New Ideas for Nuclear Reactors

Early nuclear power reactor concepts were generated mainly by a few theoretical physicists during the relatively few quiet hours available in 1942-1945. Reactors were thought of in terms of structures that a plumber could put together. A typical illustration of early thinking is presented. In spite of these primitive beginnings, the basic technical pattern of power reactor development was understood at an early date. 

Estimates of world energy resources are summarized. It is pointed out that the great effort to exploit nuclear energy can be justified only if it is directed toward a full utilization of uranium and thorium. Without breeding, nuclear fuels will only supply energy for a few decades in the future energy-hungry world. 

Recent findings on nuclear reactor stability are discussed and the value of computing machines in theoretical studies is noted. A commentary on current concepts in reactors is presented the flux trap reactor, boiMng reactors, gas-cooUng, and breeders using beryllium or for possible improvement of neutron economy. 

Direct conversion of nuclear heat into electricity is briefly reviewed. Thermocouple batteries and thermionic converters are described and some remarks are made concerning their future de- 

This is the state that I am in now but I will try, nevertheless, to review the very little that I do understand of the progress of the last few years, which seems to me to be truly remarkable, striking, useful, or interesting. I do not claim familiarity with all the amazing developments that took place in this country or abroad and do not even claim that all that is known to me will be presented. Much of what you will hear will not be more than the rambling of an old-timer, but let me start on it anyway. 

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EugeneP. Wigner, New Ideas for Nuclear Reactors , Nuclear Science and Engineering 6, 420, (1959). 

Storage of spent nuclear fuel under dry conditions is not a new idea, but dates back to the end of the fifties. MAGNOX fuel has been stored in diy vaults since 1957. Under dry conditions, there have been no major problems with MAGNOX fuel storage. In-leckage of rain water into the dry vault at Wylfa power station, however, has led to severe corrosion of a few fuel elements. Also spent fuel elements from research reactors and fast reactors have been stored in the U. S., in Jq>an and France for many years without problems. 

In this treatment the subject matter of reactor analysis has been developed with the aid of various mathematical models. The models selected for this purpose are those which have proved to be useful in describing the various neutron phenomena peculiar to nuclear reactors. Emphasis is placed upon detailed presentations of each method in order that the reader becomes sufficiently well equipped to treat new and different situations. In nearly every instance the mathematical treatment has been extended to include the derivation of working formulas, and these are usually followed by numerical examples which display the computational techniques which may be used in application. In a few instances only a formal presentation is supplied, and in these cases the intent is merely to exhibit the principal physical ideas involved. 

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