Time filter

Source Type

Chen C.-H.,National Health Research Institute | Lin F.-S.,National Health Research Institute | Liao W.-N.,National Health Research Institute | Liang S.L.,National Health Research Institute | And 15 more authors.
Analytical Chemistry | Year: 2015

This study aims to establish a 198Au-radiotracer technique for in vivo tracing, rapid quantification, and ex vivo visualization of PEGylated gold nanoparticles (GNPs) in animals, organs and tissue dissections. The advantages of GNPs lie in its superior optical property, biocompatibility and versatile conjugation chemistry, which are promising to develop diagnostic probes and drug delivery systems. 198Au is used as a radiotracer because it simultaneously emits beta and gamma radiations with proper energy and half-life; therefore, 198Au can be used for bioanalytical purposes. The 198Au-tagged radioactive gold nanoparticles (198Au-GNPs) were prepared simply by irradiating the GNPs in a nuclear reactor through the 197Au(n,γ)198Au reaction and subsequently the 198Au-GNPs were subjected to surface modification with polyethylene glycol to form PEGylated 198Au-GNPs. The 198Au-GNPs retained physicochemical properties that were the same as those of GNP before neutron irradiation. Pharmacokinetic and biodisposition studies were performed by intravenously injecting three types of 198Au-GNPs with or without PEGylation into mice; the γ radiation in blood specimens and dissected organs was then measured. The 198Au-radiotracer technique enables rapid quantification freed from tedious sample preparation and shows more than 95% recovery of injected GNPs. Clinical gamma scintigraphy was proved feasible to explore spatial- and temporal-resolved biodisposition of 198Au-GNPs in living animals. Moreover, autoradiography, which recorded beta particles from 198Au, enabled visualizing the heterogeneous biodisposition of 198Au-GNPs in different microenvironments and tissues. In this study, the 198Au-radiotracer technique facilitated creating a trimodality analytical platform for tracing, quantifying and imaging GNPs in animals. © 2014 American Chemical Society.

Chiang Y.,National Tsing Hua University | Wang J.-R.,National Tsing Hua University | Wang J.-R.,Nuclear and New Energy Education and Research Foundation | Wang T.-Y.,National Tsing Hua University | And 7 more authors.
International Congress on Advances in Nuclear Power Plants, ICAPP 2016 | Year: 2016

After Fukushima Daiichi accident, the safety analysis of severe accident became one of the safety concerns in Taiwan. The emergency operating procedure (EOP) cannot cope with a multiple system failure situation under a severe accident since it is a "Symptom-basis" procedure. To deal with that, Taiwan Power Company built up a new strategy for Fukushima-like accident called Ultimate Response Guideline (URG). It is a very simple strategy with three main conditions: Loss of regular motor driven injection system, loss of all AC power and tsunami/earthquake warning. If two of three happen, the operating procedure will change from EOP to URG and start the main works by following the strategy. There are three main works in URG: Controlled-depressurization, line up low pressure injection water and prepare containment venting. In this study, MELCOR2.1 was used to calculate the cases of URG and checked the strategy reach the goal that prevents a severe accident or not. The latest version MELCOR2.1 was used and combined with Symbolic Nuclear Analysis Package (SNAP). In this combination, MELCOR was used with a graphical user interface (GUI) that users can easily modify any detail of the model. An animation model of SNAP can also show the core degradation easily by using the results of MELCOR. There were three steps in this research. First, a model of Chinshan nuclear power plant (NPP) was built and compared the trend of some important results to MAAP5.0 in a case of SBO. Second, the MELCOR model was separated to two cases. One was the case with URG and the other was not. The results were compared to MAAP5.0, TRACE and PCTRAN and it seems the results of MELCOR were consistent with other codes. Finally, some sensitivity studies of depressurization and water injection rate were done by MELCOR2.1/SNAP. By the analysis of MELCOR, the strategy of URG successfully prevented Chinshan NPP from severe accident and kept the cladding temperature below 1088.7K. Also, the containment remained safety in the case using URG. The sensitivity studies showed that controlleddepressurization was better than fully-depressurization because the risk of cladding temperature rising was lower. The low pressure water injection rate should be higher than 150GPM (9.46kg/s) to prevent the temperature rising of cladding.

Liu H.C.,ESS Building | Lee M.,ESS Building | Liang T.K.S.,Nuclear Science and Technology Development Center
International Conference on Nuclear Engineering, Proceedings, ICONE | Year: 2012

In the Westinghouse design of Advanced Pressurized Water Reactor (AP-1000), a special design named In-Vessel Retention (IVR) is adopted to enhance the heat removal capability through outer wall of reactor vessel during a severe core melt accident. In the present study, RELAP5-3D system thermalhydraulic code is used to simulate the natural convection flow within the water channel of IVR. The results of simulation are substituted into SULTAN, and SBLB Critical Heat Flux correlations developed specifically for this purpose to access the margin of IVR design of AP1000. In the model, the cylindrical part of flow channel of IVR is represented by three-dimensional cylindrical components ?r, ⊙,z?of RELAP5-3D code. The semi-spherical shell of the flow channel is modeled by several inter-connected threedimensional cylindrical components. Each component has different radius. The results demonstrated that the critical heat flux ratio is lowest at the upper equator of the vessel. It has also been predicted that the heat removal capacity of AP1000 IVR is limited between 33 and 48.2 MW, which correspond between 0.35 and 1.08 hours after shutdown. The results demonstrated that IVR of AP1000 can terminate the progression of severe accidents if the attacks of vessel lower head starts about 70 minutes after the initiation of the accident. Copyright © 2012 by ASME.

Liu Y.-H.,Nuclear Science and Technology Development Center | Lee P.,National Tsing Hua University | Lin Y.-C.,National Tsing Hua University | Chou F.-I.,Nuclear Science and Technology Development Center | And 4 more authors.
Applied Radiation and Isotopes | Year: 2014

Dose estimation of animal experiments affects many subsequent derived quantities, such as RBE and CBE values. It is important to ensure the trustiness of calculated dose of the irradiated animals. However, the dose estimation was normally calculated using simplified geometries and tissue compositions, which led to rough results. This paper introduces the use of treatment planning systems NCTplan and Xplan for the dose estimation. A mouse was taken as an example and it was brought to hospital for micro-PET/CT scan. It was found that the critical organ doses of an irradiated mouse calculated by simplified model were unreliable in comparison to Xplan voxel model. The difference could reach the extent of several tenths percent. It is recommended that a treatment planning system should be introduced to future animal experiments to upgrade the data quality. © 2014 Elsevier Ltd.

Lee P.-Y.,National Tsing Hua University | Liu Y.-H.,Nuclear Science and Technology Development Center | Jiang S.-H.,National Tsing Hua University
Applied Radiation and Isotopes | Year: 2014

High energy proton beam (>8MeV) is favorable for producing neutrons with high yield. However, the produced neutrons are of high energies. These high energy neutrons can cause severe fast neutron contamination and degrade the BNCT treatment quality if they are not appropriately moderated. Hence, this study aims to briefly discuss the issue, from the viewpoint of fast neutron contamination control, whether high energy proton beam is ideal for AB-BNCT or not. In this study, D2O, PbF4, CaF2, and Fluental™ were used standalone as moderator materials to slow down 1-, 6-, and 10-MeV parallelly incident neutrons. From the calculated results, we concluded that neutrons produced by high energy proton beam could not be easily moderated by a single moderator to an acceptable contamination level and still with reasonable epithermal neutron beam intensity. Hence, much more complicated and sophisticated designs of beam shaping assembly have to be developed when using high energy proton beams. © 2014 Elsevier Ltd.

Jan B.Y.-L.,Chien Hsin University of Science and Technology | Tsai S.-C.,Nuclear Science and Technology Development Center | Li Y.-Y.,National Tsing Hua University
Journal of Radioanalytical and Nuclear Chemistry | Year: 2014

Sorption and diffusion are important processes for the transport of radionuclides through geomedia from a radioactive disposal facility. In this study, batch tests and through-diffusion experiments were performed to investigate the sorption and diffusion of Se(IV) in crushed granite. Different column lengths of 2, 4 and 8, were employed in the through-diffusion experiments to study the effect of the column length on the apparent diffusion coefficients. Synthetic groundwater (GW) and synthetic seawater (SW) were the liquid phases in these experiments. A two-site kinetic linear model and the Freundlich isotherm were applied to match the sorption/desorption batch data quite closely for both of GW and SW conditions. The retardation factors (R f ) were estimated by comparing the breakthrough curve of Se(IV) with that of HTO. Experimental results indicated that whether in GM or SW solution, the column lengths did not significantly affected D a or R f of Se in crushed granite. © 2014 Akadémiai Kiadó.

Loading Nuclear Science and Technology Development Center collaborators
Loading Nuclear Science and Technology Development Center collaborators