The 13th International Conference on Environmental ... - Events

paper.
Abstracts
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. <strong>The</strong> 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. <strong>The</strong> 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. <strong>The</strong> 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. <strong>The</strong> 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. <strong>The</strong> 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.
SESSION R3: ER Techniques
1) 40286 – Sequential Extraction and Determination of Depleted Uranium in the Presence of Natural Uranium in
Environmental Soil samples by ICP-MS
Mohamed Amr, Alaa E. Negmeldin, Khalid Al-Saad, A. T. Al-Kinani, Qatar University (Qatar);
A. I. Helal, Atomic Energy Authority (Qatar)
Determination of depleted uranium (DU) in the presence of natural uranium (NU) by inductively coupled plasma
mass spectrometry (ICP-MS) was applied on environmental soil samples collected from Qatar. <strong>The</strong> soils were artificially
spiked by soaking them in a mixture of DU and NU. <strong>The</strong> detection limit of 235U and 238U isotopes were 141 ppt and
1.28 ppt, respectively. It was observed from sequential experiment that uranium was brought into solution mainly
appeared at steps for dilute acid-soluble, carbonate-bound and organic matter-bound species. Little redistribution was
observed at steps for exchangeable and Fe-Mn oxide-bound species.
2) 40096 – Determination of Environmental Uranium Concentration by Utilizing Gamma-ray Emission from the
Progeny Radionuclides
Tadao Tanaka, Taro Shimada, Takenori Sukegawa, JAEA (Japan); Takeshi Ito, Japan ATOX Co., Ltd. (Japan)
Nuclear facility sites such as enrichment plant and fabrication plant are allowed to be released from nuclear safety
regulations after the plants are decommissioned. <strong>The</strong> sites are necessary to confirm to be decontaminated, prior to be
released.
Gamma-ray emission from the progeny radionuclides of uranium such as Th-234, Pa234m, Ra-226 has been utilized
for the determination of uranium concentration in soils. Gamma-ray emission radionuclides occurring in spacious areas
of land was often measured by the in-situ method with portable germanium semiconductor detector (portable Ge
detector), to confirm that there is no significant gamma-ray emission radionuclides distributed in the vast land areas. In
the present study, we proposed a determination method for U-238 concentration of background level in environment and
for probate of vast site areas, in which the gamma-ray radioactivities from Th-234, Pa-234m, Ra-226 are measured with
the portable Ge detector.
Validity of the estimation method of U-238 concentration from the progeny radionuclides was examined by the
comparison between the U-238 concentration estimated by the in-situ method with portable Ge detector and that directly
measured by ICP-MS. <strong>The</strong> U-238 concentration by the in-situ method was estimated from peak counting rate at 63 keV
of the gamma-ray emission corresponding to Th-234 and from that at 186 keV corresponding to Ra226. <strong>The</strong> estimated
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