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3. Main Design Features
Design PhilosophyKLT-40S is the reactor for Akademik Lomonosov FNPP, intended for reliable power and heat supply to isolated consumers in remote areas without centralized power supply and where expensive delivered fossil fuel is used.
Nuclear Steam Supply System
The steam lines while exiting from the SGs are routed through containment to a set of steam inlet valves, and finally into the turbine building for electricity conversion. Cogeneration equipment could be modified into the medium-low temperature heat process concept if one or multiple separation heat exchangers are positioned between the primary and secondary loops.
Reactor Core
Fuel utilization efficiency is achieved by using dispersion fuel elements. One of the advantages foreseen by the FNPP under construction is long term independent operation in remote regions with decentralized power supply. The design requires refuelling of reactor after every 2.5–3 years of operation. Refuelling is performed 14 days after reactor shutdown when the levels of residual heat releases from spent FAs have reached the required level. The spent nuclear fuel is initially stored on board at the FNPP and then returned to Russian federation. No special maintenance or refuelling ships are necessary. Single fuel loading is done in order to provide maximum operation period between refuelling. The fuel is loaded in the core all at once with all fuel assemblies being replaced at the same time.
Reactivity Control
The control rod drive mechanism (CRDM) is electrically driven and releases control and emergency control rods into the core in case of station black out (SBO). The speed of safety rods driven by electric motor, in the case of emergency is 2 mm/s. The average speed of safety rods being driven by gravity is 30 – 130 mm/s.
Reactor Pressure Vessel and Internals
The KLT-40S reactor has a four-loop forced and natural circulation coolant loop; the latter is used only in the emergency heat removal mode. This reactor is utilized at all operating nuclear icebreakers.
Reactor Coolant System
The reactor has a modular design with the core, steam generators (SGs) and main circulation pumps connected with short nozzles. The reactor has a four-loop system with forced and natural circulation, a pressurized primary circuit with canned motor pumps and leak tight bellow type valves, a once-through coiled SG and passive safety systems. KLT-40S thermal-hydraulic connections comprising external pressurizer, accumulators, and separation heat ex-changer are in proximity of the reactor systems. The pressurizer is not an integral part of the reactor systems and in this design it is formed by one or more separate tanks, designed to accommodate changes in coolant volume, especially severe during reactor start-up. The core is cooled by coolant flowing from core bottom to top, in accordance with typical PWR core flow patterns. However, flow patterns between the core shroud and the RPV inner walls differ significantly from conventional external loop PWR configurations. Once hot coolant exits the top of the core and enters any of the multiple SGs, it uses coaxial hydraulic paths wherein the cold and hot legs are essentially surrounding one another. As hot coolant enters the SG, it begins to transfer thermal energy with the fluid circulating in the secondary loop (secondary side of the SGs).
4. Safety Features
The KLT-40S is designed with proven safety aspects such as a compact structure of the SG unit with short nozzles connecting the main equipment, primary circuit pipelines with smaller diameter, and with proven reactor emergency shutdown actuators based on different operation principles, emergency heat removal systems connected to the primary and secondary circuits. Additional barriers are provided to prevent the release of radioactivity from the FNPP caused by severe accidents. Among them are passive and active physically separated and independent safety systems, I&C systems, diagnostic systems, active cooling train through primary circuit purification system’s heat exchanger thermally coupled with a ’third’ independent circuit exchanging heat energy with ambient sea or lake water, active cooling train through the SGs heat exchangers with decay heat removal accomplished through the condenser which in turn is cooled down by ambient sea or lake water, 2 passive cooling trains through the SGs with decay heat removal via emergency water tank heat exchangers, and venting to atmosphere by evaporation from said tanks. Both active and passive safety systems are to perform the reactor emergency shutdown, emergency heat removal from the primary circuit, emergency core cooling and radioactive products confinement. The KLT-40S safety concept encompasses accident prevention and mitigation system, a physical barriers system, and a system of technical and organizational measures on protection of the barriers and retaining their effectiveness, in conjunction with measures on protection of the personnel, population and environment. The KLT-40S safety systems installed on FNPPs are distinctive from those applied to land-based installations in security of the water areas surrounding the FNPP, anti-flooding features, anti-collision protection, etc. Passive cooling channels with water tanks and in-built heat exchangers ensure reliable cooling to 24 hours.
Engineered Safety System Approach and Configuration
The active components of the protection system are scram actuators for six (6) groups of the control rods.
Decay Heat Removal System
The decay heat removal system is intended to remove core residual heat upon actuation of reactor emergency protection in case of abnormal operation including accidents, as well as to remove residual heat at normal RP decommissioning. The decay heat removal system includes two secondary passive cooling channels via steam generators, one active secondary cooling channel via steam generators and one active cooling channel via the primary/third heat exchanger.
Emergency Core Cooling System
The ECCS is intended to supply water to the reactor for core cooling in accidents associated with primary coolant loss, makeup of primary coolant during process operations, supply of liquid coolant to the reactor at failure of the electromechanical reactor shutdown system, adjustment of water chemistry and hydraulic testing of the primary circuit and associated systems, secondary and third loop sections disconnected at inter-circuit leaks and designed for primary pressure. The ECCS includes high-pressure ECCS subsystem with makeup, high-pressure ECCS subsystem with hydraulic accumulators and Low-pressure ECCS subsystem with recirculation pumps.
Containment System
The containment for the KLT-40S is configured for FNPP applications and is made of steel shell designed to sustain mild pressurization, while the reactor systems are positioned inside a reinforced ‘reactor room’ whose bottom forms a steel-lined tank. This tank can be flooded with cooling water for decay heat removal as well as for shielding purposes. The top portions of the reactor room can be pressurized as the reactor room is plugged by a steel and concrete plug. Once removed, the plug provides access to the reactor systems and to the core for refuelling or maintenance operations.
5. Plant Safety and Operational Performances
The KLT-40S NPP ensures electricity and heat generation within the power range of 10% to 100% for a continuous operation of 26 000 hours. The NPP is designed for manoeuvring speed of up to 0.1 %/s. As a countermeasure against the external impact, the NPP is fitted with both ground safety and floating physical protection means. Structures are designed to be placed in the Arctic zone at the depth of 2 m at freezing temperatures. The FPU and NPP buildings are designed to withstand the crash of an aircraft of 10 tons. Based on analysis, the radiation emission limits are satisfied for all conditions.
6. Electric Power Systems
The electric power system in the FPU is comprised of the following: main electric system; and emergency electric system. The main electric system of the FPU is intended to generate electricity and transmit it to the power system of the region, as well as to transmit electricity to internal consumers. The system includes two main three-phase AC generators of 35 MW each and eight back-up diesel generators of 992 kW each. The emergency electric system supplies electricity to safety system loads in all operation modes, including loss of operating and back-up electric power sources. The FPU has independent emergency electric systems for each reactor plant. Each emergency electric system has two channels with an emergency diesel generator of 200 kW.
Passive emergency shutdown cooling system
System of reactor caisson filling with water
Active emergency core cooling system
Active emergency core cooling system
Active system of liquid absorber Passive emergency core cooling system
(hydraulic accumulators) Passive system of containment emergency
pressure decrease (condensate system)
Active emergency shutdown cooling system (through process condensers)
Containment passive emergency pressure decrease system (bubbling)
Recirculation system pumps
From STP (Standby and emergency feed water pumps)
7. Plant Layout Arrangement
The coastline line of the FCNPP has the complex engineering building with equipment to distribute and transmit electricity to loads and to prepare and transfer heating water to loads and auxiliary buildings, including: two hot water storage tanks; partially in ground tank with slime water; wet storage bunker; two cooling towers; access control point; site enclosure; lighting towers. The coastal line of the FCNPP does not provide for handling nuclear materials and radiation hazardous media.
Reactor Building
The FPU is a flush deck non-self-propelled rack-mounted vessel with hull and multi-layer deckhouse. The medium portion of the FPU has a reactor compartment and nuclear fuel handling compartment. A turbogenerator compartment and electrotechnical compartment are arranged in the ship’s head with respect to the reactor compartment, auxiliary installations compartment and accommodations are arranged in astern. Each reactor plant is arranged within steel pressure containment, which is a reinforced structure of the FPU casing.
The containment is designed for maximum pressure, which can develop during accidents. Onboard the FPU, storages for spent cores and means are arranged that ensure reactor reloading.
Control Building
The KLT-40S reactor is controlled using the operator’s automated workstation through respective control panel located in the central control room. In case it is impossible to carry out control from the central control room, information on the reactor status is obtained and safety systems are activated to make reactors subcritical and control reactor plant cooling using emergency cooling control panels located outside the central control room.
General cross-section view of the FPU
Turbine Generator Building
The steam turbine plant (STP) is intended to convert the thermal power from steam obtained in the KLT-40S reactor to the electric and thermal one to heat water in the intermediate circuit of the cogeneration heating system. The FNPP structure includes two steam turbine plants. Each STP is independent of the other and is connected to its own module of KLT-40S. Heat is delivered to the shore by heating intermediate circuit water, which circulates between FPU and the shore, using steam from adjustable turbine steam extraction.
8. Design and Licensing Status
KLT-40S is the closest to commercialization of all available FNPP designs, and expects deployment through the Akademik Lomonosov FNPP. The KLT-40S is a modified version of the commercial KLT-40 propulsion plants employed by the Russian icebreaker fleet. The environmental impact assessment for KLT-40S reactor systems was approved by the Russian Federation Ministry of Natural Resources in 2002. In 2003, the first floating plant using the KLT-40S reactor system received the nuclear site and construction licenses from Rostechnadzor. The keel of the FNPP carrying the KLT-40S, the Akademik Lomonosov in the Chukotka region, was laid in 2007. The construction of Akademik Lomonosov was completed in 2017. The Akademik Lomonosov has started commercial operation in December 2019 in the town of Pevek in Chukotka region.
9. Development Milestones
1998 The first project to build a floating nuclear power plant was established
2002 The environmental impact assessment was approved by the Russian Federation Ministry of Natural Resources
2006 After several delays the project was revived by Minatom (Russian Federation Ministry of Nuclear Energy) 2012 Pevek was selected as the site for the installation of NPPs. JSC “Baltiysky Zavod” undertook charge of
construction, installation, testing and commissioning the first FPU
2017 Completion of construction and testing of the floating power unit at the Baltic shipyard
2018 Dock-side trials, fuelling, final tests completion with reactor core, attainment of reactor’s first criticality Summer 2019 Transportation of FPU to the town of Pevek
December 2019 Connected to grid on 19th of December in Pevek May 2020 Fully commissioned in Pevek on 22nd of May
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.