RU125782U1 - EMERGENCY POWER SUPPLY SYSTEM OF NUCLEAR POWER PLANT - Google Patents

Abstract

The emergency power supply system of a nuclear power plant, including diesel generators and batteries connected to the general power supply system of a nuclear power plant via a control unit, characterized in that the gas turbine generator is additionally included in the emergency power supply system, connected to the control unit by an electric cable located in an underground protective box .

Description

The inventive utility model relates to the field of power supply of a nuclear power plant, in particular, concerns electrical safety during reactor shutdown and can be used to increase the reliability of power supply to existing and newly built plants in extreme situations as a backup source for removing residual heat at the first moment of power failure.

The main consumers of the technical water supply system (STV) are turbine condensers, turbine generator (TG) oil coolers and other consumers of turbine compartment auxiliary systems. When de-energizing the unit’s own needs, along with the shutdown of the main equipment, the circulation pumps are turned off. Thus, the STV turns out to be out of work (“RBMK Channel Nuclear Power Reactor.”, M. A. Abramov, V. I. Avdeev, E. O. Adamov and others. Edited by Yu. M. Cherkashov. M. State Unitary Enterprise NIKIET, 2006, p. 160-164). STV delivers process water to the pump and heat-exchange equipment of the power unit, which ensures the operability of systems important to safety. Consumers of their own needs of a power unit with RBMK reactors are divided into three groups:

- the first - consumers of alternating and direct current, which impose increased requirements on the reliability of power supply, do not allow power interruptions for more than a split second under safety conditions in all modes, including the mode of de-energizing the unit’s own needs, and requiring the availability of power after emergency protection operation (AZ ) reactor;

- the second - AC consumers, making high demands on the reliability of power supply, allowing power interruptions for a time determined by the safety conditions (from tens of seconds to several minutes);

- third - AC consumers who do not have high requirements for the reliability of power supply, allowing power interruptions.

The emergency power supply system refers to safety systems and is intended to power consumers of safety systems in emergency conditions, accompanied by a blackout of the unit's own needs. Emergency power supply systems are divided into two groups. Consumers of the first group include equipment and servo-drivers of an integrated system for monitoring, controlling and protecting the reactor, centralized control systems for the technological process of the power unit, quick-acting valves of the emergency cooling system of the reactor (SAOR), shut-off valves of the accident localization system (ALS), instrumentation and automation, radiation monitoring system, emergency lighting, operational control, protection and alarm circuits. Consumers of the second group include mechanisms that ensure the cooldown of the reactor and the localization of the accident in emergency conditions, accompanied by a complete loss of voltage on the tires of the unit’s own needs (SAOR pumps, emergency power electric pumps (APS), cooling system cooling pumps, process water pumps, sprinkler-cooling pumps systems, fire pumps). The emergency power supply system includes devices necessary for the conversion and distribution of electricity. To perform the specified functions in case of loss of normal power sources, the system includes autonomous power sources: batteries and diesel generators. The project provides three independent channels to power consumers of the emergency power supply system, based on the use of three diesel generators and high-capacity batteries. In the event of the disappearance of voltage from the working and backup transformers of their own needs (complete de-energization of their own needs), the power comes from an autonomous source - a diesel generator. The diesel generator start-up time until the first stage load is taken is about 15 s. For each power unit of the nuclear power plant, it is planned to install one diesel engine in each of three isolated building cells - a 6.3 MBt generator with a voltage of 6.3 kV. Each RDES cell is equipped with autonomous fuel, oil and air supply systems (for start-up), as well as cooling, heating, ventilation, power supply systems for own needs, control and monitoring. Diesel engines are launched using compressed air, which is stored in two cylinders. There is enough air supply for six consecutive starts. Cylinder replenishment with compressed air is provided from two automated compressors, which are also serviced by experts in shifts. RDES is fully automated and provides for the launch and operation without constant maintenance of operational personnel. In each channel of the emergency power supply system, autonomous power sources for consumers of the first group are provided with rechargeable batteries operating in the constant charge mode, selected from the conditions of their autonomous operation in the mode of de-energizing the unit’s own needs for 30 minutes. Maintenance of three diesel generators in standby mode requires significant material costs. By the example of events that happened at nuclear power plants in Japan, it can be seen that the emergency power supply system focused on the use of diesel generators and batteries can fail when several external negative events are superimposed. Moreover, the start-up time of a diesel generator normally defined for 15 seconds in extreme situations can be very different from the standard, which can lead to problems with cooling the reactor due to lack of electricity. Requirements for emergency power supply systems are described in the book Feldman NL, Chernovets AK “Features of the electrical part of nuclear power plants”, Energoatomizdat, 1987, pp. 40-41, Fig. 2-3. In the prior art, a patent for the invention of the Russian Federation No. 2258996 with priority dated 06/09/2003, IPC Н02Y 9/00, "Emergency power supply system of a nuclear power plant" was also revealed.

The closest analogue of the claimed utility model is the publication: IAEA Safety Guide 50SG-D7. “NPP emergency power supply systems”, p.6-9. According to the description of the emergency power supply system (p. 6) presented on pages 6-9, it provides for the use of diesel generators and batteries connected to the general power supply system of a nuclear power plant through a system control unit as backup sources of electrical energy. The number of diesel generators is equal to the number of turbogenerators. The standby diesel power plant is an autonomous single-unit power plant that performs the functions of a single channel providing a security system. To maintain diesel engines in constant readiness for start-up, a “hot reserve” system is used, the operation of which is automated. The system is quite cumbersome, provides for the presence of powerful batteries and a cylinder of compressed air.

The disadvantage of the closest analogue is the bulkiness of the system, the difficulty of operating and maintaining it in constant readiness for action, and the significant duration of the launch. In addition, there are certain difficulties in the use of diesel fuel: storage, feed system and combustion.

The purpose of the claimed utility model is to further increase the reliability of the emergency power supply system of a nuclear power plant.

The essence of this technical solution lies in the fact that in the emergency power supply system of a nuclear power plant, including diesel generators and batteries connected to the general power supply system of a nuclear power plant through a control unit, it is proposed that an emergency gas supply system include an additional gas turbine generator connected to the control unit electric cable, located in the underground protective box.

The presence of an additional electric generator operating on liquefied gas greatly simplifies the operation of the emergency power supply system of a nuclear power plant, as storage of liquefied gas is simpler, and gas turbine operation is more reliable. In addition, the presence in the emergency power supply system of electric energy sources operating on different fuels increases the reliability of the system as a whole.

Figure 1 presents a diagram of an emergency power supply system of a nuclear power plant, illustrating the essence of the claimed utility model, where:

1 - power supply in the normal operation of the unit (power system, turbogenerator of a nuclear power plant),

2 - power source in the emergency cooldown mode of the reactor under conditions of complete blackout of the power system (batteries, diesel generators),

3 - source control unit 1, 2, 6,

4 - a consumer to operate the unit at power (main circulation pump, circulation pump, feed pump, etc.),

5 - consumers of the first category (control, information, protective systems) and the second category for cooling the reactor - emergency feed pump, hardware pump, etc.,

6 - the proposed additional source of power supply in the mode of deenergizing the power system is a gas turbine generator.

The operation of the circuit is as follows.

Option A - during normal operation of a nuclear power plant and power supply system for consumers. Consumers 4,5 are provided with power from source 1 through switch 3.

Option B - when the power system is switched off by switch 3, consumers 5 are connected to source 2.

Option C - with full or partial loss of emergency power from source 2 (option B) include an additional power supply 6 through the control unit 3, which provides power to consumers 5.

Claims (1)

The emergency power supply system of a nuclear power plant, including diesel generators and batteries connected to the general power supply system of a nuclear power plant through a control unit, characterized in that the gas turbine generator is additionally included in the emergency power supply system connected to an electric cable control unit located in an underground protective box .

Images