IR 05000338/2010006
| ML103440476 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 12/10/2010 |
| From: | Gerald Mccoy NRC/RGN-III/DRP/B5 |
| To: | Heacock D Virginia Electric & Power Co (VEPCO) |
| References | |
| IR-10-006 | |
| Download: ML103440476 (22) | |
Text
UNITED STATES ber 10, 2010
SUBJECT:
NORTH ANNA POWER STATION - NRC SPECIAL INSPECTION REPORT 05000338/2010006 AND 05000339/2010006
Dear Mr. Heacock:
On October 15, 2010, the United States Nuclear Regulatory Commission (NRC)
completed the onsite portion of a special inspection at your North Anna Unit 1 and 2 facilities. The inspection reviewed the circumstances surrounding the identification of Microtherm insulation inside the Unit 1 and Unit 2 reactor containments on September 22, 2010, through September 29, 2010. A special inspection was warranted based on the risk and the deterministic criteria specified in Management Directive 8.3, NRC Incident Investigation Program. The determination that the inspection would be conducted was made by the NRC on October 1, 2010, and the inspection started on October 4, 2010. The preliminary inspection results were discussed with you and members of your staff on October 9, 2010. The inspection team conducted subsequent in-office reviews and performed additional onsite inspection during the week of October 11, 2010. The enclosed inspection report documents the inspection results which were discussed via telephone with Mr. Larry Lane and other members of his staff on November 1, 2010.
The inspection was performed in accordance with Inspection Procedure 93812, Special Inspection, and focused on the areas discussed in the inspection charter described in the report. The inspection examined activities conducted under your license as they relate to safety, compliance with the Commissions rules and regulations, and with the conditions of your license. The team reviewed selected procedures and records, conducted field walk downs, observed licensee activities, and interviewed personnel.
Based on the results of this inspection, no findings of significance were identified. In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS)
VEPCO 2 component of NRCs 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/
Gerald J. McCoy, Chief Reactor Projects Branch 5 Division of Reactor Projects Docket Nos.: 50-338, 50-339 License Nos.: NPF-4, NPF-7
Enclosure:
Inspection Report 05000338, 339/2010006 w/Attachment: Supplemental Information
REGION II==
Docket No.: 50-338, 50-339 License No.: NPF-4, NPF-7 Report No.: 05000338/2010006, 05000339/2010006 Licensee: Virginia Electric and Power Company (VEPCO)
Facility: North Anna Power Station, Units 1 and 2 Location: 1022 Haley Drive Mineral, VA 23117 Dates: October 4, 2010 through October 15, 2010 Examiners: Eddy Crowe, Senior Resident Inspector, Farley (Lead)
Jason Eargle, Reactor Inspector Approved by: Gerald J. McCoy, Chief Reactor Projects Branch 5 Division of Reactor Projects Enclosure
SUMMARY OF FINDINGS
IR 05000338/2010006, 0500339/2010006; 10/04/2010 - 10/15/2010; North Anna Power Station,
Units 1 and Unit 2; Special Inspection.
This report documents special inspection activities performed onsite and in the Region II office by one senior resident inspector and one reactor inspector to review the circumstances surrounding the licensees identification of Microtherm insulation inside Unit 1 and Unit 2 containments on September 22, 2010, through September 29, 2010. 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.
NRC-Identified and Self-Revealing Findings
No findings
Licensee-Identified Violations
No findings
REPORT DETAILS
Summary of the Degraded Condition On September 22, 2010, while Unit 1 was shutdown for a refueling outage, engineers at the North Anna Power Station identified that Microtherm insulation may be installed inside the Unit 1 containment on the reactor pressure vessel nozzles. The licensees analysis for debris generation due to a loss of coolant accident (LOCA) did not account for any Microtherm insulation inside the containment building. This analysis was the basis for the licensees submittal to the NRC in response to Generic Letter (GL) 2004-02. Based on this discovery, the licensee performed further inspections which identified the potential that Microtherm insulation was also installed in other locations within both the Unit 1 and Unit 2 containments. Unit 2 was shutdown on September 29, 2010, in order to investigate the potential presence of Microtherm insulation. Inspections subsequently confirmed the presence of Microtherm insulation in both Unit 1 and Unit 2 containments. The licensee has performed additional inspections of each containment, identified potential locations of undesired insulation and performed remediation.
The licensees efforts resulted in the removal of all Microtherm and Cal-Sil insulation from the zones of influence (ZOI). Insulation left in areas not within the ZOI were inspected to verify the insulation was properly installed.
Inspection Scope Based on the deterministic and conditional risk criteria specified in Management Directive 8.3, NRC Incident Investigation Program, a special inspection was initiated in accordance with NRC Inspection Procedure 93812, Special Inspection Team. The inspection focus areas included the following special inspection charter items:
1. Develop a sequence of the events leading to discovery of Microtherm insulation inside
containment.
2. Review the methodology used by the licensee to develop their response to GL 2004-02;
specifically assess why the licensee did not identify the presence of unanalyzed insulation inside containment.
3. Review the adequacy of the licensees efforts to identify all the unanalyzed insulation
inside containment subsequent to this discovery.
4. Review the licensees corrective actions to address unanalyzed insulation in
containment. As applicable, review any modifications the licensee developed for removal of Microtherm insulation in containment.
5. Identify any potential generic safety issues, and make recommendations for appropriate
follow-up action (e.g., Information Notices, GLs, and Bulletins).
OTHER ACTIVITIES
4OA5 Other Activities - Special Inspection
.01 Sequence of Events (Charter Item 1)
The inspectors developed two timelines for this inspection. The first timeline describes the licensees major activities related to their response to GL 2004-002. The second timeline describes licensee activities leading to the discovery of Microtherm insulation on the reactor vessel nozzles in Unit 1.
GL 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors, was issued on September 13, 2004. This GL requested that addressees perform an evaluation of the emergency core cooling system (ECCS) and containment spray system (CSS) recirculation functions.
The GL also requested that licensees take any additional actions required to ensure system functionality. The request was based on the identified potential susceptibility of pressurized-water reactor (PWR) recirculation sump screens to debris blockage during design basis accidents requiring recirculation operation of ECCS or CSS, and on the potential for additional adverse effects due to debris blockage of flow-paths necessary for ECCS and CSS recirculation and containment drainage. The GL required a written response to the NRC. Prior to the issuance of the GL, Virginia Electric and Power Company (VEPCO) was involved with other members of the industry to develop a methodology to address these concerns.
Licensee Activities Related to GL 2004-002 Prior to Spring, 2003 The licensee participated in NEI workshops related to the Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors Initiative.
Spring, 2003 VEPCO established a contract with Enercon Services Inc. (Enercon) to perform inspections in each containment to identify insulation, potential debris, and other items which could transport to the containment sumps. Enercon performed Unit 1 containment walkdowns in the spring of 2003. This effort was performed in accordance with the guidance contained in NEI 02-01, and documented in Enercon report DOM001-RPT-001 dated June 24, 2003.
Spring, 2004 Enercon performed a Unit 2 containment walkdown to identify insulation, potential debris, and other items which could transport to the containment sumps. This effort was also performed in accordance with the guidance contained in NEI 02-01 and documented in Enercon report DOM001-RPT-004 dated January 24, 2005.
September, 2004 The NRC issued GL 2004-002, on September 13, 2004, in which the licensees were requested to perform a mechanistic evaluation of the potential for the adverse effects of post-accident debris blockage and operation with debris-laden fluids which may impede or prevent the recirculation functions of the ECCS and CSS following any postulated accidents. Licensees were allowed to use alternative methodologies to those already approved by the NRC; but additional staff review may be required to assess the adequacy of such approaches. The licensees were required to implement any plant modifications that were identified as being necessary to ensure system functionality. All actions were to be completed by December 31, 2007.
December, 2004 The NRC issued a Safety Evaluation Report for NEI 04-07, Pressurized Water Reactor Containment Sump Evaluation Methodology.
December, 2005 The licensee issued calculation ME-0779, Debris Generation Due to LOCA within Containment for Resolution of GSI-191. This document described the debris generation analysis using NEI 04-07 guidance, and became an input to the Atomic Energy Canada Limited (AECL) testing program for the evaluation of the proposed North Anna recirculation spray (RS) and low head safety injection (LHSI) containment sump strainers.
August, 2006 AECL testing of the North Anna debris loading identified Calcium Silicate (Cal-Sil) and Microtherm insulation as particulate materials whose presence may produce debris-induced head losses above the allowable values for the RS and LHSI containment sump strainers. North Anna decided to remove Cal-Sil and Microtherm insulation identified in the postulated break ZOI as part of the GSI-191 resolution.
Spring, 2007 VEPCO implemented design change (DC)07-004 to remove previously identified Cal-Sil and Microtherm insulation from Unit 2. VEPCO also implemented DC 05-014 to install the modified containment sump strainers in Unit 2.
Fall, 2007 VEPCO implemented DC 07-129 to remove previously identified Cal-Sil and Microtherm insulation from Unit 1. VEPCO also implemented DC 05-013 to install the modified containment sump strainers in Unit 1.
February, 2008 VEPCO letter 08-0019 documented completed actions to resolve GL 2004-02, except for chemical, downstream, and in-vessel effects. Chemical effects analysis and strainer testing on AECL Rig 89 was performed without the presence of Microtherm insulation.
February, 2009 VEPCO submitted letter 09-003 on February 27, 2009 to update their response to GL 2004-02. This letter contained information to address the analysis performed and corrective actions taken that were not complete at the time VEPCO letter 08-0019 was submitted. The NRC acknowledged and accepted the licensees response in a letter dated May 28, 2009.
Discovery of Microtherm Insulation April 17, 2010 Licensee personnel identified a small boric acid leak from the temporary cavity seal ring in the inner annulus area on Unit 2. The licensee recognized the need to remove the neutron shielding material on the reactor vessel nozzles on both units to perform additional boron inspections. A request for engineering assistance was generated to develop a resolution.
September 13, 2010 Licensee personnel performed an inspection of the inner annulus area on Unit 1 and discovered the neutron shielding material damaged and wrote condition report (CR)394466.
September 22, 2010 The licensee prepared DC 10-00154 to address the improperly configured neutron shielding material. Part of those preparations involved a review of DC 79-S07 which was the licensees design change package for the installation of supplementary neutron shielding. DC 79-S07 indicated the potential that Microtherm insulation was installed at this location. The preparer had been involved in the GSI-191 program, which is the licensee Debris and Surrogate Materials for use in Head Loss Testing of Containment Sump Screens for Millstone, Surry, and North Anna. This preparer recognized the significance of Microtherm insulation in the ZOI. This prompted the licensee to perform a review of the original walkdown reports performed by Enercon in 2003 and 2004, material specifications, design changes, and station drawings. This review determined the potential for the presence of additional Microtherm insulation in Unit 1 and Unit 2.
September 24, 2010 Microtherm insulation was discovered on each of the Unit 1 intermediate leg elbows closest to the reactor coolant pumps (RCP). The licensee entered this in its corrective action program (CAP) as CR 396377. The licensee performed a review of DC 07-004 and found evidence that Microtherm had been removed from this location on Unit 2.
September 28, 2010 The licensee discovered Microtherm insulation on each Unit 1 RCP casing, and licensee entered this in its CAP as CR 396823. The licensee could not identify that Microtherm had been removed from this location in Unit 2. Unit 2 was shutdown to support inspections to search for the presence additional Microtherm insulation.
September 29, 2010 Microtherm insulation was identified on each of the Unit 2 RCP casings. The licensee entered this in its CAP as CR 396992.
October 4, 2010 NRC inspectors arrived onsite at North Anna units to begin special inspection activities.
These activities include observation of licensee activities to remove Microtherm insulation from Unit 2 containment, review of the licensees methodology to ensure all insulation of concern is removed from both units, and evaluation of the thoroughness of the licensees corrective actions since the issue was discovered.
.02 Review the methodology used by the licensee to develop its response to GL 2004-02;
specifically assess why the licensee did not identify the presence of unanalyzed insulation inside containment. (Charter Item 2)
a. Inspection Scope
The licensees methodology included an evaluation of the potential for adverse effects of post-accident debris blockage and debris-laden fluids to prevent the recirculation functions of the ECCS and CSS systems. The evaluation considered postulated design basis accidents for which the recirculation of the ECCS and CSS systems is required.
The following areas were evaluated:
- Break selection - identified the size and location that presented the maximum debris loading for the design of the strainer
- Debris generation/zone of influence - the zone in which break jet forces would be sufficient to damage materials and create debris and the amount of debris generated by the jet forces
- Debris characteristics and transport - determine the fraction of debris generated that would reach the sumps
- Latent debris - determine the type and amount of debris available for transport to the sumps
- Containment coating - identified qualified and unqualified coatings within a 10 diameter zone of influence for debris generation
- Laboratory testing to validate head loss, strainer vortexing, and structural analysis
The above activities lead to the development of seven corrective actions or modifications.
- Installation of two new containment sump strainers to increase the total surface area.
- Removal of Calcium-Silicate (Cal-Sil) insulation located within the steam generator cubicles and pressurizer room.
- Removal of Microtherm insulation from Unit 2 containment. (Microtherm insulation had been identified as not being installed in Unit 1 containment)
- Installation of a drain in the primary shield wall to the incore sump room.
- Addition of a start circuit for the recirculation spray system pump on a containment depressurization actuation signal coincident with a refueling water storage tank low level signal.
- Modification of the refueling water storage tank level instrumentation setpoints to allow more inventory for the containment sumps.
- Modification of the containment sump level transmitters to protect them from clogging due to debris.
The team reviewed the licensees corrective actions associated with the removal of Cal-Sil and Microtherm insulation in order to identify why the licensee failed to identify the Cal-Sil and Microtherm insulation subsequently discovered in September 2010. The team reviewed the licensees design change documents (DC 07-004 and DC 07-129)that mitigated the above insulation to evaluate how they were developed. These DCs were developed from Enercon containment walkdown reports generated from the activities in 2003 and 2004. The team evaluated the VEPCO resources utilized by Enercon to perform these walkdowns. The team evaluated the contents of these walkdown reports for thoroughness and completeness. The team reviewed licensee documents generated from the walkdown reports and implementation of the DCs.
Those documents included:
- DOM-NA-002-PR-001, Validation of the Enercon Walk-down of North Anna
- ET-NPD-CME-06-007, Evaluation of Insulation Inside Containment for Resolution of GSI-191
- NA-CALC-MEC-ME-0780, Post LOCA Debris Transport to Containment Sump Strainer for Resolution of GSI-191
- NA-CALC-MEC-ME-0779, Debris Generation Due to LOCA With Containment for Resolution of GSI-191, Revision 1 and Revision 2.
DOM-NA-002-PR-001 reconciled the discrepancies discovered during the implementation of DC 07-004 and DC 07-129. ET-NPD-CME-06-007 provided an evaluation of the particulate piping insulation within containment for resolution of GSI-191. The document identified that particulate piping insulation requiring replacement for GSI-191 analysis to meet design requirements, and the recommended insulation material to use as a replacement. NA-CALC-MEC-ME-0780 and NA-CALC-MEC-ME-0779 tracked the remediation efforts for particulate piping insulation within containment.
Additionally, the team reviewed ET-N-08-0045, Additional Drawings for Verification of Enercon GSI-191 Insulation Inventory and Technical Report ME-0190, Validation of Enercon Walkdown for North Anna for additional assurance that was no additional evidence of Microtherm insulation in containment.
b. Observations The team concluded that the licensees management oversight of the project to identify potential debris issues with containment sump strainers of both units was not thorough.
The team noted that Enercon had not been provided a complete set of insulation drawings, which inhibited their ability to identify Microtherm insulation during their containment walkdowns. The team discovered that reflective metal insulation and jacketed Microtherm insulation have a similar outward appearance and noted that Enercon misidentified some insulation as reflective metal insulation. Two VEPCO station personnel were assigned to the vendor team performing the containment walkdowns. The NRC team noted that these individuals were to assist the vendor team and had knowledge of station documents and insulation installation to aid the containment walkdown efforts. The NRC team concluded that the above issues contributed to the failure to accurately identify the insulation contained in containment during the containment walkdowns. The team concluded that this was the first missed opportunity for VEPCO to identify entire volume of Cal-Sil and Microtherm insulation within each containment prior to their GL 2004-02 response. Additionally, the team noted that a more complete set of insulation drawings could have been made available for the Enercon walkdown. Just prior to the NRC team arriving onsite, the licensee contacted their insulation vendor and obtained a complete set of insulation drawings.
VEPCO relied upon these insulation drawings during their September - October, 2010 corrective actions and the drawings accurately indicated the presence of all additional Microtherm insulation.
While implementing DC 07-004 and DC 07-129 to remove undesired insulation from the Unit 1 and Unit 2 containments VEPCO identified discrepancies in the Enercon walkdowns. The team found that discrepancies existed between these DCs and the Enercon walkdown reports. The team did not find any CRs, reports, or other documentation in which VEPCO personnel questioned the validity of these walkdown reports. The team found that VEPCO did submit those discrepancies to Enercon for inclusion in their 2008 report, DOM-NA-002-PR-001, Validation of the Enercon Walkdown of North Anna. Enercon included these discrepancies in its report, and VEPCO used the report to develop its responses to GL 2004-02. The team concluded that this was the second opportunity to discover the lack of a thorough evaluation of the insulation within each containment.
.03 Review the adequacy of the licensees efforts to identify all the unanalyzed insulation
inside containment subsequent to this discovery. (Charter Item 3)
a. Inspection Scope
The team interviewed station personnel and reviewed available station documents related to the licensees efforts to identify and remove Cal-Sil and Microtherm insulation from Unit 1 and Unit 2 containments subsequent to the discovery in September 2010. The inspectors also reviewed selected CRs and work orders to independently assess the conclusions and recommended actions from the licensees investigation. The team observed insulation inspections while in progress in containment to verify the type of insulation installed.
The team observed the licensee performing the spot checks of piping segments in containment. The team observed the licensee visually inspect the piping segment for potential areas that may contain discrepant insulation. The licensee then inspected these areas by peeling back a section of the metal jacket to see the insulation below.
During the more detailed inspection during the second week, the licensee developed procedures to perform a complete verification of the small bore piping (< 27 diameter) in the ZOI of Unit 1 and Unit 2 containment. The team determined that the licensee was adequately training and briefing individuals to perform these inspections. The team observed that the licensee personnel followed the inspection procedures, and that any discrepant insulation found during these inspections was removed.
b. Observations The team found that the licensee conducted an initial informal evaluation of the insulation discrepancies found in containment. A subsequent formal root cause evaluation is planned by the licensee following remediation of the discrepant insulation.
The informal evaluation identified three causes and implemented the corrective actions listed below:
1) The licensee discovered that Enercon did not use a complete set of design documents during the initial insulation walkdowns. During the initial walkdowns in 2003 and 2004, Enercon was provided a partial set of insulation drawings referred to as the Transco drawings. Transco was the insulation vendor for the reactor coolant system (RCS) during construction of each unit. The licensee addressed this weakness by obtaining a complete set of insulation drawings from Transco. These drawings were reconciled with information contained in the GSI-191 database.
Locations identified on the Transco drawings as containing Microtherm insulation for which there was no engineering documentation for remediation were inspected.
Microtherm insulation was found in each case where it was indicated on the complete set of Transco drawings.
2) The licensee identified that Enercon did not completely inspect each containment during the walkdowns in 2003 and 2004 due to radiological concerns and ease of access. Areas not inspected included the reactor cavity annulus/keyways, the reactor vessel and vessel head, the regenerative heat exchanger room, and the refueling canal. To address this omission, the licensee performed visual inspections in each of the first three areas (the refueling canal was determined to contain no insulation), and discovered Microtherm insulation in the regenerative heat exchanger room and on the reactor vessel nozzles. Cal-Sil insulation was also discovered on the reactor vessel leak-off flange line in the reactor annulus area. All Microtherm and Cal-Sil insulation which was discovered was removed and replaced with a suitable insulation or evaluated to allow no insulation to be installed.
3) The licensees initial review of engineering documents revealed the third cause in which some identification and administrative errors were made with the reconciliation and remediation of identified Microtherm and Cal-Sil insulation. In some instances Microtherm insulation was not recognized when directly observed by the remediation team. To address this weakness, the licensee inspected all small bore piping (<27 diameter) in the RCS loop rooms, pressurizer cubicle, and pressurizer spray line, and remediated all discrepant material.
The team discovered the above efforts led to the discovery of discrepant insulation on the reactor vessel nozzles, the bowls of the RCPs, the RCS cold leg bumpers, the pressurizer spray line, pressurizer surge line (Unit 1 only), the RHR/RCS hot leg suction line for RCS loop A, the regenerative heat exchanger (Unit 2 only), and the reactor vessel flange leak-off line on both units.
During the onsite weeks, the team interviewed and observed personnel involved in the spot checks which were intrusive inspections of suspect areas. This inspection involved licensee personnel taking Transco insulation drawings into the containment and performing intrusive visual inspections of suspected sites to verify the type of insulation at each site. From these interviews, the team learned that Microtherm insulation has a high insulating rating and is used in areas with limited space. This attribute aides in the identification of Microtherm insulation and was used by the licensee during their inspections of selected areas. The licensee first visually inspected the piping segment for potential areas that may contain discrepant insulation (different diameter or areas containing whip restraints). The licensee interrogated these areas by peeling back a section of the metal jacket to see the insulation below. On long lengths of piping, the licensee selected random spots along the length to verify the makeup of the insulation was as expected. The licensee performed spot checks on 311 piping segments in Unit 2, and 324 piping segments in Unit 1.
During the second onsite week, the licensee had expanded the scope of their efforts to identify and remediate the discrepant material from the ZOI inside the RCS loop rooms, pressurizer cubicles, and pressurizer spray lines. The licensee developed and implemented procedures to perform a complete verification of the small bore piping (<
27 diameter) in the ZOIs of Unit 1 and Unit 2 containment. These procedures required the licensee to verify the insulation type to the bare pipe by either removal of the insulation or visual cross-section identification. In addition to the increased scope of the insulation inspections, the licensee developed a procedure to perform a post inspection audit of the small bore piping that was inspected. The licensee developed and implemented a procedure to reconcile the applicable station and/or vendor insulation drawings. The inspectors observed a sample of the small bore piping inspections including the pre-evolutionary brief.
The inspectors noted that the licensee performed a review of engineering documents to provide assurance the above activities identified all areas with discrepant insulation.
The licensee reviewed engineering documents and databases to identify potential piping segments that may have been missed. The documents and databases included:
engineering and design change reports, Stone & Webster documents used during the original construction, North Anna design change program documents (DCPs) contained in their DCP database, a review of inconsistencies found within the Enercon validation reports, and comparison of their equipment database to their GSI-191 database. This review did not result in the identification of additional discrepant insulation.
The inspectors concluded the licensees methodology was adequate and should result in the removal of all discrepant insulation in the ZOI of influence.
c. Findings
Introduction:
The team identified an issue of concern regarding the thoroughness of the licensees actions to remove all Cal-Sil and Microtherm particulate insulation from both units containments inside the ZOI to meet the planned design for the recirculation spray and low head safety injection containment sump strainers.
Description:
In August 2006, Atomic Energy Canada Limited (AECL) performed testing of potential containment debris loading. Cal-Sil and Microtherm insulation produced debris-induced head losses above the allowable values for the planned design for the RS and LHSI containment sump strainers. VEPCO implemented DC 07-004 in the spring, 2007 to remove Cal-Sil and Microtherm insulation from Unit 2 and also implemented DC 05-014 to install the modified containment sump strainers. VEPCO implemented DC 07-129 in fall 2007 to remove undesired insulation from Unit 1, and DC 05-013 to install modified containment sump strainers. On February 29, 2008, VEPCO submitted a supplemental response for North Anna Units 1 and 2 for NRC GL 2004-02.
The submittal included a list of corrective actions including the removal of all Microtherm insulation from Unit 2. Unit 1 was identified as having no Microtherm insulation inside containment. In November 2008 VEPCO implemented and completed field changes to DC 05-013 (Unit 1) and DC 05-014 (Unit 2) to update the North Anna licensing basis to meet the requirements of with GL 2004-02 (except for in-vessel effects). The NRC reviewed and accepted VEPCOs response to GL 2004-02 with the exception of in-vessel effects in a letter dated May 28, 2009.
The team did not identify an immediate safety concern for this issue of concern because both units were shutdown at the time of this inspection activity. The team monitored licensee activities during the inspection weeks and noted these activities were focused on the removal of all the Microtherm insulation identified in both units. The team determined that the licensee has performed a reasonable search to identify Cal-Sil and Microtherm insulation inside containment and has either removed the insulation or properly analyzed leaving it in containment.
The team determined additional inspection was required to determine if a performance deficiency existed. In order to properly disposition this issue of concern, additional inspection would be required to better understand: 1) the licensees formal cause determinations for how both Cal-Sil and Microtherm insulation in both units was originally missed; 2) planned licensee corrective actions to address any potential programmatic issues identified in the formal cause determinations; 3) NRC reliance on correspondence between NRC and VEPCO related to GL-2004-02; and 4) NRC understanding of the licensees design as documented in the current Safety Evaluation Report for North Anna Units 1 and 2. This issue of concern was identified as URI 05000338/339/2010006-01, Failure to Remove Particulate Insulation to Meet Strainer Performance Requirements.
.04 Review the licensees corrective actions to address unanalyzed insulation in
containment. As applicable, review any modifications the licensee developed for removal of Microtherm insulation in containment. (Charter Item 4)
a. Inspection Scope
The team obtained copies of all the CRs written prior to and during the inspection weeks, related to the discovery of Microtherm insulation in containment. The team interviewed station personnel about the removal of Microtherm insulation in containment and its replacement with suitable insulation. The inspectors reviewed a sample of the design packages to determine if the licensee was appropriately replacing all insulation with suitable insulation. The team also observed the licensee performing inspections, and remediating discrepant insulation.
b. Observations The team observed evidence that any discovery of Microtherm or Cal-Sil insulation in the containment of either unit was being captured in the licensees CAP. The team reviewed a sample of the CRs and noted that the licensee had not identified corrective actions or cause determinations. The team also noted the licensee had developed interim corrective actions which removed any discrepant insulation discovered. The team also noted the licensee planned a root cause determination. The completed root cause and additional CRs are identified as needing NRC review during the closure of the URI listed in Section 03.
The team observed that the licensee had developed a design package for each site requiring remediation at the time of the inspection. The completed DCP that the team reviewed used Tempmat to replace the Microtherm insulation on the RPV nozzles.
The team recognized that the Tempmat insulation was not as thermally efficient as Microtherm insulation. The team was concerned about the tracking of the increased heat loading inside containment and engaged the licensee. The team found that the licensee considered these to be minor increases in heat load, and were not tracking the increased loading. The team reviewed the design basis document for the Containment Ventilation System to evaluate how this minor increase in containment heat loading may challenge the system. These subsystems, in combination with the RCP motor coolers, provide sufficient cooling capacity to maintain primary containment average air temperature below 120 degrees F during normal sub-atmospheric operation as required by Technical Specifications. The team came to the conclusion the Tempmat insulation did not significantly impact the containment heat loading and assumptions of the safety analysis.
.05 Identify any potential generic safety issues and make recommendations for
appropriate follow-up action (e.g., Information Notices, GLs, and Bulletins). (Charter Item 5)
a. Inspection Scope
The inspectors reviewed the licensees CRs and design documents related to insulation and debris generation to determine the potential for generic safety issues related to the Cal-Sil and Microtherm insulation discovered in containment.
b. Findings
No findings were identified. Based on the information reviewed, the team did not identify any generic safety issues.
4OA6 Meetings, Including Exit
On October 9, 2010, the special inspection team leader presented the preliminary inspection results to Mr. Larry Lane and members of his staff. Subsequently, additional in-office reviews were conducted and the final inspection results and preliminary significance determination were discussed by telephone with Mr. Larry Lane and members of his staff on November 1, 2010. The licensee acknowledged the inspection findings. No proprietary information is included in this inspection report.
ATTACHMENT:
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee Personnel
- M. Crist, Plant Manager
- B. Evans, Radiation Protection Manager
- B. Gaspar, Supervisor Nuclear Engineering
- E. Hendrixson, Director Nuclear Engineering
- T. Huber, Director Engineering
- P. Kemp, Manager Operations Licensing
- D. Knee, Supervisor Nuclear Engineering
- L. Lane, Site Vice President
- D. Llewellyn, Project Manager Nuclear Training
- F. Mladen, Director SS&L
- G. Modzelewski, Manager Nuclear Design Engineering
- S. Morris, Supervisor Nuclear Engineering
- B. Stanley, Oversight Manager
- D. Taylor, Supervisor Licensing
NRC Personnel
- R. Clagg, Resident Inspector
- G. McCoy, Branch Chief
- J. Reece, Senior Resident Inspector
LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED
Opened and Closed
None
Closed
None
Opened
- 05000338/339/2010006-01 URI Failure to Remove Particulate Insulation to Meet Strainer Performance Requirements