Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Sasaki, Miyuki; Sanada, Yukihisa; Lee, E.*; Joung, S.*; Ji, Y.-Y.*
no journal, ,
Since the Fukushima Daiichi Nuclear Power Plant accident, some types of radiation monitoring have been conducted in Japan. Walking surveys and unmanned helicopter surveys have been conducted around the FDNPP to the ambient dose equivalent rates (air dose rate). The airborne radiation survey (ARS) by unmanned helicopter has the advantage of measuring large areas including forests. However, ARS has lower measurement resolution than walking surveys. Sasaki et al. constructed an artificial neural network (ANN) to convert ARS data into air dose rates at 1 m above ground level using data accumulated after the accident (Ref). It has been reported that the conversion using ANNs can convert to values closer to those measured on the ground than the conventional method. Showing that the ANN constructed from the Fukushima experience can be applied to detectors other than the radiation detector used to construct the ANN will greatly contribute to the future development of ARS. In this study, we investigated how to apply radiation measurement data acquired with a detector different from the radiation detector used to acquire the training data to an ANN that has already been constructed.
Sato, Tatsuhiko
no journal, ,
The Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo radiation transport simulation code that can analyze the motion of radiations in any material using the nuclear/atomic reaction models and libraries. It has been used in more than 60 countries for various applications such as radiation shielding design, medical physics, and cosmic-ray researches. In this presentation, the general features of the PHITS code together with its applications to cosmic-ray dosimetry including the developments of PARMA (PHITS-based Analytical Radiation Model in the Atmosphere) and WASAVIES (WArning System for AVIation Exposure to Solar energetic particle) will be introduced.
Iguchi, Tetsuo; Maeda, Shigetaka
no journal, ,
We developed the new unfolding code, the Maximum Entropy and Maximum Likelihood Unfolding Code (MEALU), based on the maximum likelihood method combined with the maximum entropy method, which can determine a neutron spectrum without requiring an initial guess spectrum. Normal or Poisson distributions can be used for statistical distributions. MEALU can treat full covariance data for a measured detector response and response function. In this study, we applied MEALU to neutron spectrum measurements using a multi-cylindrical Bonner counter, which is a typical underdetermined problem in radiation measurements and has more smooth response than multiple activation foils. Neutron spectra were obtained from the measurement results of the six Bonner counters without using the initial estimated spectra. The obtained neutron spectra reproduced the measured results well.
Joung, S.*; Ji, Y.-Y.*; Choi, Y.*; Lee, E.*; Ji, W.*; Sasaki, Miyuki; Ochi, Kotaro; Sanada, Yukihisa
no journal, ,
KAERI (Korea Atomic Energy Research Institute) has developed the MARK A1 aerial survey system for unmanned aerial vehicles for use in contaminated areas. The MARK A1 system consists of a CZT detector, signal processing unit, and positioning and interface units to a PC on the ground. To validate the effectiveness of the detectors, field tests were conducted in high dose rate environments near the Fukushima Daiichi Nuclear Power Station. The JAEA and KAERI detectors were each mounted on an unmanned helicopter to make measurements at different altitudes. For both systems, the air dose rates obtained from the airborne survey gave results with a similar trend to the air dose rates obtained from the walking survey. Therefore, it is expected that MARK A1 can be used to quickly scan large and highly contaminated areas that are difficult for humans to access in the event of a nuclear accident.