ASME Message

Abstracts
measurement technique. By projecting a fringe pattern onto a target surface and observing its deformation due to surface
irregularities from a different view angle, FTP is capable of determining the height (depth) distribution (and hence
volume distribution) of the target surface, thus reproducing the profile of the target accurately under a wide variety of
conditions. Hence FTP has the potential to be utilized for quantitative determination of residual wastes within Hanford
waste tanks. In this paper, efforts to characterize the accuracy and precision of quantitative volume determination using
FTP and the use of these results to optimize the FTP system for deployment within Hanford waste tanks are described.
5) 40120 – Implementation of Decommissioning Materials Conditional Clearance Process to the OMEGA
Calculation Code
Matej Zachar, Vladimir Necas, Slovak University of Technology (Slovakia);
Vladimir Daniska, DECONTA a.s. (Slovakia)
The activities performed during nuclear installation decommissioning process inevitably lead to the production of
large amount of radioactive material to be managed. Significant part of materials has such low radioactivity level that
allows them to be released to the environment without any restriction for further use. On the other hand, for materials
with radioactivity slightly above the defined unconditional clearance level, there is a possibility to release them
conditionally for a specific purpose in accordance with developed scenario assuring that radiation exposure limits for
population not to be exceeded. The procedure of managing such decommissioning materials, mentioned above, could
lead to recycling and reuse of more solid materials and to save the radioactive waste repository volume. In the paper an
implementation of the process of conditional release to the OMEGA Code is analyzed in details; the Code is used for
calculation of decommissioning parameters. The analytical approach in the material parameters assessment, firstly,
assumes a definition of radiological limit conditions, based on the evaluation of possible scenarios for conditionally
released materials, and their application to appropriate sorter type in existing material and radioactivity flow system.
Other calculation procedures with relevant technological or economical parameters, mathematically describing e.g. final
radiation monitoring or transport outside the locality, are applied to the OMEGA Code in the next step. Together with
limits, new procedures creating independent material stream allow evaluation of conditional material release process
during decommissioning. Model calculations evaluating various scenarios with different input parameters and
considering conditional release of materials to the environment are performed to verify the implemented methodology.
Output parameters and results of the model assessment are presented, discussed and concluded in the final part of the
paper.
6) 40183 – Quantitative determination of the initial components in the activated pressure tubes of the Wolsong
1st CANDU reactor
Gwang-Min Sun, Dong-Keun Cho, KAERI (Korea Rep.)
When the end of the original lifespan is coming for the Wolsong 1st CANDU reactor in Korea, decommissioning
has been one of the largest issues requiring large expense, which is facing the nuclear industry and the government.
Korean government intends to provide public funds, which have been accumulated using a portion of the electrical
charge, to dismantle reactors when the time comes. The radioactive sources in the construction stuffs and components of
reactor such as pressure tube, steam generator and so on must be evaluated for the estimation of appropriate expense for
the decommissioning. The overall objective of this study is to confirm the methods for the elemental or isotopic analysis
of the pressure tube samples from nuclear reactor in order to make possible the reliable application of the methods to the
case of the Wolsong 1st CANDU reactor. To achieve this objective we need to categorize the methods into two groups
taking into account the applicability of the methods to the target we have interests in. The radiochemical analytical
methods such as liquid scintillation counting, X-ray spectroscopy and normal gamma-ray spectroscopy and so on to
measure the trace isotopic beings such as 60Co, 94Nb, 54Mn, 55Fe, 59Ni, 63Ni and so on. Elemental analysis methods
such as instrumental neutron activation analysis (INAA) and prompt gamma activation analysis (PGAA) to measure the
initial compositions of the samples. In present work, we will deal with INAA and PGAA to determine an elemental
composition of the pressure tube. The prepared samples are irradiated in the NAA #1, NAA #2 and SNU-KAERI PGAA
facility of the HANARO research reactor in Korea Atomic Energy Research Institute. Because the samples are from
pressure tube of reactor, the most abundant element must be iron and other elements can be determined relative to the
iron content. From this idea, we determined the initial elemental composition of the samples through two-step procedure.
For the absolute determination of iron content in the sample, the count rate must be calibrated according to the iron
elemental content as shown in figure 8 where the slope of the line is a specific count rate or analytical sensitivity given in
cps/?g. The relative mass of other elements in the samples were determined by using a k0-standardization method which
has been usually used in the INAA and also in the PGAA.
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