ja Nae AECD-3446 Assume U"*~ -66- 235 ; produces 2 neutrons, one escaping Flux at 200 meters = 1 . «2,5 x10 n/cm 42 2 4x(2 x10) = 2.5x10°* x5 x 10! n/om (fast neutrons) .5x10 Using = 0.6 b for ca**(ny) = ca*® (for slow neutrons) N=lon=5x10" x0,6x10-*xn= 9x 10° atoms ca**/gm n=6x10°° x .02 = 3x 107° 40 -dn =.AN= 0.7 at 150 x 24 x 60 _ .9x10° = 6.3 x10° 2x 10° = 3x 10°d/min/gm(Sand) / 10 gmsof fission (at 200 meters) It is apparent from the above results that the presence of cat may be 4 expected in the coral sands within a radius of the crater corresponding to the length of the path of neutrons in the air, LEmteninrertnem ALATA aiteneAnmeee ArenalACURA ARAN A The method used in the separations of calcium from other elements is out- lined below, A simplified method and a more detailed method are included. They | differ in regard to the extent of the scavenging" procedures employed to remove _; fission products. dure II, The first is referred to as Procedure I; the second as Proce- Procedure II gave the lowest values for ca*® /Ca so was regarded as the most satisfactory procedure. ae ;: _. 78 t# PREPARATION OF SAMPLE ' The dry plant material of the coral sand was digested ina kjeldahl flask = with 15 ml of concentrated nitric acid, evaporated almost to dryness, another 15 ml ofnitric acid added and refluxed until all material was in solution; 10 ml hydrochloric acid was then added and the mixture was evaporated until the volume ; was about 2 ml, The material was transferred quantitatively to a 125 ml erlenmey™-; a t se