Distribution of radionuclides in Dardanelle Reservoir sediments.

Natural and reactor-discharged gamma-ray emitting radionuclides were measured in Dardanelle Reservoir surface sediments taken near the Arkansas Nuclear One Power Plant site. Samples represented several water depths and particle sizes, at 33 locations, in a field survey conducted in early September 1980. Radionuclide contents of dry sediments ranged as follows: natural radioactivity (40K as well as uranium and thorium decay products) 661-1210 Bq/kg; and reactor discharged radioactivity (137Cs, 134Cs, 60Co,, 58Co, 54Mn), no detectable activity to 237 Bq/kg. In general, radionuclide contents were positively correlated with decreasing sediment particle size. The average external whole-body and skin doses from all measurable reactor-discharged radionuclides were calculated according to the mathematical formula for determining external dose from sediment given by the U.S. Nuclear Regulatory Commission (NRC). Inside the discharge embayment near the reactor discharge canal, the doses were 1.7 X 10(-3) mSv/yr to the whole body and 2.0 X 10(-3) mSv/yr to the skin. Outside this area, the doses were 0.15 X 10(-3) and 0.18 X 10(-3) mSv/yr to the whole body and skin, respectively.

Short communications.

The (3)He activation method for oxygen determination was applied to chalcogenide materials such as Ge(28)Sb(12)Se(60) and Ge(33)As(12)Se(55). Attention was focused on the optimization of the (3)He bombardment energy for non-destructive oxygen determination and the validity of the post-irradiation chemical etch used for removing surface oxygen contamination. The procedure developed was tested on a series of chalcogenide glasses. The detection limit for this non-destructive technique using ~6-MeV (3)He is estimated at ~1 ppm of oxygen.

Fallout from the Chinese nuclear explosion of 17 June 1967.

Low-level activities of iodine-131, barium-140, and strontium-89 were found in a series of rain samples collected at Fayetteville, Arkansas, during the period from late June through August 1967. The ratios of these short-lived isotopes to strontium-90 were determined as accurately as possible. The data indicate that the debris from the Chinese nuclear explosion was injected primarily into the stratosphere.