| This project determined the sodium temperature coefficient of reactivity for EBRII using the core configuration from a specific experiment. This involved taking a detailed MCNP model that was prepared for a reactor physics benchmark handbook and converting it into a simplified model. Once the simplified model was constructed, a sodium temperature gradient was applied across the model. The gradient was determined by the flux profile in the reactor, which is assumed to be similar to a cylindrical reactor. This gradient is represented by the sodium density in the core. The sodium temperature gradient has adjusted densities and cross-sections modified by NJOY to calculate the reactivity of the temperature change (Δk). The reactivity change of the core was calculated for two configurations: one was a bulk-to-bulk model, where the sodium temperature remains constant throughout the core, but increases from model to model. The other was a gradient-to-gradient model, where a temperature gradient is applied to the model, and the temperatures of each gradient increase model to model. The bulk-to-bulk model calculation was very uncertain, with a 42% difference from published literature, whereas the gradient-to-gradient model gave a value of -4.00E-04 Δk compared to the published value of -4.15E-04 Δk using a temperature difference of 52°C. The sodium temperature coefficient of reactivity was calculated to be -7.69E-06 Δk/°C |