Document Release of CSAM 99-140 to DNFSB for Review, October 17, 2018
The data sheet on HFE-7200 from 3M is included in attachment 2. Unfortunately, at this time, the Criticality Safety Group cannot allow the replacement of TCE by HFE-7200 for the reasons discussed below. The moderating and reflecting properties of HFE-7200 were compared to trichloroethylene (TCE) and water. The results of several calculations are presented in attachment 1 and indicate that water is a far superior moderator than either HFE-7200 or TCE, but HFE-7200 results in significantly higher reactivity than TCE. The criticality safety evaluation for machining (CSM1020) credited the usage of TCE and this material was included in the Monte Carlo calculations to determine the reactivity of the upset conditions. Unfortunately, since the results of these calculations are relatively high, it cannot be determined without significant re-evaluation whether the replacement of conservatisms were employed in CSM1020 to simplify the calculations, it is likely that a re-evaluation considering less conservative models would allow the approval of HFE-7200. The Criticality Safety Group will include HFE-7200 when the evaluation for machining is upgraded to higher mass limits (with shape control).