Monday, May 7, 2018

Energy: "Thorium salt reactor experiments resume after 40 years"

From New Atlas:
Scientists at the Nuclear Research and Consultancy Group (NRG) the Netherlands, are looking back to the 1970s to meet the energy needs of the future. For the first time since 1976, the NRG team is conducting experiments in thorium molten salt reactor technology that could lead to cleaner, safer nuclear reactors capable of supplying energy on a global scale.

In a world marked by strong political pressure to create a carbon-neutral economy, nuclear energy seems like an ideal alternative. Despite their reputation, nuclear reactors have a remarkable record for reliability, produce carbon emissions that are lower than even wind and solar when construction, operation, and life cycles are taken into account, and have the lowest fatality rate per watt of any competitor.

However, nuclear power does suffer from four major drawbacks. First, the uranium needed to power reactors is rare and expensive to process. Second, the technology to produce nuclear fuel can also be adapted to create weapons. Third, there is the danger in older reactor designs of an unlikely, but frightening catastrophic meltdown. And fourth, no one has come up with a long-term nuclear waste disposal strategy that is acceptable to everyone.
One way of overcoming these issues is to replace the uranium and the plutonium derived from it with a different fissile material. Since the 1940s, the most attractive alternative has been thorium. Unlike uranium, thorium is abundant and widespread, it doesn't require the sort of elaborate enrichment process that uranium needs, and it isn't easily made into bombs. In addition, thorium reactors have an inherently safe design that shuts down if the reaction goes out of control, and the radioactive waste products from thorium are relatively short lived – becoming harmless in only a matter of centuries.
The main obstacle is that thorium can't achieve critical mass on its own. If you take enough uranium that's been refined to fuel grade and stack it together, the amount of neutron radiation released will start a chain reaction that will cause the uranium atoms to split in a self-sustaining process. Unfortunately, thorium can't do this, so thorium fuel must be mixed with uranium or subjected to an outside neutron source to start the reaction cycle....MUCH MORE