Epistemic and Aleatory Uncertainty in Recommended, Generic Rock Kd Values used in Performance Assessment Studies

2006 ◽  
Vol 932 ◽  
Author(s):  
James Crawford ◽  
Ivars Neretnieks ◽  
Luis Moreno
Keyword(s):  
Performance Assessment ◽  
Laboratory Data ◽  
Scientific Basis ◽  
Performance Assessments ◽  
Aleatory Uncertainty ◽  
Transport Modelling ◽  
Natural Systems ◽  
Rock Types ◽  
Kd Values ◽  
Experimental Laboratory

ABSTRACTOver the past decade or so there has been an explosion in the number of sorption modelling approaches and applications of sorption modelling for understanding and predicting solute transport in natural systems. The most widely used and simplest of all models, however, is that employing a constant distribution coefficient (Kd) relating the sorbed concentration of a solute on a mineral surface and its aqueous concentration.There are a number of reasons why a constant partitioning coefficient is attractive to environmental modellers for predicting radionuclide retardation, and in spite of all the shortcomings and pitfalls associated with such an approach, it remains the leitmotif of most performance assessment transport modelling.This paper examines the scientific basis underpinning the Kd-approach and its broad defensibility in a performance assessment framework. It also examines sources of epistemic and aleatory uncertainty that undermine confidence in Kd-values reported in the open literature. The paper focuses particularly upon the use of so-called “generic” data for generalised rock types that may not necessarily capture the full material property characteristics of site-specific materials.From the examination of recent literature data, it appears that there are still a number of outstanding issues concerning interpretation of experimental laboratory data that need to be considered in greater detail before concluding that the recommended values used in performance assessments are indeed conservative.

scholarly journals SAPHYR: Swiss Atlas of Physical Properties of Rocks: the continental crust in a database

2021 ◽  
Vol 114 (1) ◽  
Author(s):  
Alba Zappone ◽  
Eduard Kissling
Keyword(s):  
Physical Properties ◽  
Laboratory Data ◽  
Rock Physics ◽  
Resource Planning ◽  
Data Representation ◽  
Common People ◽  
Rock Types ◽  
Gis Tools ◽  
Porosity And Permeability ◽  
Thermal And Electrical Properties

AbstractThe Swiss Atlas of Physical Properties of Rocks (SAPHYR) project aims at centralize, uniform, and digitize dispersed and often hardly accessible laboratory data on physical properties of rocks from Switzerland and surrounding regions. The goal of SAPHYR is to make the quality-controlled and homogenized data digitally accessible to an open public, including industrial, engineering, land and resource planning companies as well as governmental and academic institutions, or simply common people interested in rock physics. The physical properties, derived from pre-existing literature or newly measured, are density, porosity and permeability as well as seismic, magnetic, thermal and electrical properties. The data were collected on samples either from outcrops or from tunnels and boreholes. At present, data from literature have been collected extensively for density, porosity, seismic and thermal properties. In the past years, effort has been placed especially on collecting samples and measuring the physical properties of rock types that were poorly documented in literature. A workflow for quality control on reliability and completeness of the data was established. We made the attempt to quantify the variability and the uncertainty of the data. The database has been recently transferred to the Federal Office of Topography swisstopo with the aim to develop the necessary tools to query the database and open it to the public. Laboratory measurements are continuously collected, therefore the database is ongoing and in continuous development. The spatial distribution of the physical properties can be visualized as maps using simple GIS tools. Here the distribution of bulk density and velocity at room conditions are presented as examples of data representation; the methodology to produce these maps is described in detail. Moreover we also present an exemplification of the use of specific datasets, for which pressure and temperatures derivatives are available, to develop crustal models.

Performance Assessments of Geologic Repositories for High-Level Nuclear Waste: Are They Necessary or Sufficient?

2004 ◽  
Vol 824 ◽  
Author(s):  
Rodney C. Ewing
Keyword(s):  
Performance Assessment ◽  
Nuclear Waste ◽  
System Analysis ◽  
Regulatory Compliance ◽  
Performance Assessments ◽  
Data Uncertainty ◽  
Emergent Properties ◽  
Total System ◽  
High Level Nuclear Waste ◽  
High Level

AbstractPerformance assessments of geologic repositories for high-level nuclear waste will be used to determine regulatory compliance. The determination, that with a “reasonable expectation” regulatory limits are met, is based on the presumption that all of the relevant physical, chemical and biological processes have been modeled with enough accuracy to insure that a confident judgment of safety may be made. For the geologic disposal of high-level nuclear waste, this generally means that models must be capable of calculating radiation exposures to a specified population at distances of tens of kilometers for periods of tens to hundreds of thousands of years. A total system performance assessment will consist of a series of cascading models that are meant in toto to capture repository performance. There are numerous sources of uncertainty in these models: scenario uncertainty, conceptual model uncertainty and data uncertainty. These uncertainties will propagate through the analysis, and the uncertainty in the total system analysis must necessarily increase with time. For the highly-coupled, non-linear systems that are characteristic of many of the physical and chemical processes, one may anticipate emergent properties that cannot, in fact, be predicted. For all of these reasons, a performance assessment is not in and of itself a sufficient basis for determining the safety of a repository, but it remains a necessary part of the effort to develop a substantive understanding of a repository site.

Assessed by Anonymous

2021 ◽  
pp. 132-151
Author(s):  
Thomas Huston
Keyword(s):  
Data Analysis ◽  
Teacher Training ◽  
Performance Assessment ◽  
Student Teachers ◽  
Teacher Educators ◽  
Teacher Performance ◽  
Performance Assessments ◽  
Teacher Performance Assessment ◽  
Scholarly Discourse ◽  
Thematic Data

This study sought to contribute to the scholarly discourse of understanding how pre-service student teachers experienced evaluation via teacher performance assessments (TPAs). More specifically, this study sought to explore the experiences that pre-service teachers underwent to complete the Educative Teacher Performance Assessment (edTPA). Through extensive interviews and thematic data analysis, this research discerned what the informants' experiences were. Although informants experienced many benefits while completing their portfolios, three primary areas of struggle emerged from the data. First, informants struggled with interpreting and navigating the edTPA assessment handbook. Second, informants had problems adapting edTPA requirements to their teaching. Third, informants experienced problems with their concept of audience. As a result, the findings reported in this study have numerous implications that would prove beneficial to teacher educators, institutions of teacher training, policymakers, designers of assessments, and future and current educators.

Summary: Panel Discussion on the Role of Performance Assessment for Radioactive Waste Management

1996 ◽  
Vol 465 ◽  
Author(s):  
I. R. Triay ◽  
M. J. Apted
Keyword(s):  
Radioactive Waste ◽  
Waste Management ◽  
Performance Assessment ◽  
Nuclear Waste ◽  
Panel Discussion ◽  
Scientific Basis ◽  
Nuclear Waste Management ◽  
Radioactive Waste Management

The role of performance assessment was discussed by a group of panelists and the participants of the 20th MRS symposium on the “Scientific Basis for Nuclear Waste Management.” Panel members were Professor Thomas Pigford, Dr. Alan Cooper, and Dr. Patrik Sellin; Dr. Michael J. Apted served as moderator. For discussion purposes, “performance assessment” (PA) was defined as the analysis of the release of radionuclides from a repository system of barriers to the accessible environment.

scholarly journals Determining calcium carbonate neutralization kinetics from experimental laboratory data

2012 ◽  
Vol 50 (9) ◽  
pp. 2492-2511 ◽  
Author(s):  
Lorenzo Fusi ◽  
Alessandro Monti ◽  
Mario Primicerio
Keyword(s):  
Calcium Carbonate ◽  
Laboratory Data ◽  
Experimental Laboratory

scholarly journals Addressing evolutionary questions with synthetic biology

2021 ◽  
Author(s):  
Florian Baier ◽  
Yolanda Schaerli
Keyword(s):  
Synthetic Biology ◽  
Regulatory Networks ◽  
Biological Behavior ◽  
Natural Systems ◽  
Experimental Systems ◽  
Engineering Discipline ◽  
Regulatory Circuits ◽  
Evolutionary Advantage ◽  
Experimental Laboratory ◽  
Quantitative Manner

Synthetic biology emerged as an engineering discipline to design and construct artificial biological systems. Synthetic biological designs aim to achieve specific biological behavior, which can be exploited for biotechnological, medical and industrial purposes. In addition, mimicking natural systems using well-characterized biological parts also provides powerful experimental systems to study evolution at the molecular and systems level. A strength of synthetic biology is to go beyond nature’s toolkit, to test alternative versions and to study a particular biological system and its phenotype in isolation and in a quantitative manner. Here, we review recent work that implemented synthetic systems, ranging from simple regulatory circuits, rewired cellular networks to artificial genomes and viruses, to study fundamental evolutionary concepts. In particular, engineering, perturbing or subjecting these synthetic systems to experimental laboratory evolution provides a mechanistic understanding on important evolutionary questions, such as: Why did particular regulatory networks topologies evolve and not others? What happens if we rewire regulatory networks? Could an expanded genetic code provide an evolutionary advantage? How important is the structure of genome and number of chromosomes? Although the field of evolutionary synthetic biology is still in its teens, further advances in synthetic biology provide exciting technologies and novel systems that promise to yield fundamental insights into evolutionary principles in the near future.

scholarly journals Making performance assessments part of accountability

2018 ◽  
Vol 26 ◽  
pp. 15
Author(s):  
Billy Haun
Keyword(s):  
Performance Assessment ◽  
Performance Assessments ◽  
College And Career

The purpose of this commentary is to describe recent efforts in Virginia to develop and use performance assessments, including the challenges that emerged during this process and key considerations for states that integrate performance assessment into their systems. Performance assessments can play an important role in preparing students for success and college and career, as described in Virginia’s Profile of a Virginia Graduate.

Estimates of Mean Consequences and Confidence Bounds on the Mean Associated With Low-Probability Seismic Events in Total System Performance Assessments

2007 ◽  
Author(s):  
Osvaldo Pensado ◽  
James Mancillas
Keyword(s):  
Performance Assessment ◽  
System Performance ◽  
Performance Assessments ◽  
Assessment Model ◽  
Nuclear Waste Repository ◽  
Seismic Events ◽  
Total System ◽  
Confidence Bounds ◽  
The Mean ◽  
Low Probability

An approach is described to estimate mean consequences and confidence bounds on the mean of seismic events with low probability of breaching components of the engineered barrier system. The approach is aimed at complementing total system performance assessment models used to understand consequences of scenarios leading to radionuclide releases in geologic nuclear waste repository systems. The objective is to develop an efficient approach to estimate mean consequences associated with seismic events of low probability, employing data from a performance assessment model with a modest number of Monte Carlo realizations. The derived equations and formulas were tested with results from a specific performance assessment model. The derived equations appear to be one method to estimate mean consequences without having to use a large number of realizations.

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