TerraPower, which is developing the 345 MWe Natrium [tm] sodium cooled fast reactor, has sign a memorandum of understanding (MOU) with the Japan Atomic Energy Agency (JAEA) and two Mitsubishi business units to collaborate on sodium fast reactor technology.  [press release]

The agreement will enable both sides to advance fast-reactor technologies for commercial use.  JAEA, Mitsubishi Heavy Industries, and Mitsubishi FBR Systems will share data and resources related to the development of advanced sodium fast reactor (SFR) technology with TerraPower.

Despite the obvious advantages of sharing technical expertise in this high technology domain, it’s not clear that the two parties are on an equal footing. Also, the planned export of the advanced Natrium reactor has garnered the attention of nonproliferation analysts who worry about unintended use of the fast breeder design to produce weapons grade plutonium.

Scope of the MOU

Japan has extensive experience with R&D efforts to develop sodium-cooled fast reactors dating back to the mid-1980s. TerraPower is interested in technical cooperation with several Japanese entities and intends to work with JAEA and Japanese fast reactor industrial firms for advanced testing of certain components of its Natrium reactor,

Testing of materials and functions for components of the reactor are crucial as input to getting a license from the NRC and in issuing specifications to supply chain firms who will make the components needed to build the reactor.

TerraPower is on a tight schedule under DOE’s Advanced Reactor Demonstration Program (ARDP) to build a first of a kind unit (FOAK) at a site in Wyoming. The 345 MWe  reactors will replace the power generating capacity of an existing coal fired plant.

TerraPower is constructing the Natrium reactor through a public-private partnership with DOE. The department is contributing approximately $2 billion toward licensing and construction costs and TerraPower is matching that total dollar-for-dollar. In the first release of funding TerraPower received $80 million under the cost shared program.

TerraPower’s CEO says he is confident the MOU will succeed. “As a nuclear innovation company, we value mutual learning with the broader global nuclear community and applying this expertise to ongoing efforts,” said Chris Levesque, president and CEO of TerraPower.

“We appreciate the expertise that JAEA will bring to our project, and we are confident that our program will help them as they consider advanced reactors in Japan.”

Likewise, the view from Japan is equally positive. “This cooperation with TerraPower will contribute to further development of the U.S.— Japan cooperation on sodium cooled fast reactors. We believe that It can provide a good opportunity for Japan to advance our SFR technologies toward carbon neutrality,” said Toshio Kodama, president of JAEA.

Levesque noted that while there are many opportunities to share knowledge among U.S. and Japanese partners, there are several differences between the Natrium reactor and previous sodium fast reactors in Japan.

Notably, the Natrium reactor is a commercial power source that will utilize once-through high-assay low-enriched uranium fuel and is not intended for either breeding fissile material or for working in tandem with a reprocessing program. This distinction is very important as fast breeders are often tagged as proliferation risks due to their capability to produce weapons grade plutonium that could fall into the wrong hands.

Japan’s Fractured Fast Reactor Program

It isn’t clear what the scope of the expertise Japan’s team is bringing to the agreement. Mitsubishi’s development of the the Japan Sodium-cooled Fast Reactor (JSFR) was linked in a partnership with the French ASTRID project.  The JSFR was a 750 MWe fast reactor design which would burn MOX fuel. Japan had visions of turning its spent nuclear fuel from its fleet of commercial reactors and having it reprocessed into MOX fuel and burned in fast reactors like the JSFR.

[ IAEA ARIS DBMS Technical Profile – PDF file ]

In September 2019 France pulled the plug on the effort saying it was not commercially viable as a design. Further, Japan’s plans to have a commercial fast reactor by 2050 were probably severely impacted by the French decision to kill the ASTRID effort.

Separarely, the Monju design was a Japanese sodium-cooled fast reactor located near the Tsuruga Nuclear Power Plant, Fukui Prefecture. Construction started in 1986 and the reactor achieved criticality for the first time in April 1994. Monju was a sodium cooled, MOX-fueled, loop-type reactor with three primary coolant loops, designed to produce 280 MWe from 714 MWt.

The reactor has been inoperative for most of the time since it was originally built. It was last operated in 2010 and is now closed. A series of accidents, incidents, and reports of mismanagement of safety inspections all contributed to its demise. It is now in the process of being decommissioned.

The challenges faced by developers of fast reactors in Japan include;

• Reactor design issues and challenges to work with new materials for high heat applications and all for first of a kind systems (FOAK),
• Fuel development, testing and fabrication,
• Regulatory agency safety review and licensing,
• Developing a supply chain for the fuel and the reactor components

Most importantly, the developer of any new nuclear technology in Japan, which has a nuclear adverse electorate due to the Fukushima disaster, must be able to not only be successful in outreach to the public but must also convince a risk adverse publicly traded electric utility that the vendor can deliver one on time, within budget, that it will work as specified, and that it can be operated at a profit within the realities of a regulated market. These challenges come on top of complying with the strict regulatory regime of Japan’s nuclear safety agency.

That’s a tall order and neither of Japan’s two fast reactor projects came close to addressing them with any degree of success. It may be, based on this track record, that Japan may get more benefit from the MOU than TerraPower will get from Japan.

It will be interesting to follow any funded work that develops from it. From TerraPower’s perspective. While the firm hasn’t said as much, the basic principle is that it is always useful to learn from the mistakes of other so that you don’t make them as well. It’s even better if your partners will get the benefit of learning how you solved their problems. Sometimes a little conceptual block busting goes a long way.

There’s a lot that TerraPower brings to the table. The Natrium reactor is based on the GE-Hitachi PRISM reactor which in turn is based on the Integral Fast Reactor (IFR) developed at Argonne West in Idaho and the EBR II also a fast reactor developed at the Idaho lab. As far back as 2010 a task force of subject matter experts concluded that there were no technical barriers to licensing the Integral Fast Reactor. In 2022 the basic design principles of the IFR are incorporated in the ARC-100 which is a 100 MWe SMR being considered by Point Lepreau which is the nuclear utility in New Brunswick, Canada. In summary, the U.S. has a strong technical legacy on fast reactors to share with Japan.

Nonproliferation Concerns

More recently, two noted nuclear nonproliferation experts published an OP ED in a Japanese newspaper raising questions about the export of the Natrium reactor and the possible use of the design as a fast breeder which could produce weapons grade plutonium that could fall into the wrong hands.

Asa lead in to their OPE D, Victor Gilinsky and Henry Sokolski write that the Natrium is to be fueled with uranium enriched to a level below that usable for weapons.

“TerraPower says no ‘reprocessing,’ or chemical separation will be involved, at least at this stage. That would seem to allay security concerns, but there is more to the story.”

According to the authors, the logic of their concerns are;

• Natirum is based on a GE Hitachi Nuclear Energy (GEH) Prism plutonium-fueled fast-breeder design.
• Fast reactors are very flexible in choice of fuel and can switch easily between HALEU and surplus plutonium from reprocessing or other sources..
• TerraPower’s commercial purpose is to produce a product for export to global markets.

It is possible, the authors say, “in fact likely, that international customers will want to run the reactors in the breeder mode, in which case they would have access to copious amounts of plutonium, the stuff of bombs. This creates the classic concern of proliferation, that nuclear weapons would be within easy arm’s reach of many countries. International inspection could not cope with such a situation.”

The authors point out that India and China are investing in fast breeders and have not been transparent about these developments. For instance, China has not been forthcoming about its work on its CFR-660 Fast Breeder reactor.

TerraPower’s Commitment to Nonproliferation

So this is potentially scary stuff and the article raises an important concern. A check of TerraPower’s website indicates the firm is well aware of the issue and has taken steps to address it. The website includes several statements about export of its design and nonproliferation issues.

“Depending upon market conditions, future generations of Natrium reactors could be larger designs, up to the GW scale. Doing so could allow the reactors to take advantage of the benefits of “breed-and-burn” designs that would allow the plants to be refueled with natural unenriched uranium or even depleted uranium. By enabling refueling to occur with these enrichment plant wastes or unenriched materials, the risk of proliferation from exported reactors is further reduced. Inside the reactor core, the reactor does convert some U-238 into a fissile isotope (Pu-239), which it then uses as fuel with uniquely high efficiency before removal. This is the same basic process that occurs in the current generation of light water pressurized reactors, which have been successfully exported around the world.”

“From its beginnings over a decade ago, TerraPower has made reduction of weapons risks a foundational principle. Ethical global exportability is one of the keys to addressing human poverty and climate change. With the participation of retired weapons laboratory directors and their expert personnel, TerraPower laid out the once-through fuel cycle approach that avoids reprocessing, keeps used fuel intact and countable, makes fuel reloads a rare, monitorable event, and eventually reduces need for enrichment plants. The simplified total fuel infrastructure also reduces the opportunities for theft, terrorist actions or accidents during fuel transport by an order of magnitude relative to reprocessing-based approaches.”

There is always a risk of uncontrolled proliferation of weapons grade plutonium, regardless of what reactor it comes from as the world is a dangerous place. The website statement shows that TerraPower has committed to an approach to prevent its efforts from contributing to that problem.

In any case, it will be a few years before TerraPower is ready to deliver on any export deals. That doesn’t take away from the basic concern that some countries can’t be trusted to manage their plutonium stocks in a transparent manner. This means these countries shouldn’t be allowed to participate in nuclear technology export deals from the U.S. that could eventually result is making more of it for them.

This concern was reportedly a contributing factor in the U.S. government’s action in 2019  to cancel TerraPower’s collaborative work with China for development of its traveling wave reactor.

TerraPower has clearly stated its technical approach to avoid having its reactor be a source of surplus plutonium that could be used in weapons. The fact that the technology could potentially be adapted by other countries for this purpose means the issue remains an export control policy issue for the Department of Energy to address sooner rather than later. It is to the agency’s advantage, and TerraPower’s, to craft an policy that allows for exports of the Natrium reactor with appropriate safeguards to countries that are committed to the peaceful use of nuclear energy.

# # #