Three Mile Island ...27 years ago today

Twenty seven years ago, on March 28, 1979, early that morning, about 4 am, some of the main feedwater pumps stopped running in Three Mile Island's Unit Two at Middletown, Pennsylvania on the Susquehanna River. Those pumps were supposed to remove heat from the reactor, which had been on line for only three months. The temperature inside the reactor began to rise, and pressure began to build. A relief valve opened to let off the excess pressure - and then stuck open. The pressure fell below normal levels. (More details / diagrams here)

Another emergency cooling water system was supposed to kick in, it had been tested 2 days before the accident - but because someone forgot to reopen a valve in this backup cooling system after the test, it failed to work properly. Eight minutes later, the valve was opened, and water began to flow through the backup system. ecause a gauge incorrectly said the main system was full of water, the plant operator shut down some pumps and stopped adding water, and the temperature began to rise again.

Before the accident was over, between a third and a half of the reactor fuel had melted. Some radioactive gas was released to the outside. The reactor building's basement was filled with radioactively contaminated water.

Did anyone die ? Will anyone die ?

Studies conducted indicate that the maximum potential offsite radiation exposure likely was 83 millirem. An actual individual located on a nearby island is believed to have received at most 37 millirem. Extensive studies by Federal agencies led to these conclusions and to an estimate that one excess cancer fatality due to the accident could be expected over a 30 year period.

Today, the TMI-2 reactor is permanently shut down and defuelled, the reactor coolant system drained, the radioactive water decontaminated and evaporated, radioactive waste shipped off-site to an appropropriate (?) disposal site, reactor fuel and core debris shipped off-site to a Department of Energy facility, and the remainder of the site is being continously monitored. The owner says it will keep the facility in long-term, monitored storage until the operating license for the TMI-1 plant expires at which time both plants will be decommissioned.

The US Nuclear Regulatory Comission have a very good online Fact sheet about the Accident.

"I think the best way to put it is that there were very poor communications at the time. We weren't able to get clear, accurate information out to the media and the public. ... And at that point the media went to other sources for their information." - Tom Kauffman TMI owners

This single accident, not to mention the Simpson family who live in it's shadow, have have made a massive impact on electricity generation policy, more than any rational argument. No one died, No one will die ... indeed no one was injured.