The Bill Gates-backed company is developing two Generation IV reactor designs, but is also carrying out research into materials testing and radioisotope production A computer generated mockup of the TerraPower Travelling Wave Reactor. Courtesy TerraPower. In just a few years TerraPower – the US nuclear company backed by Bill Gates – has transformed itself from developing a single advanced reactor design to becoming a hub of innovation in a number of key areas of nuclear science.

It has added to its portfolio projects to manufacture medical isotopes, develop process heat applications and deploy modelling software for use in designing advanced nuclear reactors.

In addition to its work on the Travelling Wave Reactor (TWR), the company has also begun, in cooperation with multiple US partners, to develop a molten chloride salt reactor (MCFR).

The TWR is designed to be capable of using fuel made from depleted uranium, which is currently a waste byproduct of the uranium enrichment process.

The core concept design for a prototype of the TWR has been completed, but not without setbacks.

In 2018 the US government shut down TerraPower’s working relationships in China, driven by a mix of concerns over trade politics and non-proliferation issues.

Chief executive officer Chris Levesque said some had thought the government’s decision would spell the end of the TWR project.

“In China we had a partnership with our counterparts developing the technology and with the regulatory agencies. We were on a schedule that would produce a demonstration reactor within eight years.

“We are now in discussions to re-create the demonstration effort for the TWR here in the US.”

Mr Levesque did not provide a schedule for any TWR demonstration project in the US, but does have a vision of where the company wants to go.

“Our first unit will be a 300-MW demonstration unit built with the support of public/private partnerships. Our intent is to demonstrate that the technology works. To that end we are working on securing a commitment to build it at a DOE national laboratory so that it is licensed by the agency as a research reactor.”

In response to the loss of its partnership with China Mr Levesque said the TWR is “proliferation resistant” and hopes for a “rational policy” from the government so that the company can pursue export sales.

The Challenge From China And Russia

There are challenges ahead from nations that have invested more robustly than the US in advanced nuclear energy technologies. Whereas Congress has appropriated funding for projects in the range of millions of dollars, other nations have pushed forward in key nuclear technology areas with funding levels in the billions.

In 2018, China announced a 20-year programme to spend the equivalent of $3 bn on various designs of molten salt reactors. Earlier this month it was announced that Siberian Chemical Combinehad awarded a $412m contract to Titan-2 for the construction and installation works for the Brest-OD-300 lead-cooled fast neutron reactor facility at its site in Seversk, Russia.

“If we don’t do it, others will,” said Mr Levesque. “Nations like the Canada, the UK and Japan are already making these kinds of investments. Russian and China are way ahead and we have a lot of work to do to catch up.”

As for the MCFR, Mr Levesque said TerraPower knows it can be built. Oak Ridge built molten salt reactors in the 50s and 60s. TerraPower is working with a number of partners on it. The project is funded by a $60m grant from the DOE.

The MCFR project will complement to the TWR programme. It has the potential to be a relatively low-cost reactor that can operate safely in new temperature regimes. This means the technology can do more than generate electricity; it also offers potential in alternative markets, such as process heat and thermal storage.

One of the main areas of focus is to build test loops for the MCFR. TerraPower expects to begin testing in a $20m test loop facility starting in 2020. The team is also scaling up their salt manufacturing process for testing in the loop. Data generated from the test loop will be used to validate thermal hydraulics and safety analysis codes for licensing of the reactor.

TerraPower’s engineers believe that the MCFR could be designed and built as a micro-reactor, a class of nuclear unit generally regarded as being between 2-10 MW. However, Mr Levesque said it is too soon to say what the power level would be for a micro-size MCFR.

TerraPower wants to reduce the time to build a commercial unit from breaking ground to entering revenue service to as little as two-to-three years. Micro-reactors may be appropriate for places that don’t have nuclear energy today like nations in Africa, where they could be deployed in isolated and rural areas.

According to the DOE, the MCFR is a major departure in terms of simplicity, fuel cycle and proliferation characteristics relative to other more-complex nuclear reactor concepts and offers significant safety, performance and economic benefits.

The MCFR has what the industry calls a “walk-away-safe” design that would shut down the reactor without any need for electric pumps to prevent fuel damage. If there is a loss of coolant flow, the fuel salt would expand through the reactor core to passively halt the process and naturally circulate to remove decay heat.

Beyond Nuclear Energy

Two other areas of research for TerraPower centre on decarbonisation of the electrical generation industry by finding ways to replace fossil fuels and on methods to generate and use “process heat”, a general term that refers to the various types of heat transfer techniques used in industrial production. TerraPower plans to produce commercial results in both areas.

“We need to use nuclear heat to replace the energy we get from fossil fuels, such as coal and natural gas, which is used in the processes that make steel and concrete, Mr Levesque said. “We need to reframe our view of what we do with reactors from being merely nuclear steam supply systems to becoming nuclear heat supply systems.”

High on the list of projects TerraPower is working on is developing methods of using process heat to produce high-tech carbon materials from coal.

Carbon fibre produced by this method has unique properties, making the material ideal for applications ranging from aerospace to cars and sporting goods.

Related testing is taking place in the TerraPower lab on alloys and materials that can withstand the intense heat and radiation that occur inside an advanced nuclear reactor.

The challenges are daunting. The temperature inside a light-water reactor reach about 300C, but in the TWR the heat will go up to 500C, and in the MCFR could be as high as 700C.

Spinoffs from the R&D work in this area include building materials and manufacturing methods. TerraPower is also exploring using molten salt as a thermal storage mechanism.

Looking For Rare Medical Isotopes

TerraPower is also working on the production of medical isotopes, supporting medical research by developing advanced radioisotope generators that enable the extraction of rare isotopes that have potentially life-saving qualities.

The company is working on methods to extract Actinium 225 (ACT225) from surplus U233 stored at the Oak Ridge National Laboratory. The isotope could be used in targeted alpha therapy for cancer patients.

The development of new nuclear medicine isotopes shows the value of nuclear science and demonstrates US leadership in this crucial area, Mr Levesque said.

“If we lose this leadership role, because of under investment in nuclear science, it will degrade the work force and diminish the robustness of the supply chain.

“The point is that nuclear science has many collateral benefits. It’s not just about power reactors to make electricity. There is a huge interest by pharmaceutical firms in cost effective production of ACT225.”

This is an edited version of an original article that was originally published in Neutron Bytes. Reproduced with permission.

Date: Wednesday, 18 December 2019
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