Terrestrial Energy’s molten-salt reactor gets over one hurdle – but many more to come. Will it be a lemon?

Terrestrial Energy’s molten-salt reactor clears prelicensing review, Globe and Mail, MATTHEW MCCLEARN, APRIL 19, 2023

Nuclear-reactor developer Terrestrial Energy has completed a prelicensing review by the Canadian Nuclear Safety Commission, an early milestone along the road to commercialization of its next-generation product.

The Integral Molten Salt Reactor (IMSR) is the first of its kind to finish the CNSC process known as a vendor design review. Whereas conventional reactors use solid fuel, this novel variety features liquid fuel dissolved in molten salt that’s heated to temperatures above 600 degrees.

The review, which began in 2016, is intended to provide feedback to reactor vendors in the early stages of development, but does not confer a licence to build one. CNSC staff found “no fundamental barriers to licensing,” signalling their willingness to entertain next-generation designs radically different from Canada’s aging fleet of Candu reactors………..

the CNSC’s high-level findings, published Tuesday, highlight the challenges ahead. It called on Terrestrial to provide more information to confirm that the IMSR meets safety requirements. Sensors, monitoring equipment, instrumentation and control systems all need to be further developed……………

” you see a lot of engineering questions that have to be followed up on.” -Akira Tokuhiro, a professor at Ontario Tech’s energy and nuclear engineering department.

Prof. Tokuhiro said answering those questions means Terrestrial (which currently employs about 100 people) will need to grow its engineering staff. NuScale Power, an early developer of small modular reactors (SMR) founded in 2007, stands alone in achieving certification from the U.S. Nuclear Regulatory Commission. It needed 500 staff and US$1-billion to accomplish that, said Prof. Tokuhiro, who previously served as an engineer at NuScale.

“There have been SMR startups – I won’t name names – where the company and investors quit when they got to the point of going from 50 engineers to 500 engineers on payroll,” he said.

Prof. Tokuhiro estimated that fewer than 20 people throughout North America possess deep experience with molten salt technologies, making it difficult to find qualified workers. Moreover, Terrestrial will likely need to build a demonstration unit – another expensive undertaking.

“It has to be a facility that’s quality assured and quality controlled,” he said. “And it has to be able to produce data that the regulator accepts.”……..

nitially developed in the 1950s and 60s, molten salt reactors never operated commercially but have lately enjoyed renewed interest. The U.S. Department of Energy funded two small demonstration projects, and the Canadian government provided tens of millions of dollars to each of Terrestrial and Moltex Energy, another startup, based in New Brunswick, that’s marketing a model known as the Stable Salt Reactor – Wasteburner (SSR-W).

According to a 2021 report about advanced nuclear reactors by the Union of Concerned Scientists, molten salt reactors are “even less mature” than other novel designs such as sodium-cooled and gas-cooled reactors.

That report – entitled Advanced Isn’t Always Better– concluded they were “significantly worse” than traditional light-water reactors in terms of safety and the risk of nuclear proliferation and terrorism, but acknowledged that some molten salt reactors would generate less hazardous waste than conventional models.

“MSR fuels pose unique safety issues,” the report concluded. “Not only is the hot liquid fuel highly corrosive, but it is also difficult to model its complex behaviour as its flows through a reactor system. If cooling is interrupted, the fuel can heat up and destroy an MSR in a matter of minutes.

“Perhaps the most serious safety flaw is that, in contrast to solid-fuelled reactors, MSRs routinely release large quantities of gaseous fission products, which must be trapped and stored.”

The nuclear industry has precious few small modular reactors available for sale today, but is under intense pressure to bring new ones to market quickly to capitalize on an anticipated surge in demand for low-carbon electricity. Yet recent reactors based on conventional technologies took longer than 30 years to develop, license and build, and some ran disastrously overbudget……………………………………. https://www.theglobeandmail.com/business/article-terrestrial-energys-molten-salt-reactor-clears-prelicensing-review/