This Second Edition has been several years in the making. My life-long friend and colleague John Collier died from pancreatic cancer on November 18, 1995. This Second Edition must sadly but proudly serve as a memorial to John and to his intense and firm conviction of the need for nuclear power for the future well-being of the human race on this planet. John Collier’s transparent honesty and humanity provided the best possible witness to the sincerity of this convic­tion. I, too, strongly believe in the ultimate necessity for nuclear power; there will be temporary situations where this need is not so obvious (for instance, the current availability of an excess of natural gas in the United Kingdom), but the long-term situation is clear. It is thus vital to continue research and development in the area and to maintain an adequate technology base. Everything possible must be done to develop public confidence in nuclear power, and the industry should not be averse to considering new concepts which spring from the lessons regarding inherent safety learned in the chemical industry. The main public concern is with the possibility of severe accidents, and the accidents at Three-Mile Island and Chernobyl have naturally served to fuel this fear. The nu­clear industty must recognize this problem of public acceptability and face up to it. Once the long term need for nuclear power is recognised and accepted, solutions can and indeed must be found. However, it is worth pointing out that of all modern industrial plant, even the present generation of nuclear power stations is among the safest. In a properly regulated environment, the present operating nuclear power stations provide a safe and economic means of energy production. However, the nuclear industry needs to give a lot more thought to the sources and consequences of major accidents if, as it seems inevitable to me, nuclear power generation will need to be expanded to meet the growing

energy demands. It is with this as a background that a large amount of the ma­terial in this book is concerned with nuclear accidents and their consequences.

For this Second Edition, the material has been extensively updated and re­vised. In the months before his death, John Collier carried out much of the work in preparation for this, and I would like to place on record my apprecia­tion of his contribution. Perhaps the most important new material is that associ­ated with the Chernobyl accident. This accident happened on April 28, 1986, at a time when the proofs of the First Edition had been produced. A short section was written in the First Edition about the accident but, of course, a full realiza­tion of the sources and consequences of the event was not at that stage possi­ble. We have attempted to rectify this in the current volume. We have also updated the section on the Three Mile Island accident to reflect the continuing developments in understanding and analysis of that event.

Other major modifications in the current volume, with respect to the First Edition, include an updating of the material on Earth’s internal heat generation in Chapter 1, major updating and revision of the general material on severe ac­cidents, and an updating of the material relating to fusion power generation.

I hope that this new edition will be a helpful update for those who pur­chased and used the First Edition and that it will serve to introduce a new gen­eration of readers to nuclear power and its enormous future potential.

G. F. Hewitt, 1996