Presentation of the Characterization of High Enriched Pu Rods (CHIPS) project

N. Nakae (*), M. Verwerft (**)

 

(*) JNES, Tokyu Reit Toranomon Bldg. 7F, 3-17-1, Toranomon, Minato-ku,
Tokyo 105-0001, Japan

(**) SCK•CEN, Boeretang, 200 B-2400 Mol, Belgium

 

Background

Several decades have passed since Japan's first commercial nuclear power plant (NPP) began operation in Ibaraki Prefecture in 1966. As of December 2007, Japan has fifty-five reactors operating with a total output of 49 500 megawatts electric (MWe). Nuclear power accounts for approximately one-third of the Japan's total electric power output. Part of Japan's nuclear policy is to implement the Mixed Oxide (MOX) utilization program; that is, to use MOX fuel in conventional light water reactors (LWRs). The Japanese electric utilities are aiming to implement the utilization of plutonium in 16 and 18 light water reactors by the Fiscal Year 2010 (the "Pluthermal Program"). The interest to use MOX fuel is to maintain in the long run Japan's energy sources and to reduce the plutonium stockpiles.

The Belgian MOX experience goes back as early as 1963, with the loading of twelve MOX fuel rods in its pioneer PWR (the BR-3 reactor at Mol). Since then, SCK•CEN and her daughter company BELGONUCLEAIRE S.A. have continued MOX fuel research and development, with as result the MIMAS production process that is today the production technology applied for 95% of the total produced MOX for NPP application. BELGONUCLEAIRE S.A. started industrial scale MOX production since 1986 and has produced more than 600 tons of MOX, for 21 NPP’s worldwide. MOX fuel has been successfully introduced in the Belgian NPP's DOEL-3 and TIHANGE-2 (MOX loading authorised in 1994 and implemented since 1995). The Materials Test Reactor (BR-2) and the research laboratories of SCK•CEN are licensed and equipped to handle MOX fuels and have been involved in the vast majority of all international MOX research projects.

 

Project CHIPS

The purpose of the project on the "Characterization of High Enriched Pu Rods", also called "CHIPS" is to clarify the irradiation behaviour including physical property change on MOX fuel having high plutonium content under high burnup condition and to obtain the technical data for safety regulation and/or licensing in Japan. The project started in JFY 2007 and will continue until JFY 2011. JNES sponsors the CHIPS Programme, which is carried out by SCK•CEN and shall make use of the SCK•CEN facilities at Mol, Belgium.

In the last BR-3 cycle (July 1986 to July 1987), MOX fuel rods from a fabrication lot enriched to 14% (Pu/(U+Pu)) were loaded. A subset of these rods was further irradiated in the CALLISTO loop of the BR-2 reactor between 1997 and 2001. The CALLISTO loop simulates the conditions of a PWR (temperature, pressure, water chemistry, neutron flux and spectrum). For the CHIPS project, three rods were selected for a detailed characterisation, post-irradiation examinations and further irradiation extension.

Organisations involved

·         The Japan Nuclear Energy Safety Organization (JNES) has the mission to establish the base to ensure the nuclear safety in nuclear utilization for energy. One of the procedures to do so is gathering the required technical data and knowledge.
The Safety Standard Division of JNES has many responsibilities, and one of them is investigating the characteristics of irradiated MOX fuel.

·         The Studiecentrum voor Kernenergie/Centre d’Etude de l’Energie Nucléaire (SCK•CEN) is a Foundation of Public Utility. SCK•CEN was created in 1952 in order to give the Belgian academic and industrial world access to the worldwide development of nuclear energy. SCK•CEN contributes to nuclear safety and radiation protection; medical and industrial applications of radiation and the backend of the nuclear fuel cycle.