Metrology for the mobile detection of ionising radiation following a nuclear or radiological incident ‒ The EMPIR project “Preparedness”

In cases of nuclear or other radiologically relevant incidents or accidents (“radiological event”), including terrorist attacks, appropriate protection of the public against ionising radiation and radioactive contamination is of major importance. In such scenarios, radiation protection authorities and other decision-makers quickly need reliable information based on sound radiological data in order to determine and optimize countermeasures. The nuclear accidents in Chernobyl (1986) and Fukushima (2011) are major examples where radiation protection measures were crucial for preserving a tremendous number of human lives. However, certain smaller events have also caused severe problems, e.g., the Tokaimura nuclear criticality accident (1999). According to the IAEA Safety Standard No. GSR Part 7, “Preparedness and Response for a Nuclear or Radiological Emergency” (1), safety and security measures have the shared aim of protecting human life and health as well as protecting the environment. This document also emphasises the importance of adequate protective measures following nuclear and radiological emergencies. Reliable radiological data, available at the earliest possible stage, are a prerequisite for effectively protecting people from such unexpected but potentially highly dangerous events. Therefore, the European joint research project 16ENV04 named “Preparedness”, funded by the European Metrology Programme for Innovation and Research (EMPIR), is meant to develop reliable instrumentation and methods needed in the field of radiation protection in the aftermath of a nuclear or radiological emergency. The goal is to quickly gather quantitative data on the activity concentrations of contaminated areas and dose rate levels by aerial measurements, and analyse these air contaminations by flexible and transportable air sampling systems. For large-area ground contaminations, surveillance by unmanned airborne monitoring systems (UAMSs), specifically unmanned aerial vehicles (UAVs) equipped with spectrometric detectors, is the best solution to protect first responders and other task forces against contaminations and hazards due to ionising radiation. However, advanced calibration procedures based on reference materials and standard radionuclide sources must be elaborated for these systems and verified by Monte Carlo simulations. For airborne radioactivity monitoring, transportable air sampling field stations equipped with high-resolution spectrometric detectors and appropriate shielding is needed to allow the measurement of radioactivity concentration levels in the air of affected areas. After the release of a radioactive plume to the atmosphere, the levels of the ambient dose equivalent rate and activity concentrations in air provide essential information about the progression of the radioactive cloud. This information is important for decision-makers to be able to take timely and adequate countermeasures to protect the members of the public against the dangers of ionising radiation. After a major release of radionuclides, short-term decontamination may not always be possible. Hence, concepts for long-term measurements have to be developed. Metrologically sound data is needed in this field as well, because decisions on e.g. decontamination measures or release of restricted areas are of vital importance. Passive dosimeters must therefore be studied with regard to their applicability for this purpose. Furthermore, the “Preparedness” project addresses the question whether non‐governmental networks could support official dose rate data or undermine them because of insufficient quality.