Australian news, and some related international items

Why molten salt nuclear reactors really can’t succeed

Beyond Nuclear By M.V. Ramana and Cassandra Jeffery 14 Nov 22

………………………………………………………….Technical Problems

Let us start with the problems with the molten chloride fast reactor. As its name suggests, the reactor uses nuclear materials dissolved in molten chemical salts.

Salt is corrosive — just ask anyone who lives on the coast. So the inside of the reactor will be a chemically corrosive and highly radioactive environment.

No material can perform satisfactorily in such an environment. After reviewing the available studies, all that the U.S. Idaho National Laboratory — a nuclear power booster — could recommend was that “a systematic development program be initiated.”

TerraPower has three different nuclear reactor designs on the books: the Natrium reactor; the molten chloride fast reactor; and the traveling wave reactor.

Given his emphasis on novelty and innovation, one would expect Gates to put his money on reactor designs that are new and likely to succeed. None of these designs have that merit. All of these reactors are based on two old reactor designs vexed with major problems.

Other leading research laboratories like France’s Institut de radioprotection et de sûreté nucléaire (IRSN) and the U.K.’s Nuclear Innovation and Research Office, have concluded that molten salt reactors are problematic. As IRSN put it, “numerous technological challenges remain to be overcome before the construction of an MSR can be considered.”

The historical experience with molten salt reactors has been pretty bleak, to put it mildly. The last one to be built was the Molten Salt Reactor Experiment in Oakridge, Tennessee. It operated intermittently from 1965 to 1969, and operations were interrupted 225 times in those four years; of these interruptions, only 58 were planned.

But it’s not just a matter of molten salt reactors being unreliable or technologically challenged. As Edwin Lyman from the Union of Concerned Scientists has documented at length, the “use of liquid fuel instead of a solid fuel” in molten salt reactors “has significant safety implications for both normal operation and accidents.”

Specifically, the molten nature of the fuel makes it easier for radioactive materials to escape into the atmosphere and be dispersed.

Terrapower’s other two reactor designs are not much better. Both the Travelling Wave Reactor and the Natrium use molten sodium. Another problematic material, molten sodium is used to transport the intense heat produced by the nuclear fission reactions. Again, such reactors have been constructed since the dawn of the nuclear age and with similarly dismal results.

To start with, such reactors have had numerous accidents. The record starts on November 29, 1955 when the Experimental Breeder Reactor (EBR-1) in Idaho had a partial core meltdown.

A decade later, in October 1966, the Fermi-1 demonstration fast reactor in Michigan suffered a partial core meltdown. The shock made its way into the cultural mainstream in the form of a book called We Almost Lost Detroit and a song with the same name by Gil Scott Heron.

In Japan, the Monju reactor suffered a series of accidents and produced almost no electricity, after an expenditure of at least $8.5 billion

The use of molten sodium makes such reactors susceptible to serious fires, because the material burns if exposed to air. Almost all sodium-cooled reactors constructed around the world have experienced sodium leaks, likely because of chemical interactions between sodium and the stainless steel used in various components of the reactor.

Finally, the use of sodium also makes it difficult to maintain and carry out repairs on fast reactors, which then become susceptible to long shutdowns. Having to deal with all these volatile properties and safety concerns naturally drives up the construction costs of fast reactors, rendering them substantially more expensive than common thermal reactors.

Sodium-cooled reactors are also unre­liable, operating at dismally low rates compared to standard reactors. The load factor (the ratio of the amount of electrical energy a power plant has produced to the amount of energy it would have produced had it operated at full capacity) for the Prototype Fast Reactor in the United Kingdom was 27%; France’s Superphenix reactor managed a mere 7.9%.

The typical U.S. reactor operates with a load factor of more than 90%. Sodium- cooled reactors would have to sell their power at higher prices to compensate for the fewer units of electrical energy generated.

“Without innovation, we will not solve climate change,” chanted Gates. But no amount of innovation will change the laws of chemistry or physics. How sodium behaves when it interacts with air or water won’t be affected, even if the sodium is inside a nuclear reactor backed by one of America’s oligarchs.

Innovation will not change the fact that the radioactive wastes produced by the Natrium reactor will remain hazardous for tens of thousands of years……………………………………………….. more


November 14, 2022 - Posted by | Uncategorized

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