Sunday, April 3, 2016

The Cornucopia of Nuclear Power

You will remember from chapter 21 that we have two neutrons, on average, emitted whenever a U235 atom undergoes fission - or "splitting." One of these is necessary to fission another atom to keep the chain reaction going. But what happens to all of those second neutrons? Some of them, as mentioned, are absorbed by the structure of the reactor or by the control rods, which slide in and out of the reactor to keep the reaction at - or just very slightly above - the critical point. But others smash into, and are captured by, the plentiful U238 atoms that make up from 95% to 96.5% of the fuel rod contents. When this happens, a truly miraculous thing takes place: This practically worthless material is transformed into one of the most concentrated sources of energy on Earth - or in the universe for that matter - plutonium 239, and element so evil that it was named for the god of the underworld. (Not really, but that's what some would have you believe.) [Plutonium was named in honor of the discovery of the planet Pluto, just as neptunium and uranium were named for Neptune and Uranus.]

This happens in every one of the world's 500 power reactors, plus thousands of research reactors, every day they are in operation. In fact, a sizable fraction (up to about 30%) of electrical energy generated by a power plant comes from this plutonium, which arises as a natural consequence of the uranium fission reaction - without any effort on our part - and supplements the scarce U235 fuel.

Some reactors, however, are designed to intentionally make plutonium. If it is to be used in bombs, it is normally made in a reactor with another modulator - such as the carbon-modulated reactor at Chernobyl. A reactor designed specifically to make only fuel-grade plutonium is called a breeder reactor, since new fuel is "bred" from an almost worthless byproduct of the refining cycle. [Breeder technology seems to be on hold for a couple of reasons: (1) in the prevailing anti-nuclear climate, few entrepreneurs or speculators are willing to make investments in nuclear power for fear of laws that can make their investment instantly worthless; and (2) at the present time there is a glut of plutonium available from the dismantlement of nuclear weapons.]

Are we speculating here on new technology like "fusion" power? Hardly.

The first reactor ever to produce electric power from nuclear energy was a "liquid metal fast breeder reactor" known as the EBR-I. (By the way, liquid metal means that the coolant was not our old friend water, but liquid sodium; fast means that it used "fast neutrons," not the slowed-down, moderated variety.) Designed by physicist Walter Zinn in 1944, his brainchild went critical at 11 am, December 20, 1951 - producing the first steam in history produced by man-made nuclear heat. Like the Manhattan reactor in Chicago and the SLOWPOKE reactor in Canada, EBR-I was not designed to produce electrical power but to prove the concept of fuel breeding (which it did along with its successor, EBR-II). [Declared a national landmark in 1966, the EBR-I is open to the public from mid June to mid September. Located eighteen miles southeast of Arco, Idaho, on Highway 26, visitors must be at least sixteen years old (too much neutron violence?) and U.S. citizens (fear of spies who might steal this technology?).]

The EBR-II had "on the spot reprocessing," which reprocessed 35,000 fuel elements between 1965 and 1969. But the facility was not without problems: the fence around it kept out the coyotes, causing the rabbit population to outbreed the reactor.

Does the ERB-II sound a little familiar? It should since it has another name we used in chapter 21 - the Integral Fast Reactor (IFR).

While many U.S. politicians have never heard of breeder technology, Europeans have. Sadly, "Green" activists there have been successful in shutting them down or keeping them from ever starting up.