Spiking"
A1304397, "Revise the
: [[ML]] [[-008 Spec to Correctly Reflect the Safety Classification of the]]
: [[RCICM]] [[in Flow Line"MiscellaneousNEI 99-02, "Regulatory Assessment Performance Indicator Guideline," Revision 5Reactor Oversight Program]]
: [[MS]] [[]]
: [[PI]] [[Bases Document, Limerick Generating Station, Revision 1]]
: [[MSPI]] [[Derivation Reports for]]
: [[HPCI]] [[,]]
: [[RCIC]] [[, and]]
EDGs
Operator Logs dated 07/01/2007 through 07/31/2007
Maintenance Rule Failure Reports for
: [[HPCI]] [[,]]
: [[RCIC]] [[, and EDGs]]
: [[LG]] [[01-00170, "Classification of the]]
RCIC Min Flow Line"Section 4OA2: Other
A-7AttachmentIssue Reports and Action RequestsA16106882C-P501 Packing Leakoff Excessive (Complete)A16159402C Circ Pump Step Change in Vibration
A1620985Spray Pond Level/Temp Alarming Before Setpoints Reached
A16219922C-P501 Excessive Packing Leakage (Complete)
A1622672Control Rod 22-35 Temp at 305 Deg F
A1628676Spray Pond Hi Temp Alarms Early
C02212742C-P501-DR Inspect or Replace Motor Bearings
: [[IR]] [[6120832C-P501 Packing Leakoff Excessive]]
: [[IR]] [[612647Drive Mechanism Temperature for]]
HCU 30-35 is @429 Degrees F
IR 6275952C Circ Pump Surge Capacitor Damaged
IR 6289652C Circ Pump Step Change in Vibration
IR 639934"Spray Pond Lo Level/Hi Temp" Alarm Locked In
IR 643596Spray Pond Level/Temp Alarming Before Setpoints Reached
IR 6454662C-P501 Excessive Packing Leakage
IR 648107Control Rod 22-35 Temp at 305 Deg F (Completed)
: [[IR]] [[649388Hairline Crack Identified on Yoke]]
: [[IR]] [[6498062C-P501-]]
DR Temp Cooling
IR 654068Hairline Crack Identified on Yoke
IR 654070Hairline Crack Identified on Yoke
IR 665262Spray Pond Hi Temp Alarms Early
IR 6723152C-P501 High Packing Leak OffOther DocumentsPlant Health Committee System Presentation: Circ Water, June, 2007Plant Health Committee System Presentation: Control Rod Drive Supply, June, 2007
Plant Health Committee System Presentation: EDG, June, 2007
Plant Health Committee System Presentation:
: [[RHR]] [[]]
: [[SW]] [[, June, 2007]]
: [[SH]] [[]]
: [[IP]] [[Chronic Problem Report: Circ Water, June, 2007]]
: [[SHIP]] [[Chronic Problem Report:]]
EDG, June, 2007
System Health Overview Report: Circ Water, June, 2007
System Health Overview Report: Control Rod Drive Supply, June, 2007
System Health Overview Report: EDG, June, 2007
System Health Overview Report:
: [[RHR]] [[]]
SW, June, 2007
System Health Overview Report: Circ Water, Sept, 2007
System Health Overview Report: Control Rod Drive Supply, Sept, 2007
System Health Overview Report: EDG, Sept, 2007
System Health Overview Report:
: [[RHRSW]] [[, Sept, 2007Section 4]]
: [[OA]] [[3: Event FollowupProceduresOP-LG-109-101-1001, "Limerick System Specific Tagging Guides," Revision 15Issue Reports and Action RequestsIR 601910, "Drainage System Clogged"IR 602042, "Unit 2 SDV Vent/Drain Valves Open With Scram Signal Present"]]
: [[IR]] [[602921, "Division 1 and 4]]
MSIV Isolation Logic Alarms"
A-8AttachmentMiscellaneousLER 2007-001, "Scram Discharge Volume Vent and Drain Valves Failed Open Due to ClearanceTagging Error"LER 2007-002, "Valid Actuation of Main Condenser Low Vacuum Isolation Logic During Outage"
: [[LER]] [[2007-003, "Automatic Actuation Of The Reactor Protection System at Power"]]
: [[LIST]] [[]]
: [[OF]] [[]]
: [[ACRONY]] [[MSADAMSAgencywide Documents Access Management SystemARaction request]]
: [[ASM]] [[]]
: [[EA]] [[merican Society of Mechanical Engineers]]
: [[CA]] [[]]
: [[PC]] [[orrective Action Program]]
: [[CF]] [[]]
RCode of Federal Regulations
CRDcontrol rod drive
EDGemergency diesel generator
EHCelectro-hydraulic control
: [[EP]] [[emergency preparedness]]
: [[ER]] [[]]
: [[OE]] [[mergency Response Organization]]
: [[HP]] [[]]
CIhigh pressure coolant injection
IRissue report
kVkilo volt
: [[LE]] [[]]
: [[RL]] [[icensee Event Report]]
: [[LO]] [[]]
: [[CA]] [[loss of coolant accident]]
: [[MS]] [[]]
IVmain steam isolation valve
: [[NCV]] [[non-cited violation]]
: [[NE]] [[]]
: [[IN]] [[uclear Energy Institute]]
: [[NR]] [[]]
CNuclear Regulatory Commission
OAother activities
: [[PAR]] [[protective action recommendation]]
: [[PAR]] [[]]
SPublicly Available Records
: [[PI]] [[performance indicator]]
: [[P&]] [[]]
IDpiping and instrumentation drawing
: [[PMT]] [[post-maintenance test]]
: [[RC]] [[]]
ICreactor core isolation cooling
: [[RHR]] [[residual heat removal]]
: [[RR]] [[]]
: [[CS]] [[redundant reactivity control system]]
: [[SC]] [[]]
BAself-contained breathing apparatus
: [[SDV]] [[scram discharge volume]]
: [[SH]] [[]]
IPsystem health indicator program
SSC structure, system, component
: [[TS]] [[technic al specification]]
: [[UFS]] [[]]
: [[AR]] [[updated final safety analysis report]]
}}
}}

Latest revision as of 07:14, 22 December 2019

IR 05000352-07-004, 05000353-07-004; on 07/01/07-09/30/07; Limerick Generating Station, Units 1 and 2; Routine Integrated Report
ML073180045
Person / Time
Site: Limerick  Constellation icon.png
Issue date: 11/13/2007
From: Paul Krohn
Reactor Projects Region 1 Branch 4
To: Pardee C
Exelon Generation Co, Exelon Nuclear
KROHN, PG
References
IR-07-004
Download: ML073180045 (25)


Text

November 13, 2007

SUBJECT:

LIMERICK GENERATING STATION - NRC INTEGRATED INSPECTION REPORT 05000352/2007004 AND 05000353/2007004

Dear Mr. Pardee:

On September 30, 2007, 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 October 15, 2007, with Mr. E. Callan 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.

Based on the results of this inspection, no findings of significance were identified.

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 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 05000352/2007004 and 05000353/2007004 w/Attachment: Supplemental Information

SUMMARY OF FINDINGS

IR 05000352/2007-004, 05000353/2007-004; 07/01/2007 - 09/30/2007; Limerick Generating

Station, Units 1 and 2; Routine Integrated Report.

The report covered a three-month period of inspection by resident inspectors and announced inspections by reactor inspectors. 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

No findings of significance were identified.

Licensee-Identified Violations

None.

iii

REPORT DETAILS

Summary of Plant Status

Unit 1 began this inspection period operating at full rated thermal power. On August 16, 2007, reactor power was reduced to 20 percent and the main generator was removed from service to repair the generator output number 11 disconnect switch. On August 17, 2007, the disconnect switch repairs were completed and the main generator was returned to service. Unit 1 returned to 100 percent power on August 18, 2007. With the exception of a planned end of summer load drop to 85 percent power on September 8, 2007, Unit 1 remained at full power for the remainder of the period.

Unit 2 began this inspection period operating at full rated thermal power. On August 6, 2007, reactor power decreased to 75 percent due to an unplanned speed reduction on the 2B reactor recirculation pump. The pump speed change was due to a recirculation motor generator electronic card failure. The card was replaced and Unit 2 was returned to 100 percent power later in the day. With the exception of a planned end of summer load drop to 60 percent power on September 15, 2007, Unit 2 remained at full power for the remainder of the period.

REACTOR SAFETY

Cornerstones: Initiating Events, Mitigating Systems, and Barrier Integrity

1R01 Adverse Weather Protection (71111.01 - 1 system sample)

a. Inspection Scope

The inspectors evaluated Exelons preparations and protection for summer weather. On July 10, 2007, the inspectors walked down Unit 1 and Unit 2 main generators and main transformers during hot weather and a grid heavy load voltage condition. 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 four partial walkdowns of plant systems to verify the operability of redundant or diverse trains and components when safety 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 systems:

.2 Complete System Walkdown

The inspectors conducted one complete walkdown of the Unit 1 and Unit 2 Control Rod Drive (CRD) systems to verify functional capability of the system. The inspectors used plant TS, Exelon operating procedures, P&IDs, the UFSAR, and past surveillance tests as guidance for conducting the complete system walkdown. The inspectors reviewed the alignment of system valves, position of electrical breakers and settings of the system flow controller to ensure proper system configuration as described in plant procedures and drawings. During the walkdown, the inspectors evaluated the material condition and general housekeeping of the system and open issue reports associated with the system.

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

.

b. Findings

No findings of significance were identified.

1R05 Fire Protection

.1 Fire Protection - Tours

a. Inspection Scope

The inspectors conducted a tour of the eight 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 Exelons fire plan. The documents reviewed are listed in the Attachment. The inspectors performed the following samples:

  • Main Control Room and peripheral rooms;
  • Unit 1 Refuel Floor;
  • Unit 2 Refuel Floor;
  • Unit 1 and Unit 2 Static Inverter compartments;
  • Control Room Structure fan room, Elevation 304; and
  • Unit 1 D14 Diesel Generator Room.

.2 Fire Protection - Drill Observation

a. Inspection Scope

The inspectors observed one unannounced fire drill conducted in the Unit 1 air compressor, electro-hydraulic control (EHC) power unit, and turbine lubricating oil storage tank area on September 26, 2007. The inspectors observed the drill to evaluate the readiness of the plant fire brigade to fight fires. The documents reviewed are listed in the Attachment. Specific attributes evaluated were:

  • Proper donning of fire fighting turnout gear and self-contained breathing apparatus (SCBA);
  • Proper use and layout of fire hoses;
  • Employment of appropriate fire fighting techniques;
  • Sufficient fire fighting equipment brought to the scene;
  • Effectiveness of fire brigade leader communications, command, and control;
  • Search for victims and propagation of fire into other plant areas;
  • Smoke removal operations;
  • Utilization of pre-planned strategies;
  • Adherence to the pre-planned drill scenario; and
  • Drill objectives.

b. Findings

No findings of significance were identified.

1R06 Flood Protection Measures

Internal Flooding

a. Inspection Scope

The inspectors reviewed documents and inspected structures, systems, and components (SSCs) relative to the adequacy of internal flood protection measures for the Unit 1 HPCI room. The inspectors performed walkdowns of the relevant areas to verify the adequacy of flood mitigation doors and barriers, drainage systems, and other flood protection features. The documents reviewed are listed in the Attachment.

b. Findings

No findings of significance were identified.

1R11 Licensed Operator Requalification Program

Resident Inspector Quarterly Review (1 sample)

a. Inspection Scope

On August 28, 2007, the inspectors observed a licensed operator requalification simulator scenario. The scenario included a simulated spurious Division 1 Loss of Coolant Accident (LOCA) signal with failure of the D11 EDG to start and an unisolable reactor water cleanup leak, which resulted in a manual scram and emergency blowdown.

The inspectors observed the performance of two operating crews responding to the same scenario. The inspectors assessed licensed operator performance, including operator 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 simulation. 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 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 Attachment. The inspectors performed the following samples:

  • 1A post LOCA recombiner maintenance rule (a)(1) determination;
  • 2B Turbine Enclosure Cooling Water heat exchanger system outage window; and

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 risk assessments for the following issues:

  • Unit 1 HPCI room temperature high;
  • Unit 2 Reactor Recirculation Motor Generator runback to minimum speed;
  • Unit 1 Main Generator Disconnect high temperatures;
  • Unit 1 Main Generator Disconnect phases A and C jumper installation;
  • Large VAR (Volt-Ampere Reactive) swings during EDG run;

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 (IRs) to verify that Exelon identified and corrected deficiencies associated with operability evaluations. The documents reviewed are listed in the Attachment. The inspectors reviewed operability evaluations for the following components:

  • Unit 2 HPCI HV-055-2F006;
  • Unit 1 HPCI Room Cooler;
  • Unit 2 HPCI Oil Pressure; and
  • Unit 2B Reactor Circulation Pump mechanical seal.

b. Findings

No findings of significance were identified.

1R19 Post-Maintenance Testing

a. Inspection Scope

The inspectors reviewed the eight 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 applicable 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 Attachment. The inspectors reviewed post-maintenance tests for the following systems and components:

  • 2A RHR Suppression Pool Cooling Valve;
  • D21 Diesel Generator;
  • Unit 2 Redundant Reactivity Control System (RRCS).

b. Findings

No findings of significance were identified.

1R22 Surveillance Testing

a. Inspection Scope

The inspectors witnessed the performance and reviewed test data for five surveillance tests that are associated with selected 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 the surveillance tests for the following systems and components:

  • Unit 2 D24 EDG;
  • Unit 2 Division 2 Lower Pressure Coolant Injection;

b. Findings

No findings of significance were identified.

1R23 Temporary Plant Modifications

a. Inspection Scope

The inspectors reviewed and compared the temporary modification listed below with the UFSAR and TS to verify that the modification did not affect operability or availability of the Unit 1 reactor recirculation motor generator. 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 appropriate revisions were made to reflect the temporary configuration change. Additionally, the inspectors evaluated the adequacy of proposed testing upon removal of the change. The documents reviewed are listed in the

. The inspectors performed the following sample:

b. Findings

No findings of significance were identified.

Cornerstone: Emergency Preparedness (EP)

1EP6 Drill Evaluation

.1 General Emergency Classification due to Simulated Fuel Failure Coincident with Failed

Open Main Steam Line Isolation Valves

a. Inspection Scope

On June 19, 2007, the inspectors observed an EP training drill in the control room simulator. The inspectors assessed Exelon's emergency response organization's (ERO)implementation of the Limerick emergency plan and implementing procedures, and the ERO's response to simulated degraded plant conditions to identify weaknesses and deficiencies in classification, notification, and protective action recommendation (PAR)development activities. In addition, the inspectors assessed licensed operator performance required to ensure the safe operation of the reactor and the protection of the nuclear fuel and primary containment barriers. The inspectors reviewed Exelons training evaluators' critiques and the formal critique report, dated July 31, 2007, associated with the EP drill, to evaluate Exelon's identification of weaknesses and deficiencies. The inspectors compared inspector observed weaknesses with those identified in Exelon's formal drill critique to verify whether Exelon adequately identified weaknesses and deficiencies at an appropriate threshold. The documents reviewed are listed in the Attachment.

b. Findings

No findings of significance were identified.

.2 Site Area Emergency Classification Due to a Simulated Reactor Coolant System Leak in

the Reactor Building

a. Inspection Scope

The inspectors observed a licensed operator requalification simulator exercise evaluation to identify the timing and adequacy of classification, notification, and PAR development activities. During the simulator evaluation, the inspectors reviewed checklists and forms used for classification and notification activities, and compared them to the criteria in Exelons Emergency Plan, EP-MA-114-100-F-01, State/Local Event Notification Form, and supporting procedures. The documents reviewed are listed in the Attachment.

b. Findings

No findings of significance were identified.

OTHER ACTIVITIES

4OA1 Performance Indicator (PI) Verification

Inspection Scope The inspector sampled Exelons submittal of the performance indicators listed below to verify the accuracy of the data recorded from the third quarter of 2006 through the third quarter of 2007. 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 main control room logs, issue reports, power history curves, work orders, and system derivation 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)

Cornerstone: Mitigating Systems (6 samples)

b. Findings

No findings of significance were identified.

4OA2 Identification and Resolution of Problems

Review of Items Entered into the Corrective Action Program (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 performed a screening of all items entered into Limericks CAP. The inspectors accomplished this by reviewing the description of each new issue report and accessing Exelons computerized database. The documents reviewed are listed in the Attachment.

b. Findings

No findings of significance were identified. The inspectors observed that issues selected for review were appropriately categorized and prioritized in accordance with Exelons corrective action process.

4OA3 Event Followup

.1 Unit 1 Main Generator Output Switchyard Disconnect Removal from Service due to High

Temperature

a. Inspection Scope

On August 16, 2007, the inspectors responded to the plant due to a high temperature on the Unit 1 main generator output disconnect. The inspectors discussed the switchyard disconnect problem with operations personnel, engineering personnel, and Exelon management to gain an understanding of Exelons response and follow-up actions. The inspectors reviewed troubleshooting activities, the disconnect temperature surveillance monitoring, and the planned actions to repair and correct the disconnect high temperature condition.

The number 11 disconnect is located on the output of the Unit 1 main transformers and is physically located in the Unit 1 220 kilovolt (kV) switchyard. The disconnect is comprised of three individual disconnects and associated bus bars. The disconnect B phase temperature reached a maximum value of 375 degrees Celsius and resulted in reactor power reductions to lower the temperature. The location of the elevated temperature was at the movable hinged section of the disconnect. The "A" and "C" phase temperatures were 95 to 100 degrees Celsius. The B phase high temperature was discovered during ongoing monthly temperature monitoring.

In response to the high temperature, operators reduced reactor power from 100 percent down to 25 percent to reduce the disconnect temperature and support removal of the main generator and disconnect from service to perform repairs. The inspectors observed just-in-time training in the simulator that was given to the operators prior to removing the main generator and disconnect from service. The inspectors also observed the operators removal of the main generator and disconnect from service to support repairs.

After removal from service, the B phase disconnect was rebuilt and tested satisfactorily prior to being returned to service. The main generator was placed back in service and the plant was returned to 100 percent power. The documents reviewed are listed in the

.

b. Findings

No findings of significance were identified.

.2 (Closed) LER 05000353/02007-001, Scram Discharge Volume Vent and Drain Valves

Failed Open Due to Clearance Tagging Error On March 10, 2007, Limerick Unit 2 was in hot shutdown and depressurized to approximately 25 psig for the 2R09 refueling outage. A full scram signal was present and the scram discharge volume (SDV) was isolated, as designed. Operators were in the process of applying a clearance in preparation for planned maintenance on the Reactor Protection System and the scram air header. As part of this clearance, operators removed the Reactor Protection System backup scram fuses which ultimately resulted in the SDV vent and drain valves opening unexpectedly. Water from the SDV began to vent through these open valves into the plant drain system. Station personnel discovered the condition and closed the SDV vent and drain valves, stopping the source of the water. Further investigation by the station determined that the inadvertent opening of the SDV vent and drain valves was due to an improperly written clearance.

A non-cited violation (NCV) associated with this issue was documented in Section 1R20 of NRC integrated inspection report 05000352/2007002 and 05000353/2007002. The inspectors reviewed this LER and did not identify any additional findings of significance.

Exelon documented this event and associated corrective actions in IR 602042. The documents reviewed are listed in the Attachment. This LER is closed.

.3 (Closed) LER 05000353/02007-002, Valid Actuation of Main Condenser Low Vacuum

Isolation Logic During Outage On March 12, 2007, operators were in the process of lowering vacuum on Limerick Unit 2 as part of refueling outage activities in accordance with procedure S07.2.A, Shutdown of the Steam Jet Air Ejector and Breaking Main Condenser Vacuum. During this evolution, the main condenser low vacuum main steam isolation valve (MSIV) isolation logic actuated unexpectedly. Further investigation revealed that due to a procedural execution error, station personnel had only bypassed two of the required four channels of the isolation logic. Even though this resulted in actuation of two channels of logic when vacuum was lowered, no valves actually repositioned since the MSIVs and other affected valves were closed earlier as required by procedure. This failure to comply with procedure S07.2.A constitutes a violation of minor significance that is not subject to enforcement action in accordance with Section IV of the NRCs enforcement policy. The inspectors reviewed this LER and did not identify any additional findings of significance.

Exelon documented this event and associated corrective actions in IR 602921. This LER is closed.

.4 (Closed) LER 05000353/02007-003, Automatic Actuation of the Reactor Protection

System at Power On April 24, 2007, the Unit 2 Reactor Protection System automatically actuated when reactor water level decreased from +35 inches to +12.5 inches. All control rods fully inserted. When reactor level decreased to the low-low level setpoint of -38 inches, both HPCI and RCIC systems initiated and injected into the vessel. HPCI and RCIC were placed in manual mode when flow oscillations were observed on both systems. Both systems were automatically secured when reactor level increased to +54 inches.

Exelons investigation determined that a circuit card in Redundant Reactivity Control System (RRCS) Division 1, channel B spuriously actuated while channel A was in a tripped condition due to planned surveillance testing. This resulted in a feedwater runback. The feedwater runback reduced reactor level as expected.

Exelons investigation determined that HPCI and RCIC flow oscillations were due to flow control loop tuning settings that did not properly account for differences in flow path testing conditions and vessel injection flow conditions. Station personnel replaced and successfully tested the affected RRCS circuit card. In addition the HPCI and RCIC flow controller gain and reset settings were adjusted to be consistent with Unit 1 settings, which are consistent with industry values and similar to previous Unit 2 settings when stable flow was demonstrated during Unit 2 initial startup testing. The procedure for tuning of HPCI and RCIC flow controls was revised to specify the required gain and reset settings.

The inspectors reviewed Exelons apparent cause investigation, Unit 2 TS, and notification requirements. The apparent cause investigation determined that the HPCI and RCIC gain and reset settings were changed during system tuning in May 1999; therefore, this condition existed for approximately 8 years. This resulted in a condition that could have prevented the safety function of Unit 2 HPCI. A non-cited violation (NCV)associated with this issue was documented in Section IR19 of NRC integrated inspection report 05000352/2007003 and 05000353/2007003. Exelon documented this issue and its corrective actions in IR 620861. The review determined that Unit 1 was not affected.

The inspectors reviewed the corrective actions, including revised procedures, and found no additional findings or unresolved issues. The documents reviewed are listed in the

. This LER is closed.

4OA6 Meetings, Including Exit

Exit Meeting Summary

On October 15, 2007, the resident inspectors presented the inspection results to Mr. E. Callan 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
J. Berg, System Manager, HPCI and RCIC
J. George, System Manager, Remote Shutdown Panel
M. Gift, System Manager, Radiation Monitoring Systems
R. Gosby, Radiation Protection Technician, Instrumentation
R. Harding, Engineer, Regulatory Assurance
R. Kreider, Manager, Regulatory Assurance
D. Malinowski, Simulator Instructor
B. Tracy, System Manager
P. Tarpinian, PRA Engineer
D. Boylan, Summer Readiness Coordinator
R. Newmaster, Manager - Emergency Preparedness, Limerick
J. Broillet, Operations Shift Manager

LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED

Closed

05000353/2007-001-0 LER Scram Discharge Volume Vent and Drain Valves Failed Open due to Clearance Tagging Error (Section 40A3.2)
05000353/2007-002-0 LER Valid Actuation of Main Condenser Low Vacuum Isolation Logic During Outage (Section 40A3.3)
05000353/2007-003 LER Automatic Actuation of the Reactor Protection System at Power (Section 40A3.4)

Discussed

None

LIST OF DOCUMENTS REVIEWED