An explosive past that still shocks to the very core

If a book has an index, I turn to it straight away to find topics of interest and then read the relevant pages. After this, I peruse all the entries from "A" to "Z" as this reveals the author's prejudices, priorities and competence. A good index is a fast track to the heart of a book and that of its author. Samuel Walker's Three Mile Island has an excellent index.

But the book has omissions. During the past 50 years, there have been three major accidents to nuclear piles or reactors of such a magnitude as to cause, or to threaten, large-scale evacuation of civilian populations. These are: Windscale (UK, October 1957), Three Mile Island (TMI) (US, March 1979) and Chernobyl (Ukraine, April 1986). Windscale threw up similar problems to TMI, particularly relating to whether large-scale evacuations should have been initiated. It is puzzling to find no reference to the accident in Walker's index and no mention of Windscale in a book that promises to put TMI in historical perspective. It is like a book on the Second World War assuming that hostilities started with the attack on Pearl Harbour.

Only three pages of the book are allocated to Chernobyl, and the author places too much emphasis on the weakness of the reactor's containment building as a cause of the release of radioactivity to the environment. He seems not to recognise that Chernobyl, unlike most other "nuclear" accidents (where the damage has been due to physical or chemical reactions or explosions), resulted from a nuclear explosion. Containment could not have restrained it (indeed, the stronger the containment the bigger the eventual bang).

Nevertheless, Walker is an extremely good writer, and this, combined with his unique experience as historian to the US Nuclear Regulatory Commission, and his more recent researches, has placed him in an unrivalled position to tell the TMI story.

Such is his skill that even those who do not specialise in nuclear, or even technical fields, will derive enjoyment from this book. Just as a lacquer artist lays down layer after layer of resin, so Walker describes developments in the unfolding TMI drama by creating layer after layer of detail. I was reminded of Truman Capote's In Cold Blood , in which he describes in infinite detail the murder of a wealthy family and the execution of their murderers. Capote always emphasised the importance of very detailed descriptions.

Capote invented the term "nonfiction novel". So vivid are the images conjured up by Three Mile Island that the term "nonfiction screenplay" would be appropriate. By coincidence a film based on a fictional accident in a nuclear reactor, called The China Syndrome , opened in America 12 days before the accident at TMI. This film, starring Jane Fonda and Michael Douglas, was based on an imaginary accident in which an overheated reactor core melted through the bottom of the reactor's pressure vessel and burrowed through the earth's mantle towards America's antipodes, that is to say, China.

Such were the irradiation levels within TMI after the accident that it was two years before the extent of the damage to its core could be assessed.

The investigators were shocked to find that half the core had melted. That this molten core had not burned its way through the base of the reactor was probably due to the fact that the first fuel to melt had been cooled by the remaining water in the core and formed an insulating barrier, constricting the downwards movement of most of the remaining molten material that had formed subsequently. It was a close-run thing.

Jack Harris is vice-chair of British Pugwash.