ML20207L923

Requests Permanent Rev of Routine Insp Interval Guidance Provided by NUREG-0619 for Liquid Penetrant Insp of Feedwater Nozzle Blend Radius.Rev 0 to 83A0764 Re 10-yr Insp & Rev 2 to Procedure 80A7616 Re Ultrasonic Exam Encl

ML20207L923
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	01/05/1987
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	Muller D Office of Nuclear Reactor Regulation
Shared Package
ML20207L928	List: ML20207L923 ML20207L973 ML20207L991
References
RTR-NUREG-0619, RTR-NUREG-619 FVY-87-02, FVY-87-2, NUDOCS 8701130038
Download: ML20207L923 (3)

Text

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VERMONT YANKEE NUCLEAR POWER CORPORATION FVY 87-02

. RD 5 Box 169. Ferry Road, Brattleboro, VT 05301 , , , , , ,

g hjgf ENGINEERING OFFICE 1671 WORCESTER ROAD

• FRAMINGHAM. MASSACHUSETTS 01701

• TELEPHONE 617-472-6100 January 5, 1987 United States Nuclear Regulatory Commission Washington, DC 20555 Attention: Office of Nuclear Reactor Regulation Mr. Daniel R. Muller, Director BWR Project Directorate No. 2 Division of BWR Licensing

References:

(a) License No. DPR-28 (Docket No. 50-271)

(b) Letter, VYNPC to USNRC, FVY 86-29, dated March 28, 1086 (c) Letter, USNRC to VYNPC, NVY 86-73, dated April 18, 1986

Subject:

Request for Permanent Revision of Routine Inspection Interval Guidance Provided by NUREG-0619 for Feedwater Nozzle PT Examinations

Dear Sir:

By letter dated March 28, 1986 (Reference (b)), Vermont Yankee requested a revision to the routine inspection interval guidance contained in Table 2 of NUREG-0619. "BWR Feedwater Nozzle and Control Rod Return Line Nozzle Cracking," for liquid penetrant inspection of the nozzle blend radius. On April 18, 1986, (Reference (c)), the NRC staff approved omitting the liquid penetrant inspection of the feedwater nozzle bland radius for the 1985/1986 refueling cycle. At that time, your staff stated that Vermont Yankee's request to eliminate this inspection on a permanent basis would be acted on separately.

The purpose of this letter is to reiterate vermont Yankee's prior request to permanently eliminate the liquid penetrant inspection of the feedwater nozzle blend radius on the basis of accumulated plant-specific experience, the adequacy of our continuing UT examination and Leakage Detection System Program as documented in Reference (b), and maintaining radiation exposures As Low As Reasonably Achievable (ALARA). In accordance with the guidance of Table 2 of NUREG-0619, Vermont Yankee will continue the once-per-cycle UT examination and the continuallmon_itoring of bypass leakage. As previously committed in Reference (b), should future UT examinations show reportable indications, a PT inspection will be performed to quantify those indications. In addition, Vermont Yankee will continue periodic visual inspections of the spargers in accordance with ASME Section XI (Categories B-N-1 and B-N-2).

/

8701130038 870105 Ok PDR ADOCK 05000271 l G PDR ' \

United States Nuclear Regulatory Commission January 5, 1987 Attention: Mr. Daniel R. Nuller, Director Page 2 To further support our request, a summary of the Vermont Yankee feedwater nozzle UT examination technique and the results of the 1985/1986 outage UT examination of the feedwater nozzle blend radius are provided as Enclosures 1 and 2, respectively. The 1985/1986 outage UT examination results fully support the 1977, 1979, and 1981 PT examination results which showed that no reportable indications had developed in the feedwater nozzle blend radli following the installation of the new spargers, demonstrating effective resolution of previous bypass leakage conceras.

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".

Accordingly, Vermont Yankee reiterates its prior request for NRC staff concurrence that the routine inspection intervals for feedwater nozzle PT examinations are no longer warranted at Vermont Yankee. In order to fully address this matter in our planning efforts for the 1987 refueling cycle (approximately August 1987), we request your timely attention to this request. Should you have any questions or require additional information in this regard, please contact this office.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION

/k/ou. / 1 Warren . Murp Vice President an ..anager of Operations I HWC/kg i

Enclosures l

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ENCLOSURE 1 Vermont Yankee Feedwater Nozzle UT Examination Technique Summary

Background

The Vermont Yankee Feedwater Nozzle inner radius ultrasonic examination technique is comprised of two separate examination zones, examined using three separate approach angles, both in the clockwise and counter-clockwise direction. The technique was originally developed and used in 1983 using two approach angles. The 1983 technique was developed using the Nine-Mile Point Unit 1 Feedwater Nozzle Mockup. Adjustments to the technique were then made to account for the differences in geometry between the Vermont Yankee vessel and the Nine-Mile Point Mockup.

In 1984, Vermont obtained a plant-specific mockup containing machined in

" flaws." The 1983 technique was demonstrated on the VY mockup, and an additional scan for defects located deep in the nozzle bore region was implemented. The technique, procedure, and examiners were demonstrated as capable of detecting and discriminating all flaws in the 1984 test set with no false flaws called.

Similarly, the 1985 examination was conducted using the same procedure.

The qualification was again performed, this time with a different test set.

-All flaws were detected and discriminated with no false flaws called.

Ultrasonic examinations of all four nozzles have been completed at each of the last three refueling outages. No defects have been identified during these

! examinations.

Technique The Examination Zone 1 is the actual radiused section at the bore to vessel transition. Zone 1 is examined using a nominal 1.0 MHz transducer, one inch in diameter refracted to a nominal 700 shear wave. Scanning is conducted both in the clockwise and counter-clockwise directions so as to intersect the 5 nozzle inner radius area at a tangent to the bore circumference.

Zone 2 coverage is achieved in two stages from the nozzle boss outside diameter. Using a 1/2" X 1", 2.25 MHz (NOM.) transducer, a refracted shear is generated at 190 to the bore radial line and 330 toward the inner radius.

Refracted shear waves interact with flaw indications at approximately 450 with respect to the bore-flaw intersection. This compound angle achieves Zone 2 coverage of the nozzle bore region as it approaches the inner radius. The remainder of Zone 2 is covered from the same nozzle OD surface using a 190 refracted shear, both clockwise and counter-clockwise.

The total of Zones 1 and 2 coverage is the nozzle inner radius and approximately 12 inches of the bore region. ,

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