Gamma-radiation monitoring network at sea

A stationary monitoring network to observe the sea for radioactive contaminations, using a newly constructed NaI-detector system, is described. The monitoring efficiency for total-γ counting and γ-spectrometry as well as a method suppressing the registration of natural radioactivity are discussed. On the basis of three accident scenarios with releases of radioactivity into the sea it is demonstrated that under sea conditions the limit of detection of this “in situ” method is comparable to the regularly performed monitoring by radiochemical 137Cs analysis of seawater samples.