Some interesting questions have been put to us about Monday's accident at the Mihama-3 nuclear reactor. In answering a couple of these questions CNIC decided to take the opportunity to provide a little more insight into the place of the Mihama-3 reactor in the Japanese electricity network.
However, we will respond first to a question about evacuation procedures in the case of a serious radiation leak. The question was as follows: "...what, if any plans exist for an attempted evacuation from a Japanese NPP accident/radiation release?"
A Nuclear Disaster Law was enacted in June 2000 in response to the criticality accident at JCO Ltd's uranium processing plant in Tokai Village, Ibaraki Prefecture. Under this law nuclear business operators are mandated to report when a radiation level over 5 micro sieverts per hour is measured at the boundary of their nuclear facilities. When radiation exceeds 500 micro sieverts per hour the Prime Minister will automatically declare a state of emergency and issue evacuation orders. This law requires the establishment of a Nuclear Disaster Response Headquarters headed by the Prime Minister and a local Off-Site Disaster Response Headquarters.
An article about this law and a nuclear disaster drill sponsored by Ibaraki Prefecture and Tokai Village was printed in CNIC's Nuke Info Tokyo No. 86 (Nov/Dec 2001, pp. 1-6). A PDF version of this article can be accessed from the following page:
http://cnic.jp/english/newsletter/index.html
(Note that some of the pictures might not be viewable on old versions of Adobe Acrobat Reader.)
Thankfully in this case an evacuation wasn't necessary. People who read the above article will see that Japan's nuclear disaster response system is not fool proof and does not guarantee the safety of the citizens.
The second question to which we wish to respond is as follows: "... the possibility of Japan shutting down it's commercial reactors. Can they do this & still have enough electricity to keep things running?..."
At this stage the government has said that the pipes in the secondary cooling systems of all of this type of Pressurized Water Reactor (PWR) should be inspected (owned by Kansai, Shikoku, Kyushu and Hokkaido Electric Power Companies). However it has not demanded that all commercial reactors be shut down, or even that all PWRs be shut down. CNIC believes that if all of Japan's 52 nuclear reactors were shut down immediately for inspections, there would probably be a power shortfall. We might get by on some days, but in this season it would be difficult to sustain a sudden shutdown like that.
What if only the 23 PWRs were shut down? In that case there would be enough electricity, but distribution would be a problem. The problem revolves around the fact that Eastern Japan runs on 50 Hertz power supply, whereas Western Japan is 60 Hertz. The maximum amount that can be transferred from one to the other is 900 MW.
The Mihama Nuclear Power Plant is owned by Kansai Electric Power Company (KEPCO). It is located on the Japan Sea Coast and comes under the Western Japan region. All KEPCO's nuclear reactors are PWR, so one would expect that they would be looking for power from other companies. There are some Boiling Water Reactors (BWR) in Western Japan, but the majority are PWR, so there would most likely be a large demand for power to be transferred from the East, where most of the BWR reactors are. If the demand were to exceed 900 MW, then there would be a shortfall in supply.
However, if there was time to prepare for the shutdown and appropriate conservation measures were taken it could be a different matter. For example, in the context of the shutdown of all 17 of Tokyo Electric Power Company's reactors we argued that Tokyo could survive a summer without nuclear power:
http://cnic.jp/english/newsletter/nit96/nit96articles/nit96tepco.html
CNIC and others have developed alternative energy scenarios that show that Japan can do away with nuclear energy and also meet or exceed its Kyoto Protocol commitments for the reduction of CO2 emissions. One such scenario was produced by Citizens' Open Model Project for Alternative and Sustainable Scenarios (http://www.isep.or.jp/shimin-enecho/). (Their home page claims that an English version is coming soon, but for the time being they only have a Japanese version. Anyone wanting details of their scenario would do best to contact them by email.)
Nevertheless, we aren't able to say with confidence that peak electricity demand could be met if there were a sudden shutdown of all reactors, or even of all PWR reactors. But what is the priority here - meeting the peak electricity demand of a society that consumes way beyond what it should do, or preventing a nuclear accident? We'll leave the reader to ponder that question.
Philip White and Hideyuki Ban
CNIC
A list of all Japan's commercial reactors can be found at the following page:
http://cnic.jp/english/data/nucreactors.html
Unfortunately we don't have an English list of all the accidents at these reactors.
Click here for links to more articles about nuclear accidents in Japan
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