China spending US$3.3 billion on molten salt nuclear reactors for faster aircraft carriers and in flying drones

China will spend 22 billion yuan (US$3.3 billion) on two prototype molten salt nuclear reactors.

Two molten salt nuclear reactors will be built in the Gobi Desert in northern China.

* Molten salt reactors can produce one thousandth of the radioactive waste of existing nuclear reactors because of deep burn. More complete conversion of the nuclear fuel.
* Molten salt reactors can have designs that are proof against nuclear meltdowns
* The chinese reactors could use thorium. China has some of the world’s largest reserves of the thorium metal.

The Chinese project has been funded by the central government and the two reactors are to be built at Wuwei in Gansu province, according to a statement on the website of the Chinese Academy of Sciences. The lead scientist on the project is Jiang Mianheng – the son of the former Chinese president Jiang Zemin – and it is hoped the reactors will be up and running by 2020.

The US air force built a 2.5-megawatt molten salt reactor in the 1950s as part of a program to develop nuclear-powered aircraft engines.

The reactors use molten salt rather than water as a coolant, allowing them to create temperatures of over 800 degrees Celsius, nearly three times the temperature of a commercial pressure water nuclear plant. The superhot air had the potential to drive turbines and jet engines and in theory keep a bomber flying at supersonic speed for days.

Yan Long, a researcher involved in the Chinese project at the Shanghai Institute of Applied Physics, said the Gansu facility might eventually help China develop a thorium-powered warship or aircraft.

He said it was now possible to build a very small molten salt reactor and that after years of research and government funding, scientists had developed special alloy and coating materials to prevent chemical corrosion.

The reactors in Gansu were designed to demonstrate the feasibility of the technology.

Both reactors will be underground and the heat they generate will reach 12 megawatts. The heat will be channelled to a power generation plant, several factories and a desalination plant by the lake to produce electricity, hydrogen, industrial chemicals, drinking water and minerals.

After the experiment, China may move on to commercial or military use of the technology on a larger scale, Yan said.

“We are now developing new materials for warships. The materials must come with relatively low cost for mass production and they must be compact and light, otherwise the reactor won’t fit in a ship.

Chen Fu, a thermal physicist at the Harbin Institute of Technology involved in the development of new power generation systems for China’s navy, said the heat generated by a thorium molten salt reactor could be perfect to help generate power on a warship.

“It should be able to generate enough electricity for propulsion and electric equipment on an aircraft carrier,” he said.

Chen said the higher the temperature, the higher the power generation efficiency – a thorium-powered carrier could operate faster and longer than existing carriers using uranium as fuel.

A military drone researcher in Beijing said a molten salt reactor could be used on a new generation of large, endurance drones operating at very high altitudes because it could be made very small and its operation did not require water.

“These drones would stay aloft over the oceans such as the Pacific. They would serve as a platform for surveillance, communication or weapon delivery to deter nuclear and other threats from hostile countries,” said the researcher, who asked not to be named.

“A nuclear-powered drone may be technically more feasible than manned aircraft because it does not require building a cockpit with lead to protect the human crew from radiation. It will also have more public acceptance. If an accident happens, it crashes into the sea,” the person said.

Molten Salt reactors can become more powerful and smaller than current submarine nuclear reactors

U.S. naval reactors are pressurized water reactors, which differ from commercial reactors producing electricity in that:

Nuclear submarines have compact reactors that use higher enrichment than land based reactors. The reactros have a high power density in a small volume and run either on low-enriched uranium (as do some French and Chinese submarines) or on highly enriched uranium (over 20% U-235), current U.S. submarines use fuel enriched to at least 93%, compared to between 21–45% in current Russian models, although Russian nuclear-powered icebreaker reactors are enriched up to 90%),

Naval nuclear reactors do not use uranium oxide but a metal-zirconium alloy (c.15% U with 93% enrichment, or more U with lower enrichment),

The reactors have long core lives, so that refueling is needed only after 10 or more years. New naval nuclear cores are designed to last 25 years in carriers and 10–33 years in submarines,

The designs enable a compact pressure vessel while maintaining safety.

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 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

So the IMSR with supercritical CO2 turbines would have almost 3 times as much power in an area about 16 times less volume. In the range of 150-200 cubic meters and about 200-400 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. Those are early generation designs and the engineers believe that they can achieve 100 kW per liter.

There is a Molten Salt Reactor Review by Energy Process Developments

Terrestrial Energy – Integrated MSR (IMSR)

The Integral MSR is also based on the MSR Experiment but has been modified to have a more sealed, passive approach. The design team is based in Canada with international involvement and support. An 80 MWth prototype reactor is proposed.

Recently , Terrestrial Energy Inc.’s (TEI) announced completion of the first phase of the Canadian Nuclear Safety Commission’s (CNSC) pre-licensing vendor design review.

They submitted the Integral Molten Salt Reactor (IMSR) design to CNSC in the fall of 2016, taking the first step in a several step process leading toward the construction and operation of power generation units. As promised, the CNSC completed its non-binding review of the design information within a year of the application submission.

Operating in the thermal spectrum with a graphite moderator inside the sealed unit, it can fit on the back of an articulated truck. This unit contains the fuel salt, moderator, heat exchangers and pumps. The plant is fuelled with 5% low enriched uranium where the U-235 is denatured with U-238. This core is modular, designed for a high power density and replacement after a seven year cycle in a plant with an overall lifetime of over thirty years. This ‘seal and swap’ approach reduces on site complications and risks. Using low enriched uranium, it has a fuel cycle with which regulators are familiar. This proposal is suitable for developing fully and launching commercially immediately.

Terrestrial Energy’s IMSR features self-contained reactor Core-unit, where all key components are permanently sealed for operating lifetime. At the end of 7-year design life, the IMSR Core-unit is shut down to cool. Power is switched to a new IMSR Core-unit, in an adjacent silo within the facility. Once sufficiently cool, the spent IMSR Core-unit is removed and prepared for long-term storage, a process similar to existing industry protocols for long-term nuclear waste containment. The sealed nature of the IMSR Core-unit offers low-cost operational safety and simplicity.

Dr. David LeBlanc presented for Terrestrial Energy at TEAC7 (Thorium Energy Alliance Conference #7), held in 2015 Palo Alto.

Flibe Energy – Liquid Fluoride Thorium Reactor (LFTR)

Flibe Energy, one of the first to resurrect the molten salt reactor concept, and based in the USA, proposes a 2MWth two fluid breeder design. It is based on work carried out by the Oak Ridge National Laboratory team in the 1970’s. It operates in the thermal spectrum moderated by graphite. Its fissile element is uranium-233 which is bred from thorium in a blanket salt at the outer edge of the reactor core.

Kirk Sorensen estimates that it will cost “several hundred million dollars” to get to the first LFTR

Martingale Inc. – ThorCon

The ThorCon design is a single fluid thorium converter reactor that operates in the thermal spectrum. It is in principal similar to the MSR Experiment and its fuel is denatured using a combination of U-233 from thorium and U-235 enriched from mined uranium. Its core is graphite moderated and the full scale version runs at 550MWth. A centralised facility is proposed to reprocess the spent fuel salt from multiple plants. The design team comes from a shipping background and brought in nuclear expertise from members of the MSR community from across the United States. As a concept, a pilot scale version of this plant would be similar to the MiniFuji, a concept that the Japanese have been working on for a long time

Moltex Energy – Stable Salt Reactor (SSR)

The Stable Salt Reactor has a design team based in the UK. It is a fast spectrum pool type reactor. Unlike all the other design concepts considered, its fuel is static and is not derived from the two molten salt reactors developed at Oak Ridge National Laboratory. Its static fuel concept was actually correctly rejected as unsuitable for an aircraft borne reactor by ORNL and apparently never reconsidered when the program moved to ground based reactors. The full size version is proposed at 1GWe and the prototype at 150MWth, but run at a lower power.

Seaborg Technologies – Seaborg Waste Burner (SWaB)

The SWaB prototype proposal is a 50 MWth single fluid reactor that operates in the thermalepithermal spectrum. It is graphite moderated and fuelled by a combination of spent nuclear fuel and thorium. The design team based in Denmark, is a combination of physicists and chemists from the Niels Bohr Institute and the Technical University of Denmark. It is designed to take spent fuel pellets directly for de-cladding and insertion into the fuel salt.

Transatomic Power Reactor (TAP)

Transatomic Power’s proposed design is a 20MWth demonstration reactor which is similar to the MSR Experiment except for its utilisation of zirconium hydride (instead of graphite) as a moderator and LiF-based salt (instead of a FLiBe-based salt). These changes enable a twenty fold increase in power density and the use of very low enriched fuel. It operates in the thermal spectrum and with a significant neutron flux in the fast spectrum. It is a single fluid configuration.

SOURCES – Youtube, Energy Process Development, Moltex Energy, Thorcon, Terrestrial Energy, Flibe Energy, South China Morning Post