IR 05000260/2005010
| ML050610006 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/01/2005 |
| From: | Ogle C NRC/RGN-II/DRS/EB |
| To: | Singer K Tennessee Valley Authority |
| References | |
| IR-05-010 | |
| Download: ML050610006 (34) | |
Text
rch 1, 2005
SUBJECT:
BROWNS FERRY NUCLEAR PLANT - NRC SAFETY SYSTEM DESIGN AND PERFORMANCE CAPABILITY INSPECTION REPORT NOS.
05000260/2005010 AND 05000296/2005010
Dear Mr. Singer:
On January 28, 2005, the U. S. Nuclear Regulatory Commission (NRC) completed a safety system design and performance capability team inspection at your Browns Ferry Nuclear Plant.
The enclosed report documents the inspection findings which were discussed on January 28, 2005, with Mr. M. Skaggs and other members of your staff. Following completion of additional review in the Region II office, a final exit was held by telephone with Mr. T. Abney of your staff on February 7, 2005, to provide an update on changes to the preliminary inspection findings.
The inspection examined activities conducted under your licenses as they relate to safety and compliance with the Commissions rules and regulations and with the conditions of your licenses. The inspection team reviewed selected procedures and records, observed activities, and interviewed personnel.
Based on the results of the 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 and its enclosure will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of NRC's document system (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Sincerely,
\\RA\\
Charles R. Ogle, Chief Engineering Branch 1 Division of Reactor Safety
TVA 2 Docket Nos.: 50-260, 50-296 License Nos.: DPR-52, DPR-68
Enclosure:
NRC Inspection Report 05000260/2005010 and 05000296/2005010 w/Attachment: Supplemental Information Fredrick C. Mashburn
REGION II==
Docket Nos.: 50-260, 50-296 License Nos.: DPR-52, DPR-68 Report Nos.: 05000260/2005010 and 05000296/2005010 Licensee: Tennessee Valley Authority Facility: Browns Ferry Nuclear Plant, Units 2 & 3 Location: 10833 Shaw Road Athens, AL 35611 Dates: January 10-14, 2005 and January 24-28, 2005 Inspectors: R. Moore, Senior Reactor Inspector (Team Lead)
N. Merriweather, Senior Reactor Inspector R. Cortes, Reactor Inspector P. Fillion, Senior Reactor Inspector M. Thomas, Senior Reactor Inspector L. Mellen, Senior Reactor Inspector C. Peabody, Reactor Inspector in Training Approved by: Charles R. Ogle, Chief Engineering Branch 1 Division of Reactor Safety Enclosure
SUMMARY OF FINDINGS
IR 05000260/2005-010, 05000296/2005-010; 01/10-14/2005 and 01/24-28/2005; Browns Ferry
Nuclear Plant, Units 2 and 3; Safety System Design and Performance Capability Inspection.
This inspection was conducted by a team of inspectors from the NRCs Region II office. No findings of significance were identified. The NRC's program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process, Revision 3, dated July 2000.
NRC-Identified and Self-Revealing Findings
No findings of significance were identified.
Licensee-Identified Violations
None.
REPORT DETAILS
REACTOR SAFETY
Cornerstones: Initiating Events and Mitigating Systems
1R21 Safety System Design and Performance Capability
The team evaluated the capability of installed plant detection and mitigation equipment which provide the high pressure injection function (HPI) at Browns Ferry. The HPI function is provided by the high pressure coolant injection (HPCI) system and the reactor core isolation cooling (RCIC) system.
.1 System Needs
.11 Process Medium
a. Inspection Scope
The team reviewed the availability and reliability of water sources required for the HPI function. These included the condensate storage tanks (CST) for both Units 2 and 3 and the suppression pool for Unit 2. The review included design documentation, drawings, Updated Final Safety Analysis Report (UFSAR), Technical Specifications (TS), corrective actions history, foreign material exclusion history, volumetric calculations for both supplies, calculations of system capacity, HPCI and RCIC pumps net positive suction head (NPSH) available and required, and minimum flow protection on both systems Also, the team reviewed volume calculations to verify vortexing had been properly considered in CST suction piping design. Additionally, the team reviewed the most restrictive portions of the HPCI and RCIC systems to verify that the suppression pool suction strainers were sized accordingly. The team also reviewed the water quality history in the torus to verify there have been no recent conditions of sludge or fouling that could prevent an adequate suction through the strainers.
b. Findings
No findings of significance were identified.
.12 Energy Sources
a. Inspection Scope
The team reviewed design basis documentation (DBDs), drawings, and walked down accessible portions of the HPCI and RCIC systems to verify the steam supply would be available for turbine-pump operation during a design basis event. The team reviewed the HPCI steam supply drain pot flow orifice inspections, corrective action history on the steam traps on the supply and exhaust pipes, and maintenance records to verify that water accumulation conditions in the piping that could cause water hammer and pump overspeed trip events had not occurred. The team reviewed functional valve testing for the HPCI and RCIC turbine exhaust vacuum relief check valves to verify adequacy of acceptance criteria and to verify that the vacuum relief function was being maintained.
The team reviewed test and design documents to verify that the 250 volt direct current (VDC) power supplies were adequate to meet minimum voltage specifications for electrical equipment during and following an event requiring HPI. The surveillance tests which demonstrated the battery chargers have the capacity and capability to recharge the batteries were reviewed. Design torque values for MOVs were reviewed to verify that safety functions (open / closed) based on minimum voltage conditions were adequately tested. Plant simulator demonstrations were utilized to check system response to loss of various 250 V DC power supplies as a means to check that power supplies met the requirements for redundancy. A specific list of components and documents reviewed is included in the Attachment to this report
b. Findings
No findings of significance were identified.
.13 Instrumentation and Controls
a. Inspection Scope
The team reviewed drawings depicting the electrical controls for actuation and shutdown of the turbine driven HPCI and RCIC pumps, including controls for the turbine steam supply valves, CST and suppression pool suction valves, and HPCI/RCIC injection valves, to confirm that the instrumentation and control circuits were consistent with the design basis documents. The team reviewed samples of surveillance test procedures for HPCI and RCIC logic functional testing to confirm that the logic paths were being tested in a manner to adequately demonstrate that the system would perform in accordance with design. The team selected a sample of the process instruments that provide input signals to HPCI and RCIC logic for examination such as reactor vessel level - low low, CST header level-low, suppression pool level-high, HPCI flow indicating controller, RCIC flow indicating controller, and HPCI pressure to verify that the instruments were available to support system operation. The last two completed instrument calibration records were reviewed for the selected instruments to verify that they had been calibrated in accordance with the setpoint documents and calibration procedures. The calibration records were also reviewed to verify that test deficiencies such as out of tolerance conditions were being entered into the corrective action program for evaluation and disposition. The components reviewed are included in the to this report.
b. Findings
No findings of significance were identified.
.14 Operator Actions
a. Inspection Scope
The team reviewed plant operating instructions, including emergency operating instructions (EOIs), abnormal operating instructions (AOIs), alarm response procedures (ARPs), and operating instructions (OIs) that would be used to accomplish the HPI function during the identification and mitigation of a loss of coolant accident (LOCA)event. The team focused on installed equipment and operator actions that could be used to mitigate the event. The review was done to verify that the instructions were consistent with the UFSAR description of a LOCA event and with the Boiling Water Reactors Owners Group (BWROG) Emergency Procedure Guidelines (EPGs), any step deviations were justified and reasonable, and the instructions were written clearly and followed the EOP writers guide. The team held discussions with licensed operators and training instructors, reviewed job performance measures and training lesson plans pertaining to use of HPI equipment during a LOCA event to confirm that training was consistent with the applicable operating instructions.
In addition, the team observed simulation of LOCA scenarios on the plant simulator and walked down portions of applicable instructions to verify that operator training, procedure guidance, and instrumentation were adequate to identify a LOCA event and implement post-LOCA mitigation strategies. The manual operator action times for performance of LOCA mitigation activities related to HPI equipment were reviewed for consistency with accident analyses, EPGs, and operator training. Procedures reviewed are included in the Attachment to this report.
b. Findings
No findings of significance were identified.
.15 Heat Removal
a. Inspection Scope
The team reviewed heat load calculations for the HPCI and RCIC rooms. The team also reviewed the calculated peak temperature responses during a station blackout and high energy line break for these rooms. The team reviewed the vendor manuals, drawings, RCIC and HPCI DBDs, trending information on lube oil temperature profile, and surveillance test documentation to assess the design and performance of the turbine lubricating oil systems on the HPCI and RCIC systems. A specific list of documents reviewed is included in the Attachment to this report.
b. Findings
No findings of significance were identified.
.2 System Condition and Capability
.21 Installed Configuration
a. Inspection Scope
The team performed field walkdowns of HPI equipment and 250 volts direct current (VDC) power supplies to observe the existing conditions and configurations. The team walked down portions of the RCIC and HPCI systems as well as portions of the CST suction source to verify that they were properly aligned for existing plant conditions.
During this walk down, the team compared valve positions with those specified in the system operating procedure line-ups and drawings, and observed the material condition of the plant to verify that it would be adequate to support operator actions and system operation. Equipment examined included the HPCI and RCIC pumps, steam traps and drain pots, system valves, piping, and related components. A specific list of components reviewed is included in the Attachment to this report.
b. Findings
No findings of significance were identified.
.22 Operation
a. Inspection Scope
The team walked down selected portions of HPCI and RCIC operating instructions to check for human factors in the instructions and in the plant; including clarity, accuracy, labeling, lighting, noise, communications, and accessibility. The team also checked HPCI and RCIC system alignments to verify consistency with design and licensing basis assumptions, and the Technical Specifications (TS). These reviews included walkdown of venting procedure actions for the Unit 2 HPCI system and Unit 3 RCIC system.
The team reviewed operating instructions for switching various distribution panels in the 250 V DC system between their normal and alternate sources to evaluate whether these switching operations could result in inadvertent, undesirable consequences such as plant trips, loss of AC power or violation of the divisional separation requirements.
Selected annunciator response procedures and operator rounds procedures were also reviewed from the viewpoint of whether anticipated problems such as grounds would be quickly identified and corrected.
b. Findings
No findings of significance were identified.
.23 Design
a. Inspection Scope
Mechanical Design Review The team reviewed design calculations, specifications, and the UFSAR to verify that system and equipment design functions were appropriately evaluated and maintained.
Surveillance test procedures and equipment monitoring activities were reviewed to verify the design criteria were appropriately translated into the acceptance criteria on the tests.
The team reviewed DBDs, selected piping, selected TSs, PERs, and corrective maintenance history for HPCI and RCIC systems to assess the implementation and maintenance of the systems design basis.
The team reviewed calculations and system configuration to assess the adequacy of the NPSH available to both RCIC and HPCI pumps. In addition, the team reviewed the most restrictive flow conditions in the systems to assess the sizing of the suppression pool strainers. The calculations which established the automatic CST to suppression pool swapover setpoint values were reviewed to verify the vortexing phenomenon was appropriately addressed. System design and configuration was reviewed to assure pump minimum flow requirements and run out protection was provided. A list of documents reviewed is included in the Attachment to this report.
Electrical, Instrumentation and Controls Design Review The team reviewed system flow diagrams, mechanical control drawings, electrical elementary and schematic diagrams, instrument setpoint calculations, instrument scaling documents, as well as calibration procedures and calibration test records to verify that the instrumentation and controls for the RCIC and HPCI pumps were in accordance with design basis documents. Specifically, the team reviewed setpoint calculations for selected process instruments including reactor vessel level-low low, CST header level-low, suppression pool level-high, HPCI flow indicating controller, RCIC flow indicating controller, and HPCI pressure to verify that the calculations included appropriate instrument uncertainties. The last two completed calibration test records were reviewed to confirm that instrument setpoints were established consistent with setpoint calculations. Modifications and component replacements were reviewed to assess potential impact on system design function and capability.
The team reviewed the UFSAR and TS bases to determine the design basis mission time for the 250 VDC batteries which supply power to HPCI and RCIC. The team reviewed battery sizing calculations and voltage calculations. The review included accident scenarios and station blackout. The criteria for review of these calculations were that they were performed using methods delineated in industry standards and demonstrated that adequate power supply capacity would be available to meet design basis scenarios. Particular attention was paid to voltage at key motor operated valves, and it was checked that voltage calculations were coordinated with torque and thrust calculations. In addition, MOVATS test results were reviewed to check that motor inrush currents were consistent with those used in the calculations. Selected samples within the calculation for sizing of thermal overloads were reviewed, and the methodology was compared to industry standards. The criterion for sizing thermal overloads was that they not inadvertently trip to defeat the design basis function of the motor operated valve.
The team inspected installed equipment and recorded nameplate data and setpoint information for selected devices such as thermal overload heaters and molded-case circuit breakers and compared this data to design documents. Design and sensitivity of the ground detection devices were evaluated. The team inspected the battery rooms to verify that ventilation was provided for the battery rooms to handle battery off-gassing.
A list of documents reviewed is included in the Attachment to this report.
b. Findings
No findings of significance were identified.
.24 Testing and Inspection
a. Inspection Scope
The team reviewed performance and post-maintenance testing of pumps and valves to verify that the tests and inspections were appropriately verifying that the assumptions of the licensing and design bases were being maintained and that performance degradation would be identified. The team reviewed service and performance testing and electrical preventive maintenance procedures for the DC batteries. The review was performed in order to verify that specified acceptance criteria were met and that the equipment operation was consistent with the plants licensing and design bases.
The team reviewed selected full flow surveillance test data to ensure that HPCI and RCIC systems injection flow rates remained within system design calculations. The team reviewed documentation of completed surveillance tests and pump head curves to verify that equipment performance was appropriately monitored and maintained consistent with the design and licensing bases. Component testing reviewed included RCIC and HPCI pumps, vacuum relief check valves and feedwater check valves upstream of the injection point of the RCIC and HPCI systems.
The team reviewed valve operability stroke time testing, thrust and torque testing, differential pressure testing, and corrective maintenance records for selected HPCI and RCIC risk significant MOVs, including the steam admission valves and the injection valves for these systems. This review was conducted to verify the availability of the selected valves, adequacy of surveillance testing acceptance criteria, and monitoring of these valves for degradation. The team reviewed completed surveillance instruction test results related to HPCI and RCIC systems venting, and valve position verification, suppression pool level verification, reactor vessel level verification, and condensate storage tank level verification, to verify that testing was being performed in accordance with applicable TS requirements. Test records were reviewed to verify that permissives and interlocks not normally tested during pump testing were verified during periodic surveillance testing. A list of documents reviewed is included in the Attachment to this report.
b. Findings
No findings of significance were identified.
.3 Selected Components
.31 Component Degradation
a. Inspection Scope
The team reviewed maintenance and testing documentation, modifications, performance trending, and equipment history as identified by work orders, PERs, and system health reports to assess the licensees actions to verify and maintain the safety function, reliability and availability of selected components. Equipment reviewed included the RCIC and HPCI pumps, including the booster pump, selected MOVs, vacuum reliefs for both systems, and selected feedwater check valves upstream of injection points for these systems. Field walkdowns were performed of the HPCI and RCIC rooms to assess material condition and identify degraded equipment.
The team also reviewed the potential for common cause failure mechanisms in maintenance. Additionally, the team reviewed in-service trending data for selected components, including the HPCI and RCIC pumps flow profiles, lubricating oil temperatures for the turbine, and vibration testing to verify that the components were continuing to perform within the limits specified by the test and design basis. A specific list of equipment and documents reviewed is included in the Attachment to this report.
The team performed a detailed inspection of two safety related batteries to assess the attributes of plate alignment, growth and color; jar integrity, and post-seal integrity; electrolyte level and clarity; and sedimentation, terminal corrosion, intercell spacers, and rack integrity. Walkdown inspections were performed of areas containing major equipment in the 250 VDC systems to look for evidence of component degradation such as broken control devices, dust, peeling paint, excessive temperature or noise, building leaks or leaks from nearby mechanical equipment and ambient conditions. Ammeters, voltmeters, ground detection and alarms on the DC system equipment were observed and evaluated in relation to the desired state or condition. Problem reports for the past two-year period dealing with grounds on the 250 VDC system were evaluated by the team.
b. Findings
No findings of significance were identified.
.32 Equipment/Environmental Qualification
a. Inspection Scope
The team reviewed qualification test data associated with the environmental testing of the CST header level switches and the HPCI steam line space high temperature switches. The test data was reviewed to confirm that the components were qualified for the worst case postulated accident environments where they are installed. The team also reviewed seismic test data on both instruments to verify that they would perform satisfactorily during and after a seismic event.
In addition to the above, the team reviewed the environmental classification for several other instruments associated with the HPCI system to determine if the components had been properly evaluated for inclusion in the Environmental Qualification (EQ) Program.
The reviewed included the licensees operability evaluation for an EQ issue documented in PER 04-00235-000 involving HPCI instruments that had been classified as essentially mild although they were located in a harsh environment. The team reviewed the PER and the associated operability evaluation to determine if the conclusions were reasonable and acceptable. The team conducted in-plant walkdowns to verify that the observable portions of selected mechanical components were suitable for the environment expected under all conditions, including high energy line breaks (HELBs).
A list of documents reviewed is included in the Attachment to this report.
b. Findings
No findings of significance were identified.
.33 Equipment Protection
a. Inspection Scope
The team walked down the spaces containing 250 VDC equipment and the HPCI and RCIC rooms and reviewed temperature switches qualifications to verify the equipment was adequately protected against external events such as flood, missiles, and HELB.
b. Findings
No findings of significance were identified.
.34 Component Inputs/Outputs
c. Inspection Scope
The team reviewed selected MOV operator requirements calculations and evaluated the capability of the MOVs to perform their design function under degraded voltage and differential pressure conditions. The specific MOVs reviewed are referenced in Section
1R21 .21a. The team reviewed vendor data demonstrating the operating characteristics
for HPCI auxiliary relay 2-73-23A-15 ( i.e., percent pickup and dropout voltage ratings)and compared it to the minimum expected calculated voltages from Calculation ED-Q0999-870066, Rev. 15 to verify that sufficient control voltage was available for satisfactory operation of the relay under worst case design basis voltage conditions. A list of documents reviewed is included in the Attachment to this report.
b. Findings
No findings of significance were identified.
.35 Operating Experience
a. Inspection Scope
The team reviewed the licensees applicability evaluations, extent of condition reviews, and corrective actions for industry and station operating experience issues related to HPCI and RCIC equipment problems, use of non-conservative acceptance criteria in safety related pump surveillance tests, pump-turbine over speed events, and check valve problems to verify that plant specific issues were appropriately identified and addressed. Work orders, procedures, field observations and discussions with engineering staff provided verification that operating experience (OE) related corrective actions were accomplished. The team reviewed a report summarizing the results of the licensees evaluation of safety related logic system testing in response to NRC Generic Letter 96-01. Specifically, the section of the report dealing with HPCI logic system testing was reviewed to verify that logic test deficiencies were properly evaluated. A vendor communication and a Licensee Event Report were reviewed in relation to the 250 VDC system that addressed the potential for spurious operation of protective relays as a result of perturbations on the 250 VDC system which could lead to loss of AC power. The specific industry experience issues and documents reviewed are listed in the Attachment to this report.
b. Findings
No findings of significance were identified.
.4 Identification and Resolution of Problems
a. Inspection Scope
The team reviewed selected system health reports, maintenance records, surveillance test records, and PERs to verify that design and performance problems were identified and entered into the corrective action program. The team assessed the scope of the licensees extent-of-condition reviews and the adequacy of the corrective actions. The team reviewed calibration test records to verify that out of tolerance conditions were properly entered into the corrective action program for evaluation and disposition.
Additionally, the team reviewed a sample of corrective maintenance work orders on the RCIC and HPCI pumps and selected valves. A list of documents reviewed is included in the Attachment to this report.
b. Findings
No findings of significance were identified.
OTHER ACTIVITIES
4OA6 Meetings, Including Exit
The lead inspector presented the inspection results on January 28, 2005, with Mr. M. Skaggs and other members of the licensee staff. Following completion of additional review in the Region II office, a final exit was held by telephone with Mr. T. Abney of your staff on February 7, 2005, to provide an update on changes to the preliminary inspection findings. The licensee acknowledged the findings presented.
Proprietary information is not included in this inspection report.
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee
- T. Abney, Licensing and Industry Affairs Manager
- B. Auckland, Assistant Plant Manager
- J. Davenport, Licensing
- J. Elmerick, Design Engineering
P Olson, Maintenance Manager
- T. Rogers, System Engineer
- M. Skaggs, Site Vice President
NRC (attended exit meeting)
- C. Ogle, RII, Engineering Branch Chief
- B. Monk, Acting Senior Resident Inspector
LIST OF ITEMS
OPENED, CLOSED AND DISCUSSED
None
LIST OF DOCUMENTS
AND EQUIPMENT REVIEWED