This technical report is intended as a brief description of the free convection problem existing in the various annuli of the SIR Mark A rotating plugs. It is by no means a complete report of the plug "hot tests", but merely records some of the more significant experimental observations and presents a few of the theories and calculations made to explain the observed free convection phenomenon. The general discussion which follows is chronological. Details of analyses are relegated to the Appendix.

This technical report includes (1) World-wide Network (Maps). (2) Fallout of Sr90 at selected sites during August. (3) Comparison of Sr90 collection by gummed paper and pot on the roof of HASL during August. (4) Sr90 contamination of cow's milk in Metropolitan New York. (5) Sr90 content of the upper air during April, May and June. (6) Total activity measurement of the upper air after the Castle Test series. (7) Sr90 content of tap water at HASL before the Castle Test series. (8) Sr90 content of urine and fetal bone in the metropolitan New York area during August.

Abstract: Magnetic susceptibilities per gram atomic weight of elements 92 to 95 in most of their oxidation states were measured at 20°C on 0.1 ml of solution which was 0.005 to 0.09M in heavy element. The values obtained (all paramagnetic) in units × 106 were: U(IV), 3690; Np(VI), 2060; Np(V), 4120; Np(IV), 4000; Pu(IV), 1610; Pu(III), 370; Am(III), 720. The results could be interpreted only on the basis of electronic configurations 5fn, even though susceptibilities were generally lower than the theoretical values and lower than experimental values for corresponding lanthanide 4fn cations. The lower values should be expected as a result of the Stark effect produced by electric fields of anions and of water dipoles. Failure of the Russell‐Saunders approximation to the coupling between electrons may account for some of the error in the theoretical calculations. That the susceptibilities of Pu(III) and Am(III) are manyfold lower than those of Sm(III) and Eu(III), respectively, is attributed to wider multiplet splitting in the actinide atoms.