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

Abstracts Session 12
joint awareness that cooperation on the scientific, technical, and social challenges related to geological disposal is needed, and the
cooperation will be beneficial for the timely and safe implementation of the first geological disposal facilities. Such a demonstration
of a viable solution for the management of high-level radioactive waste will enhance stakeholder confidence in Europe. Several
decades of research, development and demonstration (RD&D) have been carried out in the field of geological disposal. <strong>International</strong>
opportunities of cooperation and establishing a technology platform were explored in the European Commission co-funded
projects like Net.Excel and CARD. According to the CARD project, the majority of the funding for RD&D in waste management
comes from the implementing organizations.
G) WVP MELTER ANALYSIS AND MODELLING FOR LIFETIME EXTENSION - 16209
Clare Booth, Sellafield Sites (UK); Mark D’Vaz, Sellafield Ltd (UK)
<strong>The</strong> purpose of the Sellafield Waste Vitrification Plant (WVP) is to immobilise highly active liquors produced during reprocessing
of magnox and oxide fuel operations by means of a Vitrification process bonding the fission products as metal oxides into
a borosilicate glass matrix. This provides the stability required for safe long term storage of waste fuel products.
Over the last two years the WVP technical department has carried out a study in prolonging the life of the melter vessels used
within WVP. <strong>The</strong> melter vessel is a critical part of the vitrification process. <strong>The</strong> purpose of this vessel is a crucible in which to heat,
mix and react glass and fission products (as a calcine) and pour the glass product into a stainless steel container for long term storage.
Several research projects have been carried out in partnership with the National Nuclear Laboratory to further understand the
failure mechanisms within the melter vessel. Research has been focused in two areas:
• <strong>The</strong> metallographic destructive examination of two inactive melters used to simulate plant conditions experienced within
WVP active lines with respect to thermal recycling and corrosion attack. From relating this work to plant process data such
as thermal cycling temperatures and HAL chemical composition, a set of operation parameters can be established with the
intention of prolonging the life of the melter vessels within WVP.
• <strong>The</strong> development of modelling techniques. <strong>The</strong> models have been designed to simulate a variety of operating conditions
and aim to predict behaviour of the vessel and melt in a large variety of control regimes, and glass characteristics for a
large set of feed compositions. From this information we can formulate operating envelopes that extend the life of the
melter vessel by anticipating required operating conditions given different feedstocks and mitigating or postponing primary
failure modes.
H) FEBEX IN SITU TEST - SHOWING THE VALUE OF VERY LONG TERM (>10 YEARS) EXPERIMENTS - 16422
Irina Gaus, NAGRA (Switzerland); Erik Thurner, SKB (Sweden); Marjut Vahanen, Posiva, (Finland);
Pedro Luis Martín Martín, CIEMAT (Spain); Juan Carlos Mayor, ENRESA (Spain);
Jose Luis García-Siñeriz, Aitemin, (Spain); Antonio Gens, UPC (Spain)
<strong>The</strong> FEBEX experiment at the Grimsel Test Site (GTS) consists of an in-situ full-scale engineered barrier system (EBS) test
for the disposal of high level waste (HLW) performed under natural conditions.
With heating starting in 1997 and led by Enresa, the FEBEX experiment, is the longest running experiment of its scale and has
been the research subject in three subsequent European projects. In 2008, a consortium of four partners (SKB, Ciemat, Posiva,
Nagra) continued running the experiment under the project name FEBEXe until at least 2012, when excavation of the second and
last heater is planned.
<strong>The</strong> experiment is based on the Spanish reference concept in crystalline rock in which the canisters are placed horizontally in
drifts and surrounded by a clay barrier constructed of highly compacted bentonite blocks. A constant temperature of 100°C has been
maintained, while the bentonite buffer has been slowly hydrating in a natural way. A total of 632 sensors were installed in the clay
barrier, the rock mass, the heaters and the service zone to measure the following variables: temperature, humidity, total pressure,
displacement, water pressure etc. Partial dismantling and sampling of the in-situ test was carried out during 2002.
Although one of the main goals of the experiment has been fulfilled (demonstrating the feasibility of handling and constructing
the EBS), with the length of the dataset increasing, the observed thermo-hydro-mechanical (THM) and thermo-hydro-geochemical
(THG) behaviour has revealed several features of interest, such as the underestimation of re-saturation times and the degree of
uncertainty in key parameters.
I) PARTITIONING RATIOS AMONG SOLID-, LIQUID-, AND GAS-PHASES FOR C-14
LABELED SODIUM ACETATE IN PADDY AND UPLAND SOILS - 16112
Nobuyoshi Ishii, National Institute of Radiological Sciences (Japan)
In Japan, transuranic (TRU) waste is grouped into four types. Group 2 type includes hulls and end pieces, which contain significant
amounts of C-14. As C-14 is long-lived, soluble and has little sorption properties, it is the key nuclide in safety assessment
for a geological repository of TRU waste.
Recently, the possibility of leaching of organic carbon compounds from hull waste has been reported. However, there is little
information for reliable migration data sets of such organic C-14. Thus, it is hard to deny any possible migration of organic C-14
from a TRU repository site to the sphere of human habitation.
To assess human expose to C-14 through crops intake, it is necessary to understand the behavior of organic C-14 in agricultural
fields. In this study, we determined solid-, liquid-, and gas-partitioning ratios of organic C-14 in paddy and upland soils by using
batch cultures. Investigation of factors affecting the partitioning ratios between paddy soils and upland soils was also carried out.
Paddy soils (n = 63) and upland soils (n = 79) were collected from throughout Japan. Each of these agricultural soils was flooded
with deionized water at a solid-liquid ratio of 1:10 in a bottle. <strong>The</strong> flooded samples supplemented with [1, 2-14C] sodium acetate
were shake-incubated for 7 days. At the end of incubation, radioactivites of C-14 in the soil suspension and the supernatant were
counted by using liquid scintillation counting. Values of the sample pH were measured at the end of incubation.
69