• 방사성폐기물학회지
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• 제4권1호
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• pp.1-7
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• 2006

염산매질에서 산화/환원제를 사용하여 Pu 산화수를 조절한 후, UV-Visible-Near IR 분광기를 이용하여 Pu(III, IV, V, VI) 산화수에 대한 흡수스펙트럼을 측정하여 그 분광학적 특성을 고찰하였다. Pu(III)으로 조절하기 위하여 환원제인 $NH_2OH$ HCl를 사용하였으며, Pu(IV)와 Pu(VI)로 조절하기 위하여 산화제인 $NaNO_2$ 및 $HClO_4$를 각각 사용하였다. 또한 Pu(VI)로 조절된 용액에 환원제인 $NH_2OH$ HCl를 사용하여 Pu(V)로 조절하였다. Pu(III)와 Pu(IV)의 대표적인 흡수피크는 470 nm 및 600 nm에서 각각 관찰되었고, Pu(VI)와 Pu(V)의 특성피크는 830 nm 및 1135nm에서 각각 관찰되었다. Pu(III, IV, VI) 산화상태의 시간 경과에 따른 흡수스펙트럼 변화는 관찰되지 않았으나 Pu(V)의 경우 매우 불안정하여 생성되자 마자 Pu(III)로 변화되었다.

• 공업화학
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• 제9권2호
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• pp.172-176
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• 1998

에폭시 adduct carboxyl terminated butadiene acrylonitrile(CTBN)은 CTBN과 에폭시수지를 블렌딩하여 제조하였다. CTBN과 폴리우레탄(PU) 및 에폭시수지로 CTBN/PU/epoxy를 제조하였다. CTBN이 5 wt%에서 CTBN/PU/Epoxy는 PU의 함량이 증가할 수록 damping 피크가 이동하였다. PU의 함량이 증가할수록 상용성이 증가함을 의미한다. 그러나 CTBN의 함량이 증가함에 따라 상용성은 감소하였다. CTBN/PU/epoxy에서는 PU의 함량이 10wt%에서 최대 굴곡값을 나타냈으나, PU 함량이 증가할수록 감소하였다. CTBN/epoxy에서 PU를 첨가함에 따라 파괴인성은 증가하였다. 파괴단면에서 전단변형과 공동화에 의한 응력백화현상을 보였다. CTBN의 공동화와 PU를 도입한 에폭시 매트릭스의 전단변형이 CTBN/PU/epoxy의 강인화기구이다.

• 방사성폐기물학회지
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• 제21권1호
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• pp.55-64
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• 2023

There is a gap in our understanding of the behavior of fused and molten fuel salts containing unavoidable contamination, such as those due to fabrication, handling, or storage. Therefore, this work used calorimetry to investigate the change in liquidus temperature of PuCl₃, having an unknown purity and that had been in storage for several decades. Further research was performed by additions of NaCl, making several compositions within the binary system, and summarizing the resulting changes, if any, to the phase diagram. The melting temperature of the PuCl₃ was determined to be 746.5℃, approximately 20℃ lower than literature reported values, most likely due to an excess of Pu metal in the PuCl₃ either due to the presence of metallic plutonium remaining from incomplete chlorination or due to the solubility of Pu in PuCl₃. From the melting temperature, it was determined that the PuCl₃ contained between 5.9 to 6.2mol% Pu metal. Analysis of the NaCl-PuCl₃ samples showed that using the Pu rich PuCl₃ resulted in significant changes to the NaCl-PuCl₃ phase diagram. Most notably an unreported phase transition occurring at approximately 406℃ and a new eutectic composition of 52.7mol% NaCl-38.7mol% PuCl₃-2.5mol% Pu which melted at 449.3℃. Additionally, an increase in the liquidus temperatures was seen for NaCl rich compositions while lower liquidus temperatures were seen for PuCl₃ rich compositions. It can therefore be concluded that changes will occur in the NaCl-PuCl₃ binary system when using PuCl₃ with excess Pu metal. However, melting temperature analysis can provide valuable insight into the composition of the PuCl₃ and therefore the NaCl-PuCl₃ system.

• 방사성폐기물학회지
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• 제5권2호
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• pp.103-108
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• 2007

질산, 불산 및 과염소산을 사용하여 플루토늄 옥사이드 $(PuO_2)$을 녹여 Pu 기준용액을 제조한후 UV-Visible-Near IR 분광기를 이용하여 Pu 흡수 스펙트럼 특성을 관찰하였다. 산성, 중성 및 알칼리 매질에서 Pu(III), Pu(IV) 및 Pu(VI)에 대한 분광학적 특성을 조사하였다. 또한 알칼리 및 산 농도 증가에 따른 Pu(VI) 흡수 스펙트럼에 대한 특성 피크 세기 및 위치를 관찰하였다. 염산 및 수산화나트륨 매질에서 환원제 첨가에 따른 Pu(VI) 산화수 변화를 측정하였다.

• 분석과학
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• 제19권1호
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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.

• Environmental Engineering Research
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• 제11권1호
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• pp.1-13
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• 2006

In this study, conventional biofilters packed with flexible synthetic polyurethane (PU) foam carriers were operated to remove toluene from a contaminated air stream. PU foams containing various adsorbents (e.g., zeolite, sepiolite, dolomite and barite) were synthesized for the biofilter media and their adsorption characteristics of toluene were determined. Adsorption capacity of PU-adsorbent foam was in the order of PU-dolomite ${\approx}$ PU-zeolite > PU-sepiolite > PU-barite. During the biofiltration experiment, influent toluene concentration was in the range of 0-160 ppm and EBRT (i.e., empty bed residence time) was 45 seconds. Pressure drop of the biofilter bed was 4-5 mm $H_2O/m$ column height. The maximum removal capacity was in the order of PU-dolomite > PU-zeolite > PU-sepiolite > PU-barite, while the complete removal capacity was in the order of PU-dolomite > PU-sepiolite > PU-zeolite > PU-barite. The better biofiltration performance in PU-dolomite foam was because PU-dolomite foam had lower density and higher porosity than the others providing favorable conditions for microbial growth. The results of biodegradation kinetic analysis showed that PU-dolomite foam had higher maximum removal rate ($V_m\;=\;11.04\;g$ toluene/kg dry material/day) and saturation constant ($K_s\;=\;26.57\;ppm$) than the other PU foams. This supports that PU-dolomite foam was better than the others for biofilteration of toluene.

• Journal of Radiation Protection and Research
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• 제35권3호
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• pp.117-123
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• 2010

Pu 동위원소는 기원에 따라 각기 다른 $^{240}Pu/^{239}Pu$ 동위원소비를 나타내는 특성이 있다. 질량분석법은 극미량 장반감기핵종 분석에 매우 유용한 방법으로서 검출기 특성상 낮은 검출한계를 갖고 있으며, 소량의 시료를 이용하여 짧은 시간에 측정을 할 수 있다는 장점을 갖고 있으므로 Pu을 비롯한 장반감기 핵종 분석에 유용하다. 다중검출기유도결합플라즈마질량분석기(Multicollector ICP-MS)는 다중검출시스템을 이용하여 분석하고자 하는 여러 핵종의 동시분석이 가능하며, 특별히 본 연구에서는 극미량 핵종의 검출이 가능한 multiple ion counter (MIC)를 사용하여 Pu 동위원소 분석에 적용하였다. 본 연구방법의 검출한계(detection limit)는 최적화된 조건에서 $^{239}Pu$와 $^{240}Pu$ 각각 $0.10\;fg\;ml^{-1}$ ($0.24\;{\mu}Bq\;ml^{-1}$), $0.12\;fg\;ml^{-1}$ ($0.97\;{\mu}Bq\;ml^{-1}$)이었으며, 240Pu 기준으로 약 200 cps 정도의 매우 낮은 농도수준에서 1%이하의 $^{240}Pu/^{239}Pu$ 동위원소비 계측편차를 나타내었다. 본 연구방법은 표준용액 및 다양한 매트릭스의 표준물질 분석에 적용함으로써 검증 확인하였다.

• 분석과학
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• 제17권6호
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• pp.514-519
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• 2004

BOMARC 미사일 발사대 주변에서 채취한 토양에 대하여 입자크기에 따른 Pu 및 Am 방사능 분석 및 동위원소를 측정하였다. BOMARC 토양에서의 Pu와 Am 방사능 농도는 핵실험에 의해 생성된 방사능 낙진 준위보다 매우 높았으며, 입자크기가 증가함에 따라 감소하는 경향을 보여주었다. BOMARC 토양에서 측정한 Pu-238 / Pu-239, 240, Pu-241 / Pu-239, 240 및 Am-241 / Pu-239, 240 방사능비는 핵실험에 의해 생성된 방사능 낙진에 대한 방사능 농도비 보다 약간 낮은값을 나타내었다. ICP-MS로 측정한 Pu-240 / Pu-239 질량비는 북반구 대기권 핵실험 및 체르노빌 원전사고에 의한 질량비보다 매우 낮은 값을 나타내었고, Greenland Thule 지역에서 핵무기를 탑재한 B52 비행기 사고로 방출된 핵무기에 대한 질량비와 비슷한 값을 나타내었다. BOMARC 토양에서 측정된 Pu 및 Am 동위원소들의 방사능비 및 질량비로부터 BOMARC 토양에 오염된 Pu는 핵무기용 Pu로부터 생성되었다고 판단된다.

• Fibers and Polymers
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• 제4권2호
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• pp.49-53
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• 2003

Polyurethane (PU) layer and copolymer consisted of the different molecular weights (1000 and 2000 g/mol) of poly(propylene glycol) (PPG) were prepared. The damping and mechanical properties of these materials were compared with PU 1000 made by PPG having the molecular weight of 1000 g/mol. The optimum composition of PU2000 used for PU layer and copolymer was diphenylmethane diioscynate (MDI)/propylene glycol (PPG)/butanediol (BD) (1/0.3/0.7) based on the damping and mechanical properties. The damping peak of PU copolymer was higher than those of PU layer and PUI 1000 in low temperature range (-30- $10^{\circ}C$). For application in noise reduction, the transmission loss of the mechanical vibration through solid structure was measured. PU layer and copolymer were used as a damping layer. The transmission loss of PU copolymer was more effective than those of PU layer and PU 1000 in the experimental frequency range.

• Nuclear Engineering and Technology
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• 제13권3호
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• pp.139-144
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• 1981

Pu-244와 Xe-136반응에서 생성된 Pu, Np 및 U을 분리하여 그 핵반응 단면적을 측정하였다. 핵반응단면적은 각각 $\sigma$($^{245}$ Pu)=66 mb, $\sigma$($^{243}$ Pu)=57 mb, $\sigma$($^{246}$ Pu)=6.0 mb, $\sigma$($^{239}$ Np)=15 mb, $\sigma$($^{240}$ U)=12 mb, $\sigma$($^{241}$ U)=6.4 mb이었다.