[en] The cylindrically symmetric hydrodynamic equations with source terms are solved for the quark-gluon plasma formed in the central collisions of ²³⁸U+²³⁸U at the relative incident energy √s = 30 GeV/A, 100 GeV/A and 540 GeV/A. The highly energetic state once obtained has a long lifetime, because the source region expands not only in the transverse direction to the collision axis but also in the time direction (≅several tens of times of the collsion time). However the large increase of the energy density deposited in the central region can not be expected in spite of the rapid increase on √s. (author)

[en] The advanced thermal prototype reactor ''Fugen'' is a heavy water-moderated, boiling light water-cooled power reactor with electric output of 165 MW, which has been developed since 1966 as a national project. The start-up test was begun in March, 1978, being scheduled for about one year, and in March, 1979, it passed the final pre-use inspection and began the full scale operation. In this paper, the result of the start-up test of Fugen is reported. From the experience of the start-up test of Fugen, the following matters are important for the execution of start-up test. 1) Exact testing plan and work schedule, 2) the organization to perform the test, 3) the rapid evaluation of test results and the reflection to next testing plan, and 4) the reflection of test results to rated operation, regular inspection and so on. In the testing plan, the core characteristics peculiar to Fugen, and the features of heavy water-helium system, control system and other equipment were added to the contents of the start-up test of BWRs. The items of the start-up test were reactor physics test, plant equipment performance test, plant dynamic characteristic test, chemical and radiation measurement, and combined test. The organization to perform the start-up test, and the progress and the results of the test are reported. (Kako, I.)

[en] Of the start-up tests of ''Fugen'', the specific items are reported in the plant equipemt performance test, plant dynamic characteristic test, chemical and radiation measuring test, overall test, and start-up test. In the plant equipment performance test, 19 items were tested under nuclear heating condition and in loaded state, and it was confirmed that the results satisfied the design performance. In the plant dynamic characteristic test, 13 items were tested under power output condition, and it was confirmed that the results satisfied the design performance. The test is roughly classified into the control characteristic test of the plant control system, transient characteristic test in operation, and transient characteristic test at the time of tripping following a plant failure. Radiochemical and radiation level measuring tests were carried out to obtain the basic data for chemical and radiation management required for smooth plant operation, under atmospheric pressure, nuclear heating and power output conditions. Next, in the final loading test a 100 % electrical output, reactor-related data of about 200 points, turbine-related data of about 70 points and generator-related data of about 70 points were measured and evaluated to ensure that the plant can be safely and continuously operated. Finally, the start-up test program, implementing organization and testing process, the inspection prior to the operation, analytical prediction and data processing, independent inspection and the investigation items during stratup test are described. (Wakatsuki, Y.)

[en] In Oarai Engineering Center of Japan Nuclear Cycle Development Institute, decommissioning of nuclear facilities will be expected in future. The results of preceding JPDR decommissioning were researched and the radiation control in decommissioning was examined. The principles and technology necessary for radiation control in decommissioning were arranged. The radiation control in decommissioning seems to be on extension line of daily radiological work control. Noticing points are the control of exposure dose with disassembly of high radiological equipment, the surface contamination measurement of building disassembly waste which large arises and the radioactivity measurement of activated material. When high radiological equipment is disassembled, the measures which reduce the exposure in the remote manipulation are taken. The total radiation protection program including the control of exposure dose in preparedness stage must be decided. Much time and personnel are required, when surface contamination of waste arisen in the building disassembly was measured by surveymeters. Therefore, it is necessary to rationalize the measurement using automatic inspection equipment with large detection area. This type equipment has results which effectively fulfilled the function in the decommissioning of JPDR. It is possible to product the equipment in the combination of existing technology. (author)

[en] The energy density, the baryon number density and the velocity of fluid in the target fragmentation region in A + A collisions at √ s > 30 GeV/A are calculated by solving Kajantie's hydrodynamic equation in 1 + 1 dimensions in the laboratory system and it is shown that the mesonic matter created in the rear of the target fragmentation region flows backwards. (author)

[en] Since the establishment of a fast reactor, JOYO, in April 1977, ten periodical check-up tests have been performed. In this article, radiation control and characteristics of exposure status are discussed in view of the outcome of radiation control at the JOYO Reactor. The current techniques involved in radiation control do not pose any basic problems. The whole facility can be kept clean due to its structure. Major exposure sources at the fast reactor are radioactive corrosion products, like the case of a light water reactor. Activated sodium products, which are characteristic to a fast reactor, have scarcely contributed to radiation exposure. Major radiation exposures at the JOYO Reactor focus upon three specified controlled areas (area below the floor level of container, area of fuel washing installation, and area of waste disposal installation). Countermeasures for reducing exposures associated with the transportation process of corrosion products are the important themes to be considered. Considering the exposure form and developmental status of techniques for reducing exposures, sufficient low-level radioactivity could be achieved at the JOYO Reactor. (N.K.)

[en] For the purpose of the improvement in radiation measurement technique for radiation protection, new-type instruments using plastic scintillation fibers (PSFs) have been developed. PSFs are available for beta-rays and gamma-rays detection. The main achievement is a high sensitivity radioactive gas monitor and a dose-rate distribution measuring system. 1. The high sensitivity radioactive gas monitor. Because PSFs can cover the inner surface of a gas container, the radioactive gas monitor with wide detection area can be realized. Therefore, the monitor has a unique feature in high radiation detection efficiency. Since PSFs transmit scintillation light intensively, it is possible to use photomultiplier tube (PMT) with smaller photoelectric surface, that is to say, smaller thermal noise. Computational simulation and tests of trial manufactures were carried out to optimize the specifications, such as shape and size of a gas container. The detection limit of the prototype monitor was 5.4 x 10 ^-4 Bq/cm³ (for ⁸⁵Kr). The developed monitor is currently used as a practical exhaust gas monitor in an accelerator facility. 2. The dose-rate distribution measuring system. Two PMTs are installed at both ends of a PSF. The position of scintillation light emission in the PSF is analyzed with time-of-flight method. The distribution of scintillation light emission indicates that of radiation which incident in PSF. The system is available for measuring dose-rate distribution in wide area by one detector at once. As a result of the calibration under conventional way, the range of dose rate measurement was about 1 x 10^-6Sv/h to 1Sv/h. Since light transmitted in PSF attenuates immediately, there is a limit at the length of PSF used for the system. As a result of the test using various length PSFs, it was proven that the limit length was about 10 m. As a result of the application of collimated radiation, the position resolution of dose-rate distribution was several decade centimeters full width at half maximum (FWHM). Because of the characteristic of the position resolution, the measurement result at partially projected dose-rate distribution area is obtained as the distribution with particular FWHM. However, it was proven that original distribution was obtained by the unfolding calculation using the response function of the PSF. Dose-rate distribution was actually measured in a nuclear facility. The result was compared with that of using conventional detectors. The measuring accuracy each method was almost equivalent. The system achieved better operational performance and the availability of quickly distribution imaging was excellent. 3. The developing instruments. The surface contamination survey meter with wide detection area and the surface dose-rate monitor for radioactive waste carton boxes are under development. (author)

[en] Elastase (Elaszym 6T) was administered, in addition to the dietary instruction, to three patients with fatty liver. CT scanning revealed marked improvement in fatty liver. Transaminase levels returned to normal, total cholesterol levels tended to decrease, and HDL-cholesterol levels tended to increase. These results suggest that elastase is effective in the treatment of fatty liver. (Namekawa, K.)

[en] In order to monitor whether there exist unexpected effluence of radioactive gases at working places and waste gas systems in nuclear facilities, a gas-flow type ionization chamber is often used for measuring concentration of radioactive gas. However the ionization efficiency must be known to evaluate concentration of gas from measured ionization current. This paper presents the calculation of ionization efficiency by using EGS4 code for a cylindrical chamber. The results calculated were in good agreement with those obtained by experiments. Furthermore it became possible to evaluate ionization efficiency for radioactive gases with short half lives, which were hard to obtain by experiments. (author)

[en] A method of measuring the impurities of nuclear material samples using a pyrochemical multiple counter has been developed by Langner and others. The pyrochemical multiple counter consists of many thermal neutron detecting tubes arranged in four concentric rings within a polyethylene moderator, and a nuclear material sample is set in the center of the counter. Each ring of tubes has a different energy response owing to the difference of the effective moderator thickness, and each ring gives a different count with the same sample. The stopping power of the moderator varies with the incident neutron energy, and the differences in the counts from the various rings are related to the energy. The average energy of neutrons from a nuclear material sample varies with the impurities of the sample, therefore it is expected that the ratios of counts from the four rings will indicate the impurity concentration of the sample, and this was confirmed by experimentation. Langner and others used a multiple counter, but this method can be applied to two detectors which possess different energy responses and are in the same condition. In this paper, which investigates the applicability of this method to a fast-thermal neutron simultaneous counting detector which possesses two kinds of energy response in a single detector, we present the results of an experimental examination of the energy response of this detector to neutrons at energy of several MeV (J.P.N.)