Russia claims 100 times smaller nuclear reactor than submarine reactors but with more power

Russia in a speech by Putin claims it has a new nuclear reactor that is 100 times smaller than those used by nuclear-propelled submarines and generates more power. The reactor can also reach its peak power 200 times faster than a conventional nuclear power plant

The miniaturization of a nuclear reactor will give Russia another advanced weapons system in the form of a high-endurance underwater drone. The drone can dive “really very deep” and travel between continents at a speed that is several times higher than that of a submarine, a modern torpedo or even a surface ship.

The highly-efficient onboard miniaturized nuclear reactor powers the flight. Such a missile can fly low enough to avoid early detection, can change course to avoid enemy anti-missile assets along its path, and maneuver to pierce the anti-missile systems protecting its target.

Nextbigfuture has written hundreds of articles on all of the advanced nuclear reactor systems that have been made or have been proposed. What Russia is claiming would take something like an advanced molten salt nuclear reactor combined with something like an advanced super-critical CO2 turbine or another batch of advanced reactor innovations. If they did then it would not make sense to use them only for such trivial purposes as infinite duration nuclear cruise missiles. Russia would be factory mass producing them or something slightly easier to make and dominating world energy production. Russia can only be talking about an unshielded reactor to directly power a jet engine.

The Russian Borei-class submarine uses the OK-650 reactor with OK-9 GTZA (Turbine). This pressurized water reactor (PWR) uses 20-45% enriched uranium-235 fuel to produce 190 MW of power. This means 21 Kg is needed for each kilowatt of power.

The reactor + steam generator would weigh 37284*21=782964 Kg (approximately 782 tons), not taking into account the weight of the shield tank and foundation.

The weight of the shield tank and foundation is about 261 tons. The total weight would then be 1043 tons.

Russia is thus claiming about 10 tons or reactor and turbine to generate about 200 megawatts in order to be 100 times smaller and generate more power than a sub reactor. This flips from having more weight per kilowatt to more kilowatts than weight. Not 20 kilograms per kilowatt but 20 kilowatts per kilogram. The super-energy density includes power conversion and shielding.

Nextbigfuture thinks the claim of a hundred times smaller reactor is BS. Russia would have to have advanced molten salt reactors to make the power generation work and they do not. Russia would have to have supercritical CO2 turbines for lightweight power generation and they do not.

What is technologically possible if for Russia to have gone back to revise and update what Russia and the US were trying to do with the 1960s Project Pluto. This would be an unshielded nuclear reactor that produces heat to power a jet engine. The design would spew radiation and would be very dangerous. The Russians have said it would be an unmanned drone. So radiation hardened electronics could fly it. It would be a hundred times lighter because it would have no radiation shielding and it would use the heat directly for the engine.

Other nuclear reactor designs that are lower weight and high power density

Molten salt nuclear reactors can be lower weight and higher power density. The current designs that are targeting the commercial energy generation markets are not trying to reach the highest power densities. The commercial designs are looking to get the fastest regulatory approvals.

Terrestrial Energy (of Canada) is trying to develop integral molten salt nuclear fission reactors. These nuclear reactors would have about 20-200 times less volume than conventional nuclear fission reactors.

The US, Europe and China are trying to develop supercritical carbon dioxide turbines that would have 100 times less volume than regular steam turbines. The more compact turbine would be needed to convert the heat into electricity.

By shrinking the nuclear reactor and the turbine by 100 times, plenty of other vehicles are made possible. Various nuclear ships and submarines can be revamped. Advanced molten salt nuclear could achieve energy densities that Russia is claiming but would need to be combined with innovations on the power conversion side to change heat into electricity.

The 650 MWth IMSR (Integrated Molten Salt) reactor is about the same size as the smAHTR (125 MWth) reactor.

The smAHTR reactor is 9 meters tall (30 feet) by 3.5 meters (12 feet) in diameter.

The 220 MWth S8G reactor for the Ohio submarines is 42 feet in diameter, 55 feet long; 2,750 tons

A 650 MW thermal integrated molten salt reactor with a supercritical CO2 turbine would have about 400 MWe of power with about 200 tons of weight. This would be about 2 kW/kg.

There have been other molten salt designs with about 18 KW of power per liter. There were early molten salt reactor designs and the engineers believed that they can achieve 100 kW per liter.

Project Pluto

In the 1960s, the US had Project Pluto for nuclear powered aircraft. Nuclear-powered ramjets would power a cruise missile, called SLAM, for Supersonic Low Altitude Missile. In order to reach ramjet speed, it would be launched from the ground by a cluster of conventional rocket boosters. Once it reached cruising altitude and was far away from populated areas, the nuclear reactor would be made critical. Since nuclear power gave it almost unlimited range, the missile could cruise in circles over the ocean until ordered “down to the deck” for its supersonic dash to targets in the Soviet Union. The SLAM as proposed would carry a payload of many nuclear weapons to be dropped on multiple targets, making the cruise missile into an unmanned bomber. After delivering all its warheads, the missile could then spend weeks flying over populated areas at low altitudes, causing tremendous ground damage with its shock wave and radiation from its unshielded reactor. When it finally lost enough power to fly, and crash-landed, the engine would have a good chance of spewing deadly radiation for months to come.

In 1957, the Lawrence Radiation Laboratory (later Lawrence Livermore National Laboratory) began detailed design studies of ramjet propulsion reactors. The flight reactor was intended to have thermal power in excess of 500 megawatts, but to prove the concept a sub-scale reactor was built first. This reactor, designated Tory II-A, had a design power of 155 megawatts. It heated incoming air to a temperature of 1080 °C, and had a flow rate of 320 kg/sec.

With the success of Tory II-A, work began on Tory II-C, a full-scale, flight-weight reactor capable of sustained low altitude flight in excess of Mach 3. With design power of 500 megawatts and much greater airflow, the tank farm had to be expanded by a factor of ten, employing 40 km (25 miles) of oil well casing pipe, which took five days to fill with air.

There are now public documents about the Project Pluto work.

LANL Megapower reactor will be pretty compact but only 2 megawatts and not 200 megawatts

One vSMR concept being developed by Los Alamos National Laboratory (LANL), which the Task Force reviewed, is the “MegaPower” reactor [Patent No. US 20160027536 A1].

Mobile heat pipe cooled fast reactor system US 20160027536 A1

A mobile heat pipe cooled fast nuclear reactor may be configured for transportation to remote locations and may be able to provide 0.5 to 2 megawatts of power. The mobile heat pipe cooled fast reactor may contain a plurality of heat pipes that are proximate to a plurality of fuel pins inside the reactor. The plurality of heat pipes may extend out of the reactor. The reactor may be configured to be placed in a standard shipping container, and may further be configured to be contained within a cask and attached to a skid for easier transportation.

In this concept, the nuclear fuel is uranium oxide enriched up to 19.5% in uranium 235. This level of low enrichment is considered “non-weapons grade” from a proliferation standpoint. The large mass of fuel is encapsulated in a solid steel monolith to form a sub-critical nuclear core which is surrounded by a material that reflects decay neutrons emanating from the uranium metal core back into the core, in a controlled way, causing a sustained nuclear reaction (a “critical reaction”). The thermal energy created by the fission reactions is removed from the uranium metal core by heat pipes, which in turn produce electrical energy via open-air Brayton or supercritical carbon dioxide Stirling engines. This concept is designed to provide 2 MW of electricity and another 2 MW of process heat for 12 years of continuous operation, weighs about 35 metric tons, and is transportable by air and highway. Funding from NASA and Laboratory Directed Research and Development programs is being leveraged to mature MegaPower. The system could be connected to the generators and operated within 72 hours upon arrival.

The reactor system can be shut down, cooled, disconnected, and “wheeled out” in less than seven days. The reactor core and all other critical equipment are housed in special armor, which protects the reactor systems from beyond the design basis attack, and also shields personnel and environment from the core radiation during operation and transport. The design is mature, but would require additional investment for demonstration. Every component has technology readiness level (TRL) of six 40 or better, with integration of the components into system prototypes the major remaining work to be done. A projection has been made that a unit could be available for concept demonstration in five years.

Lessons learned from the kiloPower development program (for NASA and possible Mars usage) are being leveraged to develop a Mega Watt class of reactors termed MegaPower reactors. These concepts all contain intrinsic safety features similar to those in kiloPower, including reactor self-regulation, low reactor core power density and the use of heat pipes for reactor core heat removal. The use of these higher power reactors is for terrestrial applications, such as power in remote locations, or to power larger human planetary colonies. The MegaPower reactor concept produces approximately two megawatts of electric power. The reactor would be attached to an open air Brayton cycle power conversion system. A Brayton power cycle uses air as the working fluid and as the means of ultimate heat removal.

MegaPower design and development process will rely on advanced manufacturing technology to fabricate the reactor core, reactor fuels and other structural elements. Research has also devised methods for fabricating and characterizing high-temperature moderators that could enhance fuel utilization and thus reduce fuel enrichment levels.

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