NB/T 25043.1-2014Construction technology code for conventional island and BOP of nuclear power plant - Part 1: Civil work (English PDF)

Foreword

This document was issued on 29 June 2014 by the National Energy Administration of the PRC and takes effect on 1 November 2014.

It is a NB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

It is classified under ICS 27.010, Chinese classification F 01.

NB/T 25043, Construction technology code for conventional island and BOP of nuclear power plant, is divided into eight parts.

Part 1: Civil work.

Part 2: Turbine generator set.

Part 3: Circulating water system equipment.

Part 4: Thermal instrumentation and control devices.

Part 5: Water treatment and hydrogen production systems.

Part 6: Piping.

Part 7: Heating, ventilation and air conditioning.

Part 8: Thermal insulation and painting.

This document is Part 1 of NB/T 25043.

This part was drafted in accordance with the rules given in GB/T 1.1-2009, Directives for standardization - Part 1: Structure and drafting of standards.

This part was proposed by, and is under the jurisdiction of, the China Electricity Council.

The chief drafting organizations of this part are: China Nuclear Power Engineering Co., Ltd. (CGN Engineering Co., Ltd.) and Shenzhen China Nuclear Power Design Co., Ltd.

The participating drafting organizations of this part are: China Electric Power Construction Co., Ltd. (Nuclear Power Construction Branch of China Construction Second Engineering Bureau Co., Ltd.), the Second Electric Power Construction Company of Shandong Electric Power Construction Group of China Power Construction Group, the Second Electric Power Construction Company of Anhui of China Energy Engineering Group, and the State Nuclear Electric Power Planning Design and Research Institute.

The chief drafters of this part are: Wu Jianjun, Zhou Xiangqun, Wang Qining, Li Zheng, Ren Yongqing, Yang Fan, Li Fuguo, Ma Liang, Sun Xianli, Tang Hongbing, Song Chunxia, Xu Xixing, Zheng Fuxian, Liu Kehui, Liu Dong, Chang Haifeng, Wang Xueliang, Chen Huiming, Gong Tao, Guo Chaoyu and Nan Wei.

Comments and suggestions arising during the application of this standard should be sent to the Standardization Management Centre of the China Electricity Council, No. 1, Baiguang Road Ertiao, Beijing, postcode 100761.

Publication Data

Standard designation as printed on the cover: NB/T 25043.1-2014. The document belongs to the NB series, the Energy Industry Standards of the People's Republic of China (Zhonghua Renmin Gongheguo Nengyuan Hangye Biaozhun).

Chinese title: He dian chang chang gui dao ji fu zhu pei tao she shi jian she shi gong ji shu gui fan - Di 1 bu fen: Tu jian. English title as printed on the cover: Construction technology code for coventional island and BOP of nuclear power plant - Part 1: Civil work.

ICS classification: 27.010 (energy and heat transfer engineering in general). Chinese standard classification code (CCS): F 01.

Record number (beian hao) assigned on filing with the national authorities: 46505-2014.

Date of issue: 29 June 2014. Date of implementation: 1 November 2014.

Issuing body: National Energy Administration of the People's Republic of China (Guojia Nengyuan Ju).

The document has 65 numbered pages of technical text plus front matter numbered in Roman figures, and it contains three normative annexes, eleven clauses, five numbered tables in the opening chapters and further tables in the later chapters.

This is Part 1 of a multi-part standard. It is not a revision and it does not replace any earlier document; no superseded designation is printed on the cover.

Structure of the Document

The technical text is organized in eleven clauses followed by three normative annexes, and the clause structure reflects the sequence of civil construction on a nuclear power plant site.

Clauses 1 to 4 cover the scope, the normative references, the terms and definitions and the general principles; clause 5 sets out the basic requirements, covering construction qualification, process standards, quality control, quality assurance, construction organization design, materials, construction sequence and structural stability during construction, test results, design documents, construction defects, and construction safety management and site environmental protection.

Clause 6 covers excavation and backfilling, with subclauses on general requirements, excavation, blasting and backfilling, and it is supported by Annex A on the safety allowable criteria for blasting vibration and by Annex B on the empirical formula for the propagation law of particle vibration velocity.

Clause 7, the longest clause of the document, covers reinforced concrete structures, with subclauses on general requirements, materials, mix proportion and mixing, transport, placing and curing, formwork, reinforcement works, fabrication and installation of embedded parts, precast concrete members, and the construction of special structures.

Clause 8 covers steel structures, with subclauses on general requirements, fabrication of steel structures, erection of steel structures and coating of steel structures; it is supported by Annex C on the formula for calculating the shrinkage allowance of welding deformation.

Clause 9 covers masonry, with subclauses on basic requirements, quality requirements for masonry materials and construction process control.

Clause 10 covers architectural decoration, with subclauses on floor and ground works, plastering and facing tile bonding works, suspended ceiling works, painting and coating works, roofing works, door and window works, and plant area enclosure works.

Clause 11 covers tests and measurements, with subclauses on general requirements, raw material tests, and the testing of members (components) and of structural entities.

The three annexes are all normative: Annex A, safety allowable criteria for blasting vibration; Annex B, empirical formula for the propagation law of particle vibration velocity; Annex C, formula for calculating the shrinkage allowance of welding deformation.

1 Scope

NB/T 25043.1-2014 is Part 1 of the Chinese construction technology code for the conventional island and balance of plant of a nuclear power station, and it covers the civil work. That means the turbine building, the electrical and auxiliary buildings, the pump houses and the supporting structures outside the nuclear island - everything from the excavation to the finished architectural surfaces. The code sets the scope and the defined terms, the general requirements on construction organisation, quality management and the records to be kept, then works through the trades in turn. Earthworks come first, with excavation, dewatering, backfill and compaction. Concrete follows at length: formwork and its tolerances, reinforcement fixing and splicing, embedded parts and their positional accuracy, concrete mix, placing, compaction and curing, construction joints, mass concrete and its temperature control, and the surface finishes required. Steel structures are covered with their fabrication, erection, bolting, welding and inspection, then masonry, and then the architectural finishes - flooring, walls, ceilings, doors and windows, waterproofing and painting. Each item of work is given its construction requirements, its permitted deviations and the testing that verifies it. Note that the English title printed on the cover reads coventional for conventional, a typographic error in the original. The code applies to PWR stations built in China.

This part of NB/T 25043 specifies the technical requirements for the civil construction of the conventional island and of the balance of plant (hereinafter referred to as BOP) of nuclear power plants.

This part applies to the civil construction of the conventional island and of the balance of plant of domestic pressurized water reactor nuclear power plants; other nuclear power projects may apply it by reference.

This part does not apply to the civil construction of open drainage channels (tunnels), heavy-component wharves, plant-area bank revetments and similar structures of nuclear power plants, nor to the civil construction of reservoirs, roads and bridges.

The scope therefore covers, for the conventional island and BOP only, earthworks and backfilling, reinforced concrete structures, steel structures, masonry, architectural decoration and finishing, and the associated tests and measurements, as reflected in the clause structure of the document.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB 175, Common portland cement.

GB/T 700, Carbon structural steels.

GB/T 1228, High strength bolts with large hexagon head for steel structures.

GB/T 1229, High strength large hexagon nuts for steel structures.

GB/T 1230, High strength washers for steel structures.

GB/T 1231, Specifications of high strength bolts with large hexagon head, large hexagon nuts and washers for steel structures.

GB 1499.1, Steel for the reinforcement of concrete - Part 1: Hot rolled plain bars.

GB 1499.2, Steel for the reinforcement of concrete - Part 2: Hot rolled ribbed bars.

GB/T 1591, High strength low alloy structural steels.

GB/T 1596, Fly ash used for cement and concrete.

GB/T 1725, Paints, varnishes and plastics - Determination of non-volatile matter content.

GB/T 1747.2, Paints and varnishes - Determination of pigment content - Part 2: Ashing method.

GB/T 2975, Steel and steel products - Location and preparation of samples and test pieces for mechanical testing.

GB/T 3186, Paints, varnishes and raw materials for paints and varnishes - Sampling.

GB/T 3632, Sets of torshear type high strength bolt, hexagon nut and plain washer for steel structures.

GB/T 4842, Argon.

GB/T 5117, Covered electrodes for manual metal arc welding of non-alloy and fine grain steels.

GB/T 5118, Covered electrodes for manual metal arc welding of creep resisting steels.

GB/T 5210, Paints and varnishes - Pull-off test for adhesion.

GB/T 5293, Carbon steel electrodes and fluxes for submerged arc welding.

GB/T 5313, Steel plate with through-thickness characteristics.

GB/T 5780, Hexagon head bolts - Product grade C.

GB/T 5782, Hexagon head bolts.

GB 6566, Limits of radionuclides in building materials.

GB 6722, Safety regulations for blasting.

GB/T 6750, Paints and varnishes - Determination of density - Pyknometer method.

GB/T 7106, Graduations and test methods of air tightness, watertightness, wind load resistance performance for building external windows and doors.

GB 8076, Concrete admixtures.

GB/T 8110, Welding electrode wires for gas shielded arc welding of carbon and low alloy steels.

GB/T 8484, Graduation and test method of thermal insulating properties for building external windows and doors.

GB/T 8923, Preparation of steel substrates before application of paints - Visual assessment of surface cleanliness.

GB 9448, Safety in welding and cutting.

GB/T 10045, Carbon steel flux cored electrodes for arc welding.

GB/T 10433, Cheese head studs for arc stud welding.

GB/T 11263, Hot rolled H and cut T section steel.

GB/T 12470, Low alloy steel electrodes and fluxes for submerged arc welding.

GB/T 12755, Profiled steel sheets for buildings.

GB 13014, Remained heat treatment ribbed steel bars for the reinforcement of concrete.

GB/T 14685, Pebble and crushed stone for construction.

GB/T 14957, Steel wires for melt welding.

GB/T 17493, Low alloy steel flux cored electrodes for arc welding.

GB/T 18046, Ground granulated blast furnace slag used for cement and concrete.

GB/T 18736, Mineral admixtures for high strength and high performance concrete.

GB/T 19879, Steel plates for building structures.

GB/T 20491, Steel slag powder used for cement and concrete.

GB 50010, Code for design of concrete structures.

GB/T 50080, Standard for test method of performance on ordinary fresh concrete.

GB/T 50081, Standard for test method of mechanical properties of ordinary concrete.

GB 50108, Technical code for waterproofing of underground works.

GB 50119, Technical code for application of concrete admixtures.

GB 50141, Code for construction and acceptance of water and sewage works structures.

GB 50202, Code for acceptance of construction quality of building foundation.

GB 50203, Code for acceptance of constructional quality of masonry structures.

GB 50204, Code for acceptance of constructional quality of concrete structures.

GB 50205, Code for acceptance of construction quality of steel structures.

GB 50207, Code for acceptance of construction quality of roof.

GB 50208, Code for acceptance of construction quality of underground waterproof.

GB 50209, Code for acceptance of construction quality of building ground.

GB 50210, Code for acceptance of construction quality of building decoration.

GB 50212, Code for construction and acceptance of anticorrosive engineering of buildings.

GB 50303, Code for acceptance of construction quality of electrical installation in buildings.

GB 50345, Technical code for roof engineering.

GB/T 50448, Technical code for application of cementitious grout.

GB/T 50476, Code for durability design of concrete structures.

GB 50496, Code for construction of mass concrete.

GB 50515, Code for design of conductive and antistatic floors.

GB 50573, Code for construction and quality acceptance of hyperbolic cooling towers.

GB 50661, Code for welding of steel structures.

DL 5009.1, Safety working regulation of electric power construction - Part 1: Thermal power generation.

DL/T 742, Technical specification for plastic components of cooling towers.

HG/T 2537, Carbon dioxide for welding.

JB/T 10045.3, Thermal cutting - Quality and dimensional tolerances of gas cutting.

JC 474, Waterproofing agents for mortar and concrete.

JC/T 479, Building quicklime.

JC/T 480, Building quicklime powder.

JG/T 164, Plasticizer for masonry mortar.

JG/T 226, Formed steel bars for concrete structures.

JGJ 8, Code for deformation measurement of building and structure.

JGJ/T 10, Technical specification for construction of concrete pumping.

JGJ 18, Specification for welding and acceptance of reinforcing steel bars.

JGJ 33, Technical code for safety of construction machinery in building engineering.

JGJ 52, Standard for technical requirements and test method of sand and crushed stone (or gravel) for ordinary concrete.

JGJ 55, Specification for mix proportion design of ordinary concrete.

JGJ 63, Standard of water for concrete.

JGJ 74, Technical specification for large formwork in building engineering.

JGJ 81, Technical specification for welding of steel structures of buildings.

JGJ 82, Technical specification for high strength bolt connections of steel structures.

JGJ 96, Technical specification for steel-framed plywood formwork.

JGJ/T 98, Specification for mix proportion design of masonry mortar.

JGJ/T 104, Specification for winter construction of building engineering.

JGJ 107, Technical specification for mechanical splicing of steel reinforcing bars.

JGJ 120, Technical specification for retaining and protection of building foundation excavations.

JGJ 126, Specification for construction and acceptance of exterior wall facing tiles.

JGJ 130, Technical code for safety of steel tubular scaffold with couplers in construction.

JGJ 162, Technical code for safety of forms in construction.

JGJ 166, Technical code for safety of bowl-buckle steel tubular scaffold in construction.

NB/T 20117, Regulations on construction safety management of nuclear power engineering.

NB/T 20119, Regulations on construction item management of nuclear power engineering.

NB/T 20123, Regulations on the division of divisional and subdivisional works of nuclear power engineering.

NB/T 20125, Technical specification for grouting construction of foundations of safety important equipment of pressurized water reactor nuclear power plants.

NB/T 20127, Technical requirements for fabrication and installation of embedded parts of pressurized water reactor nuclear power plants.

NB/T 25044.1, Specification for quality acceptance of construction of conventional island and BOP of nuclear power plant - Part 1: Civil work.

YB 3301, Welded H section steel.

YB/T 4155, Hot rolled carbon steel round bars and wire rods for standard parts.

HAF 003, Safety regulations for quality assurance of nuclear power plants.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1 conventional island. The whole of the turbine generator set of a nuclear power plant together with its supporting facilities and the related buildings and structures.

3.2 balance of plant (abbreviated BOP). The whole of all supporting equipment, facilities, buildings and structures of a nuclear power plant other than those of the nuclear island and of the conventional island.

3.3 nuclear safety. The achievement of correct operating conditions, the prevention of accidents or the mitigation of accident consequences, so as to protect the personnel of the plant area, the public and the environment from undue radiation hazard.

3.4 item. A general designation covering materials, parts, components, systems, structures and computer software.

3.5 safety related important item. An item that forms part of a given safety group and whose failure or malfunction would affect another train or system.

3.6 non-safety related important item. An item that is not directly related to nuclear safety but whose failure would directly or indirectly impair the achievement of a safety function, or whose failure or malfunction would affect the availability of the plant.

3.7 book of technical specification. A written provision that states the requirements that a product, a service, a material or a process must satisfy, and that indicates the procedure by which it is determined whether those stated requirements have been met.

3.8 operating unit. The organization that holds the licence (permit) issued by the national nuclear safety authority and that is responsible for the management and operation of the nuclear power plant.

3.9 empoloyer (employer). In this part, specifically the operating unit or the management organization that it entrusts and that is set up for the purpose of implementing the construction of the nuclear power plant project, such as an engineering company with independent legal personality; where authorized by contract, and within the limits of that contractual authorization, it may also be the supervision organization entrusted by the operating unit.

3.10 contractor. Apart from the employer and the organization it entrusts, the participating companies or units that undertake the tasks of construction of the nuclear power project, including design, supply, service and construction tasks; in this part the term may specifically designate the company or unit undertaking the construction work.

3.11 quality assurance. The planned and systematic set of activities necessary to provide adequate confidence that an item or a service will comply with the specified quality requirements.

3.12 quality assurance programme. The integration of all the specified and performed activities for the purpose of assuring quality, providing the technical activities for items and services and the related management control.

3.13 quality plan (QP). A schedule that identifies the operations, controls and records to be executed in the normal process sequence during the work period.

3.14 execution tracing file (ETF). The tracing record document used to record the control activities carried out by the civil works contractor on buildings or structures during the construction process; it is the tracing record of the control process of the physical construction of the works.

3.15 deep foundation pit. A foundation pit work with an excavation depth exceeding 5 m (5 m included), or a pit whose depth does not exceed 5 m but whose geological conditions, surrounding environment and underground pipelines are particularly complex.

3.16 special structures. Within the structures of the conventional island and BOP works, structures whose function is special and whose form is comparatively complex, such as the special-shaped table-top structure of the turbine generator or the inlet and outlet water culverts.

4 General principles

4.1 This part is established in order to regulate the civil construction of the conventional island and BOP of nuclear power plants, to assure construction quality, and to achieve technical advancement, safe applicability and economic rationality.

4.2 The construction of the conventional island and BOP of nuclear power plants shall adhere to the basic principle of quality first and safety first. The contractor shall have complete quality, safety, health and environmental management systems, and these shall be documented. The occupational health, safety and environmental protection matters involved in the construction shall comply with the provisions of the relevant national standards in force.

4.3 New technologies, new processes and new materials shall be actively adopted in construction. New technologies, new processes and new materials shall have undergone testing and appraisal, and a dedicated scheme shall be prepared and subjected to expert justification before they may be used.

4.4 In addition to complying with the provisions of this part, the construction of the conventional island and BOP of nuclear power plants shall conform to the design requirements and shall observe the provisions of the relevant national standards in force.

4.5 Construction in the rainy season and in winter shall further observe the provisions of the relevant national standards in force.

5 Basic requirements

5.1 Construction qualification. The contractor for the construction of the conventional island and BOP of a nuclear power plant shall hold the prescribed construction qualification.

5.2 Process standards. Unless otherwise stated, all materials and processes shall comply with the national and industry standards in force; the contractor shall construct in accordance with the technical requirements of the design documents, and shall comply with the relevant provisions of NB/T 25044.1.

5.3.1 The contractor shall establish quality assurance, technical management and quality control systems in accordance with the quality assurance programme.

5.3.2 Before the start of work the contractor shall prepare the quality plan (QP), the execution tracing file plan (ETF) or the inspection and test plan (ITP); shall set quality control points and quality inspection criteria for key locations, critical processes and concealed work locations; and shall submit these to the employer for review and approval. The employer may set control points in the QP, ETF or ITP documents on the basis of the quality supervision guideline. The QP, ETF plan or ITP document may be used in construction only after it has been approved by the employer.

5.3.3 The contractor shall prepare dedicated construction tracing records and inspection acceptance forms; after these have been checked and found acceptable, level by level, by the internal quality inspection personnel, the contractor shall notify the relevant personnel of the employer in advance to come to the site for inspection and verification.

5.3.4 Among the control points that have been set, for a witness point (W point), if the relevant personnel of the employer do not carry out the on-site verification on time, the contractor may continue with the next construction process; for a hold point (H point), if the relevant personnel of the employer have not signed their acceptance, the contractor shall not continue with the next construction process.

5.4.1 The quality assurance and management control of the procurement of engineering materials and components and of the construction shall comply with the quality assurance requirements, quality grade requirements and the requirements of the relevant design and construction codes stipulated in the contracting contract.

5.4.2 The designer of the nuclear power plant shall classify the items of the nuclear power plant and shall prepare a classification list of the items of the nuclear power plant. This list shall cover all the systems of the plant and shall state, for each principal component and structure, the safety class, the seismic category, the quality assurance class and the code class, or the standards and codes applied.

5.4.3 The contractor shall adopt the corresponding quality assurance activities on the basis of the safety class and the quality assurance class of the items and services.

5.4.4 For safety related important items, non-safety related important items, or items of quality assurance class QA, HAF 003 shall additionally be applied; a quality assurance programme and programme procedures shall be established, and they shall satisfy the requirements of the contract and of the other procurement documents.

5.5.1 The contractor shall prepare the construction organization design and the construction schemes before the start of work, and shall submit them to the employer for review and approval.

5.5.2 The preparation of the construction organization design shall follow the construction procedure of the project and shall comply with the following principles: a) it shall satisfy the requirements of the construction contract or of the tender documents as regards quality, project schedule, safety, technology, environmental protection and cost; b) where new technologies, new processes, new materials and new equipment are adopted, they shall have appraisal evidence and shall be verified by testing where necessary; c) it shall adhere to a scientific construction procedure and a rational construction process, achieving technical advancement, rational deployment and mature processes, with contents that are specific, directive and workable; d) the feasibility of large construction schemes shall undergo preliminary justification and shall be refined at the implementation stage; e) it shall be effectively integrated with the three management systems of quality, environment and occupational health and safety.

5.5.3 The main bases for the preparation of the construction organization design include the following contents: a) the laws, regulations, codes, rules and standards of the State, of the locality and of the industry; b) the tender documents and the contract documents of the works; c) the technical standards, installation procedures, quality assurance programme and programme procedures, safety, health and environmental management provisions and other documents supplied by the employer; d) the site conditions of the works, the engineering geology and hydrology, the meteorological conditions and other natural conditions; e) the supply situation of the resources relating to the works; f) the production capacity, the condition of the machinery and equipment and the technical level of the enterprise.

5.5.4 The contents of the construction organization design shall cover the whole process of the project, including the basis of preparation, the general description of the works, the construction organization structure, the allocation and training management of human resources, the site layout plan, the deployment of construction, the management of machinery and tools, the management of materials, the construction progress plan, the construction preparation and resource allocation plan, the principal construction methods and the special construction measures, the principal construction management plans, quality assurance and control, safety, occupational health and environmental management, documentation and information management, interface management and other basic contents.

5.6.1 Building materials, components and equipment shall be inspected in accordance with the design requirements, the construction technical standards and the contract stipulations; those that have not been inspected or that have failed inspection shall not be used in the works.

5.6.2 Before placing the order for materials, the contractor shall submit in advance the material submittal together with the supplier qualification, the technical evaluation report, the attachments and other documents for the review and approval of the employer; where necessary an on-site assessment of the source of supply shall be provided. Before the materials arrive on site, the contractor shall submit in advance the arrival acceptance form of the construction materials, together with the ex-works quality certificates, delivery notes, ex-works quality conformity certificates, test reports and similar documents, and shall notify the employer to carry out the arrival acceptance. Where, according to the standards and codes, the design documents and the requirements of the technical specification, acceptance tests are to be carried out when the materials arrive on site, the contractor shall carry out the tests as required and shall supply the test results.

5.6.3 The contractor shall state clearly in its management system the requirements for the site management of materials, and shall carry out, as prescribed, the classified storage, safekeeping and identification of the materials.

5.7.1 The civil construction processes and sequence shall comply with the requirements of the design structural system and with the needs of equipment installation.

5.7.2 The contractor shall be responsible for assuring the structural stability of the works at each construction stage.

5.7.3 During installation, measures shall be taken as required to assure sufficient stability of the structure and sufficient strength of the joints.

5.7.4 Where loads not considered in the design (such as lifting loads, guy ropes, stacking of equipment and similar) are to be applied to a building or structure under construction, a check calculation shall be carried out, and the work may be implemented only with the agreement of the design party.

5.8.1 All the tests prescribed in the text of this part, all the acceptance tests carried out on materials before use, and the verification tests carried out during use, shall have all their test results submitted to the employer.

5.8.2 For test cubes, test specimens and related materials concerning structural safety, the employer shall be notified to witness the sampling, and the samples shall be sent to a qualified quality testing unit approved by the employer for testing.

5.9.1 The design documents used in this part are generally the design drawings, specifications, books of technical specification and design changes (change orders) provided by the employer.

5.9.2 Where the contractor has doubts about the design documents, or finds errors in them, or finds them difficult to implement in construction, it shall promptly raise a clarification request or a field change request with the employer and the design unit.

5.10.1 For defects arising in construction or installation, the contractor shall promptly take measures to mitigate the consequences caused by the nonconformity; the nonconforming item shall be marked and segregated on site; the causes shall be carefully investigated and analysed; in accordance with the provisions of the nonconformity management procedure, the appraisal and classification shall be carried out, the nonconformity report and the disposition scheme or recommendation shall be drawn up and submitted to the employer for review and approval, and the approved disposition scheme or the reply opinion shall be implemented. The contractor shall file all the quality records and acceptance documents formed during the implementation of the scheme, and after completion of the implementation shall apply as prescribed for the employer to inspect and confirm the closure of the nonconformity.

5.10.2 Where a nonconformity arising during construction or installation causes an accident, the reporting and handling shall be carried out strictly in accordance with the relevant national provisions.

5.11.1 The contractor shall discharge the corresponding safety responsibilities prescribed by the national laws and regulations concerning work safety, shall establish and implement a comprehensive safety management system, shall continuously observe and improve the safety culture, and shall place safety in the foremost position of construction project management.

5.11.2 The contractor shall, in accordance with the national or local environmental protection laws and regulations, establish an environmental management system for the construction site, shall assure that the pollutant discharges during the construction period comply with the relevant national discharge standards, and shall, within the safe construction organization measures or the dedicated schemes, formulate effective schemes and measures for the prevention of pollution and the improvement of environmental sanitation.

5.11.3 In addition to complying with the provisions of 4.2 of this part, the civil construction of the conventional island and BOP of nuclear power plants shall comply with the relevant provisions of NB/T 20117 and DL 5009.1 as well as with those of the project safety, health and environmental management.

6 Excavation and backfilling

6.1.1 Before the start of work, the contractor shall obtain the design documents relating to the excavation, the as-built drawings of the existing surrounding underground pipe networks and of the existing buildings and structures, and the engineering geology and hydrogeology data. During construction, attention shall be paid to the protection of underground galleries, pipelines and other underground facilities.

6.1.2 The employer shall supply the contractor with the plane control stakes and the levelling points, which serve as the basis for construction survey, setting out and acceptance of the works. The contractor shall first set out from these points, and may start work only after the setting out has been checked and found acceptable.

6.1.3 Before the start of work, the contractor shall prepare a dedicated construction scheme and submit it to the employer for review. The dedicated construction scheme shall include the excavation of the foundation pit (trench), the blasting of the rock foundation and the construction methods for the support of the foundation pit (trench). The support design of a deep foundation pit shall be carried out by a unit holding the corresponding qualification, and the dedicated construction scheme for the support of a deep foundation pit shall undergo expert justification review in accordance with the relevant national provisions.

6.1.4 Before construction, the planning and construction of the temporary drainage system within the construction area shall be carried out, and attention shall be paid to its compatibility with the drainage system of the plant area. The temporary drainage facilities shall as far as possible be combined with the permanent drainage facilities.

6.1.5 During construction, the accumulated water of the site and of the foundation pit (trench) shall be promptly discharged, so that the excavation area is kept in a dry construction environment. In addition to satisfying the discharge of all infiltrating groundwater or seawater, the capacity of the pumps of the drainage system shall also satisfy the need for the timely discharge of storm water.

6.1.6 Where, during construction, the geological conditions are found not to conform to the original investigation and design requirements, the contractor shall promptly report to the employer, which shall organize the design, investigation, supervision and contractor parties to jointly determine the treatment measures.

6.1.7 On the basis of the climatic conditions, of the geological conditions of the foundation pit (trench) and of the slopes, and of the construction method, effective support measures and safety measures for the foundation pit (trench) and for the slopes shall be adopted, so as to assure the safety of the foundation pit (trench), of the slopes and of the personnel.

6.1.8 Excavation and backfilling construction shall further observe the provisions of the relevant national standards in force.

6.2.1 Excavation shall adopt a construction method proceeding from the top downwards; an excavation method that proceeds from the bottom upwards and produces overhanging rock masses or soil masses shall not be adopted.

6.2.2 The sequence and the methods of earthwork excavation shall be consistent with the design working conditions, and shall follow the principle of supporting the trench as it is opened, bracing first and excavating afterwards, excavating in layers, and strictly prohibiting over-excavation.

6.2.3 The excavation of the designed rock slope profile shall adopt pre-splitting blasting or smooth blasting methods.

6.2.4 The excavation of the foundation rock should adopt a layered bench blasting method.

6.2.5 Before the excavation of the designed slope, the clearing of dangerous rock outside the excavation line, the trimming of the slope, the reinforcement, the drainage and similar works shall be well carried out.

6.2.6 The slope values of the temporary earthwork excavation during construction shall comply with the design requirements; where there is no design requirement, they shall comply with the provisions of the relevant national standards in force.

6.2.7 Where, during the excavation process, geological conditions unfavourable to the stability of the slope are encountered, the contractor shall promptly notify the employer to organize the investigation, design, construction and supervision units and other relevant units to coordinate jointly and to propose the corresponding solution methods.

6.2.8 For locations with special requirements, the corresponding excavation methods shall be determined separately.

6.2.9 The excavated earth and rock shall be promptly transported away and shall not be stacked in a disorderly manner around the foundation pit or the slopes.

6.2.10 After the excavation of the foundation pit (trench), the foundation pit (trench) and the slopes shall be promptly inspected and treated, so as to assure that all loose blocks and floating soil have been removed. The support of the foundation pit (trench) shall comply with the design documents and with the provisions of GB 50202 and JGJ 120.

6.2.11 After the excavation of the foundation pit (trench) has been completed, the contractor shall promptly notify the employer to organize the investigation, design, construction, supervision and other relevant units to carry out the acceptance.

6.2.12 The acceptance of the earthwork of the foundation pit (trench) shall be premised on the safety of the supporting structure and on the safety of the surrounding environment. Where the design gives index values, the design requirements shall be the basis; where the design gives no index values, the provisions of GB 50202 shall be applied.

6.2.13 For the foundation pits of buildings and structures for which geological mapping is required, the geological mapping work shall be completed before the acceptance by the investigation unit entrusted by the employer.

6.2.14 The permissible deviations of the excavation quality of the designed foundation surface and of the slope profile shall satisfy the following requirements: a) the elevation of the excavation of the designed foundation base shall satisfy the design requirements and there shall be no under-excavation; in the case of blasting excavation, the over-excavation shall not be greater than 20 cm; b) the overall average slope of the excavated slope shall comply with the design requirements; the excavation deviation of each bench shall be 2 percent of its excavation height and shall not be biased to one side; c) the length and the width of the blasting excavation shall satisfy the design requirements, there shall be no under-excavation, and the extent beyond the design line shall not be greater than 15 cm; d) for the other items not prescribed here, the relevant requirements of GB 50202 shall be satisfied.

6.3.1 The safety-related requirements of blasting operations shall observe the relevant provisions of GB 6722.

6.3.2 Before the blasting construction, the contractor shall carry out the blasting design and shall report it to the competent authority for approval. The drilling and blasting construction shall be carried out in accordance with the blasting design requirements.

6.3.3 Before the blasting construction, blasting trials shall be carried out so as to obtain rational blasting parameters to guide the blasting construction.

6.3.4 Immediately adjacent to the horizontal foundation surface, a protective layer should be reserved. The thickness of the reserved protective layer shall be determined by the blasting trials.

6.3.5 The effect of pre-splitting blasting and of smooth blasting shall comply with the following requirements: a) the fracture surface formed by the pre-splitting blasting shall be continuous; b) on the surface of the excavation profile, the traces of the remaining blast holes shall be uniformly distributed; the preservation rate of the traces of the remaining blast holes shall reach 80 percent or more for rock masses with undeveloped jointing, shall reach 80 percent to 30 percent for rock masses with relatively developed joints and fissures, and shall reach 30 percent to 10 percent for rock masses with extremely developed joints and fissures; c) the unevenness of the rock surface between adjacent blast holes shall not be greater than 15 cm; d) the walls of the remaining blast holes shall not show obvious blasting cracks.

6.3.6 The effect of bench blasting shall satisfy the following requirements: a) the fragment size of the blasted muck and the muck pile shall be suitable for the operation of the excavating machinery; if the blasted muck is to be used, its block size shall further comply with the relevant requirements; b) the bottom of the blasting area shall have few remaining root humps and few flying rocks from the blasting.

6.3.7 Where blasting has to be carried out in the vicinity of newly placed concrete or of completed buildings and structures, the following provisions shall be complied with: a) the blasting vibration parameters at the newly placed concrete and at the completed buildings and structures shall not be greater than the safety permissible values; the safety permissible criteria for blasting vibration are given in Annex A; b) during drilling and blasting construction, the blasting vibration may be forecast and controlled in accordance with the empirical formula of Annex B.

6.3.8 During the blasting construction, blasting safety monitoring shall be carried out. The blasting safety monitoring shall be entrusted by the employer to an independent third party.

6.3.9 Blasting safety monitoring shall follow the following principles: a) before the blasting construction a blasting safety monitoring scheme shall be prepared; the monitoring items and the layout of the measuring points shall be planned in an integrated manner on the basis of the safety requirements of the blasting works and of their environment; b) the various blasting safety monitoring items should be monitored simultaneously; c) the selection of the monitoring instruments and equipment shall satisfy the safety monitoring requirements; d) the records of the safety monitoring during the construction period shall be properly kept, and after each blast a monitoring briefing shall be promptly issued to guide the blasting construction; e) where abnormal conditions are found during the monitoring, they shall be promptly reported to the employer for treatment.

6.4.1 Before backfilling, the rubbish, tree roots and other sundries as well as the accumulated water and the silt of the backfilling area shall be cleared away.

6.4.2 The backfilling material shall be prepared in accordance with the design requirements, and may be used only after it has passed the acceptance inspection.

6.4.3 Before backfilling construction, the compaction plant shall be rationally selected on the basis of the characteristics of the works, the type of fill material, the design compaction coefficient, the construction conditions and similar factors.

6.4.4 The construction method of backfilling, the thickness of each backfilled layer, the number of compaction passes for each layer and similar parameters shall be determined by trials.

6.4.5 During the backfilling construction, the drainage measures as well as the compacted thickness, the moisture content control and the degree of compaction of each filled layer shall be inspected, and the upper layer may be placed only after the design requirements have been satisfied.

6.4.6 After the completion of the backfilling construction, the elevation, the slope gradient, the compaction coefficient and similar parameters shall be inspected; the inspection criteria shall comply with the provisions of Table 1, Quality inspection criteria for backfilling works, which distinguishes dominant items (elevation, layer compaction coefficient, slope) from general items (backfill material, layer thickness and moisture content, surface evenness) and gives, for each of them, the permissible deviations in millimetres for foundation pits and trenches, for site levelling by manual and by mechanical means, for pipe trenches and for ground (road) foundation courses, together with the corresponding inspection method.

7 Reinforced concrete structures

7.1.1 The division of concrete structure works shall comply with the provisions of NB/T 20123.

7.1.2 Before the start of work, the contractor shall submit to the employer detailed data on the various materials that it proposes to use in the concrete, including the names of the manufacturers and the sources of supply. The cement and the other materials used for exposed concrete shall be supplied by the same manufacturer or from the same source, and the materials shall not be changed without the agreement of the employer.

7.1.3 The arrival acceptance of building materials shall be carried out with reference to NB/T 20119.

7.1.4 The winter construction of concrete shall comply with the design documents and with the provisions of JGJ/T 104.

7.2.1.1 The cement shall comply with the requirements of the design documents and of GB 175.

7.2.1.2 Cements other than ordinary portland cement (P.O) are referred to in this part as other cements; the procedure for the use of other cements shall be approved by the employer. For other cements proposed on account of an engineering change, the contractor shall demonstrate by testing that they can improve the properties of the concrete and that they have no additional adverse effect.

7.2.1.3 The cement shall have a certificate of conformity issued by the manufacturer meeting the requirements of the relevant standards.

7.2.1.4 Where there is doubt about the quality of the cement, or where more than three months have elapsed since the cement left the works (more than one month for rapid hardening portland cement), it shall be retested before use and the decision whether it may still be used shall be taken on the basis of the test results.

7.2.1.5 The cement delivered into storage shall be of recent manufacture; the cement delivered shall be packed in sealed waterproof bags or carried in bulk cement transport vehicles; the bulk cement transport vehicles shall be designed for that purpose and shall be approved by the employer. Each batch of bagged cement shall be stored separately, and the cement shall be used in the order of delivery. During transport and during storage on the construction site, measures shall be taken to prevent the deterioration of the cement.

7.2.2 Admixture materials. The properties of the admixture materials shall comply with the provisions of the design documents and of the relevant national standards in force.

7.2.3 Mixing water. The water used to mix concrete, mortar and neat cement paste, as well as the water used to wash the aggregates, should be drinking water for domestic use, and the content of chlorides in the mixing water shall comply with the requirements of the overall concrete standard; seawater shall not be used. In addition to satisfying the above requirements, the mixing water shall further comply with the provisions of JGJ 63.

7.2.4 Coarse and fine aggregates. The coarse and fine aggregates used for the concrete shall comply with the provisions of the design documents and of JGJ 52 and GB/T 14685; sea sand and aggregates contaminated by seawater shall not be used.

7.2.5.1 The compatibility of the concrete admixture with the cement used shall be verified, and the admixture may be used only after the requirements have been satisfied.

7.2.5.2 When a concrete admixture is used in the process of mixing the concrete, its dosage shall comply with the provisions of the relevant standards and of the product instructions.

7.2.5.3 The dosage of the admixture shall be expressed as a percentage of the total mass of the cementitious materials; the weighing error shall comply with the provisions of the design documents and of the relevant standards.

7.2.5.4 The type of admixture shall be selected on the basis of the engineering design and of the construction requirements, and shall be determined through testing and technical and economic comparison. The admixture shall control the alkali content that it introduces into the concrete. Chloride-containing admixtures and other admixtures that are not environmentally friendly or that are harmful to the reinforcement or to the concrete shall not be used.

7.2.5.5 When trial mixes of admixture-bearing concrete are prepared, the raw materials, the mix proportions and the ambient conditions shall be the same as those actually used in the works; the test items shall be determined on the basis of the design documents and of the construction requirements, such as slump, change of slump with time, setting time, strength, air content, shrinkage and expansion; when the raw materials used in the works, the performance requirements of the concrete or the ambient conditions change, trial mixing shall be carried out again.

7.2.5.6 When admixtures of different types are used in combination, attention shall be paid to the influence of their compatibility on the properties of the concrete; tests shall be carried out before use, and the combination may be used only after the requirements of the works have been satisfied.

7.2.5.7 In addition to satisfying the above requirements, the production and use of concrete containing admixtures shall further comply with the design documents and with the provisions of GB 8076, GB 50119 and JC 474.

7.2.6.1 The alkali-aggregate reaction, the delayed ettringite formation and the dissolution of the concrete by soft water that may occur in the concrete shall be taken into account; the alkali content per unit volume of concrete (water-soluble alkali, expressed as sodium oxide equivalent) shall satisfy the following requirements: a) for concrete members with non-reactive aggregates and in a dry environment, the alkali content shall not exceed 3.5 kg for each cubic metre; where the design service life is 100 years, the alkali content of the concrete shall not exceed 3 kg for each cubic metre; b) for concrete structural members with non-reactive aggregates but in a humid environment (relative humidity not less than 75 percent), the alkali content shall not exceed 3 kg for each cubic metre; c) for concrete structural members with reactive aggregates and in a humid environment (relative humidity not less than 75 percent), the alkali content of the concrete shall be strictly controlled and mineral admixtures shall be added.

7.2.6.2 The maximum limit of the chloride ion content in the fresh concrete mix shall comply with the provisions of Table 2, Maximum limits of chloride ion content in the concrete mix (water-soluble value), expressed as a percentage; the table gives the limits for reinforced concrete and for prestressed concrete according to the environmental action grade, namely 0.3 for grade I-A, 0.2 for grade I-B, 0.15 for grade I-C, 0.1 for grades III-C, III-D, III-E and III-F, 0.1 for grades IV-C, IV-D and IV-E, and 0.15 for grades V-C, V-D and V-E, with a single limit of 0.06 for prestressed concrete; the note to the table states that the environmental action grades are to be taken with reference to GB/T 50476.

7.2.6.3 Under special conditions such as a freeze-thaw environment, a chloride environment or a chemical corrosion environment, the requirements for the selection of the raw materials of the concrete shall comply with the provisions of GB/T 50476.

7.2.7 Grouting materials. The performance requirements of cement-based grouting materials shall comply with the design documents and with the provisions of GB/T 50448.

7.3.1 Mix proportion design. The mix proportion design shall be carried out on the basis of the strength grade of the concrete and of the slump index required by the construction, and shall comply with the provisions of JGJ 55. Where the concrete has other technical performance requirements, besides taking them into account in the trial mixing process, the corresponding test items shall be added and confirmed by testing.

7.3.2.1 Trial mixing. The water-binder ratio shall be calculated in accordance with the materials and the mixing method actually used in the works; the water-binder ratio should be kept unchanged, and the properties of the fresh concrete shall be made to comply with the design and construction requirements by adjusting the mix proportion and the other parameters; the calculated mix proportion shall then be corrected and the trial mix proportion shall be proposed. The quantity of the concrete trial mix shall not be less than the provisions of Table 3; where mechanical mixing is used, the batch quantity shall not be less than one quarter of the rated mixing capacity of the mixer and shall not be greater than the nominal capacity (rated mixing capacity) of the mixer. Table 3, Minimum mixing quantity for concrete trial mixes, gives a quantity of 15 L for a maximum aggregate particle size of 31.5 mm and of 25 L for a maximum aggregate particle size of 40 mm.

7.3.2.2 Preparation of concrete strength test cubes. At least three different mix proportions shall be used for the concrete strength test cubes, taking the trial mix proportion as the reference and increasing and decreasing by 5 percent respectively the water-binder ratio of the other two mix proportions; their water content shall be the same as that of the trial mix proportion, while the sand ratio may be increased and decreased by 1 percent respectively. When the concrete strength test cubes are prepared, the slump, cohesiveness, water retention and apparent density of the fresh concrete shall also be measured, and taken as representative of the various basic properties of the fresh concrete of that mix proportion. For each mix proportion at least one group (three cubes) of specimens shall be prepared; after standard curing for 28 days they shall be tested in compression, so as to obtain the standard value of the cube compressive strength of that group.

7.3.3 Performance tests of the fresh concrete. The performance tests of the fresh concrete include the inspection and evaluation of the workability (slump or Vebe consistency), the bleeding test and the setting time determination; the various tests shall comply with the requirements of GB/T 50080.

7.3.4 Performance tests of concrete cube specimens. The cube specimens used for the compression test shall be made of concrete taken from the mixer or at the placing point; the cube compressive strength test and the axial compressive strength test of the concrete shall be carried out in accordance with the requirements of GB/T 50081.

7.3.5.1.1 The mixing time of the concrete shall be determined by testing on the basis of the slump, of the power curve of the mixer, of the capacity and of similar factors.

7.3.5.1.2 Before the next batch of materials is charged into the mixing drum, all the materials in the drum shall be discharged; when work is stopped, the mixer and all the charging and discharging equipment shall be washed clean with water.

7.3.5.2.1 Where mechanical mixing is used for the concrete, the mixing quantity shall not be less than one third of the rated mixing capacity of the mixer.

7.3.5.2.2 The permissible deviations of the batching of the raw materials of each batch of concrete shall comply with the provisions of Table 4, Permissible deviations of the batching of the various raw materials, which gives a permissible batching deviation, in percent by mass, of plus or minus 2 for cementitious materials, plus or minus 3 for coarse and fine aggregates, plus or minus 2 for mixing water and plus or minus 2 for admixtures.

7.3.6 Preparation and mixing of grouting materials. In addition to complying with the design documents and with the provisions of GB/T 50448, the preparation and mixing of cement-based grouting slurry shall further satisfy the relevant requirements of the material instructions.

7.3.7 Mix proportion design and mixing of mortar. The mix proportion design and the mixing of mortar shall comply with the design documents and with the provisions of JGJ/T 98.

7.3.8.1 Batching of admixtures. Admixtures shall not be poured directly into the cement.

7.3.8.2 For concrete for which the design has requirements as regards air content, the air content shall be tested on site during construction.

7.4.1.1 Concrete transport. Water shall not be added during the transport, conveying and placing of the concrete; concrete spilt during the transport, conveying and placing shall not be used for structural placing.

7.4.1.2 The freshly mixed concrete shall be delivered to the placing point in a completely mixed and homogeneous condition, so as to assure the uniformity and consistency between batches. The elapsed time of the fresh concrete from discharge out of the mixer to the completion of placing should not exceed the provisions of Table 5, and in hot, cold or dry weather it may be determined on the basis of the actual site conditions. The concrete shall be transported from the mixing point to the placing point with the fewest possible transfers and in the shortest possible time. Table 5, Elapsed time of the fresh concrete from discharge out of the mixer to the completion of placing, expressed in minutes, gives 150 min at an air temperature not exceeding 25 degrees Celsius and 120 min above 25 degrees Celsius for a ready-mixed concrete batching plant, 120 min and 90 min respectively for the construction site, and 90 min and 60 min respectively for a concrete products factory.

7.4.1.3 During the whole process from the discharge of the concrete out of the mixer to its delivery to the placing site, contamination by foreign matter, pollution, segregation and loss of mix constituents shall be prevented.