Speaker
Description
Authors (affiliation): 1. Wei-Han Chu (INER,Taiwan) 2. Wan-Tzu Hung (INER,Taiwan) 3. Ming-Chen Yuan (INER,Taiwan).
"Food safety" has been a major issue in Taiwan. Since the events of the Fukushima Daiichi nuclear disaster happening on March 11, 2011, the matter of man-made radioactive substances in food and food safety have soon caught Taiwanese attention. Undoubtedly, the correct detection for the content of radioactive substances in food has become the primary aim for ensuring food radiation safety. At present, there are eight food radiation testing laboratories in Taiwan that comply with ISO-17025 (the domestic equivalent document is CNS-17025) and are certified by the Taiwan Accreditation Foundation (TAF). According to the method of Announcement No. 1051900834 (MOHWO0015.00), the eight laboratories mainly perform the food detection for nuclear species like I-131 (iodine-131), Cs-134 (cesium-134) and Cs-137 (cesium-137).
The organizer (National Radiation Standard Laboratory) produced a set of reference samples that were traceable to the national measurement standards and passed them to the food radiation testing laboratories participating in this proficiency test. The test results were as follows:
1. The first stage of measurement
a. All samples with low specific activity could be detected in the first stage measurement.
b. For some small-amount specific activity samples, the measurement system could not determine the nuclear species in the first stage of measurement, but the existence of nuclear species could be judged by naked-eye observation.
2. The second stage of measurement
a. Among the total 228 measurement results, around 99% of them of had the deviation within 20%.
b. The average measurement uncertainty (k=1) is about 6.8%, and the average ratio to the reference value is 1.020±0.079 (k=1).
The competent authority used the test results to review the suitability of the presently announced methods, or as a reference for future revisions of the test methods. In the meantime, the test results are also shared with participating laboratories as a basis for their technical improvement to have high accuracy and consistency during the tests. Through the proficiency test carried out by this study, there should have been a comprehensive understanding of the applicability of the current testing methods. Besides, the technical capabilities of food radiation testing of the joined laboratories and the consistency of testing results will also play an important role in ensuring food safety for Taiwanese people.
