The Effect f Waste Package and Engineered Barrier System Design:Options on Long-Term Waste Package Degradation Characteristics

1999 ◽  
Vol 556 ◽  
Author(s):  
J. H. Lee ◽  
K. G. Mon ◽  
B. E. Bullard ◽  
D. E. Longsine
Keyword(s):  
Current Model ◽  
Localized Corrosion ◽  
Sensitivity Analyses ◽  
Exposure Condition ◽  
Reference Case ◽  
Waste Package ◽  
Engineered Barrier ◽  
Design Options ◽  
The Impact

AbstractSensitivity analyses were conducted to evaluate the impact of a number of waste package and engineered barrier system (EBS) design options on long-term waste package degradation in the potential repository at Yucca Mountain, Nevada. The evaluations were performed by analyzing the waste package degradation in terms of the first breach and first pit-breach profiles with time. Results for each design option were assessed by comparing to results for the reference-case design. An important finding from the analyses is that the waste package lifetime could be extended substantially by limiting and delaying the contact of dripping water with the Alloy 22 corrosion resistant material (CRM) barrier. In the current model, this would keep the CRM barrier outside the conditions that makes the alloy susceptible to localized corrosion. Uncertainty in waste package degradation analysis would be reduced by improved understanding and characterization of the processes that create the local exposure condition on waste package.

Stochastic Modeling of Long-Term Waste Package Degradation Incorporating Expert Elicitation on Corrosion Processes

1999 ◽  
Vol 556 ◽  
Author(s):  
J. H. Lee ◽  
K. G. Mori ◽  
D. E. Longsine ◽  
B. E. Bullard
Keyword(s):  
Primary Component ◽  
Expert Elicitation ◽  
Localized Corrosion ◽  
General Corrosion ◽  
Reference Case ◽  
Waste Package ◽  
Waste Container ◽  
Reference Design ◽  
High Level

AbstractThe Viability Assessment (VA) of the potential repository for high-level nuclear waste at Yucca Mountain, Nevada was completed [1]. In the VA design concept, a two-layer waste container provides the primary component of the engineered barrier system (EBS). The VA reference design specifies a 100-mm thick carbon steel as the outer barrier and a 20-mm thick Alloy 22 as the inner barrier. A stochastic simulation model was developed to analyze long-term performance of the waste package in the potential repository. The model was developed by incorporating the latest corrosion data and models for the candidate waste package materials and the information developed from the Waste Package Degradation Expert Elicitation (WPDEE) [2].The reference case results showed that only a small fraction of waste packages fail by localized corrosion (i.e., pit penetrations). The analysis also indicated the degradation mode that is most important to long-term waste package degradation is general corrosion (or passive dissolution) of the inner barrier under dripping conditions. However, the general corrosion rates for dripping conditions used in the analysis have a range over three to five orders of magnitude. This is due mainly to a lack of information on local chemical and electrochemical conditions on the inner barrier after the outer barrier breach. This paper discusses further the areas and issues that need improvement to reduce uncertainty in the waste package degradation analysis. It also discusses additional waste package degradation modes and associated processes that need to be included in the future analysis for the potential repository to enhance the confidence of the analysis.

Evaluation of The Long-Term Stability of Passive Corrosion On The Drip Shield and Waste Package Under Yucca Mountain Conditions

2002 ◽  
Vol 713 ◽  
Author(s):  
D.W. Shoesmith
Keyword(s):  
Environmental Conditions ◽  
Yucca Mountain ◽  
Localized Corrosion ◽  
Waste Package ◽  
Long Term Stability ◽  
Alloy 22 ◽  
Aqueous Environments ◽  
Engineered Barriers ◽  
Titanium Grade

ABSTRACTPossible long term corrosion scenarios for the engineered barriers proposed for the Yucca Mountain (Nevada, USA) repository are reviewed.Introduction:The materials proposed for the engineered barriers in the Yucca Mountain repository (Nevada, USA), Alloy-22 for the waste packages (WP) and titanium Grade-7 (Ti-7) for the drip shield (DS), appear unlikely to suffer localized corrosion (LC) and have very low passive corrosion (PC) rates (1–3). Since environmental conditions will become more benign as temperatures decline and aqueous environments become more dilute (4), this leads to the prediction of exceedingly long waste package lifetimes. In this review, possible corrosion scenarios are discussed in the context of the anticipated evolution in the repository environment.

scholarly journals The Proposed Yucca Mountain Repository from a Corrosion Perspective

2006 ◽  
Vol 932 ◽  
Author(s):  
Joe H. Payer
Keyword(s):  
Corrosion Resistance ◽  
Nuclear Waste ◽  
Yucca Mountain ◽  
Department Of Energy ◽  
Process Models ◽  
Localized Corrosion ◽  
Waste Package ◽  
Advanced Technologies ◽  
The U.S

ABSTRACTIn this paper, the proposed Yucca Mountain Repository is viewed from a corrosion perspective. A major component of the long-term strategy for safe disposal of nuclear waste at the Yucca Mountain Repository is first to completely isolate the radionuclides in the waste packages for long times and to greatly retard the egress and transport of radionuclides from penetrated packages. Therefore, long-lived waste packages are important. The corrosion resistance of the waste package outer canister is reviewed, and a framework for the analysis of localized corrosion processes is presented. An overview is presented of the Materials Performance targeted thrust of the U.S. Department of Energy/Office of Civilian Radioactive Waste Management's Office of Science and Technology and International. The thrust program strives for increased scientific understanding, enhanced process models and advanced technologies for corrosion control.

scholarly journals Long-Term Blood Pressure Variability and Risk of Cardiovascular Disease Events Among Community-Dwelling Elderly

Hypertension ◽  
2020 ◽  
Vol 76 (6) ◽  
pp. 1945-1952
Author(s):  
Michael E. Ernst ◽  
Enayet K. Chowdhury ◽  
Lawrence J. Beilin ◽  
Karen L. Margolis ◽  
Mark R. Nelson ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiovascular Disease ◽  
Older Adults ◽  
Blood Pressure Variability ◽  
Community Dwelling ◽  
Sensitivity Analyses ◽  
Link Type ◽  
Increased Risk ◽  
The Impact

High office blood pressure variability (OBPV) in midlife increases the risk of cardiovascular disease (CVD), but the impact of OBPV in older adults without previous CVD is unknown. We conducted a post hoc analysis of ASPREE trial (Aspirin in Reducing Events in the Elderly) participants aged 70-years and older (65 for US minorities) without history of CVD events at baseline, to examine risk of incident CVD associated with long-term, visit-to-visit OBPV. CVD was a prespecified, adjudicated secondary end point in ASPREE. We estimated OBPV using within-individual SD of mean systolic BP from baseline and first 2 annual visits. Cox proportional hazards regression was used to calculate hazard ratios (HR) and 95% CI for associations with CVD events. In 16 475 participants who survived to year 2 without events, those in the highest tertile of OBPV had increased risk of CVD events after adjustment for multiple covariates, when compared with participants in the lowest tertile (HR, 1.36 [95% CI, 1.08–1.70]; P =0.01). Similar increased risk was observed for ischemic stroke (HR, 1.56 [95% CI, 1.04–2.33]; P =0.03), heart failure hospitalization, or death (HR, 1.73 [95% CI, 1.07–2.79]; P =0.02), and all-cause mortality (HR, 1.27 [95% CI, 1.04–1.54]; P =0.02). Findings were consistent when stratifying participants by use of antihypertensive drugs, while sensitivity analyses suggested the increased risk was especially for individuals whose BP was uncontrolled during the OBPV estimation period. Our findings support increased OBPV as a risk factor for CVD events in healthy older adults with, or without hypertension, who have not had such events previously. Registration— URL: https://www.clinicaltrials.gov ; Unique identifiers: NCT01038583; URL: https://www.isrctn.com ; Unique identifiers: ISRCTN83772183.

scholarly journals Constraining Roche-Lobe Overflow Models Using the Hot-Subdwarf Wide Binary Population

2017 ◽  
Vol 26 (1) ◽  
pp. 275-279
Author(s):  
Joris Vos ◽  
Maja Vučković
Keyword(s):  
Current Model ◽  
Interaction Model ◽  
Theoretical Models ◽  
Roche Lobe ◽  
Binary Interaction ◽  
Long Term Study ◽  
Gravitational Pull ◽  
Red Giant ◽  
The Impact

AbstractOne of the important issues regarding the final evolution of stars is the impact of binarity. A rich zoo of peculiar, evolved objects are born from the interaction between the loosely bound envelope of a giant, and the gravitational pull of a companion. However, binary interactions are not understood from first principles, and the theoretical models are subject to many assumptions. It is currently agreed upon that hot subdwarf stars can only be formed through binary interaction, either through common envelope ejection or stable Roche-lobe overflow (RLOF) near the tip of the red giant branch (RGB). These systems are therefore an ideal testing ground for binary interaction models. With our long term study of wide hot subdwarf (sdB) binaries we aim to improve our current understanding of stable RLOF on the RGB by comparing the results of binary population synthesis studies with the observed population. In this article we describe the current model and possible improvements, and which observables can be used to test different parts of the interaction model.

Progress in Waste Package and Engineered Barrier System Performance Assessment and Design

1992 ◽  
Vol 294 ◽  
Author(s):  
Abraham Van LUIK ◽  
David Stahl ◽  
Diane Harrison
Keyword(s):  
Environmental Impact ◽  
Performance Assessment ◽  
System Performance ◽  
Site Suitability ◽  
Waste Package ◽  
Waste Repository ◽  
Engineered Barrier ◽  
High Level ◽  
The U.S

ABSTRACTAs part of the U.S. Department of Energy's evaluation of site suitability for a potential high-level radioactive waste repository, long-term interactions between the engineered barrier system and the site must be determined. This requires a waste-package/engineered-system design, a description of the environment around the emplacement zone, and models that simulate operative processes describing these engineered/natural system interactions. Candidate designs are being evaluated, including a more robust, multi-barrier waste package, and a drift emplacement mode. Tools for evaluating designs and emplacement mode are the currently available waste-package/engineered-system performance assessment codes developed for the project. For assessments that support site suitability, environmental impact, or licensing decisions, more capable codes are needed. Code capability requirements are being written, and existing codes are to be evaluated against those requirements. Recommendations are being made to focus waste-package/engineered-system code-development.

Impact of direct-acting antiviral agents-induced SVR on the long-term burden of hepatocellular carcinoma in chronic hepatitis C cirrhosis.

2017 ◽  
Vol 35 (4_suppl) ◽  
pp. 230-230
Author(s):  
Prowpanga Udompap ◽  
Ajitha Mannalithara ◽  
Donghee Kim ◽  
W. Ray Kim
Keyword(s):  
Hepatocellular Carcinoma ◽  
Hepatitis C ◽  
Antiviral Agents ◽  
Sensitivity Analyses ◽  
Old Patients ◽  
Direct Acting Antiviral ◽  
Direct Acting ◽  
The Impact ◽  
Direct Acting Antiviral Agents

230 Background: Sustained virological response (SVR) has been associated with decreased morbidity and mortality from hepatitis C virus (HCV) infection. Data are sparse, however, about the long-term benefits of direct-acting antiviral agents (DAAs) in terms of risk reduction for hepatocellular carcinoma (HCC). We estimate the impact of SVR on the HCC incidence in the DAA era when SVR is achieved nearly universally even in patients with advanced fibrosis and cirrhosis. Methods: We constructed a Markovian model of 50-year-old patients with compensated HCV cirrhosis (n=1,000) to model the incidence of HCC over 20-years of follow-up. We compared 2 cohorts: 1) SVR following DAA therapy and 2) no SVR (natural history). In the latter, HCC would develop at an annual rate of 4.2% and patients would die as a result of end stage liver disease (ESLD) according to their MELD (=6 at baseline). In the former, MELD score would not increase, the HCC risk would decrease and, in some patients, cirrhosis would regress. Results: The table summarizes the 20-year outcome in the two cohorts. In the cohort without SVR, HCC would occur in 33% and 63% would die of ESLD. In the SVR cohort, the proportion of HCC would increase to 37% as the number of subjects at HCC risk would increase, as a result of a dramatic reduction in deaths from ESLD. In the univariate sensitivity analyses, the cumulative HCC incidence was mainly influenced by the rate at which the risk of HCC is decreased after SVR, followed by the change in cirrhosis regression rate. Conclusions: Although HCC risk would decrease after SVR in a given individual patient with cirrhosis, on the population level, highly effective DAA therapy may lead to a paradoxical increase in the burden of HCC. These data underscore the important of (1) HCC surveillance in patients with cirrhosis even after SVR and (2) DAA intervention before cirrhosis develops. [Table: see text]

5α-reductase inhibitors and the risk of grade reclassification for men with long-term follow-up on active surveillance for prostate cancer.

2016 ◽  
Vol 34 (2_suppl) ◽  
pp. 92-92
Author(s):  
Antonio Finelli ◽  
Narhari Timilshina ◽  
Maria Komisarenko ◽  
Robert Sowerby ◽  
Robert James Hamilton ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Active Surveillance ◽  
Cox Proportional Hazards ◽  
Sensitivity Analyses ◽  
Original Cohort ◽  
Reductase Inhibitors ◽  
Increased Risk ◽  
The Impact

92 Background: The role of 5α-reductase inhibitors (5-ARIs) in prostatic diseases remains controversial because of an FDA black box label. We have previously published on the impact of 5-ARIs in men managed with active surveillance (AS), demonstrating their protective effect against progression. However, the long-term safety of 5-ARIs in the setting of AS has never been described, thus we sought to assess this. Methods: This is a single-institution, prospectively maintained, retrospective cohort study comparing men taking a 5-ARI versus no 5-ARI while on AS for PCa. Pathologic progression was evaluated and defined as Gleason score > 6, maximum core involvement > 50%, or more than 3 cores positive on a follow-up prostate biopsy. Time dependent covariate analysis to account for time on AS but not on 5-ARI was conducted to diminish the likelihood of overestimating the benefit. To account for differences in prostate volume at baseline between 5-ARI and non-5-ARI groups sensitivity analyses were performed, restricting men in the non-5-ARI group to those with larger glands (volume > 40 ml). Kaplan-Meier analyses were conducted along with multivariable Cox proportional hazard regression modeling for predictors of pathologic progression. Results: The original cohort of 288 men on AS were analyzed. The median follow-up was 61.2 months (IQR: 29.8-95.24) with 124 men (43%) experiencing pathologic progression and 119 men (41.3%) abandoning AS. Men taking a 5-ARI experienced a lower rate of pathologic progression (24.3% vs 49.1%; p < 0.001) and were less likely to abandon AS (25.7% vs 46.3%; p = 0.002). On multivariable Cox proportional hazards analysis, lack of 5-ARI use was most strongly associated with pathologic progression (HR: 2.56; 95% confidence interval, 1.32-5.02). Sensitivity analyses done to account for gland size demonstrated that lack of 5-ARI use was still predictive of progression (HR: 2.76; CI, 1.45–5.25; p = 0.002). Importantly, 5-ARI use was not associated with increased risk of high-grade prostate cancer. Conclusions: 5-ARIs were associated with a significantly lower rate of pathologic progression and abandonment of AS in men with median follow-up of 5 years.

scholarly journals Long-term effects of compulsory schooling on physical, mental and cognitive ageing: a natural experiment

2019 ◽  
Vol 73 (4) ◽  
pp. 370-376 ◽  
Author(s):  
Emilie Courtin ◽  
Vahe Nafilyan ◽  
Maria Glymour ◽  
Marcel Goldberg ◽  
Claudine Berr ◽  
...  
Keyword(s):  
Depressive Symptoms ◽  
Physical Functioning ◽  
Natural Experiment ◽  
Depression Scale ◽  
Epidemiological Studies ◽  
Sensitivity Analyses ◽  
Long Term Effects ◽  
Compulsory Schooling ◽  
The Impact

BackgroundLonger schooling is associated with better physical, mental and cognitive functioning, but there is controversy as to whether these associations are causal. We examine the long-term health impact of a policy that increased compulsory schooling by 2 years in France for cohorts born on or after January 1953, offering a natural experiment.MethodsData came from Constances, a randomly selected cohort of the French population assessed for cognition, depressive symptoms and physical functioning at ages 45 and older (n=18 929). We use a Regression Discontinuity Design to estimate the impact of increased schooling duration on health. Cognition was measured based on five validated neuropsychological tests and combined into an overall score. The Center for Epidemiological Studies Depression scale was used to assess depressive symptoms levels. Physical functioning was included as finger tapping, hand grip strength and walking speed.ResultsThe reform increased average schooling, particularly among participants from disadvantaged families. Estimates suggest that for men, this reform improved cognitive scores (β=0.15, 95% CI 0.02 to 0.27), but had no impact on physical functioning. Among women, the reform did not increase cognitive scores or physical functioning but led to higher levels of depressive symptoms (β=1.52, 95% CI 0.32 to 2.72). Results were robust to a range of sensitivity analyses.ConclusionThese findings highlight the need to carefully consider the potential limits of policies that increase the length of compulsory schooling as strategies to improve population health.

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