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

Session 34 Abstracts
<strong>The</strong> College which had originally been funded by the UKAEA and the nuclear industry in the 1950s was anxious to break into
the new field of Decommissioning and were keen to promote these courses in order to support the work progressing on site. Many
families in Thurso, and in Caithness, have a long tradition of working in the nuclear industry and it was thought at the time that
expertise in nuclear decommissioning could be developed and indeed exported elsewhere. In addition the courses being promoted
by the College would attract students from other parts so that a centre of excellence could be established. In parallel with formal
teaching, online courses were also developed to extend the reach of the College.
<strong>The</strong> material was developed as a mixture of power point presentations and formal notes and was obtained from existing literature
web searches and interactive discussions with people in the industry as well as case studies obtained from actual situations.
Assignments were set and examination papers prepared which were validated by internal and external assessors.
<strong>The</strong> first course was started in 2004 (believed to be unique at that time) and attracted eight students. Subsequent courses have
been promoted as well as a BEng (Hons) course which also included a course on Safety and Reliability.
SESSION 34 - POSTER SESSION - LOW/INTERMEDIATE LEVEL WASTE
A) THE ROCK CREEP EVALUATION IN THE ANALYSIS SYSTEM FOR THE LONG-TERM
BEHAVIOR OF TRU WASTE DISPOSAL SYSTEM - 16110
Shintaro Ohno, Seiji Morikawa, Kajima Corporation (Japan); Morihiro Mihara, Japan Atomic Energy Agency (Japan)
MACBECE (Mechanical Analysis system considering Chemical transitions of BEntonite-based and CEment-based materials)
is an analysis system to evaluate the long term mechanical behavior in the TRU (TRans Uranium) waste disposal system. TRU
wastes are low level radioactive wastes that include long-lived nuclides. MACBECE is the system to calculate mechanical and
chemical behavior in the near field including engineered barriers in the TRU waste disposal system, and subsequently to evaluate
the hydraulic property in various components. MACBECE can evaluate the mechanical/hydraulic alterations of two types of barrier
materials, cement-based and bentonite-based materials. <strong>The</strong>se materials, in the long-term, may be altered internally by chemical
reaction. To evaluate the long-term mechanical behavior due to the chemical transitions, the nonlinear elastic model for the
cement-based materials and the elasto-viscoplastic model for the bentonite-based materials were applied, based on the data from
various laboratory tests. Also, proposed models based on the data from permeability tests were applied to evaluate the alteration of
hydraulic conductivity.
So as to realize the high reliable evaluation, the variable-compliance-type constitutive model proposed by Okubo (1992) was
newly adopted for the rock creep evaluation in MACBECE. This creep model can express analytically nonlinear visco-elastic
behavior and the over-peak-strength state behavior. This paper focuses on the adoptability of rock creep model in MACBECE.
Applicability of the rock creep model is verified by conducting the numerical simulations with the long-term mechanical interaction
between the TRU waste disposal system and the host rock.
B) COMPARISON OF ACTINIDES SEPARATION BY COPRECIPITATION AND ACTINIDE
CHROMATOGRAPHIC RESIN (DIPEX®) FOR GROSS ALPHA DETERMINATION - 16249
Esperanza Lara, Marina Rodriguez, CIEMAT (Spain)
<strong>The</strong> determination of gross alpha in wastes which have alpha, beta and gamma emitters is very important from a regulatory
point of view. <strong>The</strong> level of alpha radioactivity to storage is very limited in a low and medium level radioactive location for safety
reasons, so it is necessary to measure it with high precision.
In order to quantify the radioactive concentration of alpha emitters it is necessary to perform an adequate radiochemical separation
before its measuring.
In this paper has been studied and compared the resuls obtained by two separation methods: one by coprecipitation using
BaSO4 , Fe(OH) 3 and/or CaC2O4 as precipitant agents and the other one by extraction cromatogaraphy using Actinide Resin
(Dipex®). <strong>The</strong> separation procedures have been applied to spent ion exchange resins from Spanish Nuclear Power Plants.
Once the sample was dissolved by acid digestion in a closed vessel microwave equipment, and the radionuclides of interest
were isolated of the rest by the techniques before mentioned, the gross alpha was measrured by Liquid Scintillation Counting, using
the α/β discrimination if it was necessary (when the separation was not completed), since this technique is today one of the most
atractive and sensitive for measuring radioactivity because LS spectrometry can detect practically all types of radiation with high
efficiency.
C) NOVEL ANTIMONYSILICATE MATERIAL QUASAR-N FOR THE REMOVAL OF
RADIONUCLIDES FROM ACIDIC DECONTAMINATION LIQUIDS - 16157
Risto Harjula, Airi Paajanen, University of Helsinki (Finland)
Novel antimony silicate material, commercially available from PQ Corporation (previously Ineos Silicas) is highly selective
for the removal of several key radionuclides (Co-60, Sr-90, Cs-137, Pu-236 and Am-241) from acidic and neutral nuclear waste
effluents. <strong>The</strong> paper will summarise most the key results that have been obtained in the previous studies of the material. In addition,
new test results on the removal Co-60, Sr-90, Cs-137 and Am-241 from acid media are reported. Static batch experiments and
column experiments show that Am can be removed efficiently from nitric and oxalic acid, indicating that Quasar is suitable e.g. for
the purification of acidic decontamination solutions.
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