RRFM 2009 Transactions - European Nuclear Society

THE JAMAICAN SLOWPOKE-2 RESEARCH REACTOR:
NEUTRON ACTIVATION ANALYSIS IN ENVIRONMENTAL
AND HEALTH STUDIES
Charles Grant, Gerald Lalor and John Preston
International Centre for Environmental and Nuclear Sciences
University of the West Indies
Mona Road, Kingston 7 – Jamaica
ABSTRACT
In its 24 years of existence the reactor has been utilized mainly for Neutron
Activation Analysis (NAA) and has played an important role in the development of
research programs in the areas of archaeology, biology, chemistry, forensics,
geochemistry, and mining as well as for the production of short lived radioisotopes
for experimental work in the physics department. However, over the last fifth teen
years our main thrust has been environmental geochemistry, agriculture and health
related studies, with interesting results that have implications for land use, farming
practices, diabetic control and dietary intakes during pregnancy.
1. Introduction
The SLOWPOKE-2 research reactor at the International Centre for Environmental and
Nuclear Sciences (ICENS) is a light water moderated open swimming pool type reactor with a
beryllium reflector. The first criticality was achieved in March 1984. The reactor in Jamaica is one of
only seven ever built and is the only one outside of Canada. Presently there are still five operating,
three of which utilise HEU [1] fuel and two LEU [2]. Although Jamaica presently operates with a HEU
core, we are committed to convert to LEU and fully support the Global Threat Reduction Initiative
(GTRI) and Reduced Enrichment for Research and Test Reactors (RERTR) programs.
The reactor normally operates at a power of 20 kW for approximately 5 hours per day, 5 days
per week. It has now operated for a total 9.78 x 10 4 -kilowatt hours out of a calculated lifetime of
3.395 x 10 5 kWh or 28.8% of total lifetime. Although only rated at 20 kW, SLOWPOKE-2 has the
highest flux to power ratio of research reactors in this class. The remarkable flux stability of the
SLOWPOKE-2 has provided ICENS with a robust, reliable and economical analytical platform.
Although NAA is now a mature technique, improvements in gamma spectroscopy detectors
and fast counting systems have lead to incremental reductions in detection limits allowing NAA to
remain competitive with newer techniques such as ICPMS. The ability to quantify elements in almost
any matrix without dissolution and the dynamic analytical quantification range make NAA an ideal
tool for environmental studies where sample types vary from geological samples with percentage level
concentrations to biological samples with elemental concentration levels in the parts per billion range.
This presentation reports on the performance of the SLOWPOKE-2 reactor and its utilization
for the analysis of a wide variety of environmental samples using NAA. The detection limits for the
major sample types are presented along with data obtained, for soils, plants, animal and human tissues
and there possible implications.
2. Methodology
271 of 455
1