Radiological study of a wastewater treatment plant associated with radioiodine therapy at a hospital in West Java, Indonesia.

Nuclear medicine (NM) services in Indonesia have rapidly developed due to the increasing number of patients, and this growth has been supported by standardized regulations in the field, including the management of solid waste generated. However, multiple reports indicate that licensing control does not regulate liquid waste disposal from patient excretions to protect personnel and the community from radiopharmaceutical exposure. One of the radiopharmaceuticals commonly used in NM and having the longest half-life among the radiopharmaceuticals used in NM is iodine 131(I-131). Thus, this study used a high-purity germanium detector to measure iodine-131 (I-131) activity in liquid waste from decay tanks, temporary collection channels, the hospital's wastewater treatment plant (WWTP) outlet, and six points around the NM service and liquid waste treatment unit. Concentration measurements in three decay tanks were carried out sequentially every 12 h for 3 d, corresponding to the therapy period. The results showed that the I-131 activity levels in the decay tanks and temporary collection channels, before being mixed with liquid waste from other units, were 95.9 × 106± 4.4 × 106Bq m-3.At the point where the liquid waste from other units was mixed, the activity level decreased significantly to 472 680 ± 22 160 Bq m-3, which was below the clearance level of 107Bq m-3. However, the recorded concentration exceeded the standard for environmental radioactivity at the hospital's WWTP outlet, namely 37 670 ± 2040 Bq m-3. The measurement results for I-131 in the air in the open space for two nuclear buildings was above the standard at 1.3 ± 0.27 Bq m-3. According to the RESRAD simulation, based on the initial dose taken from the liquid waste treatment outlet point, the accumulation of doses and the risk of cancer among workers and the community decreased within 3 months after the maximum exposure.

Trend of strengthening clearance regulation in Japan and concerns about its worldwide effects on regulations for natural and artificial radionuclides.

The Nuclear Regulation Authority (NRA) of Japan invited comments from the public on a revised guide on measurement and evaluation for clearance in 2019, which included a strict decision on how to treat uncertainties in the measurement and the nuclide vector. To resolve the issue on the uncertainty in clearance, a probabilistic approach had been established previously in the Atomic Energy Society of Japan Standard and incorporated into International Atomic Energy Agency (IAEA) Safety Report No. 67. NRA's new decision on the uncertainty in clearance was up to 10 times stricter than the probabilistic approach. This issue has been discussed at an international level in the framework of the ongoing revision of IAEA Safety Guide RS-G-1.7. This discussion on the uncertainty in clearance has raised serious concerns about its effects on other radiological protection regulations worldwide. This is because if we need strict treatment for the uncertainty in clearance, the same or even stricter treatment for conformity assessment may have to be applied to other radiological protection criteria for doses exceeding 10 µSv year-1. Radiological protection experts including regulators, professionals, and operators should be aware of the essential meaning of the radiological protection criteria by considering the background scientific basis on which they were established.

New high-throughput measurement systems for radioactive wastes segregation and free release.

This paper addresses the measurement facilities for pre-selection of waste materials prior to measurement for repository acceptance or possible free release (segregation measurement system); and free release (free release measurement system), based on a single standardized concept characterized by unique, patented lead-free shielding. The key objective is to improve the throughput, accuracy, reliability, modularity and mobility of segregation and free-release measurement. This will result in a more reliable decision-making with regard to the safe release and disposal of radioactive wastes into the environment and, resulting in positive economic outcomes. The research was carried out within "Metrology for Decommissioning Nuclear Facilities" (MetroDecom) project.

Proficiency testing criteria for clearance level in solid waste gamma measurement in Taiwan.

To guarantee the measurement quality for clearance level in solid waste material, the Institute of Nuclear Energy Research (INER) established the criteria for proficiency testing of clearance level measurement. INER and the Taiwan Accreditation Foundation (TAF) organized the Technique Committee Meeting twice to discuss these criteria in 2011. The participating laboratories must completely conform to the ISO/IEC 17025, and they also must meet the requirements of the criteria. According to the criteria, the participating laboratories analyzed the minimum detectable amount (MDA) and that should be less than 20% of the clearance level (AMDA) given in the Atomic Energy Council's (AEC) "Regulations on Clearance Level for Radioactive Waste Management". The testing results should conform to the deviation and traceability requirements.