IR 05000296/2012016
| ML12335A371 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 11/30/2012 |
| From: | Eugene Guthrie Division Reactor Projects II |
| To: | James Shea Tennessee Valley Authority |
| References | |
| IR-12-016 | |
| Download: ML12335A371 (20) | |
Text
UNITED STATES ember 30, 2012
SUBJECT:
BROWNS FERRY NUCLEAR PLANT UNIT 3 - NRC SUPPLEMENTAL INSPECTION REPORT 05000296/2012016
Dear Mr. Shea:
On November 16, 2012, the U. S. Nuclear Regulatory Commission (NRC) completed a supplemental inspection pursuant to Inspection Procedure 95001, Supplemental Inspection for One or Two White Inputs in a Strategic Performance Area, at your Browns Ferry Nuclear Plant, Unit 3. The enclosed inspection report documents the inspection results, which were discussed with Mr. Keith Polson and other members of your staff during the exit meeting on November 16, 2012.
In accordance with the NRC Reactor Oversight Process Action Matrix, this supplemental inspection was performed to follow-up on a white Initiating Events Cornerstone Performance Indicator (PI), Unplanned Scrams per 7,000 Critical Hours for Unit 3, which crossed the Green to White threshold in the second quarter of 2012. TVA informed the NRC of their staffs readiness for this inspection in a letter dated October 12, 2012.
The objectives of the supplemental inspection were to provide assurance that: (1) the root causes and the contributing causes of risk-significant issues were understood; (2) the extent of condition and extent of cause the issues were identified; and (3) the licensees corrective actions were or will be sufficient to address and prevent repetition of the root and contributing causes.
Based on the results of this inspection, we concluded that you have adequately completed a root cause analysis of the issue, and have identified appropriate corrective actions to prevent recurrence of the issue. No findings were identified concerning the root cause evaluation and corrective actions.
The NRC has determined that inspection objectives stated above have been met. Therefore in accordance with IMC 0305, Operating Reactor Assessment Program, the performance issue shall not be considered in the Action Matrix after the end of the second quarter 2012. In accordance with 10 CFR 2.390 of the NRCs 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 the NRCs Agencywide Document Access and Management 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/
Eugene F. Guthrie, Chief Special Project, Browns Ferry Division of Reactor Projects Docket No.: 50-296 License No.: DPR-68
Enclosure:
Inspection Report 05000296/2012016
REGION II==
Docket No.: 50-296 License No.: DPR-68 Report No: 05000296/2012016 Licensee: Tennessee Valley Authority (TVA)
Facility: Browns Ferry Nuclear Plant, Unit 3 Location: Corner of Shaw and Nuclear Plant Roads Athens, AL 35611 Dates: November 13, 2012 through November 16, 2012 Inspector: Michael O. Miller, Senior Project Engineer Approved by: Eugene F. Guthrie, Chief Special Project, Browns Ferry Division of Reactor Projects Enclosure
SUMMARY OF FINDINGS
Inspection Report 05000296/2012016; November 13 - 16, 2012; Browns Ferry Nuclear Plant,
Unit 3; Inspection Procedure 95001, Supplemental Inspection - Inspection Procedure (IP)95001 This inspection was conducted by a senior project engineer. The inspector identified no finding.
The NRCs program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process, Revision 4, dated December 2006.
Cornerstone: Initiating Events
The NRC staff performed this supplemental inspection in accordance with Inspection Procedure 95001, Supplemental Inspection for One or Two White Inputs in a Strategic Performance Area, to assess the licensees evaluations associated with four unplanned and uncomplicated reactor scrams that occurred from September 28, 2011, through May 29, 2012, and caused the Initiating Events Cornerstone Performance Indicator (PI), Unplanned Scrams per 7,000 Critical Hours, to cross the safety significance threshold from Green-to-White in the second quarter of 2012.
During this supplemental inspection, the inspector determined that the licensee performed a comprehensive evaluation of each of the four reactor scrams individually and then performed a collective evaluation of the four reactor scrams (three were automatic scrams and one was a manual scram) to determine if there were underlying causes that were common to the four scrams. The licensee concluded that the root cause for the automatic scrams was a less than adequate review of vendor supplied design change products. The licensee concluded that the manual scram did not have a common root cause with the other three scrams.
The Unplanned Scrams Per 7000 Critical Hours PI will be considered in plant performance assessment until the PI returns to the green performance band in accordance with the guidance in IMC 0305, Operating Reactor Assessment Program. The implementation and effectiveness of the licensees corrective actions will be reviewed during future routine NRC inspections.
Findings No findings were identified.
REPORT DETAILS
OTHER ACTIVITIES
Cornerstones: Initiating Events, Mitigating Systems, Barrier Integrity, Emergency Preparedness
4OA3 Event Follow-up
.1 (Closed) Licensee Event Report (LER) 05000296/2012-004-00: Manual Reactor Scram
During Start-up Due to Multiple Control Rod Insertion (Unit 3)
On May 24, 2012, at approximately 0638 Central Daylight Time, the Browns Ferry Nuclear Plant (BFN) Unit 3 operators manually scrammed the reactor during a unit startup. An operator inadvertently took intermediate range monitor (IRM) 3H range switch from Range 6 to Range 5. This caused IRM 3H to go upscale and insert a half scram signal on the 3B reactor protection system (RPS) trip channel. The operator then took IRM 3H range switch to Range 7 to clear the upscale half scram signal. The operating crew then attempted to reset the half scram. When an operator took the scram reset switch to the Group 2/3 reset position, IRM 3A generated an electrical spike on RPS 3A trip channel. This caused Groups 1 and 4 control rods to scram. Operations personnel saw unexpected control rod motion and scrammed the reactor manually as required by BFN Procedure, 3-AOI-l00-1, Reactor Scram. The NRC issued inspection report 05000259/2012003 on August 14 which documented the initial follow-up inspection of this event by the resident inspectors in Section 4OA3.
The inspector reviewed Licensee Event Report 50-296/2012-004-00, Manual Reactor Scram During Startup Due to Multiple Control Rod Insertion, that TVA issued on July 23, 2012 and its associated problem evaluation report (PER) 558437, including the root cause analysis (RCA) and corrective actions. The inspector interviewed the reactivity manager and the off-going and on-coming licensed operators that were conducting shift turnover when this event occurred. The inspector found that the shift supervisor chose to conduct shift turnover while an active plant evolution of reactor plant heat-up was in progress and that this event happened during that turnover. The inspector concluded that the Unit Supervisor complied with Procedure OPDP-1, Conduct of Operations, revision 0024, when he determined that pre-job briefs were necessary and that he conducted pre-job briefs with appropriate on-coming watch standers and supervisors.
The inspector reviewed the event with management personnel in operations, maintenance, engineering, and licensing to gain an understanding of the conditions that lead up to the event and to assess licensee actions taken surrounding this event. The licensees root cause concluded that a signal spike was induced in IRM 3A because IRM 3A had a high impedance from the main control room common ground to station ground and this exposed IRM 3A to noise feedback when the operator took the scram reset switch to the Group 2/3 position. This caused a half scram on RPS 3A. After the plant shutdown was completed, craftsmen troubleshot the instrumentation and found the spiking on IRM 3A was repeatable. The licensee added ferrite beads to source range monitor (SRM,) IRM, and the scram reset switch wires to make them less susceptible to electrical spikes. The craftsmen repeated the test and found minimal spiking on IRM 3A.
The craftsmen found IRM 3A shield wire loose and then tightened and cleaned the connector. The retest found no response (spiking) on any IRM or SRM. The inspectors concluded that the licensees corrective actions in response to this event were appropriate. The corrective actions included retraining the operator on the proper use of self-checking and peer-checking, repairing IRM 3A, adding additional hardware (ferrite beads), and examining Units 1 and 2 IRMs and SRMs for similar susceptibility.
The licensee conducted an extent of condition investigation. The initial population for the extent of condition investigation included corrective actions for all safety systems and components from May 2007 through May 2012. The licensee created work orders to inspect and make repairs as required for the high voltage connectors associated with the IRMs on all three units during the next scheduled calibration surveillance which manipulates the high voltage cable. During the extent of condition investigation, the licensee concluded that this condition extended to all IRMs and SRMs in Unit 3 and spikes were not a problem with other plant systems or components important to safety, including IRMs and SRMs in Units 1 and 2.
The inspector also verified:
- (1) the licensee made timely notifications as required by 10 CFR 50.72(b)(2)(iv)(B) and (b)(3)(iv)(A);
- (2) the licensee staff properly implemented the appropriate plant procedures, and
- (3) the available plant equipment performed as required during the event. The inspector reviewed the root cause analysis and corrective actions, PER 558437.
.2 Findings
No findings were identified.
4OA4 Supplemental Inspection
.01 Inspection Scope
The NRC staff performed this supplemental inspection in accordance with inspection procedure (IP) 95001 to assess the licensees evaluation of a White performance indicator (PI,) which affected the initiating events cornerstone in the reactor safety strategic performance area on Unit 3. The inspection objectives were to:
- provide assurance that the root and contributing causes of risk-significant issues were understood;
- provide assurance that the extent of condition and extent of cause of risk-significant performance issues were identified;
- provide assurance that the licensees corrective actions for risk-significant issues were or will be sufficient to address the root and contributing causes and to preclude repetition.
The licensee entered the Regulatory Response Column of the NRCs Action Matrix for Unit 3 in the second quarter of 2012 as a result of a White violation for failure to implement appropriate Safe Shutdown Instructions (NRC Inspection Reports 05000259, 260,296/2012007 and 05000259, 260,296/20120013)..
This PI was associated with unplanned scrams per 7,000 critical hours and was characterized as having White safety significance based on crossing the Green-to-White threshold of more than three scrams in four quarters. There were three automatic and one manual scram during four quarters. The NRC issued inspection reports which documented the initial event follow-up inspection of the individual scrams that contributed to crossing the Green-to-White threshold of more than three scrams in four quarters. The following is a list of those four inspection reports.
- Inspection Report (IR) 05000296/2011004 Section 4OA3.10, Unit 3 Automatic Reactor Scram occurring on September 28, 2011
- IR 05000296/2011004 Section 4OA3.1 Unit 3 Automatic Reactor Scram Following Refueling on May 22, 2012
- IR 05000296/2011004 Section 4OA3.2 Unit 3 Manual Reactor Scram Following Refueling on May 24, 2012
- IR 05000296/2011004 Section 4OA3.3 Unit 3 Automatic Reactor Scram Following Refueling on May 29, 2012 The licensee staff informed the NRC staff on October 12 that they were ready for the supplemental inspection. In preparation for the inspection, the licensee performed a collective root cause analysis (RCA) PER, RCA PER 562343, Revision 2, of the four reactor scrams to identify weaknesses that existed in various organizations, which allowed for a risk-significant PI, and to determine the organizational attributes that resulted in the White PI. The licensee also compiled a safety culture self-assessment in RCA PER 562343.
The inspector reviewed the licensees RCA in addition to other evaluations conducted in support and as a result of the RCA. The inspector reviewed corrective actions that were taken or planned to address the identified causes. The inspector also held discussions with licensee personnel to ensure that the root and contributing causes and the contribution of safety culture components were understood and corrective actions taken or planned were appropriate to address the causes and preclude repetition.
.02 Evaluations of the Inspection Requirements
02.01 Problem Identification a. IP 95001 requires that the inspection staff determine that the licensees evaluation of the issue documents who identified the issue (i.e., licensee-identified, self-revealing, or NRC-identified) and the conditions under which the issue was identified.
The inspector determined that the licensees RCA implicitly stated that the four scrams were self-revealing and that the RCA explicitly identified that the conditions under which the scrams occurred were identified, well known, and understood.
b. IP 95001 requires that the inspection staff determine that the licensees evaluation of the issue documents how long the issue existed and prior opportunities for identification.
The inspector concluded that the licensees RCAs for the individual scrams were generally effective in documenting how long issues existed and prior opportunities for identification.
c. IP 95001 requires that the inspection staff determine that the licensees evaluation documents the plant specific risk consequences, as applicable, and compliance concerns associated with the issue.
The NRC determined this issue was a White PI, and the licensees RCA also documented that the PI associated with this issue had White safety significance. In addition, RCA PER 562343 documented the consequences of the issue, which included the following:
- Unplanned unavailability of Unit 3
- Unscheduled emergent maintenance
- A White PI The inspectors concluded that the licensees RCAs were generally effective in documenting the plant specific risk consequences, as applicable, and compliance concerns associated with the issue.
d. Findings
No findings were identified.
02.02 Root Cause, Extent of Condition, and Extent of Cause Evaluation a. IP 95001 requires that the inspection staff determine that the licensee evaluated the issue using a systematic methodology to identify the root and contributing causes The licensee used the following systematic methods to complete RCA PER 562343:
- data gathering through interviews and document review;
- barrier analysis;
- event and causal factors chart;
- organizational and programmatic deficiency evaluation;
- common cause analysis; and
- safety culture evaluations for SCRAM issues.
The inspectors determined that the licensee evaluated the issue using a systematic methodology to identify root and contributing causes.
b. IP 95001 requires that the inspection staff determine that the licensees RCA was conducted to a level of detail commensurate with the significance of the issue The licensees RCA included a barrier analysis of the event and an event and causal factor chart as discussed in the previous section. The licensee concluded that the less than adequate vendor product review issue was not limited to the three automatic scrams and that the issue applied to other engineering work products on safety-related equipment. The licensee conducted a review of recently installed engineering work products and found no deficiencies in the installation of these products. The licensees RCA documented the root cause of the issue to be the stations processes allowed for less than adequate review of vendor supplied design change products, which resulted in an automatic scram in September 2011 and two automatic scrams during startup following the refueling outage in May 2012. The licensee determined that the contributing causes included:
- (1) inadequate use of the corrective action program,
- (2) knowledge deficiencies in development of post maintenance test instructions, and
- (3) inadequate procedure use and adherence. Based on the extensive work performed for this root cause evaluation, the inspectors concluded that the root cause evaluation was conducted to a level of detail commensurate with the significance of the problem.
c. IP 95001 requires that the inspection staff determine that the licensees RCA included a consideration of prior occurrences of the issue and knowledge of Operating Experience (OE.)
The licensees RCA included an evaluation of internal (TVA wide) and external OE. The licensee considered prior occurrences and OE. As a result of this review, the licensee determined the May 24, 2012 scram was not OE preventable. The licensee also determined that the relevant industry OE provided lessons learned for the other three scrams in the areas of:
- (1) vendor oversight;
- (2) additional post modification testing; (3)enhanced risk reviews; and
- (4) application of OE lessons learned. The licensee made three entries into their corrective program (PERs 440359, 547431, and 57183) for three scram events being OE preventable.
In addition, the licensee performed a common cause analysis. A list of common causes was developed using the systematic methods to complete RCA PER 562343 as listed above. Based on the licensees detailed evaluation and conclusions, the inspectors concluded that the licensees RCA included a consideration of prior occurrences of the problem and knowledge of prior OE.
d. IP 95001 requires that the inspection staff determine that the licensees RCA addresses the extent of condition and extent of cause of the issues.
The licensees evaluation of extent of condition review was an analysis of the four Unit 3 scram events to examine the licensees response to the declining Unplanned Scrams per 7000 Critical Hours PI as each scram occurred. The event and causal factor chart, (written to address the declining PI) showed that procedural guidance to make a corrective action program entry when a PI falls below the 50% margin to the Green-to-White threshold was not followed in all cases. The licensee created PER 601479 to enter this issue in the licensees corrective action process. The <50% Green band requirement was revised to require a corrective action program entry and an action plan earlier, to when a PI drops below the 75% margin to the Green-to-White threshold.
The licensees evaluation also considered the extent of cause associated with the less than adequate rigor in the review of vendor supplied design change products. The licensee staff determined that the issue of less than adequate rigor in the review of vendor supplied design change products had the potential to exist in other station departments and in multiple areas including use of OE, development of post maintenance test instructions, vendor oversight, timely and effective corrective actions, and procedure use and adherence.
The inspectors concluded that the licensees RCA addressed the extent of condition and the extent of cause of the issue.
e. IP 95001 requires that the inspection staff determine that the licensees root cause, extent of condition, and extent of cause evaluations appropriately considered the safety culture components as described in IMC 0305.
Because the licensee recognized safety culture aspects were associated with this issue, the licensee conducted a review of the areas of safety culture (human performance, problem identification and resolution, and safety conscious work environment)components and aspects. The licensee documented the results of this review in narrative format and then assigned a cause code, and basis for that assignment, to each aspect that applied to this issue. The inspector concluded that the licensees RCA was generally effective in considering the safety culture components in root causes, extent of condition, and extent of cause. The inspector noted that the licensees evaluation process considers the applicability of each safety culture aspect and then addresses those that are determined to be applicable.
f. Findings
No findings were identified.
02.03 Corrective Actions a. IP 95001 requires that the inspection staff determines that
- (1) the licensee specified appropriate corrective actions for each root and/or contributing cause, or
- (2) an evaluation that states no actions are necessary is adequate.
No immediate actions were identified or required because the licensee took immediate and interim corrective actions to restore the functionality of the problem components after each scram. These actions were documented in each of the RCAs for the individual scrams. The corrective actions for the root and contributing causes listed in RCA PER 562343 were appropriate. To address the root cause (less than adequate review of vendor supplied design change products) the licensee:
- (1) revised procedures to provide a clear standard for performance of review of vendor supplied design change products (including a change management plan),
- (2) issued a requirement to document OE reviewed and actions taken to mitigate trip risk, and
- (3) add a procedural requirement that technical knowledge workers apply human performance tools (technical conscience principles, focus technical task risk factors, mitigation strategies, and decision making) including a requirement to develop a change management plan that includes training and implementation of the change management plan. To address the three contributing causes for the four unplanned scrams in four quarters, the licensee developed a list of ten corrective actions (with supporting sub-activities). The inspector determined that the proposed corrective actions were appropriate and addressed each root and contributing cause.
b. IP 95001 requires that the inspection staff determine that the licensee prioritized corrective actions with consideration of risk significance and regulatory compliance.
The licensees corrective actions to address the root and contributing causes were prioritized in accordance with TVA procedure NPG-SPP-03.1.6, Root Cause
Analysis.
The corrective actions were prioritized with consideration for risk significance and regulatory compliance and the basis was documented in the RCA report. The licensees plan to verify vendor information was implemented according to the risk significance of the equipment. The inspectors reviewed the licensees plans for accomplishing this activity and noted that the risk significance of the equipment was being appropriately considered. Based upon the guidance in NPG-SPP-03.1.6 and the prioritization of the corrective actions in accordance with this procedure, the inspectors determined that the corrective actions were prioritized with consideration of the risk significance and regulatory compliance.
c. IP 950011 requires that the inspection staff determine that the licensee established a schedule for implementing and completing the corrective actions.
The inspector concluded that the licensees RCAs were generally effective in establishing a schedule for implementing and completing corrective actions.
d. IP 95001 requires that the inspection staff determine that the licensee developed quantitative and/or qualitative measures of success for determining the effectiveness of the corrective actions to preclude repetition.
As documented in ACE PER 562343, the licensee established measures for determining the effectiveness of the corrective actions. These measures included qualitative and quantitative assessments. These measures included the following:
The licensee will perform a snapshot assessment six months following implementation of revised Procedure HPG-SPP-18.2.2, Human Performance. An additional assessment is to be performed around one year following implementation of NPG-SPP-18.2.2. The goal is no deficiencies identified following design change notice independent review.
The qualitative assessment is to conduct a snapshot assessment of technical review of vendor supplied products, including an external subject matter expert. The quantitative portion of the effectiveness review for the White PI will be each unit achieving:
- Less than or equal to 1 reactor scram per 7,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of critical operation
- Less than or equal to 3 unplanned down power events >25 percent per 7,000 critical hours
- No site clock resets for technical rigor identified in plant trips and a steadily declining overall site clock resets for technical rigor identified for six months The licensee staff entered these corrective action items into their corrective action program to ensure that these effectiveness reviews and enhanced monitoring were performed. The inspector determined that quantitative and qualitative measures of success had been developed for determining the effectiveness of the corrective actions to preclude repetition.
e. IP 95001 requires that the inspection staff determine that the licensees planned or taken corrective actions adequately address a Notice of Violation (NOV) that was the basis for the supplemental inspection, if applicable.
The inspector concluded that a NOV was not part of the basis for this supplemental inspection.
f. Findings
No findings were identified.
4OA6 Meetings, Including Exit
.1 Exit Meeting
On November 16, 2012, the inspector presented the inspection results to Mr. Keith Polson, Site Vice President, and other members of his staff, who acknowledge there were no findings. The inspector asked the licensee if any of the material examined during the inspection should be considered proprietary. The licensee did not identify any proprietary information that had not been returned to the licensee.
ATTACHMENT:
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee personnel
- R. Beck, Instrument and Controls System Supervisor
- C. Besehern, Browns Ferry Quality Assurance Manager
- J. Browder, Performance Improvement
- E. Cobey, Licensing
- E. Cole, Nuclear Unit Operator
- R. Collins, Quality Assurance
- J. W. Davenport, Site Licensing
- G. J. Doyle, Director 95003
- J. Emens, Site Licensing Manager
- B. Grant, Browns Ferry Maintenance Manager
- L. Hughes, Operations Manager
- S. W. Hunnewell, Browns Ferry Director of Engineering
- R. Kerving, Corrective Program Manager
- R. King, Design Engineering Manager
- D. Johnston, Assistant Engineering Director
- K. Jones, 95001 Team and General Manager Nuclear Systems and Programs
- J. Knight, Nuclear Unit Operator
- T. McCaney, Assistant Unit Operator and Certified Root Cause Analyst
- J. Miller, 95001 Team
- G. Moore, Engineering Support Supervisor
- W. Miller, Shift Technical Advisor
- B. Lee Millsaps, Nuclear Unit Operator
- R. Myatt, 95001 Team, Equipment Reliability
- S. Neudigate, 95001 Team, Operations Instructor
- M. Oliver, Site Licensing
- M. Nelson, Nuclear Unit Operator
- M. Palmer, Corporate Management
- M. Payne, Heat Exchanger and Thermal Performance Manager
- R. Pochron, 95001 Team, Maintenance
- K. Polson, Site Vice President
- A. Reagan, Site Communications
- K. Selph, Communications
- T. Scott, Performance Improvement Manager
- S. Spears, Maintenance
- P. B. Summers, Director Safety & Licensing
- N. Thomas, Performance Analysis Program Manager
- R. Welchans, Nuclear Unit Operator
- B. Williamson, Reactor Engineer
- C. Wilson, System Engineer
- J. Yarbrough, Assistant Engineering Director
NRC personnel
- D. Dumbacher, Senior Resident Inspector, Browns Ferry Nuclear Plant
- L. Pressley, Resident Inspector, Browns Ferry Nuclear Plant
- E. Guthrie, Chief, Special Projects, Browns Ferry Nuclear Plant
LIST OF ITEMS
OPENED, CLOSED AND DISCUSSED
Opened
None
Opened and Closed
None
Closed
LER
- 05000296/2012-004-00 LER Manual Reactor Scram During Startup Due to Multiple Control Rod Insertion (Section 4OA3.1)