I have posted blog stories about start-ups working on nuclear fusion reactors. Now there is a new start-up that is attempting to develop a hybrid fusion-fission power reactor. Mike Cassidy, formerly a Vice President at Alphabet's (formerly Google) X research laboratory and now a consultant for Google, has started a new company called Apollo Fusion. It will not be connected with Alphabet and the founders of Google will not be investors in A.F.
Last Friday, a minimal web page for the new company added a vision statement. The A.F. vision statement said “We're working on revolutionary hybrid reactor technology with fusion power to serve safe, clean, and affordable electricity to everyone. A.F. power plants are designed for zero-consequence outcomes to loss of cooling or loss of control scenarios and they cannot melt down.”
Claims being made for A.F. reactors echo the claims that have been heard from recent exclusively fusion start-ups. Apollo reactors will be inexpensive to construct and operate. They will be competitive with other current sources of electricity. The new reactors will provide scalable energy sources from five megawatts to one thousand megawatts.
Cassidy is working with Ben Longmier who founded a company called Aether Industries which was sold to Apple in 2015. Longmier has a PhD in plasma physics and advanced degrees in physics and nuclear engineering which will provide the expertise that Cassidy will need for his new company.
According to the A.F. website, the new reactors that they are designing are not pure fusion reactors where the power is provided by fusing atomic nuclei. Instead, the A.F. reactors will be hybrid fusion-fission devices. The fusion reaction will be used to generate neutrons for the fission reaction which will actually generate the power. A.F. claims that this approach is more fuel efficient than standard fission power reactors and there is no danger that the reactor will melt down in extreme circumstances.
Nuclear fission power reactors are fueled with either uranium or uranium and plutonium. Their fission reactions dependent on a steady supply of neutrons from disintegrating uranium or uranium and plutonium atoms. For uranium fueled reactors using fuel enriched with U-235, only about one percent of the U-235 is consumed before the fuel is poisoned with reaction by-products and can no longer generate the necessary flux of neutrons. This is extremely wasteful.
In a fusion-fission hybrid reactor such as those proposed by A.F., a fusion reaction is used to generate the neutrons required for the fission reaction. Because the uranium fuel does not have to be the source of the neutrons, most of the U-235 and some of the by-products can be burned. This is much more efficient, cheaper and it produces much less waste. And it allows the use of fusion technology before self-sustaining stand-alone fusion is achieved.
The problem with the A.F. claims is the fact that previous designs for fusion-fission hybrids were estimated to be as expensive as conventional reactors and would only be competitive if they were very large. This contradicts the A.F. claims of low cost and a wide range of potential sizes. A.F. has been very secretive about their design and has not answered these challenges. I hope they have solved the problems because the age of the standard nuclear fission power reactors is drawing to a close.
