Numerical simulation of two-phase flow behavior in Venturi scrubber by interface tracking method

From the viewpoint of protecting a containment vessel of light water reactor and suppressing the diffusion of radioactive materials from a light water reactor, it is important to develop the device which allows a filtered venting of contaminated high pressure gas. In the filtered venting system that used in European reactors, so called Multi Venturi scrubbers System is used to realize filtered venting without any power supply. This system is able to define to be composed of Venturi scrubbers (VS) and a bubble column. In the VS, scrubbing of contaminated gas is promoted by both gas releases through the submerged VS and gas-liquid contact with splay flow formed by liquid suctioned through a hole provided by the pressure difference between inner and outer regions of a throat part of the VS. However, the scrubbing mechanism of the self-priming VS including effects of gas mass flow rate and shape of the VS are understood insufficiently in the previous studies. Therefore, we started numerical and experimental study to understand the detailed two-phase flow behavior in the VS. In this paper, to understand the VS operation characteristics for the filtered venting, we performed numerical simulations of two-phase flow behavior in the VS. In the first step of this study, we perform numerical simulations of supersonic flow by the TPFIT to validate the applicability of the TPFIT for high velocity flow like flow in the VS. In the second step, numerical simulation of two-phase flow behavior in the VS including self-priming phenomena. As the results, dispersed flow in the VS was reproduced in the numerical simulation, as same as the visualization experiments

Interaction between caesium iodide particles and gaseous boric acid in a flowing system through a thermal gradient tube (1030 K–450 K) and analysis with ASTEC/SOPHAEROS

International audienceThe present work aimed at studying the interaction between caesium iodide particles and gaseous boric acidthrough a Thermal Gradient Tube (TGT) from 1023 K to 453 K under Ar/H2O. Particles size range of transportedparticles was measured by ELPI and the fraction of gaseous compounds by ICP-MS and UV–visible spectroscopy.Reaction between the two compounds was deduced by measuring a significant fraction of gaseous iodine at theoutlet of the facility, representing more than 80% of the total iodine sampled at the outlet. The reaction rate wasshown to be lower when the flow rate inside the facility was increased. Analysis with SOPHAEROS module ofASTEC code was performed. The ASTEC fission products models allowed performing the evaluation of theexperimentally observed results for the analysis of the transport of pure compounds. However, the heterogeneousinteraction between the caesium iodide particles and the gaseous boric acid was not reproduced, as the modelsare not taken into account in the version v2.1_1_6 of the ASTEC/SOPHAEROS module. The next step would be toidentify the mechanism of the reaction by comparing the results with other studies and to determine the reactionrates. Then, a first development in SOPHAEROS would be to implement such phenomena

For Vol.70, No.5 pp405-408 A Multicenter, Prospective, Randomized Controlled Trial Evaluating the Efficacy of Rectal Diclofenac and Sublingual Nitrate as a Combined Prophylactic Treatment for Post-ERCP Pancreatitis

In the article by Tomoda T et al. entitled “A Multicenter, Prospective, Randomized Controlled Trial Evaluating the Efficacy of Rectal Diclofenac and Sublingual Nitroglycerin as a Combined Prophylactic Treatment for Post-ERCP Pancreatitis”, which appeared in the October 2016 issue, Vol. 70, No. 5, pp405-408, the word “nitroglycerin” should be corrected to “nitrate” throughout the manuscript

Distinct Clinic-Pathological Features of Early Differentiated-Type Gastric Cancers after Helicobacter pylori

Background. Gastric cancer is discovered even after successful eradication of H. pylori. We investigated clinic pathological features of early gastric cancers after H. pylori eradication. Methods. 51 early gastric cancers (EGCs) from 44 patients diagnosed after successful H. pylori eradication were included as eradication group. The clinic-pathological features were compared with that of 131 EGCs from 120 patients who did not have a history of H. pylori eradication (control group). Results. Compared with control group, clinic-pathological features of eradication group were characterized as depressed (p<0.0001), reddish (p=0.0001), and smaller (p=0.0095) lesions, which was also confirmed in the comparison of six metachronous lesions diagnosed after initial ESD and subsequent successful H. pylori eradication. Prevalence of both SM2 (submucosal invasion greater than 500 μm) and unexpected SM2 cases tended to be higher in eradication group (p=0.077, 0.0867, resp.). Prevalence of inconclusive diagnosis of gastric cancer during pretreatment biopsy was also higher in the same group (26.0% versus 1.6%, p<0.0001). Conclusions. Informative clinic pathological features of EGC after H. pylori eradication are depressed, reddish appearances, which should be treated as a caution because histological diagnosis of cancerous tissue is sometimes difficult by endoscopic biopsy

A Multicenter, Prospective, Randomized Controlled Trial Evaluating the Efficacy of Rectal Diclofenac and Sublingual Nitroglycerin as a Combined Prophylactic Treatment for Post-ERCP Pancreatitis

Acute pancreatitis is the major complication of endoscopic retrograde cholangiopancreatography (ERCP). A preliminary research suggested that the administration of nonsteroidal anti-inflammatory drugs (NSAIDs) with nitroglycerin might reduce the incidence of post-ERCP pancreatitis (PEP) more effectively than NSAIDs alone. We conduct a two-arm, multicenter, prospective, randomized, superiority trial to evaluate the additional effect of nitroglycerin for prevention of PEP. A total of 900 patients randomly receive 50 mg diclofenac suppository either alone or with 5 mg isosorbide dinitrate sublingual tablet. The primary endpoint is the occurrence of PEP. This study will clarify whether NSAIDs plus nitroglycerin can prevent PEP

Diagnosing Pancreatic Tumors Using Contrast-enhanced Harmonic Endoscopic Ultrasonography with Sonazoid

Contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) with contrast agent enabled us to assess the hemodynamics closely, despite limited data in pancreatic tumors. We have initiated a prospective, single arm, and non-randomized study to clarify the accuracy and safety of CH-EUS with Sonazoid and time-intensity curve (TIC) analysis for diagnosing benign or malignant pancreatic tumors. A total of 200 patients will undergo CH-EUS and TIC analysis. Receiver operating characteristic (ROC) analysis will be used to determine the optimal parameter cutoff values for TIC analysis. This will clarify whether CH-EUS and TIC can further improve the diagnosis of pancreatic tumors over conventional EUS

Efficacy and Safety of Endoscopic Ultrasound-guided Ethanol Ablation Therapy for Pancreatic Neuroendocrine Tumors

Recently, endoscopic ultrasonography (EUS)-guided ethanol ablation for small pancreatic neuroendocrine tumors (p-NETs) has been reported. However, the efficacy and safety of the technique remain unclear. We have launched a prospective pilot study of EUS-guided ethanol ablation for p-NETs. The major eligibility criteria are the presence of a pathologically diagnosed grade (G) 1 or G2 p-NET, a tumor size of 2cm, and being a poor candidate for surgery. A total of 5 patients will be treated. The primary endpoint will be the complete ablation rate at 1 month after treatment

A Prospective Randomized Controlled Study Comparing EUS Sonopsy CY(R) and 22-gauge Biopsy Needles for Endoscopic Ultrasound-guided Fine-Needle Aspiration of Solid Pancreatic Mass Lesions

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is a standard procedure for precise histological diagnosis of pancreas tumors, but it is sometimes difficult to obtain adequate specimens. EUS Sonopsy CY® is a newly designed needle with original features. This randomized study will compare the tissue collection rate of EUS Sonopsy CY® to that of a conventional needle in EUS-FNA. The major eligibility criteria are as follows: Patients with a pancreatic mass referred for EUSFNA; age &ge;20 years, and performance status＜4. The primary outcome is the tissue collection rate. This study will elucidate the efficacy of EUS Sonopsy CY®

Dynamic computed tomography is useful for prediction of pathological grade in pancreatic neuroendocrine neoplasm

BACKGROUND AND AIM: Pathological grading is important in defining the therapeutic strategy in pancreatic neuroendocrine neoplasm (PNEN) but is difficult for unresectable cases. Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) is useful in the diagnosis of PNEN, but its usefulness for pathological grading is not well established. No studies have examined the diagnostic ability of dynamic computed tomography (CT) for pathological grading of PNEN. We investigated the usefulness of EUS-FNA and dynamic CT in the diagnosis and pathological grading of PNEN. METHODS: In this retrospective study, 39 PNEN patients finally diagnosed via EUS-FNA and/or surgical resection underwent dynamic CT. Pathological samples were diagnosed based on WHO2010; staging was based on the European Neuroendocrine Tumor Society classification. The proportion of the quantification value in the tumor to the pancreatic parenchyma in arterial phase was defined as the CT ratio. Immunohistochemical staining with CD31 was performed to evaluate microvessel density (MVD). We evaluated the relationship between pathological grade, CT ratio, and MVD. RESULTS: By using EUS-FNA, 35 of 39 (90%) cases were diagnosed as PNEN. As for pathological grade, 15 of 35 (43%) cases could be identified correctly. CT ratio could predict pathological Grade 3 disease. The sensitivity, specificity, and diagnostic accuracy were 100%, 94%, and 95%. MVD was significantly correlated with CT ratio (r = 0.83, P < 0.0001) and pathological grade (P = 0.0074). CONCLUSIONS: Computed tomography ratio has a relationship with pathological grade in PNEN, which would help decide therapeutic strategy in unresectable cases and cases in which pathological grading is difficult