[en] In response to an inquiry on the title issue received on Jun. 17, 1988, the Nuclear Safety Commission made a study and submitted the findings to the Prime Minister on Jul. 21, 1988. The study was intended to determine the conformity of the permission to the applicable criteria specified in laws relating to control of nuclear material, nuclear fuel and nuclear reactor. The proposed modification plan included changes in the facilities in the No.1 processing building and changes in processing methods which were required to perform processing of blanket fuel assemblies for fast breeder reactor. It also included changes in the facilities in the No.2 building which were required to improve the processes. The safety study covered the anti-earthquake performance, fire/explosion prevention, criticality control, containment performance, radioactive waste disposal, and other major safety issues. Other investigations included exposure dose evaluation and accident analysis. Study results were examined on the basis of the Basic Guidelines for Nuclear Fuel Facilities Safety Review and the Uranium Processing Safety Review Guidelines. It was concluded that the modifications would not have adverse effect on the safety of the facilities. (Nogami, K.)

[en] This report, compiled by the Nuclear Safety Commission to be submitted to the Prime Minister, shows results of examinations concerning a proposed change in the operation of processing nuclear fuel substances at the Tokai Plant of Atomic Fuel Industry Co., Ltd. From the examinations, it is concluded that part of the proposed change is appropriate with respect to the required technical capability and that part of the change can meet the safety requirements. For the proposed installation of combustion facilities, the following are confirmed: (1) earthquake-resistant considerations are properly incorporated in the design of the facilities, (2) the effects of combustion gas on the environment will be ignorable, (3) the waste treatment building which will contain the facilities is of appropriate fireproof construction and (4) the building will be managed properly. It is also confirmed that the safety will be maintained if the proposed change is made in the maximum capacity of the raw material storage facilities. Other examinations cover the proposed change in the capacity for the storage of radioactive wastes and the exposure risk for general people outside the facilities. (Nogami, K.)

[en] The Nuclear Safty Commission sent the reply to the Minister of International Trade and Industry on October 4, 1984, on this matter after having received the report from the Committee on Examination of Nuclear Reactor Safety and carried out the deliberation. It was judged that the applicant has the technical capability required for installing and operating these reactor facilities. Also it was judged that on the safety after these reactor plants are installed, there is no obstacle in the prevention of disaster due to contaminated substances and reactors. The policy of the investigation and deliberation is reported. The contents of the investigation and deliberation are the condition of location such as site, geological features and ground, earthquake, weather, hydraulic problem and social environments, the safety design of reactor facilities, the evaluation of radiation exposure dose in normal operation, the analysis of abnormal transient change in operation, accident analysis and the evaluation of location. (Kako, I.)

[en] In connection with the Three Mile Island nuclear power accident in March, 1979, in the United States, in order to introduce the lessons from it in the nuclear power safety regulations in Japan, 52 items to be reflected to the nuclear power safety measures were chosen by the Nuclear Safety Commission. Of these, 16 items were examined by the Committee on Examination of Reactor Safety. It was decided that these results would be introduced in the nuclear safety regulations, by the Nuclear Safety Commission. The following 16 items are described. For the examination, four items concerning the automatic operation of safety systems and others; for the design, five items concerning a small rupture accident, the monitoring of the state of primary coolant, control room layout and others; for the operation management, seven items concerning the inspection at the time of repair, the prevention of faulty handlings by operators and others. (J.P.N.)

[en] A report by the Nuclear Safety Commission to Prime Minister, concerning the alteration in the heavy water criticality experimental facility in the Oarai Engineering Center in PNC, was presented: the technical capability of PNC and the safety after the alteration were confirmed. The alteration is as follows. The fuel assemblies with 36 fuel rods and the grid plates with lattice interval of 24.2 cm are additionally introduced in the criticality facility. Nine fuel assemblies each with 36 rods are loaded in the middle of the reactor core, of which the one located at the center has five different fissile material contents. The examination made by the Committee on Examination of Reactor Safety, which confirmed the safety, is described on the structural design and nuclear design. (Mori, K.)

[en] The Nuclear Safety Commission on Dec. 19, 1987 directed the Nuclear Fuel Safety Expert Group to carry out a study on it, made deliberations after receiving a report from the Group on July 13, 1988, and submitted the findings to the Prime Minister on July 21. The study and deliberations were intended to determine the conformity of the permission to the applicable criteria specified in laws relating to control of nuclear material, nuclear fuel and nuclear reactor. The investigation on the location covered the site conditions, meteorology, ground conditions, hydrology, seismic environments, and social environment. The investigations on the safety design addressed the anti-earthquake performance, fire/explosion prevention, criticality control, thermal stability, containment performance, safety against natural phenomena other than earthquake, radioactive waste management, and radiation control. Other investigations included exposure evaluation and accident analysis. It was concluded that the permission would not have adverse effects on the safety of the processing business. (Nogami, K.)

[en] On this problem, about which the Nuclear Safety Commission instructed the Committee on Examination of Nuclear Fuel Safety to do investigation and deliberation on May 23, 1985, the Nuclear Safety Commission presented a report to the Prime Minister on September 5, 1985, after it had received the report from the Committee and carried out the deliberation. It was recognized that the technical capability of the applicant is appropriate. It was judged that the safety after this alteration of the processing facilities can be ensured. The main items of the investigation and deliberation were the aseismatic design and the countermeasures against fires and explosions of the additionally built and reconstructed parts of the processing factory, the criticality control of a single unit and plural units, waste treatment, the radiation control in the working environment, personal exposure and surrounding environment, the safety function of the important facilities, and the exposure dose of general public at the time of an accident. It was confirmed that there was not any problem in these points. (Kako, I.)

[en] The Nuclear Safety Commission reported to the Prime Minister on September 22, 1983, that as the result of deliberation referring to the guideline for examining the safety design of power reactor facilities, the safety after the alteration of the installation of these reactor facilities was judged to be ensured. It was confirmed that there would be no trouble regarding safety when unsteady operation and reactivity pulse operation would be stopped and only steady operation continued, and the pile oscillator facility would be removed accompanying it. Also the change of highest fuel temperature and highest surface temperature of cladding from 400 and 350 deg C to 300 and 250 deg C, respectively, are adequate. The change of maximum credible accident to the reactivity accident during raising reactor output does not change the result of accident evaluation heretofore. The change of continuous maximum thermal output from 2 kW to 100 W was confirmed to be harmless. (Kako, I.)

[en] The Nuclear Safety Commission submitted the report to the Science and Technology Agency on the basis of a report of the Subcommittee on Processing the Usage to the Committee on Examination of Nuclear Fuel Safety, concerning the safety of the alteration (new installation of a waste safety testing facility) in the Tokai Research Establishment, JAERI; and its safety was confirmed. The items examined by the Subcommittee were as follows: the aseismicity of buildings and facilities for the waste safety testing facility, keeping of negative pressure in the buildings and facilities, effects of the heating components of a vitrification unit and an alpha acceleration test unit, prevention of the explosion due to hydrogen generation in a test waste-liquid tank, fire prevention in the cell, effect of radioactive material on the surrounding environment in normal operation, evaluation of exposure dose in the surrounding environment in a hypothetical accident. (J.P.N.)

[en] A report by the Nuclear Safety Commission to the Ministry of International Trade and Industry, concerning the permission of the alteration in the fabrication business of nuclear fuel materials in the Tokai Works Japan Nuclear Fuel Conversion Co. was presented; The technical capability of Japan Nuclear Fuel Conversion Co. and the safety after the alteration were confirmed by the NSC. The examination made by the Committee on Examination of Nuclear Fuel Safety of the NSC for the safety after the alteration is described: the aseismatic design and the countermeasures to fire in the conversion testing building, criticality management, waste treatment, radiation control, the exposure dose of general people. (Mori, K.)