Yet, once-used nuclear fuel doesn’t get recycled in spite of its tremendous residual energy potential and economic value. The US policy was decided in the Carter Administration where the recycling of spent nuclear fuel was prohibited by executive order, largely as non-proliferation gesture. A nearly completed recycling facility was abandoned in South Carolina at a cost of almost a billion dollars. The nuclear plant operators didn’t really care since the once-thru cycle was cheaper and less hassle given prevailing yellowcake prices post-Cartel.

After considerable study, the government reached the obvious conclusion; if you don’t recycle it, then bury it. With the passage of the Nuclear Waste Policy Act of 1982 (NWPA), a waste “fee” of 1 mil per kW-hr of nuclear electricity was charged to the end-user and assigned to a Nuclear Waste Trust Fund. Like excess funds from the Social Security payroll taxes, the cash not spent goes into the general Treasury while the Trust Fund gets government promissory notes to hold until the day comes when burial costs exceed the fee cash flow. Then the general taxpayer will have to pony up the cash to redeem the promissory notes to pay actual construction costs. As of first quarter, 2005, the federal government has collected over $23 billion. Of that $6.3 billion has been spent (2), so far, on detailed engineering and scientific studies, an exploratory tunnel, a number of tests, and a subsidy to the State of Nevada. That leaves almost $17 billion in collected cash spent elsewhere in the Congressional budgets over the years. A cynic would call it a hidden tax.

The nuclear plant owners were happy to see the passage of the NWPA since the US government promised to take title to their spent fuel while the hidden tax they were asked to collect didn’t make much difference in their power pricing. One mil per kW-hr equals $1.00 per MW-hr where market prices may float around $50 so nuclear’s competitive position was not materially affected. The best part was a promise to begin taking physical possession of the spent fuel by 1998 (3). Of course, that date came and went with the rods still in the power plant’s spent fuel pools where they remain to this day (or in dry casks bought by the utility and resting in the plant’s backyard.) The utilities, of course, eventually sued and won some of the additional storage costs back.

After a show of considering alternate sites for the burial spot, Yucca Mountain in Nevada was chosen by Act of Congress. While Yucca Mountain has numerous technical attractions such as trivial rainfall, excellent rock, and existing federal land ownership, our cynic might note that the fact that Nevada has the smallest Congressional delegation of any of the considered sites may have had something to do with it. Located adjacent to the Nuclear Weapon Test site, Yucca Mountain overlooks Jackass Flats, site of the nuclear rocket engine test in the ‘60s which is in turn just over the hill from Yucca Flat, site of almost 1,000 nuclear weapon tests, both underground and atmospheric. It’s difficult to imagine a more God-forsaken spot on the North American continent. ANWR is Maui in comparison.

The design of Yucca Mountain has been a challenging problem. The original design called for a 10,000 year retention criterion but a recent court ruling allowed the EPA to extend their radiation dose rules out to one million years. The spent rods are to be enclosed in high quality stainless steel inner casks with two inch walls, all within an outer cash made of an exotic material called Alloy C-22, essentially stainless steel without the weakest link - steel. The casks will be located tunnels 1,000 feet underground. To prevent dripping water from falling on the C-22 casks, a titanium “shed” will cover each cask. (4) A wag could call it the most expensive brick outhouse since the Great Pyramids. A cynic might say the challenge was in how the bureaucracy could spend all that money. Frankly, it has been a very impressive effort by some of our country’s best minds.

The official 2001 estimate was that it will cost $57.5 billion in 2000 dollars when it’s all over (5) but it had jumped from $45.8 billion just two years before. Many in the industry and the opposition privately expect the final price to reach $100 billion and I agree. To be fair, about 10% of the waste tonnage at Yucca Mountain will not be from civilian nuclear power plants but from Cold War defense programs. The general taxpayer, rather than the utility ratepayer, will have to kick in for that portion of the bill.

So why does it cost so much and why must we design for so long? The answer to both questions is one word – “actinides.” A spent fuel rod has four constituents. First is zirconium cladding, a metal much like titanium, neither radioactive nor toxic. Inside the cladding are the fission products and “heavy metal.” Fresh fission products are intensely radioactive, so much so, that each fuel assembly can put out as much heat as 118 one hundred watt light bulbs at time of burial, a decade after its removal from the reactor. Twenty minutes leaning up against a fully packed cask will get you your 50/50 death dose of radiation. (i.e. 500 rems). The GOOD news about fission fragments is that they decay fairly rapidly so that only a short retention time is required for their containment. Plus, they decay to stable, non-radioactive elements.

The heavy metal is the real meat of the design and there we find the challenge and the opportunity. Most of the heavy metal is uranium and plutonium, both recyclable back into new fuel for the reactors. By my back of the envelope calculation, the current 70,000 metric tonne Yucca Mountain content could make ten times the electricity, if recycled, as could the Strategic Petroleum Reserve if SPR were burned to make electricity (unlikely, I realize.) That’s a TRILLION dollars worth of electricity at wholesale and enough to fuel the current US nuke fleet for 10 years or, given the additional reactors, make all our electricity for 4 years. (6)

The real bad actors at Yucca Mountain, the stuff that drives the long-term maximum rock temperature and ultimate radiation doses out beyond 10,000 years, are the actinides. These are the radioisotopes beyond plutonium on the Periodic Table - Americium, Californium, Curium, etc, formed after a neutron is absorbed by uranium-238 without fissioning and the resultant plutonium in turn absorbs further neutrons without fissioning. Surprisingly, one of these, Americium-241, has saved thousands of lives as the active ingredient in home smoke detectors that no doubt grace your bedroom.

The solution, just like the solution to municipal waste, is segregate, recycle, and incinerate. Reprocessing spent nuclear fuel is an established technology, dating back to the Manhattan Project. France, Russia, Japan, and Great Britain all do it. In the classic process, one chops up the fuel rods, dissolves them in nitric acid and separates the uranium/plutonium in one liquid stream, the fission products in another, and the actinides in a third (the zirconium cladding “husks” don’t dissolve.) The uranium is still relatively enriched in uranium-235 compared to natural, so is “blended up” to reactor fuel standards. The plutonium is mixed with uranium to become what’s known as “mixed oxide fuel” or MOX. MOX is every bit as good as reactor fuel as what our plants run on today, albeit a bit more hassle for the utilities to handle.

The economics of MOX fuel are difficult to calculate today. In the US, about half of our reactor fuel comes from scrapped Russian nuclear warheads, fueling perhaps 10% of all US electricity. This uranium source should continue to enter the market for some years and will probably expand to the burning of plutonium warheads too. Yellowcake, raw commercial-grade uranium oxide, has recently jumped in price due to rumored bidding from China anticipating a big expansion of their civilian nuclear power program but the market price could easily decline, with the opening of new mines. Remember, yellowcake is a commodity and hence is subject to the price volatility typical of commodities. It is fair to say that reactor fuel using recycled MOX will be more costly than the current once-through fuel cycle, but not significantly so for the end price of nuclear electricity. But then, I’m charged extra for my recycling program for home waste too. According to the American Enterprise Institute, household recycling costs 35% to 55% more than simple disposal (7) yet we do it in almost every urban area.

The interesting part of this proposal is how to handle the actinides, once separated. The market for home smoke detectors is already well served, so the particular Americium-241 to be buried at Yucca will need another fix. While actinides are not fissile enough in current plant designs to be considered fuel, one can design and build a reactor where they would come pretty close. In other words, we could take the pesky, expensive actinide wastes and make electricity from them!

I’ve come to realize over the years that few people appreciate the beauty of molten metal cooling as much as we nuclear engineers do. Sure, it sounds scary, but heat transfer between a hot metal fuel rod and molten metal coolant is exceptionally high, higher than any other practical method. We nuclear engineers like our reactor cores small and compact and intense, the better to lower capital costs – liquid metal cooling is a great way to do that. Of course, the designers of gasoline engines for Porsche, Mercedes, SAAB, and Corvettes appreciate liquid metal cooling too since engine exhaust valves for these power plants are hollow and half filled with molten sodium, the better to transfer excessive heat in the exhaust valve metal to the engine’s cooling systems.

The actinide “burners” would be fast reactors, using the neutrons fresh and unslowed from the initial fissioning process. What is needed, given the nuclear physics of actinides, is a very “hard” neutron spectrum (hard = fast), the harder the better. Cooling would be molten lead (in most designs, molten fluoride salts in some) avoiding the issues we saw with molten sodium in fast breeder reactor designs in the past. Useful heat would be produced as a result of the burning that could make perhaps 100 to 200 MW of electricity as a by-product (8).

Of course, no one has built an specific actinide burner yet but our researchers think it not an impossible task. Preliminary designs have been sketched out in several countries, as have preliminary fuel cycles and fuel designs. In some concepts, alternate reprocessing methods are combined with actinide burners to increase proliferation resistance.

So how does Harry Reid save us all this money? As senior senator from Nevada and Senate Minority Leader, he has fought Yucca Mountain for years and shows no sign of rolling over any time soon. So what if we suggested an alternative? With Senator Reid’s leadership, Congress could instruct the US nuclear power industry to adopt recycling. We could still use Yucca Mountain but it would then contain a tenth of the volume of waste that would be toxic for a thousandth of the time, in a waste form (fission products in pyrex glass matrix) ten times more resistant than spent fuel rods. For a rational constituent, that should sound like a great deal, making Mr. Reid a hero plus aiding America’s energy independence by substantially increasing our domestic nuclear fuel supplies.

The basic price tag for recycling of the 63,000 tons of spent civilian fuel planned for Yucca Mountain would include roughly $10 billion for reprocessing plants and fission product glassification facilities and another $10 billion for R&D and construction of perhaps two actinide burners (my preliminary estimates based on a wide review of the literature, some of it proprietary). Fuel fabrication plants for MOX fuel are coming in any case, just to deal with Cold War plutonium surpluses - $5 billion would more than do in case one wanted to assign that cost too. Yucca Mountain would still need some work but the design and construction effort required to complete it as a depository for fission products only would be trivial given the billions we’ve already spent on characterizing the site. In fact, one could open up the option of walking away from Yucca Mountain altogether and finding a new site, given that the design requirements would be so much easier – but that would be a political question!

One serious objection that we’d be sure to hear from former President Carter and the environmentalist groups is that we’d now making plutonium an article of commerce. The risks for diversion into the hands of nuclear terrorists will increase, above that poised by our allies’ recycle programs. My counter argument is that with current plans, we’re really building a future plutonium ore body. In 300 years or so, someone could tunnel into Yucca Mountain and pull out the spent fuel rods with their bare hands (9), chemically separate out the reactor grade plutonium and manufacture a creditable nuclear explosive. Note that there are 25 nuclear waste repositories planned world-wide. The answer to this objection is really, aren’t we just pushing the nuclear proliferation issue off on unborn generations by building Yucca Mountain? Why not deal with it now with recycle and actinide burners?

So on one hand we have the anticipated $100 billion to complete Yucca Mountain against $20 billion for reprocessing plants and actinide burners. We’ll call utility costs for burning MOX and new MOX fabrication plants a wash against future yellowcake savings. If Harry Reid wanted to get behind this, there are surely sensible Republicans and Democrats that would support it too. We’d save money, solve the nuclear waste issue, and increase domestic electricity fuel supply.

What’s not to like?

References:

(1) http://www.epa.gov/epaoswer/non-hw/muncpl/msw99.htm
 

(2) http://www.ocrwm.doe.gov/pm/budget/monsum_feb2005.pdf
 

(3) http://www.nei.org/index.asp?catnum=2&catid=63
 

(4) Yucca Mountain Science and Engineering Report, DOE/RW-0539, May 2001
 

(5) http://www.ocrwm.doe.gov/pm/pdf/tslccr1.pdf
 

(6) Roughly 63,000 tons of spent fuel at 3% fissile content (uranium + plutonium) fueling a 1,250 MW reactor that uses 1 ton of fissile material a year. Total electric consumption per EIA for 2003 at $50/MW-hr wholesale.
 

(7) http://www.taemag.com/issues/articleid.17823/article_detail.asp
 

(8) Most preliminary estimates call for a pair of 300 MW(th) reactors which should yield 100 MWe each. Note that lead cooled reactors (or a lead-bismuth mixture) have been used by the Russian Navy for submarine propulsion.
 

(9) http://www.nuc.berkeley.edu/thyd/peterson/papers/Repository.pdf

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