The role played by DNA cluster damage and chromosome aberrations in radiation-induced cell killing was investigated, assuming that certain chromosome aberrations (dicentrics, rings and large ...deletions, or 'lethal aberrations') lead to clonogenic inactivation and that chromosome aberrations are due to micrometre-scale rejoining of chromosome fragments derived from DNA cluster lesions (CLs). The CL yield and the threshold distance governing fragment rejoining were left as model parameters. The model, implemented as a Monte Carlo code called BIANCA (BIophysical ANalysis of Cell death and chromosome Aberrations), provided simulated survival curves that were compared with survival data on AG1522 and V79 cells exposed to different radiation types, including heavy ions. The agreement between simulation outcomes and experimental data suggests that lethal aberrations are likely to play an important role in cell killing not only for AG1522 cells exposed to X rays, as already reported by others, but also for other radiation types and other cells. Furthermore, the results are consistent with the hypothesis that the critical DNA lesions leading to cell death and chromosome aberrations are double-strand break clusters (possibly involving the ∼1000-10 000 bp scale) and that the effects of such clusters are modulated by micrometre-scale proximity effects during DNA damage processing.
With reference to the prototype of neutron inspection portal built and successfully tested in the Rijeka seaport (Croatia) within the EURITRACK (EURopean Illicit Trafficking Countermeasures Kit) ...project, an assessment of the biological shielding in different set-up configurations of a future portal has been calculated with MCNP Monte Carlo code in the frame of the Eritr@C (European Riposte against Illicit TR@ffiCking) project. In the configurations analyzed the compliance with the dose limits for workers and the population stated by the European legislation is provided by appropriate shielding of the neutron sources and by the delimitation of a controlled area.
► We assess the biological shielding of a inspection portal based on neutron sources. ► Different configurations of the system have been calculated with MCNP code. ► The work has been performed within the European Eritr@C project. ► The compliance with the European dose limits has been verified for each configuration. ► It is provided by shielding of the neutron sources and by delimitation of a controlled area.
The radiological risk for the population related to the neutron irradiation of cargo containers with a tagged neutron inspection system has been studied. Two possible effects on the public health ...have been assessed: the modification of the nutritional and organoleptic properties of the irradiated materials, in particular foodstuff, and the neutron activation of consumer products (i.e. food and pharmaceuticals). The result of this study is that irradiation of food and foodstuff, pharmaceutical and medical devices in container cargoes would neither modify the properties of the irradiated material nor produce effective doses of concern for public health. Furthermore, the dose received by possible stowaways present inside the container during the inspection is less than the annual effective dose limit defined by European Legislation for the public.
► Neutron irradiation of cargo containers implies a radiological risk. ► The risk is about the modification of food properties and the products activation. ► Assessment is made about the EURITRACK neutron irradiation system. ► Results show that the EURITRACK scanning is not dangerous for the population.
The ARGO-YBJ experiment is an air shower detector for gamma ray astronomy and cosmic ray studies with an energy threshold of ∼500 GeV. Working in “single particle mode”, i.e. counting the single ...particles hitting the detector at fixed time intervals, ARGO-YBJ can monitor cosmic ray and gamma ray transients at energies of a few GeV.
The single particle counting rate is modulated by the atmospheric pressure and temperature, and is affected by the local radioactivity from soil and air. Among the radioactive elements, radon gas is of particular importance since its concentration in air can vary significantly, according to environmental conditions. In this paper we evaluate the contribution of the radon daughter gamma ray emitters to the single particle counting rate measured by ARGO-YBJ. According to our analysis, the radon gas contribution is roughly 1–2%, producing a counting rate modulation of the same order of magnitude of the atmospheric effects.
•The ARGO-YBJ experiment is an air shower detector for gamma ray astronomy of very large area.•The ARGO-YBJ detector can work into two modes: single particle mode and shower mode.•The work shows how natural radioactivity can influence the single particle counting.•The paper shows how to evidence (and correct) the radon influence on the detector counting.
ARGO-YBJ is an extensive air shower detector located at the Yangbajing Cosmic Ray Laboratory (4300 m a.s.l., 606 g cm-2 atmospheric depth, Tibet, China). It is made by a single layer of Resistive ...Plate Chambers (RPCs, total surface ~6700 m2 ) grouped into 153 units called "clusters". The low energy threshold of the experiment is obtained using the "scaler operation mode", counting all the particles hitting the detector without reconstruction of the shower size and arrival direction. For each cluster the signals generated by these particles are put in coincidence in a narrow time window (150 ns) and read by four independent scaler channels, giving the counting rates of channel ≥1, ≥2, ≥3 and ≥4 hits. The study of these counting rates pointed out a different behavior of channel ≥1 respect to the higher multiplicity channels: while the MC simulations can account fairly well for the coincident counting rates, the expectation for channel ≥1 is sensibly less than the measured value. Moreover, the regression coefficient with the atmospheric pressure for channel ≥1 is also about half of the value measured for the coincident counting rates: seemingly half of these counts did not cross the atmosphere.Measurements of the natural radioactivity background in the air of the detector hall and a MC simulation to estimate its contribution on our counting rates are presented and discussed.
In recent years, many cases of contamination of metal scraps by unwanted radioactive materials have occurred. Moreover, international organisations are evaluating the possibility to re-use or to ...recycle metals coming from nuclear power plants. The metal recycling industry has started to worry about radiation exposure of workers that could be in contact with contaminated metals during each manufacturing phase. Risks are strongly dependent on the radiation source features. The aim of this study is to perform risk assessment for workers involved in chemical pickling of steel coils. Monte Carlo simulations have been performed, using the MCNP package and considering coils contaminated with 60Co, 137Cs, 241Am and 226Ra. Under the most conservative conditions (coil contaminated with 1.0 kBq g−1 of 60Co), the dose assessment results lower than the European dose limit for the population (1 mSv y−1), considering a maximum number of 10 contaminated coils handled per year. The only exception concerns the case of 241Am, for which internal contamination could be non- negligible and should be verified in the specific cases. In every case, radiation exposure risk for people standing at 50 m from the coil is widely <1 mSv y−1.
