NuScale announces achievement of unlimited coping time

At the Nuclear Energy Insider SMR Conference in Columbia, S.C., Dr. Jose Reyes, a co-founder and the Chief Technology Officer of NuScale Power, announced that his team had achieved an impressive design breakthrough.

Two years after the Fukushima event, NuScale is introducing a safety system for our nuclear reactor that does not require DC batteries to place the plant in a safe cool-down condition following an extreme event. This is a revolutionary solution to one of the biggest technical challenges for the current fleet of nuclear energy facilities. Because of our unique design, it allows the NuScale plant to achieve a ‘Triple Crown’ for nuclear plant safety—to safely shut down and self-cool, indefinitely, with no operator action, no AC or DC Power and no additional water.

He and his team approached the design problem from a somewhat unconventional direction. They determined the system configuration required to provide long-term passive cooling of the plant and then selected valves designed to mechanically realign to that configuration during a loss of power event. In design-speak, the valves either “failed shut” or “failed open”, depending on their position in the system. This requirements-driven design process success was made possible because the system has been conceived from the ground up to have as few valves and active components as possible.

For example, the 45 MWe NuScale reactor modules do not use any pumps during power operations; the coolant flow required to move heat from the reactor core to the steam generator is driven solely by natural circulation. Here is how Dr. Reyes describes the design that has resulted from his passive safety-focused approach.

This innovation required taking a look at the station blackout problem in reverse. Rather than requiring power to put the plant in a safe configuration following a station blackout, our engineers found it much simpler and safer to design the ECCS and supporting systems for failsafe operation. That is, the safety valves align in their safest configuration on loss of all plant power. This only works because of the few number of components involved and the fact that the safety systems themselves do not require electrical power to work.

About Rod Adams

13 Responses to “NuScale announces achievement of unlimited coping time”

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  1. Engineer-Poet says:

    Arrange matters so that natural forces do what you want, et voila!

    “Nature, to be commanded, must be obeyed.”

  2. cyril r. says:

    This is one of the most promising small modular reactor systems, the simplicity and inherent safety is easy to see even for those who are not versed in engineering. It’s a giant pool of water. The reactor and containment are submerged in it. There’s no need to bring in any coolant. The coolant is already where it needs to be.

    As a bonus, the water pool provides shielding and seismic support. The relative mass of the entire containment is close to the relative mass of water, so the things will “appear” like a feather to an earthquake.

    They should be able to get a lot of serial manufacturing economy going with that many consecutive units. They just need to find buyers and markets for the first of a kind units, which will be more expensive as they lack economy of scale and don’t yet have serial production cost reduction advantage.

  3. Michael Messner says:

    Thanks for die Article. I have a litte oftopic quwstion about this 45MW Reactor:
    The Power-Rating of 45MW is quite close to the power demand of big container ships, coal an ore-ships and so on. Do you now if there exists planings to use this reactor exactly in this way: For civil naval use?

    • FermiAged says:

      Because the NuScale design uses natural circulation, the core power density is probably lower than a conventional PWR (I haven’t checked this). Additionally, natural circulation is enhanced by the elevation difference between the hot and cold fluids. So I suspect that it may be too large for marine use.

      • Cyril R. says:

        Too large for submarines, for sure.

        But for large ships, there should be no problem. The large pool of water and concrete could act as ballast in the lower hold of the ship. This would work especially well for container ships, where the cargo is on the deck.

  4. Robert Hargraves says:

    pp 281-2 of #thoriumbook describes the clever passive cooling.

  5. Jason C says:

    I think this dispels the myth that the light water reactor can’t be made to be walk-away-safe.

    I’m extremely pleased to hear this news. These are the kind of breakthroughs that are simple and clever enough that easily tear down another myth about nuclear energy.

  6. James Greenidge says:

    Re: “Jason C
    These are the kind of breakthroughs that are simple and clever enough that easily tear down another myth about nuclear energy”.

    True, but the vexing clincher is — who’s going to hear about it??

    James Greenidge
    Queens NY

    • Smilin Joe Fission says:

      And the even more vexing question is – who is going to build it?

      These new reactors are very exciting, I would love to see some real interest in constructing them. I can’t say I blame investors for shying away from nuclear power. Dealing with an inefficient, politically motivated regulatory agency like the NRC adds a lot of risk on return of investment.

  7. Daniel says:

    Addressing the current situation of reactors in Japan, the following pieces of information are worth sharing:

    The 3 and 4 Oi reactors have already signified their compliance to the new safety rules to be enforced July 18th .

    It is my understanding that no other reactors have announced their compliance thus far.

    The Oi 3 and 4 reactors are now operating outside the blessing Japan’s new nuclear regulatory body through a special governmental emergency motion.

    My point is that they seem to be stuck and their international trade situation is getting worse mainly due to their energy imports.

    I think the PM should just apply the same medicine to other reactors than he did for the Oi 3 and 4. Get that special government permission in motion for all reactors no sitting on a fault line and that have been built later than the 1980’s and are deemed safe. It is my understanding that billions of dollars have been spent on safety in the nuclear industry in the the 18 months.

    It is time to get these reactors humming.

  8. Daniel says:

    Rod or any of the elitist members of this board (you know who you are!)

    The new Japan safety rules to be enforced July 18 have been out for a few weeks.

    Some say they are stringents and are likely to make nearly impossible the stat up of reactors before a while. Is that true?

    Others say that 6-8 reactors will be restarted before September.