scholarly journals RELAP5 Analyses of ROSA/LSTF Experiments on AM Measures during PWR Vessel Bottom Small-Break LOCAs with Gas Inflow

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Takeshi Takeda
Keyword(s):  
Sensitivity Analyses ◽  
Injection System ◽  
Two Phase ◽  
Gas Accumulation ◽  
Noncondensable Gas ◽  
Pressure Injection ◽  
Total Failure ◽  
Core Cooling ◽  
Vessel Bottom

RELAP5 code posttest analyses were performed on ROSA/LSTF experiments that simulated PWR 0.2% vessel bottom small-break loss-of-coolant accidents with different accident management (AM) measures under assumptions of noncondensable gas inflow and total failure of high-pressure injection system. Depressurization of and auxiliary feedwater (AFW) injection into the secondary-side of both steam generators (SGs) as the AM measures were taken 10 min after a safety injection signal. The primary depressurization rate of 55 K/h caused rather slow primary depressurization being obstructed by the gas accumulation in the SG U-tubes after the completion of accumulator coolant injection. Core temperature excursion thus took place by core boil-off before the actuation of low-pressure injection (LPI) system. The fast primary depressurization by fully opening the relief valves in both SGs with continuous AFW injection led to long-term core cooling by the LPI actuation even under the gas accumulation in the SG U-tubes. The code indicated remaining problems in the predictions of break flow rate during two-phase flow discharge period and primary pressure after the gas inflow. Influences of the primary depressurization rate with continuous AFW injection onto the long-term core cooling were clarified by the sensitivity analyses.

A Comprehensive Thermodynamic Approach to Acoustic Cavitation Simulation in High-Pressure Injection Systems by a Conservative Homogeneous Two-Phase Barotropic Flow Model

2005 ◽  
Vol 128 (2) ◽  
pp. 434-445 ◽  
Author(s):  
Andrea E. Catania ◽  
Alessandro Ferrari ◽  
Michele Manno ◽  
Ezio Spessa
Keyword(s):  
High Pressure ◽  
Wave Propagation ◽  
Flow Model ◽  
Acoustic Cavitation ◽  
Injection System ◽  
Pure Liquid ◽  
Two Phase ◽  
Pressure Injection ◽  
Barotropic Flow ◽  
High Pressure Injection

A general conservative numerical model for the simulation of transmission-line unsteady fluid dynamics has been developed and applied to high-pressure injection systems. A comprehensive thermodynamic approach for modeling acoustic cavitation, i.e., cavitation induced by wave propagation, was proposed on the basis of a conservative homogeneous two-phase barotropic flow model of a pure liquid, its vapor, and a gas, both dissolved and undissolved. A physically consistent sound speed equation was set in a closed analytical form of wide application. For the pure-liquid flow simulation outside the cavitation regions, or in the absence of these, temperature variations due to compressibility effects were taken into account, for the first time in injection system simulation, through a thermodynamic relation derived from the energy equation. Nevertheless, in the cavitating regions, an isothermal flow was retained consistently with negligible macroscopic thermal effects due to vaporization or condensation, because of the tiny amounts of liquid involved. A novel implicit, conservative, one-step, symmetrical, and trapezoidal scheme of second-order accuracy was employed to solve the partial differential equations governing the pipe flow. It can also be enhanced at a high-resolution level. The numerical model was applied to wave propagation and cavitation simulation in a high-pressure injection system of the pump-line-nozzle type for light and medium duty vehicles. The system was relevant to model assessment because, at part loads, it presented cavitating flow conditions that can be considered as severe, at least for a diesel injection system. The predicted time histories of pressure at two pipe locations and of injector needle lift were compared to experimental results, substantiating the validity and robustness of the developed conservative model in simulating acoustic cavitation inception and desinence with great accuracy degree. Cavitation transients and the flow discontinuities induced by them were numerically predicted and analyzed.

Development of Steam Generator Model Using RELAP5 to Simulate Two-Phase Natural Circulation for Pressurized Water Reactor

2014 ◽  
Author(s):  
Shinya Miyata ◽  
Satoru Kamohara ◽  
Wataru Sakuma ◽  
Hiroaki Nishi
Keyword(s):  
Steam Generator ◽  
Natural Circulation ◽  
Injection System ◽  
Pressurized Water Reactor ◽  
Two Phase ◽  
Pressurized Water ◽  
Water Reactor ◽  
Loss Of Coolant ◽  
Mass Inventory ◽  
Core Cooling

In typical pressurized water reactor (PWR), to cope with beyond design basis events such as station black out (SBO) or small break loss of coolant accident with safety injection system failure, injection from accumulator sustains core cooling by compensating for loss of coolant. Core cooling is sustained by single- or two-phase natural circulation or reflux condensation depending on primary coolant mass inventory. Behavior of the natural circulation in PWR has been investigated in the facilities such as Large Scale Test Facility (LSTF) which is a full-height and full-pressure and thermal-hydraulic simulator of typical four-loop PWR. Two steady-state natural circulation tests were conducted in LSTF at both high and low pressure. These two tests were conducted changing the primary mass inventory as a test parameter, while keeping the other parameters such as core power, steam generator (SG) pressure, and steam generator water level as they are. Mitsubishi Heavy Industries (MHI) plans new natural circulation tests to cover wider range of core power and pressure as test-matrix (including the previous LSTF tests) to validate applicability of the model in wider range of core power and pressure conditions including the SBO conditions. In this paper, the previous LSTF natural circulation tests are reviewed and the new test plan will be described. Additionally, MHI also started a feasibility study to improve the steam generator tube and inlet/outlet plenum model using the M-RELAP5 code [4]. Newly developed model gives reasonable agreement with the previous LSTF tests and applies to the new test conditions. The feasibility findings will also be described in this paper.

Direct Vessel Vertical Injection for Advanced Emergency Core Cooling System

2004 ◽  
Author(s):  
Sang H. Yoon ◽  
Kune Y. Suh ◽  
Yong H. Yu
Keyword(s):  
Cooling System ◽  
Injection System ◽  
Test Apparatus ◽  
Two Phase ◽  
The Core ◽  
Vertical Injection ◽  
National University ◽  
Seoul National University ◽  
Core Cooling ◽  
Direct Bypass

A direct vessel vertical injection (DVVI) system, which is an improved variation of the current direct vessel injection (DVI) system for the APR1400 (Advanced Power Reactor 1400 MWe), is being developed by PHILOSOPHIA, Inc. and the Seoul National University in collaboration with the Korea Atomic Energy Research Institute (KAERI). The DVVI aims to sizably enhance penetration of the emergency core coolant (ECC) into the downcomer. This industry-academia-laboratory trilateral project is being carried out at the THETA (Transient Hydrodynamic Engineering Test Apparatus) apparatus. Once the engineering design is verified and validated, the system is slated to be employed in the more advanced reactor D2R2 (Digital R&D Reactor) to cope with loss-of-coolant accidents (LOCAs). While the ECC injection through the DVI system is known to cause multidimensional thermal hydraulic phenomena such as the impingement and breakup in the reactor downcomer, the DVVI injection system can deliver more ECC into the lower plenum and the core because of the increased downward momentum. CFX, which is a multidimensional fluid dynamics code, was used to analyze the flow pattern for the water from the DVVI versus DVI nozzles and the air from the cold legs. Results indicated that the two-phase flow distributions and downward velocities between the DVVI and DVI systems were considerably different and that the ECC penetration path into the core was clearer in the DVVI system. Experiments were performed in the 1:10 scaled-down test apparatus to measure the water-air two-phase direct bypass ratio for the DVVI system, which was less than that for DVI. The direct bypass was visualized and measured. Once the nozzle manufacturing and assembly procedures are engineered, results of this work may well contribute to improving the ECC penetration capability in the advanced reactors like D2R2.

Implicit Numerical Model of a High-Pressure Injection System

1992 ◽  
Vol 114 (3) ◽  
pp. 534-543 ◽  
Author(s):  
A. E. Catania ◽  
C. Dongiovanni ◽  
A. Mittica
Keyword(s):  
High Pressure ◽  
Differential Equations ◽  
Gaussian Elimination ◽  
Injection Pressure ◽  
Injection System ◽  
Algebraic Equations ◽  
Two Phase ◽  
Boundary Shear ◽  
Pressure Injection ◽  
High Pressure Injection

An implicit finite-difference numerical method has been developed and applied to the simulation of unsteady flow phenomena in a high-pressure injection system. A first-order one-step BSBT (backward space, backward time) scheme was used to obtain the difference analogue of the one-dimensional, elemental-volume averaged, partial differential equations governing the pressure-pipe flow. Second and higher-order implicit difference representations were employed for the ordinary differential equations simulating the pump and injector dynamics. The resultant nonlinear algebraic equations were solved by the Newton-Raphson method and a fast modified version of the Gaussian elimination procedure was used to solve the linearized equations. This was an extension of the Thomas solver to a multidiagonal system of algebraic equations. A compact, efficient and stable numerical algorithm was so obtained. The mathematical model takes into account the compressibility of the liquid fuel, the boundary shear, and also includes the simulation of possible cavitation occurrence at one or multiple locations in the injection system. No artificial viscosity has to be added to the solution in the vicinity of discontinuities induced by cavitation in the flow properties. The cavitation simulation is based on a simple mixture model of transient two-phase flow in pipes and can incorporate the effects of gaseous cavitation occurrence. Experimental values of the flow coefficients were used for the pump and injector and, for the latter, the dependence of the discharge coefficients on the needle lift and injection pressure was also taken into account. The model was tested and validated by comparing the numerical results with those of experiments carried out at the Fiat Research Center on a diesel-engine inline injection system, with a jerk-pump and an orifice type nozzle-injector.

Long-term Efficacy and Safety of Brodalumab in Patients With Psoriasis Disease Duration <10 and ≥10 Years: Analysis of Two Phase 3 Studies

2019 ◽  
Vol 3 ◽  
pp. S25
Author(s):  
Benjamin Ehst ◽  
George Han ◽  
Scott Guenthner ◽  
Kimberly Eads ◽  
Abby Jacobson
Keyword(s):  
Disease Duration ◽  
Efficacy And Safety ◽  
Phase 3 ◽  
Two Phase ◽  
Term Efficacy

Abstract not available.

35 Social Contact Mode and 15-Year Episodic Memory Trajectories in Older Adults with and Without Hearing Loss: the Elsa Study

2021 ◽  
Vol 50 (Supplement_1) ◽  
pp. i7-i11
Author(s):  
S Rafnsson ◽  
A Maharani ◽  
G Tampubolon
Keyword(s):  
Older Adults ◽  
Hearing Loss ◽  
Social Network ◽  
Episodic Memory ◽  
Social Interactions ◽  
Social Contact ◽  
Sensitivity Analyses ◽  
Impaired Hearing ◽  
Contact Mode

Abstract Introduction Frequent social contact benefits cognition in later life although evidence is lacking on the potential importance of the modes chosen by older adults for interacting with others in their social network. Method 11,513 participants in the English Longitudinal Study of Ageing (ELSA) provided baseline information on hearing status and social contact mode and frequency of use. Multilevel growth curve models compared episodic memory (immediate and delayed recall) at baseline and long-term in participants who interacted frequently (offline only or offline and online combined), compared to infrequently, with others in their social network. Results Frequent offline (β = 0.29; p &lt; 0.05) and combined offline and online (β = 0.76; p &lt; 0.001) social interactions predicted better episodic memory after adjustment for multiple confounding factors. We observed positive long-term influences of combined offline and online interactions on memory in participants without hearing loss (β = 0.48, p = 0.001) but not of strictly offline interactions (β = 0.00, p = 0.970). In those with impaired hearing, long-term memory was positively influenced by both modes of engagement (offline only: β = 0.93, p &lt; 0.001; combined online and offline: β = 1.47, p &lt; 0.001). Sensitivity analyses confirmed the robustness of these findings. Conclusion Supplementing conventional social interactions with online communication modes may help older adults, especially those living with hearing loss, sustain, and benefit cognitively from, personal relationships.

scholarly journals THU0207 SUSTAINABILITY OF RESPONSE TO UPADACITINIB AS MONOTHERAPY OR IN COMBINATION AMONG PATIENTS WITH RHEUMATOID ARTHRITIS AND PRIOR INADEQUATE RESPONSE TO CONVENTIONAL SYNTHETIC DMARDS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 327.1-328
Author(s):  
A. Kavanaugh ◽  
M. H. Buch ◽  
B. Combe ◽  
L. Bessette ◽  
I. H. Song ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Disease Activity ◽  
Inadequate Response ◽  
Research Support ◽  
Two Phase ◽  
First Occurrence ◽  
Activity Measures ◽  
Disease Activity Measures

Background:The primary treatment goal for patients (pts) with rheumatoid arthritis (RA) is a state of sustained clinical remission (REM) or low disease activity (LDA).1,2Objectives:To assess the long-term sustainability of responses to upadacitinib (UPA), a JAK inhibitor, with or without background csDMARD(s) in pts with RA.Methods:Data are from two phase 3 randomized, controlled trials of UPA in RA pts with roughly similar baseline disease characteristics: SELECT-NEXT enrolled pts with an inadequate response (IR) to csDMARD(s) on background stable csDMARD(s) receiving UPA 15 mg or 30 mg once daily or placebo for 12 weeks (wks); SELECT-MONOTHERAPY enrolled methotrexate (MTX)-IR pts receiving UPA 15 mg or 30 mg monotherapy or blinded MTX for 14 wks. After 12/14 wks, pts could enter a blinded long-term extension and receive UPA 15 mg or 30 mg for up to 5 years. This post hoc analysis evaluated clinical REM (CDAI ≤2.8; SDAI ≤3.3), LDA (CDAI≤10; SDAI≤11), and DAS28(CRP) <2.6/≤3.2 at first occurrence before Wk 84; additionally, these measures were evaluated at 3, 6, and 12 months after the first occurrence for the total number of pts randomized to UPA 15 mg. Sustainability of response was evaluated by Kaplan-Meier only for those pts who achieved REM/LDA and was defined as time to the earliest date of losing response at two consecutive visits or discontinuation of study drug. The predictive ability of time to clinical REM/LDA was assessed using Harrell’s concordance (c)-index (for reference, an index ~ 0.5, indicates no ability to predict; an index of 1 or -1 would be a perfect prediction). The last follow up dates were 22 March, 2018 (SELECT-NEXT) and 25 May, 2019 (SELECT-MONOTHERAPY), when all pts had reached the Wk 84 visit.Results:Through Wk 84, the percent of treated pts achieving CDAI REM/LDA was 43%/79% for those receiving UPA 15 mg with background csDMARD(s) (SELECT-NEXT) and 37%/76% for those receiving UPA 15 mg without background csDMARD(s) (SELECT-MONOTHERAPY). 35%/25% of pts randomized to UPA 15 mg with background csDMARD(s) and 27%/23% of pts randomized to UPA 15 mg without background csDMARD(s) achieved sustained CDAI REM through 6/12 months after the first occurrence. 64%/56% of pts randomized to UPA 15 mg with background csDMARD(s) and 61%/56% of pts randomized to UPA 15 mg without background csDMARD(s) achieved sustained CDAI LDA through 6/12 months after the first occurrence (Figure 1). Time to initial clinical REM/LDA did not appear to be associated with sustained disease control. The c-indices (95%CI) for CDAI REM in the UPA 15 mg with background csDMARD(s) and UPA 15 mg without background csDMARD(s) groups were 0.541 (0.47, 0.62) and 0.568 (0.49, 0.65) and that of LDA were 0.521 (0.46, 0.58) and 0.498 (0.43, 0.56), respectively. Through last follow-up visit, 55% of pts receiving UPA 15 mg with background csDMARD(s) and 62% of pts receiving UPA 15 mg without background csDMARD(s) remained in CDAI REM while 72% and 70% of pts remained in CDAI LDA, respectively (Figure 2). Similar results were observed across other disease activity measures (SDAI REM/LDA and DAS28(CRP) <2.6/≤3.2).Conclusion:More than a quarter and more than a half of pts with RA and prior IR to csDMARD(s) receiving UPA with or without background csDMARD therapy achieved sustained clinical REM and LDA, respectively, across disease activity measures. Sustainability of responses appeared comparable among pts receiving UPA with or without background csDMARDs through up to 84 wks.References:[1]EULAR: Smolen JS, et al. Ann Rheum Dis 2017;76:960–977.[2]ACR: Singh et al. Arthritis & Rheumatology Vol. 68, No. 1, January 2016, pp 1–26.Disclosure of Interests: :Arthur Kavanaugh Grant/research support from: Abbott, Amgen, AstraZeneca, BMS, Celgene Corporation, Centocor-Janssen, Pfizer, Roche, UCB – grant/research support, Maya H Buch Grant/research support from: Pfizer, Roche, and UCB, Consultant of: Pfizer; AbbVie; Eli Lilly; Gilead Sciences, Inc.; Merck-Serono; Sandoz; and Sanofi, Bernard Combe Grant/research support from: Novartis, Pfizer, Roche-Chugai, Consultant of: AbbVie; Gilead Sciences, Inc.; Janssen; Eli Lilly and Company; Pfizer; Roche-Chugai; Sanofi, Speakers bureau: Bristol-Myers Squibb; Gilead Sciences, Inc.; Eli Lilly and Company; Merck Sharp & Dohme; Pfizer; Roche-Chugai; UCB, Louis Bessette Grant/research support from: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, Merck, Novartis, Pfizer, Roche, Sanofi, UCB Pharma, Consultant of: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, Merck, Novartis, Pfizer, Roche, Sanofi, UCB Pharma, Speakers bureau: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, Merck, Novartis, Pfizer, Sanofi, In-Ho Song Shareholder of: AbbVie Inc., Employee of: AbbVie Inc., Yanna Song Shareholder of: AbbVie Inc., Employee of: AbbVie Inc., Jessica Suboticki Shareholder of: AbbVie Inc., Employee of: AbbVie Inc., Peter Nash Grant/research support from: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly and Company, Gilead, Janssen, MSD, Novartis, Pfizer Inc, Roche, Sanofi, UCB, Consultant of: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Gilead, Janssen, MSD, Novartis, Pfizer Inc, Roche, Sanofi, UCB, Speakers bureau: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Gilead, Janssen, MSD, Novartis, Pfizer Inc, Roche, Sanofi, UCB

scholarly journals Long-term exposure to iron and copper in fine particulate air pollution and their combined impact on reactive oxygen species concentration in lung fluid: a population-based cohort study of cardiovascular disease incidence and mortality in Toronto, Canada

2020 ◽  
Author(s):  
Zilong Zhang ◽  
Scott Weichenthal ◽  
Jeffrey C Kwong ◽  
Richard T Burnett ◽  
Marianne Hatzopoulou ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cardiovascular Disease ◽  
Regression Models ◽  
Population Based ◽  
Sensitivity Analyses ◽  
Oxygen Species ◽  
Lung Fluid ◽  
Fine Particulate ◽  
Combined Impact

Abstract Background Exposure to fine particulate (PM2.5) air pollution is associated with increased cardiovascular disease (CVD), but less is known about its specific components, such as metals originating from non-tailpipe emissions. We investigated the associations of long-term exposure to metal components [iron (Fe) and copper (Cu)] in PM2.5 with CVD incidence. Methods We conducted a population-based cohort study in Toronto, Canada. Exposures to Fe and Cu in PM2.5 and their combined impact on the concentration of reactive oxygen species (ROS) in lung fluid were estimated using land use regression models. Incidence of acute myocardial infarction (AMI), congestive heart failure (CHF) and CVD death was ascertained using health administrative datasets. We used mixed-effects Cox regression models to examine the associations between the exposures and health outcomes. A series of sensitivity analyses were conducted, including indirect adjustment for individual-level cardiovascular risk factors (e.g. smoking), and adjustment for PM2.5 and nitrogen dioxide (NO2). Results In single-pollutant models, we found positive associations between the three exposures and all three outcomes, with the strongest associations detected for the estimated ROS. The associations of AMI and CHF were sensitive to indirect adjustment, but remained robust for CVD death in all sensitivity analyses. In multi-pollutant models, the associations of the three exposures generally remained unaltered. Interestingly, adjustment for ROS did not substantially change the associations between PM2.5 and CVD, but attenuated the associations of NO2. Conclusions Long-term exposure to Fe and Cu in PM2.5 and their combined impact on ROS were consistently associated with increased CVD death.

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