2 CASES OF RECOVERY OF KILOCURIE SOURCES FALLEN FROM TELEGAMMA UNITS

Recently, two incidents involving the fall of kilocurie sources from t elegamma units during repairs occurred in India. In one case it was a Co-60 source of activity 222 TBq (6,000 Ci) and in the other case, it was a Cs-137 source of activity 75.85 TBq (2,050 Ci). The line of acti on planned for the recovery of the sources was to cover the sources wi th large quantities of lead shots sent through a sloping pipe, thereby reducing the exposure rate. Once this was arranged, the workers could go inside for further retrieval action. An aluminium container was de signed and positioned over the source drawer and lead shots were poure d into this container. The retrieval operation was executed as planned but with slight modifications as necessitated at the sites. The colle ctive effective dose for the recovery of the first source was approxim ately 0.07 person-sievert (7 person-rem) and for the second one was <0 .01 person-sievert (1 person-rem).