scholarly journals Measurement of anthropogenic radionuclides in post-Fukushima Pacific seawater samples

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 545-550 ◽  
Author(s):  
Guillaume Lutter ◽  
Faidra Tzika ◽  
Mikael Hult ◽  
Michio Aoyama ◽  
Yasunori Hamajima ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Power Plant ◽  
North Pacific ◽  
Nuclear Power ◽  
Gamma Ray ◽  
Gamma Ray Spectrometry ◽  
Anthropogenic Radionuclides ◽  
Vast Number ◽  
Hpge Detectors ◽  
Seawater Samples

Abstract Following the accident at the Daiichi Fukushima nuclear power plant in 2011, a vast number of Pacific seawater samples from many locations far from Fukushima have been collected by Japanese investigators. Due to dilution, the activities of radionuclides from North Pacific seawater samples are very low, which calls for extraordinary measures when being measured. This study focuses on the metrological aspects of the gamma-ray spectrometry measurements performed on such samples in two underground laboratories; at HADES (by JRC-IRMM in Belgium), and at Ogoya (by Kanazawa University in Japan). Due to many samples and long measurement times, all available HPGe detectors needed to be employed. In addition to single coaxial detectors, this involved multidetector systems and well detectors. Optimization of detection limits for different radionuclides and detectors was performed using Monte Carlo simulations.

Evaluation of Monte Carlo-based calibrations of HPGe detectors for in situ gamma-ray spectrometry

2009 ◽  
Vol 100 (11) ◽  
pp. 935-940 ◽  
Author(s):  
Jonas Boson ◽  
Agneta H. Plamboeck ◽  
Henrik Ramebäck ◽  
Göran Ågren ◽  
Lennart Johansson
Keyword(s):  
Monte Carlo ◽  
Gamma Ray ◽  
Gamma Ray Spectrometry ◽  
Hpge Detectors

Design, calibration, and application of an airborne gamma spectrometer system in Switzerland

Geophysics ◽  
1997 ◽  
Vol 62 (5) ◽  
pp. 1369-1378 ◽  
Author(s):  
Georg F. Schwarz ◽  
Ladislaus Rybach ◽  
Emile E. Klingelé
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Gamma Ray ◽  
Point Sources ◽  
Swiss Alps ◽  
Artificial Radioactivity ◽  
Radiation Level ◽  
Satellite Navigation System ◽  
Emergency Situations

Airborne radiometric surveys are finding increasingly wider applications in environmental mapping and monitoring. They are the most efficient tool to delimit surface contamination and to locate lost radioactive sources. To secure radiometric capability in survey and emergency situations, a new sensitive airborne system has been built that includes an airborne spectrometer with 256 channels and a sodium iodide detector with a total volume of 16.8 liters. A rack mounted PC with memory cards is used for data acquisition, with a GPS satellite navigation system for positioning. The system was calibrated with point sources using a mathematical correction to take into account the effects of gamma‐ray scattering in the ground and in the atmosphere. The calibration was complemented by high precision ground gamma spectrometry and laboratory measurements on rock samples. In Switzerland, two major research programs make use of the capabilities of airborne radiometric measurements. The first one concerns nuclear power plant monitoring. The five Swiss nuclear installations (four power plants and one research facility) and the surrounding regions of each site are surveyed annually. The project goal is to monitor the dose‐rate distribution and to provide a documented baseline database. The measurements show that all sites (with the exception of the Gösgen power plant) can be identified clearly on the maps. No artificial radioactivity that could not be explained by the Chernobyl release or earlier nuclear weapons tests was detected outside of the fenced sites of the nuclear installations. The second program aims at a better evaluation of the natural radiation level in Switzerland. The survey focused on the crystalline rocks of the Central Massifs of the Swiss Alps because of their relatively high natural radioactivity and lithological variability.

scholarly journals Ecosystem model-based approach for modeling the dynamics of <sup>137</sup>Cs transfer to marine plankton populations: application to the western North Pacific Ocean after the Fukushima nuclear power plant accident

2016 ◽  
Vol 13 (2) ◽  
pp. 499-516 ◽  
Author(s):  
M. Belharet ◽  
C. Estournel ◽  
S. Charmasson
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Pacific Ocean ◽  
Dose Rate ◽  
North Pacific ◽  
Nuclear Power ◽  
Western North Pacific ◽  
North Pacific Ocean ◽  
Ecosystem Model ◽  
Western North Pacific Ocean

Abstract. Huge amounts of radionuclides, especially 137Cs, were released into the western North Pacific Ocean after the Fukushima nuclear power plant (FNPP) accident that occurred on 11 March 2011, resulting in contamination of the marine biota. In this study we developed a radioecological model to estimate 137Cs concentrations in phytoplankton and zooplankton populations representing the lower levels of the pelagic trophic chain. We coupled this model to a lower trophic level ecosystem model and an ocean circulation model to take into account the site-specific environmental conditions in the area. The different radioecological parameters of the model were estimated by calibration, and a sensitivity analysis to parameter uncertainties was carried out, showing a high sensitivity of the model results, especially to the 137Cs concentration in seawater, to the rates of accumulation from water and to the radionuclide assimilation efficiency for zooplankton. The results of the 137Cs concentrations in planktonic populations simulated in this study were then validated through comparison with the data available in the region after the accident. The model results have shown that the maximum concentrations in plankton after the accident were about 2 to 4 orders of magnitude higher than those observed before the accident, depending on the distance from FNPP. Finally, the maximum 137Cs absorbed dose rate for phyto- and zooplankton populations was estimated to be about 5  ×  10−2 µGy h−1, and was, therefore, lower than the predicted no-effect dose rate (PNEDR) value of 10 µGy h−1 defined in the ERICA assessment approach.

scholarly journals Experimental and Simulated Spectral Gamma-Ray Response of a NaI(Tl) Scintillation Detector used in Airborne Gamma-Ray Spectrometry

2021 ◽  
Author(s):  
David Breitenmoser
Keyword(s):  
Monte Carlo ◽  
Gamma Ray ◽  
Radiation Transport ◽  
Natural Uranium ◽  
Detector Response ◽  
Gamma Ray Spectrometry ◽  
Response Analysis ◽  
Maximum Relative Error ◽  
Potassium Sources ◽  
Significant Difference

&lt;p&gt;The objective of this work is to simulate the spectral gamma-ray response of NaI(Tl) scintillation detectors for airborne gamma-ray spectrometry (AGRS) using Monte Carlo radiation transport codes. The study is based on a commercial airborne gamma-ray spectrometry detector system with four individual NaI(Tl) scintillation crystals and a total volume of 16.8 l. Monte Carlo source-detector simulations were performed in an event-by-event mode with the commercial multi-purpose transport codes MCNP6.2 and FLUKA. Validation measurements were conducted using &lt;sup&gt;241&lt;/sup&gt;Am, &lt;sup&gt;133&lt;/sup&gt;Ba, &lt;sup&gt;60&lt;/sup&gt;Co, &lt;sup&gt;137&lt;/sup&gt;Cs and &lt;sup&gt;152&lt;/sup&gt;Eu radiation sources with known activities and source-detector geometries. Energy resolution functions were derived from these measurements combined with additional measurements of natural Uranium, Thorium and Potassium sources. The simulation results are in good agreement with the experimental data with a maximum relative error in the full-energy peak counts of 10%. In addition, no significant difference between the two Monte Carlo radiation transport codes was found with respect to a 95% confidence level. The validated detector model presented herein can be adopted for angular detector response analysis and calibration computations relating radionuclide activity concentrations with spectral detector counts.&lt;/p&gt;

Nonlinear Probabilistic Analysis of the Failure Pressure of NPP Shielding Plate

2016 ◽  
Vol 837 ◽  
pp. 214-221
Author(s):  
Juraj Kralik ◽  
Juraj Kralik Jr. ◽  
Maros Klabnik ◽  
Alzbeta Grmanova
Keyword(s):  
Monte Carlo ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Probabilistic Analysis ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Fragility Curve ◽  
Failure Pressure ◽  
Surface Method ◽  
Central Composite

This paper describes the nonlinear probabilistic analysis of the failure pressure of the shielding plate of the reactor box of the nuclear power plant under a high internal overpressure and temperature. The scenario of the hard accident in Nuclear power plant (NPP) and the methodology of the calculation of the fragility curve of the failure overpressure using the probabilistic safety assessment PSA 2 level is presented. The fragility curve of the failure pressure was determined using 45 probabilistic simulations using the response surface method (RSM) with the Central Composite Design (CCD) for 106 Monte Carlo simulations for each model and 5 level of the overpressure.

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