reactor design idea?
I am new to this forum -- winding up here after some web searching. Not sure if I've come to the right place...
After the Fukushima disaster, I did a little research on Chernobyl, and found that the two events had something big in common -- lack of power to run cooling pumps.
I am by no means a nuclear engineer, but I wonder if the overall design could be changed a bit to make these reactors much safer in the event of a power failure or other disruption... I have an idea that I'd like to share with an engineer, just to see if it seems plausible.
Any suggestions of people I might talk to? Thanks.
(I made the original post on
(I made the original post on this thread...)
Well, I'm not sure that passive or convective cooling is really what I had in mind. It's more like this:
If coolant pumps are critically important, it seems excessively risky to rely on electric power and/or backup generators to power them. Especially when you're sitting on a massive power source in the reactor already. We should consider using steam-driven coolant circulation pumps.
When the reactor gets hot, more steam and pressure are produced, which drives the steam-powered pumps harder, and delivers more coolant. More heat leads to more cooling.
In the absence of external commands (i.e. electric controls) the reactor should stabilize itself at an equilibrium of relatively low activity.
Only when the electric controls are functioning, would it be possible to bring the reactor above this baseline equilibrium for the production of electricity. And in the event of some natural disaster or power failure, the reactor self-regulates back to the equilibrium state.
In other words -- coolant pumps keep working whenever the reactor is making heat, regardless of external circumstances.
Won't work
And in the event of some natural disaster or power failure, the reactor self-regulates back to the equilibrium state.
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If you have a natural disaster like Fukushima that drops the power lines and leaves the reactor without the grid as a load, you can't run the reactor at the power level it had before the event.
If you lower reactor power, then the build-up of Xenon-135 due to the Xenon transient will shut the reactor down for you. If if you attempt to counteract this tendency; you get an unstable situation ala' Chernobyl.
WOW
Can run reactor at any power level, but there ARE limits on generator power. Flashing steam, in a closed loop, is OK.
Just need a few, smaller steam turbine generators and/or some other fluid turbine generation, such as propane. This will generatet electricity at lower temperatures. CCLC
WOW
Steam-driven pumps
GE power reactors like Fukushima already have steam-driven coolant pumps. It's call HPCI - High Pressure Coolant Injection.
However, with only shutdown heat, you don't have enough pumping capacity.
The operators at Chernobyl attempted to keep the reactor critical at low power in order to see if they could power steam-driven pumps, and ran afoul of the Xenon transient that every reactor has when it shutsdown or reduces power, and the result is history.
Bad idea.
Reactors for grid.
We don't need them. Period.
Reactors are useful for bomb material, Medical isotopes, Research. Please let's take them out of private hands and general use.
Thank You.
Minus One
Let's get rid of them as bomb material too!
Former reactor designer
Any suggestions of people I might talk to? Thanks.
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What's your idea? The first few years of my career I worked for Argonne National Lab in nuclear reactor design. I worked for Dr. Charles Till on the design of the Integral Fast Reactor:
http://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/till.html
The IFR has inherent shutdown mechanisms, and after shutdown, it can be adequately cooled by its liquid sodium coolant driven only by natural convection. ( As long as you have gravity, you will have natural convection.)
The new reactor designs are
The new reactor designs are significantly safer. These Generation 4 reactors use passive cooling to help cool the reactor once it is shutdown. The passive cooling does not require active pumps, so no electricity is needed. The natural circulation of the steam cools the reactor.
And what happens with a
And what happens with a Generation 4 reactor when there is a loss-of-coolant accident and the steam boils off the water?
That is the idea. The water
That is the idea. The water turns to steam which circulates around. That natural circulation cools the steam back to water and the process repeats. They can sustain passive cooling for a week I think.
What about the coolant all
What about the coolant all boiling off through a leak (loss-of-coolant)? Imagine your kettle or cooking pot boiling dry. What happens to the Generation 4 reactor then?
It is considered a beyond
It is considered a beyond design basis evident. You would need to lose coolant through the primary(loss of coolant) and also have a hole in primary and secondary containment. That would be a very rare event.
that was the essence of the
that was the essence of the idea I had... thanks.
natural convection
that was the essence of the idea I had... thanks.
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Yes - natural convection has been thought of and incorporated into more advanced designs. Unfortunately, since the USA hasn't been building nuclear power plants in the last few decades, there's been no opportunity to incorporate these additional safety technologies into the fleet of power plants.
So are you saying the
So are you saying the existing USA reactors are unsafe? If they are already safe why would convection cooling be of any benefit?
Safety is not binary
So are you saying the existing USA reactors are unsafe? If they are already safe why would convection cooling be of any benefit?
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Safety is not a binary choice. It's not a case of there only being two states "safe" ( 100% safe ) or "unsafe" ( 0% safe ).
There's a whole continuum of safety. Are airliners safe? We tend to think they are when the odds of having a crash are something like 1:10 Million.
However, what if the odds were 1:100 Million. or 1:1 Billion? or 1:10 Billion....
Even if something is "safe", you can make it even "safer".
Present nuclear power plants are safe, but using natural convection cooling makes them even safer.
Got it, Fukushima is safe,
Got it, Fukushima is safe, right, thanks for clarifying.
Or, is it not safe because it is actually no longer a nuclear power plant, and not a 'present nuclear power plant'?
It seems to instead be a total disaster and a pile of extremely toxic material now that no one knows what to do with, and that will soon be killing people by giving them cancer.