Abstract
This work presents a method of determining the lumped heat-transfer coefficient and the temperature coefficients of reactivity of a nuclear reactor. No knowledge of the component temperatures is required. The method is thus particularly attractive in systems where temperatures cannot be monitored, or where uncertainties in temperature variations can produce large errors in experimental menults.
A mathematical model is developed for the reactor, which is assumed to consist of lumped fuel, moderator, and reflector regions. Simplified forms of this model are also developed: a two-region model for fuel and moderator, and a one-region model for fuel only. The equations for these models are expressed as functions of the feedback response of the reactor. The high frequency feedback response is normally a function of only the fuel temperature coefficient of reactivity and the heat-transfer capability from the fuel. The experimental high frequency response characteristic can thus be applied to the one-region mathematical model to determine the fuel reactivity coefficient and the heat-transfer capability. In a similar manner, the experimental medium frequency response of the reactor can permit a determination of the fuel and moderator feedback coefficients, and the low frequency response the determination of the reflector coefficients.
The model was applied to a swimming pool reactor, with the frequency response measured with a pile oscillator over the frequency range 0·03 to 150 rad./sec. Excellent agreement was obtained between the mathematical model and the experimental response over the entire frequency range.