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Ensuring a secure future for nuclear power

by SuperiorInvest

The world needs to expand global nuclear power generation to help curb global carbon emissions. This conclusion is based on many models and projections that suggest that renewables cannot do it on their own.

But there is one important caveat. We simply cannot have major nuclear incidents like the ones that happened in Chernobyl, Ukraine and Fukushima, Japan. These are what I consider to be low-risk but high-consequence events.

There have been several serious incidents in the history of nuclear power. But nuclear power plants have the unique potential to permanently displace entire cities in the event of a serious accident.

The Chernobyl accident eventually displaced about 350,000 people. Thousands of square kilometers were set aside as an uninhabited closed zone around the Chernobyl nuclear power plant. Many people were also displaced by the Fukushima accident, although not as many as Chernobyl.

If nuclear power is to realize its potential for reducing carbon emissions, we must ensure that such accidents do not occur again.

Building safer nuclear power plants

I recently had the opportunity to talk about these issues with Dr. Kathryn Huff, Deputy Secretary of the Department of Energy’s Office of Nuclear Energy.

Dr. Huff explained that passive safety systems are key to ensuring that in the event of an accident, workers can exit the nuclear power plant and it shuts down in a safe state.

There is an important distinction to be made here. The public can expect nuclear designs to be fail-safe, but there are many reasons why this metric will never be achieved. In short, you cannot protect yourself from all possible incidents that could occur. So we try to mitigate the possible consequences and implement fail-safe designs.

A simple example of a fail-safe design is an electrical fuse. It will not prevent an incident where too much current is trying to flow through the fuse. But if this happens, the connection melts and stops the flow of electricity – a fail-safe condition. Neither Chernobyl nor Fukushima were fail-safe structures.

But how can such fail-safe designs be implemented? Dr. Huff pointed to two examples.

The first is the new pressurized water reactor (PWR) AP1000® from Westinghouse. The problem at Fukushima was that after the shutdown, energy needed to be available to circulate water to cool the reactor. When power was lost, the ability to cool the reactor core was gone.

The new APR reactor relies on natural forces such as gravity, natural circulation and compressed gases to circulate water and prevent the core and containment from overheating.

In addition to passive cooling, there have been innovations in the development of new generation fuel types that are accident resistant. For example, tristructural isotropic (TRISO) particulate fuel it is made of a fuel core of uranium, carbon and oxygen. Each particle is its own capture system thanks to the triple layers. TRISO particles can withstand much higher temperatures than current nuclear fuels and simply cannot melt in a reactor.

Dr. Huff said that by the end of the decade, a demo of an advanced pebble-bed reactor filled with TRISO particles will be online.

These two innovations can ensure that future nuclear power plants never experience a major accident. However, there are other issues that need to be addressed, such as nuclear waste disposal. I will cover this – as well as what the US is doing to promote nuclear power – in Part II of my interview with Dr. Huff.

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