in monitoring techniques, working conditions were deplorable by present-day standards. q $ Fortunately, T F Criginal count oT T qT T qT After decontamination g!or after initial bomb processing was completed in Oo August 1946, all work with plutonium was sharply | curtailed until the new and greatly improved facilities at DP Site in Los Alamos were opened in 4 L i 1 A 7 8 S$ 4 WOW 6 T T T ‘ T TO 2 Af 8 24 2 to f LI June t July 4 Percent of Rooms Whose ‘Counts’ Are Over 5.000 = J Original count September 1946. 40/- To illustrate the degree of contamination of laboratories in D Building in 1944 and 1945, we will Table I shows Oo | ‘ per minute correspond to 0.007 ug or 0.0004 pCi of Fig. 2,500,000 count per minute (or 35 Ug) swipe in D-117 4. Figure 4 shows 7 B June 9 24 30 4 6 2 4 18 July 4 2 4 Chart showing the percent of laboratories in D Building in June and July 1945 with “hot" spots requiring decontamination. The lower line indicates the counts after decontamination. Note that about 50 percent of the laboratories had contamination in excess of 500 counts per minute on two occasions. RARKK During the war years, when piutonium was the primary concern of the radiochemists, the unit of measure of plutonium was usually considered to be its weight (i.e., micrograms, grams, etc.). 7 Percent of Rooms Whose “Counts” Are Between 500 and 5000 plutonium isotope mixture of that time; note the )}. 7 10 oratories in D Building in March 1944 [500 counts (used by the Recovery Group J a 2, the maximum and minimum "swipe”™ counts in all lab- RAEKKK After Decontamination 2 present a few almost random experiences taken from various reports issued at the time. 4 = 30 o In the 1950's, presumably because of the influence of the health physicists (and because chemists became more involved with physics), radioactivity (i.e., micro‘curies, etc.) became the unit of measure. Both units are given throughout this paper. TABLE I MAXIMUM AND MINIMUM SWIPE COUNTS IN D BUILDING (MARCH 1944) Room No. First Maximum Minimum Last 101 16 274 0 18 102 158 3,319 32 642 103 110 739 24 122 104 399 14,560 12 150 108 338 4,652 60 826 109 177 4,078 50 3,547 110 321 15,176 59 59 112 807 17,450 27 51 113 308 561 17 57 114 10 172 4 31 Room No. First 115 33 116 9 117 8 118 244 119 10 0 21 9 37 0 1,198 120 3 816 121 0 81 0 42 122 12 128 0 24 123 90 130 12 64 124 7 176 5 46 126 73 17,832 127 44 363 133 41 610 3 13 134 58 68 Q 25 136 6 3,712 oO 91 Maximum Minimum Last 70 §8 2,500,000 6,000 1,387 128 52 94 129 83 83 1 2,368 10 48 16 19 2 0 QO 506 28 22 46 6 132 6 5,796 1 85 Room No. First Maximum Minimum Last 137 93 2,928 0 833 138 7 448 6 33 139 23 23 7 12 140 81 81 12 42 141 0 15 O 2 143 8 15 8 8 144 0 0 0 30 145 0 114 0 126 146 338 338 5 16 Room No. 148 151 152 201 202 30 30 0 204 0 0 0 0 205 21 21 21 21 207 45 45 45 45 209 73 73 73 73 Room No. First Maximum Minimum Last First Maximum Minimum Last Reem No. 125 40 4,592 30 20 20 79 18 36 210 211 First 19 22 Maximum 19 22 Minimum 19 Last 19 104 0 42 23 23 23 23 9 9 9 9 22 22 wes