Japan's Nuclear Disaster - In Layman's Terms

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As an electrical engineer, whose concentration was power generation, I am fascinated (and frightened) at the situation in Japan.

I overheard some folks talking about the disaster yesterday, and couldn’t help but to notice how misinformed they were. 

But, nuclear energy can be confusing, and since the news programs have focused on the doom & gloom more than an explanation of how all this stuff works, I thought I’d help a few of you out.

First the good news.

The Japanese designed their nuclear reactor to withstand an earthquake and it seems as though they were successful. What they didn’t plan on was the flooding and power outages that destroyed the reactor’s cooling water systems.

Now, the bad news.

The nuclear rods (which live in the reactor) use Uranium (the nuclear substance). There is no on-off switch once those rods are put into service. The rods depend on cold water to control their tempature and keep them from overheating.

Since nice clean cooling water isn’t available, the Japanese have brought in dirty ocean water to keep things cool. Unfortunately, the salt in the ocean water, while providing cooling, will contaminate and eventually destroy the rods.

When the rods get too hot, their reactor (container structure) builds pressure. In order to keep the reactor from over-pressuring (blowing up), they opened the chimney to vent off the steam. 

That is not good because the steam contains radioactive material. But, if the pressure is too great, the reactor will blow up. Decisions, decisions!

The venting of steam is the main source of nuclear contamination in the air around Japan (assuming the rods are not broken which is probably not the case or things would have been a lot worse by now).

A nuclear meltdown is when the rods get too hot and break, allowing the Uranium to release in the atmosphere.

Why use nuclear power in the first place?

It is the cheapest method on earth to generate heat which produces electricity.

It works like this. 

When the water cools off the rods, steam is created. The steam is sent to a turbine where electricity is created. The same process is used by all utility companies, but they burn coal, oil, or natural gas to create the heat. 

You only need a little Uranium to create a lot of heat. With coal, oil, and natural gas,  you can stop feeding a furnace or boiler to stop the heat. Uranium takes a long time to burn off. It just keeps on heating until it’s used up.

What’s going to happen next?

The hope in Japan is that they get electricity back to the nuclear power plant soon so they can operate the cooling water system again. Until then, they will have to use the corrosive ocean water in hopes that it buys them enough time before the salt water does it’s damage. 

Hopefully, no rods are destroyed.