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Fukuda, Kodai; Yamane, Yuichi
Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 9 Pages, 2023/10
This study presents the results of multiphysics analysis, which investigates the change of reactivity caused by the motion of fluids, of Windscale Works criticality accident. The purpose of this study is to confirm previously reported trends of emulsion formation and increase in reactivity by the multi-physics analysis which takes the motion of fluids into account. Continuous energy Monte Carlo code MVP3 was used to calculate reactivity based on the material distribution obtained by CFD calculation using OpenFOAM. An interface program in python was developed to transfer data from OpenFOAM to MVP3. The change of reactivity caused by the motion of solutions was calculated without considering the generation of heat by fissions in a system that simulated the transfer vessel at Windscale Works. As a result, trends of emulsion formation and increase in reactivity were confirmed. The influence of the resolution of the calculation system on the results was also discussed.
Nagai, Haruyasu
Fission Product Behavior under Severe Accident, p.112 - 116, 2021/05
no abstracts in English
Yoshikawa, Shinji
JAEA-Technology 2019-024, 22 Pages, 2020/03
JAEA-Technology-2019-024.pdf:1.76MB
JAEA-Technology-2019-024-appendix(CD-ROM).zip:73.55MB
In various technical fields of nuclear energy, computer codes are often used for transient simulations of target phenomena. Some of the codes were developed many years ago and have been revised with newly acquired findings, rather than newly developed, because of many encompassed numerical models and complexity of algorithms. In many cases, available outputs for users are output text files and graphs showing temporal variations of parameters, despite diversified and huge number of output information items are posing difficulty to the users in grasping the whole picture of the reproduced phenomena. This report compiles a series of know-hows in building a post-processor software for large simulation codes which serves as an interactive tool for code users in understanding the reproduced consequence with visually understandable information items. These know-hows are acquired through post-processor developments for LWR severe accident simulation codes RELAP/SCDAPSIM and MELCOR.
Nakamura, Makoto; Tobita, Kenji; Someya, Yoji; Tanigawa, Hisashi; Gulden, W.*; Sakamoto, Yoshiteru; Araki, Takao*; Watanabe, Kazuhito*; Matsumiya, Hisato*; Ishii, Kyoko*; et al.
Plasma and Fusion Research (Internet), 9, p.1405139_1 - 1405139_11, 2014/10
Key aspects of the safety study of a water-cooled fusion DEMO reactor is reported. Safety requirements, dose target, DEMO plant model and confinement strategy of the safety study are briefly introduced. The internal hazard of a water-cooled DEMO, i.e. radioactive inventories, stored energies that can mobilize these inventories and accident initiators and scenarios, are evaluated. It is pointed out that the enthalpy in the first wall/blanket cooling loops, the decay heat and the energy potentially released by the Be-steam chemical reaction are of special concern for the water-cooled DEMO. An ex-vessel loss-of-coolant of the first wall/blanket cooling loop is also quantitatively analyzed. The integrity of the building against the ex-VV LOCA is discussed.
Yanagihara, Satoshi
Dekomisshoningu Giho, (28), p.2 - 9, 2003/10
Decommissioning of nuclear facilities has been actively progressed in the major member countries participating to OECD/NEA. The NEA has recognized necessity of studying various issues related to decommissioning nuclear facilities and it has made an approach to solve the issues from various ways. In the cooperative program for decommissioning (CPD), information on decommissioning projects has been exchanged among the member countries. In the working party on decommissioning and dismantling (WPDD), recent issues have been studied in terms of regulation, implementation of decommissioning projects and research and development on technologies. Decommissioning cost and regulatory practices were also studies and the reports were published, which will be useful for understanding the present issues on decommissioning in the world. The NEA's activity on decommissioning will be valuable for us to implement decommissioning projects in safe and economical manner in Japan. This report deals with the recent NEA activities on decommissioning.
JNC TN9400 2000-038, 98 Pages, 2000/04
JNC-TN9400-2000-038.pdf:7.49MB
As an effort in the feasibility study on commercialized Fast Breeder Reactor cycle systems, an evaluation of the measures to prevent the energetic re-criticality in sodium-cooled large MOX core, which is one of the candidates for the commercialized reactor, has been performed. The core disruptive accident analysis of Demonstration FBR showed that the fuel compaction of the molten fuel by radial motion in a large molten core pool had a potential to drive the severe super-prompt re-criticality phenomena in ULOF sequence. ln order to prevent occurrence of the energetic re-criticality, a subassembly with an inner duct and the removal of a part of LAB are suggested based on CMR (Controlled Material Relocation) concept. The objective of this study is the comparison of the effectiveness of CMR among these measures by the analysis using SIMMER-III. The molten fuel in the subassembly with inner duct flows out faster than that from other measures. The subassembly with inner duct will work effectively in preventing energetic re-criticality. Though the molten fuel in the subassembly without a part of LAB flows out a little slower, it is still one of the promising measures. However, the UAB should be also removed from the same pin to prevent the fuel re-entries into the core region due to the pressurization by FCl below the core, unless it disturbs the core performance. The effect of the axial fuel length of the center pin to CMR behavior is small, compared to the effect of the existence of UAB.
Ose, Yasuo*; Takase, Kazuyuki; Akimoto, Hajime
JAERI-Research 99-075, p.95 - 0, 2000/01
JAERI-Research-99-075.pdf:4.62MB
no abstracts in English
*; Watanabe, Norio; Hirano, Masashi
JAERI-Data/Code 98-037, 193 Pages, 1998/11
JAERI-Data-Code-98-037.pdf:6.14MB
no abstracts in English
Lund
PNC TN3410 98-002, 34 Pages, 1998/01
A new and improved Graphical User Interface (GUI) to the Modular Accident Analysis Program for FUGEN (MAAP/FUGEN) has been developed and implemented at Fugen. The new user interface is a superset of the existing GUI to MAAP - the MAAP/FUGEN/GRAAPH - in the meaning that it contains all the features of the GRAAPH, but in addition offers a number of new features. The new interface, named MAAP-PICASSO is based on the Picasso-3 technology developed by Institutt for Energiteknikk/OECD Halden Reactor Project. The main difference between the MAAP-PICASSO and MAAP-FUGEN-GRAAPH GUIs is that the MAAP-PICASSO GUI is completely decoupled from the numerical simulator. This gives a far higher flexibility regarding enhancement of the GUI, connection to other, external software and user friendliness. It also includes techniques for presenting 2 byte character set - i.e. displaying text in Japanese characters. A special software has been developed for automatic extraction and reuse of the graphical plant information provided in MAAP/GRAPH into Picasso language. This software-has been demonstrated not only on the Fugen plant data, but also other Nuclear Power Plant picture definitions provided by Fauske Inc. The new GUI requires a minimal modification of the MAAP code itself However, these modification is only for parameter communication and is not intrusive to the numerical computations of MAAP itself. The GUI has been developed using modular and object-oriented programming techniques, which makes it relatively easy to extend and modify to fulfill present and future requirements from the users at Fugen, and makes it compatible with future versions of the MAAP code. MAAP-PICASSO is developed on and currently running only on HP UNIX workstations. However, a new NT-based version of Picasso-3 will be released from the Halden Project in February 1998. This will further enhance the applicability and usability of the MAAP-PICASSO GUI.
Akie, Hiroshi; Takano, Hideki; Anoda, Yoshinari; Muromura, Tadasumi
Proc. of Int. Conf. on Future Nuclear Systems (Global'97), 2, p.1136 - 1141, 1997/00
no abstracts in English
Asahi, Yoshiro; *
Nuclear Technology, 72, p.24 - 33, 1986/00
Times Cited Count：3 Percentile：40.89(Nuclear Science & Technology)no abstracts in English
; *; ; *; *
Proc.2nd Int.Topical Meeting on Nuclear Power Plant Thermal Hydraulics and Operatiions, p.6 - 49, 1986/00
no abstracts in English
; *; Watanabe, Norio; *
Nihon Genshiryoku Gakkai-Shi, 27(11), p.1035 - 1046, 1985/00
Times Cited Count：2 Percentile：37.51(Nuclear Science & Technology)no abstracts in English
;
JAERI-M 84-200, 115 Pages, 1984/11
no abstracts in English
*; *;
JAERI-M 83-081, 96 Pages, 1983/05
no abstracts in English
*; *;
JAERI-M 83-048, 120 Pages, 1983/03
no abstracts in English
JAERI-M 7963, 163 Pages, 1978/12
no abstracts in English
; ;
Journal of Nuclear Science and Technology, 14(1), p.12 - 21, 1977/01
Times Cited Count：4no abstracts in English
JAERI-M 5095, 110 Pages, 1973/02
no abstracts in English
Nishimura, Satoshi*; Satake, Masaaki*; Nishi, Yoshihisa*; Kaji, Yoshiyuki; Nemoto, Yoshiyuki
no journal, ,
After the accident in Fukushima-Daiichi Nuclear Power Plants in 2011, deployment of spray and substitutional water inlet systems for cooling the spent fuels are recommended as safety measures against spent fuel pool (SFP) accident. In this work, analyses on an hypothetical accident which occurred by simultaneous lost of cooling ability and leaking of cooling water in SFP were conducted by using the severe accident code MAAP. For the counter measure optimization, water inlet condition to avoid cladding rupture was investigated.
