ML19322A775
| ML19322A775 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/01/1966 |
| From: | DUKE POWER CO. |
| To: | |
| References | |
| NUDOCS 7911210796 | |
| Download: ML19322A775 (7) | |
Text
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- APPENDIX SE LINER PL\TE TECHNICAL SPECIFICATIONS
- 1. SCOPE This specification is for the design, fabrication, erection, and testing of the steel liner plate for the Reactor Building.
The Reactor Building will be used to house a nuclear reactor and other equip-ment as part of a nuclear power plant. As this building is to prevent the escape of radioactive material, the highest integrity is required.
- 2. TYPICAL DETAILS Typical details of the liner plate are shown on Figure 5-1. Typical details of penetrations are shown in Figures 5-2 and 5-3.
- 3. CODES All components of the liner which must resist the full design pressure, such as penetrations, shall be designed, constructed, inspected and tested in com-plete conformance with the requirements of Subsection B of Section III, Nuclear Vessels, of the ASME Boiler and Pressure Vessel Code, applicable portions of Part UW, " Requirements for Unfired Pressure Vessels Fabricated by Welding,"
of Section VIII of the ASME Boiler and Pressure Vessel Code and these speci-s~s fications. The liner plate shall conform to requirements of ASTM A36, "Speci-fication for Structural Carbon Steel," or A442, Grade 55, Flange Quality " Car-bon Steel Plates with Improved Transition Properties." Structural shapes will be supplied to che requirements of ASTM A36 and ASTM A6, " Specification for General Requirements for Delivery of Rolled Steel Plates, Shapes, Sheet Piling and Bars for Structural Use."
3s' Specifically, paragraphs UW-26 through UW-34, (Section VIII) inclusive will apply in their entirety. In addition, the qualification of welders will be performed in accordance with Appendix 5D, " Quality Control." Qualifications
- and duties of the field inspectors are listed in Appendix 3D, " Quality Con-trol."
Radiographic inspection of the liner plate welds, for quality control, will be in accordance with paragraph UW-51 of Section VIII of the ASME Boiler and '
Pressure Vessel Code. Dye penetrant inspection of liner plate welds, also for quality control, will be in accordance with Appendix VIII, " Methods for Liquid Penetrant Examination," of Section VIII of the ASME Boiler and Pres-sure Vessel Code.
- 4. PENETRATIONS At all penetrations, the liner plate will be thickened to reduce stress con-centrations in accordance with the ASME Boiler and Pressure Vessel Code -
Section III, Nuclear Vessels. The thickened portion of the liner plaiv will
,-s then be anchored to the concrete by use of anchor studs completely around the penetrations. The sleeva, pipe cap and all welds associated with the pene-('~- trations will be designed to resist all loads including prestress forces and and internal design pressure.
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- 5. CONSTRUCTION SEOUENCE The side wall steel liner plate is also used as the interior form for the prestressed concrete wall. The liner plate will be suitably stiffened and braced to maintain the specified curvature within acceptable limits. The liner plate is erected in a series of horizontal courses preceding each vertical lif t of concrete, up to the ring girder. A temporary steel truss structure is used to support the dome liner plate during construction.
The bottom liner plate on the foundation slab will be installed at times when there will be the least interference with other construction operations, and it will be protected from damage by all concurrent or subsequent construction operations. It will be permanently protected by an adequate thickness of concrete floor slab placed over the lining. All weld seams which are covered by concrete or are otherwise made inaccessible will have channels welded over the seams to make possible future leak testing.
All penetrations of the liner plate will be shop-fabricated assemblies. The penetrations will be shop welded to the liner plate or field welded. The method to be selected will be the one which best protects the integrity of the penetration assembly during shipment and erection while providing a weld to the liner plate meeting all requirements.
- 6. DESIGN CONDIT70NS The design criteria which will apply to the Reactor Building liner to meet the specified leak rate under accident conditions shall be as follows:
- a. That the liner be protected against damage by missiles.
- b. That the liner plate strains be limited to allowable values that have been shown to result in leak tight vessels or pressure piping.
- c. That the liner plate be prevented from develop 8ing significant distortion.
- d. That all discontiauities and openings be well anchored to accommodate the forces exerted by the restrained liner plate. That careful attention be paid to details of corners and connections to minimize the effects of discontinuities.
- 7. DESIGN BASIS The most applicable basis for establishing allowable liner plate strains is considered to be that portion of the ASME Boiler and Pressure Vessel Code,Section III, Nuclear Vessels, Article 4. Specifically, the following sections will be adopted as guides in establishing allowable strain limits.
Para. N-412 (m) Thermal Stress (2)
Para. N-414.5 Peak Stress Intensity Table N-413 Fig. N-414, N-415 (A)
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Para. N-412 (n)
Para. N-415.1 Implementation of the ASME design criteria requires that the liner material be prevented from experiencing significant distortion due to the thermal load and that the stresses be considered from a fatigue standpoint. (Para. N-412 (m) (2).
- 8. ACCIDENT CONDITION Establishing an allowable strain based on the one significant thermal cycle of the accident condition would permit an allowable stra.in (from Fig. N-415A) of approximately 2 percent. The strain in the liner plate at yield will be approximately 0.1 percent. The liner plate will be allowed to go beyond yield strains during the accident condition. Maximum allowable tensile or compres-sive strain has been conservatively set at 0.5 percent (compared to 2 percent shown above).
- 9. LOADINGSL The following fatigue loads will be considered in the design of the liner plate:
- a. Thermal cycling due to annual outdoor temperature variations. Daily temperature variations will not (O,/
- penetrate a significant distance into the conrete shell to appreclably change the average temperature of the shell relative to the liner plate. The number
, of cycles for this loading will be 40 cycles for the l plant life of 40 years. ,
- b. Thermal cycling due to containment interior temperature J
varying due to shutdown and startup of the reactor system.
The number of cycles for this loading will be assumed at 500 cycles,
- c. Thermal cycling due to the loss of coolant accident will be assumed at one cycle.
Thermal and load cycles in the piping systems are somewhat isolated from the liner plate penetrations by the concentric sleeves between the pipe and the liner plate. The attachment sleeve will be designed in accordance with ASME Section III fatigue considerations. All penetrations will be reviewed for a conservative number of cycles to be expected during the plant life.
- 10. MATERIAL The liner plate, which acts as a leak tight membrane, plus the structural shapec ,
l to support the liner are ASTM A36 or ASTM A442. The selection of this material complies with the " Safety Standard for Design, Fibrication and Maintenance of p Steel Containment Structures for Stationary Nuclear Power Reactors" prepared by Subcommittee N6.2, Containment, of ASA Sectional Committee N6, Reactor Safety V
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Standards. Section 12 of this standard, " Steel Linings for Parts of Contain-ment Structures M*?; of Other Materials", states in part, " Weldable quality structural plate material is satisfactory."
The liner plate is designed to function only as a leak tight membrane. It is not designed to resist the tension stresses from internal applied pressure which may result from any credible accident condition. The structural integrity of the containment is maintained by the post tensioned concrete portion of the building. Since the only applied stresses to the liner plate membrane, from shrinkage and creep of the concrete, will be in compression and significant applied tension stresses are expected from internal pressure loading, there is no need to apply special nil ductility transition temperature criteria to the liner plate material.
All components of the liner which must resist the full design pressure, such as penetrations, are selected to meet the requirements of paragraph N-1211 of Section III, Nuclear Vessels, of the ASME Code. ASTM A516 grade 60 or 70 made to e.STM A300 is typical of a steel which meets these requirements and will be used as a plate material for penetrations. This material has excellent weld-ability characteristics and as much ductility as is obtainable in any commercially available pressure vessel quality steel. In accordance with ASNE Code Case 1347, allowable stresses for A516 grade 60 and 70 are the same as those permitted for A201 grade B and A212 grade B, respectively.
- 11. LINER ANCHORAGES The anchorage system will be designed to prevent instability of the liner plate to resist any differential loads due to local relaxation, and to limit inward deflection due to construction loads. The liner plate will be anchored at all discontinuities to eliminate excessive strains at the discontinuities. The stability of the liner plate will be provided by stif fening and anchoring the plate to the concrece. See Figure 5-1 for typical details of liner plate anchorages.
- 12. LiELDING Inspection procedures to be employed for the liner seam welds, liner fastening and around penetrations shall consist of visual inspection, radiography, dye penetrant testing and vacuum box soap bubble testing.
100 percent of the welding shall be visually examined by a qualified inspector responsible for welding quality control. The criterion for workmanship and visual quality of welds shall be as follows:
l Each weld shall be uniform in width and size throughout its full length. Each layer of welding shall be smooth and shall not contain more than acceptable limits of slag, cracks , pinholes , and undercut, and shall be completely fused to the adjacent weld beads and base metal. In addition, the cover pass shall be free of coarse ripples, irregular surface, non uniform bead pattern, high l crown, and deep ridges or valleys between beads. Peening of welds will not be l permitted.
Butt welds shall be of multipass construction, slightly convex, of uniform-height, and have full penetration.
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Fillet welds shall be of the specified size with full throat and legs of F- uniform length. Radiography will be used as an aid to quality control. The primary purpose of the liner plate and the welds therein is to provide leak tightness integrity to the post-tensioned concrete reactor building. Structural integrity of the building is provided by the post-tensioned concrete and not by the liner plate. Radiography is not recognized as an effective method for examining welds to assure leak tightness. Therefore, the only benefit which can be expected from radiography in connection with obtaining leak tight welds is an aid to quality control. Radiographs of each welder's work will provide structural verification that the welding is or is not under control and being done in accordance with the previously established and qualified procedures. Addi-tionally, employing radiography to inspect each welder's work has been proved by past experience to have a positive psychological effect on improving overall welding workmanship. The criterion for radiographic techniques shall be in accordance with para-graph UW-51 of Section VIII of the ASME Code. Radiographs shall be taken for at least one foot in each 50 feet of welding completed in the flat, vertical, horizontal, and overhead positions by each welder. , Dye penetrant inspection will also be used as an aid to quality control. The field welding inspectors will use dye penetrant inspection to closely examine welds judged to be of questionable quality on the basis of the initial visual J inspection. Also, dye penetrant inspection will be used to confirm the com-plete removal of all defects from areas which have been prepared for repair welding.
- 13. TESTING FOR LEAKS Pneumatic proof tests will be performed by Duke to demonstrate the integrity of the liner plate. Compressor capacity will be furnished to raise the pres-sure at least 1 psi per hour. A hydrostatic test will not be performed.
In the unlikely event that excessive leakage should occur during initial test-ing, the following steps would be taken as required to locate the leaks.
- 1. Pressurize all locks and penetrations capable of being individually pressurized and hunt for leaks in welded seams and gaskets using soapsuds or equivalent means.
- 2. Evacuate the ieactor building to about 2 psig vacuum and hunt for leaks in welded seams in walls and dome by soapsuds.
- 3. Pressurize seams in the floor liner under the concrete i fill using pressure taps connected to leak detection channels.
If leakage in an area is indicated, the concrete in the affected area will be removed and the leak further localized by soapsuds testing o r equivalent means. ~S 1 .
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The means of repair would depend on the location and magnitude of the leak but would probably consist of gouging and rewelding a defective weld or seal welding a steel patch. All repairs will be carried out utilizing the same high standards and control exercised in the initial construction. The repaired area will be locally tested by vacuum box or soapsuds method whichever is appropriate and the entire reactor building given another integrated leak rate test to ensure liner plate integrity and compliance with the leakage requirements. Measurement of the liner strain under test loading is described in Appendix 5F, " Reactor Building Instrumentation". Resistance strain gauges will be located around openings, boundaries and other pertinent areas, to measure strain at both faces of the liner. The use of a well-restrained mild steel liner plate of relatively low strain behavior will ensure that the leak tightness of the liner plate at accident conditions will not change from that in the test condi-tions. The strain measurements of the liner plate are being taken to observe structural behavior and bear no relation to leakage behavior. O 1 9 SE-6 l 0009. 349}}