Tuesday, January 26, 2010

The ADS Reactor

I do not know much about the ADS (Accelerator-Driven System) reactor, but I have heard it mentioned by a small group of supporters from time to time. I would like to know more about it if possible. The basic principle is one of a sub-critical reactor core that produces free neutrons during the process of spallation, but I am not sure what the spallation process would theoretically be. Finally, I have heard about the ADS reactor reducing the amount of actinides produced but I am not sure what the quantity of leftover material to be disposed of would be compared to that of the traditional LWR.

How does the ADS design stack up to the LFTR and would it be worth pursuing in favor of the LFTR? Does it also have a high enough operating temperature that can be used as process heat for the synthesis of many chemical compounds like the LFTR and VHTR? Where is the research in the development and construction of such a reactor as the ADS? How much would it theoretically cost to build one? Does it have the scaling problems that many reactor designs do?

If anybody knows the details of the ADS reactor, feel free to tell me, as I am eager to learn more about it.


DV8 2XL said...

You might want to read this:


The key quote:

"I therefore reiterate that the ONLY advantage of a subcritical assembly for producing power using either a uranium or thorium cycle seems to me to be the possible psychological advantage of avoiding prompt criticality."

Neurovore said...

Thank you sir, I will take a look.

Luke said...

I'm extremely skeptical about whether the ADS actually does anything worthwhile to justify the extra complexity and cost of such a large, very powerful particle accelerator added to the reactor, particularly when compared against other modern, advanced fission reactors such as IFR, LFTR etc.

There seem to be two main advantages that are claimed:

(1) No fissile start charge is needed, you just run starting from pure U-232 or Th-232.

However, there are ample amounts of HEU, high-grade Pu-239 and U-233 in the world already to provide the startup charges for thousands of IFRs and LFTRs.

Claimed advantage 2: The reactor can't go out of control or melt down, you just turn off the accelerator and it all settles down stably, and fission stops.

Well, so what? No Generation IV reactor such as a IFR, LFTR or PBMR can "melt down", and essentially no reactor can ever explode (with the exception of the RBMK under certain conditions).

The ability to quickly and rapidly shut down criticality and stop the fission chain reaction has been built in to pretty much every reactor ever built... starting from Fermi's squash court pile. (again, excepting those worrisome RBMKs).

Furthermore.... you're talking about a really, really, really powerful proton accelerator, with loads of beam current.

Off the top of my head, the Spallation Neutron Source at ORNL is 2-3 MW beam power, but the accelerator for one of these things needs to be about 12 MW. It's a serious engineering problem just to build the accelerator.

Basically... an ADS is a whole lot more complex than an IFR or LFTR, and a whole lot more expensive, and doesn't actually have anything meaningful to show for it.

Luke said...

Oops, typo.

"pure U-232" in my above post should say U-238.

Neurovore said...

Ah, yes...so the ADS concept is merely a modified Gen III with a few extra bells and whistles from what I have seen so far. Thank you for clearing that up for me.

HOWEVER, the ADS concept might be worth looking into as the Gen IV designs such as the IFR and the LFTR might prove to be politically impossible, particularly with the LFTR because of the fact that it is such a radical departure from traditional reactor designs and trying to get the NRC to license it might prove to be impossible. There is also the fact that the political challenges of setting up a closed-fuel cycle in the US look to be particularly formidable.

I am sorry, but I just have this nagging doubt that many of these technological concepts are ever going to see the light of day here in the US anytime soon simply because of politics and marketing. History is filled with many workable ideas and revolutionary projects but they have simply been shelved by short-sighted supervisors and superiors and forgotten about ever since. Not out of some big conspiracy but simply because the people in charge were too short-sighted or too ignorant to fully understand or care about what they meant at the time.

As it is, I hope that the "Nuclear Renaissance" really does come to pass instead of being buried in a coal-slurry mound by the "clean coal" agenda while choking on the carbon dioxide waste of natural gas peak-generators.

Do not mind my melodrama, just that I am in a bit of a pessimistic mood today.

DV8 2XL said...

The Nuclear Renaissance is happening, but it is centered in India and the Far East at this time. The West will be following this time, not leading.

It will also be GenIII and GenIII+ designs that will lead the way for the first two or three decades. While there are many interesting GenIV ideas they will not get approval or financing to make a difference initially. Keep in mind that the new designs that are well into the approval process, represent huge sunken costs by GE, Westinghouse, et. al. that will need to be recovered before they can move on to new technology.

The only market that may be amenable to penetration by new models is the small reactor sector, which is not being serviced by traditional builders. Here Nuclear Battery, Pebble Bed, and and other small-scale/compact power plants may have a chance.

Even here ADS is unlikely to make much headway because of the huge internal losses systemic to the design.