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Takahashi, Fumiaki; Shigemori, Yuji*; Seki, Akiyuki
Hozengaku, 8(1), p.56 - 61, 2009/04
Failure of safety management system can bring about a heavily exposed person in maintenance of a radiation facility, though such a case is very rare. A method using radiation transport code has advantages in an assessment of dose distribution inside a human body. Complicated procedures, however, are needed to prepare an input-file and to derive radiation dose based upon descriptions of an output-file in a numerical analysis using a radiation transport code. Thus, a system was developed to set up necessary information for an input file and to give radiation dose from an output file by a dialogue method using graphical user interfaces. Dose assessment can be effectively carried out for a radiological accident with this system.
Ueno, Fumiyoshi; Yamamoto, Masahiro; Kato, Chiaki
Hozengaku, 7(4), p.50 - 56, 2009/01
Corrosion of ultra-low carbon type 304 stainless steel in boiling nitric acid solution was analyzed by statistical approach. A large scale mock-up of an evaporator was introduced to perform corrosion test of heat exchanger tubes, and change in loss of wall thickness and intergranular penetration depths of the tubes during test duration was measured and analyzed statistically applying normal distribution and Gumbel distribution. As the results, it was considered that tube wall was corroded uniformly and maximum value of loss of thickness was not exceeded by maximum depth of intergranular penetration. This conclusion means that tube wall thickness measurement can be applied to prevention maintenance against corrosion with intergranular penetration of stainless steel in boiling nitric acid solution.
Fujishima, Tadatsune; Sakamoto, Naoki; Mizukoshi, Yasutaka; Amagai, Tomio; Omori, Tsuyoshi
Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.388 - 392, 2008/07
no abstracts in English
Sakamoto, Naoki; Yoshikawa, Katsunori; Kushida, Naoya; Nakamura, Yasuo; Sukegawa, Kiyoshi*
Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.226 - 230, 2008/07
no abstracts in English
Terunuma, Tomohiro; Ozeki, Tatsuya; Fukuari, Yoshihiro
Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.129 - 132, 2008/07
The two dissolvers installed in the Tokai reprocessing plant had failed occurred successively in 1982 and 1983. Then, remote-controlled equipment for repair and inspection has been developed because the dissolvers were installed under the high dose of radiation and cannot access easily. After repair of the dissolvers, the periodic inspection by remoteness is periodically carried out once per year for soundness confirmation of the vessels. Moreover, the remote inspection equipment for periodic inspection was developed, which time required for inspection is too short compared with former equipment.
Nio, Daisuke; Ota, Kazunori; Ishizaki, Katsuhiko
Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.393 - 395, 2008/07
The research reactor JRR-3 was constructed for the purpose of development of nuclear technology and a large scale modification was done. It is necessary to investigate a maintenance methods considering high aging, because more than 15 years has passed from a large modification. In such situation, we should continue condition monitoring method which does not spoil safety and reliability and apply other instruments. So far, monitoring of vibration and lubricating oil has been done, and we might think it appropriate. From now on, we continue investigating that condition monitoring could be applied for other instruments.
Yasuo, Kiyoshi; Seto, Nobuhiko; Watahiki, Seiichi; Fukuari, Yoshihiro
Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.385 - 387, 2008/07
The nitric acid solution including nuclear fuel material is transferred by the three way valve called VCV (VCV: vide-casse-vide in Fr.) using vacuum in the Tokai Reprocessing Plant. The reliability of initial three way valve was not obtained because failure occurred by use for one or two years. The cause of failure was damage of the plastic diaphragms in the moving parts. Then, the new three way valve with stainless-steel bellows was developed. there is no failure in moving parts, reliability improved significantly.
Tagawa, Akihiro; Ueda, Masashi; Miyahara, Shinya; Yamashita, Takuya
Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.470 - 472, 2008/07
This paper describes the development of a new sensor for the pipe health monitoring. The Hybrid measuring using EMAT was made as a trial. It examined and checked that it could measure. The result confirmed that the high accuracy of 200 
C at high temperature was acquired in pipe surface temperature, pipe wall thinning, and water temperature.
Takamine, Jun; Haruyama, Mitsuo; Takase, Misao
Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.481 - 484, 2008/07
We have not yet known the nondestructive detection method to determine each quantity of the object which Uranium and Plutonium is mixed in, such a waste generated from nuclear fuel cycle facility, and so radioactive intensity of Pu-239 is 10,000 times as much as U-235. Therefore, on radioactive assessment, it is important to precisely quantify each mass. Then we paid attention to the component of delayed and prompt neutron obtained by 14 MeV neutron direct interrogation method and so developed the new method to determine mass ratio between Uranium and Plutonium from those correlations.
Kobayashi, Tetsuya; Ichimura, Toshiyuki; Sato, Masayuki
Nihon Hozen Gakkai Dai-5-Kai Gakujutsu Koenkai Yoshishu, p.340 - 343, 2008/07
The maintenance evaluation for research reactors has been obligated in Japan from 2004 as for power reactors. JAEA (Japan Atomic Energy Agency) has started to evaluate the maintenance for own research reactors on 2004. In this paper, we report the present status of the maintenance for JRR-3 (Japanese Research Reactor No.3), as well as the linear evaluation methods used. It is found that a series of preventing maintenance task on equipment and building of the reactor is properly performed.
Kawashima, Kazuhito; Suzuki, Toshiyuki; Muramatsu, Yasuyuki; Taguchi, Yuji
no journal, ,
For the aging management of reactor pool in the Nuclear Safety Research Reactor (NSRR) of Japan Atomic Energy Agency (JAEA), the inspection of pool lining, which is made of Aluminum, was decided to be an important item. Therefore, we develop a device which is controlled remotely and measures the thickness of the pool lining by non-destructive method using ultrasonic wave.
Yokoyama, Kenji; Suzuki, Satoshi; Ezato, Koichiro; Seki, Yohji; Enoeda, Mikio; Akiba, Masato
no journal, ,
An infrared thermography NDE facility which is utilized in the acceptance test of ITER divertor components has been developed in JAEA. This NDE facility can inspect the integrity of the bonding interface of the divertor components based on its surface temperature response by means of switching of hot (95 C)/cold (5 C) water. The advantages of this facility are (1) to have active coolant purging system which enables rapid temperature change and (2) to inspect the surface and the both side walls of three components at a time. We have conduct test operation for the divertor mockups and have found sufficient performance to implement the required acceptance test of the ITER divertor components.
-ray streaming calculation method for radiation shieldingMatsuda, Norihiro; Sasamoto, Nobuo
no journal, ,
no abstracts in English
Ito, Hiroto; Katsuyama, Jinya; Tobita, Toru; Onizawa, Kunio
no journal, ,
A probabilistic fracture mechanics (PFM) analysis code PASCAL-SP, which evaluates failure probabilities at welded joints in piping where being susceptible to stress corrosion cracking (SCC), has been developed. This code is based on Monte Carlo simulation technique and Japanese code related to the SCC evaluation. Uncertainties and scatters of welding residual stress distribution were modeled using database obtained from parametric FEM analyses. Sensitivity analyses concerning uncertainties and scatters of welding residual stress distribution by PASCAL-SP were performed. It was shown that uncertainties and scatters of welding residual stress distribution largely affected failure probability and the failure probability increased with increasing the uncertainties and scatters.
Katsuyama, Jinya; Tobita, Toru; Ito, Hiroto; Onizawa, Kunio
no journal, ,
Stress corrosion cracking grows near the welding zone mainly due to high tensile residual stress by welding. The residual stress analysis due to welding of austenitic stainless piping is important and has been already conducted by many researchers. In present work, the effect of scatters of welding conditions such as heat input and welding speed on residual stress have been evaluated by parametric FEM analyses considering the variation of some parameters based on the welding experiments. The effects of welding conditions on crack growth behavior have been also evaluated by SCC growth simulations using calculated residual stress distributions and a procedure in the fitness-for-service code. Welding parameters such as heat input and welding speed have a strong influence on crack growth rate since residual stress is also affected by scatter of these welding parameters.
Tobita, Toru; Katsuyama, Jinya; Ito, Hiroto; Onizawa, Kunio
no journal, ,
Residual stress by welding would be one of the most significant factors in evaluating failure probabilities of PLR piping since the SCC growth behavior is strongly affected by residual stress distribution. The residual stress distribution is well known to change caused by varying of welding conditions. Therefore, to evaluate the scatter of welding condition and their influence on residual stress is important to assess the structural integrity of PLR piping. In present work, the scatters of welding conditions were evaluated by producing some series of butt-welding pipe specimens made of stainless steel. Residual stress distributions due to welding were measured by applying X-ray diffraction method and stress relief method. Measured welding conditions and residual stress distributions are provided to determine the conditions of welding residual stress simulations and to confirm an accuracy of the simulation described in the following paper.
Sakai, Katsumi; Tomita, Tsuneo; Shimizu, Kazuyuki
no journal, ,
The maintenance work of many equipments such as mechanical, electrical and instrumentations installed in Tokai Reprocessing Plant has been performed more then 10,000 times per year and about 90% of maintenances were preventive work. For the maintenance management, optimization of maintenance information is required. Therefore, the aim of construction of suitable maintenance management system, Tokai Reprocessing Plant Maintenance Support System(TORMASS) was developed from 1985 to 1992. About 24,000 equipments of specifications and about 261,000 maintenance detail were registered in this system. TORMASS has been used for the repair, inspection and replacement of equipment.
Inami, Shinichi; Okubo, Toshizumi; Domura, Kazuyuki
no journal, ,
no abstracts in English
Inami, Shinichi; Takeuchi, Kenji
no journal, ,
Rotation equipments such as blowers and pumps play an important role for securing safety at the Tokai Reprocessing Plant. The bearings in the rotation equipments are one of the important machine elements for stable driving. The most important control item for the bearings management is to maintain adequate lubrication any time. Oil slick thickness in the bearings can be quantitatively confirmed by the shock pulse method though it was difficult in the conventional vibration method used to confirm lubrication quantitatively. This method contributes to the leveling of the measurement technique in diagnosing the bearings.
Furusawa, Takayuki; Homma, Fumitaka; Inoi, Hiroyuki; Sawahata, Hiroaki; Nemoto, Takahiro; Watanabe, Shuji; Ota, Yukimaru
no journal, ,
Japan Atomic Energy Agency has constructed the HTTR (High Temperature engineering Test Reactor), which is the Japan's first High Temperature Gas-cooled Reactor (HTGR). The HTTR achieved the full power of 30MW and reactor outlet coolant temperature of 950C on April 19, 2004. Based on the HTTR maintenance experiences, the preservation technology for HTGR are developed. This paper describes its preservation philosophy and typical developed technologies.