Practical gamma-ray spectrometry

Yonezawa, Chushiro; Matsue, Hideaki; Miyamoto, Yutaka; Suzuki, Daisuke; Yasuda, Kenichiro; Inagawa, Jun; Saito, Yoko

Jitsuyo Gamma-sen Sokutei Handobukku, 366 Pages, 2002/06

no abstracts in English

Long-term durability test of acid recovery evaporators made of Ti-5% Ta aIloy and zirconium

; Fujisaku, Kazuhiko*; *; ; Koyama, Tomozo

JNC TN8410 2001-013, 255 Pages, 2001/05

JNC-TN8410-2001-013.pdf:24.24MB

Mock-ups of acid recovery evaporators which are made of Ti-5% Ta alloy and Zr were tested under inactive condition for forty thousands hours to improve a corrosion resistance of acid recovery evaporator in Tokai reprocessing plant (TRP). The mock-up unit was designed and produced referring to the specification of acid recovery evaporator in TRP and the evaporation performance of the mock-up was 1/27 of TRP. A long-term durability of both evaporators was demonstrated by results of operation data, evaporation performance and corrosion resistance. The mock-up unit did not suffer from any trouble during the running test and the operation data such as temperature, flow, concentrations of nitric acid and metal ions were fairly stable within standard condition. As for the corrosion resistance, cracks and local corrosion such as intergranular attack were not observed on both evaporators after the running test, and a corrosion of weld was not selective. The average corrosion rates at measuring points were less than 0.1mm/yr, respectively, however, thickness of the Ti-5% Ta alloy evaporator was slightly reduced at all points of vapor phase region. In addition, from the result by test coupon, it is found that both materials have low susceptibility to stress corrosion cracking in this environment. The destructive inspection showed that the mechanical properties of both materials were not degraded during the running test. Finally, the total running time of the mock-up unit is much more than a maximum running time of acid recovery evaporator made of stainless steel in TRP (nearly 15,000 hours). On the basis of the test results, an excellent durability of Ti-5% Ta alloy and Zr evaporators under was successfully demonstrated throughout the mock-up test from an engineering perspective.

Research on advanced system safety assessment procedures (III)

Suzuki, Kazuhiko*; *

JNC TJ8400 2000-052, 136 Pages, 2000/02

JNC-TJ8400-2000-052.pdf:4.16MB

Though HAZOP is recognized as the useful safety assessment method, it requires a labor-intensive and time-consuming process. So recently computer-aided HAZOP has been proposed. The research report in 1999 (PNC TJ1400 99-003) presented HAZOP system based on the plant component malfunctions basic models. By using this basic model, not only state malfunction of component but also the consequence to external circumstance can be assessed. G2, which is an excellent object-oriented developer tool in GUI (Graphical User Interface), was used as a tool for developing the system. By using the graphical editor in the system, the user can carry out HAZOP easily. The purpose of this research is to improve the ability of the HAZOP system to obtain a more detailed HAZOP results. HAZOP is carried out according to the fault propagation of component level and the one of plant level based on plant component malfunctions basic models. Furthermore, the HAZOP system which can do the cause and effect analysis in detail intended for the component which processes two or more materials is developed. It is possible to carry out HAZOP for various plants by newly adding material information to the knowledgebase. We have applied this system to the Nuclear Reprocessing Facilities to demonstrate the utilities of developing system.

None

; ; ; ; ; ;

JNC TN8520 99-002, 56 Pages, 1999/04

JNC-TN8520-99-002.pdf:4.31MB

None

World Wide Web for database of Japanese translation on international nuclear event scale reports

Watanabe, Norio; Hirano, Masashi

Nihon Genshiryoku Gakkai-Shi, 41(6), p.628 - 638, 1999/00

https://doi.org/10.3327/jaesj.41.628

no abstracts in English

Development of Phased Mission Analysis Program with Monte Carlo Method - Improvement of the variance reduction technique with biasing towards top event -

Yang Jin An*;

JNC TN9400 99-013, 89 Pages, 1998/12

JNC-TN9400-99-013.pdf:2.0MB

This report presents a variance reduction technique to estimate the reliability and availability of highly complex systems during phased mission time using the Monte Carlo simulation. In this study, we introduced the variance reduction technique with a concept of distance between the present system state and the cut set configurations. Using this technique, it becomes possible to bias the tansition from the operating states to the failed states of components towards the closest cut set. Therefore a component failure can drive the system towards a cut set configuration more effectively. JNC developed the PHAMMON (Phased Mission Analysis Program with Monte Carlo Method) code which involved the two kinds of variance reduction techniques : (1) forced transition, and (2)failure biasing. However, these techniques did not guarantee an effective reduction in variance. For further improvement, a variance reduction technique incorporating the distance concept was introduced to the PHAMMON code and the numerical calculation was carried out for the different design cases of decay heat removal system in a large fast breeder reactor. Our results indicate that the technique addition of this incorporating distance concept is an effective means of further reducing the variance.

Devdopment of an intellectual maintenance management system; Development of trouble detection and troubleshooting evaluation system

; Tani, Satoshi; Yoshikawa, Shinji

PNC TN9410 98-023, 29 Pages, 1998/03

PNC-TN9410-98-023.pdf:1.33MB

Many research activities are conducted to enhance cost performance and safety of nuclear power plants operation and maintenance. Concept of autonomous operating system to equal the role of operators and of maintenance personnel with artificial intelligence and autonomous robots has been developed. An intellectual maintenance management system has been developed to be equipped with decision making functions of maintenance personnel. The intellectual maintenance management system is in charge of maintenance function of an autonomous plant, which consists of plant-wide monitoring, evaluation of component integrity, and scheduling of maintenance activities. In other words, this system should be equipped with preventive maintenance and corrective maintenance functions those are currently loaded on personnel. In this report, we discussed condition monitoring maintenance in the preventive maintenance. We also reported a sensor validation system development for machinery condition monitoring and diagnosis. We adopted distributed and cooperative system construction technique, which is expected recently in applications to large-scale plants. This system has inter-agent communication function for signal transmission and reception among distributed physics models of machineries. The system has been constructed for water / steam system of the LMFBR power plant. The system has been validated to be capable of cooperative sensor validation by the distributed set of agents, with quantitative indication of sensor deviation based on a newly developed fuzzy algorithm with inter-agent cooperation. The derived reference parameter value from the inter-agent evaluations also stands for the alternative measurment to the malfunctioned sensor.

Tritium behavior in fusion reactor facilities and the environment, 3; Tritium behavior in fusion fuel systems

Yamanishi, Toshihiko; Nishikawa, Masabumi*; *

Purazuma, Kaku Yugo Gakkai-Shi, 73(12), p.1326 - 1332, 1997/12

https://ci.nii.ac.jp/naid/110003826816

no abstracts in English

Current status of accident sequence precursor program for operational events at nuclear power plants

Watanabe, Norio

Nihon Genshiryoku Gakkai-Shi, 38(4), p.252 - 261, 1996/00

https://doi.org/10.3327/jaesj.38.252

no abstracts in English

Level-1 PSA on large fast breeder reactor (II); Evaluation of PLOHS frequency with the water steam system with decay heat removal capability

Hioki, Kazumasa

PNC TN9410 94-188, 160 Pages, 1994/05

PNC-TN9410-94-188.pdf:8.75MB

The Systems Analysis Section has been performing a probabilistic Safety Assessment (PSA) on a large fast breeder reactor (FBR) since JFY 1992. The objective of the study is to apply the PSA method to a plant in a conceptual design stage, develop system models, perform quantitative analyses and systematic evaluation, supply valuable insights to enhance reliability and safety, and reflect them to the basic design. The plant analyzed is a 600MWe class large FBR designed by the Plant Engineering Section in the "Large FBR design study" that has been performed since JFY 1990. The failure probability of the Decay Heat Removal System (DHRS) can be reduced approximately two orders if the Water Steam System (WSS) can remove the decay heat for the first 24 hours. The frequency of PLOHS, however, is not reduced to less than one third because the WSS cannot be used for some initiating events and the PLOHS frequency is dominated by the failure probability of DHRS without the WSS. The failure probability of DHRS is dominated by the common cause failures (CCFs) of vanes, dampers and valves around the air-coolers in the Auxiliary Cooling System (ACS). Therefore it is most important to eliminate the CCFs. Assuming that the CCFs have been eliminated by diversifying the components, the frequencies of PLOHS were evaluated. An analysis has shown that if the WSS can remove the decay heat alone, the PLOHS frequency is reduced approximately two orders. In this case the PLOHS frequency is dominated by the failure probability of the DHRS right after the reactor shutdown. The most effective way to reduce the PLOHS frequency is to increasc the redundancy of the DHRS for the first few hours after reactor shutdown. It is known through the experience of preceding plants that the success criteria can be relaxed to one loop natural circulation instead of forced circulation in the best estimate evaluation. It was shown that under such condition, the PLOHS frequency can be as low as 10 ...