A review of NPL Environmental radioactivity measurement intercomparison exercises: 1989–1995

Since 1989 the National Physical Laboratory (NPL) has conducted a series of five intercomparison exercises directed initially at the environmental radioactivity measurement community in the UK, but now open to overseas participants. The complexity of the intercomparison samples has increased with time. In general the results have been encouraging, but some problems have been highlighted, such as cascade summing and the sources of nuclear data. The intercomparisons are reviewed and the changes and improvement observed over time are discussed. The implications for quality assurance are also addressed.