A Measurement of the Effective Delayed Neutron Fraction of the Westinghouse Idaho Nuclear Company Slab Tank Assembly Using Rossi-α Techniques

The effective delayed neutron fraction of a solution reactor fueled with highly enriched ura-nyl nitrate was measured using two Rossi-a techniques: the “slope” method and the Nelson number method. The average value of the effective delayed neutron fraction was measured to be 0.0147 ± 13%, which is significantly higher than the calculated value of0.009. The discrepancy between the measured and the calculated value is not understood at this time, but it is suspected that the majority of the bias is associated with the measurement of the intrinsic neutron source strength.