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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 12727-2002 Nuclear power plants—Electrical equipment of the safety system—Qualification, with respect to which, the following main technical changes have been made:
——The scope is modified (see Clause 1 of this standard; Clause 1 of Edition 2002);
——The normative references are modified (see Clause 2 of this standard; Clause 2 of Edition 2002);
——The terms and definitions are modified (see Clause 3 of this standard; Clause 3 of Edition 2002);
——The requirements are added for qualification objective, qualified life and qualified condition, qualification elements, qualification documentation, etc. (see Clause 4 of this standard);
——The following items are deleted, i.e. the definition of safety system equipment to be qualified, the difference between materials and equipment (aging), the collection and analysis of early data (of aging test), the application of quantitative aging law and maintenance plan (see 5.2, 5.4.3.2, 5.4.3.4.1, 5.4.3.4.2, 5.4.3.4.5 and 5.10 of Edition 2002)
——Many conventional tests and their normative references are deleted (see Clause 5 of this standard);
——The qualification methods are modified (see Clause 5 of this standard; Clause 4 of Edition 2002);
——The qualification program is added (see Clause 6 of this standard);
——The requirements of qualification documentation are modified (see Clause 7 of this standard; Clause 6 of Edition 2002);
This standard was proposed by China National Nuclear Corporation.
This standard is under the jurisdiction of the National Technical Committee 30 on Nuclear Instruments of Standardization (SAC/TC 30).
It was issued for the first time in February, 1991 and firstly revised in August, 2002 and this edition is the second revision.
Qualification of safety class electrical equipment for nuclear power plants
1 Scope
This standard specifies the general requirements for qualification of safety class electrical equipment and its interfaces used in nuclear power plants, including qualification principles, methods and procedures.
This standard is applicable to initially qualifying safety class electrical equipment used in nuclear power plants, maintaining qualified condition and extending qualified life, and updating qualification, as required, if the equipment is modified. The qualification requirements in this standard, when met, demonstrate and document the ability of equipment to perform safety function(s) under applicable service conditions including design basis events, reducing the risk of common-cause failure. Other equipment to be qualified may refer to this standard.
This standard does not provide environmental stress levels and performance requirements.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 13625 Seismic qualification of electrical equipment of the safety system for nuclear power plants
NB/T 20086 Assessing, monitoring and mitigating aging effects on class 1E equipment used in nuclear power plants
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
age conditioning
exposure of sample equipment to environmental, operational, and system conditions (design basis events are not included) to simulate these conditions for a period of time, so as to degrade equipment performance to allow for design basis events simulation tests.
Note: It is revised from the definition 6.2.9 in NB/T 20063-2012.
3.2
condition-based qualification
qualification based on measurement of one or more condition indicators of equipment, its components, or materials, demonstrating the equipment’s ability to perform safety functions during an applicable design basis event.
[Definition 6.1.17, NB/T 20063-2012]
3.3
condition indicator
characteristics of a structure, system or component that can be observed, measured or showing trends, which may be used to infer or directly indicate the current and future operation ability of such structure, system or component within the eligibility criteria.
[Definition 6.1.14, NB/T 20063-2012]
3.4
design basis events; DBE
postulated events used in the design to establish the acceptable performance requirements for the structures, systems, and equipment.
[Definition 2.6, NB/T 20063-2012]
3.5
design life
time period during which satisfactory performance can be expected for a specific set of service conditions.
[Definition 6.1.6, NB/T 20063-2012]
3.6
end condition
condition represented by equipment condition indicator(s) at the conclusion of age conditioning.
3.7
(electrical) equipment
equipment designed and manufactured based on electrical, electronic and programmable electronic technologies to perform specific functions.
3.8
equipment qualification
generation of evidence through tests, analysis or operating experience, to ensure that equipment will operate as specified accuracy and performance requirements under the specified operation and environment conditions.
Note: Equipment qualification includes environmental and seismic qualification.
[Definition 6.1.11, NB/T 20063-2012]
3.9
harsh environment
environment resulting from a design basis event, i.e., loss-of-coolant accident (LOCA), main steam line break (MSLB), and high-energy line break (HELB), excluding safe shutdown earthquake.
3.10
equipment interfaces
mounting and connectors (e.g. junction boxes, joints, gaskets, cables, pipes, sealing elements, etc.) to the equipment at the equipment boundary.
3.11
qualification margin
difference between service conditions and the conditions used for equipment qualification.
3.12
mild environment
environment that would at no time be significantly more severe than the environment that would occur during normal plant operation, including anticipated operational occurrences.
[Definition 6.1.5, NB/T 20063-2012]
3.13
qualified condition
condition of equipment, prior to the start of a design basis event, for which the equipment was demonstrated to meet the design requirements for the specified service conditions.
Note: The qualified condition is related to the characteristic quantity (condition indicator) that characterizes the equipment condition, and these condition indicators are obtained at the end of age conditioning.
3.14
qualified life
time of a structure, system or component that has been proved by test, analysis and/or operating experience to be able to operate within the acceptance criteria under specific service conditions, and meanwhile, to implement its safety function under design basis event or earthquake conditions.
[Definition 6.1.8, NB/T 20063-2012]
3.15
service condition
generic term for environmental, loading, power, and signal conditions during normal operation, abnormal operation and design basis events of the nuclear power plant.
3.16
service life
time period of a structure, system or component from initial operation to removal from service.
[Definition 6.1.10, NB/T 20063-2012]
3.17
significant aging mechanism
aging mechanism that, under normal and abnormal service conditions, causes degradation of equipment that progressively and appreciably renders the equipment vulnerable during its installed life.
[Definition 6.2.6, NB/T 20063-2012]
4 Principles of equipment qualification
4.1 Qualification objective
The primary objective of qualification is to demonstrate with reasonable assurance that safety class electrical equipment for which a qualified life or condition has been established can perform its safety function(s) without experiencing common-cause failures before, during, and after applicable design basis events. Safety class electrical equipment, with its interfaces, shall meet or exceed the equipment specification requirements. This continued capability is ensured through a program that includes, but is not limited to, design, manufacture, qualification, installation, maintenance, periodic testing, and surveillance. The focus of this standard is on qualification, although it affects the other parts of the program.
For equipment located in a mild environment for meeting its functional requirements during normal operation and anticipated operational occurrences, the requirements shall be specified in the technical/purchase specifications. A qualified life is not required for equipment located in a mild environment and which has no significant aging mechanisms.
When seismic testing is used to qualify equipment located in a mild environment, age conditioning prior to the seismic tests is required only where significant aging mechanisms exist. A maintenance/surveillance program should be supplemented with a vendor’s recommendations and operating experience, to ensure that equipment meets the specified requirements.
4.2 Qualified life and qualified condition
Degradation with time followed by exposure to environmental extremes of temperature, pressure, humidity, radiation, vibration and, if applicable, chemical spray and submergence resulting from a design basis event condition can precipitate common-cause failures of equipment. For this reason, it is necessary to establish a qualified life for equipment with significant aging mechanisms. The qualified life determination shall consider degradation of equipment capability prior to and during service. Inherent in establishing a qualified life is that a qualified condition is also established. This qualified condition is the state of degradation for which successful performance during a subsequent design basis event was demonstrated.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principles of equipment qualification
4.1 Qualification objective
4.2 Qualified life and qualified condition
4.3 Qualification elements
4.4 Qualification documentation
5 Qualification methods
5.1 Selection of qualification methods
5.2 Initial qualification
5.3 Extension of qualified life
5.4 Condition monitoring
6 Qualification program
6.1 Equipment specification
6.2 Qualification program plan
6.3 Qualification program implementation
6.4 Modifications
7 Qualification documentation
7.1 Mild environment documentation
7.2 Harsh environment documentation
