IR 05000443/2005002
| ML050700427 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 03/11/2005 |
| From: | Doerflein L NRC/RGN-I/DRS/RSSB |
| To: | Peschel J, Warner M Florida Power & Light Energy Seabrook |
| References | |
| Download: ML050700427 (19) | |
Text
rch 11, 2005
SUBJECT:
SEABROOK NUCLEAR POWER STATION -
NRC INSPECTION REPORT 05000443/2005002
Dear Mr. Warner:
On January 27, 2005, the U. S. Nuclear Regulatory Commission (NRC) completed an engineering team inspection at the Seabrook Nuclear Power Station. The enclosed report documents the results of that inspection, which were discussed with you and members of your staff at the exit meeting on January 27, 2005, and during a subsequent telephone conversation with Mr. M. OKeefe on March 9, 2005.
This 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 inspection consisted of system walkdowns; examination of selected procedures, drawings, modifications, calculations, surveillance tests, and maintenance records; and, interviews with station personnel.
Based on the results of this inspection, there was one NRC-identified finding of very low safety significance (Green), which did not involve a violation of NRC requirements.
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 Public Electronic Reading Room Web site at http://www.nrc.gov/reading-rm/adams.html.
Sincerely,
/RA/
Lawrence T. Doerflein, Chief Safety Systems Branch Division of Reactor Safety Docket No. 50-443 License No. NPF-86 Enclosure: Inspection Report 05000443/2005002
Mr. Mark
SUMMARY OF FINDINGS
IR 05000443/2005002; 01/10/2005 - 01/27/2005; Seabrook Nuclear Power Station; Safety
System Design and Performance Capability This report is for an engineering team inspection, conducted by six Region I inspectors; in addition, the inspection was observed by a representative from the Bulgarian Nuclear Regulatory Agency. One Green finding was identified. The significance of most findings is indicated by their color (Green, White, Yellow, Red) using Inspection manual Chapter 0609,
Significance Determination Process (SDP). Findings for which the SDP does not apply may be Green or be assigned a severity level after NRC management review. The NRCs program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process, Revision 3, dated July 2000.
NRC-Identified and Self-Revealing Findings
Cornerstone: Mitigating Systems
C
- Green.
The team identified a finding regarding the licensees failure to perform an adequate operability determination for a degraded outboard thrust bearing on the turbine-driven emergency feedwater (TDEFW) pump. Specifically, the licensee did not identify how this bearing would have affected the TDEFW pumps ability to provide core cooling during a Station Blackout (SBO). As a result, the TDEFW pump operability and the need for corrective action were based upon a non-conservative technical basis.
The finding is more than minor because it is associated with the Mitigating Systems Cornerstone attribute of Equipment Performance and affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events. Specifically, the licensee did not ensure the reliability of the TDEFW pump to perform its design function during a station blackout. This finding is of very low safety significance since it was a design or qualification deficiency that was confirmed not to result in a loss of function per Generic Letter (GL) 91-18. (Section 1R21.b)
Licensee-Identified Violations
None-ii-
REPORT DETAILS
REACTOR SAFETY
Cornerstones: Initiating Events, Mitigating Systems, and Barrier Integrity
1R21 Safety System Design and Performance Capability (IP 71111.21)
a. Inspection Scope
The inspectors reviewed the design and performance capability of the service water (SW) and auxiliary feedwater (AFW) systems at the Seabrook Nuclear Power Station.
The inspection included a review of the condensate storage tank (CST) and select valves in the SW system. The systems and components were selected because of their risk-significance related to initiating events, mitigating systems, and barrier integrity. In addition, the risk insights and probabilistic risk assessment (PRA) information relative to the selected systems were used to focus inspection activities on components and procedures that would mitigate the effects of the selected events. The inspection procedure used for this effort was IP 71111, Attachment 21.
The AFW system includes the safety-related emergency feedwater (EFW) system and the non-safety related start-up feedwater (SUFW) system. There are two EFW pumps -
a motor driven pump powered from the B emergency electrical bus, and a turbine driven pump which receives its steam from upstream of the main steam isolation valves.
The SUFW pump is powered from a non-emergency electrical bus during plant startups and shutdowns. During power operation, the SUFW pump is powered from the A emergency bus and is used in the event that both EFW pumps are unavailable.
The SW system normally uses the safety-related SW pumps. In the event of a seismic event which collapses the SW suction and/or discharge tunnels, the safety-related mechanical draft cooling tower is available for use. Also included as part of the SW system is a non-safety related portable cooling tower makeup pump system, to fill the tower after about seven days.
The inspectors reviewed licensing and design basis documents for the SW and the AFW systems to determine the functional requirements during normal operation and accident mitigation. The design and licensing documents reviewed for the systems included the Updated Final Safety Analysis Reports (UFSARs), the Technical Specifications (TSs), and the applicable design basis documents for each system and component.
The inspectors reviewed the associated vendor manuals, engineering analyses and calculations, equipment qualification records, instrument set-points and electrical calculations, system modifications, piping and instrument drawings, electrical schematics, instrumentation and control drawings, and logic diagrams. The inspectors conducted this review to verify consistency with the design and licensing basis documents. The inspectors also reviewed completed corrective and preventive maintenance packages, post-maintenance tests, instrument calibration records and surveillance tests to determine the operational readiness, configuration control, and material condition of the systems and components to verify the systems and components were operated and maintained in conformance with the design and licensing bases. In addition, the inspectors reviewed the applicable system health reports to evaluate the current status of the systems and components, as well as any maintenance rule actions being taken as required by 10 CFR 50.62. The inspectors reviewed selected industry operating experience for applicability to Seabrook, and their associated disposition for adequacy.
The inspectors reviewed the system operating procedures, the abnormal and alarm response procedures, and the emergency operating procedures, as applicable. The inspectors reviewed the associated training lesson plans and simulator scenarios to evaluate the consistency between the assumptions made in the design basis and the expected system response. The inspectors conducted detailed walkdowns of the accessible portions of the plant to independently assess the physical condition of the systems and components, and to ensure that availability, reliability, and functional capability had been maintained.
The electrical aspects of the systems were reviewed to assure adequate voltage existed at the components of the selected systems and components. The inspectors reviewed electrical control and logic diagrams for the major components and valves to assure that interlocks and permissive logic were in accordance with system requirements. The inspectors also reviewed 1) the short circuit calculations to assure that circuit breakers were of adequate capacity, and 2) the coordination studies to verify that circuit breakers were set properly to ensure that electrical faults would be isolated locally and that unnecessary tripping of feeder breakers would be avoided. The mechanical inspection of the systems included a walkdown of the accessible portions of the equipment to assess the material condition, and to confirm the existence of adequate controls over nonconforming material and any hazards that could potentially compromise the design function of the systems and components.
The inspectors reviewed how design change work had been implemented and controlled, particularly with regard to system operability status, and to verify system and component availability for the performance of design functions. In addition, field inspections were conducted with particular emphasis upon train separation, physical independence, and other common mode concerns that the design features were intended to address.
The inspectors reviewed training material associated with the operation and maintenance of the selected systems and components, and assessed the Seabrook control room simulator for fidelity with specific plant controls, particularly where field modifications had been effected. The inspectors interviewed applicable personnel responsible for operation and maintenance of the systems, licensing basis controls, and the development and implementation of modifications affecting the systems.
b. Findings
Introduction.
The inspectors identified a Green finding regarding the licensees failure to perform an adequate operability determination for a degraded outboard thrust bearing on the TDEFW pump.
Description.
On May 19, 2004, the outboard thrust bearing on the TDEFW pump approached the alarm set point of 180 degrees Fahrenheit (EF) during an extended (75 minutes) post-maintenance test. The licensee performed an apparent cause evaluation (CR-04-04780) and determined the elevated temperature was most likely caused by the use of an incorrect spacer when the pump was reassembled following an overhaul in March 2001. The spacer was used to set the disc-to-drum clearance, and balance the axial thrust developed by the pump. The apparent cause evaluation also noted that the previous pump runs since the overhaul were not as long and therefore did not reveal the degraded condition. However, this bearing did reach 170EF as the system responded to a plant trip that occurred on October 31, 2001.
On May 20, 2004, the vendor supported the licensees use of 205EF as the revised alarm setpoint for the upper thrust bearing skin/metal temperature. This recommendation was based on, in part, the determination that operation for extended periods on minimum flow recirculation was unlikely to result in other than minor degradation to the outboard thrust bearing. The TDEFW pump was run on May 20, 2004, and allowed to operate until the outboard bearing temperature stabilized at 185EF.
However, the bearing is air-cooled and data collected during the run demonstrated that the outboard bearing temperature increased when the EFW pump house ventilation cycled off toward the end of the test. The ventilation system automatically cycles to maintain ambient temperature approximately 90EF. Based on the test run, the licensee determined that the pump was degraded but operable, with a maximum expected bearing temperature of 185EF. In November 2004, the licensee replaced the TDEFW outboard thrust bearing.
On January 12, 2005, the inspectors identified that the licensee did not conservatively evaluate how the degraded TDEFW outboard thrust bearing would have affected EFW system performance during a station blackout (SBO). One of the design features of the TDEFW pump is to provide core cooling for up to four hours during an SBO. Since both trains of EFW pump house ventilation would not operate during an SBO, ambient temperature could have reached 128EF during this period as indicated by the Seabrook SBO coping analysis. Based on the inspectors questions, the licensee initiated CR-05-01053. As a result, the licensee reevaluated TDEFW pump operability and concluded that the bearing could have reached 223EF with a corresponding oil temperature of 188EF during an SBO. This was approximately 38EF higher then initially determined in May 2004.
On January 27, 2005, the licensee revised their operability determination for past operability and determined that the TDEFW pump was operable based upon discussions with the bearing and oil manufacturer. The licensee determined that the oil would have still retained its lubricating properties and the bearing could have operated at temperatures in excess of 223EF for the four-hour SBO coping period. The inspectors reviewed this evaluation and determined this was a reasonable conclusion.
Analysis.
The performance deficiency was that the licensee failed to adequately evaluate, as required by procedure OE 4.5, Operability Determination, how the degraded bearing on the TDEFW pump could have affected the operability of the pump during an SBO. The procedure requires that an operability determination demonstrate how a system, structure, or component could continue to perform its design safety functions. This procedure was not followed since the operability evaluation technical basis did not support the specific design function of the TDEFW pump to provide core cooling during an SBO.
The finding is greater than minor because it is associated with the Mitigating Systems Cornerstone attribute of Equipment Performance and affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events. Specifically, the licensee did not ensure the reliability of the TDEFW pump to perform its design function during a station blackout. The finding was evaluated using MC 0609, Significance Determination Process, Appendix A, Determining the Significance of Reactor Inspection Findings for At-Power Situations, affecting the Mitigating Systems Cornerstone. The finding was determined to be of very low safety significance (Green) because it was a design or qualification deficiency that was confirmed not to result in a loss of function per Generic Letter (GL) 91-18.
(FIN 05000443/2005-02-01) Failure to Perform an Adequate Operability Determination for the TDEFW Pump
Enforcement.
No violation of regulatory requirements occurred.
4OA2 Identification and Resolution of Problems
a. Inspection Scope
The inspectors reviewed the licensees effectiveness in identifying and resolving problems associated with the SW and AFW systems and the selected components.
The inspectors reviewed CRs, maintenance work orders, engineering change requests, quarterly system health reports, and quality assurance audit reports to assess plant performance and licensee corrective actions. This review was to verify that identified issues were appropriately entered into the corrective action program and resolved in a timely manner. In addition, the inspectors reviewed CRs associated with the licensees audits and self-assessments of these systems.
b. Findings
No findings of significance were identified.
4OA6 Exit Meeting Summary
On January 27, 2005, at the conclusion on the inspection, the inspectors presented the inspection findings to Mr. M. Warner, Site Vice President and members of his staff. A subsequent telephone conversation was held on March 9, 2005 with Mr. M. OKeefe to discuss changes from the information presented at the exit meeting. The inspectors confirmed that the inspection report does contain any proprietary information.
ATTACHMENT:
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee Personnel
- R. Belanger, Principal Design Engineer - Systems
- W. Bladow, Oversight Manager
- R. Campo, Supervisor - Plant Engineering
- L. Carlson, Simulator Instructor
- J. Codi, Work Week Manager
- R. Faix, Supervisor - Design Engineering
- P. Freeman, Engineering Manager
- R. Huntress, Maintenance Technician
- D. Kelly, Emergency Operating Procedure Coordinator
- M. Kiley, Operations Manager
- J. Klempa, Emergency Feedwater System Engineer
- A. Kodal, Component Cooling System Engineer
- J. Kotkowski, Supervisor - Electrical Design
- P. Leary, Shift Manager
- J. Mayer, Condition Based Maintenance - Vibration Monitoring
- R. McCormack, Service Water System Engineer
- S. Morrissey, Assistant Operations Manager
- G. Myers, Nuclear Fuels Engineer
- M. OKeefe, Supervisor - Regulatory Compliance
- R. Parry, Supervisor - Condition Based Maintenance
- V. Petel, Electrical Design Engineer
- E. Spader, Supervisor - Operations Training
- G. St. Pierre, Plant General Manager
- M. Taylor, Supervisor - Work Control
- E. Trump, Fire Protection Engineer
- M. Warner, Site Vice President
- R. White, Design Engineering Manager
- L. Wilson, Seabrook Fire Chief
NRC
- G. Dentel, Senior Resident Inspector, Seabrook
- L. Doerflein, Branch Chief, DRS, Region I
- W. Lanning, Director, Division of Reactor Safety, Region I
LIST OF ITEMS
OPENED & CLOSED Opened and Closed:
- 05000443/2005002-01 FIN Inadequate Operability Determination of the TDEFW Pump Relative to SBO