Pre-test analysis of protected loss of primary pump transients in CIRCE-HERO facility

In the frame of LEADER project (Lead-cooled European Advanced Demonstration Reactor), a new configuration of the steam generator for ALFRED (Advanced Lead Fast Reactor European Demonstrator) was proposed. The new concept is a super-heated steam generator, double wall bayonet tube type with leakage monitoring [1]. In order to support the new steam generator concept, in the framework of Horizon 2020 SESAME project (thermal hydraulics Simulations and Experiments for the Safety Assessment of MEtal cooled reactors), the ENEA CIRCE pool facility will be refurbished to host the HERO (Heavy liquid mEtal pRessurized water cOoled tubes) test section to investigate a bundle of seven full scale bayonet tubes in ALFRED-like thermal hydraulics conditions. The aim of this work is to verify thermofluid dynamic performance of HERO during the transition from nominal to natural circulation condition. The simulations have been performed with RELAP5-3D© by using the validated geometrical model of the previous CIRCE-ICE test section [2], in which the preceding heat exchanger has been replaced by the new bayonet bundle model. Several calculations have been carried out to identify thermal hydraulics performance in different steady state conditions. The previous calculations represent the starting points of transient tests aimed at investigating the operation in natural circulation. The transient tests consist of the protected loss of primary pump, obtained by reducing feed-water mass flow to simulate the activation of DHR (Decay Heat Removal) system, and of the loss of DHR function in hot conditions, where feed-water mass flow rate is absent. According to simulations, in nominal conditions, HERO bayonet bundle offers excellent thermal hydraulic behavior and, moreover, it allows the operation in natural circulation

Post-test simulation of a PLOFA transient test in the CIRCE-HERO facility

CIRCE is a lead–bismuth eutectic alloy (LBE) pool facility aimed to simulate the primary system of a heavy liquid metal (HLM) cooled pool-type fast reactor. The experimental facility was implemented with a new test section, called HERO (Heavy liquid mEtal pRessurized water cOoled tubes), which consists of a steam generator composed of seven double-wall bayonet tubes (DWBT) with an active length of six meters. The experimental campaign aims to investigate HERO behavior, which is representative of the tubes that will compose ALFRED SG. In the framework of the Horizon 2020 SESAME project, a transient test was selected for the realization of a validation benchmark. The test consists of a protected loss of flow accident (PLOFA) simulating the shutdown of primary pumps, the reactor scram and the activation of the DHR system. A RELAP5-3D© nodalization scheme was developed in the pre-test phase at DIAEE of “Sapienza” University of Rome, providing useful information to the experimentalists. The model consisted to a mono-dimensional scheme of the primary flow path and the SG secondary side, and a multi-dimensional component simulating the large LBE pool. The analysis of experimental data, provided by ENEA, has suggested to improve the thermal–hydraulic model with a more detailed nodalization scheme of the secondary loop, looking to reproduce the asymmetries observed on the DWBTs operation. The paper summarizes the post-test activity performed in the frame of the H2020 SESAME project as a contribution of the benchmark activity, highlighting a global agreement between simulations and experiment for all the primary circuit physical quantities monitored. Then, the attention is focused on the secondary system operation, where uncertainties related to the boundary conditions affect the computational results

Investigation on RELAP5-3D© capability to predict thermal stratification in liquid metal pool-type system and comparison with experimental data

A numerical activity, aimed to evaluate the capability of RELAP5-3D© to reproduce the main thermal-hydraulic phenomena in an HLM pool-type facility, in different operative conditions, is presented. For this purpose, the experimental campaign performed in CIRCE-ICE test facility has been selected for the code assessment. Two experimental tests have been analyzed: TEST A consisting in a transition from no-power to a full power steady state conditions, and TEST I, consisting in a transition from gas-enhanced circulation to natural circulation, simulating a protected loss of heat sink plus a loss of flow accident. Three different pool modelling approaches are presented, consisting in a single vertical pipe, parallel pipes with cross junctions and multi-dimensional component. The comparison with experimental data has highlighted the need to divide the large pool in several sections to reproduce the natural convection, strictly correlated with the thermal stratification. The multi-dimensional component seems to be the best practice for the evaluation of this phenomenon even if the lack of specific correlation for heat transfer coefficient in quasi-stagnant conditions in large tanks is a limit for the accuracy of the results. In addition, the paper presents a detailed nodalization of the fuel pin bundle, highlighting quite good capabilities of RELAP5-3D as a subchannel analysis code

Preliminary neutron kinetic. Thermal hydraulic coupled analysis of the ALFRED reactor using PHISICS/RELAP5-3D

The development of a lead-cooled fast reactor (LFR) demonstrator was proposed, mainly in EU, to investigate the feasibility of an industrial size ELFR (European Lead-cooled Fast Reactor). The demonstrator, called ALFRED (Advanced Lead-cooled Fast Reactor European Demonstrator), consists of a pool-type lead-cooled fast reactor, with a nominal thermal power of 300 MWt. This paper aims to verify the capability of the PHISICS/RELAP5-3D coupled approach to simulate transients of such reactor and to evaluate the effects of accidental scenarios relevant for the safety analysis on the system thermal-hydraulics and on the core power spatial evolution. RELAP5-3D©, developed at Idaho National Laboratory (INL), is a thermal-hydraulic system code, validated for a wide range of transient simulations. The code provides the possibility to simulate innovative working fluids (such as lead and lead alloys) and to use a fully integrated multi-dimensional nodalization. In addition, the need to study complex neutronic systems recommended the development of a new kinetic model allowing the calculation with any number of energy groups and also considering the transport for the angular variations. At this purpose, INL developed PHISICS (Parallel and Highly Innovative Simulation for INL Code System) and its coupling methodology with RELAP5-3D. The simulation activity described in this paper has been focused on the safety analysis of ALFRED reactor assuming the occurrence of two unprotected transient scenarios: unprotected loss of flow (ULOF) and unprotected transient overpower (UTOP). At this purpose, a thermal-hydraulic geometrical scheme of the whole reactor has been developed. The models and the outcomes of the calculations are described and discussed in the paper, highlighting the capability of the coupling approach to obtain results consistent with the ones available in the literature

System thermal-hydraulic modelling of the phénix dissymmetric test benchmark

Phénix is a French pool-type sodium-cooled prototype reactor; before the definitive shutdown, occurred in 2009, a final set of experimental tests are carried out in order to increase the knowledge on the operation and the safety aspect of the pool-type liquid metal-cooled reactors. One of the experiments was the Dissymmetric End-of-Life Test which was selected for the validation benchmark activity in the frame of SESAME project. The computer code validation plays a key role in the safety assessment of the innovative nuclear reactors and the Phénix dissymmetric test provides useful experimental data to verify the computer codes capability in the asymmetric thermal-hydraulic behaviour into a pool-type liquid metal-cooled reactor. This paper shows the comparison of the outcomes obtained with six different System Thermal-Hydraulic (STH) codes: RELAP5-3D©, SPECTRA, ATHLET, SAS4A/SASSYS-1, ASTEC-Na and CATHARE. The nodalization scheme of the reactor was individually achieved by the participants; during the development of the thermal-hydraulic model, the pool nodalization methodology had a special attention in order to investigate the capability of the STH codes to reproduce the dissymmetric effects which occur in each loop and into pools, caused by the azimuthal asymmetry of the boundary conditions. The modelling methodology of the participants is discussed and the main results are compared in this paper to obtain useful guide lines for the future modelling of innovative liquid metal pool-type reactors

Holocene regional gradients of dust provenance and flux between Talos Dome and Dome C, East Antarctica.

Aeolian sequences from Central East Antarctic ice cores provide climate and environmental information of hemispheric significance. Close to the margins of the ice sheet, high-elevation ice-free terrains protruding above the ice sheet surface can provide an additional input of fine dust particles to the atmosphere, making peripheral locations particularly interesting for the study of the regional climate evolution. In the Talos Dome area of East Antarctica, entrainment and transport of local mineral particles is merely influenced by local wind direction and strength, which in turn is tuned by regional climate changes. We investigate the spatial variability of modern and Holocene dust flux, grain size and isotopic (Sr-Nd) composition along a hypothetic transect from Talos Dome all through the interior of the ice sheet (Dome C/Vostok area), and compare the geochemical fingerprint of dust extracted from firn and ice cores to the equivalent size fraction of regolith and glacial deposits from high altitude Victoria Land sources. This study aims to better understand the environmental gradients of dust flux and provenance from the marginal Talos Dome site to the higher Dome C drainage area, with implications for the regional atmospheric circulation, while documenting the isotopic composition of local exposed sediments

Long-Term safety and efficacy of adalimumab in psoriasis. A multicentric study focused on infections (connecting study)

Introduction: This Italian multicenter retrospective study evaluated safety and efficacy of the anti-TNF drug, adalimumab, in a cohort of patients affected by tuberculosis (TB), hepatitis B virus (HBV), hepatitis C virus (HCV) or human immunodeficiency virus (HIV). Psoriasis is an autoimmune disease affecting around 3% of the Italian population and associated with several comorbidities, including arthritis, cardio-metabolic diseases and depression. In its moderate-To-severe form, psoriasis profoundly impairs quality of life of patients. Aim: Therefore, these patients deserve systemic treatments including conventional DMARDS (disease modifying anti-rheumatic drugs) and biologics. Management of moderate and severe psoriasis patients affected by relevant infections such as TB, HBV, HCV and HIV may be difficult because of the toxicity of the conventional systemic treatment. Material and methods: The CONNECTING study analysed 28 moderate to severe psoriasis patients infected by TB, HBV, HCV and HIV who were treated with adalimumab for up to 96 weeks together with respective prophylactic treatment. Results: We observed a rapid decrease in PASI (psoriasis area severity index) reaching a 75% improvement in 91% of patients. Some of these patients (n = 9) were also affected by arthritic comorbidity. The patients experienced a rapid decrease in pain, measured by pain VAS (visual analogic scale) that reached 0 in all of them. Monitoring of the respective infection did not show any worsening or reactivation of infection or any severe adverse events during the entire observation period. Conclusions: Adalimumab is effective and safe in patients affected by these important infections

Sorting living mesenchymal stem cells using a TWIST1 RNA-based probe depends on incubation time and uptake capacity

Bone marrow derived mesenchymal stromal cells (BMSCs) are multipotent progenitors of particular interest for cell-based tissue engineering therapies. However, one disadvantage that limit their clinical use is their heterogeneity. In the last decades a great effort was made to select BMSC subpopulations based on cell surface markers, however there is still no general consensus on which markers to use to obtain the best BMSCs for tissue regeneration. Looking for alternatives we decided to focus on a probe-based method to detect intracellular mRNA in living cells, the SmartFlare technology. This technology does not require fixation of the cells and allows us to sort living cells based on gene expression into functionally different populations. However, since the technology is available it is debated whether the probes specifically recognize their target mRNAs. We validated the TWIST1 probe and demonstrated that it specifically recognizes TWIST1 in BMSCs. However, differences in probe concentration, incubation time and cellular uptake can strongly influence signal specificity. In addition we found that TWIST1high expressing cells have an increased expansion rate compared to TWIST1low expressing cells derivedfrom the same initial population of BMSCs. The SmartFlare probes recognize their target gene, however for each probe and cell type validation of the protocol is necessary

Чергове засідання Ради Міжнародної асоціації академій наук

7 червня 2012 року в Національному дослідницькому центрі «Курчатовський інститут» відбулося чергове засідання Ради Міжнародної асоціації академій наук (МААН). Під час урочистої церемонії закриття засідання президенту МААН, президенту НАН України академіку НАН України і РАН Борису Євгеновичу Патону було присвоєно звання Почесного доктора НДЦ «Курчатовський інститут»

The impact of biologic therapy for moderate-to-severe psoriasis on the immune responses to SARS-CoV2 infection and vaccination

Dear Editor, we explored the impact of biologics and conventional therapies for psoriasis on humoral and T-cellular responses to SARS-CoV-2 infection and vaccine. The study (EUDRA 2020-004965-37 Humanitas ICH Ethic Committee) was conducted at the Istituto Clinico Humanitas-Rozzano, Milan, and at the University of Verona, Italy. The enrolled patients were affected by moderate-to-severe psoriasis and were divided into two groups: those who had developed COVID-19 infection (group 1, n=95) and those who underwent COVID-19 vaccination (group 2, n=77