ML20117H585
| ML20117H585 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 05/17/1996 |
| From: | Maxfield G WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| PBM-96-0117, PBM-96-117, NUDOCS 9605280267 | |
| Download: ML20117H585 (3) | |
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,'O Wisconsin Electnc POWER COMPANY Point Booch Nuclear Plant 6610 Nuclear Rd. Two Rkors. WI 54241 (414) 755-2321 PBM 96-0117 May 17,1996 Document Control Desk U. S. NUCLEAR REGULATORY COMMISSION Mail Station Pl 137 Washington, DC 20555 Gentlemen:
DOCKET 50-301 ASME SECTION XI REI IEF REOUEST RR-2-22 POINT BEACH NUCLEAR PLANT. UNIT 2 in accordance with 10 CFR 50.55a(g)(5)(iv), Wisconsin Electric Power Company requests relief from Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code," Rules for Inservice Examination of Nuclear Power Plant Components," 1986 edition, no addenda. The requirements for which ieliefis requested apply to the third inservice inspection interval for Point Beach Nuclear Plant, Unit 2. The third interval began in December 1992 for Unit 2.
The attached relief request, RR-2-22, provides the information needed for the NRC to complete a review and approval as required.
Sincerely, Greg Maxfie d Plant Manager caw Attachment 280030
,[t' 9605280267 960517 PDR ADOCK 05000301
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RE-2::22 COMPONENT Steam Generators A & B EXAM AREA Shell-to-Tubesheet weld Shell-to-Head weld FW Nonle-to-Shell weld FW Nonle Inner Radius Exam ISOMETRIC ISI-PRJ-2201 ASME SECTION XI CATEGORY C-A ( Shell-to-Tubesheet and Shell-to-licad welds)
C-B (FW Nonle-to-Shell and Inner Radius Exam)
ASME SECTION X1 ITEM NUMBER Cl.20 - Shell-to-Head weld Cl.30 - Shell-to-Tubesheet weld C2.21 - FW Nonle-to-Shell weld C2.22 - FW Nonle Inner Radius Exam AStdE SECTION XI REOUIREMENT Cl.20/Cl..'80 - Volumetric C2.21 - Surface and Volumetric C2.22 - Volumetric IWC-2200 states that (b)" Shop and field examinations may serve in lieu of the on-site preservice examinations, provided: (1) in the case of vessels only, the hydrostatic test required by Section Ill has been completed" ALTERNATE REOUIREMENT The required volumetric and surface examinations will be completed. The proposed alternate examination is to utilize shop and field examinations in lieu of preservice examinations that will be performed pliar to the hydrostatic test required by Section Ill. All other requirements ofIWC-2200 will be met in their entirety.
REASON FOR PROPOSED ALTERNATE REOUIREMENT I
PBNP Unit 2 will be replacing both the A and B Steam Generators during the U2R22 outage (Fall 1996).
The replacement Steam Generators will arrive on site in two halves and a feedwater nonle extension and require additional Section Ill construction prior to the Section 111 hydrostatic test. The addiie.1 construction required is the completion of a girth weld in the steam drum and a nonle-to-r, vede extension i
weld. Upon completion of these welds, and the welds attaching the steam generators to exi.dng plant l
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e systems, the Section 111 hydrostatic test will be performed in place utilizing existing plant system to attain hydrostatic test pressure.
it is desired to perform the preservice examinations required by IWC-2200 in the shop prior to final installation (and Section 111 hydrostatic test). He reason for this is to reduce radiation exposure and potential personnel industrial safety concerns. Due to size concerns of the steam generators it is not practical to complete the ASME Section Ill construction of the two halves of the vessels, and the feedwater nozzle, outside of the containment building. De completed steam generators cannot physically fit through the existing equipment hatch. To maintain the integrity of the containment structure the steam generators will be moved through the equipment hatch in three components; the lower half, upper half (steam drum) l and feedwater nozzle extension. The components will be put in place and the final Section 111 welds will be completed.
He radiation exposure associated with preservice examinations in the shop will be zero. If the preservice i
examinations are performed after the replacement steam generators are welded into place, radiation exposure from existing plant systems and components will cause exposure to the examining technicians.
The radiation exposure associated with doing preservice examinations with a single steam generator in place is estimated as follows:
,WgM Est Rad. Field Duration of exam Funosure/nerson Shell-to-Tubesheet 50 mr/hr 6 hrs.
300 mrem Shell-to-licad 5 mr/hr 6 hrs.
30 mrem i
Nozzle-to-Shell 10 mr/hr 2 hrs.
20 mrem Nozzle Inner Radius 10 mrem /hr I hr.
10 mrem Total 360 mrem i
Based on 2 NDE technicians performing the work, the radiation exposure received is estimated to be 720 mrem per steam generator associated with the preservice examination. For completion of both steam generators, the radiation exposure is estimated to be around 1440 mrem. Any indications that require further characterization will result in additional exposure, in addition, to perform the Shell-to-Head examination, a significant amount of scaffolding erection is required to provide access to this weld. While a substantial effort will be made to ensure personnel safety for the NDE technicians working from the scaffolding platform, a certain degree ofindustrial safety risk is assumed when performing this examination in the field. Performing the preservice examination of this weld in the shop will reduce the industrial safety to the examining personnel.
By implementing this relief request, all the required ASME Section XI preservice examinations would be performed in accordance with the ASME Code. The specific relief requested is to perform these examinations prior to the ASME Section 111 hydrostatic test rather than after the hydrostatic test. This approach is allowed for piping welds under current ASME Section XI rules. This relief request is an extension of this approach to the vessel welds for the replacement steam generators. By granting this relief and allowing preservice examinations to be performed in the shop, there will be a reduction in the radiation exposure and an increase in personnel safety associated with performing the preservice inspection of the welds in place.
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