APR: your source for nuclear news and analysis since April 16, 2010

Monday, April 25, 2011

Chernobyl anniversary... and events today

As we find ourselves, incredibly, at the 25 year anniversary of the accident at Chernobyl, we read that Dmitri Medvedev has been quoted in the press as saying that the Chernobyl accident taught us that we need transparency in the operation of nuclear power plants. Or something to that effect.


The Chernobyl accident taught us the following, in no particular order:

1. Very large, loosely coupled reactor cores can be very dangerously unstable.
2. Safety interlocks and protections should never be overridden.
3. Proper containment for all DBA's must be provided for any plant of any size.
4. Operating entities must never allow test procedure deadlines to subvert a conscious sense of safety-mindedness and questioning attitude.
5. No graphite moderated reactors should be built or operated ever again. The release from the Chernobyl accident in 1986 and the Windscale accident in Great Britain in 1957 are the two highest in history, and both were from graphite moderated reactors of large size. As readers here know the only RBMK-1000 plants still operating are inside the Russian Federation.

We could come up with some further things, but we'll stop here to make this tie-in: You'll notice that NONE of these correlates to events at Fukushima Daiichi. As a matter of fact, they don't correlate to TMI either, and TMI doesn't correlate to Fukushima Daiichi either. This just further points out the irrelevance of all the comparisons being made in the general press as we witness the ongoing situation in Japan and simultaenously arrive at this quarter-century mark for the Chernobyl accident.

More on Chernobyl background to follow this evening.

8:12 PM Eastern Monday 4/25


  1. In some ways, this is a troubling post.
    If there are no lessons learned that read across the most serious nuclear accidents, perhaps it means we have just begun to explore the range of problems this technology poses.
    That would suggest a much bleaker view of the reliability of nuclear installations. Comparing the number of severe accidents with the number of facility years experience would give roughly a 1/10,000 chance of such an accident per year per site.

  2. @netudiant: Actually what it means is that every serious accident is a watershed event, pushing knowledge of every possible relationship to reactor safety to a new level of importance. This is the entire reason behind the complicated and highly advanced fault tree analysis method employed by WASH-1400 and many later RPA works, and by the NRC itself even now. Reliability and safety are industry wide in the United States excellent.

  3. I agree with all points except point number 5. Both pebble bed and prismatic block style HTR's seems to be safe enough and probably safer than LWR's.

    Lesson from Chernobyl regarding graphite is don't put water and graphite together in a reactor.

    Lesson from Windscale is to never operate a reactor in a regime that allows Wigner energy to be built up and don't use air cooling(and even then not much of the graphite burned in Windscale http://www.hse.gov.uk/aboutus/meetings/iacs/nusac/131005/p18.pdf).

  4. Y'all seem to also ignore the use of LFTR reactor technology.


  5. @sassoon: We try to stick to reactor technology on this blog that seems likely to be built; while many other kinds of reactors HAVE been built, tested and even placed in commercial operation it seems perfectly clear from the standpoint of reactor-years of criticality that water cooled, water moderated reactors of either the pressurized water or else the boiling water type will predominate. When one of these other technologies gets closer to being a commercial reality, we'll be sure to report on it here.