[en] It has been reported that the effect of thermal redistribution of hydrides across the metal-oxide interface, coupled with thermal feedback on the metal-oxide interface, is a dominating factor in the accelerated oxidation in zirconium alloys cladding PWR fuel. Especially the precipitated and redistributed hydrides are known to relieve the stress imposed onto the metal / oxide interface during the waterside corrosion of zirconium alloys. Without the hydrides the stress exceeds the critical value of 3GPa which induce the tetragonal-ZrO₂ phase formation. Therefore, in this study enhanced oxidation due to the precipitated hydrides are experimentally confirmed and the stress on the interface is measured with in-situ bend test using steam beam in order to support the stress relieve hypothesis of hydride precipitates. Prior to the bend test the enhancement of zirconium oxidation due to hydride precipitates are experimentally revealed by the in-situ and intermittent weight gain measurement during the oxidation reaction. Through these measurements, it is confirmed that hydride precipitate enhances and sometimes accelerates the oxidation reaction rate and the enhancements augments with reaction temperature increase. Steam beam bend test disclose that the stress imposed onto the metal / oxide interface surely exceeds the critical 3 GPa inducing tetragonal zirconium oxide formation. In actuality, the highest stress measured in the test is 2.9 GPa with about 0.1 μm oxide thickness. It is well-known that the stress increases rapidly with the decreasing oxide thickness. In the following study, the stress relieve due to the hydride precipitation will be experimentally verified

[en] By considering the biological properties of a tumor, it should be possible to realize better results in cancer therapy. PET imaging offers the opportunity to measure tumor growth non-invasively and repeatedly as an early assessment of response to cancer therapy. Measuring cellular growth instead of energy metabolism showed offer significant advantages in evaluating therapy. Thymidine and its derivative nucleoside compounds can be changed to mono, di-and tri- phosphate compounds by thymidine kinase and then be incorporated into DNA. Their bindings are increased in highly proliferating cells due to the high DNA synthesis rate. To evaluate cell proliferation, many kinds of thymidine and uridine derivatives have been labeled with positron emitter and radioactive iodine. Compared to radiopharmacuticals which have radioisotope labeled base ring such as pyirmidine, the radiopharmaceuticals which have radioisotope labeled sugar ring are more stable in vivo and have metabolic resistance. The biological properties such as DNA incorporation ratios are highly dependent on their chemical structures and metabolic processes. This overview describes synthesis of radiopharmaceuticals and their biological properties for imaging of tumor cell proliferation

[en] Neurotransmitter imaging with radiopharmaceuticals plays major role for understanding of neurological and psychiatric disorders such as Parkinson's disease and depression. Radiopharmaceuticals for neurotransmitter imaging can be divided to dopamine transporter imaging radiopharmaceuticals and serotonin transporter imaging radiopharmaceuticals. Many kinds of new dopamine transporter imaging radiopharmaceuticals has a tropane ring and they showed different biological properties according to the substituted functional group on tropane ring. After the first clinical trials with [¹²³I] β -CIT, alkyl chain substituent introduced to tropane ring amine to decrease time for imaging acquisition and to increase selectivity. From these results, [¹²³I]PE2I, [18F]FE-CNT, [¹²³I]FP-CIT and [¹⁸F]FP-CIT were developed and they showed high uptake on the dopamine transporter rich regions and fast peak uptake equilibrium time within 4 hours after injection. [¹¹C]McN 5652 was developed for serotonin transporter imaging but this compound showed slow kinetics and high background radioactivity. To overcome these problems, new diarylsulfide backbone derivatives such as ADAM, ODAM, AFM, and DASB were developed. In these candidates, [¹¹C]AFM and [¹¹C]DASB showed high binding affinity to serotonin transporter and fast in vivo kinetics. This paper gives an overview of current status on dopamine and serotonin transporter imaging radiopharmaceuticals and the development of new lead compounds as potential radiopharmaceuticals by medicinal chemistry

[en] To improve fire safety of operating nuclear power plants, fire hazard analysis should be performed periodically after initial analysis at design stage. Therefore, according to plant-specific fire hazard analysis, it requires appropriate action to improve fire protection features and programs correspond with safety codes and standards. Fire hazard analysis is to analyze whether nuclear power plant is capable of safe shut down and radiation protection ultimately. It fulfilled to minimize occurrence and scale of a fire by appropriate design of fire prevention, detection and suppression systems and to avoid loss of safe shutdown function from fire hazard. It is possible to estimate design basis fire by calculation of fire loadings from fixed and transient combustibles to evaluate potential fire vulnerabilities and fire barrier structures during fire hazard analysis. Method to estimate fire loadings and severity can be used by engineering estimation, experimental result, and computational analysis, also which should be enough to assume combustibles conservatively. In this paper, we describe method to determine fire barrier ratings in fire risk assessment for operating nuclear power plants

[en] In the industry, globe valves, which are commonly used to precise control the flow rate along with opening and closing flow in pipes, are technically and economically limited in valve size due to structural instability related to complex internal flow passage. Butterfly valves, on the other hand, have advantages such as low weight and low manufacturing costs, but it is difficult to control the flow rate at an opening angle of 60°or higher and flow is unstable in the case of butterfly valve. Therefore, the purpose of this study is to have characteristics of flow rate of the globe valve that is used in the industry at the same diameter of pipeline and flow stability due to uniformity of flow through the baffle hole by adding 1/2 baffle to butterfly valve. Hole size of baffles were set at 5, 7 and 9 mm and baffles were set at the rear of the butterfly valve. To verify the method of numerical analysis, the results of experimental study were compared with the results of numerical study. As a results, it is confirmed that characteristics of flow rate of butterfly valve with baffle is similar to globe valve in the case of hole size 5 mm. In addition, flow pattern is to be stable by analyzing turbulence energy. Consequently, when applying baffle to butterfly valve, it is possible to reduce the flow unstability and change the flow rate of butterfly valve.

[en] We prepared 3'-deoxy-3'-[¹⁸F]fluorothymidine ([¹⁸F]FLT) from 3'-O-nosyl thymidine derivative 3 or its pyrimidine ring N-BOC-protected analogue 5 and optimized [¹⁸F]fluorination condition for a high radiochemical yield. The optimal condition for [¹⁸F]fluorination with precursor 3 was 30 mg (41.1 μmol)/300 μl CH₃CN at 130 degree sign C for 5 min, while precursor 5 required 34 mg (40 μmol)/300 μl CH₃CN at 110 degree sign C for 5 min. After HPLC purification at neutral pH, we achieved high radiochemical yields of 40 ± 5.2% and 42 ± 5.4% (decay-corrected) within 60 min of preparation time with radiochemical purities of >97%

[en] In order to prove fire safety of operating nuclear power plants, plant-specific fire hazard analysis should be performed. Furthermore the effect of design changes on fire safety should be reviewed periodically. At the estimating fire vulnerability stage, the factors that influence fire vulnerability include ignition sources, combustibles, fire barriers, fire protection features such as detection, alarm, suppression, evacuation are investigated. At the stage of fire hazard assessment, ignition and propagation hazard, passive and active fire protection features, and fire protection program such as pre-fire plan and related procedures are investigated. Based on the result of fire hazard analysis, reasonable improvement plan for fire protection can be established. This paper describes the result of fire hazard analysis classified by fire area for turbine building of which fire hazards and fire frequencies are relatively high in operating nuclear power plant

[en] We evaluated a rapid preparation procedures for the labeling and quality control of ^99mTc-ECD, MAG₃ and MIBI using microwave heating and Sep-Pak cartridges. ^99mTc labeling of ECD, MAG₃, and MIBI kit preparation was performed according to the package inserts with microwave heating modification. Heating time was 10-15 sec, and heating was performed with 3 mm plastic bottle with screw cap to prevent radiation contamination. Labeling efficiency was obtained with C₁₈ or Alumina N Sep-Pak cartridges. The radiochemical purity of 93 ∼ 96% for ^99mTc-ECD and 95 ∼ 99% for ^99mTc-MIBI was obtained using Alumina N Sep-Pak cartridge. The optimum irradiation time of microwave method for 3 ml ^99mTc-labeled radiopharmaceutical solution was 10 sec for ^99mTc-ECD and ^99mTc-MIBI, and 15 sec for ^99mTc-MAG₃. The results of quality control data with Sep-Pak cartridges were well correlated wth TLC method. The total preparation time of these radiopharmaceuticals was 5 ∼ 6 min including quality control procedure. This study demonstrates that radiopharmaceuticals preparation by microwave heating and quality control by Sep-Pak cartridges can be efficiently utilized as an alternative to the recommended method by manufacture's manual

[en] We describe here the synthesis of ^99mTc-ciprofloxacin by four different methods and its biodistribution. All of the methods gave high radiochemical yields of ≥90% and high stability of ≥90% at 6 h after preparation. However HPLC analysis, bacterial binding assay, and in vivo distribution for the four ^99mTc-ciprofloxacins showed different results. Among these methods, the use of formamidine sulfinic acid with microwave heating (Method A) was fast and easy, and gave more desirable biological properties than the other methods

[en] ^99mTc-Ciprofloxacin is a potentially specific agent for bacterial infection. The aim of this study was to find out whether ^99mTc-Ciprofloxacin accumulation can differentiate bacterial infectious inflammation from nonbacterial sterile inflammation. ^99mTc-Ciprofloxacin was synthesized with ^99mTc 20 mCi, ciprofloxacine 2 mg, formamidine sulphinic acid 1 mg, and 15 sec heating in microwave. For induction of infectious or sterile inflammation in SD rats, 2 x 10⁸ of S. aureus in 0.2ml (group1, n=9) or 0.2 ml of terpentine oil (group 2, n=10) were injected to thigh muscle. Three days later, ^99mTc-Ciprofloxacin images were obtained at 4 hrs after iv injection of 37MBq of ^99mTc-Ciprofloxacin. Immediately after imaging, rats were sacrificed and dissected to obtain %ID/g of normal organs and inflammatory lesions. For histopathologic evaluation, tissue specimens from the inflammatory lesions were obtained. The induction of infection/inflammation produced marked swelling of thighs in both groups. ^99mTc-Ciprofloxacin imaging of both groups showed increased uptake, but target to background uptake ratio in group 1 was significantly higher than group 2 (3.70±0.5 vs 2.18±0.3, p<0.05). From the biodistribution data, accumulation of ^99mTc-Ciprofloxacin in liver, slpeen, kidney were 6.1±0.45, 5.1±0.42, 3.42±0.2%ID/g, respectively, and inflammatory lesion in group 1 and group 2 were 0.42±0.09 and 0.24±0.02%ID/g, respectively. Both lesion to normal muscle activity ratio and lesion to blood activity ratio of ^99mTc-Ciprofloxacin in group 1 were significantly higher than group 2 (5.29±2.3 vs 1.69±0.2, 1.45±0.47 vs 0.93±0.2, p<0.005). On histopathology, both types of inflammatory lesions showed marked accumulation of leukocytes, and many microorganisms were also shown in infectious lesion. ^99mTc-Ciprofloxacin uptake is significantly higher in bacterial infectious inflammation than sterile inflammation. However, further studies and cautious clinical application are needed for differentiating infectious from sterile inflammation using ^99mTc-Ciprofloxacin imaging, because there is still significant degree of ^99mTc-Ciprofloxacin accumulation in sterile inflammation