Wolfango Plastino

Dispersion of Fukushima radionuclides in the global atmosphere and the ocean

Large quantities of radionuclides were released in March-April 2011 during the accident of the Fukushima Dai-ichi Nuclear Power Plant to the atmosphere and the ocean. Atmospheric and marine modeling has been carried out to predict the dispersion of radionuclides worldwide, to compare the predicted and measured radionuclide concentrations, and to assess the impact of the accident on the environment. Atmospheric Lagrangian dispersion modeling was used to simulate the dispersion of (137)Cs over America and Europe. Global ocean circulation model was applied to predict the dispersion of (137)Cs in the Pacific Ocean. The measured and simulated (137)Cs concentrations in atmospheric aerosols and in seawater are compared with global fallout and the Chernobyl accident, which represent the main sources of the pre-Fukushima radionuclide background in the environment. The radionuclide concentrations in the atmosphere have been negligible when compared with the Chernobyl levels. The maximum (137)Cs concentration in surface waters of the open Pacific Ocean will be around 20 Bq/m(3). The plume will reach the US coast 4-5 y after the accident, however, the levels will be below 3 Bq/m(3). All the North Pacific Ocean will be labeled with Fukushima (137)Cs 10 y after the accident with concentration bellow 1 Bq/m(3).

Cosmic background reduction in the radiocarbon measurements by liquid scintillation spectrometry at the underground laboratory of Gran Sasso

Radiocarbon measurements by two 1220 Quantulus ultra low background liquid scintillation spectrometers were performed at the underground laboratory of Gran Sasso and the Radiocarbon Laboratory of E.N.E.A.-Bologna to study the efficiency and background variations related to measurement sites. The same configuration setup, i.e. the same center of gravity of the 14 C spectrum (SQP(I) = 410 ± 1) was obtained in both instruments. Many different background and modern standards with pure analytical benzene were used and spectra for 40 one-hour periods were obtained. The data indicates a background reduction of approximately 65% between the surface and underground laboratories, with no differences in the efficiency. Recording similar efficiencies in both spectrometers is probably due to fairly identical photomultiplier characteristics. The cosmic noise reduction observed at the laboratory of Gran Sasso makes it possible to perform high precision 14 C measurements and to extend for these idealized samples the present maximum dating limit from 58,000 BP to 62,000 BP (5 mL, 3 days counting).

Radon groundwater monitoring at underground laboratories of Gran Sasso (Italy)

An automatic multiparametric equipment (groundwater temperature, electrical conductivity, pH, 222Rn) has been planned and realized to study the correlations between the variations of radon with the strain processes of the rock and transport properties related to the groundwater geochemistry. The monitoring activity at underground laboratories of Gran Sasso with a groundwater sampling period of twelve hours has been started from May 1996. From geochemical data recorded during the first year a high dynamic behaviour of shallow aquifer has been emphasized due to high permeability of the cretaceous limestones that form part of the Gran Sasso massif. Also, the residual time series analysis of the geochemical parameters has emphasized pre-co seismic anomalies in electrical conductivity and post-seismic in radon content in groundwater related to local seismicity.

Estimation of the time-dependent radioactive source-term from the Fukushima nuclear power plant accident using atmospheric transport modelling

Caesium-137 and Iodine-131 radionuclides released after the Fukushima Dai-ichi nuclear power plant accident in March 2011 were detected at monitoring stations throughout the world. Using the CTBT radionuclide data and the assumption that the Fukushima accident was the only source of these radionuclides, it was possible to estimate their time-dependent source-term fourteen days following the accident by using atmospheric transport modelling. A reasonable agreement was obtained between the modelling results and the estimated radionuclide release rates from the Fukushima accident.

Uranium, radium and tritium groundwater monitoring at INFN-Gran Sasso National Laboratory, Italy

Uranium groundwater anomalies, which were observed in cataclastic rocks crossing the underground Gran Sasso National Laboratory before the L’Aquila earthquake (April 6th, 2009), have been studied versus radium and tritium contents. The radionuclide analysis supports the role of endogenic fluid dynamics for uranium content in groundwater rather than percolation processes, due to meteoric events occurring above the water table of the Gran Sasso aquifer. The uranium anomalies represent a key geochemical signal of a progressive increase of deep fluids fluxes at middle-lower crustal levels associated with the geodynamics of the earthquake. Moreover, the uranium represents a more precise strain-meter than radon as its presence can be modulated during the preparation phase of the earthquake, and only successively released by microfracturing during the main shock and aftershocks.

Radon gamma-ray spectrometry with YAP:Ce scintillator

The detection properties of a YAP:Ce scintillator (YAlO3:Ce crystal) optically coupled to a Hamamatsu H5784 photomultiplier with standard bialkali photocathode have been analyzed. In particular, the application to radon and radon-daughters gamma-ray spectrometry was investigated. The crystal response has been studied under severe extreme conditions to simulate environments of geophysical interest, particularly those found in geothermal and volcanic areas. Tests in water up to a temperature of 1001C and in acids solutions such as HCl (37%), H2SO4 (48%) and HNO3 (65%) have been performed. The measurements with standard radon sources provided by the National Institute for Metrology of IonizingRadiations (ENEA) have emphasized the non-hyg roscopic properties of the scintillator and a small dependence of the light yield on temperature and HNO3. The data collected in this first step of our research have pointed out that the YAP:Ce scintillator can allow high response stability for radon gamma-ray spectrometry in environments with large temperature gradients and high acid concentrations. r 2002 Elsevier Science B.V. All rights reserved.

Detection of radioxenon in Darwin, Australia following the Fukushima Dai-ichi nuclear power plant accident

A series of (133)Xe detections in April 2011 made at the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) International Monitoring System noble gas station in Darwin, Australia, were analysed to determine the most likely source location. Forward and backwards atmospheric transport modelling simulations using FLEXPART were conducted. It was shown that the most likely source location was the Fukushima Dai-ichi nuclear power plant accident. Other potential sources in the southern hemisphere were analysed, including the Australian Nuclear Science and Technology Organisation (ANSTO) radiopharmaceutical facility, but it was shown that sources originating from these locations were highly unlikely to be the source of the observed (133)Xe Darwin detections.

Estimation of the radioactive source dispersion from Fukushima nuclear power plant accident

Following the Fukushima nuclear power plant accident detections of (133)Xe have been made in various locations. Using results of these remote measurements the Fukushima (133)Xe source term has been reconstructed and compared with previously reconstructed (137)Cs and (131)I source terms. The reconstruction is accomplished by applying atmospheric transport modeling and an adapted least square error method. The obtained results are in agreement with previous estimations of the Fukushima radionuclide source, and also serve as a proof of principle for source term reconstruction based on atmospheric transport modeling.

Monitoring of geochemical and geophysical parameters in the Gran Sasso aquifer

Abstract Since May 1996, groundwater monitoring (for 222 Rn concentration, pH, electrical conductivity, pressure of dissolved gases and temperature) has been carried out at the Gran Sasso National Laboratory of the National Institute of Nuclear Physics using multiparametric equipment. This monitoring scheme has been designed with the aim to better define the geophysical properties of the Gran Sasso aquifer and its radon source(s). The time series analyses show strong anomalies in pH and radon concentrations, highly correlated with the known 1997–1998 Umbria–Marche seismic sequence, which occurred in the central Apennines, Italy.

Uranium Groundwater Monitoring and Seismic Analysis: A Case Study of the Gran Sasso Hydrogeological Basin, Italy

Uranium groundwater anomalies, observed before the L’Aquila earthquake (April 6th, 2009) and before the seismic swarm, which occurred in the second half of 2010, represent a key geochemical signal of a progressive increase of deep fluids fluxes at middle–lower crustal levels associated with the geodynamics of the earthquake. In this paper, temporal variations of uranium groundwater are studied in association with the seismic pattern around Gran Sasso National Laboratory (LNGS-INFN). The normalized seismic energy release and the number of earthquakes are analyzed in detail by means of monthly sliding time windows. They are compared with uranium anomalies to highlight any possible correlation.