Fast reactors Doppler effect

This is essentially the same result obtained and used in the early fast reactor Doppler effect calculations (6,15). There are differences involving the ratio E,/Sp, a number near unity. The present development is slightly more accurate. 

The J function of thermal reactor Doppler effect theory is also extremely useful to fast reactor theory. It is given in our notation by... 

The Doppler Effect in Fast Reactors R. B. Nicholson and E. A. Fischer... 

The investigation of safety and more particularly of severe accident conditions is important for accelerator driven systems (ADS). Subcritical ADS could be of particular interest for the actinide transmutation from the safety point of view, because fast reactors with Neptunium, Americium and Curium have a much smaller fraction of delayed neutron emitters (compared to the common fuels and U), a small Doppler effect and possibly a positive coolant void coefficient. This poses a particular problem of control since the fraction of delayed neutrons is essential for the operation of a nuclear reactor in the critical state. In addition, the IRC presented in the past a review of accelerator-driven sub-critical systems with emphasis on safety related power transients followed by a survey of thorium specific problems of chemistry, metallurgy, fuel fabrication and proliferation resistance. 

H. Feshbach, G. Goertzel, and H. Yamuchi, Estimation of Doppler effect in fast reactors. Nuclear Science and Engineering vol. 1 (1956) pp. 4-20. 

C. Comparison of Doppler Effect for Fast and Thermal Reactor. 113... 

D. The Early Development of Doppler Effect Theory in Fast Reactors. 114... 

The Doppler effect in thermal reactors (13, 14) has been developed to the point where calculations are considered to be highly reliable. The reliability has not yet been established for fast reactors. Authors have typically attached uncertainties of 50% to their calculated Doppler temperature coefficients of reactivity (6, 12k, 121). However, we believe that, with improvements in the theory of recent years, the theoretical methods are actually substantially more accurate than 50%, and the main remaining errors lie in the experimental data for resonance parameters and calculation of the group fluxes and adjoints. It is the main purpose of this chapter to present a derivation and discussion of the currently available theoretical techniques for fast reactors. ... 

We do not give a complete review of the work done on Doppler effect over the past 10 years. This has been very well done in a recent paper by Nordheim (13), who reviews the Doppler effect in both thermal and fast reactors. Instead, we attempt to present a unified development of the... 

The first serious attempt to calculate the Doppler effect for a fast reactor was by Goertzel and Feshbach (4, 12j, 15), who developed a technique that is basically equivalent to that presented here for the high end of the Doppler effect energy region. Their work was directed toward obtaining an estimate for the effect in EBR-1, which exhibited what at that time was an unexplainable instability, which was at least in part due to the existence of a prompt positive temperature coefficient of reactivity (16). Since this reactor was fueled with fully enriched uranium, it was conceivable that the positive coefficient was due to Doppler broadening of... 

As interest in large fast reactors began to accelerate after 1960, the importance of Doppler effect became more and more evident, and several groups began to make more careful calculations and re-examine the theoretical basis of the methods. At least for homogeneous systems, this phase of redevelopment of the theory is nearly complete, and there are... 

THE DOPPLER EFFECT IN FAST REACTORS 149 The temperature derivative of (65) is (without the sum over sequences)... 

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