• Nuclear Engineering and Technology
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• v.21 no.4
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• pp.277-286
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• 1989

Destructive methods are used for the turnup determination of an irradiated PWR fuel. One of the methods includes U, Pu, Nd-148 and Nd-(145+146) determination by an isotope dilution mass spectrometry using triple spikes (U-233, Pu-242 and Nd-150). The method involves two sequential ion exchange resin separation procedures. Pu is eluted from the first anion exchange resin column (Dowex AG 1$\times$8) with 12 M HCl-0.1 M HI mixed solution, followed by U elution with 0.1 M HCl. Nd is isolated from other fission products on the second anion exchange resin column (Dowex AG 1$\times$4) with a nitric acid-methanol eluent. Each fraction is analysed by thermal ionization mass spectrometry. The difference between Nd-148 and Nd-(145+146) method is found with an average 2.07%. The results are compared with those by the heavy element method using U and Pu isotopes and by the destructive y-spectrometric measurement of Cs-137. The dependences of isotope composition of U and Pu on burn-up, and correlation between those isotopes are illustrated graphically.

• Nuclear Engineering and Technology
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• v.13 no.3
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• pp.139-144
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• 1981

Plutionum, neptunium, and uranium isotopes which were produced in the interaction of $^{136}$ Xe and $^{244}$ Pu are separated and determined their cross sections. The cross sections are: $\sigma$($^{245}$ Pu)=66 mb, $\sigma$($^{243}$ Pu)=57 mb, $\sigma$($^{246}$ Pu)=6.0 mb, $\sigma$($^{239}$ Np)=15 mb, $\sigma$($^{240}$ U)=12 mb, $\sigma$($^{245}$ U)=6.4 mb respectively.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.11a
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• pp.407-408
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• 2009

In this work, a quantitative method of the sequential separation of $^{90}Pu,\;^{90}Sr$ and $^{241}Am$ nuclides was developed in environmental soil samples using by an anion exchange resin connected with a Sr Spec resin. The sequential methods of Pu, $^{90}Sr$ and $^{241}Am$ nuclides can reduce analysis cost and time. With the sequential methodupdated in this study, the activity concentrations of $^{239,240}Pu,\;^{90}Sr$ and $^{241}Am$ in the IAEA reference materials were close to the reference values reported by the IAEA.

• Analytical Science and Technology
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• v.19 no.1
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• pp.18-30
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• 2006

This paper describes the cumulative deposition of fallout Pu in soil and lichen at the present time and give the characteristics of fallout Pu deposits in the soil. In the soil of the forest, the accumulated depositions of $^{239,240}Pu$ were estimated to be in the range of 34.0 to $101.2Bq\;m^{-2}$ with an average value of $65.3{\pm}21.6Bq\;m^{-2}$. The average inventory of $^{239,240}Pu$ in the forest was calculated to be two times higher than that in the hill. Also, the deposited activities of $^{239,240}Pu$ in cultivated soil were significantly lower than those in the hill or forest. However, the cumulative depositions of fallout Pu in the volcanic ash soil on Cheju Island were much higher than those in the forest and hill soils. The measured activity concentrations of Pu isotopes in lichens and mosses showed large variations, due to characteristics of species and life span of lichen and moss colonies. From depth profiles, it was found that most of the fallout Pu has been accumulated in upper 10 cm layer of soil. Except for a few cases, the concentrations of $^{239,240}Pu$ in soil tended to decrease exponentially with increasing soil depth. Among parameters affecting the cumulative deposition of fallout Pu, organic substances and rainfall play an important role in the retention and relative mobility of fallout Pu in the soil. However, pH showed a weak correlation with the deposition of fallout Pu in the soil. From sequential leaching experiments, Pu was found to be associated predominantly with the "organic" and "oxy-hydroxy" fractions. Both the activity ratios of $^{238}Pu/^{239,240}Pu$ and $^{241}Pu/^{239,240}Pu$ in soils, lichens and mosses and the atomic ratios of $^{240}Pu/^{239}Pu$ in soils are close to those observed in the cumulative deposit global fallout from nuclear weapon testings. The results obtained from this research make it possible to interpret and predict the behavior of fallout Pu under natural conditions.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.3
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• pp.167-174
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• 2009

A comprehensive analysis has been conducted on the purity of the uranium product generated from a pyroprocessing of EBR-II spent fuel. The analysis results were compared to the low-level waste criteria for both ROK and USA under a collaborative program between INL and KAERI. It is found that the US LLW definition does not include the activity from any U isotopes, but the Korean one does. The analysis results show that Pu-239 is the only alpha emitting isotope other than U isotopes that exceed the limit in the EBR-II U product. Pu contamination of the product seems to be drastically reduced in a preliminary test of the modified cathode process, and the further development of the proposed technology may be possible to meet the US LLW criteria.

• Nuclear Engineering and Technology
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• v.52 no.4
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• pp.674-680
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• 2020

We used MCNP6 computer code to model HTR-10 core reactor. We used two types of fuel; UO₂ and (Th+Pu)O₂ mixture. We determined the critical height at which the reactor approached criticality in both two cases. The neutronic and burnup parameters were investigated. The results indicated that the core fueled with mixed (Th+Pu)O₂, achieved about 24% higher fuel cycle length than the UO₂ case. It also enhanced safeguard security by burning Pu isotopes. The results were compared with previously published papers and good agreements were found.

• Journal of Radiation Protection and Research
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• v.35 no.3
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• pp.117-123
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• 2010

Plutonium is by far the most important of the transuranic elements which have been released into the environment due to radio-toxicity and long term radiation effects on humans. And Pu isotope ratio ($^{240}Pu/^{239}Pu$) is of great interest because this ratio is used as a fingerprint for different sources. Mass spectrometry has been used as an useful atom counting technique with several advantages over decay counting techniques for the determination of Pu isotopes. It enables a determination of Pu isotope ratio in the environmental samples with a low detection limit and a short determination time. An ICP-MS is the representative mass spectrometry for Pu determination. In this study, the precision of $^{240}Pu/^{239}Pu$ isotope ratio was improved by using 4 multiple ion counters of MC-ICP-MS. The detection limit of $^{239}Pu$ and $^{240}Pu$ were $0.10\;fg\;ml^{-1}$ ($0.24\;{\mu}Bq\;ml^{-1}$), $0.12\;fg\;ml^{-1}$ ($0.97\;{\mu}Bq\;ml^{-1}$), respectively. The relative standard deviation of $^{240}Pu/^{239}Pu$ isotope ratio was less than 1 % in trace level. The various reference materials (seawater, soil and sediment) were analyzed to verify this method and their analytical results were in good agreement with the certified (or recommended value) value.

• Journal of Radiation Protection and Research
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• v.27 no.2
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• pp.101-110
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• 2002

The concentrations and activity ratios of $^{137}Cs,\;^{90}Sr\;^{238}Pu$ and $^{239-240}Pu$ in sediment($0sim}20\;$cm) at 15 coastal stations of Korea were determined. The mean concentrations of $^{137}Cs,\;^{90}Sr\;^{238}Pu$ and $^{239-240}Pu$ are $2.24{\pm0.79\;Bq{\cdot}kg^{-1}-dry,\;0.20{\pm}0.04 Bq{\cdot}kg^{-1}-dry,\;0.009{\pm}0.005\;Bq{\cdot}kg^{-1}-dry}$ and $0.27{\pm}0.17\;Bq{\cdot}kg^{-1}-dry$, respectively. The mean activity ratios of $^{137}Cs,\;^{90}Sr$, $^{239-240}Pu/^{137}Cs$ and $^{238}Pu/^{229-240}Pu$ and atomic ratio of $^{240}Pu/^{239}Pu$ are $11.2{\pm}2.9,\;0.123{\pm}0.053$ and $0.033{\pm}0.017$ and $0.218{\pm}0.036$, respectively. The concentrations and activity ratios in sediment samples are similar to those reported from neighbouring country in the northern hemisphere. The correlation coefficient of $^{137}Cs$ and $^{239-240}Pu$ is 0.80. The correlation coefficient of $^{137}Cs$ and soil organic matter(SOM), and $^{239-240}Pu$ and clay content are 0.69 and 0.67, respectively.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.673-682
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• 2007

The contents of transuranic elements in high-burnup spent fuel samples were determined. The activity amounts of $^{238}Pu,\;^{239}Pu,\;^{240}Pu,\;^{241}Am,\;^{244}Cm\;and\;^{242}Cm$ were measured by alpha spectrometry using $^{242}Pu\;and\;^{243}Am$ as tracers, respectively. A spike addition method for $^{237}Np$ was established by an alpha and gamma spectrometry using $^{239}Np$ as a spike after the optimum conditions for the measurements of $^{237}Np\;and\;^{239}Np$, respectively, were obtained. A separation system using anion exchange chromatography and diethylhexylphosphoric acid extraction chromatography was applied for the separation of these elements. This method was applied to high-burnup spent nuclear fuel samples $(40{\sim}60GWD/MTU)$. The contents of the transuranic elements were compared with those by ORIGEN-2 code. Measurements and the calculations of the contents of the plutonium isotopes $^{238}Pu,\;^{239}Pu\;and\;^{240}Pu$ agreed to within 10% on average. The contents of $^{237}Np$ agreed to within approximately 5% except for one instance of a calculation, while those of $^{241}Am,\;^{244}Cm\;and\;^{242}Cm$ showed higher values by approximately 19%, 35% and 14% on average, respectively, compared to the calculations according to the burnup.

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.44-45
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• 2011