L-PI-03-035, Relief Request to Perform a Visual Examination in Lieu of Volumetric Examination of Reactor Vessel Nozzle Inner Radius Sections Per Code Case N-648-1

Relief Request to Perform a Visual Examination in Lieu of Volumetric Examination of Reactor Vessel Nozzle Inner Radius Sections Per Code Case N-648-1

ML031000516
Person / Time
Site:	Prairie Island
Issue date:	04/03/2003
From:	Solymossy J Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-PI-03-035
Download: ML031000516 (5)

Text

NM C Committed to Nuclear Exce Prairie Island Nuclear Generating Plant Operated by Nuclear Management Company, LLC April 3, 2003 L-PI-03-035 10CFR50.55a(a)(3)(i)

U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT DOCKET NOS. 50-282 AND 50-306 LICENSE NOS. DPR-42 AND DPR-60 TITLE: RELIEF REQUEST TO PERFORM A VISUAL EXAMINATION IN LIEU OF VOLUMETRIC EXAMINATION OF REACTOR VESSEL NOZZLE INNER RADIUS SECTIONS PER CODE CASE N-648-1 The purpose of this letter is to request Nuclear Regulatory Commission (NRC) authorization to perform VT-1 visual examinations in lieu of volumetric examinations of reactor vessel nozzle inner radius sections during the Prairie Island Unit 1 and 2 Third-Ten Year Inservice Inspection Intervals. We are requesting relief pursuant to 10 CFR Part 50, Section 50.55a(a)(3)(i) because the proposed alternative would provide an acceptable level of quality and safety.

The details of the 10 CFR 50.55a(a)(3)(i) request are enclosed in the attached relief request for Prairie Island Unit 1 and Unit 2 (contained in one document). Nuclear Management Company requests approval by September 1, 2003 to support the refueling outage on Unit 2. The proposed alternative was approved for Browns Ferry Unit 2 by NRC on October 7, 2002.

Please contact Jack Leveille (651-388-1121, Ext. 4142) if you have any questions related to this letter.

This letter contains no new commitments and no revisions to existing commitments.

Jo0e hM.S rq~s1y e Vice Preside r rairie Island Nuclear Generating Plant (copies and attachment listed on next page) 1717 Wakonade Drive East

• Welch, Minnesota 55089-9642 Telephone: 651.388.1121

USNRC NUCLEAR MANAGEMENT COMPANY, LLC L-PI-03-035 Page 2 CC Regional Administrator, USNRC, Region IlIl Project Manager, Prairie Island Nuclear Generating Plant, USNRC, NRR NRC Resident Inspector- Prairie Island Nuclear Generating Plant

Attachment:

(one document)

Prairie Island Unit 1 - RELIEF REQUEST NUMBER: 18 (Rev. 0)

Prairie Island Unit 2 - RELIEF REQUEST NUMBER: 18 (Rev. 0) 1717 Wakonade Drive East

• Welch, Minnesota 55089-9642 Telephone: 651.388.1121

Hi ATTACHMENT NUCLEAR MANAGEMENT COMPANY, LLC PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 and 2 DOCKET NOS. 50-282 AND 50-306 LICENSE NOS. DPR-42 AND DPR-60 LETTER NO. L-PI-03-035 Prairie Island Unit 1 - RELIEF REQUEST NUMBER: 18 (Rev. 0)

Prairie Island Unit 2 - RELIEF REQUEST NUMBER: 18 (Rev. 0) 2 pages follow

Nuclear Management Company Inservice Inspection Prairie Island Unit 1 and Unit 2 3 rd Interval Examination Plan Prairie Island Unit 1 - RELIEF REQUEST NUMBER 18: (Rev. 0)

Prairie Island Unit 2 - RELIEF REQUEST NUMBER 18: (Rev. 0)

Use of Code Case N-648-1 SYSTEMICOMPONENT(S) FOR WHICH RELIEF REQUEST WILL BE USED Code Class: Class 1

Reference:

American Society of Mechanical Engineers Code (ASME),

Section XI, 1989 Edition with no Addenda Examination Category: B-D Item Number: B3.100

==

Description:==

Reactor Vessel Nozzle Inner Radius Sections.

CODE REOUIREMENTS:

Table IWB-2500-1, Examination Category B-D, Item Number B3.100, "Reactor Vessel Nozzle Inner Radius Section," requires that a volumetric examination of reactor vessel nozzle inner radius sections be performed.

PROPOSED ALTERNATIVE:

Pursuant to the requirements of 10 CFR 50.55a(a)(3)(i), relief is requested to perform an alternative visual (VT-i) examination consistent with ASME Code Case N-648-1, "Alternative Requirements for Inner Radius Examinations of Class 1 Reactor Vessel Nozzles." In addition, the proposed alternative VT-l examinations will be conducted on the reactor pressure vessel nozzle inner radius sections using an enhanced remote visual (VT-i) examination, capable of a 1-mil wire resolution, in accordance with ASME Section XI, VT-i requirements providing acceptable resolution sensitivity.

BASIS FOR RELIEF:

Nuclear Management Company proposes performing an enhanced VT-1 examination of the Reactor Pressure Vessel (RPV) nozzle inner radius sections in lieu of performing the Code required volumetric examination.

It has been previously demonstrated that even when using improved nondestructive (NDE) volumetric examination technology from the outside surface of a RPV nozzle that the complex geometry of the inner radius section of the nozzle prevents complete ultrasonic coverage. The primary degradation mechanism in RPV nozzles is fatigue cracking, which produces hairline surface indications along the circumference of the nozzle at the inner radius section. Given the 1-mil resolution capability of the enhanced visual examination, it is highly unlikely that such flaws would not be detected using high magnification cameras that can provide full examination coverage of the inner radius surface area. Thus, the proposed visual examination will provide better evidence of the condition of the nozzle.

S Nuclear Management Company Inservice Inspection Prairie Island Unit 1 and Unit 2 3 rd Interval Examination Plan It has been recognized by the ASME Section XI Committee that performing a visual (VT-1) examination of RPV nozzle inner radius sections provides an acceptable level of quality and safety, demonstrated by its approval of ASME Section XI Code Case N-648-1.

IMPLEMENTATION SCHEDULE:

The proposed alternative is requested for the remainder of the 3 rd 10 Year Interval of the Inservice Inspection Program for Prairie Island Unit 1 and Unit 2.

REFERENCE:

Unit Name: BROWNS FERRY 2 Submittal Date(s): 04/23/2002 09/05/2002 Approval Date(s): 10/07/2002