B&W mPower Modular Nuclear Reactor

The Babcock and Wilcox modular reactor, mPower, has something of a head start due to B&W's long relationship with the US military. B&W has demonstrated its ability to build safe, reliable, durable nuclear reactors. The mPower design incorporates a number of innovations that should make civilian nuclear power safer, more reliable, quicker to implement, and far more scalable.

The central innovation here that we believe makes this whole thing work is to have an integral nuclear steam supply system (NSSS) that we can manufacture within our own vertically integrated supply chain.
When you look at traditional light water reactors in the fleet—pressurized water reactors (PWRs)—it’s a pretty complicated nuclear steam supply system. You have a reactor, you have a pressurizer and typically you have four steam generators all in their own heavy pressure vessel, all connected by pretty big primary system piping and large reactor coolant pumps. That’s a complicated structure that certainly cannot be fabricated in a factory and shipped to the site.

By integrating all of those components into a single module, not only do we create a scenario whereby we can manufacture that within a factory and ship it in total to a site—which takes the entire first year of a typical nuclear plant construction cycle off the critical path and allows you to do it in parallel with other activities—but obviously you gain all of the efficiencies you have in a factory setting relative to a stick-built field construction effort.

That’s the explicit advantage, but implicit in all of that is passive safety. Because there is no primary system coolant piping and no large nozzles or penetrations on the reactor vessel, there is no possibility for a large break loss-of-coolant accident, what’s called a large break LOCA. The only pipes that go in and out of the reactor are the secondary side, the feedwater and then the steam coming back out, which isn’t connected to the primary system at all, and then there is a small cleanup line and some emergency injection line. All of those are relatively small penetrations.

The technology that paved the way conceptually for passive safety is the Westinghouse AP1000. But because the AP1000 is still a large plant with external steam generators, they have large break LOCAs, their core gets uncovered during an accident scenario. Even though their safety injection system is passive in the sense that there are no active high pressure injection pumps, it is still pretty complicated and needs to be rather robust because it has to deal with the reactor core that gets uncovered.

With our design, the core never gets uncovered under any postulated design-basis accident. That is an incredible step forward from a safety perspective and greatly simplifies and reduces the challenge that you need to address with an emergency core cooling system. That is a separate result of the innovative approach with an integral NSSS.

Because you can have a much simpler passive safety system, that takes cost out of the nuclear island on the safety side. When you shrink down a plant, typically you’re dealing with negative economies of scale but here we have changed the game and reformulated the overall concept of the nuclear island in a way that allows us to be cost-competitive relative to a large gigawatt-class plant. _PowerGenWorldwide

There is much more information at the link above, including details about improved safety and security, information about the convenient size of the reactor -- rail car sized -- etc. mPower can be shipped anywhere, and will be installed underground. The reactor core can be changed out all at one time, for speedier changeover.

More information should be forthcoming soon. Since B&W is an established manufacturer with a good track record, it is likely to be treated a bit differently by the NRC than startups such as NuScale and Hyperion.

But expect environmental groups to do everything possible to slow the approval and licensing of all forms of newer, safer, more economical nuclear power. Environmental organisations are in it for the power and the cash. They see clean and abundant energy as a threat to their power, and will fight it tooth and nail, using any subterfuge readily at hand.