Of all subjects in the energy industry, few inspire such controversy as nuclear energy.
The facts about the current nuclear fleet are worth revisiting:
- The existing plants were generally very expensive to build. Most of the plants had significant cost overruns – some due to required design changes in the wake of Three Mile Island, some due to construction management incompetence. What was portrayed as “too cheap to meter” turned out to be “too expensive to imagine”.
- Now that the plants are almost fully amortized, their operating costs are very low. The variable cost of nuclear generation is generally less than 2 cents/kwh – lower than pretty much any other baseload (i.e., dependable 24 x 7) generation source.
- Operating performance and reliability have dramatically improved. Whereas capacity factors during the 1980’s were below 60%, the nuclear fleet now runs nearly 90% of the time. Few powerplants run at this level of availability, and it is due to impressive overhauls in operational and management practices during the 1990’s.
- CO2 emissions are nil. Even environmentalists must agree that nuclear power contributes nothing to the climate change issue. Only renewables (such as wind and solar) can also make this claim.
- Wastes from these plants have been an intractable problem. The Yucca Mountain repository has been in the planning stages for over 20 years, with no opening date in sight. A solution like Yucca Mountain (deep underground inert storage) is necessary for our nuclear plants, not so much because of the radioactive products (half-life of 300 years) but because of the “transuranic” heavy metals that are highly toxic for 10,000 years.
- Security concerns are also a major problem. The nuclear cycle used in the current fleet, based on U235 (uranium 235 isotope), inevitably produces weapons-grade material that would be exceedingly dangerous in the wrong hands.
- Public perception of nuclear is skittish. The Three Mile Island incident effectively shut down the nuclear industry in the U.S.; Chernobyl in Europe. People will need a lot of convincing that nuclear powerplant designs are truly “inherently safe”.
Clearly, the existing nuclear plants will run as long as they viably can, but the question remains: is there a viable future for new nuclear plants?
Most observers would say that any new generation of nuclear plants would require a very different design. While uranium generally is not particularly scarce, U235 will become much scarcer in coming decades as its supply is depleted, putting significant upward pressure on the currently low operating cost structure, and thereby making the already dubious total economics of nuclear even more challenging.
This past week, I participated in a very interesting discussion at NASA’s Glenn Research Center of novel advanced nuclear energy designs. These designs address the full set of current concerns about nuclear: economics, environmental, and safety.
There were two main possibilities covered:
- One is to modify the design of the nuclear cycle so that spent fuel is reprocessed rather than merely used once and then stored for disposal. The efforts of the DOE’s Global Nuclear Energy Partnership include the development of Advanced Burner Reactors that will produce energy during fuel reprocessing, return usable fuel, and reduce the amount of toxic and radioactive wastes to be stored. This program is large and long-lived, with billions of dollars of research dollars anticipated through the next 12+ years.
- In my view, the other angle was much more promising: to start from a “clean-sheet” and employ a fission cycle based on thorium. Note that the current nuclear fleet based on U235 was the result of an explicit decision to create a commercial nuclear industry as a direct synergistic pairing with the weapons-production programs of the 1950’s. Thus, the current nuclear approach inextricably poses nasty proliferation and waste problems. On the other hand, the thorium cycle is fundamentally benign. It produces a waste product without any heavy metals that have long-lived toxicity. It does not produce any weapons-quality fission materials. It is a “slow” process, at low temperatures and a negative criticality gradient that ensures it shuts itself down with a failure, rather than a “fast” process (as is the case with U235) that can “run away” in failure mode. And, unlike U235, thorium is incredibly abundant in its supply.
A lot of people think the thorium cycle is too exotic to take seriously. It does sound almost too good to be true, but it ought to be worth a lot more investigation than it seems to be getting — which is approximately none. If success were to be achieved with thorium, many of our energy problems could be solved.