Eduardo Gallego

The response of a scintillation neutron detector of ZnS(Ag) with (10)B was calculated, using the MCNPX Monte Carlo Code. The detector consists of four panels of polymethyl methacrylate (PMMA) and five thin layers of ~0.017cm thick (10)B+ZnS(Ag) in contact with the PMMA. The response was calculated for the bare detector and with different thicknesses of High Density Polyethylene, HDPE, moderator for 29 monoenergetic sources as well as (241)AmBe and (252)Cf neutrons sources. In these calculations the reaction rate (10)B(n, α)(7)Li and the neutron fluence in the sensitive area of the detector (10)B+ZnS(Ag) was estimated. Measurements were made at the Neutron Measurements Laboratory, Universidad Politécnica de Madrid, LMN-UPM, to quantify the detections in counts per second in response to a (252)Cf neutron source separated 200cm. The MCNPX computations were compared with measurements to estimate the efficiency of ZnS(Ag) for detecting the α that is created in the (10)B(n, α)(7)Li reacti...

In this report, the Commission provides guidance for the protection of people living in long-term contaminated areas resulting from either a nuclear accident or a radiation emergency. The report considers the effects of such events on the affected population. This includes the pathways of human exposure, the types of exposed populations, and the characteristics of exposures. Although the focus is on radiation protection considerations, the report also recognises the complexity of post-accident situations, which cannot be managed without addressing all the affected domains of daily life, i.e. environmental, health, economic, social, psychological, cultural, ethical, political, etc. The report explains how the 2007 Recommendations apply to this type of existing exposure situation, including consideration of the justification and optimisation of protection strategies, and the introduction and application of a reference level to drive the optimisation process. The report also considers ...

This paper describes the evaluation module in the MOIRA system, which is a decision support system based on a multi-attribute additive value model, aim at the identification of optimal remedial strategies restoration of aquatic ecosystems contaminated by radio- nuclides. It includes facilities for assessing imprecise scalar utility functions and scaling factors, as well as a sensitivity analysis tool to check the sensitivity of the conclusions to the inputs, to allow the decision makers to gain insights into the problem. An example based on real data illustrates the usefulness of the system.

INTRODUCCIÓN La radiactividad es uno de los grandes descubrimien-tos del hombre contemporáneo. A la par que se fueron conociendo sus efectos también se fueron encontran-do aplicaciones de gran utilidad, en las que las sustan-cias radiactivas o los aparatos emisores de radiaciones ionizantes resultan insustituibles. Además de la medi-cina, la agricultura, la industria, las ciencias de la tie-rra, la biología y otras muchas ramas dependen hoy en día en muchos aspectos de su utilización. Este trabajo introduce la naturaleza de las sustancias radiactivas y de la radiación ionizante, los efectos que esta causa sobre la materia y los medios disponibles para su detección y medida, así como las diferentes fuentes de radiación naturales a las que los seres hu-manos estamos expuestos. Seguidamente, en el aparta-do más amplio del trabajo, se describen las múltiples aplicaciones de las radiaciones ionizantes para poder poner su impacto en perspectiva frente al de las fuen-tes naturales. La tesi...

An automated panoramic irradiator with a 3 Ci 241Am-Be neutron source is installed in a bunker-type large room at the Universidad Politécnica de Madrid (UPM). It was recently modified and a neutron spectrometry campaign was organized to characterize the neutron fields in different measurement points along the irradiation bench. Four research groups working with different Bonner Sphere Spectrometers (BSS) and using different spectral unfolding codes took part to this exercise. INFN–LNF used a BSS formed by 9 spheres plus bare detector, with cylindrical, almost point like, 6LiI(Eu) scintillator (4 mm x 4 mm, from Ludlum); UAZ-UPM employed a similar system but with only 6 spheres plus bare detector; UAB worked with a 3He filled proportional counter at 8kPa filling pressure, cylindrical 9 mm x 10 mm (05NH1 from Eurisys) with 11 spheres configuration; and CIEMAT used 12 spheres with an spherical 3He SP9 counter (Centronic Ltd., UK) with very high sensitivity due to the large diameter (3....

The response matrix of a Bonner sphere spectrometer was calculated using MCNP 4C and MCNPX 2.4.0 codes. As thermal neutron detector a 0.4 cm x 0 0.4 cm (LiI)-Li-6 which is located at the center of a set of polyethylene spheres. The response was calculated for 0, 2, 3, 5, 8, 10, and 12 inches-diameter polyethylene spheres for neutrons whose energy goes from 2.50E(-8) to 100 MeV The response matrix was calculated for 23 neutron energies, the response functions were energy-interpolated to 51 neutron energies and were compared with a matrix response reported in the literature, in this comparison both response matrices are in agreement. The main differences were found in the bare detector and are attributed to the irradiation conditions and cross sections, for the other detectors the differences are due to the cross sections libraries.

When linacs operate above 8MV an undesirable neutron field is produced whose spectrum has three main components: the direct spectrum due to those neutrons leaking out from the linac head, the scattered spectrum due to neutrons produced in the head that collides with the nuclei in the head losing energy and the third spectrum due to room-return effect. The third category of spectrum has mainly epithermal and thermal neutrons being constant at any location in the treatment hall. These neutrons induce activation in the linac components, the concrete walls and in the patient body. Here the induced radioisotopes have been identified in concrete samples located in the hall and in one of the wedges. The identification has been carried out using a gamma-ray spectrometer.

Using an analysis of the way European newspapers covered the Fukushima nuclear accident, this article explores how the mass media transmit information about radiation risks from experts to the general public. The study applied a media content analysis method on a total of 1340 articles from 12 leading newspapers in 6 countries: Belgium (N = 260), Italy (N = 270), Norway (N = 133), Russia (N = 172), Slovenia (N = 190) and Spain (N = 315). All articles analysed were selected as being directly or indirectly related to the Fukushima accident by containing the word 'nuclear' and/or 'Fukushima' and were published between the 11th March and the 11th May 2011. The data presented here focus specifically on a cross-cultural comparison of the way the media use quantitative units. Results suggest that although experts are accustomed to communicating about radiological risks in technical language, often using quantitative units to describe the risks, mass media do not tend to use...

Radiotherapy methods have been substantially improving during the last years. Nevertheless, the patients' risk, as consequence of the radiation used in the treatment, keeps being of important concern. In particular, the peripheral dose, usually from photons and neutrons in conventional therapy with linacs, represents an important topic to study. The objective is to provide an adequate radiation protection to the patient, that allow to evaluate the best strategy for treatment and take into account the risk-benefit balance due to the out-of-field dose delivered. Although photon doses have been deeply contemplated, the neutron contamination from high energy photon beams is still a subject of research and discussion. In the present work, we introduce a new digital device that permits real time evaluation of the equivalent dose in organs during any therapeutic session. For this purpose, we have obtained a huge experimental data collection, considering different photon energies, linac...

During the last ten years new trends in deterministic and probabilistic safety analysis have been developed. The main part of the new methodologies is motivated by the Generation IV reactors evaluation. In those reactors, the concepts of safety margins that apply to the light water reactors are not directly applicable, needing a different definition of the safety limits. The new methodologies have been created to give an adequate framework for the licensing and evaluation process of the advanced reactors. The aim of this paper is to give an overview of the new trends in the integration of deterministic and probabilistic safety analysis methodologies for the Generation IV reactors. Therefore, it will be described the experience from the participation of the UPM in several international projects that were raised to develop and assess the new methodologies Some of those projects are: NEA/OECD Safety Margin Applications and Assessment (SM2A), SARNET European Project, SARGEN-IV European ...

ABSTRACT The properties as a neutron detector of a silicon photodiode of type Hamamatsu S3590-02 in conjunction with a multi-channel analyser Alphatron-3C were investigated in an 241 Am-7 Be calibration field at the department of nuclear engineering at the University of Madrid. Since the photodiode is sensitive to charged particles, we covered it with two types of converters to enable its response to thermal and fast neutrons. To detect thermal neutrons a 2mm thick 6 LiF converter deposited on aluminium support was used. The detector was placed in the centre of a 25 cm diameter paraffin sphere in front of the neutron source. The response of detector with the 6 LiF converter (understood as the integrated peak count of the alphas produced in the reaction of the Li with thermal neutrons) was compared with the response of a calibration neutron dose rate probe as well as with the more accurate ambient dose equivalent rate based on spectrometric measurements of the calibration field. Good correlation between the detector response and the calibration measurements was found and the calibration coefficient of the silicon detector was determined. For the detection of fast neutrons, a polyethylene converter of 2 mm was employed in order to produce recoil protons. Initially, numerical simulations were performed to predict the efficiency of detection and the shape of the energy spectrum of the recoil protons produced in response to the neutrons emitted by the bare Am-Be source. Subsequently, measurements with the source were carried out in order to determine the sensitivity and applicability of the detector to detect fast neutrons. The counting rate as a function of distance and the angular characteristics of the detector were also determined. We discuss the possibilities of using such a photodiode as a neutron dosimeter.