The results of the environmental surveillance program conducted at Site A/Plot M in the Palos Forest Preserve area for Calendar Year 2006 are presented. Based on the results of the 1976-1978 radiological characterization of the site, a determination was made that a surveillance program be established. The characterization study determined that very low levels of hydrogen-3 (as tritiated water) had migrated from the burial ground and were present in two nearby hand-pumped picnic wells. The current surveillance program began in 1980 and consists of sample collection and analysis of surface and subsurface water. The results of the analyses are used to (1) monitor the migration pathway of water from the burial ground (PlotM) to the hand pumped picnic wells, (2) establish if buried radionuclides other than hydrogen-3 have migrated, and (3) monitor the presence of radioactive and chemically hazardous materials in the environment of the area. Hydrogen-3 in the Red GateWoods picnic wells was still detected this year, but the average and maximum concentrations were significantly less than found earlier. Hydrogen-3 continues to be detected in a number of wells, boreholes, dolomite holes, and a surface stream. Analyses since 1984 have indicated the presence of low levels of strontium-90 in …

Passive safety in the Very High Temperature Reactor (VHTR) is strongly dependent on the thermal performance of the Reactor Cavity Cooling System (RCCS). Scaled experiments performed in the Natural Shutdown Test Facility (NSTF) are to provide data for assessing and/or improving computer code models for RCCS phenomena. Design studies and safety analyses that are to support licensing of the VHTR will rely on these models to achieve a high degree of certainty in predicted design heat removal rate. To guide in the selection and development of an appropriate set of experiments a scaling analysis has been performed for the air-cooled RCCS option. The goals were to (1) determine the phenomena that dominate the behavior of the RCCS, (2) determine the general conditions that must be met so that these phenomena and their relative importance are preserved in the experiments, (3) identify constraints specific to the NSTF that potentially might prevent exact similitude, and (4) then to indicate how the experiments can be scaled to prevent distortions in the phenomena of interest. The phenomena identified as important to RCCS operation were also the subject of a recent PIRT study. That work and the present work collectively indicate that the main phenomena …