Saturday, March 12, 2011

Nuclear Power Plants

My dear sweet niece asked a question of me. We had been emailing about the Japanese earthquake. Here is what she asked specifically.... "What could trouble with their nuclear plants mean for us??"

Here's what I wrote her.
All nuclear plants are boiling water reactors. They use water to cool the reactors. To cool the reactors, you need power. So, here's the story and the way in which this disaster is occurring.
After the quake the reactors shut down due to the loss of their offsite power due to a malfunction.
That triggered the emergency diesel generators to startup and provide backup power for plant systems. About an hour after the plant shut down, however, the emergency diesel generators stopped, leaving Units 1, 2 and 3 with no power for that all important cooling function.
The nuclear plant brought in mobile generators to restore the power supply, but pressure inside of Unit 1 continued to increase. Which meant it was not being cooled.
Early today the plant said it had lost the ability to control pressure at the No. 1 and 2 reactors.
Now if you followed all of the above, here comes the worrying part.

* In a reactor operating normally, pumps circulate water through the reactor core to keep the rods from overheating. The temperature inside a reactor operating normally is about 550 degrees F (285 C).
* When a reactor shuts, pumps continue to move water over the fuel rods. The electricity to run the pumps usually comes from off-site power supplies brought in by transmission lines.
But, if the power lines fail, the plants have more and other on-site power sources, including backup diesel generators and batteries. Which as we now know are no longer working.

Okay here is the bad part.

An unchecked rise in temperature (no cooling happening) could cause the core to essentially turn into a molten mass that could burn through the reactor walls. This may lead to a release of an unchecked amount of radiation into the containment building that surrounds the reactor. And, thus to the outside. Which is what they are saying this morning has happened.

The outer structure of the building that houses the reactor appears to have blown off, which could suggest the containment building has been breached. (a reactor is usually built within walls and then placed with another set of walls. So walls within walls as a safety measure.)

Earlier a plant operator released what it said was a tiny amount of radioactive steam to reduce the pressure and the danger within the reactor was minimal because tens of thousands of people had already been evacuated from the vicinity. How far is far enough away?

Okay so now you have an unknown amount of radiation leakage which can cause radiation sickness. Below is what that is all about and why the world is worrying.

Radiation sickness is generally associated with an acute (a single large) exposure. Nausea and vomiting are usually the main symptoms. The amount of time between exposure to radiation and the onset of the initial symptoms may be an indicator of how much radiation was absorbed,as symptoms appear sooner with higher doses of exposure. The symptoms of radiation sickness become more serious (and the chance of survival decreases) as the dosage of radiation increases. A few symptom-free days may pass between the appearance of the initial symptoms and the onset of symptoms of more severe illness associated with higher doses of radiation. Nausea and vomiting generally occur within 24–48 hours after exposure to mild doses of radiation. Radiation damage to the intestinal tract lining will cause nausea, bloody vomiting and diarrhea. This occurs when the victim's exposure is 200 rems or more. The radiation will begin to destroy the cells in the body that divide rapidly. These including blood, GI tract, reproductive and hair cells, and harms their DNA and RNA of surviving cells. Headache, fatigue, and weakness are also seen with mild exposure. Moderate exposure is associated with nausea and vomiting beginning within 12–24 hours after exposure. In addition to the symptoms of mild exposure, fever, hair loss, infections, bloody vomit and stools, and poor wound healing are seen with moderate exposure. Nausea and vomiting occur in less than 1 hour after exposure to severe doses of radiation, followed by diarrhea and high fever in addition to the symptoms of lower levels of exposure. Very severe exposure is followed by the onset of nausea and vomiting in less than 30 minutes followed by the appearance of dizziness, disorientation, and low blood pressure in addition to the symptoms of lower levels of exposure. Severe exposure is fatal about 50% of the time.

Then I went on to say why I favored solar power above and beyond nuclear power. Did you know? The American government is talking of building nuclear power plants in California. Isn't there a major fault line located along about the entire coast line called the "San-Andreas" fault?

Does anyone else remember the 1979 movie, "The China Syndrome" with Jane Fonda and Micheal Douglas?

No comments:

Little old me...

My photo
An american yankee up past the 49th parellel.


Blog Archive