Measurements of Κ-Infinity on Zero-Leakage Zoned System (FCA IV)

Abstract

The infinite multiplication factor k^∞ of the test zone composition has been measured for a series of FCA IV assemblies with a central test zone composed to produce a k^∞ value close to unity.
For the experimental determination of k^∞, in which some calculations as well as the reactivity worths of the cell and standard sample measured at the center are necessary, a new method of analysis is presented, and is compared with the current method. The new method provides the theoretical basis for k^∞-experiments. It also simplifies the calculations for analysis.
The FCA IV comprises a series of three assemblies of different test zone compositions representing pure uranium, uranium-sodium and uranium-graphite systems, all of which contain a portion of structural stainless steel. From the analyses made with different cross section sets, it was confirmed that the experimental value of k^∞ could be obtained with an accuracy of ±0.01, and in certain cases, ±0.005, for a zoned system with a central test zone with diameter larger than fifteen times the mean free path.