DOUBLE RUBBLE: Partial Disclosure

The above summary report, December 14, 1970, is partial disclosure relating to the photograph DOUBLE RUBBLE, TOIL AND TROUBLE.

For clarity the following key sentence and the related footnote is copied here: It appears likely that ignition of the Zircaloy grids led to high rates of heat input* at the elevation one foot above (and below) midplane and this caused overtemperature and failure of the heaters.

*The ratio of surface area to heat capacity for a Zircaloy grid is approximately 15 times that of a heater rod, hence Zircaloy-steam reactions can lead (to) steeper temperature ramps in the vicinity of a Zircaloy grid.