The 12th International Conference on Environmental ... - Events

Abstracts Session 61
According to regulations, a number of design basis cases should be identified based on scenarios that can be shown to be especially
important from the standpoint of risk. A few such cases can be derived from the results of SKBs most recent safety assessment
SR-Can. <strong>The</strong>se cases also involve several assumptions on the state of other barriers.
2) CHARACTERIZATION OF A FE-BASED ALLOY SYSTEM FOR A AFCI METALLIC WASTEFORM - 16134
Mark Williamson, Savannah River National Lab (USA); Marie Kane, Savannah River National Laboratory (USA);
Bob Sindelar, Savannah River National Lab (USA)
<strong>The</strong> AFCI waste management program aims to provide a minimum volume stable waste form for high level radioactive waste
from the various process streams. <strong>The</strong> AFCI Integrated Waste Management Strategy document has identified a Fe-Zr metallic waste
form (MWF) as the baseline alloy for disposal of Tc metal, undissolved solids, and TRUEX fission product wastes. Several candidate
alloys have been fabricated using vacuum induction melting to investigate the limits of waste loading as a function of Fe and
Zr content. Additional melts have been produced to investigate source material composition. <strong>The</strong>se alloys have been characterized
using SEM/EDS and XRD. Phase assemblage and specie partitioning of Re metal (surrogate for Tc) and noble metal FP elements
into the phases is reported.
3) THE COLLABORATIVE EU PROJECT RECOSY - 16203
Bernhard Kienzler, Gunnar Buckau, Forschungszentrum Karlsruhe (Germany)
<strong>The</strong> Collaborative Project (CP) ReCosy (Redox Controlling Systems) was established in 2008. It falls within the EURATOM
program and is implemented within the European Commission’s 7th Framework Program. Main objectives of CP ReCosy are the
sound understanding of redox phenomena controlling the long-term release/retention of radionuclides in nuclear waste disposal and
providing tools to apply the results to Performance Assessment/Safety Case. Although redox is not a new geochemical problem,
different questions are still not resolved and thus raised by implementers and scientists. Radionuclide redox transformations on minerals
are considered to be decisive scenarios in various FEP lists.
32 institutions from 13 European countries contribute to the 4-years CP by i) development of advanced analytical tools, ii)
investigations of processes responsible for redox control (thermodynamically and kinetically controlled processes, surface reactions
and microbial processes), iii) provision of required data on redox controlling processes, and iv) response of the disposal systems to
external/internal disturbances. Systems which are investigated comprise simple very well defined ones under controlled laboratory
conditions, complex laboratory systems, near-natural systems in the laboratory, real systems, and near-field systems controlled
spent nuclear fuel.
4) MODELLING RADIONUCLIDE MOBILITY OF SPENT FUEL IN A DEEP
GEOLOGICAL REPOSITORY LOCATED IN A CLAY BEDROCK - 16240
Abel Tamayo, Lara Duro, Jordi Bruno, Amphos 21 (Spain);Aurora Martínez-Esparza, ENRESA (Spain)
Source term models are widely used to assess the behaviour of spent nuclear fuel after final disposal. However, most models
do not take into account some phenomena which are expected to control the transport of radionuclides through the near field. Some
uncertainties arise from this fact, thus making it difficult to obtain proper simulations of radionuclide behaviour in the near field.
In this work, we have used a compartmental code to built up an integrated source term model which overcomes the above-mentioned
drawbacks. Such model takes into account radiolytically-mediated matrix dissolution, radioactive decay chains, diffusive
transport, and retardation by sorption and secondary phase precipitation, among other processes. In addition, this model has been
used to estimate radionuclide mobility from spent fuel located in a conceptual clay geological repository.
5) EVALUATION OF MECHANICAL EFFECTS OF THE FAULT MOVEMENT ON
THE ENGINEERED BARRIER SYSTEM - 16269
Yuya Saito, Japan Atomic Energy Agency, (Japan); Mayuka Nishimura, Takashi Hirai, Takenaka Civil Engineering &
Construction Co., Ltd, (Japan); Kenji Tanai, Morimasa Naito, Japan Atomic Energy Agency (Japan)
Experiments and numerical analyses have been conducted to investigate the consequences of an active fault crosscutting the
engineered barrier system (EBS) of a high-level radioactive waste (HLW) repository. Experiments were performed using laboratory
simulation test equipment at a scale of 1:20, which can simulate the chosen shear displacements of 80 % and 140 % of the buffer
thickness, and the chosen shear rates of 0.1 m/s, 0.05 m/s and 0.01 m/s. <strong>The</strong> experiments have so far demonstrated that the metal
overpack will be rotated, but not breached, due to the plasticity of the surrounding bentonite buffer. <strong>The</strong> total pressure on the bentonite
buffer increases with an increase in the shear rate.
6) STUDY ON PERFORMANCE ASSESSMENT FOR HLW REPOSITORY IN CHINA - 16228
Weiming Chen, Ju Wang, Rui Su, Yunfeng Li, Beijing Research Institute of Uranium Geology (China)
This paper presents the latest achievements of performance assessment (PA) for high level radioactive waste (HLW) repository
in China. <strong>The</strong> first PA model, taking Beishan granite site as an example, is established with GoldSim and is verified by comparison
with Japanese PA model. <strong>The</strong>n the behaviors of granite repository in Beishan area are simulated. <strong>The</strong> results from these simulations
show that the engineered barrier is the most important part inside the repository, especially its bentonite plays a key role
in the retardation of repository after the nuclide is released from the vitrified waste. Five sensitive parameters are identified and two
design parameters are optimized. As a result, it has been proved that performance assessment model is a necessary tool to understand
the behaviors of repository, to identify sensitive parameters, and to optimize design parameters.
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