Ch. 05 – Nuclear Power 101 (Part 2)

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This article is an excerpt from Chapter five in my new book The Chicken Little Agenda – Debunking Experts’ Lies. You can find out more about the book here, and can order the book from this link. This is the second of five parts for Chapter five that will be presented here sequentially. Read part one here.


Chapter 5

When Nuclear Goes Wrong


Nuclear Power 101

All a nuclear reactor really does is produce a lot of heat, heat that can be used to create steam to drive a turbine to generate electricity. When you create steam by burning biomass such as wood, coal, or oil (or even garbage), you must be careful not to expose yourself directly to the fire: it burns. Ditto for heat produced by nuclear fuel: hot is hot. In addition to heat, nuclear fuel produces beta particles, gamma-rays, and ultimately alpha particles. As we learned earlier, there is nothing particularly mysterious about these. They consist primarily of high-energy electrons (the same kind that flow through conductors), high-energy photons (light), and helium ions. They’re dangerous because they’re energetic and can ionize. A handful of lead pellets poses no danger, but stand in front of a loaded shotgun at your own risk!

A typical reactor is fueled by a mixture containing several forms of refined uranium. This mix is formed into small pellets that are loaded into zirconium tubes. These tubes are then bundled into an assembly called a fuel rod. Fuel rods are placed inside the reactor core, where the uranium mix begins to fission, producing increasing numbers of neutrons until the core goes critical–the reaction becomes self-sustaining. In order to control the reaction process so that the number of neutrons produced equals the number absorbed, control rods made of boron or cadmium are distributed among the fuel rods. These control rods can be adjusted so that the amount of rod material inside the reactor exactly controls the level of neutron production–kind of like a burner knob on a gas stove. Pressurized primary coolant filling the core absorbs the energy released by the fissioning fuel and carries this heat to a heat exchanger, where it is transferred to the secondary coolant. The secondary coolant flashes to steam, which is used to drive the turbine. The steam is condensed back to water in the cooling towers that are characteristic of nuclear power plants.

If something goes wrong at any point, the worst that can happen is the reactor shuts itself off, and it then sits there stewing in its own heat. This can damage internal components of the reactor, but that’s it. A nuclear reactor really is nothing more than a device to boil water into steam to drive a turbine. As with any boiler, the steam it creates is under a lot of pressure.

Can it explode?

Not like a nuclear bomb–that’s impossible. It’s not just unlikely; it is utterly impossible. A nuclear bomb is a runaway chain reaction in fissile material that is tightly contained for several microseconds until the internal pressure builds up sufficiently to cause a gigantic explosion. In a nuclear reactor, the fissile material is not tightly contained. If a runaway chain reaction were somehow to happen, the very worst possible result would be the material gets so hot that it melts and flows around inside the reactor, or perhaps melts out the bottom of a badly designed reactor. That’s it. Once it starts flowing around on the floor it cannot maintain its criticality: no more fission, no more heat, and it all stops. The China Syndrome–the idea that a runaway nuclear reactor could somehow melt through the Earth’s crust and sink right through to China–is a myth. It cannot happen, ever; the physical laws of the universe prevent it.

A reactor is as likely to explode in a non-nuclear way as any other pressurized steam device. If you build it right, it won’t happen. But if something you didn’t plan for goes wrong and it does explode, you get a bunch of hot steam, pieces of pipe and boiler, and–unfortunately–unwanted high-energy emissions as well as scrap that emits alpha and beta particles. This is why reactors operate inside containment buildings. Containment buildings are reinforced concrete structures specifically designed to remain intact should there be an explosion of the pressurized reactor core. When properly designed, they contain the products of the explosion–hence their name.

The Soviets designed the Chernobyl reactors according to the RBMK model. This is an acronym for the Russian reaktor bolshoy moshchnosti kanalniy, which means “reactor (of) large power (of the) channel (type).” These are fueled with slightly enriched natural uranium and are water cooled, and the control rods and reactor core casing are made of graphite. This reactor model has three significant advantages over other models: (1) it does not need a high-pressure primary coolant; (2) it produces on average 10 percent more power; and (3) it costs a lot less to build, in part because its low-pressure design eliminates the need for an expensive containment building–at least in principle. Unfortunately, it has one significant disadvantage. Upon failure, it will go “supercritical.” Like a snowball rolling down a hill, if something goes wrong, it will continue getting worse until the reactor finally melts to a heap of slag and the fissile material is sufficiently separated that it goes sub-critical.

The Soviet designers of the RBMK reactors recognized this potential danger and built five separate fail-safe mechanisms into their design to shut down the reactor in the event any one of several critical failures happened.

So why take this kind of chance? In the old Soviet Union, like everywhere else, it was all about money. In their centrally controlled economy, the lower construction cost and 10 percent additional power productio
n glittered brightly against a backdrop of superior Soviet technology and engineering, even though they had to shut these reactors down four times a year for maintenance. They took a chance, a calculated risk. Sure it was a stupid thing to do, but they did it.
 

© 2006 – Robert G. Williscroft

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