[en] This report contains a presentation and evaluation of an emergency preparedness exercise (LOTTA) that was carried out at FOA NBC Defense in May 1998. The exercise scenario was based on a nuclear weapons explosion in Norway and the paper describes the development of the scenario including weather prognosis for the simulation of dose rate-, laboratory- and field measurements made during the exercise. An evaluation of the different functions trained is also given. This is the main report in a series of reports concerning exercise LOTTA