Indirect detection of dryout in simulated LMFBR fuel assemblies

The method of indirect dryout detection was developed by an examination of the data from THORS Bundle 6A. This was a 19-pin bundle of FFTF configuration. The pin size, wire-wrap size and axial pitch were identical to those in Bundle 9; the major difference between the Bundle 6A and Bundle 9 FPSs was the length of the upper unheated zone, which simulated, in Bundle 6A, the reflector and fission gas plenum in FFTF (1.19 m) and, in Bundle 9, the upper axial blanket and fission gas plenum in CRBR (1.54 m). In addition, Bundle 6A had half-size (0.71 mm) edge channel wire-wraps and a low thermal inertia (0.51 mm thick) duct wall surrounded by calcium silicate insulation in an attempt to flatten the bundle temperature profile