tact . 2355 Oost bute at ko, ney a on tne u.rect pe ond ier to ° to flow oetween teem. True > Nave Leetau cal "he same when cre 3) INO CONS Gerat 4. . or The relation between Gr cocieacts..t. The as hoe FL e . 1toe . a se , fat St dael ult 2 WeeKs ZL ugh both sections would ovav dures two weeks was taken sn sea water and the radioactive fallout .* 6s stuared at the position 150 km east of Be. Ve Hee ey aing omoust) Marcio when her crews reo .nizetoona /olust particles ta, cyt oor ote ceck. The density of dusts covered Soe, eof the deck was not cedarls xoown, however, it may be supposed tha: socut USgrm-our se On the oer hand. the radicactivity of the dust yarlicles was regarded as avout 14 Curie wr at the tune of falling «3 hours after the detonation 4 \ssuming tnat ne irean diameter of dust particles was 0.1 mm, the ra. af of such particles m sea wateris about 30 m/hour. Then, it takes -, see 'o pass the water iayer of lem. Here, if we assume thar mi (UN % of the radioactive su’ stances in the dusts could dissolve into S@4 victim age second, ost tart fo vaojee 0s Mane ctals cwoul: save remove to water from tas'. oefure they teacte. Om te pon below tne sea surface. Thus, ely , e ae , " Water near the sed curface around there wou.d have been erat * coed ao che time fixe or sis cours after detunation. Needless to say, Ws was ‘ne actis oo oof Sea water o. t e area pout 130km apart from Bikini Acoii, therefore, tae actvity tear ane 1 the a ult would have been much more stronger Ontne other hand, it was. onhirnes oy the records of micro-barographs and tide gauges oDtained .n Japan o>» that " e \et'unations had teen carried out four or five times since Ist March ost Maren 7 +h March, 6th Apr.’, 25th Apr. and 5th Viav oat weu.d be no wonder toe wice ea urea far from Bikini Atoll had been contam.nated by fisesicn mater cis rs strongly as it Was actually observed 1 aboard . te >AUTKOTSUemaru of Dime 5. The property on the radioactive substarces in cea waiter The relation between the jross radioactis «| 4 uf the Loswon materagis und ve simp... exicvessec by the neat equation, the time afrer detonation may Aloe f where ¢ and @ are constants. krom the decay curve of the precipitates prepared aboard tne “Srurkx o'Su-maru”, i. has confined wittun the comparatively care wolimits of 1J~+1.6 the dare of detonation was ith May oo... norma. cases, @ is it was 137 tor the radivact:ive custs fel! on the deck of the radioactivity of the been found that @ 1s mean, 1.5 assuming about 1.2'5), whereas » Fuku-ryu-marnu ”. In sea water some of the radivactive elements contained in the original hs. sron materials might be preferentially precipitated owing to pH of sea water, vabout 8.2~%.2 Therefore, the chemical composition should be somewhat differ- ent from the orig.nal fission materials. stich might ve the cause of the change in the value cf a The radiochemical analysis of he ws or cnateriafs im sea wallet cate been furnished alsu by the present authors acv.cn will pe reported in near future. [nh Table 1 the fuil data of the gross act cots off sea water observed abeuarc the observat on vessel are given \y NeG o>