Confirmation of the thermal behavior of spent fuel is one of the important points in the management of high-level radioactive waste. This is because various fission products exist in spent nuclear fuel, and a management plan according to their behavior is required. Among the fission products, epsilon particles exist in the form of metal deposits and have a great influence on their physical and chemical properties. However, observing the thermal behavior of epsilon particles is important for understanding spent fuel behavior in thermally environment, but it is difficult to maintain a consistent thermal environment. In this work, we report the thermal behaviors study of uranium oxide with epsilon particle using in situ high temperature X-ray diffraction. We measured the variation of temperature on the size of crystalline, which is a cell parameter in the reaction process. And then, the change of lattice parameters is calculated by Rietveld refinement.

The large rectangular and cylindrical concrete drums are stored in nuclear power plant (NPP) for a long time. At the early stage of NPP operation, the treatment technology of boron concentrates and spent resin was not well developed, when compared to current system. Since the waste acceptance criteria (WAC) of the disposal facility was not established, the boron concentrates and spent resins were packaged in 200 L drum. Some of the 200 L drums, which contain relatively high dose rate radioactive waste, were stored in large concrete drum. The concrete drum offers superior shielding effect and allows reduction of radiation exposure to workers. The WAC requires various characteristics: radiological characteristics, physical characteristics, chemical characteristics, etc. The non-destructive method allows the rapid evaluation and estimation of the concrete structure. Also, it is expected that the large concrete exhibits integrity after the measurements. In this paper, the non-destructive method to understand the large rectangular and cylindrical drum is systematically studied. The advantage and disadvantage of the non-destructive methods were compared in this paper. In addition, the optimized methodology to characterize the radioactive waste containing large rectangular and cylindrical drum will be discussed in this paper.

During the operation of the nuclear power plant, various radioactive waste are generated. The spent resin, boron concentrates, and DAW are classified as a generic radioactive waste. They are treated and stored at radioactive waste building. In the reactor vessel, different types of radioactive waste are generated. Since the materials used in reactor core region exposed to high concentration of neutrons, they exhibit higher level of surface dose rate and specific activity. And they are usually stored in spent fuel pool with spent fuel. Various non-fuel radioactive wastes are stored in spent fuel pool, which are skeleton, control rod assembly, burnable neutron absorber, neutron source, in core detector, etc. The skeleton is composed of stainless 304 and Inconel-718. There are two types of control rod assembly, that are WH type and OPR type. The WH type control rod is composed of Ag-In-Cd composites. The OPR type control rod is composed of B4C and Inconel-625. In this paper, the characteristics and storage status of the non-fuel radioactive waste will be reported. Also, the management strategy for the various non-fuel radioactive waste will be discussed.

The segmentation of activated components is considered as a one of the most important processes in decommissioning. The activated components, such as reactor vessel and reactor vessel internals, are exposed to neutron from the nuclear fuel and classified to intermediate, low, and very low-level wastes. As it is expected, the components, which are closed to nuclear fuel, exhibit higher degree of specific activity. After the materials were exposed to neutrons, their original elements transform to other nuclides. The primary nuclides in activated stainless steel are 55Fe, 63,59Ni, 60Co, 54Mn, etc. The previous study indicates that the specific activity of individual nuclide is strongly depends on the material compositions and impurities of the original materials. The 59Co is the one of the most important impurities in stainless steel and carbon steel. In this paper, the relationship between individual nuclides in activation analysis of activated components was studied. The systematic study on specific activity of primary nuclides will be discussed in this paper to understand the activation tendency of the components.

Dry active waste (DAW) contains substantial amount of cellulose related materials. The DAW are usually classified as low and/or very low-level waste. In Korea, three types of disposal facilities have been considered: silo, engineering barrier, and land-fill. Currently, only the silo type disposal facility is in operation. Around 27 thousand drums were disposed in silo. Massive amount of cement concrete is used in construction of silo. The ground waste, which flow through the concrete structure, shows higher pH than as it is. It is generally known that the pH of silo is ~12.47 in Korea, when considering construction material, filling material, and property of ground water. It is expected that the cellulose in DAW will be partially transformed to isosaccharinic acid (ISA). It is generally accepted that the ISA plays a negative role in safety analysis of disposal facility by stimulation of specific nuclides. Various factors affect the degradation of cellulose containing radioactive waste, such as degree of polymerization, pH of disposal condition, interaction between concrete structure and ground water, etc. In this paper, the disposal safety analysis of cellulose containing radioactive, usually paper, cotton, wood, etc., are studied. The degradation of cellulose with respect to degree of polymerization, pH of neighboring water, filling material of silo, etc. are reviewed. Based on the review results, it is reasonable to conclude that the substantial amount of DAW could be disposed in silo.

본 연구는 절화용 튤립(Tulipa spp.) 4품종을 대상으로 재 식밀도에 따른 생장과 발육 특성을 알아보고 광이용효율을 분 석하여 우리나라에서 튤립 촉성재배시 필요한 기초자료를 얻 고자 실시되었다. 절화용 튤립 ‘Novi Sun’, ‘Timeless’, ‘Il de France’, ‘Dow Jones’ 4품종을 대상으로 구근용 재배 상자 (가로×세로×높이; 60cm×40cm×20cm)에 상자당 48, 70, 96개의 구근을 정식하여 저온처리 이후 비닐하우스로 운반되 었다. 그 결과, ‘Novi Sun’과 ‘Timeless’는 온실 이식 이후 35 일 만에 수확되었으며 ‘Il de France’와 ‘Dow Jones’는 그보 다 빠른 30일 만에 수확되었다. 모든 품종에서 재식밀도가 증 가할수록 생체중, 줄기 직경, 엽면적이 감소하였다. 정상개화 율은 96bulbs/box 처리에서 특히‘Novi Sun’ 32.7%과 ‘Timeless’ 4.7%로 감소하였으며 이 두 품종에서 줄기와 꽃의 건물중이 크게 감소하는 것으로 나타났다. 광이용 효율과 밀접 한 지표인 엽면적지수는 재식밀도가 높아질수록 증가하였다. 광합성 효율은 ‘Novi Sun’과 ‘Timeless’의 경우 저광도에서 재식밀도에 따라 큰 차이가 없는 것으로 나타났다. 엽면적 감 소와 형태적인 변화가 작은 ‘Il de France’과 ‘Dow Jones’에 서 광합성 효율이 크게 변화하였다. 재식밀도에 따라 다양한 생육 반응은 유사한 경향은 있으나 품종에 따라 광합성 효율과 동화산물의 분배가 크게 달라지는 것으로 나타났다. 튤립 촉성 재배 시 정상적인 꽃의 발달과 생육 확보를 위해서는 충분한 재식 간격을 확보할 수 있는 재식밀도로 정식해야 한다.

Expression changes of stress-induced peroxidase (swpa2 and swpa4) and storage root-specific sporamin (spo-A and spo-B) genes were examined using qRT-PCR after treatment with wounding and bacterial pathogens on leaves of sweetpotato (Ipomoea batatas) plants. As a result of examining the expression change in the wounding treatment condition for 48 hours after treatment, which is a representative physical stress, the expression of all genes increased after 12 hours of wounding treatment, but the expression pattern of each gene group showed distinct differences thereafter. Expression levels of swpa2 and swpa4 strongly increased up to 36 or 48 hours after wounding treatment, whereas spo-A and spo-B expression levels strongly decreased after 24 or 36 hours after wounding treatment. Peroxidase and sporamin genes are involved in the early response after wounding treatment and, in particular, the peroxidase swpa2 and swpa4 genes are also involved in the late response after wounding treatment. Gene expression analysis after infection with P. chrysanthemi, which causes softness in sweetpotato, showed that the swpa2 and swpa4 genes were weakly induced after 8 hours and then strongly induced after 20 hours during pathogen infection. Expression of the spo-A gene was weakly induced in the pathogen-treated group after 20 hours, whereas spo-B showed an expression pattern similar to that of the peroxidase genes. The above results indicate that expression of the stress-induced peroxidase gene used in this study is induced not only by abiotic stress but also by biological stress caused by bacterial pathogen invasion and that peroxidase plays an important function in the initial defense response.

Anderson-type polyoxometalate (POM) with general formula of [Hy(XO6)M6O18]n- (y=0-6, n=2-8, M=addenda atom, X=heteroatom) represents one of the basic topological structures among POM-type family. Anderson-type POMs have a planar arrangement and two terminal oxygen atoms attached to each addenda metal atom unlike other type. Thus, the Anderson-type POMs have high reactivity and various coordination modes. The various multifunctional organic-inorganic hybrid materials can be synthesized using the Anderson-type POMs as an inorganic building block. Another important feature of the Anderson-type POMs is the incorporation of the heteroatoms with various sizes and oxidation states, which can lead to tune chemical properties. No Anderson-type POMs with early transition metal ions in the heteroatom site have been reported previously. Recently, we reported the synthesis of titanium-containing Anderson-type POM, Na2K6Ti0.92W6.08O24∙12H2O (Ti-POM), which consists of pure inorganic framework built from a central Ti atom surrounded by six WO6 inorganic scaffold. Herein, in-depth studies were conducted to find optimal synthesis conditions such as composition and pH. The success of synthesis was confirmed with Powder X-ray Diffraction that the Ti-POM has a rhombohedral structure with space group of R-3m (No. 166) when the TiOSO4·xH2SO4∙yH2O/ Na2WO4∙2H2O molar ratio is in the range of 0.07 to 0.33. But outside of this range, other unwanted phases coexist. In a basic condition (pH=12), a single-phase Ti-POM with good crystallinity can be obtained, while a Keggin-type POM, NaxK10-x(H2W12O42), was formed through the decomposition of Ti-POM at pH lower than 7.

The decommissioning of nuclear power plant (NPP) consists of various activities, such system decontamination, take out of activated components, segmentation of the activated components, site remediation, etc. During various activities, the generation of radioactive wastes and radiation exposure to workers is expected. The systematic waste management during the activities is important to implement the decommissioning. The inefficient waste management usually bring significant delay in decommissioning process and results in increase of decommissioning cost. The radiation exposure management is also an important issue. It is generally accepted that the hot spot, generated from operation and decommissioning of NPP, is observed in many places within containment building. Although the health physicists measure the radiation in various points, the unintended hot spots are sometimes generated and observed. The effective radiation exposure management also requires the control of personnel and space during various activities. In this study, the radiation exposure and waste management experiences of Zion NPP is reviewed. The primary nuclides and radiation exposure during various activities are systematically studied to achieve the main objectives of this paper.

The segmentation of activated components including reactor vessel and reactor vessel internals requires many information. The primary information is material composition, trace materials in the composition, neutron flux during operation, etc. According to the EPRI report the primary basis of activity in a decommissioning source term is the activated metals from the reactor vessel and vessel internal components. The report indicates that over 95% of the radioactivity from decommissioning, except from spent nuclear fuel, consists of activated metals. These are from the reactor vessel, reactor internal structures and expendable components which are constructed primarily of various grades of stainless steel. Stainless steel contains appreciable levels of impurity cobalt. The common primary radionuclides of concern for the disposal environment from activated metals identified in US and international studies include C-14, Cl-36, Ni-59, Co-60, Ni-63, etc. The most common types of stainless steels used in reactor vessel construction and internal components include the Type 304(L), Type 316(L) and various grades of Inconel. The components of stainless steel are mainly Ni, Cr, Mo, Nb, etc., and when these elements are activated, they produce nuclides such as Nb-94, Tc-99, Sr-90, etc. In this study, the current status of activation analysis is reviewed to understand the effects of many variables. Also, the effect of trace materials is reviewed, including transformation of radioactive nuclides.

Nuclear power plant decommissioning generates significant concrete waste, which is slightly contaminated, and expected to be classified as clearance concrete waste. Clearance concrete waste is generally crushed into rubble at the site or a satellite treatment facility for practical disposal purposes. During the process, workers are exposed to radiation from the nuclides in concrete waste. The treatment processes consist of concrete cutting/crushing, transportation, and loading/unloading. Workers’ radiation exposure during the process was systematically studied. A shielding package comprising a cylindrical and hexahedron structure was considered to reduce workers’ radiation exposure, and improved the treatment process’s efficiency. The shielding package’s effect on workers’ radiation exposure during the cutting and crushing process was also studied. The calculated annual radiation exposure of concrete treatment workers was below 1 mSv, which is the annual radiation exposure limit for members of the public. It was also found that workers involved in cutting and crushing were exposed the most.

Polyoxometalates (POMs) are nanoclusters composed of transition metals with high oxidation states. Owing to their redox properties and structural diversity, POMs have been applied to broad fields, such as catalysis, materials, and medicine. Among various fields of application, POMs play an important role in radiochemistry. POMs can form complexes with tri- and tetravalent lanthanides and actinides (radioactive elements), which may be good sequestrators or agents for separating nuclear wastes. Among the most prominent POM structures, Anderson-type POMs with a general formula of [Hy(XO6)M6O18]n− (y=0–6, n=2–8, M=addenda atom, X=heteroatom) represent one of the basic topological structures of the POM family. An important feature of Anderson type POMs is incorporating a large number of various heteroatoms with different size and oxidation states, which can lead to tune chemical properties. Interestingly, no example of Anderson type POMs with early transition metal ions in the heteroatom site has been reported to date. Herein, we discovered that the Anderson POM Na2K6Ti0.92W6.08O24·12H2O, which consists of pure inorganic framework built from a central Ti core supported by six WO6 inorganic scaffold, and the crystal structure was confirmed and refined using single-crystal X-ray diffraction (SC-XRD). In addition, structural characterizations, including, Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Inductively coupled plasma-optical emission spectroscopy (ICP-OES) were performed.

The decommissioning of nuclear power plant (NPP) generates large amount of waste. Since the most of the concretes are slightly surface contaminated, the accurate characterization and regionspecific surface decontamination are important for the efficient waste management. After the effective surface decontamination and separation, most of the concrete waste from decommissioning of NPP can be classified as a clearance waste. Various surface characterization and decontamination technologies are suggested. The mechanical technologies are simple and offers direct application. The laser-based technologies offer efficient separation and surface contamination. The high price, however, hesitates the application of the process. The nitro-jet technology, which is based on the evaporation of liquid nitrogen, allows the effective decontamination. However, the high price and uncertainty of large are application hinders the practical application in NPP decommissioning. In this paper, various technologies for characterization, handling, treatment, etc., will be discussed. The advantages and disadvantages of the technologies will be discussed, in terms of practical applications.

During the decommissioning of nuclear power plant (NPP), massive amount of concrete wastes is generated, which are non-radioactive and radioactive. The concrete is a representative construction material which affords reliable structural stability, good formability, and trustful integrity. Also, its reasonable neutron absorbing property allows the various application for many components, including building construction material, bio-shield concrete, etc. Due to the noted aspects of concrete, the radiological concrete characterization is classified as an important process for development of effective strategy for concrete management, in terms of process management and financial control during the decommissioning. The characterization of bio-shield concrete is important in waste management. The understanding and characterization of activation depth is essential for the determination of waste management strategy, classification of bio-shield concrete, and process development of decommissioning. On the other hand, concrete for construction application requires the evaluation of surface contamination of them. The concrete for containment building and its structure is rarely activated, but surface contaminated. In this paper, the reactor data from representative PWR reactors in the US is studied. The experience on Yankee Rowe, Maine Yankee, and Connecticut Yankee NPPs are systematically studied. The Yankee Rowe was a 4-loop PWR of Westinghouse design with 185 MWe. The Main Yankee was a 3- loop PWR of Combustion Engineering design with 864 MWe. The Connecticut Yankee was a 4-loop Westinghouse type with 560 MWe. The characterization studies on bio-shield concrete will be discussed in this paper, including activation depth, primary nuclides, etc.

During the normal operation boron concentrates and spent resins are generated. The boron concentrates are treated by concentrated waste drying system (CWDS) and results in fine powder form. The solidification or application of high integrity container (HIC) is required for the disposal of the dried boron concentrates. The spent resin is stored in storage tank after the water treatment. The spent resin also requires solidification or application of HIC to satisfy the waste acceptance criteria (WAC) in Korea. The solidification process requires periodic validation. The repeated validation and complicated process hesitates the practical application. The application of HIC offers various advantages, including flexible free standing water requirement, higher waste loading compared to solidification, and simple process. The polymer concrete (PC), which is a primary component for PC-HIC exhibits good material stability. The expected transportation mechanism of nuclide in the PC-HIC are 1) diffusion by concentration, 2) permeation by pressure, and 3) capillary suction when considering the disposal condition. Since the PC-HIC effectively prevents the intrusion of neighboring water and volume of free standing water is lower than 1%, it seems that diffusion by concentration is the primary transportation mechanism. In this study, the property of PC is investigated based on Cl ion diffusion test to evaluate the material reliability. The results indicate that PC exhibits superior stability compared to ordinary portland cement. In addition, the reliable life time of PC is estimated base on the element transportation phenomena.