IVY, and a discussion of additional support required if Bikini were used. was supplemented ( echedule. nh hy a letter in April 1953 containing the initial Shot Changes followed in May (6) This (15) and in August came a revision in great This contained shot schedules, basic principles, timing and firing, construction, evacuation, description of test devices, radsafe and recovery operation, communications transportation, sample returns, fall-out pattern, support items » beaching conditions, climatology, and tide tables. Changes #1 anap”17)_ followed, altering the shot schedule. Altogether, these documents comprise a record of the test plan, including ways and means for, accomplishing the associated activities, and were a source of information additional to the actual Operations Orders. h, The weapons/devices situation during this period: ‘he types and/or models of veapons/devices to be tested became reasonably firm as did their respective yield predictions and the desired Qiagnostic studies tor each, It was during this period that the decision was made to extend the scope of CASTIE to include @ seventh detonation. The period was also characterized by various test assemblies ineluding eryogenics check-out when applicable. The experience gained by these assemblies led to conclusions governing shipping dates y uumber of personnel required, spare parts necessary, Randling g tools, etc. (14) Ltr J~16757, 7 Apr 53, from otaOTe to Distr, subj“General Concept of Operation CASTLE? J-Div Files. SSI-RD (15) Ltr J-18061, 19 May 53, SSI-RD (16) Ltr J-19161, 17 Aug 53, fram CTG 7.1 to Distr, Subj: “General Concept of Operation CASTLE". (Revision No. 1) J-Div ‘files, SSI-RD (17) Ltr J-19574, 24 Aug 53, and Ltr J-20173, 17 Sept 53, SSI-RD