nuclear-news

The myth of the “safety” of new nuclear power designs

Fukushima and the institutional invisibility of nuclear disaster, Ecologist, John Downer 20th December 2014  “………….Complex systems’ ability to keep on surprising

Finally, and most fundamentally, there are many a priori reasons to doubt that any reactor design could be as safe as risk analyses suggest. Observers of complex systems have outlined strong arguments for why critical technologies are inevitably prone to some degree of failure, whatever their design.

The most prominent such argument is Perrow’s Normal Accident Theory (NAT), with its simple but profound probabilistic insight that accidents caused by very improbable confluences of events (that no risk calculation could ever anticipate) are ‘normal’ in systems where there are many opportunities for them to occur.

From this perspective, the ‘we-found-the-flaw-and-fixed-it’ argument is implausible because it offers no way of knowing how many ‘fateful coincidences’ the future might hold.

‘Lesson 1’ of the IAEA’s preliminary report on Fukushima is that the ” … design of nuclear plants should include sufficient protection against infrequent and complex combinations of external events.”

NAT explains why an irreducible number of these ‘complex combinations’ must be forever beyond the reach of formal analysis and managerial control.

A different way of demonstrating much the same conclusion is to point to the fundamental epistemological ambiguity of technological knowledge, and to how the significance of this ambiguity is magnified in complex, safety-critical systems due to the very high levels of certainty these systems require.

Judgements become more significant in this context because they have to be absolutely correct. There is no room for error bars in such calculations . It makes little sense to say that we are 99% certain a reactor will not explode, but only 50% sure that this number is correct.

Perfect safety can never be guaranteed

Viewed from this perspective, it becomes apparent that complex systems are likely to be prone to failures arising from erroneous beliefs that are impossible to predict in advance, which I have elsewhere called ‘Epistemic Accidents’.

This is essentially to say that the ‘we-found-the-flaw-and-fixed-it’ argument cannot guarantee perfect safety because it offers no way of knowing how many new ‘lessons’ the future might hold………

The reliability myth

This is all to say, in essence, that it is misleading to assert that an accident of Fukushima’s scale will not re-occur. For there are credible reasons to believe that the reliability required of reactors is not calculable, and there are credible reasons to believe that the actual reliability of reactors is much lower than is officially calculated.

These limitations are clearly evinced by the actual historical failure rate of nuclear reactors. Even the most rudimentary calculations show that civil nuclear accidents have occurred far more frequently than official reliability assessments have predicted.

The exact numbers vary, depending on how one classifies ‘an accident’ (whether Fukushima counts as one meltdown or three, for example), but Ramana (2011) puts the historical rate of serious meltdowns at 1 in every 3,000 reactor years, while Taebi et al. (2012: 203fn) put it at somewhere between 1 in every 1,300 to 3,600 reactor years.

Either way, the implied reliability is orders of magnitude lower than assessments claim………..http://www.theecologist.org/News/news_analysis/2684383/fukushima_and_the_institutional_invisibility_of_nuclear_disaster.html

December 22, 2014 - Posted by Christina Macpherson | 2 WORLD, safety