ML20138C016
| ML20138C016 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 03/28/1986 |
| From: | Murphy W VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Muller D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0619, RTR-NUREG-619 NVY-86-29, NUDOCS 8604020102 | |
| Download: ML20138C016 (3) | |
Text
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ERMONT YANKEE NUCLEAR POWE'R CORPORATION NVY 86-29 RD 5. Box 169 Ferry Road Brattleboro, VT 05301 y,go ENGINEERING OFFICE y
1671 WORCESTER ROAD FR AMINGHAM, MASSACHUSETTS 01701 T Ett. PHONE 617 872 0 00 March 28, 1986 United States Nuclear Regulatory Commission
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Washington, DC 20555 Attention:
Office of Nuclear Reactor Regulation Nr. Daniel R. Nuller, Director BWR Project Directorate No. 2 Division of BWR Licensing
References:
(a)
License No. DPR-28 (Docket No. 50-271)
(b) Letter, USNRC.to WNPC, dated November 13, 1980, "NUREG-0619, BWR Feedwater Nozzle and Control Rod Drive Return Like Cracking" (c) Letter, USNRC to WNPC, NW 84-144, dated June 27, 1984 (d)
Letter, WNPC to USNRC, FW 81-141, dated September 25, 1981 (e) Letter, WNPC to USNRC, FW 82-3, dated January 15, 1982 (f) Letter, WNPC to USN'tC, FW 82-105, dated September 21, 1982 (g) Letter, WNPC to USNRC, FW 83-46, dated Nay 26, 1983 (h)
Letter, USNRC to WNPC, NW 83-128, dated June 1,1983, Inspection Report No. 83-02 (i) Letter, USNRC to WNPC, dated August 1,1984, Inspection Report No. 84-13
Subject:
Request for Revision of Routine Inspection Interval Guidance Provided by NUREG-0619, Based on Accumulated Plant-Specific Experience
Dear Sir:
Reference (c) forwarded the NRC's Safety Evaluation Report regarding l
Vermont Yenkee's compliance with the guidance of NUREG-0619. The Safety Evaluation concluded, "... that an adequate margin of safety against feedwater nozzle crack growth exists. However, the licensee should safeguard against any increase of the leakage flow in the future. -The licensee should continue to perform the routine inspections of the feedwater nozzles and spargers in accordance with the intervals specified in Table 2 of NUREG-0619."- The routine inspection intervals in Table 2 of NUREG-0619 for plants having interference-fit feedwater spargers with stainless steel clad feedwater nozzles (Vermont Yankee's configuration) states that ultrasonic examinations (UT) of the feedwater nozzles should be performed at each refueling outage.
In addition, such plants should perform dye penetrant (PT) examinations of the feedwater nozzle blend radii no later than the second refueling cycle after the previous PT.
8604020102 860329 PDR ADOCK 05000271 8
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- VERMONT YANKEE NUCLEAR POWER COHFORATION U.S. Nuclear Regulatory Commission March 28, 1986 Page 2 NUREG-0619 and its attachments repeatedly state that the required in-vessel PT is not a desirable long-term activity due to the associated
. radiation exposure. Licensees were encouraged to develop and implement improved ultrasonic inspection techniques and on-line leakage monitoring systems as alternatives to PT examinations. Relative to inspection intervals, NUREG-0619 specifically states in pertinent part that, "The inspection intervals apply to all plants of each configuration but may be revised as experience accumulates."
The purpose of this letter is to notify you of Vermont Yankee's determination that, based on our qualified UT procedures, leakage monitoring experience and PT inspection history, further PT inspection of-the feedwater nozzles at Vermont Yankee with the accompanying personnel exposure is no longer warranted. Specifically, the basis for our determination includes the following:
o Interference fit spargers were installed in 1976.
o PT examinations in 1977, 1979, and 1981 (results presented in-References (d) and (e)) showed that no reportable indications had developed in the feedwater nozzle blend radii following the installation of the new spargers, demonstrating effective resolution of previous bypass leakage concerns, o
During the 1981 outage, an on-line leakage monitoring system was installed to provide early indication of any increase in bypass leakage around the interference fit sparger.
Experience with this system since installation has shown a stable trend in temperature monitoring demonstrating that the sparger fit is unchanged.
o During the 1983 refueling outage, Vermont Yankee implemented a UT examination procedure which was qualified on a full size feedwater j
nozzle mockup and witnessed by the NRC. With NRC's concurrence, no
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PT was required in 1983 based on the use of the approved UT l
procedure. NRC review of the UT implementation (procedures, mockup, certification, and data) is documented in References (h) and (i).
I Since 1981, continual monitoring of bypass leakage at Verscnt Yankee has
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shown no trend toward increased Dypass leakage, which is necessary to initiate l
cracking. Applications of approved state-of-the-art UT procedures in 1983,
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1984, and again during this outage resulted in no reportable indications.
Based on nine years of operation with no indication of any degradation in the
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interference fit spargers, Vermont Yankee has concluded that any additional personnel exposure expended to perform feedwater nozzle PT is unwarranted.
Because records of past PT examinations show that approximately 15 man-rem of
VERMONT YANKEE NUCLEAlt POWEit CORPOllATION U.S. Nuclear Regulatory Commission March 26, 1986 Page 3 exposure are incurred during the examination procedure, continuing this unnecessary inspection is not in concert with the principles of ALARA. The demonstrated effectiveness of our continuing on-line Leakage Monitoring System Program and UT procedures in providing early indications of potential problems provides more than adequate assurance that any degradation in the presently installed spargers would be detected and corrected in a timely fashion.
Based on the above, it is Vermant Yankee's position that the routine inspection intervals for feedwater rozzle PT examinations are no longer warranted at Vermont Yankee. Theref,)re, we request your concurrence that feedwater nozzle PT examinations are'not necessary for this outage and should be discontinued at Vermont Yankee based on the accumulated plant-specific experience and the adequacy of our continuing UT examination and Leakage Detection System Program.
In accordance with the guidance of Table 2 of NUREG-0619, Vermont Yankee will continue the annual UT examination, the biannual visual inspection of the spargers, and the continual monitoring of bypass leakage. Additionally, should future UT examinations show reportable indications, a PT inspection will be performed to quantify those indications.
In accordance with the provisions of 10CFR170.12, an application fee of
$150.00 is enclosed. We are willing to meet with you and your staff regarding this request at your earliest possible convenience.
Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION W
$m Warren P. Murphy Vice President an n ger of Operations RWC/no Enclosure i