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One of the problems with current generation light water reactors is the low thermal efficiency - about 33%. This means 67% of the heat generated by the reactor must be dissipated to the environment, which is why many reactors are loacted near the ocean or other large bodies of water. With its higher thermal efficiency, the MHR can be located in much drier areas. The thermal efficiency is ultimately limited by the laws of thermodynamics, but the MHR can operate much closer to this limit, with efficiencies near 50%.

Lots of non-Japanese in Oarai working in the fishing industry.

Chernobyl was a RBMK reactor with graphite moderator and water cooling. This combination can result in unstable operating conditions, and did with Chernobyl. The MHR has a graphite moderator but uses inert helium as the coolant. It does not require any back up power, even after a complete loss of coolant accident.

I spent most of 2007 working at the HTTR site in Oarai. The parts of Oarai near the coastline were flooded by a 4-m tsunami following the quake. I was saddened to see a video of some of the same streets I used to walk and drive on:

http://www.youtube.com/watch?v=qM6usF56Wpk

It is ironic that Oarai means “big wash.” Fortunately, all of my Japanese friends that I worked with are OK.

Back-to-back Republican heterosexual sex scandals? Not possible.

We shouldn't be too hard on the kid - he no longer has a mother or his family pets.

"I bet Laurie Dhue gives better block parties than J-Lo."

Or Kiran Chetry for that matter.

I agree with your points, but we should also keep in mind that while is is true "the vast majority of Muslims are not terrorists," it is also true that the vast majority of terrorists are Muslims.

Yes, he said Bush was acting like a pussy, which I assume he means Bush was acting like a friendly, domestic kitty cat:<) No big deal to me.

No, Moose is not competent. It's time for Squirrel to take over the investigation.

Through reliable sources, I have been told that Chief Moose is going to announce that Inspector Squirrel has joined the investigation.

I just signed for my good buddy Saddam Hussein.

I took a look at the signature form, and it would be very easy for somebody to submit their names, using their senate e-mail addresses. I think Hannity and Rush were making fools out of themselves by bringing this up today.

Are you kidding? Haven't you seen what happens in Star Trek when they lose containment of the warp core?

The French dropped their fast breeder reactor program (they built two plants) because the technology just doesn't work very well - reactivity excussions they couldn't explain, volatility of sodium coolant, O&M problems, etc. A much better choice for a next-generation nuclear reactor is the passively-safe Gas-Turbine, Modular Helium Reactor (GT-MHR), which can also burn plutonium and transuranic actinides as nuclear fuel, but much more effectively than a fast breeder.

So what! All olympic sports that are decided by judges have been corrupt for decades. Ask Evander Holyfield. Even olympic sports with referees are corrupt. Ask the 1972 U.S. basketball team. Besides, who cares about figure skating.

Letting Torricelli slide while Traficant gets 8 YEARS just doesn't sit well with me, and, IMHO, it's not going to sit well with the majority of Americans. Something here stinks to high heaven.

I agree for the most part with your interpretation of the politics, but there is a little bit of momentum these days to re-visit alternatives to direct disposal of unprocessed LWR spent fuel. In fact, I am presently working on a DOE-funded project to develop transmutation fuels - so even DOE is not putting all of their eggs in one repository.

With regard to MRS, Yucca Mountain (as presently designed) will in effect be an MRS facility for at least the first 100 years or so after it opens. That's because the current design requires the drift tunnels to be actively ventilated for 60 years, otherwise fuel inside the canisters would overheat. Natural ventilation is then relied upon for another 40 years or so. So there are no plans to backfill the tunnels (which I think enhances somewhat long-term proliferation risks). DOE adopted this design because the unventilated, backfilled repository was limited to a very sparse loading of about 4 canisters per acre, because of the decay heat load of the spent fuel and its impact on the structural integrity of the tunnels. When you look at all the extraordinary measures DOE has adopted in order to try and make this repository design work (million dollar canisters, titanium rock/drip shields, adding neutron poison to the canisters, active ventilation, etc.) it becomes increasingly obvious (at least to me) that unprocessed LWR spent fuel is just not the right thing to leave in the ground.

Thanks for the give and take - it's been a good discussion.

You still can't dismiss the possibility that a relatively small, dedicated group of people could successfully remove a canister or two, open the canister (by cutting some welds), remove the fuel rods, and chemically separate the plutonium. This group may or may not have bomb-making capability - if not, they could likely find a market for the plutonium. What is the probability that this scenaio would occur - it's probably very low. But risk is not determined just from the probability of occurrence, but also from the consequences of occurrence. And the potential consequences of a sufficient quantity of weapons-usable plutonium in the wrong hands would be enormous. The two scenarios that I've discussed in this thread (1) repository flooding and (2) long-term proliferation risks (the "plutonium mine") would likely fall into the category of low-probability, high-consequence events. There are also other scenarios (e.g. "repository criticality") that I haven't discussed. But it is often a judgement call to define just how low the probability would be, particularly when you have to consider time periods of tens of thousands of years. A legitimate question from the NRC (or more likely, from organized intervenors) during the licensing process could be along the lines: "You state that the probability for such-and-such scenario is very low and below the design basis. What is the basis for assigning this low probability, and what are the consequences of this scenario if it did occur?" If the consequences are very high, then your stuck with defending an estimate of the probability of occurrence, which can be extremely hard to do when you have to consider time periods of tens of thousands of years.

The bottom line is that unprocessed, light-water reactor spent fuel rods are a very poor waste form for permanent disposal in a geologic repository, with the potential to cause high-consequence scenarios. Yucca Mountain should not be a permanent repository for unprocessed light water reactor spent fuel - rather it should be a centralized, monitored retrievable storage facility. Eventually, the spent fuel should be chemically separated into plutonium, minor actinides, uranium, and fission products. The plutonium and minor actinides should be deep-burned in advanced reactors to eliminate their potential for proliferation. With a deep-burn fuel cycle, the revenues from electricity generated by these advanced reactors should more than pay for the treatment process. The uranium, which constitues 95% of the waste (by weight) can be recycled into the nuclear fuel cycle or disposed as low-level waste. The fission products can be encapsulated within ceramic coatings that have a corrosion resistance of 100,000 years or more (based on mineral analogues). When the NRC or the intervenors ask their questions, the answer will be along the lines: "We have considered these scenarios. Because of the fact that we have separated and destroyed the fissile material, and because the remaining waste is encapsulated by ceramic materials, the consequences of these scenarios are negligible."