FöRFATTARE
Nygren, Ulrika

DATUM
2001-11-23

INSTITUTION
Kemi och metallurgi / Oorganisk kemi

SAMMANFATTNING
Radioactive nuclides present a potential health hazard due to the ionising radiation emitted during their decay. The release of large amounts of radioactive nuclides is of concern both for man and the environment. In cases of an accidental (or intentional) release, it is important with early warning systems and rapid methods to determine the extent and composition of the radioactive contamination. Many of the radionuclides released from a nuclear power plant accident or the detonation of a nuclear weapon can be determined by the use of gamma spectrometry. There are, however, some nuclides that are considered to be among the more hazardous that cannot be well determined by this technique, e.g. 90Sr and the actinides. The determination of these nuclides is usually very time consuming due to the need for their chemical separation prior to counting.

Two methods developed for the determination of 90Sr and actinides in preparedness situations are described in this thesis. The determination of 90Sr is based on a rapid decomposition of inorganic sample matrixes by lithium-borate fusion and preconcentration of Sr by coprecipitation with calcium oxalate with HF acting as a hold-back carrier for silica. The separation of Sr is then performed by extraction chromatography and measurement by gas-flow proportional counting.

The method for actinide-determination is based on collection of the elements from various kinds of sample-materials by the use of two different actinide selective resins. The sample is, in this way, preconcentrated and partially purified prior to the analysis with low-energy gamma spectrometry. Sample preparation by this method only requires 1½ - 2½ hours and the sensitivity is sufficient for many of the nuclides of interest. For those nuclides that require a more sensitive analytical finish, the actinides can be removed from the resin and processed further for, e.g., alpha spectrometric determinations.

ISSN 1402-1757 / ISRN LTU-LIC--01/69--SE / NR 2001:69