Like what you've read?

On Line Opinion is the only Australian site where you get all sides of the story. We don't
charge, but we need your support. Here’s how you can help.

  • Advertise

    We have a monthly audience of 70,000 and advertising packages from $200 a month.

  • Volunteer

    We always need commissioning editors and sub-editors.

  • Contribute

    Got something to say? Submit an essay.


 The National Forum   Donate   Your Account   On Line Opinion   Forum   Blogs   Polling   About   
On Line Opinion logo ON LINE OPINION - Australia's e-journal of social and political debate

Subscribe!
Subscribe





On Line Opinion is a not-for-profit publication and relies on the generosity of its sponsors, editors and contributors. If you would like to help, contact us.
___________

Syndicate
RSS/XML


RSS 2.0

What is going on at Fukushima?

By Tom Quirk - posted Wednesday, 6 April 2011


There have been reports on the reactor crisis in Japan that range on the John Cleese scale of alerts all the way from “No worries” to the never before used extreme ”The Saturday barbie is cancelled”. So perhaps one should start with some facts and build up to the uncertainties.

Reactor Types:

There are boiling light water reactors, pressure light water reactors and graphite based reactors, as at Chernobyl, that all require enriched uranium. On the other hand, CANDU heavy water reactors use natural uranium as a fuel. The distinction for CANDU is heavy water enriched in deuterium. Graphite power reactors were operated within the Soviet Bloc but not elsewhere as there has always been a concern about neutron damage to graphite moderators, that is, the elements in the reactor that slow down the neutrons. Most power reactors are boiling or pressure water reactors where the water is both moderator and coolant.

Advertisement

The fuels used are either low enriched uranium, about 2.7% U-235, or mixed oxide fuel that uses weapons grade plutonium along with natural or depleted uranium. The uranium, as an oxide is formed into ceramic pellets that are put in a tube of zirconium alloy. Zirconium is a good conductor of heat and transparent to reactor neutrons. However if the fuel rods reach a temperature of around 1,000 0C then water will oxidize the zirconium releasing hydrogen. Normally a boiling water reactor operates with a water temperature of around 300 0C at a pressure of 75 atmospheres.

Radioactive iodine with a half life of 8 days and cesium with a half life of 30 years are products from the fission of U-235. Iodine, if it falls to the ground is taken into cows’ milk and if drunk by us will concentrate in the thyroid. While cesium has a much longer life, it is not assessed as a significant hazard.

Japanese Nuclear Power Plants

Japan has 55 power reactors and Fukushima is one of the top fifteen nuclear power plants in the world.

There were 6 operating nuclear reactors at Fukushima for a total of 4,700 MW of electric power.. This is about 75% of the capacity in the Latrobe valley. There are a further 2 reactors totaling 2,800 MW of electric power under construction. The first reactor commenced commercial operation in 1971 and number 6 reactor came on line in 1979. The reactors are all boiling water designs supplied by General Electric for units 1, 2 and 6, by Toshiba for units 3 and 5 and by Hitachi for unit 4.

The Fukushima reactors are all “Generation II” reactors. The reactor is within a steel pressure vessel contained within a second concrete structure. The reactor sits at the top of the building and the concrete structure includes chambers beneath the steel vessel that can be used for emergency venting of steam from the pressure vessel. In addition, the spent fuel rods are kept in adjacent cooling pools at the same level as the reactor.

Advertisement

Past Nuclear Accidents

Before discussing what has or may have happened it is useful to look at the two major events at nuclear power plants, Three Mile Island and Chernobyl.

On March 28, 1979 a light water reactor at the Three Mile Island nuclear power plant suffered a partial meltdown. Within weeks attorneys filed law suits against Metropolitan Edison Company (a subsidiary of General Public Utilities) on behalf of all manner of businesses and residents within 25 miles of the plant. Over 2,000 personal injury claims were filed, with plaintiffs claiming a variety of health injuries caused by gamma radiation exposure. The Pennsylvania district court quickly consolidated the claims into ten test cases. Over the next 15 years, the cases went to the Supreme Court and back, and through various district and appeals courts. Finally, in June 1996 district court judge Sylvia Rambo dismissed the lawsuit granting summary judgment in favor of the defendants. There was no significant radiation exposure beyond the limits of the power station. An estimate of the likely number of deaths from radiation induced cancer is less than one.

  1. Pages:
  2. Page 1
  3. 2
  4. All


Discuss in our Forums

See what other readers are saying about this article!

Click here to read & post comments.

38 posts so far.

Share this:
reddit this reddit thisbookmark with del.icio.us Del.icio.usdigg thisseed newsvineSeed NewsvineStumbleUpon StumbleUponsubmit to propellerkwoff it

About the Author

Tom Quirk is a director of Sementis Limited a privately owned biotechnology company. He has been Chairman of the Victorian Rail Track Corporation, Deputy Chairman of Victorian Energy Networks and Peptech Limited as well as a director of Biota Holdings Limited He worked in CRA Ltd setting up new businesses and also for James D. Wolfensohn in a New York based venture capital fund. He spent 15 years as an experimental research physicist, university lecturer and Oxford don.

Other articles by this Author

All articles by Tom Quirk

Creative Commons LicenseThis work is licensed under a Creative Commons License.

Article Tools
Comment 38 comments
Print Printable version
Subscribe Subscribe
Email Email a friend
Advertisement

About Us Search Discuss Feedback Legals Privacy