Foreword
7.1.2 and 7.1.3 of this standard are recommendatory, and the rest are compulsory.
Fixed neutron absorbers are frequently used as part of the overall nuclear criticality control measures to ensure the subcritical safety margin required under normal and abnormal operating conditions, so that the facilities or equipment function more economically and effectively.
GB 15146.2-1994 Nuclear criticality safety for fissile materials outside reactor - Basic technical practices and subcritical limits for handling, processing and operations of fissile materials sets forth general requirements for nuclear criticality safety control with neutron absorbers. This standard supplements the relevant requirements in GB 15146.2-1994 and GB 15146.8-1994 Nuclear criticality safety for fissile materials outside reactors - Criticality safety criteria for the handling, storage, and transportation of LWR fuel unit outside reactors, and provides more detailed safety requirements for the use of fixed neutron absorbers in the design, construction and operation of non-reactor nuclear facilities. In this standard, the so-called fixed neutron absorber refers to the neutron absorber which is an integral part of the facility, equipment or fuel component and plays the role of nuclear criticality safety control as required.
This standard is prepared with reference to American national standard ANSI/ANS-8. 21-1995 Use of Fixed Neutron Absorbers in Nuclear Facilities Outside Reactors. Its technical content is equivalent to the latter, but necessary adjustments have been made in terms of the structure, and the normative references have been replaced by the corresponding standards of China.
This standard was proposed by China National Nuclear Corporation.
Drafting organization of this standard: Institute for Standardization of Nuclear Industry.
Chief drafter of this standard: Zhuo Fengguan.
Nuclear criticality safety for fissile materials outside reactors - Safety requirements for the use of fixed neutron absorbers
1 Scope
This standard provides guidance for the use of fixed neutron absorbers as an integral part of nuclear facilities and fissionable material process equipment outside reactors, where such absorbers provide nuclear criticality safety control.
This standard is applicable to the design, construction and operation of facilities for the operation, processing, treatment and storage of fissile materials. This standard is also applicable to equipment related to the transport of fissile materials.
2 Normative references
The following standards contain provisions which, through reference in this standard, constitute provisions of this standard. At the time of publication, all editions listed are valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.
GB 15146.1-1994 Nuclear criticality safety for fissile materials outside reactors - Administrative regulation for nuclear criticality safety
GB 15146.2-1994 Nuclear criticality safety for fissile materials outside reactors - Basic technical criteria and subcritical limits for handling, processing and operations of fissile materials
HAF 0400 (91) Safety specifications for quality assurance of nuclear power plant
3 Definitions
For the purposes of this standard, the following definitions apply.
3.1
nuclear criticality safety
prevention of nuclear criticality accidents and protection against the consequences thereof, preferably by prevention of inadvertent nuclear chain reaction
3.2
neutron absorber
neutron-capture material
3.3
fixed neutron absorber
neutron absorbers in solids with an established geometric relationship to the locations occupied by fissionable material
3.4
moderator
material that reduces the energy of neutrons by scattering them
3.5
fixed moderator
moderator with an established geometric relationship to the locations occupied by the fixed neutron absorber and fissionable material
3.6
neutron absorber system
any combination of fixed neutron absorbers, fixed moderators, and other materials with an assigned nuclear criticality safety function
3.7
benchmark experiment
experiment appropriate for the validation of calculational methods applicable to the evaluation of the neutron absorber system
3.8
validation
process of using experimental results to demonstrate that the analytical methods used to compute the effectiveness of the neutron absorber systems for criticality control meet predetermined requirements
3.9
verification
establishment or confirmation of the truth or accuracy of a fact by investigation, comparison with a standard, or reference to the facts
3.10
in-service verification
periodic verification of the integrity of the neutron absorber system subsequent to installation
Foreword i
1 Scope
2 Normative references
3 Definitions
4 General safety considerations
5 Design requirements
6 Safety evaluations
7 Verification and inspection
