Development of CMC for nuclear fuel components

Please click Additional Files below to see the full abstract

Performance of the TPC with Micro Pixel Chamber Readout: micro-TPC

Micro-TPC, a time projection chamber(TPC) with micro pixel chamber($\mu$-PIC) readout was developed for the detection of the three-dimensional fine(sub-m illimeter) tracks of charged particles. We developed a two-dimensional position sensitive gaseous detector, or the $\mu$-PIC, with the detection area of 10$\times$10 cm${}^{2}$ and 65536 anode electrodes of 400 $\mu$m pitch. We achieved the gas gain of over 10000 without any other multipliers. With the pipe-line readout system specially developed for the $\mu$-PIC, we detected X-rays at the rate as high as 7.7 Mcps. We attached a drift cage with an 8 cm drift length to the $\mu$-PIC and developed a micro-TPC. We measured the basic performances of the micro-TPC and took three-dimensional tracks of electrons. We also developed a prototype of the MeV gamma-ray imaging detector which is a hybrid of the micro-TPC and NaI(Tl) scintillators and confirmed its concept by reconstructing the obtained data.Comment: 6 pages 16 figures, submitted for IEEE/TNS 200

Continuous Observations of the Ground Deformations Related to the Matsushiro Earthquakes

In order to investigate the relations between ground deformations and seismic activities in Matsushiro and neighbouring regions, continuous observations on the ground tilt and strain were carried out at Matsushiro and Suzaka. At Matsushiro, three tiltmeters of horizontal pendulum type and two extensometers of bow-string type were installed in the underground gallery bored into Zozan hill, the western suburb of Matsushiro Town. At Suzaka, two tiltmeters of water tube type and two tiltmeters of horizontal pendulum type were installed in the underground gallery bored halfway up Kamatayama hill, the western suburb of Suzaka City. As to Matsushiro, it was observed that the velocity of the ground tilt sometimes changed before the occurrence of an earthquake. As to Suzaka, it proved that the direction of the ground tilt changed markedly every time an earthquake of a magnitude larger than 5.0 occurred, and an anomalous ground tilt appeared before the occurrence of the earthquakes of Sep. 27, 1966, and Feb. 8, 1967

Performance of a micro-TPC for a time-resolved neutron PSD

We report on the performance of a micro-TPC with a micro pixel chamber($\mu$-PIC) readout for a time-resolved neutron position-sensitive detector(PSD). Three-dimensional tracks and the Bragg curves of protons with energies of around 1 MeV were clearly detected by the micro-TPC. More than 95% of gamma-rays of 511 keV were found to be discriminated by simple analysis. Simulation studies showed that the total track length of proton and triton emitted from the $\rm {}^{3}He$(n,p(573 keV))$\rm {}^{3}H(191 keV)$ reaction is about 1.2 cm, and that both particles have large energy losses ($\rm > 200 keV/cm$) in 1 atm Ar+$\rm C_{2}H_{6}(10$+${}^{3}$He($< 1$). These values suit the current performance of the micro-TPC, and we conclude that a time-resolved neutron PSD with spatial resolution of sub-millimeters shall be developed as an application of the micro-TPC.Comment: 13 pages, 10 figures, to appear in NIM

Simulation study of electron drift and gas multiplication in Micro Pixel Chamber

The physical processes of charge collection and gas multiplication of a Micro Pixel Chamber (mu-PIC) were studied in detail using a three-dimensional simulation. The collection efficiencies of primary electrons and gas multiplication factors were calculated for several electrode structures. Based on those studies, we analyzed the optimization of the electrode structure of the mu-PIC, in order to obtain a high gas gain of more than 10^4 and a simultaneous suppression of discharges. Consequently, we found that these characteristics strongly depend on the substrate thickness and the anode diameter of the mu-PIC. In addition, a gas gain of 10^5 would be expected for a mu-PIC having a thick substrate of > 150um.Comment: 16 pages, 14 figures, Submitted to Nucl. Instr. Methods

Correlation of Heat Shock Protein Expression to Gender Difference in Development of Stress-Induced Gastric Mucosal Injury in Rats

Recent studies have indicated that heat shock proteins (HSPs), which function as molecular chaperones, play important roles in cellular responses to stress-related events. However, the gender difference in the expression of HSP in the gastric mucosa remains unclear. In order to understand the mechanism of gender difference in the prevalence or severity of gastric mucosal lesions, the expression level of HSP and the correlation of estrogen to HSP induction in the gastric mucosa were evaluated in this study. The basal expression levels of HSP60 and HSP90 in the gastric mucosa were significantly higher in females than those in males. The gastric ulcer index was significantly higher in male rats compared to female rats observed after 12 h water immersion stress exposure. At this time point, the expression levels of HSP60 and HSP90 in the gastric mucosa were significantly higher in females than those in males. An estrogen-treatment significantly induced the expression of HSP60, HSP70 and HSP90 in the gastric mucosa. Inversely, an ovariectomy dramatically reduced the expression of HSP60, HSP70 and HSP90 in the gastric mucosa. Our results suggested that estrogen might play an important role in gastric mucosal protection with the induction of gastric mucosal HSPs

Performance of large area Micro Pixel Chamber

A novel gaseous two-dimensional imaging detector "Micro Pixel Chamber (micro-PIC)" has been developed. This detector is based on double sided printed circuit board (PCB). We have developed large area (10cm x 10cm) micro-PICs with 65536 pixel anodes of 400um pitch on a 100um thick insulating substrate. Achieved energy resolution was 30% (FWHM) at 5.9keV, and a gas gain of 7000 was obtained with argon ethane (8:2) gas mixture. This gain is high enough to detect minimum ionizing particles with such a small electrode pitch. Although several discharges occurred during 65 hours continuous operation, the detectors have kept stable operation with high gain. The micro-PIC is a useful detector for many applications e.g. X-ray, gamma ray, and charged particle imaging. The micro electrode structure allows us to measure directions of primary electrons due to incident X-rays or gamma rays, which provide a strong method for X-ray polarimetry and gamma-ray imaging.Comment: 4 pages, 8 figures, to appear in the proceedings of 6th International Conference on Position Sensitive Detectors, 9-13 Sep 2002, Leicester, UK (Nucl. Instr. and Meth. A

Purpose, use, and preparation of clinical practice guidelines for the management of biliary tract and ampullary carcinomas

Apart from periampullary carcinoma, the prognosis of biliary tract carcinomas, including hilar cholangiocarcinoma, extrahepatic biliary tract carcinoma, and gallbladder carcinoma, remains poor. Sophisticated diagnostic skills and treatment methods and their application are naturally required to achieve better treatment results for biliary tract carcinomas. However, it is not too much to say that, due to the paucity of high-level evidence for the management of these carcinomas, medical care by healthcare providers in clinics and at medical institutes throughout the world is currently delivered without common consensus and common standards. The clinical practice guidelines for the management of biliary carcinoma outlined here were produced with the aim that they could be used by physicians involved in the care of biliary tract carcinomas, as indicators that could help them provide their patients with the most appropriate care possible at this time. Also, the guidelines were prepared to provide measures that could assure patients with biliary tract carcinomas of safe medical care. The present guidelines are characterized by their clarification of clinical questions assumed to be often shared by healthcare professionals. For clarity, we divided the contents of the guidelines into eight areas. In each area, clinical questions are presented, together with recommendations of clinical actions in response to the question. As mentioned already, there is a paucity of high-level evidence in this area; therefore, the recommendations are classified into grades, of which there are five: A, strongly recommend performing the clinical action; B, recommend performing the clinical action; C1, the clinical action may be useful, although there is a lack of high-level scientific evidence; C2, clinical action not definitively recommended ecause of insufficient scientific evidence; D, recommend not performing the clinical action. The grading of the recommendations is based on the determination of the level of evidence in references on which the recommendation is based