Nuclear Numbers and Statistics of Disaster










India’s current capacity is 4,385 MW from its 20 nuclear reactors in five locations. It proposes to raise this contribution to 20,000 MW by 2020 and to a further 63,000 MW by 2032 – greater than twelve fold increase in a 21 year period. It will achieve this by an accelerated growth of its civil nuclear program, increasing both the number of sites and also the number of reactors per site. According to the World Nuclear Association, this increase is planned as follows:

Reactors     Power         Date


Under Construction      5       3650 MW          2012

Planned                     18       15,700 MW        2021

‘Firmly’ Proposed          39       45,000 MW        2023


With the increase in number of nuclear reactors comes the associated increase in risk of nuclear incidence. These have been calculated globally, but can also be done for the Indian scenario. Following the methodology given here, the probability of a severe nuclear accident (INES greater than 5) is got by assuming, conservatively, that there have been 4 such nuclear events over 15000 reactor-years for the 433 reactors operating world wide.  We get probability of one severe accident per reactor year as q=4/15000. The mean(m) number of accidents for any reactor number(N) over a duration (y) is then


Mean number of accident, m, expected over a 20 year period (y) is given below; p(>1) is the probability of atleast 1 severe accident in percentage over the same 20 years, following the method outlined in the reference.

For India Reactors           N              m             p>1       Yrs(m=1)


Existing                         20             0.1           9.5%        187

+under contruction        25             0.13         12%         150

+ planned                       43             0.23         20%          87

+ proposed                     82             0.44         36%          45


Thus the chance of a severe nuclear accident in India over a twenty year period is about 10% right now and increases systematically to a substantial risk of 20% in the next 10 years, to high risk of 36% when all those proposed are operating, by 2023. Another way of expressing the same is to calculate, how many years it would take, on average, for one severe nuclear accident in India (i.e. for m=1, y=1/Nq). Currently, on average, we expect to have one such accident per 187 years; this number drops rapidly as we increase our arsenal of nuclear reactors, to an expectancy of once every 45 years, if all the proposed nuclear power reactors were to be built.

There are two caveats to bear in mind. The expert proponents of nuclear power would claim that the new generations of nuclear reactors come with advanced safety provisions and the number used of 4 accidents per total history(15000 reactor years) of all nuclear generators is an overestimate for future generation reactors. True; but accidents like Fukushima take place, not due to lack of safety features, but because of the unforseen that occured. In case of Fukushima, it was the failure of all 13 backup generators. Accidents happen not due to lack of preparation for the imagined, but because the un-imagined also occurs. Statistics, when used in risk analyses, give us an average estimate of most likely events.

Secondly, it is necessary to be aware that the cumulative risks for nuclear reactors grouped together in a particular location, increases the likelihood of simultaneous multiple event as in Fukushima. This has not been included in the calculation.

To summarise, India runs an ever increasing risk of a major nuclear disaster, as it seeks to foolishly exploit the potential of nuclear energy. This, when we have an almost infinite solar potential of 6000 million GWh of energy of every year shining freely upon us!



Arati Chokshi

This post is lifted from I Witness where Arati Chokshi blogs about nuclear and other things.

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