Transparent Tools for Uncertainty Analysis in High Level Waste Disposal Facilities Safety

2007 ◽  
Author(s):  
Francisco Luiz de Lemos ◽  
Karl-Heinz Helmuth ◽  
Terry Sullivan
Keyword(s):  
Fuzzy Logic ◽  
Uncertainty Analysis ◽  
Waste Disposal ◽  
Computational Models ◽  
Cognitive Mapping ◽  
Data Interpretation ◽  
High Level Waste ◽  
Rock Interaction ◽  
And Migration ◽  
High Level

In this paper some results of a further development of a technical cooperation project, initiated in 2004, between the CDTN/CNEN, The Brazilian National Nuclear Energy Commission, and the STUK, The Finnish Radiation and Nuclear Safety Authority, are presented. The objective of this project is to study applications of fuzzy logic, and artificial intelligence methods, on uncertainty analysis of high level waste disposal facilities safety assessment. Uncertainty analysis is an essential part of the study of the complex interactions of the features, events and processes, which will affect the performance of the HLW disposal system over the thousands of years in the future. Very often the development of conceptual and computational models requires simplifications and selection of over conservative parameters that can lead to unrealistic results. These results can mask the existing uncertainties which, consequently, can be an obstacle to a better understanding of the natural processes. A correct evaluation of uncertainties and their rule on data interpretation is an important step for the improvement of the confidence in the calculations and public acceptance. This study focuses on dissolution (source), solubility and sorption (sink) as key processes for determination of release and migration of radionuclides. These factors are affected by a number of parameters that characterize the near and far fields such as pH; temperature; redox conditions; and other groundwater properties. On the other hand, these parameters are also consequence of other processes and conditions such as water rock interaction; pH and redox buffering. Fuzzy logic tools have been proved to be suited for dealing with interpretation of complex, and some times conflicting, data. For example, although some parameters, such as pH and carbonate, are treated as independent, they have influence in each other and on the solubility. It is used the technique of fuzzy cognitive mapping is used for analysis of effects of variations on one parameter on the others in a system. This technique uses the concept of fuzzy sets to represent the “quality” of the relation between parameters rather then deterministic numbers.

THE USE OF CERAMIC SPONGES FOR HIGH LEVEL WASTE DISPOSAL

1964 ◽  
pp. 543-571
Author(s):  
C.W. CHRISTENSON ◽  
R.G. THOMAS ◽  
W.H. ADAMS ◽  
E.B. FOWLER ◽  
G.D. KELLY
Keyword(s):  
Waste Disposal ◽  
High Level Waste ◽  
High Level

Geological Disposal for High-Level Waste: Ethical Considerations

2001 ◽  
Author(s):  
Gustaaf C. Cornelis
Keyword(s):  
Time Scales ◽  
Waste Disposal ◽  
High Level Waste ◽  
Ethical Considerations ◽  
Technical Aspects ◽  
Geological Disposal ◽  
High Level

Abstract This paper describes the activities launched at SCK•CEN, intended to explore ethical and other non-technical aspects when dealing with the time scales considered in the high-level waste disposal program. (1) Especially the issues of retrievability and precaution will be focused on philosophically. Many questions will be raised in order to sensitize all stakeholders for the transdisciplinary character of the transgenerational problem at hand.

Simultaneous resolution of reactive radioactive decay, non-isothermal flow, and migration with application to the performance assessment for HLW repositories

2010 ◽  
Vol 98 (6) ◽  
Author(s):  
R. Juncosa ◽  
I. Font ◽  
J. Delgado
Keyword(s):  
Ion Exchange ◽  
Radioactive Decay ◽  
Chemical Species ◽  
High Level Waste ◽  
Chemical Components ◽  
Clay Material ◽  
Decay Series ◽  
And Migration ◽  
High Level ◽  
Radioactive Species

AbstractRadioactive decay is an important subject to take into account when studying the thermo-hydro-dynamic behavior of the buffer clay material used in the containment of radioactive waste. The modern concepts for the multibarrier design of a repository of high level waste in deep geologic formations consider that once canisters have failed, the buffer clay material must ensure the retention and/or delay of radionuclides within the time framework given in the assessment studies. Within the clay buffer, different chemical species are retarded/fixed according to several physicochemical processes (ion exchange, surface complexation, precipitation, matrix diffusion, ...) but typical approaches do not consider the eventuality that radioactive species change their chemical nature (The radioactive decay of an element takes place independently of the phase (aqueous, solid or gaseous) to which it belongs. This means that, in terms of radionuclide fixation, some geochemical processes will be effective scavengers (for instance mineral precipitation of crystal growth) while others will not (for instance ion exchange and/or sorption).In this contribution we present a reactive radioactive decay model of any number of chemical components including those that belong to decay series. The model, which is named FLOW-DECAY, also takes into account flow and isotopic migration and it has been applied considering a hypothetical model scenario provided by the project ENRESA 2000 and direct comparison with the results generated by the probabilistic code GoldSim. Results indicate that FLOW-DECAY may simulate the decay processes in a similar way that GoldSim, being the differences related to factors associated to code architecture.

scholarly journals Impact of Partitioning and Transmutation on LWR High-Level Waste Disposal

2008 ◽  
Vol 45 (1) ◽  
pp. 84-97 ◽  
Author(s):  
Kenji NISHIHARA ◽  
Shinichi NAKAYAMA ◽  
Yasuji MORITA ◽  
Hiroyuki OIGAWA ◽  
Tomohiko IWASAKI
Keyword(s):  
Waste Disposal ◽  
High Level Waste ◽  
High Level ◽  
Partitioning And Transmutation

Multibarrier Copper-Base Containers for High-Level Waste Disposal

1993 ◽  
Vol 104 (2) ◽  
pp. 219-232 ◽  
Author(s):  
Dale T. Peters ◽  
Konrad J. A. Kundig ◽  
David F. Medley ◽  
Paul A. Enders
Keyword(s):  
Waste Disposal ◽  
High Level Waste ◽  
Copper Base ◽  
High Level

scholarly journals A citizens workgroup helps researchers reflect on their work

2021 ◽  
Vol 1 ◽  
pp. 211-213
Author(s):  
Roman Seidl ◽  
Cord Drögemüller ◽  
Pius Krütli ◽  
Clemens Walther
Keyword(s):  
Waste Disposal ◽  
Personal Experience ◽  
Point Of View ◽  
Academic Disciplines ◽  
High Level Waste ◽  
Value Similarity ◽  
Social Sciences And Humanities ◽  
Mediating Role ◽  
State Of Research ◽  
High Level

Abstract. In our transdisciplinary project (http://www.transens.de) several academic disciplines work on questions and solutions for high-level nuclear waste disposal in Germany. Adding to this interdisciplinary setting, in our sub-project on trust, we have enlisted a group of 16 citizens (citizens workgroup, CWG), reflecting with us on our research with regard to research questions and approaches. In this talk, we present results from a joint workshop of researchers and the CWG on the role of trust in scientists. We want to understand how participants perceive and relate to science and how this may affect trust in scientists and experts. During a first workshop (conducted online in March 2021), the CWG members were allocated to three breakout groups (1)–(3) to discuss three guiding questions: a. What expectations do you have of a scientist from Social Sciences and Humanities (SSH)/Natural Sciences and Engineering (NSE) in the TRANSENS project? b. What characterizes a scientist from SSH/NSE that you trust? c. What would have to happen for you to no longer trust him/her? The group in breakout room (1) was asked to answer questions (a)–(c) for a fictitious SSH researcher. The group in breakout room (2) was asked to do the same for a fictitious NSE researcher. The group in breakout room (3) was asked whether they perceived differences in the trust of SSH and NSE researchers. For SSH we found that a scientist should be sympathetic and non-condescending, represent a neutral point of view, and consider all opinions. Remarkably, discussants in this group struggled to define a role for SSH scientists in high-level waste disposal research. Some participants ascribed SSH a moderating or mediating role. If necessary (e.g. communication of results), mediation between the NSE and the public can be added. SSH scientists may train other scientists with regard to their performance. Participants stated that scientists from NSE should present information in full and clarify the current state of research (provisional nature of knowledge acknowledged). A scientist should not conceal any information, uncertainties, or risks, be neutral and objective, have experience in the field (professionalism, experience, reputation), and not exclusively reproduce one's own opinion or spread untruths. In all groups, participants judged the NSE as “harder”, more serious and more tangible. It was also discussed that the scientist's appearance is of great importance and that a scientist can “pick up” the audience in an exciting way when communicating. Personal experience was mentioned several times in all groups as a basis for trust. These results match findings on the effect of value similarity (Siegrist et al., 2000, and own survey in 2020 in Germany): If a person is perceived as advocating similar values, it is more likely that I trust that person. Personal experience of – among other issues – similar values may increase trust. Moreover, and importantly, trust also emerges when participants know exactly how issues will be considered, e.g. if input from the CWG is considered or not – and if not: why? In general, participants want to be taken seriously. Thus, transparent and binding rules for all participants may be key for a relationship of trust.

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