North Anna – Dominion Again Quotes EPRI Reports in Restart Documents

Author: No Comments Share:

U.S. Nuclear Regulatory Commission Serial No.: 11-544B Attention: Document Control Desk NL&OS/ETS R1 Washington, DC 20555 Docket Nos.: 50-338/339 License Nos.: NPF-4/7
VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION) NORTH ANNA POWER STATION UNITS 1 AND 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING THE EARTHQUAKE ON AUGUST 23, 2011 AND RESTART READINESS DETERMINATION PLAN

By letter dated September 14, 2011, the NRC requested additional information (RAI) regarding the August 23, 2011 Central Virginia earthquake. By letters dated September 27, 2011 (11-544), and October 3, 2011 (Serial No. 11-544A), Dominion responded to several of the questions provided by the NRC technical review branches. However, the response to one of the RAI questions was being developed and was therefore not included in the previous responses. As a result, Dominion is providing a response to the remaining question, Fuels Question 1, in Attachment 1 to this letter.

Attachment 1 contains information proprietary to AREVA, and is supported by an AREVA Application for Withholding Proprietary Information for Public Disclosure and the accompanying Affidavit signed by AREVA, the owner of the information, and is provided in Attachment 3. The affidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b)(4) of 10 CFR 2.390 of the Commission’s regulations.

Accordingly, it is respectfully requested that the information, which is proprietary to AREVA NP, be withheld from public disclosure in accordance with 10 CFR 2.390. Correspondence with respect to the copyright or proprietary aspects of Section 4, Table 1, entitled “Advanced Mark-BW Fuel Design Margin (seismic and Normal Operating),” in Attachment 1 of this letter or the supporting AREVA NP affidavit should be addressed to Ms. Gayle F. Elliott, Manager, Product Licensing, AREVA NP, Inc., 3315 Old Forest Road, P.O. Box 10935, Lynchburg, VA 24506-0935. A redacted (non¬proprietary) version of Attachment 1 has been included as Attachment 2 for public disclosure.

Dominion provided responses to individual NRC questions contained in the NRC letter dated September 14, 2011. Specifically, Dominion

2. FANP Topical Report, BAW-10239(P)(A), Revision 0 (Reference 2), provides an evaluation of the Advanced Mark-BW fuel assembly in a sample reactor against the criteria defined in the Section 4.2 of the Standard Review Plan (SRP). Section 5.3.4 of the topical report discusses fuel assembly structural damage from external forces, such as the operating basis earthquake (OBE), the safe shutdown earthquake (SSE), as well as SSE + loss-of-coolant-accident (LOCA) loads. The evaluation of faulted conditions also addresses both horizontal (LOCA and seismic) and vertical LOCA effects. Based on the availability of information to date from VEPCO’s presentation and the Advanced Mark-BW fuel mechanical design report, the Nuclear Regulatory Commission (NRC) staff is unable to verify the operability condition for the core internals, specifically for the fuel assemblies(grids,fuel rods, guide tubes) and control rods.

c) Please provide a comprehensive strategy and qualifying criteria for determining the operability of these components.

d) Provide a comparison of the predicted design basis loads (e.g., local acceleration) on the core internals and fuel assemblies against the predicted loads derived from the measured ground motion data during the seismic event. In addition, compare these predicted loads against the measured yielding load and deflection from the fuel assembly grid crush testing.

c) Describe all sources of technical information considered in determining the operability and integrity of the fuel, including involvement of the fuel vendors

Dominion Response to Part a)

Fuel Assemblies
The strategy for determining the operability of the fuel assemblies and insert components was to thoroughly inspect a sampling of fuel assemblies and insert components that were in the new fuel storage area, in the spent fuel pool, and in the Unit 2 core. Details of the fuel assembly and insert component inspections performed and their qualifying criteria are provided in the attachment to Dominion’s letter dated September 27, 2011 (Serial No. 11-544 -Fuels RAI No. 2). Rod cluster control assembly (RCCA) drag testing was also performed in the spent fuel pool following the Unit 2 core offload to confirm the integrity of the fuel assembly guide tubes. The details of the RCCA drag testing and the qualifying criteria are provided in the attachment to Dominion’s letter dated October 3, 2011 (Serial No. 11-544A -Fuels RAI No. 2). No indications of damage to any fuel or insert components were observed during the fuel assembly inspections and RCCA drag testing.

The fuel assemblies and insert components in North Anna Unit 1 are of the same design as the Unit 2 fuel and insert components that were inspected. Further, Unit 2 is in close proximity to Unit 1 and is oriented 180 degrees from the Unit 1 core. Due to the symmetric characteristics of the core and fuel assemblies, directionally dependent forces or motions would impact the Unit 1 and Unit 2 cores in the same manner. Therefore, the effect of the seismic loads on the Unit 1 fuel and inserts would be similar to the effect on the Unit 2 fuel and inserts. No damage to the Unit 2 fuel or inserts was identified by the visual inspections and tests that were performed, so it is concluded that the North Anna 1 fuel and inserts were similarly not damaged as a result of the August 23, 2011 earthquake and they will continue to perform their design function.
In addition to the inspections mentioned above, the loads experienced by the fuel assemblies in the Units 1 and 2 cores during the August 23, 2011 earthquake were modeled by AREVA. The in-core fuel assembly stresses (generated from the August 23, 2011 earthquake loads) were compared to an operability limit (OBE) for each fuel assembly component listed in Table 7.3-2 of the North Anna Advanced Mark-BW Design Report (BAW-2414P, Revision 7). The calculation results indicate that none of the fuel assembly components experienced plastic deformation during the August 23, 2011 earthquake.

Rod Cluster ControlAssemblies (RCCAs)
The strategy for determining the operability of the RCCAs was to perform visual inspections and functional testing. To confirm the RCCA hubs and associated welds were not damaged during the August 23, 2011 earthquake, inspections of the Unit 2 RCCAs were performed as described in the attachment to Dominion’s letter dated September 27, 2011 (Serial No. 11-544 -Fuels RAI No. 2). In addition, RCCA drag loads using fuel assemblies in the Unit 2 core at the time of the August 23, 2011 earthquake were measured in the spent fuel pool to confirm that there was no distortion of the RCCA rodlets or the fuel assembly guide tubes, and that the RCCAs could still travel freely within the fuel assembly guide tubes. The details of the RCCA drag testing and the qualifying criteria are provided in the attachment to Dominion’s letter dated October 3, 2011 (Serial No. 11-544A -Fuels RAI No. 2). No indications of damage to the fuel or RCCAs were identified during the RCCA drag load measurements performed in the spent fuel pool.
Per the normal refueling outage scope, Unit 2 RCCA drag load measurements were performed after the core was loaded and the RCCAs latched to their respective control rod drive-shaft. These drag load measurements are performed to verify the RCCAs are latched properly and move freely in the fuel assembly guide tubes and upper internals guide structure. The post-latch drag load values were compared to pre-existing AREVA criteria and determined to be acceptable.

The RCCAs in North Anna Unit 1 are of the same design as the Unit 2 RCCAs that were inspected, and are constrained in the core in the same manner as the Unit 2 RCCAs. Further, Unit 2 is in close proximity to Unit 1 and is oriented 180 degrees from the Unit 1 core. Due to the symmetric characteristics of the core and RCCAs, directionally dependent forces or motions would impact the Unit 1 and Unit 2 cores in the same manner. The effect of the seismic, loads on the Unit 1 RCCAs would therefore be similar to the effect on the Unit 2 RCCAs. No damage to the Unit 2 RCCAs was identified by the visual inspections that were performed, and the RCCA drag load measurements were acceptable. It is therefore concluded that the North Anna Unit 1 RCCAs were similarly not damaged as a result of the August 23, 2011 earthquake and they will continue to perform their design function.
As discussed in the attachment to Dominion’s letter dated September 27, 2011 (Serial No. 11-544 -Fuels RAI No. 4), the control rod drive system will also undergo surveillance testing to verify Technical Specification compliance. RCCA drop time measurements of the Unit 1 and Unit 2 RCCAs will be performed in accordance with station procedures (full RCS flow conditions) as confirmation of the full functionality of the RCCAs and will verify compliance with Technical Specification Surveillance Requirement 3.1.4.3. This surveillance verifies that the RCCAs drop into the core in less than or equal to 2.7 seconds. Units 1 and 2 will also perform control rod operability testing as part of startup to confirm compliance with Technical Specification Surveillance Requirement 3.1.4.2, which verifies rod freedom of movement. The performance of these surveillance tests will be used to further validate the conclusion made from inspections and surveillance tests already performed, which is that the RCCAs were not damaged as a result of the August 23, 2011 earthquake and they will continue to perform their design function.

Reactor Vessel Internals (RVIs)
The strategy for determining the operability of the reactor vessel internals was to perform a margin assessment of the key interface components and confirmatory video inspections. The details of the margin assessment were provided in Enclosure 3 of Dominion’s letter dated September 17, 2011 (Serial No. 11-520). A list of the reactor vessel internals inspections was provided in the attachment to Dominion’s letter dated October 3, 2011 (Serial No. 11-544A -Fuels RAI No. 8). Further details of the inspections were provided in the attachment to Dominion’s letter dated October 10, 2011 (Serial No. 11-566A -Vessel and Internals RAI No. 2). The margin assessment and inspections support the conclusion that the August 23, 2011 earthquake resulted in no physical or functional damage to the RVIs, and that the RVIs remain capable of performing their design bases functions.

FuelAssemblies
In order to evaluate the impact of the August 23, 2011 earthquake on the AREVA Advanced Mark-BW fuel assemblies in the North Anna cores, Dominion provided Westinghouse (the NSSS vendor) with the recorded time-history accelerations from the August 23, 2011 earthquake. Westinghouse used these accelerations to generate core plate motions, which were provided to AREVA. These core plate motions were then used by AREVA to calculate the loads and stresses on the fuel assembly components listed in Table 7.3-2 of the North Anna Advanced Mark-BW Design Report (BAW-2414P, Revision 7). AREVA’s calculations show that the fuel assembly component stresses/loads were within the allowable limits.

Based on AREVA’s calculations, the Advanced Mark-BW fuel assembly components, and therefore the fuel assembly itself, did not yield or permanently deform as a result of the August 23, 2011 earthquake. This analytical result is consistent with the results of the fuel inspections described in the attachment to Dominion’s letter dated September 27, 2011 (Serial No. 11-544 -Fuels RAI No. 2). Therefore, it is concluded that the August 23, 2011 earthquake did not cause any component in the Advanced Mark-BW fuel assembly to yield and that the fuel assemblies in North Anna Units 1 and 2 cores maintain their ability to perform their design functions.

The evaluation of the combined Design Basis Earthquake (DBE) plus LOCA core plate motions was compared to the evaluation of the combined August 23, 2011 earthquake plus LOCA core plate motions. AREVA concluded that the evaluation of the current DBE plus LOCA core plate motions bounds the evaluation of the August 23, 2011 earthquake plus LOCA core plate motions. DBE plus LOCA is bounding due to the maximum LOCA load occurring primarily in the East/West direction and the August 23, 2011 earthquake occurring primarily in the North/South direction.

Although the Westinghouse RFA-2 fuel product has not yet been introduced at North Anna, Westinghouse also evaluated the RFA-2 fuel design with the August 23, 2011 core plate motions. Their calculations concluded that the RFA-2 fuel design would remain within the yield limits for the mid grid, IFM grid, fuel rod, and guide tubes, if RFA¬2 fuel had ‘been in the North Anna cores during the August 23, 2011 earthquake. Therefore, the RFA-2 fuel assembly’s structural integrity is maintained for an earthquake similar to the August 23, 2011 earthquake. Westinghouse also concluded that the combined DBE plus LOCA core plate motions bound the August 23, 2011 earthquake plus LOCA core plate motions for the RFA-2 fuel product due to the maximum LOCA load being primarily in the East/West direction and the August 23, 2011 earthquake being primarily in the North/South direction.

ReactorVessel Internals
As stated in Enclosure 2 of the submittal dated September 17, 2011 (Serial No. 11-520), evidence of the inspections is consistent with Damage Intensity 0 on the EPRI seismic damage scale. No specific inspections of reactor internals or associated components are specified in EPRI NP-6695 for Intensity 0 earthquakes. Since the earthquake did not produce any significant physical or functional damage to safety related plant SSCs and only limited damage to non-safety related, non-seismically designed plant SSCs, there is a reasonable assurance that there is no physical or functional damage to the reactor vessel internals (RVIs), and that the RVIs remain functional and capable of performing their design functions. Additional evaluations of the RVI design margins, as discussed in Enclosure 3 of Dominion’s letter dated September 17, 2011 (Serial No. 11¬520), and the attachment to the October 3, 2011 letter (Serial No. 11-566 -Vessel and Internals RAI No. 1), have been performed based on existing design analyses of the structural integrity of the RVIs. These evaluations, in addition to providing the reasonable assurance of continued functionality described above, support the conclusion that the earthquake resulted in no physical or functional damage to the RVIs, and that the RVIs remain capable of performing their design bases functions.

Although not required by EPRI NP-6695, Dominion, in collaboration with Westinghouse (the NSSS vendor), identified certain inspections of the RVIs to supplement the above conclusion that the RVIs remain capable of performing their design bases functions. These inspections are listed in the attachment to Dominion’s letter dated October 3, 2011 (Serial No. 11-544A -Fuels RAI No. 8). Further details of the RVIs inspections were provided in the attachment to Dominion’s letter dated October 10, 2011 (Serial No. 11-566A -Vessel and Internals RAI No. 2). The results of the RVI inspections showed no anomalous conditions caused by the August 23, 2011 earthquake.

Dominion Response to Part c)

The following is a list of sources used to determine the operability of the fuel.
1. EPRI Report NP-6695, “Guidelines for Nuclear Plant Response to an Earthquake,” December 1989.
This document only mentions fuel and control rods briefly. Results of physical inspections of the plant indicate the seismic event damage is consistent with Intensity 0 on the EPRI seismic damage scale. NP-6695 describes how prescribed inspections and tests are keyed to the severity of the earthquake. No specific inspections of fuel or associated components are specified in NP-6695 for Intensity 0 earthquakes.

2. EPRI Report No. 1016317, “EPRI Independent Peer Review of the TEPCO Seismic Walkdown and Evaluation of the Kashiwazaki-Kariwa Nuclear Power Plants,” January 2008.
This document indicates that during the seismic walkdown following the Kashiwazaki-Kariwa earthquake, TEPCO reported no evidence of any fuel damage. This was confirmed by inspection on a sampling of fuel elements. EPRI recommended that one or more of the reactor vessels be opened for examination of the fuel and internals prior to determination of the plant readiness for restart.
This report was used as the basis for inspecting a sampling, rather than all, of the fuel assemblies. The EPRI panel recommendation to TEPCO is also consistent with Dominion’s use of the Unit 2 fuel examinations to determine the condition of the fuel in Unit 1 (without explicit examination of the fuel in both units).
3. IAEA Safety Guide 66, “Earthquake Preparedness and Response for Nuclear Power Plants,” 2011.

This report does not specifically recommend disassembly of the reactor and inspection of the fuel unless there is significant damage to structures, systems, and components (SSCs) important to safety. Since the earthquake did not produce any significant physical or functional damage to safety related plant SSCs and only limited damage to non-safety related, non-seismically designed plant SSCs, Dominion’s approach of inspecting a sample of components goes beyond the recommended guidance in this report.

4. AREVA Report BAW-2414P, “North Anna Design Report for Units 1 and 2,” April 2007. 2 This document was reviewed to determine the design limitations and current analysis of record for the AREVA Advanced Mark-BW fuel.

5. AREVA AREVA staff members were consulted in generating the list of fuel assembly and insert component inspections necessary to show operability. AREVA provided Dominion with recommendations on the scope of the fuel inspections, and was contracted to assist in the fuel and component inspections. Lastly, AREVA was contracted to perform a fuel assembly stress analysis based on time-histories of the August 23, 2011 earthquake.

6. Westinghouse
Westinghouse was contacted to determine if any RCCA inspections were recommended. Westinghouse personnel were contracted to support the RCCA drag testing, the generation of reactor vessel internals inspections, and the margin assessment performed for key interface components. In addition, Westinghouse was contracted to generate the core plate motions discussed above in response to RAI 1.b.

AFFIDAVIT COMMONWEALTH OF VIRGINIA ) ) ss. CITY OF LYNCHBURG
1. My name is Gayle F. Elliott. I am Manager, Product Licensing, for AREVA NP Inc. (AREVA NP) and as such I am authorized to execute this Affidavit.
2. I am familiar with the criteria applied by AREVA NP to determine whether certain AREVA NP information is proprietary. I am familiar with the policies established by AREVA NP to ensure the proper application of these criteria.
3. I am familiar with the AREVA NP information contained in the attachment to Dominion Letter, Serial No. 11-544B, Section 4.0, Table 1 entitled “Advanced Mark-BW Fuel Design Margin (Seismic and Normal Operations),” and referred to herein as “Document.” Information contained in this Document has been classified by AREVA NP as proprietary in accordance with the policies established by AREVA NP for the control and protection of proprietary and confidential information.
4. This Document contains information of a proprietary and confidential nature and is ofIthe type customarily held in confidence by AREVA NP and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.
5. This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR 2.390. The information for which withholding from disclosure is
requested qualifies under 10 CFR 2.390(a)(4) “Trade secrets and commercial or financial information.” ,6’ The following criteria are customarily applied by AREVA NP to determine whether information should be classified as proprietary:
(a) The information reveals details of AREVA NP’s research and development plans and programs or their results.
(b) Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.
(c) The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for AREVA NP.
(d) The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for AREVA NP in product optimization or marketability.
(e) The information is vital to a competitive advantage held by AREVA NP, would be helpful to competitors to AREVA NP, and would likely cause substantial harm to the competitive position of AREVA NP.

The information in this Document is considered proprietary for the reasons set forth in paragraphs 6(b) and 6(c) above.
1. In accordance with AREVA NP’s policies governing the protection and control of information, proprietary information contained in this Document has been made available, on a limited basis, to others outside AREVA NP only as required and under suitable agreement providing for nondisclosure and limited use of the information.
2. AREVA NP policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.
9. The foregoing statements are true and correct to the best of my knowledge,
information, and belief.

Previous Article

March 11th, 2011 – Temperature in Reactor 1 Fuel Rods Up 50% Above Normal Levels

Next Article

Japanese Government Reserves More For Compensation Then Decontamination