RBG-46493, Supplement to License Amendment Request (LAR) 2006-03, Leakage Rate Testing of Containment Purge Valves
| ML070650311 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 02/28/2007 |
| From: | King R Entergy Operations |
| To: | Document Control Desk, NRC/NRR/ADRO |
| References | |
| RBG-46493 | |
| Download: ML070650311 (6) | |
Text
Entergy Operations, Inc.
River Bend Station 5485 U. S. Highway 61 N St. Francisville, LA 70775 Tel 225 336 6225 En tf gyFax 225 635 5068 rking@entergy.com Rick J. King Director, Nuclear Safety Assurance RBG-46493 February 28, 2007 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
Subject:
River Bend Station Docket No. 50-458 License No. NPF-47 Supplement to License Amendment Request (LAR) 2006-03, "Leakage Rate Testing of Containment Purge Valves"
Reference:
- 1. License Amendment Request (LAR) 2006-03, "Leakage Rate Testing of Containment Purge Valves", dated September 19, 2006
Dear Sir or Madam:
In Reference 1, Entergy Operations Incorporated (Entergy) requested an operating license amendment for River Bend Station (RBS). The proposed license amendment requested deletion of the augmented testing requirement for containment purge supply and exhaust isolation valves with resilient seal materials and allow the surveillance intervals to be set in accordance with the Containment Leakage Rate Testing Program and Regulatory Guide
- 1. 163, Section C 2.
On February 8, 2007, Entergy and members of your staff held a call to discuss questions the NRC staff had concerning the submittal. As a result of the call, questions were determined to require formal response. Entergy's response is contained in Attachment 1.
There are no technical changes proposed. The original no significant hazards consideration included in Reference 1 is not affected by any information contained in the supplemental letter. There are no new commitments contained in this letter.
Although this request is neither exigent nor emergency, your prompt review is requested.
Once approved, the amendment shall be implemented within 60 days.
If you have any questions or require additional information, please contact Mr. Bill Brice at 601-368-5076.
RBG-46493 Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on February 28, 2007.
Sincerely, Rick J. King Director, Nuclear Safety Assurance River Bend Station, Unit 1 RJK/WBB Attachments:
- 1. Response to Additional RAIs for LAR 2006-03 cc:
U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 NRC Senior Resident Inspector P.O. Box 1050 St. Francisville, LA 70775 U. S. Nuclear Regulatory Commission Attn: Mr. N. Kalyanam Attn: Mr. B. Vaidya MS O-7D1 Washington, DC 20555-0001 LA Dept. of Environmental Quality Office of Environmental Compliance Emergency and Radiological Services Div.
P. O. Box 4312 Baton Rouge, LA 70821-4312 To RBG-46493 Response to Request for Additional Information
RBG-46493 Page 1 of 3 TAC MD3025 River Bend 1 09/19/2006 License Amendment Request Leakage Rate Testing of Containment Purge Valves ML062680173 RAI Items:
- 1.
In RBG-46552 Attachment 1, Section 3.0 Second Paragraph it reads "...and are not periodically replaced." Are the containment purge valve resilient seal rings only replaced on an observed condition or leakage test results basis?
Answer: These valves have demonstrated performance that is similar to other valves in the containment leak rate program. The Appendix J leak rate program is designed to detect valve degradation by setting leakage limits low enough to effect repairs before leakage is beyond actual limits. Seat leakage test results are the basis for repair or replacement as is typical for most valves in the program. Note that the current administrative limits were established very conservatively (70 sccm for Z31 and 2,100 sccm for Z33) to provide an early warning of degradation.
Normally a 7,200 sccm admin limit is established for a 36 inch valve (200 sccm /
inch nominal size).
Is there a periodic inspection of the seal rings?
Answer: No, as discussed in Reference 1, Attachment 1, page 2; the improved performance of these types of valves has resulted in the NRC approving reduced leakage testing at several plants when accelerated degradation has not occurred. A review of the RBS leakage history indicates that Appendix J testing intervals would be appropriate. As a result, additional periodic inspections are not proposed.
Are the seal rings only inspected if the valve leakage rate becomes excessive or there is some other reason to suspect they may be deteriorated?
Answer: Yes, normally, the seal rings are inspected / reworked if the valve leakage rate becomes excessive. However, if other work were done to the valves that could expose or damage the seats, inspections would be appropriate.
- 2.
Section 4.0 Second Paragraph reads "The limits below are current administrative limits and may be adjusted in the future." How are these limits related to the leakage limits referred to in River Bend Technical Specification (TS) 3.6.1.3.D "One or more penetration flow paths with one or more primary containment purge valves not within purge valve leakage limits"?
Answer: Exceeding the leakage administrative limits requires the generation of a Condition Report which will receive an operability determination in accordance with our procedure. This is required by the Appendix J program. This evaluation will determine valve operability based on leakage value trend, maintenance history, total Type B&C Leakage margin, and whether the valves will remain operable until the next test or next refueling outage.
- 3.
Section 4.0 Table "Containment Purge Valves Test Results from 1996 to Present" has a data row near the end with the Test Date shown as "12/97". Was "12/96" intended?
RBG-46493 Page 2 of 3 Answer: - Yes, "12/96" was intended. This was a typographical error.
- 4.
Section 4.0 Table:
- a.
Is all valve maintenance that could have affected the valves leakage rate identified in the Table? If any additional maintenance was performed, provide summary of conditions observed and any causes determined for leakage rate changes.
Answer: Work was performed during RF-9 (4/1/00) for HVR-AOV 165 that included replacing the air supply regulator, solenoid valve and rebuilding the booster relay.
The bottom shim was also replaced. This work was performed because the valve failed IST stroke time.
- b. Three rows of data refer to "as left". Are the other entries to be understood as "as found" or "as found" and "as left"? Was the data immediately preceding the "as left" identified data the associated "as found" test results?
Answer: The other entries are "as found" and "as left" because no work was required or performed. The data immediately preceding the "as left" identified data is in fact the associated "as found" test results.
- c. Are all data shown from App J tests or is the within 92 day test performed or dealt with any differently than App J tests? Are the running totals for combined Type B and Type C tests minimum and maximum pathway leakage rates updated with each new set of test results?
Answer: Yes, all tests and results are Appendix J tests.
Answer: Not typically when the leak rate <= the administrative limit, because during a refueling outage, minimum and maximum pathway leak rates are calculated with the administrative limit leak rates entered for penetrations KJB-Z31 / Z33 in lieu of the measured leak rates (see Note in Table 1 below for more information).
However, if the leak rate exceeded the administrative limit, then the running totals would be updated.
- d. Provide estimated if not actual number of times the outlet valves were cycled between tests and the same for the inlet valves. If estimated, the values should be realistic enough to allow for comparison of potential wear and tear during different time intervals. If estimated, describe how estimate was determined.
Answer: This is because the test interval is approximately 90 days. During that period, both outlet and inlet valves are cycled (opened and closed) once every shift for containment purge (90 days x 2 shifts/day x 1 time/shift = 180). This is because the containment is very tight and pressure builds. In addition, during the same period valves are cycled (opened and closed) one time for IST and one time for the LLRT.
- 5.
What is the Combined Type B and Type C leakage rate limit in sccm? What have the "as found" and "as left" Combined Type B and Type C leakage rate totals been over the past 10 years?
Answer: The Combined Type B and Type C leakage rate limit in sccm is 83,061
RBG-46493 Page 3 of 3 sccm (0.6 L.). To determine what the "as found" and "as left" Combined Type B and Type C leakage rate totals have been over the past 10 years, see Table 1 and Table 2 below. Containment leakage margin can be found by subtracting the "as left" Type B&C leak rate from the TS limit which is also shown in the tables. The leakage margin at the startup following the last outage (RF-1 3) was 64,080 sccm (using max path for "as left" leak rate, per App. J, during an outage).
- 6.
Provide any available leakage rate test data obtained subsequent to the 09/19/2006 LAR submittal.
Answer: See Table 3 below. In addition, the current containment leakage margin is 76,827 sccm.
Table 1. Total Type B&C Leak Rates Past 10 years (when leak rates were within admin limit)
Note: From RF08 to present, Total Type B&C Leak Rates during refueling outages were calculated with 70 sccm and 2,100 sccm (admin limits) for Z31 and Z33, respectively. This is conservative. As a result, Total Type B&C Leak Rates are not required to be updated following LLRTs if the measured leak rates of Z31 and Z33 are within the admin limits.
Refuel Outage #
"As Found" in sccm "As Left" in sccm TS limit in sccm (Date)
(Min Path)
(Max Path Prior to for AF and AL Startup)
(0.6 La)
RF13 (May 06) 7,363 18,981 83,061 RF12 (Nov 04) 7,574 17,842 83,061 RF1 1 (Apr 03) 7,050 21,946 83,061 RF10 (Oct 01) 7,662 12,392 66,449 RF09 (Apr 00) 11,389 10,999 66,449 RF08 (Jun 99) 4,780 10,598 66,449 RF07 (Oct 97) 9,353 11,503 66,449 RF06 (Feb 96) 7,707 15,052 66,449 Table 2. Total Type B&C Leak Rates Past 10 years (when leak rate exceeded admin limit)
Date "As Found" in sccm "As Left" in sccm TS limit in sccm (Min Path)
(Min Path is used during for AF and AL plant operation)
(0.6 La) 12/20/06 6,234 6,234 83,061 09/20/06 4,974 4,974 83,061 03/31/06 5,484 5,484 83,061 01/08/98 & 01/09/98 not avail 9,424 66,449 Table 3. New Test Data KJB-Z31 Penetration KJB-Z33 Penetration Test Date Leakage Limit 70 sccm Leakage Limit 2,100 sccm 12/20/06 15 (see note) 3,700 9/20/06 5
(see note) 2,440 Note: Leakage exceeded admin limit and was accepted based on 1) Total Containment Type B&C Leak Rate was well below TS limit. 2) The seal rings were new and known not to be degraded, and 3) The leakage trend was linear and would not have impacted overall leakage limit prior to the next test.