SMRs & ADVANCED REACTORS | RITM-200N
● Liquid boron injection system (active); ● In-vessel retention system of core melt; ● Passive heat removal system (PHRS); ● Steel enclosure of the reactor (passive); ● Hermetic containment of the reactor building (passive); ● Passive autocatalytic recombiners (PAR); ● An emergency power supply system (mobile diesel generator)
The reactor building and balance of plant The main element of the small modular nuclear power plant is the reactor building, where the reactor plant and its main systems are housed. The reactor building is of a frame type and is made from monolithic reinforced concrete with dimensions 36x36 m and has four above the ground and four below ground floors. The floors and vaulted covering are also made of monolithic reinforced concrete. The operational floor of the reactor building is above ground level (+ 9 m). In the centre of the containment, there is an octagonal shaft made of reinforced concrete measuring 12 m wide and 20 m high, the shaft bottom elevation is - 11.2 m. The walls of the shaft, as well as other rooms which contain radiation sources, are made of concrete with a density of 4.2 t/m3
and provide biological protection for
personnel from ionising radiation. The steam turbine is a single-shaft design consisting of a high-pressure and low-pressure rotors. A coupled three- phase synchronous generator is air cooled with rated power of 55 MW, a rotational speed of 3000 rpm and a voltage of 10.5 kV at the generator terminals. Both the steam turbine unit and the complete turbo-generator set are housed in the turbine building. Superheated steam from steam generating elements (tubes) enters the high- and low-pressure sections of the turbine and exhaust steam is condensed in the condenser by cooling water and the condensate is directed through series of low-pressure heaters where the condensate is heated by the extraction steam drawn from the low pressure turbine. The condensate polishing unit maintains the water quality of condensate (feed water) before it is directed to the steam generators from the deaerator. In the deaerator,
oxygen and other gasses are removed and the feed water is heated further to the required parameters by the extraction steam. Daily power maneuvering is from 30 to 100% of the
nominal power output and the plant is capable of power regulation at the rate of 6% of Nnom/min by changing the feed water flow rate. Power evacuation is carried out at 110 kV. Reserve sources of power supply for the plant’s internal needs are from the reserve diesel genset (DG) for normal operation, the reserve DG set of the emergency power supply system (EPS) and batteries. During the startup the modular DG sets provide 100% of the load whereas during normal operation, the power supply for the nuclear plant’s own needs is provided by a turbogenerator. The reserve and emergency diesel generators are held in standby mode and ready for automatic start-up. In the event of an accident at the turbogenerator or in the process part of the unit, the generator is switched off, and the power supply to the installation is provided from the reserve diesel station. The instrumentation and control system of SMR unit is
designed for: ● Control and monitoring of all important processes, parameters and equipment
● Protection, as well as automatic regulation of plant parameters
● Diagnostics of processes and equipment ● Monitoring and display of plant parameters in all operating modes.
The instrumentation and control system is implemented as a multi-level, distributing and integrating system, which ensures the structural, functional and interfacial independence of its subsystems. This results in preservation of the functions of individual subsystems and their elements in the event of failures in the automated control system, including at individual levels of its hierarchy. The architecture of the control system from the point of view of ensuring safety in the event of failures is based on the application of the defence-in-depth principle. Multi- level protection using independent automated control subsystems ensures the fulfilment of each main function during the entire duration of various operating modes, taking into account common cause failures. The automated I&C of the SMR is a unified system which includes technical, mathematical, metrological, organisational, and information support, as well as operational and design documentation. It includes the technical means that carry out the entire range of monitoring, control and management operations including collection, processing, transmission and distribution of information, and the formation and implementation of control actions. Furthermore, the automated I&C system considers the maximum use of unified hardware and software based on fail-safe circuitry and contains built-in monitoring and testing tools. The automated I&C system also facilitates further modernisation and expansion at all levels of its hierarchy, as it complies with protocols of international standards and the modular structure of lower- level software and hardware.
Above: The first RITM-200N is due for deployment in Yakutia. Commissioning is planned for 2028
40 | May 2024 |
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Operation and construction of the RITM-200N Normal operation of the reactor is provided both in stationary modes in the range of 30-100% of nominal power and power manoeuvring modes which provide the ability
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