Tech Talk, Round 4: More Useful Salt Applications

For those of you who read Tuesday’s article on molten salt thermal polar plants, you know that salt can be an effective way to store and release energy over defined periods of time.  Well, today we’re going to look at how molten salt can apply to other sources of energy generation too.

I am a fan of an “all-of-the-above” energy policy, which roughly translated means an energy economy where sources like natural gas and nuclear power play a role alongside renewables to power the nation.  Therefore, I am particularly keen on nuclear power as a possible alternative to coal and oil as a source for base load (that is to say, 24-hr steady) power.  While its upfront costs are expensive, and recent events like the Fukushima Daiichi meltdown in Japan have caused governments to question its safety, nuclear is still the only power that can currently provide baseload power free of carbon emissions, making it a critical component of a low-carbon future for the United States.

One technology is getting a second look at providing nuclear power: salt.  A molten salt reactor (MSR) is a type of nuclear reactor that uses molten salt as a coolant, or even uses the salt itself as a fuel.  While experiments using molten salts in reactor generation have been around since the 1940s, they were derided as too cost-prohibitive to be applied for wide-scale use; however, these days researchers are looking into much more experimentative salt combinations and vastly cheaper alternatives.  Depending on the type of model, the salt either absorbs the heat generated by fuel rods, or creates heat to power turbines which produce electricity. 

This type of reactor has many advantages to the traditional method of nuclear generation:

•         The salt, being denser than water, is able to function as a coolant without the high pressures that water requires in a traditional reactor design.  This results in two distinct advantages:
•            The lower pressures allow the salt to expand naturally, which spaces out the fuel atoms and slows down and stops chain reactions

•       The lower pressure also reduces the risks associated with high-pressure liquids (pipe ruptures, etc.)
•      The salt itself can use nuclear waste from spent fuel rods.  This can provide a use for the barrels of nuclear waste that accumulate from traditional reactor designs.  The generation process in molten salt reactors also reduces the time the waste is radioactive from hundreds of thousands to years to just several hundred years.
•      According to Transatomic (the company working on one version of a molten reactor design), the price per kWh is halved from that of traditional reactor designs.  This could potentially make MSRs twice as cost-efficient as “normal” reactors, assuming the math checks out.
•      The size of the reactors is far smaller than traditional designs can manage:

Source: The Weinberg Foundation

So, let’s recap:  MSRs are smaller, potentially more cost-efficient, can use the waste products of other reactors, and are far, far safer than traditional reactors.  What’s not to like?  Unfortunately, financing for the systems is virtually nonexistent at this time, and the new reactor designs themselves are still just leaving the experimental stage and won’t be ready for deployment for the next few years at least.  But it is encouraging to see that there is enough support for scientists to continue to pursue advancements in this technology.  Hopefully, this technology can revive nuclear power as another viable solution to our energy needs, like it was in the 50s and 60s.