IR 05000456/2010009
Download: ML103330180
Text
November 26, 2010
EA-09-259 Mr. Michael Senior Vice President, Exelon Generation Company, LLC President and Chief Nuclear Officer (CNO), Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT: BRAIDWOOD STATION, UNIT 1, SUPPLEMENTAL INSPECTION REPORT 05000456/2010009
Dear Mr. Pacilio:
On November 1, 2010, the U. S. Nuclear Regulatory Commission (NRC) completed an inspection at your Braidwood Station, Unit 1. The enclosed report documents the inspection results, which were discussed during a Regulatory Performance Meeting on November 1, 2010, with Mr. A. Shahkarami, and other members of your staff. As required by the NRC Reactor Oversight Process (ROP) Action Matrix, this supplemental inspection was performed in accordance with Inspection Procedure 95001, "Inspection for One or Two White Inputs in a Strategic Performance Area." The purpose of the inspection was to examine the causes for and actions taken related to a finding having low-to-moderate safety significance (i.e., White) at the Braidwood Station. The finding involved a June 24, 2009, failure of Unit 1 Containment Sump Suction Isolation Valve 1SI8811B to open during surveillance testing. The inspectors determined that measures were not established to ensure the appropriate selection and suitability of application of equipment essential to the safety-related function of the 1SI8811B valve. Specifically, the design of the 1SI8811B motor-operated valve actuator and associated conduit were not suitable to the application, because the design allowed water to enter and collect inside the actuator. This resulted in the failure of the 1SI8811B valve to open during surveillance testing on June 24, 2009, due to corrosion of the torque switch. This issue was documented in NRC Inspection Report 05000456/2009007. The NRC staff was informed on July 22, 2010, of your staff's readiness for this inspection. This supplemental inspection was conducted to provide assurance that the root causes and contributing causes of the event resulting in the White finding were understood, the extent of condition and extent of cause were identified, and that the corrective actions were sufficient to address the root causes and contributing causes and to prevent recurrence. The inspection examined activities conducted under your license as they relate to safety and compliance with the Commission's rules and regulations and with the conditions of your license. The inspector reviewed selected procedures and records and interviewed personnel. The inspector determined that your root cause evaluation was conducted to a level of detail commensurate with the significance of the problem and reached reasonable conclusions as to the root and contributing causes of the event. The inspector also concluded that you identified the extent of condition and extent of cause of the issue, that you identified appropriate corrective actions for each root and contributing cause, and that you appropriately prioritized these actions. 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 System (PARS) component of NRC's Agencywide Documents Access and Management 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 by Kenneth G. O'Brien for/ Gary L. Shear, Acting Director Division of Reactor Projects
Docket No. 50-456 License No. NPF-72
Enclosure:
Inspection Report 05000456/2010009
w/Attachment:
Supplemental Information cc w/encl: Distribution via ListServ Enclosure U. S. NUCLEAR REGULATORY COMMISSION REGION III Docket No: 50-456 License No: NPF-72
Report No: 05000456/2010009 Licensee: Exelon Generation Company, LLC Facility: Braidwood Station, Unit 1 Location: Braceville, Illinois Dates: October 18, 2010, through November 1, 2010 Inspector: C. Phillips, Senior Resident Inspector, Dresden Nuclear Power Station Approved by: E. Duncan, Chief Branch 3 Division of Reactor Projects Enclosure
SUMMARY OF FINDINGS
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REPORT DETAILS
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OTHER ACTIVITIES
...................................................................................................... 2 4OA4Supplemental Inspection ( Inspection Procedure 95001) .................................... 24OA5Other .................................................................................................................. 124OA6Meetings, Including Exit ..................................................................................... 12
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
..................................................................................................... 1
LIST OF ITEMS
OPENED, CLOSED AND DISCUSSED ......................................................... 1
LIST OF DOCUMENTS REVIEWED
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LIST OF ACRONYMS
- US [[]]
ED .................................................................................................... 3
Enclosure
- OF [[]]
- FINDIN [[]]
GS IR 05000456/2010009; October 18, 2010 - November 1, 2010; Braidwood Station, Unit 1 Supplemental Inspection - Inspection Procedure 95001. This supplemental inspection was performed by the Dresden Nuclear Power Station Senior Resident Inspector. The significance of most findings is indicated by their color (Green, White,
Yellow, Red) using Inspection Manual Chapter (IMC) 0609, "Significance Determination
Process" (SDP). Findings for which the SDP does not apply may be Green or be assigned a
severity level after
NRC's program for overseeing the safe
operation of commercial nuclear power reactors is described in
NRC-Identified and Self-Revealed Findings Cornerstone: Mitigating Systems This supplemental inspection was performed in accordance with Inspection Procedure 95001, "Inspection for One or Two White Inputs in a Strategic Performance Area," to assess the licensee's root cause evaluation, extent of condition and extent of cause determination, and corrective actions for the failure
on June 24, 2009, of Unit 1 Containment Sump Suction Isolation Valve 1SI8811B
to fully open during surveillance testing. This finding was previously characterized
as having low-to-moderate safety significance (i.e., White) in an
- NRC letter dated February 25, 2010, which finalized the preliminary assessment of the finding documented in
NRC Inspection Report 05000456/2009007. During this inspection, the inspector determined that the licensee's root cause evaluation was conducted to a level of detail commensurate with the significance of the problem
and reached reasonable conclusions as to the root and contributing causes of the event.
The inspector also concluded that the licensee identified appropriate corrective actions for each root and contributing cause and that these actions were appropriately prioritized. Given the licensee's acceptable performance in addressing the failure of Unit 1 Containment Sump Suction Isolation Valve 1SI8811B to open during surveillance
testing, the White finding associated with this issue will be closed at the end of 2010 in accordance with the guidance in Inspection Manual Chapter 0305, "Operating Reactor Assessment Program." B. Licensee-Identified Violations No findings of significance were identified.
Enclosure
- REPORT [[]]
- OTHER [[]]
- 4OA 4 Supplemental Inspection (Inspection Procedure 95001) .01 Inspection Scope This inspection was conducted in accordance with Inspection Procedure (
IP) 95001, "Inspection for One or Two White Inputs in a Strategic Performance Area," to assess the
licensee's evaluation of one inspection finding of low-to-moderate safety significance
(i.e., White) in the Mitigating Systems cornerstone. The inspection objectives were to: Provide assurance that the root causes and contributing causes of risk-significant performance issues were understood; Provide assurance that the extent of condition and extent of cause of risk-significant issues were identified; and Provide assurance that the licensee's corrective actions to address risk-significant performance issues were or will be sufficient to address the root causes and contributing causes, and to prevent recurrence. By letter dated February 25, 2010, the NRC communicated to Braidwood Station the final significance determination for a finding having low-to-moderate safety
significance (i.e., White), with one associated violation of NRC requirements. The
specific finding was that the design of the Unit 1 Containment Sump Suction Isolation
Valve
MOV) actuator and associated conduit were not suitable to the application, because the design allowed water to enter the conduit and collect inside the actuator. This resulted in the failure of valve 1SI8811B to stroke full
open during surveillance testing on June 24, 2009. The details of the performance issues and the preliminary results of the
NRC Inspection Report 05000456/2009007. Braidwood Station, Unit 1, entered the Regulatory Response column of the NRC's Action Matrix in the fourth quarter of 2009 based on the White inspection finding. On
July 22, 2010, the licensee notified the
- NRC that applicable corrective actions for the finding had been completed or initiated, and that the station was prepared for the
NRC
to conduct this supplemental inspection to review the licensee's evaluation of the causes
and the actions taken to address the White finding. The inspector reviewed root cause evaluation (RCE) 98732, "1SI8811B Valve Failure," Revision 0, dated November 23, 2009, in addition to other evaluations conducted in
support and as a result of the root cause evaluation. 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 prevent
recurrence.
Enclosure .02 Evaluation of the Inspection Requirements 02.01 Problem Identification a. Determine that the evaluation documented who identified the issue (i.e., license-identified, self-revealed, or
- NRC [[-identified) and under what conditions the issue was identified. The inspector determined that the licensee's root cause evaluation adequately described who identified the issue and under what conditions the issue was identified. During scheduled surveillance testing on June 24, 2009, operators attempted to open Containment Sump Suction Isolation Valve 1]]
SI8811B. The control board displayed dual indication and never indicated full open. At the valve, observers identified an approximate 30-40 percent open condition. The licensee initiated Issue Report
(IR) 934782,"1SI8811B Failed to Stroke Full Open During Surveillance," to document the
failure. Upon investigation, the licensee identified water in the actuator limit switch (LS)
compartment, and that the actuator torque switch and the internal
LS compartment through an electrical conduit penetration. The licensee replaced the corroded torque switch and LS
components, and the LS compartment and wiring were cleaned and dried. On June 26,
2009, the valve was satisfactorily tested and returned to service. About 4 months later, on October 30, 2009, a system engineer performing a general walkdown of the Unit 1 curved wall area (CWA) identified water dripping from a leak in the removable roof plug and falling in the area of the 1SI8811B valve. Further inspection
identified water in the stem nut area of the valve forming a puddle about 2 to 3 inches
deep on top of the actuator. During the several hours immediately prior to this
discovery, heavy rains had been experienced at Braidwood Station. The licensee performed a borescope inspection in the actuator
SI8811B valve and found water. The licensee performed an as-found stroke test and the valve functioned properly. Troubleshooting identified a loose compression fitting in
the electrical conduit connection on the actuator LS compartment. The licensee
conducted further testing and concluded the loose conduit connection was the water
entry point. The licensee repaired the conduit connector, and the compartment and components were cleaned and dried. Subsequently, the valve was re-tested and returned to service. As a result of the second event, the licensee initiated IR 987342,
"Water in Actuator Limit Switch Compartment Valve 1SI8811B." On November 23, 2009, the licensee completed its initial root cause evaluation to investigate the organizational and programmatic issues that led to this event. b. Determine that the evaluation documented how long the issue existed and prior opportunities for identification. The inspector determined that the licensee's root cause evaluation provided a detailed chronology of the event, including the issues and actions leading up to and directly
influencing the event.
Enclosure The root cause evaluation detailed the findings from both the June and October 2009 events. The exact date and time of the 1SI8811B valve failure could not be determined,
since the licensee stroked the valve on an 18-month frequency. The licensee last performed preventative maintenance on the 1SI8811B valve on May 17, 2006, when the valve actuator was overhauled and diagnostic testing was performed. The associated
work package did not document the presence of water in the valve. The licensee
concluded that the water entered the 1SI8811B valve sometime after May 17, 2006.
The last successful valve stroke was performed on September 20, 2007. In addition, the root cause evaluation discussed two other Braidwood motor-operated valves (MOVs) with similar failures. On August 12, 1990, Unit 1 Containment Sump Suction Isolation Valve 1SI8809A failed to stroke open after it was closed during
surveillance testing. The license dispatched a non-licensed operator to the valve, and
manually opened the valve. Later, upon opening the LS compartment of the valve, the licensee discovered that water intrusion had occurred causing corrosion of the torque switch. The corrosion caused binding and prevented the torque switch from freely moving. A potential cause of the water intrusion was determined to be draining
operations of lines above the valve resulting in the inadvertent introduction of water on
the valve. The licensee considered this an isolated event, and took no further action. On May 14, 2002, while performing a surveillance test, the licensee successfully closed
CS001A, which failed to re-open with dual position indication. During troubleshooting, the licensee discovered about one quart of water in the LS
compartment. The licensee determined that the LS compartment cover was mounted
tightly to the actuator, and that the gasket was in good condition. The licensee
determined that water entered the LS compartment through the flexible (flex) conduit,
which did not fully extend under the sealing ring of the liquid-tight fitting. The licensee also discovered that the flex fitting at the MOV was very loose. The combination of the exposed inner metal jacket above the sealing ring and the loose flex fitting appeared to
be the likely intrusion path into the LS enclosure. The likely source of water was from
valve
CS001A that inadvertently had been left open during a local leak
rate test on January 18, 2002. These two occurrences were potential missed opportunities to discover the impact of water intrusion on valves in the
SI8811B valve stroke failures.
The licensee's root cause report also stated that based on previous
CWA leaks,
roof leaks have been a known condition since 1998. The inspector concluded that this
was also a missed opportunity to prevent the
- 1SI [[8811B valve stroke failures. c. Determine that the evaluation documented the plant-specific risk consequences, as applicable, and compliance concerns associated with the issue. The inspector determined that the root cause evaluation adequately documented the plant-specific risk consequences associated with the event. The licensee evaluated the safety significance of this issue using the]]
- NRC [['s Significance Determination Process (SDP) and Braidwood Probabilistic Risk Assessment (PRA) Application Notebook]]
SDP-003. The licensee estimated the incremental risk posed by the failure of 1SI8811B to fully open for the presumed length of time the valve was
not fully capable of opening. Because the exact failure date was unknown, the licensee
Enclosure applied the T/2 rules to calculate the
- PRA risk significance. In this case, 322 days was the time period assumed. The licensee submitted additional information concerning the
BW100007 dated January 14, 2010, following a Regulatory Conference that was held on January 6, 2010. The information submitted did not
change the initial position or conclusion presented during the Regulatory Conference or
the root cause report. The failure of the
- SI 8804B valve was required to open to establish flow from the containment sump to the high and intermediate head emergency core cooling system (ECCS) pumps during the cold leg recirculation phase of
CV8804A, the redundant valve for supplying water
from the containment sump to the high and intermediate head
- EC [[]]
CS pumps, was not
affected by the failure of
ECCS. The licensee evaluated this event to determine past operability and to determine the ability of the valve to pass design flow at the as-found opening travel position for the
valve. Based on the failure mode, the valve would have been capable of opening to the bypass
ECCS recirculation flow at this partial opening position. One minor finding concerning the licensee's response to the violation associated with this event is discussed in Section 2.03.e of this report. d. Findings No findings of significance were identified. 02.02 Root Cause, Extent of Condition, and Extent of Cause Evaluation a. Determine that the problem was evaluated using a systematic methodology to identify the root and contributing causes. The licensee used several systematic processes to identify the root causes and the contributing causes for the event. Event and Causal Factor charting was used to provide a graphical display of the events leading up to the 1SI8811B valve stroke failure on June 24, 2009, and the identification of additional water in the valve on
October 30, 2009. The licensee used the Kepner-Tregoe (K-T) Problem Analysis process to identify possible causes for the failure of the 1SI8811B valve to stroke open. The process
identified that water from various sources, including non-watertight floor plugs, removable roof concrete slabs, and maintenance activities within the CWA, had leaked onto the actuator, which may not have been watertight. The K-T analysis for this event
demonstrated that leaks from multiple sources could have caused all of the MOV
failures.
Enclosure The licensee used Barrier Analysis and Causal Factor charting to identify failures or challenged barriers. The licensee identified weaknesses in the corrective action process
that could have previously identified equipment limitations and corrective actions that would have prevented the June 24, 2009, valve failure. Additionally, weaknesses in the corrective action, work control, and Maintenance Rule processes were identified that
could have prevented or mitigated the event by prompt identification and repair of the improperly installed and leaking removable concrete roof slabs. The licensee used Taproot Analysis to analyze and evaluate the identified causal factors and develop trend codes. Following the October 30, 2009 event, Braidwood Station initiated a root cause evaluation to investigate the programmatic and organizational issues that led to the
failure of the
- 1SI 8811B valve. The licensee identified the root cause to be that station personnel did not fully understand that the
- CWA design configuration did not incorporate watertight electrical components to prevent water intrusion. As a result, station personnel lacked sensitivity to the effects of water spills, sprays, or leaks in the
- CWA. [[The licensee identified the following contributing causes in the root cause evaluation: 1. Station personnel did not identify and take action to correct the missing multi-ply insulated roof membrane as identified in design drawings to cover and seal the concrete removable slabs in the]]
CWA roof.
2. The sealtight conduit connector for 1SI8811B was not properly installed. The fitting gasket was missing and was replaced during troubleshooting and repair of
the actuator. While electrical conduits were not required to be watertight, proper
installation of the conduit connector may have precluded water intrusion into the actuator compartment. In addition to the root and contributing causes, the licensee identified causal factors in
the root cause evaluation, including: 1. Long-standing material condition issues were left for a significant period of time without adequate resolution.
2. Station personnel did not consistently initiate
CWA roof leaks. As a result, a
degrading or changing condition potentially went unreported or existing work
orders (WOs) were not reprioritized as might have been required. b. Determine that the root cause evaluation was conducted to a level of detail commensurate with the significance of the problem. The inspector determined that the licensee conducted the final root cause evaluation at an appropriate level. The licensee performed a thorough examination of the equipment, design, and organizational problems that led to the event.
Enclosure The final root cause evaluation discussed weaknesses in the original Equipment Apparent Cause Evaluation (EACE) performed for the 1SI8811B valve stroke failure on
June 24, 2009. The
- EACE identified the apparent cause to be corrosion of the torque switch due to water intrusion into the valve actuator
LS compartment through conduit C1A1454. The licensee identified the open end of the conduit as the probable entry point
for water. The
- EA [[]]
CE report evaluated multiple sources of water to determine the specific
source. The licensee focused on the tritium identified in the water sample, which resulted
in the discounting of roof leakage as a likely source. Therefore, the licensee took no
further action to address the roof leaks that were a probable source of water during the June 24, 2009, water intrusion event. The
- EA [[]]
CE investigation narrowly focused on tritiated water sources and an open upward conduit opening as the likely water intrusion
point. The
CWA roof
leakage that created a larger challenge to the valve and other leakage pathways that
existed for water intrusion into the valve. The licensee's root cause evaluation documented that
EACE performed for the June 24, 2009,
event. One significant conclusion was that the decision-making process for the level of review should consider the risk significance of the components in the licensee's
- PRA [[analysis. c. Determine that the root cause evaluation included a consideration of prior occurrences of the problem and knowledge of prior operating experience. The inspector determined that the root cause evaluation included a consideration of prior occurrences of the problem and knowledge of prior operating experience. Through a review of Operating Experience (OPEX), the licensee identified the following events at other facilities that had a root or contributing cause that was similar to the]]
- WO 006B failed to close and tripped thermal overloads. The actuator motor was found seized due to water intrusion. Water was believed to have originated from condensation on the valve body. St. Lucie 2003 - An
- MOV failed to close on demand due to corrosion and binding of the actuator torque switch. The corrosion was due to water intrusion into the
LS compartment due to a poor seal between the LS compartment cover and the
actuator housing. North Anna 2003 -
- SW -MOV-217 failed to stroke due to tripping of the thermal overloads. An investigation determined that water had entered the
- LS compartment and shorted the torque switch. The water intrusion was traced to a threaded connection in the steel conduit. Farley 2007 - Containment Sump Suction Isolation Valve Q2E11
MOV8811A failed to fully open during testing. This valve also failed to stroke open during an earlier stroke test in 2006. This failure was originally attributed to dirty contacts
that were subsequently cleaned by stroking the valve numerous times. Following
the second event, an investigation determined that the current and previous failures were due to corrosion and binding of the actuator torque switch. The
Enclosure corrosion of the torque switch was due to the valve being inside an enclosure subject to a high humidity environment. The LS compartment was neither sealed
nor otherwise protected from humidity. The root causes were (1) the equipment was not designed for the environment and (2) the torque switch was only bypassed for the first 25 percent of the stroke when it was only needed for the
last portion of the stroke. In addition, the licensee's root cause evaluation documented other Braidwood Station
events relative to water intrusion into
- MOV actuators. Specifically highlighted in the root cause evaluation are the following events that occurred in 1990 and 2002, respectively: Valve 1
SI8809A failed to stroke open due to corrosion of the torque switch causing it to bind and not move freely. Investigation into the cause of the water intrusion found that it was most likely due to draining operations of lines above
the valve. Valve
- 1CS 001A failed to reopen after being closed due to a failure of the torque switch bypass circuit. The apparent cause was that water entered the actuator
LS compartment through the flex conduit. The flex portion of the conduit was too short and the outer jacket of the flex conduit was trimmed such that it did not fully
extend under the sealing ring of the conduit connector. The conduit connector
was also found to be very loose. Valve 1WO029, which was located directly
above Junction Box
- MOV [[]]
- IR s related to roof leaks at Braidwood Station. The licensee did not recognize the significance of the previous
OPEX prior to
the failure of the 1SI8811B valve, but subsequently identified insights for the
development of corrective actions to address the entry points for water intrusion as well
as reducing the vulnerability of equipment that could be impacted from water intrusion. d. Determine that the root cause evaluation addressed extent of condition and the extent of cause of the problem. The inspector determined that the root cause evaluation adequately addressed the extent of condition and extent of cause of the problem. The licensee developed a leakage/spill template for
- IR s associated with liquid leaks/spills as a corrective action to this event. The inspector reviewed several
IRs associated with the use of the leakage template. The inspector also reviewed an
identified vulnerability with licensee personnel and independently applied the
leakage/spill template. The inspector concluded that the leakage/spill template
adequately addressed the potential impact of water intrusion on electrical components.
In addition, the inspector reviewed
AOV [Air-Operated Valve] Assembly Identified During Rebuild," which identified water intrusion into an air-operated containment isolation valve actuator. The inspector determined that the application of
the leakage/spill template to this IR was successful in identifying a potential problem due
to plant leakage and adequately addressed that identified problem prior to any actual
adverse consequences.
Enclosure e. Determine that the root cause, extent of condition, and extent of cause evaluations appropriately considered the safety culture components as described in
Inspection Manual Chapter (IMC) 0305. The inspector determined that, in general, the root cause, extent of condition, and extent of cause evaluations appropriately considered the safety culture components as
described in
CWA roof had been identified prior to the October 30, 2009, event. Based on interviews conducted by the licensee with operators, radiation protection (RP)
technicians, and engineers, the licensee had identified rainwater leaking from the removable concrete roof slabs on both Unit 1 and Unit 2 on other occasions dating back to 1998. The licensee's interviews revealed a general awareness of CWA roof leaks on
Unit 1 and Unit 2 during periods of heavy rains. However, no IRs related to roof leaks
were generated between December 2007 and the October 30, 2009 event. The
licensee's interviews revealed that this occurred because licensee personnel generally believed that IRs were written and work orders were already in the corrective action and work control processes. This demonstrated that when long-standing material condition
issues, such as roof leaks, were not resolved over time, it created a condition in which
individuals were less likely to generate additional IRs for the same issue. This resulted
in a situation where degrading or changing conditions went unreported and existing work orders were not re-prioritized. The licensee's root cause report documented that based on discussions with maintenance personnel in November 2009, the backlog of power-block non-outage
facilities work orders was 1,816. The roof leak IRs described in the root cause
evaluation were among this backlog and resulted in the degradation of the 1SI8811B
valve. The licensee determined that based on the results of an Institute for Nuclear Power Operations (INPO) Safety Culture Assessment conducted in January 2010, no additional
corrective actions in this area were required. The inspector conducted interviews with
two non-licensed operators concerning long-standing material conditions. The concerns
expressed by the non-licensed operators echoed the licensee's original interview responses. The examples provided by the operators of long-standing material condition problems were neither safety-related nor safety significant. The inspector discussed
these interview results with licensee management. The inspector communicated the
concern that a seemingly minor material condition issue may not manifest itself as a safety issue for a very long time. The licensee described actions taken by the station to
prioritize and reduce the backlog. f. Findings No findings of significance were identified.
Enclosure 02.03 Corrective Actions a. Determine that appropriate corrective actions are specified for each root and contributing cause or that the licensee has an adequate evaluation for why no corrective actions are necessary. The inspector reviewed applicable corrective actions and corrective actions to prevent recurrence and determined that the licensee specified appropriate corrective actions for
each root and contributing cause. The inspectors also reviewed implementation of the
corrective actions to verify completion. As part of the corrective actions for this event, the licensee sealed the susceptible conduit. To address extent of condition concerns, the licensee subsequently performed successful valve strokes of the
SI8811A, and 2SI8811B valves as part of
previously scheduled maintenance activities. Additionally, the licensee performed a
walkdown of the
SI8811A, and 2SI8811B valves on both units. Open
conduit terminations were identified on all three of these valves. The
- 2SI 8811B valve was identified to have the same susceptible conduit and cable tray configuration, while the 1
SI8811A and 2SI8811A valves had horizontal conduit terminations that were less
susceptible to water intrusion. As a result, the licensee sealed the 2SI8811B valve open
conduit termination. In addition, the licensee developed a list of MOVs and other electrical components to be inspected, based on their contribution to risk. This list included actions to be performed, such as conduit inspections, and a schedule for performing the work. For susceptible
MOVs, the licensee sealed the associated conduit and/or installed a T-drain into the
bottom of the LS compartment to prevent water accumulation and/or increased the
torque switch bypass setting to 100 percent. The licensee identified the root cause to be that station personnel did not fully understand that the CWA design configuration did not incorporate watertight electrical
components to prevent water intrusion. As a result, station personnel lacked sensitivity
to the effects of water spills, sprays, or leaks in the
MOV actuator design requirements and the need to ensure proper control of water in
areas of the plant not designed for water spray or spills, and (2) implementing processes
and controls to evaluate electrical components affected by potential water intrusion.
In addition, the licensee identified that the
- CWA roof structure did not conform to the existing design drawings and was the probable source of water intrusion into the 1
SI8811B valve. The licensee performed inspections and developed work orders and
schedules to return the CWA roofs to the existing design requirements. The licensee
inspected other safety-related structures with removable hatches for proper installation.
The licensee had completed the work on the CWA roofs and were in the process of performing repairs to the main steam isolation valve room roofs, which were also identified as needing repair, during the inspection.
Enclosure b. Determine that corrective actions have been prioritized with consideration of the risk significance and regulatory compliance. The inspector concluded that the licensee adequately prioritized the corrective actions with consideration of the risk significance and regulatory compliance. c. Determine that a schedule has been established for implementing and completing the corrective actions. The inspector determined that the licensee established a schedule for implementing and completing the corrective actions. The licensee assigned completion due dates that were commensurate with the significance of the issues being addressed as well as the level of effort required to complete the actions. d. Determine that quantitative or qualitative measures of success have been developed for determining the effectiveness of the corrective actions to prevent recurrence. The inspector determined that the licensee adequately developed quantitative or qualitative measures of success for determining effectiveness of the corrective actions to prevent recurrence. The period identified for review by the licensee to determine
corrective action effectiveness had not yet ended at the end of this supplemental
inspection. e. Determine that the corrective actions planned or taken adequately address the Notice of Violation that was the basis for the supplemental inspection. The inspector concluded that the corrective actions planned or taken adequately addressed the Notice of Violation. However, the inspector identified that the licensee's
response to violation 05000456/2009007-001, "Failure of Containment Sump Suction
Valve
- 1SI 8811B to Stroke Open," did not address all regulatory concerns. In particular, the Notice of Violation, as documented in the Final Significance Determination dated February 25, 2010, stated the following: "Title 10
CFR Part 50, Appendix B, Criterion III, Design Control, requires, in part, that measures be established for the selection
and review for suitability of application of materials, parts,
equipment, and processes that are essential to the safety-related
functions of the structures, systems, and components. Contrary to the above, from initial design, measures were not established to ensure the selection and suitability of application of equipment essential to the safety-related function of the residual
heat removal system. Specifically, the design of the 1SI8811B
motor operated valve actuator and associated conduit were not
suitable to the application, because the design allowed water to
enter the conduit and collect inside the actuator. This resulted in the failure of valve 1SI8811B to stroke full open during
Enclosure surveillance testing on June 24, 2009, due to corrosion of the torque switch." The inspector identified that although the licensee's corrective actions sealed the flex conduit, the design change process was not utilized to ensure that the seal would not be
removed in the future; which was a performance deficiency. However, due to the comprehensive nature of the licensee's corrective actions, the inspector determined that this issue was minor since the performance deficiency did not impact the Mitigating
System cornerstone objective to ensure the availability, reliability, and capability of
systems that respond to initiating events to prevent undesirable consequences, or satisfy
any of the other criteria to be considered when assessing the significance of a
performance deficiency. Based on the inspector's concerns, the licensee generated
DCR [Document Change Request]," and completed DCR 381928 to update drawings 20E-1-3312, 20E-1-3314, 20E-2-3312, and 20E-2-3314 to ensure the
seal would not be removed from the conduit in the future. f. Findings No findings of significance were identified.
SI8811B to Stroke Open" The inspector determined that the licensee's root cause evaluation was conducted to a level of detail commensurate with the significance of the problem and reached
reasonable conclusions as to the root and contributing causes of the event. The inspectors also concluded that the licensee identified appropriate corrective actions for each root and contributing cause and that the corrective actions were prioritized
commensurate with the safety significance of the issues. No other instance of the
violation was identified. This violation is closed. 4OA6 Meetings, Including Exit .1 Exit Meeting Summary The inspectors presented the inspection results to Mr. A. Shahkarami and other members of licensee management on November 1, 2010. 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. .2 Regulatory Performance Meeting On November 1, 2010, the
IMC 0305, Section 10.02.b.4. During this meeting, the NRC and
licensee discussed the issues related to the White finding that resulted in Braidwood
Nuclear Power Station, Unit 1 being placed in the Regulatory Response column of the
Reactor Oversight Process (ROP) Action Matrix. This discussion included the causes,
Enclosure corrective actions, extent of condition, extent of cause, and other planned licensee actions.
- ATTACH [[]]
- MENT [[:]]
- SUPPLE [[]]
- MENTAL [[]]
- INFORM [[]]
- SUPPLE [[]]
- MENTAL [[]]
- INFORM [[]]
- ATION [[]]
- KEY [[]]
- POINTS [[]]
- OF [[]]
CONTACT Licensee A. Shahkarami, Site Vice President L. Coyle, Plant Manager
C. Bedford, Program Engineering
P. Boyle, Maintenance Director
- M. Marchionda, Operations Director R. Radulovich, Nuclear Oversight Manager M. Smith, Engineering Director
- NRC [[]]
- K. O'Brien, Acting Deputy Director, Division of Reactor Projects E. Duncan, Branch Chief, Division of Reactor Projects, Branch 3 J. Benjamin, Senior Resident Inspector D. Bentancourt, Resident Inspector
- LIST [[]]
- OF [[]]
- ITEMS [[]]
- CLOSED [[]]
- AND [[]]
DISCUSSED Opened None
Closed 05000456/2009007-01
SI8811B to Stroke Open (Section 4OA5) Discussed None
Attachment
- LIST [[]]
- OF [[]]
- DOCUME [[]]
- NTS [[]]
- REVIEW [[]]
- ED The following is a list of documents reviewed during the inspection. Inclusion on this list does not imply that the
- NRC inspectors reviewed the documents in their entirety, but rather, that selected sections of portions of the documents were evaluated as part of the overall inspection effort. Inclusion of a document on this list does not imply
NRC acceptance of the document or
any part of it, unless this is stated in the body of the inspection report.
- IP 95001, "Inspection for One or Two White Inputs in a Strategic Performance Area" - Letter from M. Satorius, (U.S.
- NRC Inspection Report No. 05000456/2010008; Braidwood Station, Unit 1, February 25, 2010 - Letter from S. West, (U.S.
- PRELIM [[]]
- INARY [[]]
- YELLOW [[]]
- FINDIN G; November 30, 2009 - Root Cause Evaluation 987342, "1SI8811B Valve Failure," Revision 0, November 23, 2009 - Focused Area Self Assessment 1059848-03, "1SI8811B 95001 Inspection Readiness," June 30, 2010 -
AA-115, "Operating Experience Program," Revision 15
-
AA-115, "Operating Experience Procedure," Revision 10
-
ACIT Closure Needs Improvement"
-
AOV Assembly Identified During Rebuild (1RE9159B)
-
DCR"
-
PS9355A"
-
CAPR-2, 987342-19, Corrective Action to Prevent Reoccurrence (Assignment 19)
- CA 987342-1-7, Corrective Action (Assignments 41,41,20,21,22,23,& 44)
-
- ACIT 987342-xx, Action Item (Assignments 11, 12, 24, 25, 29, 30, 31, 33, 14-17, 45-51, 36, 54, 57, & 58) - Work Order 723246-03, "Determ/Reterm In Support of
MMD Actuator Overhaul" - Braidwood Nuclear Station Nuclear Safety Culture Assessment, January 2010
- Braidwood Station Motor Operated Valve Program Status (4th Quarter 2007)
Attachment
- LIST [[]]
- OF [[]]
- ACRONY [[]]
- MS [[]]
- USED [[]]
- EA [[]]
- EC [[]]
CS Emergency Core Cooling System
- IN [[]]
IR Issue Report K-T Kepner-Tregoe
OPEX Operating Experience PRA Probabilistic Risk Assessment
ROP Reactor Oversight Process
SDP Significance Determination Process
VIO Violation
M. Pacilio -2- The inspector determined that your root cause evaluation was conducted to a level of detail commensurate with the significance of the problem and reached reasonable conclusions as to the root and contributing causes of the event. The inspector also concluded that you identified
the extent of condition and extent of cause of the issue, that you identified appropriate corrective
actions for each root and contributing cause, and that you appropriately prioritized these
actions. Based on the results of this inspection, no findings of significance were identified. In accordance with
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 System (PARS) component of
NRC Website at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Sincerely,
/RA by Kenneth G. O'Brien for/
Gary L. Shear, Acting Director
Division of Reactor Projects
Docket No. 50-456 License No. DPR-72
Enclosure: Inspection Report 05000456/2010009
w/Attachment: Supplemental Information cc w/encl: Distribution via ListServ
- DOCUME [[]]
- NT [[]]
- DRPIII \BRAI\BRA 2010 009 95001.docx Publicly Available Non-Publicly Available Sensitive Non-Sensitive To receive a copy of this document, indicate in the concurrence box "C" = Copy without attach/encl "E" = Copy with attach/encl "N" = No copy
- OFFICE [[]]
- RIII [[]]
- RIII [[]]
- RIII [[]]
- NAME [[]]
- RECORD [[]]
- BRAIDW [[]]
- OOD [[]]
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- INSPEC [[]]
- TION [[]]
- REPO [[]]