ML041730543
| ML041730543 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 05/26/2004 |
| From: | Mahesh Chawla NRC/NRR/DLPM/LPD3 |
| To: | Vincent D Nuclear Management Co |
| Chawla M, NRR/.DLPM, 415-8371 | |
| References | |
| TAC MC2543, TAC MC2544 | |
| Download: ML041730543 (2) | |
Text
From:
Mahesh Chawla To:
Dale Vincent Date:
5/26/04 5:37PM
Subject:
Request For Additional Information - RR#19 - MC2543/MC2544 This is in reference to your above request by letter dated March 30, 2004, for relief from the requirements of Section XI, IWB-2500 of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. NMC proposed to use the alternative examination volume of ASME Code Case N-613-1.
The staff has reviewed the proposed alternatives and has determined that following additional information is required in order to complete the evaluation. Please let me know your availability to discuss this information with the NRC staff.
- 1. Under the Basis for Relief Request, NMC states that the required examination volume for the RPV nozzle-to-vessel welds extends far beyond the weld into the base metal, and is unnecessarily large. This proposed alternative would redefine the examination volume boundary to one-half (1/2) inch of base material on each side of the widest portion of the weld.
- a. Please provide a supplemental sketch showing the specific configuration nozzle-to-vessel weld and revised examination volume (including dimensions).
- b. Identify the type of ultrasonic technique (manual or automated), nominal pipe diameters, and weldment material (ferritic, austenitic, Inconel) that NMC is proposing to inspect.
- c. It is not clear how NMC personnel will be able to locate the widest portion of the nozzle-to-vessel weld precisely. It is unclear how repaired areas extending beyond the ideal weld cross-sectional area are identified and how these areas will be examined. If personnel are to identify the widest sections of the nozzle-to-vessel welds, please specify what positive means of examination will be used to identify the weld extremities. Also, will the extremities be identified on both the inside and outside diameters of the nozzle to ensure complete coverage of the welds?
- 2. Under the Basis for Relief Request, NMC also states that crack initiation during plant service in the examination volume excluded from the proposed reduced examination volume is highly unlikely because of the low stresses encountered in the base material outside of the heat affected zone of the weld. Please provide your technical basis and analyses in order to support this statement.
CC:
Veronica Rodriguez Mail Envelope Properties (40B50E24.22E : 15 : 21352)
Subject:
Request For Additional Information - RR#19 - MC2543/MC2544 Creation Date:
5/26/04 5:37PM From:
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