303 S. HISAMATSU and M. SAKANOQUE 3 & 3 E * o a n nw = “1 NN “ 7 a = ™ w oO w E. Escape peak nm ~ B.G. Buck - S ea un > 5 GGG Y wOnTONK TOORN Oe wo een 5 a £ ¢ 25 MMmBDONKOO LR man c 2 oa ioe} Wid wi \] 3 oO AL Aas 1 © | uo Vi A he ot Myctl Ae Pi a BON © 5 oO 3g | eo ! Now © t3raT | Vr: oti 7 wo OO KO x monk L i | ~ ©nD uv U 522 uJ 3 s we 5 Oe ey a > < z pat o 5 E - ud 104} g sao eK 3Jatnltoava a oe 8 SF7DZzADAD=A KEE 3 > c ground to : J ok adi!a ade \ 6 ea m oo "|! i tere i atts... 107} 44 4br L 9 + a 100 . 200 300 2 400 _ 500 4 600 1 700 ‘ goo 900 Channel Fic. 2. Low-energy gamma- and X-ray spectrum on “Bikini Ash”, ; . “A . plutonium isotopes and *“'Am, respectively. Cenmpte 4a One of these tracers, "Gd, a 3.18-MeV al- PAP 2am ayy pha-emitter, was prepared by the reaction of Pup. 4ny "Gd, and it was confirmed that the Gd/Am ratio did not change during the same radiochemical procedure as used in the present work. Details of the carrier-free "Gd preparation (Ko76) and the usefulness of “Gd as tracer were previously reported elsewhere ; “Np ——> Pu (1569). The concentration of ' the **Pu tracer was calibrated with a stan- Pu solution supplied from monia to the supernatant, the coprecipitation of plutonium and other clements with hydroxide precipitates (iron hydroxide, etc.) was carricd out. When only a little amount of precipitate was obtained, it was spiked with Ata about 5mg Fe* carrier. The precipitate was ft i + 9.709 | [ba mip ey" . 1 BIKINI tO MOL. +9 my the Radioactivity Centre, Amersham, England. Each sample was treated with 8m hot hydrochloric acid. By adding aqueous am- je yy . 0 uw. ey ~ | AIOE 50 thm Stee eee | we Go . FIG. 3. Analytical resulls for : t om =f; di {- t ' ir senting ' “f (Sa72). The other tracer nuclide, ?“Pu, was produced by the reaction of 7”Nply #) dard | ' : 1 . . 1 _— - Pekew asbhtFuk ur pus morul ‘9 ‘ ; RONGELAP ATOLL | ne 2199240 ° ‘ 167 16 zi Pu and . Am in “Bikini Ash’ and marine sediment samples. The open circles indicate sampling points and the exposure point of the “Sth FPukuryu-Maro.” The bold fine, set by the U.S. Navy, was the boundary of the area prohibited for navigation at the time of the nuclear bomhtest in (984.