우라늄 동위원소의 분석과 활용에 대한 고찰

김영민 대한자원환경지질학회 2023 자원환경지질 Vol.56 No.5

분석 기기의 발달과 더불어 자연 우라늄 동위원소 비(238U/235U)와 분별작용에 대한 연구가 점차 증가하고 있다. MC-ICP-MS을 이용한 우라늄 동위원소의 정밀한 분석이 가능해지면서 137.88의 고정된 값으로 여겨졌던 자연 물질의 238U/235U 비가 우라늄 동위원소 분별작용에 의해 최대 수 퍼밀까지 변화할 수 있다는 것이 밝혀졌다. 본 고찰에서는 우라늄 동위원소의 분석과 표기에 대해 간략하게 설명한 후, 지구 상 주요 물질들의 우라늄 동위원소 값(δ238U)의 변화와 지구화학적 특징을 살펴본다. 특히, 우라늄 광상의 유형과 특징에 따른 우라늄 동위원소 조성 연구 사례를 소개하고, 상대적으로 큰 δ238U 범위를 야기하는 우라늄 동위원소 분별작용에 대해 논의한다. 이를 바탕으로 고준위 방사성 폐기물 처분장의 모의 실험을 위한 자연 유사 모델로서 우라늄 광상이 갖는 연구 의의에 대해 고찰한다. Due to enhanced precision in uranium isotope measurements with MC-ICP-MS, there has been a surge in studies concerning the naturally occurring uranium isotope ratio (238U/235U) and its associated fractionation processes. Several researchers have highlighted that the 238U/235U ratio, previously assumed to be constant, can vary by several per mil depending on different natural fractionation processes. This review paper outlines the uranium isotope values (δ238U) for major terrestrial reservoirs and their variations. It discusses the range of δ238U values and uranium isotope fractionation seen in uranium ore deposits, based on deposit type and oreforming conditions. In conclusion, this paper emphasizes the importance of studies on uranium ore deposits. Such deposits serve as natural simulation models vital for designing high-level radioactive waste repository sites.

Conceptual design study on Plutonium-238 production in a multi-purpose high flux reactor

Li Jian,Zhao Jing,Liu Zhihong,She Ding,Xie Heng,Shi Lei 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1

Plutonium-238 has always been considered as the one of the promising radioisotopes for space nuclear power supply, which has long half-life, low radiation protection level, high power density, and stable fuel form at high temperatures. The industrial-scale production of 238Pu mainly depends on irradiating solid 237NpO2 target in high flux reactors, however the production process faces problems such as large fission loss and high requirements for product quality control. In this paper, a conceptual design study of producing 238Pu in a multipurpose high flux reactor was evaluated and analyzed, which includes a sensitivity analysis on 238Pu production and a further study on the irradiation scheme. It demonstrated that the target structure and its location in the reactor, as well as the operation scheme has an impact on 238Pu amount and product quality. Furthermore, the production efficiency could be improved by optimizing target material concentration, target locations in the core and reflector. This work provides technical support for irradiation production of 238Pu in high flux reactors.

Estimation of Dose Delivered to Accelerator Devices from Stripping of 18.5 MeV/n 238U Ions Using the FLUKA Code

Leila Mokhtari Oranj,이희석,Mario Santana Leitner 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.11

In Korea, a heavy ion accelerator facility (RAON) has been designed for production of rare isotopes. The 90 bending section of this accelerator includes a 1.3-μm-carbon stripper followed by two dipole magnets and other devices. An incident beam is 18.5 MeV/n 238U33+,34+ ions passing through the carbon stripper at the beginning of the section. The two dipoles are tuned to transport 238U ions with specific charge states of 77+, 78+, 79+, 80+ and 81+. Then other ions will be deflected at the bends and cause beam losses. These beam losses are a concern to the devices of transport/beam line. The absorbed dose in devices and prompt dose in the tunnel were calculated using the FLUKA code in order to estimate radiation damage of such devices located at the 90 bending section and for the radiation protection. A novel method to transport multi-charged 238U ions beam was applied in the FLUKA code by using charge distribution of 238U ions after the stripper obtained from LISE++ code. The calculated results showed that the absorbed dose in the devices is influenced by the geometrical arrangement. The maximum dose was observed at the coils of first, second, fourth and fifth quadruples placed after first dipole magnet. The integrated doses for 30 years of operation with 9.5 pμA 238U ions were about 2 MGy for those quadrupoles. In conclusion, the protection of devices particularly, quadruples would be necessary to reduce the damage to devices. Moreover, results showed that the prompt radiation penetrated within the first 60 - 120 cm of concrete.

한국 연안 퇴적물에서 ^137Cs, ^90Sr 및 Pu 동위원소의 분포

최석원,진현국,김철수,노정환,김창규,노병환 대한방사선 방어학회 2002 방사선방어학회지 Vol.27 No.2

한국 주변 연안 15개 정점의 퇴적물(0∼20 cm)에서 ^137Cs, ^90Sr, ^239+240Pu 의 농도와 농도비를 조사했다. ^137Cs, ^90Sr, ^238Pu 및^239+240Pu의 평균 방사능 농도는 각각 2.24±0.79 Bq·kg^-1-dry, 0.20±0.04 Bq·kg^-1-dry, 0.009±0.005 Bq·kg^-1-dry 및 0.27±0.17 Bq·kg^-1-dry이다. ^137Cs/^90Sr, ^239+240Pu/^137Cs 및 ^238Pu/229+240Pu의 평균 농도 비와 ^239Pu/240의 평균 원자 비는 각각 11.2±2.9, 0.123±0.053, 0.033±0.01 및 0.218±0.036이다. 퇴적물에서 핵종의 농도 범위와 핵종간의 농도 비는 그 동안 주변국가의 퇴적물에서 조사한 값과 비슷하였다. 퇴적물에서 ^137Cs과 ^239+240Pu의 상관계수는 0.80이다. ^137Cs과 SOM, ^239+240Pu과 점토 함량과의 상관계수는 각각 0.69, 0.67 이다. The concentrations and activity ratios of ^137Cs, ^90Sr, ^238Pu and ^239+240Pu in sediment(0∼20 cm) at 15 coastal stations of Korea were determined. The mean concentrations of ^137Cs, ^90Sr, ^238Pu and ^239+240Pu are 2.24±0.79 Bq·kg^-1-dry, 0.20±0.04 Bq·kg^-1-dry, 0.009±0.005 Bq·kg^-1-dry and 0.27±0.17 Bq·kg^-1-dry, respectively. The mean activity ratios of ^137Cs/^90Sr, ^239+240Pu/^137Cs and ^238Pu/^229+240Pu and atomic ratio of ^240Pu/^239Pu are 11.2±2.9, 0.123±0.053 and 0.033±0.017 and 0.218±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 ^137Cs and ^239+240Pu is 0.80. The correlation coefficient of ^137Cs and soil organic matter(SOM), and ^239+240Pu and clay content are 0.69 and 0.67, respectively.

한국토양 내 천연 방사성핵종에 의한 거주민의 방사선피폭평가

김정훈(Jung-Hoon Kim),김아름(Ah-Reum Kim),고성진(Seong-Jin Ko),황주호(Joo-Ho Whang) 대한방사선과학회(구 대한방사선기술학회) 2009 방사선기술과학 Vol.32 No.2

한국 토양내 천연방사성핵종 중 238U, 232Th, 40K 농도를 분석하여 거주민의 방사선피폭을 평가하였다. 분석결과 238U, 232Th, 40K은 각각 15.77±7.27, 290.05±73.92, 750.30±165.38 Bq/kg 값을 나타냈다. 천연방사성핵종 농도를 바탕으로 산출한 흡수선량률은 213.76±46.37 nGy/hr이며, 동일 지역에서 측정한 공간감마흡수선량률은 123.90±19.18 nGy/hr이였다. 천연방사성핵종(238U, 232Th, 40K)을 대상으로 거주민의 유효선량률은 0.26 mSv/yr로 나타나 UNSCEAR에서 제시한 세계 평균유효선량률인 0.07 mSv/yr보다 높은 값을 나타냈다. We investigated the amounts of radiation exposure from 238U, 232Th, and 40K which are three major radionuclides naturally residing in soil of the Korean peninsula. The experimental results showed that the concentrations of the radionuclides were 15.77±7.27, 290.05±73.92 and 750.30±165.38 Bq/kg respectively. The absorbed dose rate based on the measured concentrations was 213.76±46.37 nGy/hr, while the spatial gamma absorbed dose rate measured in the same region was 123.90±19.18 nGy/hr. The effective dose rate was 0.26 mSv/yr, which is significantly higher than the world average effective dose rate 0.07 mSv/yr provided by the UNSCEAR.

Activity on Mass Yield Distribution in the Photon-induced Fission of 232Th, 238U, natPb, and 209Bi at the Pohang Accelerator Laboratory

김귀년,Haladhara NAIK,Ashok GOSWAMI,V. T. NIMJE,K. C. MITTAL 한국물리학회 2015 새물리 Vol.65 No.11

We determined the yields of fission products in the photon-induced fission for 232Th and 238U with an end-point energy of 10 MeV at the electron linac of the Electron Beam Center in Kharghar, Navi Mumbai, India, and those for natPb, 209Bi, and 232Th with 45-80 MeV and 2.5 GeV at the Pohang Accelerator Laboratory in Pohang, Korea. The peak-to-valley (P/V) ratio, average light mass (<AL >), and average heavy mass (<AH >) at different excitation energies were obtained from the mass yield data of this work and literature data. The values of P/V, <AL >, and <AH > for 232Th(γ, f) and 238U(γ, f) are compared with similar data for 232Th(n, f), and 238U(n, f) to examine the role of the excitation energy in nuclear structure effects. Similarly, the present data for natPb(n, f) and 209Bi(n, f) were compared with the literature data at other bremsstrahlung energies to examine the effect of the excitation energy on the average mass (<A>) and the P/V ratio.

A preliminary study for the development of reference material using oyster for determination of ¹³⁷Cs, ⁹⁰Sr and plutonium isotopes

Lee, S.H.,Oh, J.S.,Lee, J.M.,Lee, K.B.,Park, T.S.,Lee, M.K.,Kim, S.H.,Choi, J.K. Pergamon Press 2016 Applied radiation and isotopes Vol.109 No.-

A new reference material for the determination of <SUP>137</SUP>Cs, <SUP>90</SUP>Sr and Pu isotopes (<SUP>238</SUP>Pu and <SUP>239,240</SUP>Pu) is being developed using dried oyster matrix by Korea Research Institute of Standards and Science (KRISS). The oyster was collected from Tongyoung harbour, southern part of Korea and the artificial radionuclides (<SUP>137</SUP>Cs, <SUP>90</SUP>Sr, <SUP>238</SUP>Pu and <SUP>239,240</SUP>Pu) were spiked into the material. After pretreatment and processing, the material was tested for homogeneity and massic activities were determined by measuring <SUP>137</SUP>Cs, <SUP>90</SUP>Sr, <SUP>238</SUP>Pu and <SUP>239,240</SUP>Pu. The reference value and extended uncertainty for those isotopes will be reported later.

Study on Radiation Production in the Charge Stripping Section of the RISP Linear Accelerator

오주희,Leila Mokhtari Oranj,이희석,고승국 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.3

The linear accelerator of the Rare Isotope Science Project (RISP) accelerates 200 MeV/nucleon238U ions in a multi-charge states. Many kinds of radiations are generated while the primarybeam is transported along the beam line. The stripping process using thin carbon foil leads tocomplicated radiation environments at the 90-degree bending section. The charge distribution of238U ions after the carbon charge stripper was calculated by using the LISE++ program. Theestimates of the radiation environments were carried out by using the well-proved Monte Carlocodes PHITS and FLUKA. The tracks of 238U ions in various charge states were identified usingthe magnetic field subroutine of the PHITS code. The dose distribution caused by U beam lossesfor those tracks was obtained over the accelerator tunnel. A modified calculation was applied fortracking the multi-charged U beams because the fundamental idea of PHITS and FLUKA was totransport fully-ionized ion beam. In this study, the beam loss pattern after a stripping sectionwas observed, and the radiation production by heavy ions was studied. Finally, the performanceof the PHITS and the FLUKA codes was validated for estimating the radiation production at thestripping section by applying a modified method.

부산지역 음용수 중 238U농도 분석 및 거주민의 유효선량 평가

김지민,고성진 대한방사선방어학회 2009 대한방사선방어학회 학술발표회 논문요약집 Vol.2009 No.11

Measurements of Fission Product Yield in the Neutron-induced Fission of 238U with Average Energies of 9.35 MeV and 12.52 MeV

Sadhana Mukerji,Pritam Das Krishnani,Byrapura Siddaramaiah Shivashankar,Vikas Kaluram Mulik,Saraswatula Venkat Suryanarayana,Haladhara Naik,Ashok Goswami 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.1

The yields of various fission products in the neutron-induced fission of 238U with the flux-weightedaveragedneutron energies of 9.35 MeV and 12.52 MeV were determined by using an off-line gammarayspectroscopic technique. The neutrons were generated using the 7Li(p, n) reaction at BhabhaAtomic Research Centre-Tata Institute of Fundamental Research Pelletron facility, Mumbai. Thegamma- ray activities of the fission products were counted in a highly-shielded HPGe detector overa period of several weeks to identify the decaying fission products. At both the neutron energies, thefission-yield values are reported for twelve fission product. The results obtained from the presentwork have been compared with the similar data for mono-energetic neutrons of comparable energyfrom the literature and are found to be in good agreement. The peak-to-valley (P/V) ratios werecalculated from the fission-yield data and were found to decreases for neutron energy from 9.35 to12.52 MeV, which indicates the role of excitation energy. The effect of the nuclear structure on thefission product-yield is discussed.