Small Modular Reactors

A small modular reactor (SMR) design has been approved by the NRC. You can read about it here:

https://singularityhub.com/2022/08/05/the-first-small-modular-nuclear-reactor-design-was-just-approved-by-us-regulators/

Apparently it has some "novel" safety features:

The SMRs come with novel safety features designed to prevent the kind of disasters that have hardened public opinion against nuclear power.

For a start, control rods used to stop the fission reaction by encasing the fuel rods are held above the reactor’s core by an electric motor. This means that in the case of a power outage they will automatically drop into position under the force of gravity. The entire reactor is also bathed in a water pool, which can draw away excess heat in case of emergency. Also, by using smaller amounts of fuel, the total amount of heat produced is greatly reduced.

I worked in the US military and civilian power programs for over 20 years. I was certified as a US Navy nuclear engineer and as a GE-trained Senior Reactor Operator. I wrote design basis documents for the GE SBWR and did dozens of technical evaluations for numerous nuclear power plants.

Frankly I see nothing very novel about this new design, at least as described in the above report. All control rod systems have an allegedly foolproof way to shutdown the reactor. Yes, gravity exerts a constant force, but it may not overcome the force from a steam leak or other forces present during an accident. Many designs encapsulate equipment in water, but the real issue is the size and resiliency of the associated heat sink. And while limiting the total amount of heat may seem worthwhile, safety limits are based on limiting the maximum temperature reached in the fuel rods during an accident. That limit could be exceeded even with a relatively small heat load.

The three major accidents most people recognize were related more to poorly conceived, intentional choices than to faulty design:

• The TMI accident was exascerbated when operators turned off cooling systems after misreading the state of the plant;
• The Chernobyl accident occurred after plant operators foolishly turned off safety systems to conduct a reactor test without understanding the consequences; and
• The Fukushima accident occured because the plant was built at sea level. A higher elevation for the site was rejected because of the additional cost and difficulty of construction.

The biggest problems I saw as a technical evaluator stemmed from the fact that time after time, even the best engineers and operators made mistakes which were not detected until it was too late. There will be mistakes made with the new design(s), too. You can count on it.

A successful design and a well constructed plant are the result of intelligent leadership. Sadly, such a thing is sorely lacking in US industries today. Just look at the last few nuclear projects, and you'll see what I mean. Unless that changes, and I don't know how it can, I suggest we avoid nuclear power altogether.