—-3— oceanogravhic observation in the Christmas and Johnston Honolulu, and conducted radiological surveys of sea water, plankton and fish caught by longline, together with routine On the 13th of August, the R.V. Shoyo-Maru departed ing the cruise, was received. mercial Fisheries, and the Laboratory of Radiation Biology, University of Washington to discuss the operational aspects Also, information on radiation contaminaof the cruise. tion 4n the Central Pacific waters for safety purposes dur- the Division of Operation Safety, U.S. Atomic Energy Com mission; the U.S. Public Health Service; the Bureau of Com- the scientists aboard attended a meeting with the staffs of During the period 10-12th of August, while at Honolulu, The ship sailed eastward on a straight course collecting water and plankton samples until its arrival at Honolulu on the 9th of August. Shown in Fig. 2. The ship track is 1962, the R.V. Shoyo-Maru depart~ ed from Tokyo for the Central Pacific. On the 27th of July Course and Itinerar Spectrometer with a Scintillation Probe. Other equipment and apparatuses were arranged as shown in Fig. 1. other apparatuses. The Counting Laboratory, located in the stern, contained a Geiger-Muller counter fitted with an automatic sample changer and a 128~Channel Scintillation The Radiochemical Laboratory, located in the forcastle, was equipped with a chemical hood, two muffle furnaces and residential quarters to the upper deck. sonnel was built in the area of the doorway leading from the tilators were installed. Furthermore, a special compart~ ment for radiation detection and decontamination of per- the air-conditioning system and asbestine filters for ven- To keep the interior of the ship safe from radiation contamination, absolute filters for the inherent openings in Equipment for Operation Cruise 7 These values were dane. berGross f-radioactivity in the Gir] ranged from 0,1-5.9 UNO/gg? ‘andjthat in fPainyater) from 0.2-7.0 uwac/mg. 2 ‘Radioactivity RESULTANT Tokai Regional Ficheries Research Laboratory, National Institute of Radiological Sciences. Japan Analytical Chemistry Research Institute. Agency. Meteorological Research Institute. Hydrographic Division, Maritime Safety Board Meteorological Research Institute. Organizations orth Equatorial Current and the Equatorial Countercurrent Gross g-radioactivity in sea water from the South Equatorial m Current was found to be less than 14*9y., while those from the . ecognized tobeofalowlevel. Gomposition of radio nuclides Min rain, water are developing by Meterological Research Institute. ¥ , ; ~” Plankton ‘Fish __Sea water Rain water Samples Samples collected by the 5.V. Shoyo-Maru were transfered to following organizations for radiochemical analysis. s\in' the air snd rainwater were made each day during the entire _ Measurements of the radiation dose rate and radioactivity dt, \'Yéached ‘Tokyo on the 17th of September. ~ Island areas, then, returned to Honolulu on the 3lst of August. On the 4th of September, after refucling in Honolulu, the ship * departed taking a westward course to Tokyo. Radiological surveys (of ‘surface water and plankton were conducted until the ship