They’ve announced an international tender for two light-water reactors.
Light-water reactors are simply tanks of ordinary water with uranium rods suspended in them. They are fairly safe; the water increases the reaction rate and is also the coolant, so if you drain the coolant, the reactor physically doesn’t work any more. Three Mile Island was a light-water reactor; Chernobyl was not (it was in fact a bomb factory), and that is the reason why TMI didn’t become Chernobyl.
Light-water reactors are also very proliferation-resistant, and that is why I call on people to support allowing their country’s manufacturers to bid on these plants. Light-water reactors, far from being a proliferation risk, have negative proliferation value. They do this by requiring the services of enrichment plants. An enrichment plant can theoretically produce weapons-grade uranium if constructed and configured correctly (basically, highly-enriched uranium can go critical in some plants that were not designed to produce it), but if that same enrichment plant is entirely occupied with enough low-enriched uranium orders from light-water reactors, it cannot produce any highly-enriched uranium even if it were theoretically capable of doing so. Iran is currently accused of using an enrichment plant for those purposes; enough light-water reactors, with a mandate for the Iranians to provide the fuel, would give the Natanz enrichment facility the proliferation value of a steel foundry.
A common objection to the “negative proliferation value” thesis is plutonium reprocessing. Plutonium reprocessing is similar to an outdated fuel recycling method developed in the 1950s, and is a chemical process used to extract plutonium from spent nuclear fuel for use in nuclear weapons. Attempts to manufacture nuclear weapons out of material from light-water reactors failed, however, since the fuel is left in too long for the plutonium to be useful (the reactor converts the lightest common type of plutonium, which works in bombs, to a slightly heavier type, which does not). There are two other problems with plutonium reprocessing of light-water reactors’ spent fuel:
1. It may be theoretically possible to enrich the plutonium in the lighter weapons-grade material using a uranium enrichment facility. This has never been tried, for a good reason: weapons-grade plutonium has a dramatically lower critical mass than weapons-grade uranium, so introducing it into an enrichment facility could cause a criticality accident, depending on the design, and uranium enrichment facilities are not designed to handle reactor-grade plutonium’s weight distribution. There might be a uranium enrichment plant design where this works, but it’s not likely. If that’s not good enough:
2. The other problem with enriching plutonium from light-water reactors is that light-water reactors use more fissile material than they produce. In other words, the light-water reactor has less plutonium in it than the type of uranium that a uranium enrichment facility concentrates. Thus, it’s just not worth it to try–you might as well make a uranium weapon, and they’re easier to build, too. Be reminded that the plutonium-enrichment scenario also requires that the Natanz plant be taken out of service for an extended length of time to be reconfigured, and would be unavailable to produce low-enriched uranium to feed the light-water reactors while it was doing both the reconfiguring and the plutonium enrichment. So it flunks both tests–the availability requirement, and the physics requirement.
To answer another common objection, no, they could not simply shut down the light-water reactors afterward and reconfigure the facility. The lights would go out–the Iranian grid is too small to absorb the loss of the five to six gigawatts of power that would be generated by enough light-water reactors to use Natanz’s enrichment capacity.
And yes, Israel built its atomic bombs from a light-water research reactor’s plutonium–because they didn’t have an enrichment facility, and the research reactor provides access to the fuel rods while the reactor is running, so that they can be taken out without shutting the reactor down. A light-water power reactor–what the Iranians want to buy–does not allow access to the fuel rods while the reactor is running; in order to take them out before the plutonium inside them is useless for bombs, they would have to shut the reactors down frequently, which they cannot do without causing internationally obvious power outages. And if they did shut them down frequently, they would require more fuel–which Natanz is not capable of providing.
Details, details.
People want to believe that the Iranians, because they are Iranians, will do something bad with these reactors. But done right, they will slow down any speculated Iranian bomb program and quite possibly stop it. The light-water reactor, used in a nuclear power plant (as the Iranians propose), has less than zero military value. Selling the Iranians as many as they want helps everyone involved, including the American, French, Japanese, or Russian companies that get construction experience. There is currently a trade ban that would prevent American companies from selling the Iranians light-water reactors, but I believe that this is an exception that needs to be made; it would enhance American security by killing or dramatically handicapping the Iranians’ capacity to make an atomic bomb. I am of course under no illusions that this will happen; George Bush isn’t thinking that far ahead.
Building an atomic bomb of any type is just a little bit trickier than the political hacks will have you think. Transparently false uranium enrichment allegations led us to the Iraq war. I sure hope it doesn’t lead us to another one.
Filed under International, Iran, New Build, Politics and Regulation, Practical Problems, Proliferation
