The observation of fallout during the period of 1971–1975 is presented. Relatively high activity from nuclear tests at Lop Nor of mainland China was detected twice in this period. The gamma-ray spectrum of the hot fallout after the 11th nuclear test is given. The high activity peaks in the figures included are indicated with corresponding dates and sequence number of the tests for easy identification and comparison. The calibration of thermoluminescent dosimeters for the low exposure rates is presented. The gross beta activities are much more likely to build up in milk and surface water samples. Their intensity and duration are more significant than other foodstuff samples, and the timing of their appearance is more predictable.
©1977Health Physics Society