Last year, an exciting development occurred for advanced nuclear power: Molten salt reactor (MSR) investigation won funding from the Technology Strategy Board. The Alvin Weinberg Foundation welcomed the development, writing “MSRs could be a game-changing way of producing clean electricity, so this is great news for all who support the revival of clean energy R&D to tackle climate change”. The bid was led by Jasper Tomlinson, Professor Trevor Griffiths, and project manager Rory O’Sullivan, who together planned to produce the UKs first rigorous study of the feasibility of a pilot-scale MSR. And the results are now in.
The review not only argues the necessity of nuclear power, but seeks to answer the questions of how to pursue it. Current nuclear deployment appears, the study states, to be locked into old solid-fuelled technology, with little innovation since the 1970s and even less development of advanced options such as MSRs. Previous reviews of MSRs, such as the Generation VI Forum January 2014 Report, have concluded that the technology is one of the furthest from commercial deployment. However much has been achieved in the MSR world in recent years, and taking into account the latest developments this publication concludes that the time is now right for a “commitment to an agenda to proceed with a molten salt reactor programme”. Six different reactor options were assessed in the MSR review:
- Fibre Energy’s Liquid Fluoride Thorium Reactor (LFTR),
- Martingale’s ThorCon,
- Moltex Energy’s Stable Salt Reactor
- Seaborg Technologies – Seaborg Waste Burner
- Terrestrial Energy’s Integral MSR
- Transatomic Power Reactor
All six display the advantageous characteristics of using molten salt as fuel and coolant including safety, less waste, higher thermal efficiency, fuel cycle flexibility (including the ability to use up the plutonium stockpile as fuel) and co-generation opportunities afforded by the high temperatures at which the reactors operate. Despite finding advantages in all the reactor designs, the review concludes that The Stable Salt Reactor, the design proposed by Moltex Energy, is the best option to pursue. The Stable Salt Reactor is a fast spectrum pool type reactor but its unique characteristic compared with the other designs is that the fuel is static.
Most Molten Salt reactors involve the highly radioactive liquid being actively pumped through a heat exchanger while the Moltex design encases the radioactive molten salt (a fraction of spent nuclear fuel mixed with sodium chloride to reduce its melting point) within metal tubes, similar to the fuel rods in traditional reactors. The flow of molten salt in the tubes is entirely by natural convection with no moving parts involved meaning no possibility of pump failure. The pool of coolant is another molten salt that makes the reactor intrinsically safe since any leakage of radioactive fuel is mixed and diluted in the large pool of coolant. Unlike all other molten salt reactor designs, this design in not a derivative of the Molten Salt Reactor Experiment developed at Oak Ridge National Laboratory (where MSR designs were initially developed in the 1960s) and is instead a truly 21st century design. Along with a whole host of benefits the Stable Salt Reactor is designed so that all components can be constructed in segments and assembled at any given site. This modular design is far simpler and more affordable than todays reactors and makes deployment all the more attractive.
The report concludes that this UK designed reactor, “due to its relative simplicity and relatively few and low technical hurdles, is the most suitable configuration for immediate pilot scale development in the UK”. Regardless of the specific reactor, the report also outlines the general advantages to the UK of pursuing an MSR program. Britain’s role as a leader in nuclear power has been declining since the 1970s with no new plant built since Sizewell-B in 1987. Currently, the UK has a non-existent nuclear R&D spend compared with other countries. However, the advantages of redeveloping our nuclear strength are many, including manufacturing growth, employment, energy security, reduced waste insecurity, positive contribution to carbon reduction targets, and technology export potential. With clear advantages, and a promising design to develop in the Stable Salt Reactor, it must be hoped the government, in the midst of scrapping subsidies and despairing over delays at Hinkley C, see the prosperity an MSR program could bring.