Wide-area surface decontamination is essential during the sudden release of radioisotopes to the public, such as nuclear accidents or terrorist attacks. A spray coating composed of a reversible complex between poly (vinyl alcohol) (PVA) and phenylboronic acid-grafted poly (methyl vinyl ether-alt-mono-sodium maleate) (PBA–g–PMVE–SM) was developed to remove radioactive cesium from surfaces. The simultaneous spay of PVA and PBA–g–PMVE–SM aqueous polymer solutions containing Cs adsorbent to contaminated surfaces resulted in the spontaneous formation of a PBA–diol ester bond-based gel-like coating. The Cs adsorbent suspended in the gel-like coating selectively removed Cs-137 from the Cs-contaminated surface. The used gel-like coating were removed from surfaces by simple water rinsing. This recovery way has advantages compared with costly incineration to remove the organic materials for final disposal/storage of the radioactive waste. Thus, our spray coating is suitable for practical wide-area surface decontamination. In radioactive tests, the hydrogel containing Cs-adsorbent showed substantial Cs-137 removal efficiencies of 96.996% for painted cement and 63.404% for cement, which are 2.33 times better than the values for the commercial surface decontamination coating agent DeconGel.

The magnetic Cs adsorbent functionalized with hierarchical titanium-ferrocyanide were fabricated for the highly efficient magnetic removal of radioactive cesium from water. The new magnetic Cs adsorbent has a core–shell structure that comprises a Fe3O4 core, an interlayer of SiO2, and a titanium-ferrocyanide-shell with hierarchical nanostructure. At first, the magnetic Fe3O4 nanoparticles synthesized via a hydrothermal reaction were coated with SiO2. Then, TiO2 were coated on the surface of SiO2 coated magnetic nanoparticles. Finally, the hierarchical titanium-ferrocyanide composed of 2-dimensional TiFC flakes was fabricated on the surface of core-shell MNP@SiO2@TiO2 microparticles using a TiO2 sacrificial template via a simple reaction with potassium ferrocyanide (FC) based on the Kirkendall-type diffusion. The resulting magnetic Cs adsorbent shows higher adsorption capacity of 416 mg/g than other magnetic Cs adsorbents (below 200 mg/g) because of the increased effective surface area of hierarchical titanium-ferrocyanide. Therefore, our Magnetic Cs adsorbent functionalized with hierarchical titanium-ferrocyanide has excellent potential for the treatment of various 137Cs-contaminated sources.

Radioactive cesium is a heat generated and semi-volitile nuclide in spent nuclear fuel (SNF). It is released gasous phase by head-end treatment which is a pretreatment of pyroprocessing. One of the capturing methods of gasous radioactive cesium is using zeolite. After ion-exchanged zeolite, it is transformed to ceramic waste form which is durable ceramic structure by heat treatment. Various ceramic wasteforms for Cs immobilization have been researched such as cesium aluminosilicate (CsAlSi2O6), cesium zirconium phosphate (CsZr2(PO4)3), cesium titanate (CsxAlxTi8-xO16, Cs2TiNb6O18) and CsZr0.5W1.5O6. The cesium pollucite is composed to aluminosilicate framework and cesium ion incorporated in matrix materials lattices. Many researchers are reported that the pollucite have high chemical durability. In this study, the Cesium pollucite was fabricated using mixtures of aluminosilicate denoted Absorbent product (AP) and Cs2CO3 by calcination and pelletized by cold pressing. The characterization of fabricated pollucite powder and pellets was analyzed by XRD, TGA, SEM, SEMEDS and XRF. The chemical durability of pollucite powder was evaulated by PCT-A and ICP-MS and OES. Thus, the optimal pressure condition without breaking the pellets which is low Cs2O/AP ratio and pelletizing pressure was selected. The long-term leaching test was performed using MCC-1 method for 28 days with the fabricated pollucite pellets. The leachate of leaching test was allard groundwaster and Deionized water and replaced 5 contact periods which is 3 hours, 3 days, 7 days, 14 days and 28 days and analyzed by ICPMS. The leaching rate was shown two stages. The first stage was rapid and relatively large amount of nuclides were leached. The leaching rate was decreased in the second stage. The fractional release rate of this study was shown same trend. These results were similar to previous studies.

오염수로부터 자성분리가 가능하며, 방사성 세슘을 효율적으로 제거하기 위한 코발트 페로시아나이드(cobalt ferrocyanide, CoFC) 혹은 니켈 페로시아나이드(nickel ferrocyanide, NiFC)가 도입된 자성입자 흡착제를 제조하였다. Fe3O4 나노 입자는 공침법을 이용해 제조하였고, Co2+와 Ni2+ 이온을 입자 표면에 도입시키기 위해 금속이온과 금속 배위결합(metalcoordination) 을 하는 카르복실기를 포함한 숙신산(succinic acid, SA)을 자성나노입자(magnetic nanoparticles, MNPs) 표 면에 코팅하였다. CoFC와 NiFC는 자성나노입자 표면에 도입된 Co2+ 혹은 Ni2+ 이온이 hexacynoferrate와 결합하여 형성된 다. 제조된 CoFC-MNPs 그리고 NiFC-MNPs는 각각 43.2 emu·g-1, 47.7 emu·g-1의 우수한 포화자화 값을 보여주었다. X- 선 회절분석(XRD), 퓨리에 변환 적외선 분광분석(FT-IR), 나노입자 입도 분석기(DLS), 투과전자현미경(TEM) 등의 분석을 통해 흡착제의 물성을 파악하고, 세슘에 대한 흡착 성능을 알아보았다. 흡착실험을 평가하기 위해 Langmuir/Freundlich 등 온흡착식을 이용해 실험 결과 값을 곡선맞춤 하였고, CoFC-MNPs와 NiFC-MNPs의 최대흡착량(qm)은 각각 15.63 mg·g-1, 12.11 mg·g-1이다. CoFC-MNPs와 NiFC-MNPs는 방사성 세슘에 대해서도 최저 99.09%의 제거율을 가지며, 경쟁이온의 존재에도 방사성 세슘만을 선택적으로 흡착한다.

원자력 발전소 중대사고에 의해 방사성 세슘(137Cs)이 지하수계로 유출될 경우를 가정하여, 연구 지역의 깊이에 따른 암석매질의 특성을 규명하고 세슘의 흡착계수를 정량적으로 평가하였다. 대상지역인 신고리 원전 3, 4호기의 지하 암석매질은 주로 석영 및 장석류로 이루어진 화강암 계열이며, 운모류를 10~20% 함유하고 있다. 비교적 얕은 심도(6.3~7.4 m)의 파쇄대에서 2차 광물인 녹니석이 일부 포함되어 있었지만, 기반암에서는 거의 발견되지 않았다. 137Cs의 흡착분배계수(Kd)는 파쇄대 지역에서 약 880~960 mL/g로 기반암 지역에서의 820~840 mL/g보다 비교적 높게 나타났으며, 이는 파쇄대에 포함되어 있는 풍화생성물인 2차 광물들에 의한 영향으로 판단된다. 따라서 137Cs이 지하 매질로 유출될 경우 대부분은 천부 지역에 흡착되어 세슘에 의한 오염 확산 속도가 지연될 것이라고 예상되며, 이러한 결과는 원자력 발전소 안정성 평가인자 자료로 활용될 것으로 기대된다.