This standard specifies the basic requirements and limits for nuclear criticality safety in the storage of fissile materials. This standard applies to the storage of fissile materials. GB 15146.3-1994 Nuclear criticality safety of fissile materials outside reactors Nuclear criticality safety requirements for storage of fissile materials GB15146.3-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Nuclear criticality safety for fissile materials outside reactor-Requirements for nuclear criticality safety in the storage of fissile material1Subject content and scope of application
This standard specifies the basic requirements and limits for nuclear criticality safety in the storage of fissile materials. This standard applies to the storage of fissile materials. 2 Reference standards
GB15146.3—94
GB15146.1 Nuclear criticality safety of fissile materials outside reactors Nuclear criticality safety administrative regulations GB15146.2 Nuclear criticality safety of fissile materials outside reactors Basic technical criteria and subcritical limits for the operation, processing and treatment of fissile materials
3 Terms
3.1 Storage unit (unit)
A collection of fissile materials treated as a whole. The material can be of any shape, and the material collection can also be composed of several separate small pieces.
3.2 Storage grid (grid cell)
A volume space in which the storage unit is placed and has a definite boundary. 3.3 Storage array
A regular arrangement consisting of several storage grid cells with storage units. 3.4 Verified calculation method
After comparison with experimental results, its reliability has been tested, and the scope of application and the calculation method of the deviation of the calculation results within this range have been determined.
4 Management requirements and technical standards
4.1 Management requirements
4.1.1 All operations of fissile materials in storage must comply with the relevant requirements of GB15146.1. 4.1.2 Approved storage control methods and operating rules must be written into written procedures; personnel involved in the transfer and storage of fissile materials must be familiar with these procedures, and storage limits must be posted. 4.1.3 Nuclear criticality safety management personnel must conduct necessary inspections to confirm that relevant personnel have implemented the established procedures. 4.1.4 Access to storage areas must be strictly controlled. 4.2 Technical Standards
4.2.1 In addition to complying with the requirements of GB15146.2, the storage of fissile materials must also comply with the requirements of 4.2.2 to 4.2.11. Approved by the State Administration of Technical Supervision on July 7, 1994 and implemented on January 1, 1995 bZxz.net
GB15146.3-94
4.2.2 Storage limits for fissile materials must be determined based on experimental data or results calculated using verified calculation methods. 4.2.3 Storage equipment and warehouse facilities must be designed, manufactured and maintained based on good engineering practice experience. 4.2.4 The design of warehouse facilities should exclude unreasonable storage layouts and structural forms, and minimize reliance on administrative management. 4.2.5 The storage of fissile materials must be able to avoid criticality accidents under conditions such as fire, water, earthquake and other natural hazards.
4.2.6 The stored fissile material units should be enclosed in certain containers, which should be watertight. The airtight condition can be relaxed only when it is certain that the container will not be flooded or that criticality will not be achieved even if water enters the container. 4.2.7 Birdcage-type fixtures, metal cans with lids, and solid barrier structures used on shelves can be used to maintain the spatial separation between solid fissile material units. The shelves must be strong and non-combustible. 4.2.8 It should be strived to ensure that there are no flammable items in the storage area. If the storage area cannot avoid the presence of a large amount of flammable items, such as flammable metal cutting fragments, a fire protection system must be installed. 4.2.9 In storage areas equipped with water spray systems, containers for fissile materials must be designed to prevent water accumulation. 4.2.10 In storage areas for solid fissile materials equipped with water spray systems, the possibility of nuclear criticality accidents under water accumulation conditions must be evaluated.
4.2.11 In storage places where nuclear criticality accident alarm systems are required to be installed, the installation of the alarm systems must comply with the provisions of relevant standards, and special attention should be paid to properly determining the installation location of the alarm system detectors. 4.2.12 Good warehouse management must be regarded as an important part of the actual work of nuclear criticality safety. 5 Purchase and storage limits and use conditions
5.1 In principle, there is no need to restrict the storage method of fissile materials when any of the following conditions are met: a. A uniform mixture or solution of water with a 235U enrichment of not more than 1.0wt%; b. Lump uranium metal or solid uranium compound with a 235U enrichment of not more than 5.0wt% and a ratio of the number of hydrogen atoms to the number of atoms of fissile material nuclides ≤0.5. These block materials are required to have no concave surfaces and the units are not composed of small strips or small blocks. This restriction can be cancelled when there is no hydrogen-containing medium in the container and the container is watertight; c. A uniform aqueous solution with a 235U concentration of not more than 11.7 g/L, or a Pu concentration of not more than 7.2 g/L, and the material can be guaranteed not to be accidentally concentrated and precipitated during storage;
d. The container contains a single nuclide unit of metallic 233U, 235U, 238U, 239Pu or 241Pu, or a unit composed of any combination of these nuclides, and the amount of fissile material contained in the unit is not more than 0.015 kg, and the minimum size of the packaging container is greater than 10 cm; e. A uniform mixture or aqueous solution of rings and natural uranium or depleted uranium, with the weight percentage of rings in (rings + uranium) not more than 0.13wt%.
5.2 For storage units of several common fissile materials, the unit limits can adopt the values ​​given in Table 1. The limits for Class 1 units in Table 1 refer to the limits when the packaging container of the unit is made of hydrogen-free materials (such as steel, aluminum, etc.) and the wall thickness does not exceed 1.27 cm; the limits for Class I units refer to the limits when the packaging container is made of steel, aluminum, etc. materials containing hydrogen or the wall thickness exceeds 1.27 cm. 5.3 The limits listed in Table 1 apply to various compositions of uranium (or cycloid) isotopes. However, all uranium isotopes other than uranium-238 should be regarded as uranium-235; all cycloid isotopes other than cycloid-240 should be regarded as cycloid-239. 5.4 The shapes of the units in Table 1 are generally not limited (but special considerations should be made for geometric shapes such as thin plates). For metal, compound or mixture units, except for the thin plastic (no more than 10g polyethylene per kilogram of fissile material) and sealing gaskets that wrap the material, there should generally be no other hydrogen-containing substances. If there are any, the atomic number ratio of hydrogen to fissile material nuclides should be calculated together with the material. 5.5 The limits listed in Table 1 should not be relaxed by various magnification factors applicable to isolated units. 5.6 The container containing the unit of fissile material shall be located at the center of the cell, and the deviation from the center of the cell shall not exceed 10% of the cell size. 5.7 When the units listed in Table 1 are arranged in an isolated straight line or plane array, when the distance between the unit centers is greater than 40cm and the distance between the unit container surfaces is greater than 30cm, the number of arranged units may be unlimited. 110
Unit type
【Class unit
1Class unit
GB 15146.3—94
Table 1 Unit limits for storage of fissile materialsMaterial type
Metal, compound or mixture (H/X1≤0.5)Metal, compound or mixture (0.5
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