New high-throughput measurement systems for radioactive wastes segregation and free release

Comparison of MCC-MT and EffMAKER software packages for in SITU field measurements with Monte Carlo simulations

This work is devoted to comparing the Monte Carlo simulation tools: Monte Carlo Calculation-Multi Track (MCC-MT) software and EffMaker software, in terms of the efficiency when using them in field applications for measurement of radioactive waste or their free release from control. The detection efficiency of volumetric gamma sources' reference samples in the form of a metal cylinder, a rod, and a rod placed in a 200-L barrel with sand, in the energy range of 50-1500 keV, has been simulated. Comparison of simulation results with in-situ measurements by a mobile HPGe spectrometer showed that the discrepancy between calculation and experiment for all measurement geometries is larger for EffMaker, which is associated with a less accurate detector model than in MCC-MT. Both programs give acceptable results in terms of accuracy and are recommended for calibrating gamma spectrometers in the case of field measurements.

Validation of a free release measurement facility on a decommissioning site

The paper summarizes measurements and the Monte Carlo simulations performed to adapt the high purity germanium (HPGe) detectors of the system to the particular tasks of the decommissioning site. The work carried out for the installation and adaptation in CIEMAT of the prototype 'SuperMum', developed in the framework of the European MetroDecom II project for segregation and declassification of materials is described. The activities related to the validation of the prototype for the specific needs of a real Waste Management Unit are presented. Monte Carlo models of the SuperMum have been developed at CIEMAT and CMI using different codes and adapted to the geometries used (big-bag containers with the material volume of up to 0.5 m³). Uncertainty budget reporting tailored for the possible deviations between Monte Carlo assumptions and real waste have been analyzed. Data for several filling levels and activity distributions have been measured with reference sources and a good agreement has been obtained with calculated values.

Substrate Specificity of SARS-CoV-2 Nsp10-Nsp16 Methyltransferase

The ongoing COVID-19 pandemic exemplifies the general need to better understand viral infections. The positive single-strand RNA genome of its causative agent, the SARS coronavirus 2 (SARS-CoV-2), encodes all viral enzymes. In this work, we focused on one particular methyltransferase (MTase), nsp16, which, in complex with nsp10, is capable of methylating the first nucleotide of a capped RNA strand at the 2′-O position. This process is part of a viral capping system and is crucial for viral evasion of the innate immune reaction. In light of recently discovered non-canonical RNA caps, we tested various dinucleoside polyphosphate-capped RNAs as substrates for nsp10-nsp16 MTase. We developed an LC-MS-based method and discovered four types of capped RNA (m⁷Gp₃A(G)- and Gp₃A(G)-RNA) that are substrates of the nsp10-nsp16 MTase. Our technique is an alternative to the classical isotope labelling approach for the measurement of 2′-O-MTase activity. Further, we determined the IC₅₀ value of sinefungin to illustrate the use of our approach for inhibitor screening. In the future, this approach may be an alternative technique to the radioactive labelling method for screening inhibitors of any type of 2′-O-MTase.

Metrology for decommissioning nuclear facilities: Partial outcomes of joint research project within the European Metrology Research Program

Decommissioning of nuclear facilities incurs high costs regarding the accurate characterisation and correct disposal of the decommissioned materials. Therefore, there is a need for the implementation of new and traceable measurement technologies to select the appropriate release or disposal route of radioactive wastes. This paper addresses some of the innovative outcomes of the project "Metrology for Decommissioning Nuclear Facilities" related to mapping of contamination inside nuclear facilities, waste clearance measurement, Raman distributed temperature sensing for long term repository integrity monitoring and validation of radiochemical procedures.