BASIC TECHNICAL PARAMETERS
Parameter Value
Technology developer, country of origin
JSC “Afrikantov OKBM”, Rosatom,Russian Federation
Reactor type Integral PWR
Coolant/moderator Light water / light water Thermal/electrical capacity,
MW(t)/MW(e)
175 / 50
Primary circulation Forced circulation NSSS Operating Pressure
(primary/secondary), MPa
15.7 / 3.83 Core Inlet/Outlet Coolant
Temperature (oC)
277 / 318
Fuel type/assembly array UO2 (metal-ceramic fuel) pellet/hexagonal Number of fuel assemblies in the core 241
Fuel enrichment (%) < 20
Core Discharge Burnup (GWd/ton) - Refuelling Cycle (months) Up to 120
Reactivity control mechanism Control and protection system rod drive mechanism
Approach to safety system Combined (active and passive) system
Design life (years) 60
NPP footprint (m2) 3360
RPV height/diameter (m) 8.6 / 3.45
RPV weight (metric ton) 265
Seismic Design (SSE) 0.3g
Fuel Cycle Requirements or Approach Without on-site refueling Distinguishing features Integral reactor, in-vessel corium
retention, double containment
Design status 6 prototype reactors were
manufactured and installed on icebreakers (two are in the process of testing)
1. Introduction
JSC “Afrikantov OKBM”‘s RITM series reactors - RITM-200 and RITM-200M are the state-of-the-art development in SMR line. They have been designed by the JSC “Afrikantov OKBM” and have incorporated all the best features from its predecessors. Floating NPPs equipped with RITM reactors are available for commercial implementation in medium/long term. RITM-200M reactor is a development from the RITM line with refuelling cycle increased up to 10 years.
2. Target Application
The RITM-200M design was developed for the Optimized Floating Power Unit (OFPU). The OFPU is a power facility in the form of a compact non-self-propelled vessel, having two RITM-200M reactor plants. The Floating power units based on RITM-200M ensure that needs of small settlements or industrial enterprises are covered, as well as the power expanding when need for electrical power is increasing or transfer of the energy source to a new deployment site upon disappearance of their necessity (e.g. upon completion of the development of mineral deposits). OFPU can provide electricity to domestic and industrial consumers. OFPU can also be used for heat supply and water desalination purposes when installing additional equipment. Such power units will become a powerful factor of stability in the development of the region not covered by the single energy system and requiring reliable and economically competitive energy sources.
RITM-200M (JSC “Afrikantov OKBM”,
3. Main Design Features
Design PhilosophyRITM series reactors are the evolutionary development of the reactors (OK-150, OK-900 and KLT-40 series) for Russian nuclear icebreakers with a total operating experience of more than 60 years (more than 400 reactor- years). Due to incorporation of steam generators into the reactor pressure vessel, the reactor system and containment is very compact compared to the KLT-40S. The RITM design makes it possible to increase electric output (by 40% more) and to reduce dimensions (by 45% less) and the mass (by 35% less) in comparison with KLT-40S. The integral reactor configuration almost eliminates the classic large loss-of-coolant accident (LOCA). Active and passive safety systems are applied in the concept to achieve the necessary safety and reliability level due to principles of redundancy, physical separation, and functional independence.
Nuclear Steam Supply System
Nuclear steam supply system of RITM series reactor consists of reactor core, four steam generators integrated in the reactor pressure vessel, four main circulation pumps (MCP), and pressurizer. The main cooling system is based on forced circulation during normal operation and enables natural circulation in an emergency.
Reactor Core
In the RITM series, a low enriched cassette core is applied similar to the KLT-40S, which ensures long-term operation without refuelling and meets international non-proliferation requirements. The core consists of 241 fuel assemblies with 20% enrichment. The service life of the core is up to 10 years.
Reactivity Control
Control rods are used for reactivity control. A group of CPS drive mechanisms is provided for compensation of the excessive reactivity during start-up, operation at power and emergency shutdown of the reactor. Safety rods are provided for quick reactor shutdown and its holding in subcritical state in case of an accident. The design of control and safety rods has been developed on the basis of the drives proven in KLT-40S reactor plant.
Reactor Coolant System
The reactor pressure vessel (RPV) is a thick-walled cylindrical pressure vessel with an all-welded bottom cover and a removable top cover. The reactor plant is designed as an integral vessel with main circulation pumps (MCP) located in separate external hydraulic chambers connected by nozzles. It also includes four steam generator cassettes. Each of the four SGs has three rectangular cassettes; and the four main circulation pumps are installed in a cold loop of the circulation circuit and are divided into four independent circuits. The SGs generate steam of 295°C at 3.82 MPa flowing at 261 (280) t/h. The MCPs are single-stage vane type and have a sealed asynchronous motor with one winding.
Steam Generator
In the RITM series reactors, once-through SGs are applied. The configuration of the steam generating cassettes makes it possible to compactly install them in the RPV.
Pressurizer
The design adopts pressure compensation gas system proved comprehensively in the Russian ship power engineering. It is characterized by a simple design, which increases reliability, compactness, and requires no electric power. The compensation system is divided into two parallel independent groups to reduce the restrictor diameter in the compensatory nozzles of the steam generating unit and to decrease a coolant leak rate in large-break accidents of primary pipeline. It makes possible to use one of pressurizers as a hydraulic accumulator, increasing reactor plant reliability considerably in potential loss-of-coolant accidents.
4. Safety Features
The safety concept of the RITM system is based on the defence-in-depth principle combined with the inherent safety features and use of passive systems. The inherent safety features enable to carry out automatic regulation of power flow density and automatic reactor shutdown, limitation of primary coolant pressure and temperature, heating rate, primary circuit depressurization scope and outflow rate, fuel damage scope, maintaining of reactor vessel integrity in severe accidents and conceptualization of a ‘passive reactor’, resistant to possible abnormalities. RITM optimally combines passive and active safety systems to ensure normal operation and sustainability during design basis accidents.
- Passive pressure reduction and cooling systems area available (system reliability is verified by tests);
- The pressurizer system is divided into two independent sections to minimize the potential coolant leakage;
- Main circulation loop of the primary circuit is located in a single vessel;
- The steam header of primary coolant circulation is added providing safety of the plant during SG and MCP failures.
The staff radiation exposure during normal operation and design basis accidents does not exceed 0.01% of the natural radiation limit. The public radiation exposure in case of severe accident is lower than the value requiring
protective measures.
Approach to and Configuration of the Engineered Safety System
The high safety level of RITM series reactors is achieved both by inherent safety features and a combination of passive and active safety systems. Moreover, redundancy of safety system equipment and trains and their functional and/or physical separation are provided to ensure high reliability. Safety systems are driven automatically by the control system, when controlled parameters achieve appropriate set points. In case of automated systems failure, self-actuating devices will actuate directly under the primary circuit pressure to ensure reactor trip and initiate the safety systems. CPS rods drop into the core by gravity or using a spring when the electromechanical clutches are de-energized ensuring that the reactor will shut down even in case of total plant black out.
Decay Heat Removal System
The residual heat removal system (RHRS) consists of four safety trains:
- Active safety loop with forced circulation through steam generator.
- Active safety loop with forced circulation through primary-third circuit heat exchanger of coolant purification loop.
- Two passive safety loops with natural coolant circulation through steam generators from water tanks.
Evaporated in steam generators, water condenses in air cooled heat exchangers and in water heat exchanger and then flows back to steam generators. After complete water evaporation from the tanks connected to water heat exchangers, the air-cooled exchangers continue provide cooling for unlimited time. Combination of air and water heat exchangers enables to minimize dimensions of the heat exchangers and water tanks.
All safety trains are connected to different steam generators and provide residual heat removal in compliance with the single failure criterion. The active safety trains consist of water tank, pumps, and heat exchanger to ultimate heatsink.
Emergency Core Cooling System
The emergency core cooling system consists of safety injection system (SIS) for water injection in primary circuit to mitigate the consequences of a break loss-of-coolant accident. The system is based on active and passive principles with redundancy of active elements in each train and consists of:
- Two passive pressurized hydraulic accumulators;
- Two active trains with water tanks and two make-up pumps in each train.
In combination with the residual heat removal system the passive safety trains provide a post-accident grace period of 72 hours without operator action or power in case of combination of LOCA and total station blackout.
Containment System
RITM is placed inside containment with overall dimensions of 6.6m×6.4m×16.2m localize possible radioactive releases. In case of severe accident thick wall of the reactor vessel keeps molten corium within the reactor. Water filled caisson under the reactor provides the reactor vessel cooling. The containment integrity is ensured by overpressure relief valve, containment cooling system, and a passive autocatalytic recombiner.
5. Plant Safety and Operational Characteristics
The main characteristics are:- OFPU construction and first fueling in the country of origin;
- Transportation to operation site through the territorial sea of transit countries;
- Power and heat production at operation site in host country (up to 10 years until refueling);
- Return to the country of origin for maintenance and refueling;
- Maintenance and refueling in the country of origin;
- Radwaste management in the country of origin - Return to operation site in the customer’s country.
6. Monitor and Control Systems
An automated control system is provided in the RITM based nuclear power plant to monitor and to control plant processes. This system possesses necessary redundancy with regard to safety function fulfilment and ensures both automated and remote control of the power plant.
RITM Series Safety System
7. General Layout of the Plant
The Optimized Floating Power Unit with RITM-200M reactor plant is designed to supply electricity and desalinated water to coastal or isolated territories, offshore installations, islands, and archipelagos. The OFPU may be rapidly delivered to the site by sea. The only need for its start-up is docking pier and onshore power transmitting infrastructure.The design of the vessel is also being developed to ensure that it is positioned in the open sea without coastal structures. In this case, the energy is supplied to the shore by cable.
8. Approach to the Fuel Cycle
The OFPU is delivered to the site with fresh fuel in its reactors. After completion of the fuel cycle, the OFPU returns to the exporting country together with the spent fuel in its reactors. All operations for production, post-reactor maintenance and reprocessing of spent nuclear fuel are performed in the exporting country.
9. Waste Management System and Waste Disposal Plan
Waste storage occurs within the OFPU (in the water area the waste is neither stored nor processed nor disposed of). The relevant waste of the plant is compact, has a low activity level and it is reliably isolated from the biosphere. Absence of its impact on marine organisms in the deployment water area has been confirmed.
10. Design State and Licensing Status
The RITM series design has been developed in conformity with Russian laws, standards and rules for nuclear power plants and safety principles developed by the world community and IAEA recommendations. In the RITM series design, optimal combination of passive and active safety systems is applied. Reactors are currently manufactured and installed on board nuclear icebreakers; the OFPU design is under development.
11. Development Milestones
2016 First RITM-200 was installed on board Arktika icebreaker 2020
2020
Arktika icebreaker is under testing
Conceptual design of the OFPU with RITM-200M
The OFPU with RITM-200M
OFPU life cycle
MAJOR TECHNICAL PARAMETERS
Parameter Value
Technology developer, country of origin China General Nuclear Power Group (CGNPC),China
Reactor type Loop type PWR
Coolant/moderator Light water / light water Thermal/electrical capacity,
MW(t)/MW(e)
200 / 50
Primary circulation Forced circulation NSSS Operating Pressure
(primary/secondary), MPa
15.5 Core Inlet/Outlet Coolant
Temperature (oC)
299.3 / 321.8
Fuel type/assembly array UO2 pellet / 17x17 square Number of fuel assemblies in the core 37
Fuel enrichment (%) < 5
Core Discharge Burnup (GWd/ton) < 52 Refuelling Cycle (months) 30
Reactivity control mechanism Control rod driving mechanism (CRDM), solid burnable poison and boron solution
Approach to safety systems Passive
Design life (years) 40
RPV height/diameter (m) 7.2 / 2.2
Distinguishing features Floating power boat, once- through steam generator, passive safety system
Design status Completion of conceptual/
program design, preparation of project design
1. Introduction
The ACPR50S is a small modular offshore floating reactor developed by the China General Nuclear Power Corporation (CGNPC) - aiming for high safety and adaptability, modularized design, and multi-purpose applications. It is intended as a flexible solution for combined supply of heat, electricity and fresh water for marine resource development activities, energy supply and emergency support on islands and along the coastal area.
2. Target Application
As an offshore floating SMR, the ACPR50S is designed as a multipurpose power reactor for the following applications: combined energy supply for offshore oil drilling platform; offshore combined energy supply;
coastland and island combined energy supply; energy supply for offshore mining, nuclear power ship; and distributed clean energy for islands together with solar energy and wind power.
3. Main Design Features
Design PhilosophyThe ACPR50S adopts design simplification to reduce cost and investment risks to be competitive with conventional offshore energy sources. Modular design is adopted through standardized and streamlined manufacturing, aiming for shorter construction period as well as lower cost. A long refuelling cycle allows for higher load factors.