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

Molecular Cause and Functional Impact of Altered Synaptic Lipid Signaling Due to a \u3cem\u3eprg-1\u3c/em\u3e Gene SNP

Loss of plasticity‐related gene 1 (PRG‐1), which regulates synaptic phospholipid signaling, leads to hyperexcitability via increased glutamate release altering excitation/inhibition (E/I) balance in cortical networks. A recently reported SNP in prg‐1 (R345T/mutPRG‐1) affects ~5 million European and US citizens in a monoallelic variant. Our studies show that this mutation leads to a loss‐of‐PRG‐1 function at the synapse due to its inability to control lysophosphatidic acid (LPA) levels via a cellular uptake mechanism which appears to depend on proper glycosylation altered by this SNP. PRG‐1+/− mice, which are animal correlates of human PRG‐1+/mut carriers, showed an altered cortical network function and stress‐related behavioral changes indicating altered resilience against psychiatric disorders. These could be reversed by modulation of phospholipid signaling via pharmacological inhibition of the LPA‐synthesizing molecule autotaxin. In line, EEG recordings in a human population‐based cohort revealed an E/I balance shift in monoallelic mutPRG‐1 carriers and an impaired sensory gating, which is regarded as an endophenotype of stress‐related mental disorders. Intervention into bioactive lipid signaling is thus a promising strategy to interfere with glutamate‐dependent symptoms in psychiatric diseases

Single-molecule in vivo imaging of bacterial respiratory complexes indicates delocalized oxidative phosphorylation

Chemiosmotic energy coupling through oxidative phosphorylation (OXPHOS) is crucial to life, requiring coordinated enzymes whose membrane organization and dynamics are poorly understood. We quantitatively explore localization, stoichiometry, and dynamics of key OXPHOS complexes, functionally fluorescent protein-tagged, in Escherichia coli using low-angle fluorescence and superresolution microscopy, applying single-molecule analysis and novel nanoscale co-localization measurements. Mobile 100-200nm membrane domains containing tens to hundreds of complexes are indicated. Central to our results is that domains of different functional OXPHOS complexes do not co-localize, but ubiquinone diffusion in the membrane is rapid and long-range, consistent with a mobile carrier shuttling electrons between islands of different complexes. Our results categorically demonstrate that electron transport and proton circuitry in this model bacterium are spatially delocalized over the cell membrane, in stark contrast to mitochondrial bioenergetic supercomplexes. Different organisms use radically different strategies for OXPHOS membrane organization, likely depending on the stability of their environment

Confirmation of 20 % error in the 209Po half-life

First results of a half-life measurement of 209Po show 20% discrepancy with the formerly recommended value of 102 (5) years, which was based on a single experiment performed in 1956. The preliminary value obtained in this work, 123.2 (55) years, confirms the newly determined value of 125.2 (33) years by Collé et al. (2014) based on the observation of inconsistencies in decay-corrected activity measurements of a 209Po solution over time. The error in the half-life has an impact on numerous measurements in which aged 209Po solutions were used as a tracer.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

The 55Fe half-life measured with a pressurised proportional counter

The half-life of 55Fe has been measured accurately by following the decay curve of three sources with a large pressurised proportional counter. An argon(90%)-methane(10%) mixture was used as counter gas, at atmospheric pressure (∼1 × 105 Pa) and at enhanced pressures of 5 × 105 Pa and 8 × 105 Pa (for 1 source), respectively. The first measurements were performed in 2001, but the experiment was executed more systematically between 2005 and 2018, covering a period of about 5 half-lives. The residuals from an exponential decay curve were of the order of 0.1% to 0.2% at 1 × 105 Pa, and 0.03% at 5 × 105 Pa and 8 × 105 Pa. The gain of stability with increased gas pressure was due to asymptotically reaching the maximum counting efficiency, resulting in lower sensitivity to pressure variations. The deduced half-life value of T1/2(55Fe) = 1006.70 (15) d or 2.7563 (4) a is more accurate than other data in literature, which are mutually discrepant. It is consistent with previous measurements at JRC with an X-ray defined solid angle counter.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard

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

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

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

Measurement of anthropogenic radionuclides in post-Fukushima Pacific sea water samples

Following the accident at the Dai-ichi Fukushima nuclear power plant in 2011, a vast number of Pacifîc sea water samples from many locations far from Fukushima have been collected by Japanese investigators. Due to dilution, the activities of radionuclides from North Pacifîc sea water samples are very low, which calls for extraordinary measures when being measured. This paper focusses 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 multi-detector systems and well-detectors. Optimization of detection limits for different radionuclides and detectors were performed using Monte Carlo simulations.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard