Basic technology development of advanced non-destructive detection / Measurement of nuclear material for nuclear security and nuclear nonproliferation

Seya, Michio; Naoi, Yosuke; Kobayashi, Naoki; Nakamura, Takahisa; Hajima, Ryoichi; Soyama, Kazuhiko; Kureta, Masatoshi; Nakamura, Hironobu; Harada, Hideo

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/01

The Integrated Support Center for Nuclear Non-proliferation and Nuclear Security (ISCN) of Japan Atomic Energy Agency (JAEA) has been conducting (based on collaborations with JAEA other centers) the following basic technology development programs of advanced non-destructive detection/measurement of nuclear material for nuclear security and nuclear non-proliferation. (1) The demonstration test of the Pu-NDA system for spent fuel assembly using PNAR and SINRD (JAEA/USDOE(LANL) collaboration, completed in JFY2013), (2) Basic development of NDA technologies using laser Compton scattered -rays (Demonstration of an intense mono-energetic -ray source), (3) Development of alternative to He-3 neutron detection technology, (4) Development of neutron resonance densitometry (JAEA/JRC collaboration)This paper introduces above programs.

Phase Change Predictions for Liquid Fuel in Contact with Steel Structure using the Heat Conduction Equation

Brear, D. J.

PNC TN9410 98-005, 53 Pages, 1998/01

PNC-TN9410-98-005.pdf:2.09MB

When liquid fuel makes contact with steel structure the liquid can freeze as a crust and the structure can melt at the surface. The melting and freezing processes that occur can influence the mode of fuel freezing and hence fuel relocation. Furthermore the temperature gradients established in the fuel and steel phases determine the rate at which heat is transferred from fuel to steel. In this memo the 1-D transient heat conduction equations are applied to the case of initially liquid UO brought into contact with solid steel using up-to-date materials properties. The solutions predict criteria for fuel crust formation and steel melting and provide a simple algorithm to determine the interface temperature when one or both of the materials is undergoing phase change. The predicted steel melting criterion is compared with available experimental results.

The Influence of Gd content on the properties of simulated fuel debris

Akashi, Masatoshi; Hirooka, Shun; Watanabe, Masashi; Komeno, Akira; Morimoto, Kyoichi

no journal, , 

Uranium oxide fuels containing GdO had been used to control fuel power in reactors of the Fukushima Daiichi Nuclear Power Plant where the severe accident occurred in 2011. JAEA has been evaluating physical properties of the molten fuel debris in the damaged core. However physical properties of the fuel debris containing Gd are not known, hence it is very difficult to select an appropriate debris removal method. Especially, it is important to know the distribution of Gd in the molten fuels for the evaluation of nuclear criticality safety during removal work. In this study, simulated samples of the molten fuel debris, which consisted of ZrO, UO and GdO, were prepared and their properties, which are density, crystal structure, thermal conductivity, thermal expansion and melting temperature, were investigated. This study includes results obtained under the research program entrusted to International Research Institute for Nuclear Decommissioning including Japan Atomic Energy Agency by Agency for Natural Resources and Energy, Ministry of Economy, Trade and Industry (METI) of Japan.

Study on nuclear material management for fuel debris

Miyaji, Noriko; Takada, Akira*; Iwafuchi, Junichi; Tomikawa, Hirofumi; Shiba, Tomooki; Okumura, Keisuke; Nagatani, Taketeru; Nauchi, Yasushi*

no journal, , 

Nuclear materials in fuel debris need to be properly managed in order to assure to the international and national communities that no nuclear materials have been diverted. In order to provide this assurance, specific measures appropriate to the characteristics of the fuel debris are required. There is experience at managing fuel debris in similar situations, as it was the case of the partial meltdown at the TMI-2 in the US. The nuclear material in the fuel debris retrieved from the reactor was quantified in order to fulfill domestic law requirements in the US. NDA, DA, and visual observation were applied to the residual fuel in the reactor. On that specific accident, IAEA safeguards were not applied because the USA is a nuclear weapon state and therefore this power plant was not inspected by the IAEA. Nuclear material accounting (NMA)is an important measure to manage nuclear materials for states under IAEA safeguards. In this presentation a report on NMA as a measure to manage fuel debris will be discussed.