ML20205A663
| ML20205A663 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 04/22/1985 |
| From: | Capstick R VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Thompson H Office of Nuclear Reactor Regulation |
| References | |
| FVY-85-36, GL-84-07, GL-84-7, NUDOCS 8504260017 | |
| Download: ML20205A663 (10) | |
Text
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e VERMONT YANKEE NUCLEAR POWER CORPORATION RD 5. Box 169, Ferry Road, Brattleboro, VT 05301
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ENGINEERING OFFICE April 22, 1985 1671 WORCESTER ROAD FRAMINGHAM, MASSACHUSETTS 01701
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FVY 85-36 TELEPHONE 617-872-8100 United States Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Office of Nuclear Reactor Regulation Mr. H. L. Thompson, Director Division of Licensing
References:
(a) License No. DPR-28 (Docket No. 50-271)
(b) Generic Letter 84-07, USNRC to All Licensees of Boiling Water Reactors, NVT 84-53, dated March 14, 1984
Subject:
Scope of Vermont Yankee's Recirculation System Pipe Replacement Program
Dear Sir:
Vermont Yankee Nuclear Power Corporation herein provides information pertaining to the replacement of the Recirculation System and portions of the Residual lleat Removal (RHR) System at Vermont Yankee. The replacement of the existing 304 stainless steel material with controlled chemistry 316 material for improved IGSCC resistance is scheduled to begin in September 1985.
The attachment to this letter describes the engineering, design, procurement, removal, and installation activities associated with the pipe replacement program. 'As discussed in the attachment, a 10CFR50.59 review has been performed which determined that the piping system replacement does not constitute an unreviewed safety question. The pipe stress analysis has been performed using PVRC damping, in accordance with ASME Code Case N-411.
As discussed in Section 3.4 of the attached report, piping systems will be analyzed to verify that there are no interferences to restrict free motion during a nelsmic event.
A description of the radiation protection program, as requested by Generic Letter 84-07 [Rnference (b)), for the pipe replacement effort will be nuhmitted by June 1, 1985 and will include a description of the preplanning procedures, shielding, equipment, personnel training, estimated total cumulative doso, and other measures initiated to keep exposures as low as reasonably achievable. Current studios show that the estimated exposure will be below 2,000 person-rem.
8504260017 850422 Mj PDR ADOCK 05000271 P
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United States Nuclear Regulatory Connaission April 22, 1985 Attention:
Mr. H. L. Thompson Page 2 We trust this information is satisfactory; however, should you have any questions or require additional information, please contact us.
Very truly yours, VERMONT YANKEE NUCLRAR POWER CORPORATION v
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/b R. W. Ca tick Litansing Engineer RWC/gms
t ATTACHMRNT 1
1.0 INTRODUCTION
1.1 PurPOS9 This document describes the activities and system design associated with the replacement of the Recirculation System and portions of the Residual Heat Removal (RHR) System at Vermont Yankee.
1.2 Scope This submittal describes the engineering, design, procurement, removal, and installation of the Recirculation and RNR Systems.
2.0 PROJECT DESCRIPTION The project task is to replace existing 304 stainless steel material with controlled chemistry 316 material for improved ICSCC resistance.
2.1 Overall Ormanization The project is organized with Vermont Yankee providing overall direction to the engineers and contractors involved. A dedicated project team has been formed with responsibility for the engineering, construction, design, procurement, disposal, and quality assurance activities for the project.
Each engineer or contractor will perform his work under his quality assurance program, which will be reviewed and approved by the project team.
The replacement will be performed as an Engineering Design Change Request (EDCR) under the Yankee Operational Quality Assurance Progras (YOQAP-1).
2.2 Engineerinz Engineering services will be provided by organizations selected by Vermont Yankee. Piping analysis and related support services will be provided by the General Electric Company.
2.3 Installation Contractor A
The piping installation will be performed by Morrison-Knudsen.
2.4 Support Services 2.4.1 Quality Assurance Each engineer and contractor provides the required quality control and quality assurance services for items within his scope of work.
In addition, Vermont Yankee, via the Yankee Nuclear Services Division, will provide periodic audits of the project's participants to verify compliance with contractors' QA/QC plans and procedures.
2.4.2 Health Physics The required health physics controls will be established by Vermont Yankee. Vermont Yankee will be responsible for implementing the health physics program, with assistance from Morrison-Knudsen as required.
2.4.3 Consultants Additional consultants may be retained to provide specific expertise or supplement the activities of the project team personnel.
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1 3.0 ENGINgERING ASPECTS OF PROJECT 3.1 Material Considerations In order to improve the IGSCC resistance of the replacement systems, the original Type 304 wrought material will be replaced with controlled chemistry Type 316 seamless pipe and fittings.
The in-drywell components to be replaced are:
1.
Jet pump inlet nozzle safe ends.
2.
Recirculation suction nozzle safe ends.
3.
All wrought recirculation system piping and components.
4.
Recirculation bypass line.
5.
Wrought stainless steel portions of the RHR System.
6.
Reactor vessel bottom head drain.
The material chemistry requirements are shown in Table I.
All reused components, such as pumps and valves, will be weld clad at the weld interface, if required, to ensure that the HAZ region is protected by material having a ferrite number of 8FN minimum.
3.2 Design Considerations The replacement Recirculation System has been redesigned to reflect advancements in piping system design. Specific design improvements include:
1.
Use of seamless material to eliminate longitudinal welds.
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.Useohintegrallyforgedfittingsandbentpipetoeliminatewelds.
2.
3.
Deletion of ring header end caps to eliminate crud traps.
4.
Deletion of loop crosstie valves to eliminate crud traps.
5.
Improved ID counterbore to facilitate ISI.
6.
. Cylindrical prolongation on all fittings to facilitate ISI.
7.
Surface pretreatment to minimize future radiation buildup is under consideration.
A schematic of the new Recirculation System design is shown in Figure 1.
3.3 -Fabrication Considerations I
Tight controls have been imposed on the fabrication process to ensure that the IGSCC resistance of the material is not degraded during fabrication.
Material test coupons subjected to actual fabrication processes will be tested to ensure the required physical and IGSCC resistance properties are achieved.
3.4 Analysis considerations The replacement piping system will be reanalyzed in accordance with the rules of ANSI B31.1, which was the original analysis code. The 1977 Edition has been selected to provide consistency with the Vermont Yankee seismic piping upgrade progerm on piping outside containment.
The seismic input will be based on a safe shutdown earthquake anchored at 0.14g, as specified in the original plant design. However, the ground 4
r response will be based upon USNRC Regulatory Guide 1.60, which is more severe than the original design basis.
Other analysis upgrades include 3D versus 2D earthquake and extension of the cutoff frequency to 33 Hz versus 20 Hz.
J Structural damping will be based on USNRC Regulatory Guide 1.61 requirements, except for piping which will utilize PVRC damping as defined by ASME Code Case N-411 and as recommended by NUREG-1061.
3.5 Codes and Standards _
All material and fabrication requirements for the replacement systems will meet the requirements of the ASME Code Section III, 1980 Edition through Summer 1982 Addenda. This requirement is consistent with Section XI and exceeds the original construction requirements for Vermont Yankee.
As stated earlier, the analysis codc will be B31.1, 1977 Edition. The material and fabrication requirements meet or exceed the requirements of B31.1, 1977.
4.0 FABRICATION AND CONSTRUCTION ASPECTS OF PROJECT 4.1 Weld Joint Design Weld joint designs will be selected to provide joints with an acceptable minimum of weld-induced residual stress. All circumferential butt-shop welds will be solution annealed to eliminate welding residual stresses.
4.2 Mock-Ups and Training An extensive mock-up and training program will be conducted. Mock-ups will be developed for the following areas: ;
1 1.
2.
3.
Recirculation inlet-safe-end thermal sleeve weld.
4.
Bottom head drain replacement.
All personnel will be trained on mock-ups before performing production welds.
5.0 DESIGN CONTROLS 5.1 Engineerina Desian Change The replacement of the recirculation and RHR piping is being performed as an Engineering Design Change Request (EDCR) under the provisions of the Yankee Operational Quality Assurance Program (YOQAP-1).
Engineering specifications have been prepared for the following activities:
1.
Piping material procurement and fabrication.
2.
Safe-end material procurement and fabrication.
3.
Site installation of replacement piping systems.
4.
Analysis requirements for replacement piping systems.
5.
Recirculation loop flow elements.
6.
Replacement thetual insulation.
5.2 50.59 Review A 50.59 review has been performed and documented as part of the RDCR package. It has been detet1 mined that the piping system replacement does not constitute an unreviewed safety question as defined by 10CFR50.59.
6.0 ALARA CONSIDERATIONS The ALARA aspects of the project will be discussed in a separate report, as required by USNRC Generic Letter 84-07.
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