ML20238E912
| ML20238E912 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 08/31/1998 |
| From: | Swailes J NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20238E914 | List: |
| References | |
| RTR-REGGD-01.150, RTR-REGGD-1.150 NLS980133, TAC-M93724, NUDOCS 9809020289 | |
| Download: ML20238E912 (5) | |
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N Nebraska Public Power District Nebraska's Energy Leader NLS980133 August 31,1998 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Gentlemen:
Subject:
Inspection of Reactor Vessel Shell Welds Cooper Nuclear Station, NRC Docket 50-298, DPR-46
Reference:
- 1. Letter (No. NLS950111) to USNRC Document Control Desk from John H.
Mueller (NPPD) dated May 5,1995, " Inservice Inspection Interval Revision per 10 CFR 50.55a" The purpose of this letter is to request approval of the attached relief request as an alternative to the requirements of the ASME Code Section XI 1989 Edition in accordance with 10CFR50.55a(a)(3). During the recent Reactor Pressure Vessel (RPV) Inspection Conference, the NRC stated their expectation that the use of Performance Demonstration Initiative (PDI) procedures for the vessel shell weld inspection should be submitted as a request for reliefin lieu of using IWA-2240. In Reference 1, the Nebraska Public Power District (The District) conmitted to perform the required augmented examinations during the Fall 1998 Refueling Outage. The General Electric (PDI) procedures for this inspection are similar to those used at other power stations. A similar relief request was granted for the Pilgrim Nuclear Power Station (TAC No. M93724).
In order to effectively plan for the Fall 1998 refueling outage, the District requests NRC approval of this request by September 30,1998.
Should you have any questions concerning this matter, please contact me.
Sincerely,
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S John IL Swailes O
Vice President of Nuclear Energy 9809020209 900831 PDR ADOCK 05000298
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PDR Attachments Cooper Nuclear Station PO. Box 98/ Brownville. NE 68321-0098 Telephone: (402) 825-38n / Fax: (402) 825-s2n o
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Augusi 31; 1998 Page 2 0f 2 '
cc: Regional Administrator USNRC - Region IV Senior Project Manager USNRC - NRR Project Directorate IV-1
. Senior Resident Inspector USNRC NPG Distribution l
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Attachment I to NLS980133 Page1of3 INSERVICE INSPECTION RELIEF REQUESTS i
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RELIEF REQUEST NUMBER RI-04, REVISION 0 i
COMPONENT IDENTIFICATION Code Class:
1
References:
IWB-2500, Table IWB-2500-1 Examination Category:
B-A Item Number:
Bl.11, Bl.12, and Bl.30
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Description:==
Inspection of the Reactor Vessel Circumferential and Longitudinal Shell Welds, and Shell to Flange Weld Component Numbers:
VLA-BA-1, VLA-B A-2, VLA-BA-3, VLB-B A-1, VLB-B A-2, VLB-B A-3, VLC-BB-1, VLC-BB-2, VLC-BB-3, VLD-BB-1, VLD-BB-2, VLD-BB-3, VCB-BB-1, VCB-BA-2, VCB-BB-3, VCB-BB-4, VCB-BC-5 CODE REQUIREMENT ASME Section XI 1989 Edition Table IWB-2500-1 requires a volumetric examination of the beltline region shell circumferential and longitudinal welds and the shell to flange weld.
HASIS FOR RELIEF l
The Cooper Nuclear Station Reactor Pressure Vessel has limited access from the outside diameter for ultrasonic inspection. This has resulted in the need to perform an automated weld inspection from the inside diameter. Based on equipment limitations and proven results, Cooper has selected the GERIS 2000 to perform the examination. This equipment does not meet the explicit requirements of ASME Section V or Regulatory Guide 1.150 Revision 1 for examination technique. The proposed alternate ultrasonic examination technique, known as PDI (Performance Demonstration Initiative), provides an acceptable level of quality and examination repeatability as compared to the code requirements.
The remote examinations will be performed using the GERIS 2000 system in accordance with PDI approved techniques and procedures. The procedures were demonstrated at the Performance Demonstration Initiative (PDI) qualification Session No. 61-02 in accordance with ASME Section XI, Appendix Vill,1992 Edition,1993 Addenda. The examination and sizing procedures use echo-dynamic motion and tip diffraction characteristics of the flaw instead of the amplitude characteristics required by the ASME Code. The same straight and angle beam search units will interrogate the examination volume as an ASME Section V, Article 4 procedure. In addition, examination using a 70 degree refracted longitudinal search units will be performed.
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Attachment I to NLS980133 Page 2 of 3 INSERVICE INSPECTION RELIEF REQUESTS RELIEF REQUEST NUMBER RI-04, REVISION 0 BASIS FOR RELIEF (Continued)
The General Electric Company received written notification verifying successful completion of the Performance Demonstration Initiative in May 1997 for the examination procedure and December 1996 for the flaw sizing procedure.
The PDI procedures do not comply with ASME Section XI paragraph IWA-2232, ASME Section V Article 4, or USNRC Regulatory Guide 1.150. The examination and sizing techniques are considered an alternative method that provides a higher quality result than ASME Section XI. An attachment titled "GERIS 2000 Invessel System Alternate Method for Compliance to Regulatory Guide 1.150," dated March 1997, is provided for supporting information. The examination and sizing procedures are available for review upon request.
A comparison between the ASME Section V based ultrasonic methods and procedures developed to satisfy the Performance Demonstration Initiative (PDI) can be described as a comparison between a compliance-based procedure (ASME Section V) and a results-based procedure (PDI).
ASME Section V procedures use an amplitude-based technique and a known reflector. The ultrasonic method was established independently from the acceptance standards for flaw size found in ASME Section XI. The PDI sizing method is considered more accurate than the method used in ASME Section V.
The PDI process specifies the required results of the examination. The PDI qualification method is based on a group of samples, which validate the acceptable flaw sizes in ASME Section XI.
The sensitivity to detect these flaws is considered to be equal to or greater than the sensitivity obtained through ASME Section V because the PDI process requires the detection of diffracted signals whereas the Section V procedures rely on the larger specular reflectors. Qualified Level III data analysts using the applicable PDI qualified procedure will perform analysis and sizing of indications.
Regulatory Guide 1.150 " Ultrasonic Testing of Reactor Vessel Welds during Preservice and Inservice Examinations" initiated a change in ultrasonic examination procedures to a results-based procedure. The regulatory guide was instrumental in the development of the ASME Section XI, Appendix VIII methodology and the PDI. 110 wever, the regulatory guide does not I
provide a structure for procedure demonstration and therefore allows for various interpretations
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of the examination results. Also, the regulatory guide does not provide for a number of samples, I
a blind test or an acceptable level of performance, all of which are addressed in the PDI process.
i The PDI program, based on ASME Section XI Appendix Vill, requires the ultrasonic equipment, procedures and examiners be tested on flawed and notched materials and configurations similar to those found in actual plant conditions.
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I Attachment I to NLS980133 Page 3 of 3 I
INSERVICE INSPECTION RELIEF REQUESTS RELIEF REQUEST NUMiiER RI-04, REVISION 0 HASIS FOR RELIEF (Continued)
The use of PDI qualified procedure results in a more sensitive examination for the detection of I
potential flaws than the code described techniques. The error band for sizing has been established within the limits of Appendix VIII. The inspection method's capability to reliably detect flaws in the areas of restricted access was satisfactorily demonstrated at the PDI session.
This capability increases the effective coverage of the required examination volume.
PROPOSEI) ALTERNATIVE The automated RPV shell weld and shell to flange weld examinations shall be performed using l
PDI examination techniques in accordance with ASME Section XI, Appendix Vill,1992 Edition,1993 Addenda in lieu of or in addition to ASME Section XI,1989 Edition examination techniques.
Al'PLICAllLE TIME PERIOD l
Reliefis requested for the balance of the Third Ten-year interval.
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