Operation and performance of a National Monitoring Network for Radioactivity in Food

- Monitoring network of easy to use gamma detectors for radioactivity in food.
- Measured activities all within tolerance limits in proficiency tests.
- Recalibration resulted in a reduction of 40% in the variation of the precision.

In the Netherlands, the EU-mandated nationwide monitoring programme and emergency response plan for radioactivity in food is implemented by RIKILT (the Dutch institute for food safety) by means of the National Monitoring Network for Radioactivity in Food (LMRV). The LMRV consists of 48 individual gamma spectrometers (Food Monitoring System, or FMS) that require little maintenance, are hosted at food processing companies and institutes throughout the Netherlands, and are operated by local personnel. From 2010 to 2013, approximately 900 samples of milk and 500 samples of other food categories were analysed on the FMSs annually, and another 1400 in the specialized radionuclide laboratories operated by RIKILT. The anthropogenic radionuclide cesium-137 (137Cs) was detected in 93 out of 11,143 samples (0.8%), mostly in wild mushrooms, game and honey. Two samples of wild boar exceeded the limit of 600 Bq/kg. In case of a nuclear accident the FMSs are used to validate the radioactive deposition calculated by dispersion models by measuring radionuclides in grass samples. No deposition of artificial radionuclides was measured in the Netherlands after the Fukushima nuclear incident. The precision of the FMSs is within the pre-set tolerance limits of 80-120% for 137Cs, cobalt-60 (60Co) and iodine-131 (131I). For potassium-40 (40K) a systematic error of +10% was observed. The recalibration of the FMSs in 2012 resulted in a reduction of almost 40% in the variation of the precision for 131I (compared to 2010 and 2011). This article describes the network and the individual FMSs, the routine measurements of food and special measurements in case of radioactive contamination, and the performance of the network.