English Abstract This report contains the results of dose rate
measurements carried out during 1990 at the site of the National Institute
of Public Health and Environmental Protection. The dose rates were
determined by means of thermoluminescence dosimeters on twelve locations.
One of these locations was meant for determination of the natural background
(reference) on the site. The dose rates averaged over a year, appeared not
to deviate significantly from the natural background levels in the
Netherlands. The small increase of the annual mean of the dose rate near
the building Sg, with regard to the reference level is due to irradiation
activities for calibration work and the replacement of the old Co-60-source
by a new one in July 1990 with a higher activity.