ML13301A653
| ML13301A653 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 11/12/2013 |
| From: | Siva Lingam Plant Licensing Branch II |
| To: | James Shea Tennessee Valley Authority |
| Lingam S | |
| References | |
| TAC MF0176, TAC MF0177 | |
| Download: ML13301A653 (8) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 November 12, 2013 Mr. Joseph W. Shea Vice President, Nuclear Licensing Tennessee Valley Authority 1101 Market Street LP 3D-C Chattanooga, TN 37402
SUBJECT:
SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2- AUDIT REPORT REGARDING SEISMIC WALKDOWNS TO SUPPORT IMPLEMENTATION OF NEAR-TERM TASK FORCE RECOMMENDATION 2.3 RELATED TO THE FUKUSHIMA DAI-ICHI NUCLEAR POWER PLANT ACCIDENT (TAC NOS. MF0176 AND MF0177)
Dear Mr. Shea:
On March 12, 2012, the U.S. Nuclear Regulatory Commission (NRC) staff issued a request for information letter per Title 10 of the Code of Federal Regulations, Subpart 50.54(f) (50.54(f) letter). The 50.54(f) letter was issued to power reactor licensees and holders of construction permits requesting addressees to provide further information to support the NRC staff's evaluation of regulatory actions to be taken in response to lessons learned from Japan's March 11, 2011, Great Tohoku Earthquake and subsequent tsunami. The request addressed the methods and procedures for plants to conduct seismic and flooding hazard walkdowns to identify and address degraded, nonconforming, or unanalyzed conditions through the corrective action program, and to verify the adequacy of the monitoring and maintenance procedures.
By letter dated November 27, 2012, as supplemented by letter dated October 4, 2013, Tennessee Valley Authority (TVA or the licensee) submitted Seismic Walkdown Report as requested per Enclosure 3 of the 50.54(f) letter for the Sequoyah Nuclear Plant, Units 1 & 2. On August 27- 29, 2013, an NRC audit team performed an on-site audit to gain a better understanding of the methods and procedures used by TVA to conduct the seismic walkdowns and facilitate the NRC staff review of the walkdown report. The audit report is enclosed.
J Shea If you have any questions, please contact Siva P. Lingam, at 301-415-1564 or by e-mail at Siva.Linqam@ nrc.gov.
Sincerely,
~f*~
Siva P. Lingam, Project Manager Projects Licensing Branch 112 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328
Enclosure:
Audit Report cc w/encl: Distribution via Listserv
REPORT OF REGULATORY AUDIT ON AUGUST 27 TO AUGUST 29, 2013, SEISMIC WALKDOWNS TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNITS 1 & 2 DOCKET NOS. 50-327, 50-328 BACKGROUND On March 12, 2012 (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML12056A046), the U.S. Nuclear Regulatory Commission (NRC) staff issued a request for information letter per Title 10 of the Code of Federal Regulations, Subpart 50.54(f)
(50.54(f) letter). The 50.54(f) letter was issued to power reactor licensees and holders of construction permits requesting addressees to provide further information to support the NRC staff's evaluation of regulatory actions to be taken in response to lessons learned from Japan's March 11, 2011, Great Tohoku Earthquake and subsequent tsunami. The request addressed the methods and procedures for plants to conduct seismic and flooding hazard walkdowns to identify and address degraded, nonconforming, or unanalyzed conditions through the corrective action program, and to verify the adequacy of the monitoring and maintenance procedures.
By letter dated November 27, 2012 (ADAMS Accession No. ML123420152), as supplemented by letter dated October 4, 2013 (ADAMS Accession No. ML13282A232), Tennessee Valley Authority {TVA or the licensee) submitted a Seismic Walkdown Report as requested per of the 50.54(f) letter for the Sequoyah Nuclear Plant (SQN), Units 1 and 2. On August 27 - 29, 2013, the NRC audit team (NRC staff and its contractors) conducted an on-site audit to gain a better understanding of the methods and procedures used by TVA to conduct the seismic walkdowns and facilitate the NRC staff review of the walkdown report.
REGULATORY AUDIT BASIS The NRC staff conducted a regulatory audit to gain a better understanding of the methods and procedures used by TVA to conduct the seismic walkdowns at SQN, Units 1 and 2 and facilitate NRC staff review of the walkdown report.
The guidance for performing the seismic walkdowns was developed by the Electric Power Research Institute (EPRI) with extensive review and input from NRC staff in numerous public meetings, webinars, and public conference calls during its development. The EPRI submitted EPRI-1025286, "Seismic Walkdown Guidance for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Seismic" (walkdown guidance, ADAMS Accession No. ML12164A181) for endorsement, and the NRC staff subsequently endorsed the walkdown guidance by letter dated May 31, 2012 (ADAMS Accession No. ML12145A529). By letter dated July 10, 2012 (ADAMS Accession No. ML12193A509), TVA indicated that they would utilize the NRC endorsed guidance in the performance of the walkdowns at SQN, Units 1 and 2.
Enclosure
The 50.54(f) letter and the walkdown guidance were used as the basis documents upon which the regulatory audit was performed.
AUDIT ACTIVITIES The NRC audit team consisted of James lsom (NRC/Office of Nuclear Reactor Regulation),
Rebecca Karas (NRC/Office of New Reactors [NRO]), Frankie Vega (NRO), Pravin Patel (NRO), Wesley Deschaine (NRC/Region II) and David Ma (Argonne National Laboratory-contractor). The audit was performed from August 27 to August 29, 2013.
The audit team reviewed the following types of information:
- Pre-Audit self-assessment report.
- Hard copies of the in-field seismic walkdown and area walk-by checklists.
- Training records - including certificates of completion and training procedures.
- Updated Final Safety Analysis Report Sections 2.5, 3.7, 3.8 and 3.1 0.
- Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities reports.
- Updated tables with all the identified potentially adverse seismic conditions (PASCs) during the seismic walkdown activities for Units 1 and 2. The table included service request (SR), problem evaluation report and work order (WO) numbers including resolution dates.
- Complete documentation and resolution packages for all the identified PASCs
- Spent fuel pool cooling system configuration drawings.
- Complete package documenting the replacement of bolts to a higher quality for shutdown transformer 1A1-A 6900-480-V 175 to resolve IPEEE outlier condition. This documentation includes the completed corrective action program (CAP) resolution including updated drawings and licensing basis evaluation calculations.
WO No. 113703932 was issued to resolve this issue.
- SRICAP documentation for 10 issues identified during the walkdowns but not considered as PASCs.
- SR-772631 -documentation showing the resolution and updated design drawings for the condition in which the plate/angle connection and attachment bolts were missing that connected the diesel generator skid assembly.
- Temporary Equipment Control Procedure- 0-TI-DXX-00-013.0.
The NRC staff performed an independent review of selected items and areas based on the licensee's walkdowns. The team observed and discussed the following conditions with the licensee to further understand the licensee's overall walkdown processes.
- Essential Raw Cooling Water (ERCW) Pumping Station - Equipment Identification (I D) -
B-B-SQN-0-PMP-067-0477 (ERCW Screen Wash Pump B-B)- The NRC staff verified the condition previously identified by the licensee's seismic walkdown engineers (SWEs), which included a rear anchor bolt nut that did not have full thread engagement with the anchor bolt. It was estimated that it had 75 percent engagement. While performing this independent walkdown the NRC staff also noted that another bolt had less than 100 percent thread engagement. This condition was discussed with the SWEs
at the moment and it was determined not to be a PASC based on engineering judgment.
The licensee later described to the audit team that the issue was reviewed through an informal discussion and provided the engineering basis for acceptance. This item was also reviewed by the peer review team {licensee's staff and its contractors) and their basis was provided as part of the peer review report in accordance with the seismic walkdown guidance.
- Diesel Generator 1A-A Building o Diesel Generator Room Exhaust Fan- Equipment ID- SQN-1-FAN 030-0451-A
-The NRC staff verified there were missing washers that were identified as part of the walkdown for this item. Based on discussions during the audit, the licensee stated that the drawing for the fan housing mounting bolts do not require washers when there is no clearance or gap between the bolt and bolt hole, and mounted to flat flange of the fan skid. Since this condition was in accordance with the design drawing reviewed by the NRC audit team, it was considered acceptable.
o Diesel Generator Room Exhaust Fan- Equipment ID AHU [Air Handling Unit]
-030-455 (Battery hood exhaust fan)- During the NRC staff's walkdown of Diesel Generator 1A-A room, it was noted that a bolt appeared to be missing from the anchorage supporting the fan duct work for 1-AHU-030-455. The NRC staff discussed this potential seismic interaction condition with the licensee. The licensee stated that the design drawing was verified, which showed the bolt was not needed since it had been replaced with a weld connection. This is normal practice when an embedded plate is located at the bolt location. Since this condition was in accordance with the design drawing, it was considered acceptable.
o Equipment ID- SQN-1-ENG-082-000IA 1 -The NRC staff verified a previously identified condition in which a plate connection was missing that connected the diesel generator and engines. According to the licensee, the skid assembly drawing for the generator and engines shows the skids being connected via a plate/angle connection and attachment bolts. The licensee stated that, even though this plate connection was missing, it should not affect the load path to the anchors. After detailed discussions with the NRC staff, the licensee agreed to look further into this during the audit. The licensee reviewed the IPEEE documentation and noted that this plate connection was not necessary and agreed to update the design drawing to reflect this. This adjusting plate was for alignment and was not needed for this specific configuration since the three skids (generator and engines) used were all placed on a common foundation. During the audit, the licensee did a calculation confirming that the missing bolts in the skid plate connections do not affect the diesel generator load path. The calculated stresses in the diesel generator anchor bolts have little change with or without the presence of the missing anchors. SR-772631 was opened to address this issue.
- 125V Vital Battery Room IV- The NRC staff walked down a previously identified condition in which a masonry block wall had a horizontal crack at the top of the wall.
This crack was approximately 6-feet long and could be seen on both sides of the masonry block wall. The licensee stated that a CAP entry was submitted to address this issue and the wall was deemed adequate to perform its intended function. The plant monitoring program has been updated to track the condition of this wall.
- 480 V Board RM-1A- Shutdown transformer 1A1-A 6900-480-V 175- This transformer was listed as an IPEEE vulnerability and according to the walkdown submittal the bolts attaching the transformer to the wide flange sill were scheduled to be replaced with high strength bolts. The NRC staff walked down this component and noted that the bolts were adequately replaced.
- Auxiliary Building- Equipment ID- SQN PMP-078-0009- The NRC staff walked down this component to visually inspect the white deposits building up between the bolts on the skid. According to the walkdown checklist, this condition was not affecting the anchorage at that time and the minor rust was noted but not deemed adverse. During the audit walkdown, the licensee noted that the white deposit, from leaking of boric acid, was bigger than when the component was initially walked down and decided this condition should be monitored by the boric acid monitoring program per plant procedure.
While performing its own independent area walk-by for this same component, the NRC staff noted several unrestrained barrels and discussed this with the licensee if this could be considered a potential seismic interaction issue. After verifying this condition, the licensee stated that they were in compliance with the plant's procedures since the barrels were restrained by the end of the shift.
AUDIT
SUMMARY
The NRC audit team engaged in various discussions including individual interviews with the licensee and its contractor that led to a significant increase in the level of clarity on the processes used by the licensee when conducting the seismic walkdowns related to Fukushima Recommendation 2.3. Specifically, the NRC staff obtained additional clarification regarding: the background and qualifications and training of individuals who conducted the seismic walkdown activities, participation and roles of the operations staff, scope of the peer review, experience and independence of the peer reviewers, development of the seismic walkdown equipment list 1 and 2, the conduct and reporting of the seismic walkdowns and area walk-bys, and the approach used to disposition potential issues identified during the walkdown activities. By discussing these specific topics in depth with the licensee and reviewing the documentation mentioned above, the team was able to meet the objectives of the audit and gather the information and come to understanding of the licensee's process regarding seismic walkdowns sufficient to address the issues identified in the audit plan.
The licensee performed a self-assessment in preparation to this audit and noted several documentation anomalies similar to the ones previously noted by the NRC staff in their review.
As a result, the licensee committed to submit an updated seismic walkdown report during the audit. This report was submitted on October 4, 2013, and included the NRC staff's observations and provided additional clarity on the licensee's walkdown process. Specifically, the following
updates were included: additional information on the peer review process including a clarification on the role of the lead peer reviewers and the complete and signed checklists; additional information on the training provided to those involved in the seismic walkdown activities; results of the self-assessment including references to new CAP/SRs issued and the updated table with a summary of all the identified PASCs and their respective CAP reference number and origination date.
Entrance Meeting (August 27, 2013)
TVA's Engineering and Licensing management expressed their willingness to support the NRC team during the audit. The NRC staff discussed the audit plan including the scope, topics of discussions and possible path forward with the licensee. The licensee provided a presentation regarding their self-assessment and stated their intention to submit an updated report.
Exit Meeting (August 29, 2013)
The NRC team summarized the activities that were conducted and described the issues that were identified during the three day audit. The licensee was given the opportunity to ask questions. The NRC described its path forward which includes the development of an audit report and a formal staff assessment report. The licensee committed to update their seismic walkdown report within 30 days of the audit. In order to ensure full understanding of the NRC staff's requirements, it was agreed that additional discussions might be conducted via conference calls before this formal submittal.
CONCLUSION The NRC staff gained a better understanding of the methods and procedures used by TVA when conducting seismic walkdown activities at the SON, Units 1 and 2. Specific issues regarding the licensee's seismic report were identified and conveyed. In response, the licensee updated their seismic walkdown reports and these were sent to the NRC on October 4, 2013.
Based on the information gained during the audit and in conjunction with the original and revised submittals by the licensee, the NRC staff believes that they have sufficient information to complete its seismic walkdown assessment of the licensee's response to the 50.54(f) letter.
J Shea If you have any questions, please contact Siva P. Ling am at 301-415-1564 or by e-mail at Siva. Lingam@ nrc.gov Sincerely, IRA/
Siva P. Lingam, Project Manager Projects Licensing Branch 112 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328
Enclosure:
Audit Report cc w/encl: Distribution via Listserv DISTRIBUTION:
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DATE 10/30/13 10/30/13 10/30/13 10/30/13 OFFICE NRO/DSEA: D* DORULPL2-2/BC DORULPL2-2/PM NAME SFianders JQuichocho Slingam DATE 10/18/13 11/12/13 11/12/13 OFFICIAL RECORD COPY