Behavior of LWR fuels with additives under reactivity-initiated accident conditions

Mihara, Takeshi; Udagawa, Yutaka; Amaya, Masaki; Taniguchi, Yoshinori; Kakiuchi, Kazuo

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.544 - 550, 2019/09

Annual report of Nuclear Science Research Institute, JFY2013 & 2014

Nuclear Science Research Institute

JAEA-Review 2018-036, 216 Pages, 2019/03

JAEA-Review-2018-036.pdf:19.22MB

Nuclear Science Research Institute (NSRI) is composed of Planning and Coordination Office, Fukushima Project Team and six departments, namely Department of Operational Safety Administration, Department of Radiation Protection, Engineering Services Department, Department of Research Reactor and Tandem Accelerator, Department of Fukushima Technology Development and Department of Decommissioning and Waste Management, and each departments manage facilities and develop related technologies to achieve the "Middle-term Plan" successfully and effectively. In order to contribute the future research and development and to promote management business, this annual report summarizes information on the activities of NSRI of JFY 2013 and 2014 as well as the activity on research and development carried out by Nuclear Safety Research Center, Advanced Research Center, Nuclear Science and Engineering Center and Quantum Beam Science Center, and activity of Nuclear Human Resource Development Center, using facilities of NSRI.

Behavior of fuel with zirconium alloy cladding in reactivity-initiated accident and loss-of-coolant accident

Fuketa, Toyoshi*; Nagase, Fumihisa

Zirconium in the Nuclear Industry; 18th International Symposium (ASTM STP 1597), p.52 - 92, 2018/01

http://doi.org/10.1520/STP159720160090

Extensive research programs have been performed for more than two decades in JAEA and a better understanding has been developed for fuel behavior under accident conditions. The program is comprised of: RIA studies including pulse-irradiation experiments in the NSRR, cladding mechanical tests, and development and verification of a computer code RANNS; LOCA tests including integral thermal shock tests, oxidation rate measurements, and cladding mechanical tests; development and verification of a computer code FEMAXI-6, etc. Data and findings from the research programs provided technical basis directly and indirectly for regulatory criteria in Japan and other countries. This paper reviews and summarizes the major outcome from the research programs and identifies further research needs, as the acceptance technical paper for the Kroll Medal award of ASTM.

Behavior of high-burnup advanced LWR fuels under accident conditions

Amaya, Masaki; Udagawa, Yutaka; Narukawa, Takafumi; Mihara, Takeshi; Taniguchi, Yoshinori

Proceedings of Annual Topical Meeting on LWR Fuels with Enhanced Safety and Performance (TopFuel 2016) (USB Flash Drive), p.53 - 62, 2016/09

In order to evaluate adequacy of present safety criteria and safety margins in terms of advanced fuels and provide a database for future regulation on them, JAEA started an extensive research program called ALPS-II program, which has been sponsored by NRA, Japan. This program is primarily composed of tests simulating a RIA and a LOCA on the high-burnup advanced fuels irradiated in commercial PWR or BWR. Recently, the failure limits of the high-burnup advanced fuels under RIA conditions were investigated at NSRR, and post-test examinations on the fuel rods after the pulse irradiation tests are being performed. In terms of the simulated LOCA test, integral thermal shock tests and high temperature oxidation tests were carried out at RFEF, and the fracture limits, high temperature oxidation rate, etc. of the high-burnup advanced fuel cladding were investigated. This paper mainly describes some recent experimental results obtained in this program with respect to RIA and LOCA.

Assessment report of research and development on "Nuclear Safety Research" in FY2014 (Post- and pre-review report)

Kudo, Tamotsu; Onizawa, Kunio*; Nakamura, Takehiko

JAEA-Evaluation 2015-011, 209 Pages, 2015/11

JAEA-Evaluation-2015-011.pdf:10.36MB

Japan Atomic Energy Agency (JAEA) consulted an assessment committee, "Evaluation Committee of Research and Development (R&D) Activities for Nuclear Safety", for post- and pre-review assessment of R&D on nuclear safety research. In response to JAEA's request, the Committee assessed mainly the progress of the R&D project according to guidelines, which addressed the rationale behind the R&D project, the relevance of the project outcome and the efficiency of the project implementation during the period of the current and next plan. As a result, the Committee concluded that the progress of the R&D project is satisfactory. This report describes the results of evaluation by the Committee. In addition, the appendix of this report contains presentations used for the evaluation, and responses from JAEA on the comments from the member of the Committee.

Model development of light water reactor fuel analysis code RANNS for reactivity-initiated accident conditions

Udagawa, Yutaka; Suzuki, Motoe; Amaya, Masaki

JAEA-Data/Code 2014-025, 27 Pages, 2015/02

JAEA-Data-Code-2014-025.pdf:2.53MB

A light water reactor fuel analysis code RANNS has been developed to analyze thermal and mechanical behaviors of a single fuel rod in mainly reactivity-initiated accident (RIA) conditions. The recent model development for the RANNS code has been focused on improving predictability of stress, strain, and temperature inside a fuel rod during pellet cladding mechanical interaction (PCMI), which is one of the most important behaviors of high-burnup fuels under RIA conditions. This report provides descriptions of the models developed and/or validated recently via experimental analyses using the RANNS code on the RIA-simulating experiments conducted in the nuclear safety research reactor (NSRR): models for mechanical behaviors as relocation of fuel pellets, pellet yielding, pellet-cladding mechanical bonding, and PCMI failure limit of fuel cladding, and thermal behaviors as pellet-cladding gap conductance and heat transfer from fuel rod surface to coolant water.

Reevaluation of fuel enthalpy in NSRR test for high burnup fuels

Udagawa, Yutaka; Sugiyama, Tomoyuki; Amaya, Masaki

Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 8 Pages, 2014/10

Simulation of the fracture behavior of zircaloy-4 cladding under reactivity-initiated accident conditions with a damage mechanics model combined with fuel performance codes FEMAXI-7 and RANNS

Udagawa, Yutaka; Mihara, Takeshi; Sugiyama, Tomoyuki; Suzuki, Motoe; Amaya, Masaki

Journal of Nuclear Science and Technology, 51(2), p.208 - 219, 2014/02

AA2013-0436.pdf:3.87MB

https://doi.org/10.1080/00223131.2013.859106

Transient response of LWR fuels (RIA)

Fuketa, Toyoshi

Comprehensive Nuclear Materials, 2, p.579 - 593, 2012/02

https://doi.org/10.1016/B978-0-08-056033-5.00044-6

Failure mechanism of NbO doped PWR fuels under power transient

Yanagisawa, Kazuaki

JAEA-Review 2010-054, 109 Pages, 2010/11

JAEA-Review-2010-054.pdf:36.09MB

(1) The niobia doped PWR fuel (test specimen) did not fail below 260 cal/g defined as the failure threshold for RIA. (2) The fuel failure occurred by the cladding melt-brittle mechanism irrespective to the doping. (3) The test specimen caused a significant axial PCMI to the magnitude of 18%. (4)Above 276 cal/g, the test specimen restructured and formed the bonding, the small radial cracks, the metallic agglomeration and inclusion at the very narrow ring area. The grain size of the test specimen at the ring was reduced from original 31 to 10-21 microns. Meanwhile, undoped fuel grew the grain size from original 9 to 60 microns at the similar ring because of the recrystallization.