Measurements of 60Co in Massive Steel Samples Exposed to the Hiroshima Atomic Bomb Explosion

In order to help solving discrepancies in retrospective Hiroshima dosimetry, sixteen steel samples from Hiroshima were measured in the underground laboratory HADES. The aim was to measure the specific activity of 60Co. Although it was found that activities at long range (> 1300 m slant range) were mainly cosmogenically induced, the activities were so low that former measurements that were 10 to 100 times higher than predicted by computer model calculations in DS86 and DS02 could be refuted. As a consequence, the confidence in the existing dose estimates has become stronger.JRC.DG.D.5-Nuclear physic

JRC Serving policy & science at the HADES underground research facility - a casebook: Interdisciplinary nuclear science applications performed by JRC-Geel in a 225 m deep underground, low-background radioactivity lab

JRC has developed and performed ultra low background measurements of radioactivity in undeground laboratories since 1992. What started as an exploratory research projects has grown into a successful infrastructure supporting uncountable JRC projects and external stakeholders. This report seek to give a brief overview and understanding for the many interdisciplinary nuclear science applications that have benefited from JRC's measurements of radioactivity in the underground research facility HADES over the past 20 years.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard

Evaluation of the 2017 EC Proficiency Test on 131I, 134Cs and 137Cs in maize powder

A proficiency test (PT) on the measurements of I-131, Cs-134 and Cs-137 in maize powder was organised by European Commission Directorate-General (EC DG) Joint Research Centre in Geel on request of the EC DG for Energy. This PT was an integral part of the EC's work of realising verification of Member State's obligations towards Article 35 of the Euratom Treaty. It serves also as a quality control programme which JRC-Geel is coordinating in order to assess the quality of the results collected in the Radioactivity Environmental Monitoring (REM) database. The PT reference material was prepared by spiking blank maize powder. The samples were sent to 123 laboratories of which 120 laboratories submitted their results. The evaluation of the PT results was performed according to ISO 13528:2015. The zed (z) and zeta (ζ) and En scores, were calculated. The z scores of the reported results for I-131 were acceptable for 92% of laboratories. For both Cs-134 and Cs-137 they were acceptable for 94% laboratories. The ζ scores were satisfactory for 66%, 56% and 68% of results for I-131, Cs-134 and Cs-137 respectively. In case of En score the number of consistent results was the same as for ζ score.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard

DONA Detector: Further Improvements and Evaluation for Field Applications

The DONA neutron spectrometer concept is based on the measurement of neutron induced activity in a series of small metal disks that have been exposed to a neutron field. The induced activity is measured and the neutron spectrum is calculated using and unfolding technique, based on environmental neutron spectra. The novelty of the approach lies in the concept as such, including usage of carefully selected metal disks arranged in a holder, high performance gamma-ray spectrometry and spectrum unfolding using a library of environmental neutron spectra. This report covers the IRMM exploratory research prolongation project for 2006 and now environmental neutron fields with considerably lower neutron fluence rates are used. The result shows that after further refinement of the detector device and the data evaluation program the detector can very well be used for environmental neutron fluence measurements. Tests were done at PTB, Germany, using their calibrated neutron source and at the MOX fuel fabrication plant Belgonuclearire in Mol, Belgium.JRC.D.4-Isotope measurement

Status of Underground Radioactivity Measurements in HADES

The IRMM (Institute for Reference materials and Measurements) performs ultra low-level gamma-ray spectrometry at a depth of 225 m in the underground laboratory HADES. The facility currently houses 7 HPGe-detectors that are built and shielded using specially selected radiopure materials. The sandclay overburden of about 500 m water equivalent assures a muon flux reduction factor of about 5000, with subsequent reduction of the background of the detectors, which makes it possible to obtain detection limits close to 100 µBq for certain radionuclides. This paper describes the aim of the IRMM activities in the HADES laboratory, the equipment and the measurement program and gives examples of radiopurity measurements carried out in order to develop better low-level measurements.JRC.DG.D.5-Nuclear physic

Underground gamma-ray measurements of radium isotopes from hydrothermal plumes in the deep Pacific Ocean

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hult, M., Charette, M., Lutter, G., Marissens, G., Henderson, P., Sobiech-Matura, K., & Simgen, H. Underground gamma-ray measurements of radium isotopes from hydrothermal plumes in the deep Pacific Ocean. Applied Radiation and Isotopes, 153, (2019): 108831, doi:10.1016/j.apradiso.2019.108831.The radium isotopes 226Ra and 228Ra can provide important data on the dynamics of deep-sea hydrothermal plumes that travel the oceans for decades and have great impact on the ocean chemistry. This study focuses on parameters important for obtaining low detection limits for 228Ra using gamma-ray spectrometry. It is present at mBq-levels in samples collected during the US GEOTRACES 2013 cruise to the Southeast Pacific Ocean.The work of the HADES-staff of Euridice at SCK•CEN is gratefully acknowledged. We are most grateful to Dr. Faidra Tzika for her work in the precursor to this project. Many thanks to Heiko Stroh for quality control and measurements in HADES. This research was supported in part by grants from the U.S. National Science Foundation, Ocean Sciences division (OCE-1232669 and OCE-1736277)

Comprehensive study on the technical aspects of sampling, transporting and measuring radon-in-water

The European Commission`s Joint Research Centre organizes proficiency tests (PT) on radon-in-water measurements. In order to optimize sampling, transport and measurement methods many tests and small scale proficiency tests have been performed. The waters from natural springs, wells were sampled on-site in glass bottles then transported cooled to the JRC and collaborating laboratories. For the material characterization standard measurement methods based on gamma-ray spectrometry, emanometry and liquid scintillation counting were used. The influence of sampling, transport and sample handling on radon-loss was tested and quantified. It was observed that parameters like container material, filling height, storage temperature and handling can lead to substantial measurement bias due to radon-loss. This high risk for radon-loss from samples can potentially be a general radioprotection problem as doses to the public may be underestimated. Regular air and road transport can be considered adequate means of transport as they have little influence on radon-loss if a suitable glass sample container with flexible cap is used and that it is completely filled. On the basis of this work, modifications to the related standard as best practices are also proposed.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard

A gamma-ray spectrometry analysis software environment

At the JRC-Geel's RadioNuclide Metrology sector, a Monte Carlo code based on EGSnrc, and a general purpose calculation sheet implemented in Microsoft Excel®, have been developed to make the quantitative gamma-ray spectrometry analysis of samples simpler and more robust. The further aim is that the software can be used by non-experts in gamma-ray spectrometry e.g. external researchers using JRC-Geel’s facilities through the EUFRAT transnational access scheme. This paper presents the developed Monte Carlo software and the functionality included in the calculation sheet.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard

Characterisation of an ultra low-background point contact HPGe well-detector for an underground laboratory

Since a few years there are well-type HPGe-detectors with a small, point-like, anode contacts available commercially. This paper describes the characterisation of the first ultra low-background, so-called, SAGe™ well detector with regards to resolution and background performance. Inside a passive lead/copper shield in the underground laboratory HADES a background count rate of 690 ± 6 d−1 (268 ± 3 d−1 per kg Ge) was recorded 19 months after taking it underground.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard