⁸⁵Kr Extraction from Water Samples

Abstract

A system for extracting krypton from a sample of natural water preextracted under field conditions is described. A carbon trap at –76°C is used to precipitate inert gases. The β radiation of ⁸⁵Kr is detected using a 3.5-liter multiwire proportional counter, placed on the ground and in a gallery at a depth of 500 m water equivalent in a low-background counter. The background of the counter enclosed in shielding with a built-in anticoincidence ring in the ⁸⁵Kr β-particle energy range is 0.8 counts/min on the surface and 2 counts/h in the underground laboratory.

Various schemes for degassing and removing krypton from water samples are examined – heating, bubbling, and vacuum degassing. The extraction coefficients for dissolved gases are as follows: 88 ± 2% for extraction by heating water, 95 ± 3% for bubbling, and 70 ± 10% for vacuum degassing.

Preliminary measurements show that the ⁸⁵Kr concentration in different natural waters in Krasnodarsk krai is 130–1080 decays/min·mmole.