• Journal of Radiation Protection and Research
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• v.36 no.1
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• pp.44-51
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• 2011

Activation foil-based Bonner sphere spheres are used to obtain neutron energy spectra of nuclear power plants or accelerator-produced neutrons. The position and the foil mass dependence of response functions should be studied carefully before measurement of Bonner spheres. This study showed that the normal incidence to the foil surface made a large shift of responses while parallel and isotropic incidence made no position dependence. The correlation between foil mass and response was not linear. Therefore, the response functions of activation-foil based Bonner spheres should be calculated for every different foil mass and the direction of Bonner spheres for parallel incidence will be preferred for radioactive neutron source or accelerator target produced neutrons.

• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.162-163
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• 2010

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.223-229
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• 2017

When concrete is exposed to neutron rays for a long time, the concrete tends to become activated. If activated, it is classified as middle or low level radioactive waste. However, the great amount of the activated concrete is hard to dispose. In this study, low-activation cement was developed for decreasing the activated waste from shielding concrete around nuclear reactor. Furthermore, the manufactured low-activation was analyzed with activation nuclide Eu, Co. The low-activation cement showed great advantage for low-activation with detecting none of Eu and 3.75ppm of Co while ordinary portland cement showed 0.4~0.9ppm of Eu, 5.5~19.8ppm of Co content. As the results of physical properties of the low-activation cement, it is similar to type 1 ordinary portland cement and accords with type 4 low heat portland cement. Meanwhile, as for the chemical properties of the cement, it accords wite type 1 and 4 at the same time.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.335-341
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• 2017

Cyclotron is a device that accelerates positrons or neutrons, and is used as a facility for making radioactive drugs having short half-lives. Such radioactive drugs are used for positron emission tomography (PET), which is a medical apparatus. In order to make radioactive drugs from a cyclotron, a nuclear reaction must occur between accelerated positrons and a target. After the reaction, unncessary neutrons are produced. In the present study, radioactivation generated from the collisions between the concrete shielding wall and the positrons and neutrons produced from the cyclotron is investigated. We tracked radioactivated radioactive isotopes by conducting experiments using FLUKA, a type of Monte Carlo simulation. The properties of the concrete shielding wall were comparatively analyzed using materials containing impurities at ppm level and materials that do not contain impurities. The generated radioactivated nuclear species were comparatively analyzed based on the exposure dose affecting human body as a criterion, through RESRAD-Build. The results of experiments showed that the material containing impurities produced a total of 14 radioactive isotopes, and $^{60}Co$(72.50%), $^{134}Cs$(16.75%), $^{54}Mn$(5.60%), $^{152}Eu$(4.08%), $^{154}Eu$(1.07%) accounted for 99.9% of the total dose according to the analysis having the exposure dose affecting human body as criterion. The $^{60}Co$ nuclear species showed the greatest risk of radiation exposure. The material that did not contain impurities produced a total of five nuclear species. Among the five nuclear species, 54Mn accounted for 99.9% of the exposure dose. There is a possibility that Cobalt can be generated by inducive nuclear reaction of positrons through the radioactivation process of $^{56}Fe$ instead of impurities. However, there was no radioactivation because only few positrons reached the concrete wall. The results of comparative analysis on exposure dose with respect to the presence of impurities indicated that the presence of impurities caused approximately 98% higher exposure dose. From this result, the main cause of radioactivation was identified as the small ppm-level amount of impurities.