Building materials radon exhalation rate: ERRICCA intercomparison exercise results.

The Nuclear Engineering Section of the National Technical University of Athens undertook the organisation of a European building material radon exhalation rate intercomparison exercise in the framework of the European Research into Radon In Construction Concerted Action (ERRICCA). The intercomparison started in June 1998 and it was concluded in February 1999. Twenty participants from 13 countries took part. The exercise focused on the radon exhalation rate determination from a concrete slab, specially constructed to produce radon surface flux well below 10 mBqm(-2) s(-1). This paper describes the measurement results obtained using different instruments and methods in order to assess 'state-of-the-art' low-level radon exhalation measurements, being performed around Europe. Results are compared to each other and they provide an indication of the collective precision of such measurements for low exhalation rates. The agreement, with a few exceptions, is satisfactorily good.