GB/T 13177-2026 Preferred power supply for nuclear power plants English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
CCS
National Standard of the People's Republic of China
GB/T 13177-2026
Preferred power supply for nuclear power plants
核电厂优先电源
Issue date: 2026-02-27 Implementation date: 2026-09-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 General design criteria
4.1 General
4.2 Safety classification
4.3 Functions
4.4 Capacity and capability
4.5 Availability
4.6 Independence
4.7 Design basis
5 Specific design criteria
5.1 Interface with the transmission system
5.2 Interface with the switchyard
5.3 Interface with the safety-related power system
5.4 Interface with the alternate AC source
6 Surveillance, control and test requirements
6.1 Surveillance requirements
6.2 Control requirements
6.3 Test requirements
7 Multi-unit considerations
7.1 Shared preferred power supply
7.2 Capacity of shared power supply
7.3 Surveillance
7.4 Protection system
7.5 Design basis
7.6 Shared control and display
Bibliography
Preferred power supply for nuclear power plants
1 Scope
This document specifies the design, surveillance, control and test requirements for the preferred power supply (PPS) for nuclear power plants, as well as for the interfaces between the PPS and the safety-related power system, switchyard, transmission system and alternate AC (AAC) source.
This document is applicable to the PPS for nuclear power plants, and may be referenced for use in other nuclear facilities.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 12788, Criteria for safety-related power systems for nuclear power plants
NB/T 20089, Criteria for protection of safety-related power systems and equipment in nuclear power plants
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
acceptable
Proven by the nuclear power plant safety analysis to be in compliance with requirements.
[Source: GB/T 12788-2021, 3.1]
3.2
alternate AC source (AAC)
An AC power source located in or near the nuclear power plant.
Note: The design principles are as follows:
a) Connected to (but normally not connected to) the preferred power supply or the on-site standby (emergency) AC power system.
b) Low probability of common-mode failure with the preferred power supply or the on-site standby (emergency) AC power source.
c) Capable of providing power in a timely manner after a station blackout.
d) Has sufficient capacity and reliability to meet the following requirements for the operation of required systems:
To cope with station blackout accidents;
To achieve and maintain a safe shutdown state of the nuclear power plant within the required time (design extension conditions).
3.3
preferred power supply (PPS)
A power source that, under accident and post-accident conditions, preferentially supplies power to the safety-related power system from the transmission system.
[Source: GB/T 12788-2021, 3.19]
3.4
station blackout
A postulated initiating event in which all AC power sources supplying the buses of safety-important and non-safety-important distribution panels in the nuclear power plant are lost, but AC power supplied to the buses from on-site batteries through inverter devices or from the alternate AC source is not lost.
Note: The loss of all AC power sources supplying the buses of safety-important and non-safety-important distribution panels means the loss of off-site power, accompanied by turbine trip and failure of the on-site standby (emergency) AC power source.
[Source: GB/T 41143-2021, 3.13, modified]
4 General design criteria
4.1 General
From the transmission system to the safety-related power system, the preferred power supply (PPS) shall be configured with two or more transmission lines. Typical design examples are shown in Figures 1 to 5. Passive nuclear power plants may refer to these for implementation.
4.2 Safety classification
The preferred power supply is not part of the safety-related power system and is not required to comply with the requirements for redundancy, independence, isolation, single-failure criterion, seismic qualification and equipment qualification applicable to safety-related equipment.
4.3 Functions
When required, the preferred power supply supplies power for safe shutdown and safety-related systems. Under all operating conditions of the nuclear power plant, the preferred power supply may supply power to both safety-related and non-safety-related buses.
4.4 Capacity and capability
Each line of the preferred power supply shall have sufficient capacity and capability to supply power to the required equipment to ensure that:
a) The consequences of anticipated operational occurrences do not exceed the prescribed acceptable fuel element design limits and reactor coolant pressure boundary design conditions;
b) The core is cooled during design basis accidents of the nuclear power plant, and the integrity of the containment and other necessary functions are maintained.
Under all operating conditions of the nuclear power plant, each preferred power supply line shall have sufficient capacity and capability to supply power to all electrical loads used to mitigate the effects of design basis accidents and anticipated operational occurrences.
4.5 Availability
During startup and normal operation of the nuclear power plant, at least two lines from the transmission system to the safety-related power system shall be available to meet the following requirements during accidents, post-accident conditions and safe shutdown:
a) The two preferred power supply lines may be connected to the redundant safety-related buses via the non-safety-related power distribution system, as shown in Figures 1 and 2.
b) The non-safety-related wiring shall not affect the independence requirements of the preferred power supply.
c) The two preferred power supply lines being directly connected to each redundant safety-related bus can further enhance availability, as shown in Figures 3, 4 and 5.
d) At least one preferred power supply line shall be capable of automatically supplying power to the safety-related buses within seconds after the occurrence of a design basis accident; the second preferred power supply (PPS) line shall be designed to be available within a sufficiently long period of time as demonstrated by the nuclear power plant safety analysis.
e) For improved designs, both preferred power supply (PPS) lines should preferably be capable of automatically supplying preferred power to the safety-related buses within seconds after the occurrence of a design basis accident, as shown in Figures 3, 4 and 5.
4.6 Independence
The preferred power supply lines supplying power to the safety-related power system shall be physically independent, and their design and arrangement should preferably reduce, as far as is practically feasible, the possibility of simultaneous failure of the two preferred power supply lines under operating conditions, postulated accidents and environmental conditions.
To reduce as much as possible the possibility of simultaneous failure of the two preferred power supply lines, the control circuits of the preferred power supply shall, as far as is practically feasible, be physically independent and independent of the power circuits of the preferred power supply.
If the two preferred power supply lines share a common line structure, an analysis shall be performed to confirm that the reliability of this shared line structure is not less than the overall reliability of the remainder of the preferred power supply.
4.7 Design basis
The preferred power supply system of the nuclear power plant shall have a specific design basis, which shall cover at least the following requirements:
a) The design basis shall include the plant loads and systems supplied by the preferred power supply during startup, normal operation, safe shutdown, accident and post-accident operation, including the required switching sequences and power supply duration.
b) The design basis shall include the environmental conditions to which the preferred power supply may be subjected during operation, such as:
Wind;
Lightning;
Icing;
Temperature variations;
Snow;
Flooding.
Standard
GB/T 13177-2026 Preferred power supply for nuclear power plants (English)
GB/T 13177-2026 Preferred power supply for nuclear power plants English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
CCS
National Standard of the People's Republic of China
GB/T 13177-2026
Preferred power supply for nuclear power plants
核电厂优先电源
Issue date: 2026-02-27 Implementation date: 2026-09-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 General design criteria
4.1 General
4.2 Safety classification
4.3 Functions
4.4 Capacity and capability
4.5 Availability
4.6 Independence
4.7 Design basis
5 Specific design criteria
5.1 Interface with the transmission system
5.2 Interface with the switchyard
5.3 Interface with the safety-related power system
5.4 Interface with the alternate AC source
6 Surveillance, control and test requirements
6.1 Surveillance requirements
6.2 Control requirements
6.3 Test requirements
7 Multi-unit considerations
7.1 Shared preferred power supply
7.2 Capacity of shared power supply
7.3 Surveillance
7.4 Protection system
7.5 Design basis
7.6 Shared control and display
Bibliography
Preferred power supply for nuclear power plants
1 Scope
This document specifies the design, surveillance, control and test requirements for the preferred power supply (PPS) for nuclear power plants, as well as for the interfaces between the PPS and the safety-related power system, switchyard, transmission system and alternate AC (AAC) source.
This document is applicable to the PPS for nuclear power plants, and may be referenced for use in other nuclear facilities.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 12788, Criteria for safety-related power systems for nuclear power plants
NB/T 20089, Criteria for protection of safety-related power systems and equipment in nuclear power plants
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
acceptable
Proven by the nuclear power plant safety analysis to be in compliance with requirements.
[Source: GB/T 12788-2021, 3.1]
3.2
alternate AC source (AAC)
An AC power source located in or near the nuclear power plant.
Note: The design principles are as follows:
a) Connected to (but normally not connected to) the preferred power supply or the on-site standby (emergency) AC power system.
b) Low probability of common-mode failure with the preferred power supply or the on-site standby (emergency) AC power source.
c) Capable of providing power in a timely manner after a station blackout.
d) Has sufficient capacity and reliability to meet the following requirements for the operation of required systems:
To cope with station blackout accidents;
To achieve and maintain a safe shutdown state of the nuclear power plant within the required time (design extension conditions).
3.3
preferred power supply (PPS)
A power source that, under accident and post-accident conditions, preferentially supplies power to the safety-related power system from the transmission system.
[Source: GB/T 12788-2021, 3.19]
3.4
station blackout
A postulated initiating event in which all AC power sources supplying the buses of safety-important and non-safety-important distribution panels in the nuclear power plant are lost, but AC power supplied to the buses from on-site batteries through inverter devices or from the alternate AC source is not lost.
Note: The loss of all AC power sources supplying the buses of safety-important and non-safety-important distribution panels means the loss of off-site power, accompanied by turbine trip and failure of the on-site standby (emergency) AC power source.
[Source: GB/T 41143-2021, 3.13, modified]
4 General design criteria
4.1 General
From the transmission system to the safety-related power system, the preferred power supply (PPS) shall be configured with two or more transmission lines. Typical design examples are shown in Figures 1 to 5. Passive nuclear power plants may refer to these for implementation.
4.2 Safety classification
The preferred power supply is not part of the safety-related power system and is not required to comply with the requirements for redundancy, independence, isolation, single-failure criterion, seismic qualification and equipment qualification applicable to safety-related equipment.
4.3 Functions
When required, the preferred power supply supplies power for safe shutdown and safety-related systems. Under all operating conditions of the nuclear power plant, the preferred power supply may supply power to both safety-related and non-safety-related buses.
4.4 Capacity and capability
Each line of the preferred power supply shall have sufficient capacity and capability to supply power to the required equipment to ensure that:
a) The consequences of anticipated operational occurrences do not exceed the prescribed acceptable fuel element design limits and reactor coolant pressure boundary design conditions;
b) The core is cooled during design basis accidents of the nuclear power plant, and the integrity of the containment and other necessary functions are maintained.
Under all operating conditions of the nuclear power plant, each preferred power supply line shall have sufficient capacity and capability to supply power to all electrical loads used to mitigate the effects of design basis accidents and anticipated operational occurrences.
4.5 Availability
During startup and normal operation of the nuclear power plant, at least two lines from the transmission system to the safety-related power system shall be available to meet the following requirements during accidents, post-accident conditions and safe shutdown:
a) The two preferred power supply lines may be connected to the redundant safety-related buses via the non-safety-related power distribution system, as shown in Figures 1 and 2.
b) The non-safety-related wiring shall not affect the independence requirements of the preferred power supply.
c) The two preferred power supply lines being directly connected to each redundant safety-related bus can further enhance availability, as shown in Figures 3, 4 and 5.
d) At least one preferred power supply line shall be capable of automatically supplying power to the safety-related buses within seconds after the occurrence of a design basis accident; the second preferred power supply (PPS) line shall be designed to be available within a sufficiently long period of time as demonstrated by the nuclear power plant safety analysis.
e) For improved designs, both preferred power supply (PPS) lines should preferably be capable of automatically supplying preferred power to the safety-related buses within seconds after the occurrence of a design basis accident, as shown in Figures 3, 4 and 5.
4.6 Independence
The preferred power supply lines supplying power to the safety-related power system shall be physically independent, and their design and arrangement should preferably reduce, as far as is practically feasible, the possibility of simultaneous failure of the two preferred power supply lines under operating conditions, postulated accidents and environmental conditions.
To reduce as much as possible the possibility of simultaneous failure of the two preferred power supply lines, the control circuits of the preferred power supply shall, as far as is practically feasible, be physically independent and independent of the power circuits of the preferred power supply.
If the two preferred power supply lines share a common line structure, an analysis shall be performed to confirm that the reliability of this shared line structure is not less than the overall reliability of the remainder of the preferred power supply.
4.7 Design basis
The preferred power supply system of the nuclear power plant shall have a specific design basis, which shall cover at least the following requirements:
a) The design basis shall include the plant loads and systems supplied by the preferred power supply during startup, normal operation, safe shutdown, accident and post-accident operation, including the required switching sequences and power supply duration.
b) The design basis shall include the environmental conditions to which the preferred power supply may be subjected during operation, such as:
Wind;
Lightning;
Icing;
Temperature variations;
Snow;
Flooding.
