1、BRITISH STANDARD BS 4975:1990 Specification for Prestressed concrete pressure vessels for nuclear engineering UDC 621.039.536.2:624.95.012.46:693.56:666.982.4BS4975:1990 This British Standard, having been prepared under the directionof the Nuclear Engineering Standards Policy Committee, was publishe
2、d underthe authority of the BoardofBSI and comes into effect on 30March1990 BSI 02-2000 First published July1973 First revision March1990 The following BSI references relate to the work on this standard: Committee reference NCE/3 Draft for comment 87/77290 DC ISBN 0 580 17381 X Committees responsibl
3、e for this British Standard The preparation of this British Standard was entrusted by the Nuclear Engineering Standards Policy Committee (NCE/-) to Technical Committee NCE/3, upon which the following bodies were represented: BEAMA Ltd. British Nuclear Fuels plc. Electricity Supply Industry in Englan
4、d and Wales Health and Safety Executive Institution of Civil Engineers Institution of Nuclear Engineers Institution of Structural Engineers Power Plant Association Power Plant Contractors Association South of Scotland Electricity Board United Kingdom Atomic Energy Authority Amendments issued since p
5、ublication Amd. No. Date of issue CommentsBS4975:1990 BSI 02-2000 i Contents Page Committees responsible Inside front cover Foreword iii Section 1. General 1.1 Scope 1 1.2 Definitions 1 1.3 Basic considerations 3 1.4 Responsibilities 5 1.5 Information and requirements to be agreed and to be document
6、ed 6 1.6 Interpretation 8 Section 2. Materials 2.1 Concrete 9 2.2 Reinforcement 9 2.3 Prestressing system 10 2.4 Liners (including supported penetration liners) 10 Section 3. Design 3.1 General 11 3.2 PCPV structure 11 3.2.1 Design considerations 11 3.2.2 Analysis for service load conditions 13 3.2.
7、3 Permissible stresses in concrete and reinforcement 14 3.2.4 Ultimate load analysis 15 3.3 Liners (including supported penetration liners) 16 3.3.1 General 16 3.3.2 Effects of irradiation 17 3.3.3 Design of liner 17 3.3.4 Design of ties and shear connectors 17 3.3.5 Design of corners 18 3.3.6 Desig
8、n of penetration liners supported by concrete 18 Section 4. Manufacture 4.1 Concrete 19 4.2 Reinforcement 19 4.3 Prestressing system 19 4.4 Liners (including supported penetration liners) 20 Section 5. Inspection and tests 5.1 Concrete 21 5.2 Reinforcement 21 5.3 Prestressing system 21 5.4 Liners (i
9、ncluding supported penetration liners) 23 Section 6. Steel closures and unsupported penetrations 6.1 General 24 6.2 Materials 24 6.3 Design 24 6.4 Manufacture 24 6.5 Monitoring and inspection 24 6.6 Restrictors 24BS4975:1990 ii BSI 02-2000 Page Section 7. Insulation and cooling systems 7.1 General 2
10、5 7.2 Fault analysis 25 Section 8. Automatic pressure relief devices 8.1 Automatic pressure relief devices 26 Section 9. Testing and surveillance of completed structure 9.1 Vessel proof test 27 9.2 Vessel leak test 27 9.3 Vessel vacuum test 27 9.4 Surveillance 27 Appendix A Simplified concepts of th
11、e development and analysis of stresses in a PCPV 29 Appendix B Design and methods of analysis 30 Appendix C Local stresses 34 Appendix D Design limits for multiaxial compressive stresses in concrete 36 Appendix E Ultimate load conditions 38 Appendix F Corrosion protection of prestressing tendons 38
12、Appendix G Grouting of ducted prestressing tendons 41 Appendix H Effect of fast neutron irradiation on the properties 42 Appendix J Effect of fast neutron irradiation on the mechanical properties of ferritic steels 45 Appendix K Recommended practice for assessment of liners (including supported pene
13、tration liners) subject to fatigue 46 Appendix L Construction of control charts for testing wire, strand and bar 52 Appendix M Optional documentation for supply with the vessel 53 Appendix N References 54 Figure 1 Design limits for multiaxial compression 37 Figure 2 Typical fast neutron dose attenua
14、tion in a PCPV wall 43 Figure 3 Effect of irradiation on the dimensional changes of limestone aggregates, cement paste and a limestone aggregate concrete 44 Figure 4 Design fatigue curve for steels for temperatures up to and including 375 C 48 Figure 5 Construction of test fatigue curve 51 Table 1 P
15、rincipal compressive field stresses in concrete 14 Table 2 Permissible stresses in steel reinforcement 16 Publications referred to Inside back coverBS4975:1990 BSI 02-2000 iii Foreword This revision of BS4975 has been prepared under the direction of the Nuclear Energy Standards Policy Committee. It
16、supersedes BS4975:1973 and includes the following significant changes. References to other British Standards have been brought up to date. This applies particularly to BS8110-1 and BS5500 which supersede the “Unified Code”, CP110 and BS3915 respectively. In keeping with current practice elsewhere, p
17、restressing material properties arespecified in terms of characteristic rather than guaranteed values. Additional informative appendices have been included, as follows. a) Appendix K on fatigue assessment of liners combines the methods of BS5500 for strain ranges up to twice yield, with the simplifi
18、ed elastic-plastic method of BS3915 for higher strain ranges, thus avoiding an excessive reliance on fatigue testing or plastic analysis, which might result from a reference to BS5500 alone. b) Appendix J on the effects of irradiation on steel properties provides guidance based on a review of publis
19、hed data. c) Appendix L on the construction of control charts for testing wire, strand and bar gives detailed requirements for quality control of prestressing materials. d) Appendix M on optional documentation for supply with the vessel lists some of the documentation that a manufacturer may be requ
20、ired to supply to the purchaser for permanent record purposes. e) Appendix N gives an up-to-date bibliography. There have been numerous alterations or additions to the specification which derive from15 years to20 years experience in the UK of the design, construction and operation of prestressed con
21、crete pressure vessels (PCPV). For example, the inclusion of fault conditions and hazards; the deletion of the option of limit state design methods; and expansion of the section on in-service surveillance. Sections have been added defining the responsibilities of the purchaser, manufacturer and insp
22、ecting authority and those requirements to be agreed and documented. These sections follow the principles of BS5500. Although the standard is not intended to cover the detailed design of the insulation and the cooling system, some expansion of this section has been considered desirable as a result o
23、f construction, commissioning and operating experience. The format of the specification has been modified to conform to BS0, and more clearly to separate specific requirements from guidance and informative text. The standard specifies the design, construction, inspection and testing of single cavity
24、 and multi-cavity prestressed concrete pressure vessels (PCPVs) for nuclear reactors and makes recommendations for their surveillance. Such vessels have been used for the dual purpose of shielding and containing gas-cooled nuclear reactors and are a form of civil engineering structure requiring part
25、icularly highintegrity. Concrete is weak in tension and is prestressed to counteract tensile stressesinduced by applied loadings. When a PCPV is pressurized and heated the compressive stresses, established during prestressing, are in general reduced, but under normal operating conditions, the concre
26、te stresses remain predominantly compressive.BS4975:1990 iv BSI 02-2000 Prestressing tendons may be placed around the exterior of the vessel structure or passed through ducts inside the concrete. They are usually fabricated from numerous wires or strands and may be anchored by wedge friction grips,
27、by nail heading or by swaged sleeves, which form part of an anchor assembly, bearing on the vessel structure. A circumferential tendon may be formed by winding a single wire or strand under tension many times around the structure or by radially jacking an initially untensioned circumferential tendon
28、 away from the vessel. Very large tendons have been bonded into concrete anchors, the extension on stressing being maintained by placing packing under the anchor blocks. After tensioning, a tendon in a duct may be left with no treatment other than corrosion protection so that the tension in it can b
29、e verified at any time. Detensioning, inspection and, if necessary, renewal of tendons may then be possible. Although the practice is not recommended, the tendon ducts may be grouted. This may have structural benefits but precludes the possibility of inspection, retensioning or renewal of tendons. R
30、einforcement may be incorporated in the concrete to cater for local stresses or to reduce and control the effect of any cracking that may occur. Reinforcement may also be used to increase the ultimate strength of the vessel. The inside surfaces of the vessel are lined to prevent leakage of the react
31、or coolant. The lining will normally be mild steel, anchored, as necessary, to the concrete structure to limit inward buckling and control local accumulations of strain. The liner is normally used as internal shuttering for the vessel during construction. Numerous penetrations through the concrete a
32、nd liner are necessary for reactor fuelling, control and other requirements. In designs where the pressure vessel contains the boilers as well as the reactor, penetrations are required for boiler feed and steam pipes. Such vessels may have apertures giving access to the boilers for installation, ins
33、pection and removal, or separate cavities housing the boiler units. Large penetrations may be required for the circulators in gas-cooled reactors. The vessel liner is extended into the penetrations, which are sealed by steel closures or concrete plugs and may be provided with restrictors or other fl
34、ow limiting devices. If the high temperature of the reactor coolant were applied directly to the liner it could have deleterious effects on the liner and concrete and would induce high thermal stresses in the structure. Acceptable temperatures are maintained by a cooling system, normally attached to
35、 the concrete side of the liner, in conjunction with thermal insulation applied to the internal surface of the liner. Although this standard does not cover decommissioning of the PCPV, the eventual demolition of the structure should be borne in mind at the design stage if simple measures can be intr
36、oduced to ease the problems of demolition. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations
37、. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1to 56, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the insid
38、e front cover.BS4975:1990 BSI 02-2000 1 Section 1. General 1.1 Scope 1.1.1 This British Standard specifies the design, construction, inspection and testing of prestressed concrete pressure vessels (PCPV) for nuclear reactors, including components that are necessary to maintain the structural integri
39、ty and leaktightness of the vessels. However, such concrete pressure vessels are often closely integrated with the operation of the nuclear reactor and its auxiliary plant, and the various parts of the vessel may need to perform functions additional to the structural requirements of this standard. 1
40、.1.2 The safety of concrete pressure vessels depends, firstly, on a correct assessment of the loadings likely to be applied to the vessel and, secondly, on the proper design of the vessel to accept these loadings. This standard covers only the second aspect, the first being the responsibility of the
41、 purchaser who has to meet any statutory or other regulations 1) . 1.1.3 The safety of concrete pressure vessels throughout their service lives also depends on proper operational procedures being adopted and adequate monitoring and inspection of the vessels during service life being carried out. As
42、operational procedures are the responsibility of the operator they are not included in this standard. Monitoring and inspection are dealt with in9.4. 1.1.4 Other components of the reactor pressure circuits, including those parts of the ancillary circuits that, for inspection, can be isolated from th
43、e primary circuit at any time without having to shut down the reactor, shall comply with the relevant British Standards and any additional requirements specified by the purchaser (see1.5). 1.1.5 In addition to the definitive requirements, this standard also requires the items detailed in1.5 to be do
44、cumented. For compliance with this standard both the definitive requirements and the documented items need to be satisfied. NOTE 1Where the words “purchaser” and “manufacturer” occur in the text they should be taken to include representatives of the purchaser and manufacturer or inspectors mutually
45、agreed upon. NOTE 2While this standard is based on current Britishpractice which uses PCPVs in association with gas-cooled reactors, it is not intended to limit its use solely to reactors of this type. It is proposed to keep the standard under review, but it is realized that some of the requirements
46、 might be inapplicable to new developments and in such cases revised requirements should be specified by the purchaser. NOTE 3The titles of the publications referred to in this standard are listed on the inside back cover. NOTE 4Bibliographic references are identified by a letter and number in squar
47、e brackets,e.g. K4, and will be found either at the end of the relevant appendix or inAppendix N. 1.2 Definitions For the purposes of this British Standard the following definitions apply. 1.2.1 prestressed concrete pressure vessel (PCPV) a structure, enclosing a nuclear reactor, that contains the p
48、ressurized primary coolant during the operation of the plant 1.2.2 vessel structure the concrete vessel complete with tendons, anchorages and reinforcement, together with any integral part of the foundations 1.2.3 tendon a steel element, consisting of one or more wires, strands or bars, used to impa
49、rt prestress to the concrete 1.2.4 anchorage a mechanical device or assembly that retains theload in a stressed tendon and transmits it to theconcrete of the vessel structure 1.2.5 grip a component that secures the wire, strand or barwithin an anchorage 1.2.6 prestressing system an assembly of tendons and anchorages used to impart predetermined loads to the concrete 1.2.7 reinforcement steel elements consisting of wires, strands or bars contained within and bonded to the vessel concrete, but not used to impart prestress to the concrete 1.2.8 liner a membrane, sup
