ML12128A426
| ML12128A426 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/26/2012 |
| From: | Gerald Bichof Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 12-312, N1-14-NDE-007, FOIA/PA-2013-0030, FOIA/PA-2013-0139 | |
| Download: ML12128A426 (8) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 April 26, 2012 U.S. Nuclear Regulatory Commission Serial No.12-312 Attention: Document Control Desk NLOS/ETS One White Flint North Docket No.
50-338 11555 Rockville Pike License No.
NPF-4 Rockville, MD 20852-2738 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)
NORTH ANNA POWER STATION UNIT I RELIEF REQUEST NI-14-NDE-007 APPROVAL TO EXTEND THE FOURTH INTERVAL FIRST PERIOD FOR THE REACTOR VESSEL INTERIOR VT-3 VISUAL EXAMINATION (B-N-l)
Pursuant to 10 CFR 50.55a(a)(3)(ii), Dominion is requesting Nuclear Regulatory Commission (NRC) approval to extend the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code Section X1 fourth ten year inservice inspection interval first inspection period for the reactor pressure vessel interior (B-N-i) examination for one refueling cycle at North Anna Power Station (NAPS) Unit 1. The one-cycle extension is being requested on the basis that compliance with the specified requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
North Anna Power Station Unit 1 is currently in the first period of the fourth inspection interval which is scheduled to end on the final day of the spring 2012 refueling outage.
The reactor vessel interior (B-N-i) examination for first period of the fourth interval was intended to be performed during the spring 2012 refueling outage.
However, North Anna Unit 1 is requesting authorization to defer the subject examination until the fall 2013 refueling outage.
Specifically, Dominion is requesting approval of the extension of the inspection period for the Section XI Category B-N-1 reactor pressure vessel interior examination by one refueling cycle beyond the currently scheduled inspection. The basis for this alternative is provided in the attachment to this letter.
Serial No.12-312 Docket No. 50-338 Nl-14-NDE-007 RV Internal Inspections Page 2 of 3 If you have any questions regarding this submittal, please contact Mr. Thomas Shaub at (804) 273-2763.
Very truly yours, G. T. Bischof Site Vice President Commitments made in this letter: None Attachment Alternative Request Nl-14-NDE-007, Request To Extend the Fourth Interval 1st Period Reactor Vessel VT-3 Visual Examination (B-N-i)
Serial No.12-312 Docket No. 50-338 Nl-14-NDE-007 RV Internal Inspections Page 3 of 3 CC.
U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, Georgia 30303-1257 Mr. J. E. Reasor, Jr.
Old Dominion Electric Cooperative Innsbrook Corporate Center 4201 Dominion Blvd.
Suite 300 Glen Allen, Virginia 23060 NRC Senior Resident Inspector North Anna Power Station Dr. V. Sreenivas NRC Project Manager U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 G-9A Rockville, Maryland 20852 Ms. K. R. Cotton NRC Project Manager U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 G-9A Rockville, Maryland 20852 Mr. M. M. Grace Authorized Nuclear Insurance Inspector North Anna Power Station
Serial No.12-312 Docket No. 50-338 Attachment Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(ii)
Hardship or Unusual Difficulty without Compensating Increase in Level of Quality or Safety Virginia Electric and Power Company (Dominion)
North Anna Power Station Unit 1
Serial No.12-312 Docket No. 50-338 Page 1 of 4 Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(ii)
Hardship or Unusual Difficulty without Compensating Increase in Level of Quality or Safety Ni-14-NDE-007 1.0 ASME CODE COMPONENT AFFECTED The affected component is the North Anna Power Station Unit 1 reactor pressure vessel, specifically the following American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel (BPV) Code Section XI examination category and item number covering examination of the reactor vessel (RV). This examination category and item number is from IWB-2500 and Table IWB-2500-1 of the ASME BPV, Code Section XI.
Examination Category Item No.
Description B-N-1 B13.10 Vessel Interior (Throughout this request the above examination category and item number are referred to as "the subject examination" and the ASME BPV Code,Section XI, is referred to as "the Code.")
2.0 APPLICABLE CODE EDITION AND ADDENDA The ASME Boiler and Pressure Vessel Code (ASME Code) of record for the North Anna Power Station Unit 1 fourth inspection interval is the 2004 Edition.
3.0 APPLICABLE CODE REQUIREMENTS IWB-2412, Inspection Program B, requires visual examination of the interior of the reactor pressure vessel identified in Table IWB-2500-1 be performed each inspection period. The North Anna first period of the fourth inspection interval was scheduled to end on conclusion of the current spring 2012 refueling outage.
4.0 REASON FOR REQUEST An alternative is requested from the requirements of IWB-2412, Inspection Program B, which requires a VT-3 visual examination, of the accessible area of the reactor pressure vessel interior made accessible by removal of components during normal refueling outages, to be performed once each inspection period of the interval.
Extension of the Category B-N-1 reactor pressure vessel interior examination by one refueling cycle beyond the currently scheduled inspection period is requested.
ASME Section XI requires that the VT-3 visual examination of the reactor pressure
Serial No.12-312 Docket No. 50-338 Page 2 of 4 Proposed Alternative in Accordance with 10 CFR 50.55a(a) (3) (ii)
Hardship or Unusual Difficulty without Compensating Increase in Level of Quality or Safety vessel interior, Category B-N-i, be performed once every inspection period. The examination involves inspection of the accessible portion of the reactor vessel using either a remote camera on a pole or sub. These accessible areas consist of the vessel flange mating surface and the exposed area of the internals support ledge.
Operations personnel involved with the current refueling activities performed video examinations of the vessel flange, core support plate and former baffles, and no irregularities were observed in this region of the vessel. Subsequent focused reviews of the video by VT-3 qualified personnel in the noted examination areas have also found no evidence of structural degradation or other abnormalities.
Additionally, maintenance personnel, including a VT-3 alternate qualified QC inspector performed direct cleaning and inspections of the Reactor Vessel O-ring sealing surfaces and found no evidence of any conditions within the sealing surface areas that would be considered relevant for the inspection criteria associated with our applicable VT procedure. However, these examinations do not constitute ASME Section XI VT-3 examinations and may not have met the requirements for lighting and resolution verification. Prior to reload of the core during refueling, the lower core plate, the lower core plate forging and vessel bottom, and the top former plate are searched for potential foreign material so that it can be evaluated and removed.
Review of the videos provides additional assurance that there is no structural degradation or conditions that could lead to loss of function.
North Anna Unit 1 recently completed a reactor refueling and the subject examination was intended to be performed during the current refueling outage but was inadvertently missed. North Anna has completed the refueling and is preparing for plant startup. Completing the required reactor vessel interior examination would require a second disassembly and reassembly of the reactor head and upper internals, resulting in additional radiation ALARA concerns and potential hazards to plant personnel without compensating increase in the level of quality or safety.
5.0 PROPOSED ALTERNATIVES AND BASIS FOR USE The planned end of the first period of the fourth inspection interval is the final day of the current spring refueling outage, originally expected prior to April 30, 2012. The subject examination was intended to be performed during the current spring 2012 refueling outage. The proposed inspection date is one refueling cycle beyond the Code-allowed inspection period.
The procedure for this examination inspects the following:
- 1. Structural distortion, displacement of parts to the extent component function may be impaired;
- 2. Loose, missing, cracked or fractured parts, bolting or fasteners;
- 3. Foreign materials or accumulation of corrosion products that could interfere
Serial No.12-312 Docket No. 50-338 Page 3 of 4 Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(ii)
Hardship or Unusual Difficulty without Compensating Increase in Level of Quality or Safety with control rod motion or could result in blockage of coolant flow through the fuel;
- 4. Corrosion or erosion that reduces the nominal section thickness by more than 5%;
- 5. Wear of mating surfaces that may lead to loss of function; or
- 6. Structural degradation of interior attachments such that the original cross-sectional area is reduced more than 5%.
The reactor vessel Category B-N-1 examination item, B13.10, is required to be performed each inspection period, and it was performed satisfactorily each period during the third 10 year inspection interval that ended April 30, 2009. The examination was last performed during the 10-year ISl vessel examinations during the spring 2009 refueling outage, and included the higher level of detail of the 10-year ISI when the core barrel and lower internals are also removed from the core allowing better access to applicable welds and surfaces. No relevant indications were noted during these examinations. Given that the prior examinations were of sufficient quality to identify any significant flaws that would challenge reactor vessel integrity, the proposed alternative of extending the Category B-N-1 examination one cycle provides a reasonable assurance of structural integrity. Additionally, review of industry surveys indicate that these examinations have been performed many times throughout the industry without any reportable findings.
Considering that refueling personnel perform observations each refueling to identify similar relevant conditions as required by the subject B-N-1 examination, and no irregularities were observed other than minor foreign material at the lower core plate and vessel bottom, which was not associated with core component damage and were subsequently removed, delaying this examination one additional operating cycle is considered to have no effect on operational readiness and provides a reasonable assurance of structural integrity without the significant additional dose and hardship associated with completing this examination in the current refueling outage. The subject components have a low likelihood of having significant flaws that can be detected visually.
Therefore, in accordance with 10 CFR 50.55a(a)(3)(ii), this extension of the Category B-N-1 examination is requested on the basis that compliance with the specified requirements would result in hardship or unusual difficulty without compensating increase in the level of quality and safety.
6.0 DURATION OF PROPOSED ALTERNATIVE The proposed alternative is requested to extend the period 1 examination of the reactor vessel interior, Category B-N-i, by one refueling cycle beyond the currently
Serial No.12-312 Docket No. 50-338 Page 4 of 4 Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(ii)
Hardship or Unusual Difficulty without Compensating Increase in Level of Quality or Safety scheduled inspection. Remaining B-N-1 examinations for the 2 nd and 3 rd periods will be performed as required.
7.0 PRECEDENTS A similar request was submitted by Palisades Nuclear Plant, Dated March 31, 2005
[ML050970263].
Arkansas Nuclear One submitted similar requests on April 24, 2006 [TAC No.
MD1395] and February 16, 2009 [ML090480123].