319 research outputs found

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

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    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the validated geometrical model of the previous CIRCE-ICE test section [2], in which the preceding heat exchanger has been replaced by the new bayonet bundle model.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

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    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

    System thermal-hydraulic modelling of the phénix dissymmetric test benchmark

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    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

    Use of biological drugs in patients with psoriasis and psoriatic arthritis in italy: Results from the PSONG survey

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    This Italian multicenter retrospective study compared the drug survival and efficacy of differentanti-TNF agents in psoriasis (PsO) and psoriatic arthritis (PsA) patients. A database of PsO/PsApatients treated with adalimumab, etanercept, and infliximab from May 2013 to May 2014 wasanalyzed. PASI 75, 90, and 100 was calculated at each time point to evaluate efficacy. Drug sur-vival rate and probability of maintaining PASI response were evaluated. The impact of dependentvariables on probability of PASI 75 loss was evaluated by logistic regression. 1,235 patients wereincluded, 577 with PsO and 658 with PsA. Highest survival rates were observed with adalimumabfollowed by etanercept and infliximab in PsO and PsA patients. The probability of maintainingPASI response was significantly higher for adalimumab followed by infliximab. For PsO patients,the odds of losing PASI 75 was higher in etanercept-treated patients (OR: 8.1; 95% CI: 4.2–15.6,p<.001) or infliximab (OR: 6.6; 95% CI: 2.6–16.3,p<.001) vs. adalimumab. Likewise, for PsApatients the odds of losing PASI 75 was higher in etanercept-treated patients (OR: 2.3; 95% CI:1.4–3.8,p5.01) or infliximab (OR: 2.2; 95% CI: 1.1–4.1,p5.018) vs. adalimumab. Adalimumabcould be the best therapeutic option over other anti-TNF agents for the treatment of PsO and PsApatients

    A Case of Ketron-Goodman Disease

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    Pagetoid reticulosis (PR) is a rare form of cutaneous T-cell lymphoma [Mod Pathol 2000;13:502–510]. Two variants of the disease are described: the localized type Woringer-Kolopp disease (WKD) and the disseminated type Ketron-Goodman disease (KGD). KGD may have disseminated lesions, high rate of recurrence and a guarded prognosis [Mod Pathol 2000;13:502–510]. In patients with KGD, therefore, long-term observation is necessary. Disappearance of cutaneous lesions does not mean resolution of the disease [J Am Acad Dermatol 2002;47:183–186]. Herein we report the case of an 84-year-old man with erythematous patches of the trunk and the upper and lower extremities in whom the diagnosis of KGD was made. We describe this case for the rarity of this pathology and for the good response to therapy (IFN)

    Wells Syndrome with Multiorgan Involvement Mimicking Hypereosinophilic Syndrome

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    Eosinophil-associated diseases represent a spectrum of heterogeneous disorders, where blood and cutaneous eosinophilia is the most important feature and eosinophils are the principal cause of cutaneous lesions. These diseases show some similarities in the clinical features but also many distinctive characteristics [Saurat et al., Dermatologia e malattie sessualmente trasmesse, Milano, Masson, 2000]. Wells syndrome is one of these disorders and is an uncommon recurrent inflammatory dermatosis, rarely associated to signs and symptoms of multiple organ involvement [Arch Dermatol 2006;142:1157–1161]. Hypereosinophilic syndrome, in contrast, constitutes a group of idiopathic disorders characterized by blood eosinophilia for at least 6 months, associated with single or multiple organ system dysfunction [Arch Dermatol 2006;142:1157–1161]. Clinically atypical Wells syndrome with multiorgan involvement is reported here. A correct diagnosis is difficult in this case, but clinical and histopathological features are compatible with this diagnosis. The reported condition likely represents a borderline hypereosinophilic disease, in which clinical features of both hypereosinophilic syndrome and Wells syndrome are present

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

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    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

    Silencing of anti-chondrogenic microRNA-221 in human mesenchymal stem cells promotes cartilage repair in vivo

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    There is a growing demand for the development of experimental strategies for efficient articular cartilage repair. Current tissue engineering-based regenerative strategies make use of human mesenchymal stromal cells (hMSCs). However, when implanted in a cartilage defect, control of hMSCs differentiation towards the chondrogenic lineage remains a significant challenge. We have recently demonstrated that silencing the anti-chondrogenic regulator microRNA-221 (miR-221) was highly effective in promoting in vitro chondrogenesis of monolayered hMSCs in the absence of the chondrogenic induction factor TGF-β. Here we investigated the feasibility of this approach first in conventional 3D pellet culture and then in an in vivo model. In pellet cultures, we observed that miR-221 silencing was sufficient to drive hMSCs towards chondrogenic differentiation in the absence of TGF-β. In vivo, the potential of miR-221 silenced hMSCs was investigated by first encapsulating the cells in alginate and then by filling a cartilage defect in an osteochondral biopsy. After implanting the biopsy subcutaneously in nude mice, we found that silencing of miR-221 strongly enhanced in vivo cartilage repair compared to the control conditions (untreated hMSCs or alginate-only). Notably, miR-221 silenced hMSCs generated in vivo a cartilaginous tissue with no sign of collagen type X deposition, a marker of undesired hypertrophic maturation. Altogether our data indicate that silencing miR-221 has a pro-chondrogenic role in vivo, opening new possibilities for the use of hMSCs in cartilage tissue engineering. This article is protected by copyright. All rights reserved

    Tokamak cooling systems and power conversion system options

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    DEMO will be a fusion power plant demonstrating the integration into the grid architecture of an electric utility grid. The design of the power conversion chain is of particular importance, as it must adequately account for the specifics of nuclear fusion on the generation side and ensure compatibility with the electric utility grid at all times. One of the special challenges the foreseen pulsed operation, which affects the operation of the entire heat transport chain. This requires a time-dependant analysis of different concept design approaches to ensure proof of reliable operation and efficiency to obtain nuclear licensing. Several architectures of Balance of Plant were conceived and developed during the DEMO Pre-Concept Design Phase in order to suit needs and constraints of the in-vessel systems, with particular regard to the different blanket concepts. At this early design stage, emphasis was given to the achievement of robust solutions for all essential Balance of Plant systems, which have chiefly to ensure feasible and flexible operation modes during the main DEMO operating phases – Pulse, Dwell and ramp-up/down – and to adsorb and compensate for potential fusion power fluctuations during plasma flat-top. Although some criticalities, requiring further design improvements were identified, these preliminary assessments showed that the investigated cooling system architectures have the capability to restore nominal conditions after any of the abovementioned cases and that the overall availability could meet the DEMO top-level requirements. This paper describes the results of the studies on the tokamak coolant and Power Conversion System (PCS) options and critically highlights the aspects that require further work
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