Masahiko Warashina

374. 燃料集合体信頼性実証試験―BWR燃料集合体熱水力試験

Nuclear Power Engineering Corporation (NUPEC) has conducted a proving test for thermal-hydraulic performance of BWR fuel (high-burnup 8×8, 9×9) assemblies entrusted by the Ministry of Economy, Trade and Industry (NUPECTH-B Project). The high-burnup 8×8 fuel (average fuel assembly discharge burnup: about 39.5GWd/t), has been utilized from 1991. And the 9×9 fuel (average fuel assembly discharge burnup: about 45GWd/t), has started to be used since 1999. There are two types (A-type and B-type) of fuel design in 9×9 fuel assembly. Using an electrically heated test assembly which simulated a BWR fuel bundle on full scale, flow induced vibration,

Sloshing Suppression Method for a Rectangular Pool Using Immersed Blocks and Baffle Plates

There is a possibility that water in a spent fuel storage pool may overflow due to sloshing during long-period earthquakes. Therefore, this paper presents two sloshing suppression methods for a rectangular pool to reduce the volume of overflow water. Vibration tests were carried out to evaluate the volume of overflow water. The 1/20-scale model pool is used. First method is applying immersed blocks on the bottom of the rectangular pool. The volume of the water over the sidewall should be the maximum when the 1st sloshing mode is excited, and this behavior has significant influence on the volume of overflow water. The immersed blocks suppress the 1st sloshing mode, thereby reducing the over flow water. Vibration test were conducted by changing the following conditions: height of blocks, open area ratio, block position in the excitation direction, and number of opening sections. Changing of the natural frequencies and the amplification ratios are confirmed by the sinusoidal sweep test. In random wave excitation tests, the volume of overflow water from the pool with the best configuration blocks is lower than about 60% of that from the regular pool. Second method is applying horizontal baffle plates on the sidewall of rectangular pool. Horizontal baffle plate is a well-known sloshing suppression method. However, there is a little information about the relationship between installation condition of baffle plate and volume of overflow water Vibration test were conducted by changing the following conditions: installation height level, overhang length of baffle plate. In random wave excitation tests, the volume of overflow water from the pool with the best installation condition baffle plate is lower than 40% of that from the regular pool.Copyright

Vibration Isolation System to Reduce High Frequency Vibrations due to Airplane Crash

Electrical panels in Nuclear power plants are usually designed to be rigid enough to reduce seismic response. However, design dynamic loadings for nuclear power plant are not only seismic loadings. The airplane crash (APC) load is also important dynamic load for nuclear power plant equipments. If the electrical panels are rigid enough for seismic loadings, the higher-mode vibrations of local floors due to the airplane crash will excite resonant vibration of electrical devices inside electrical panels, and so, the panels could lose its electrical functions.In this study, a vibration isolation system is applied to the electrical panels in order to reduce high frequency vibrations. The system consists of vertical and horizontal isolation rubbers which support four corners of lower end of electrical panels. Using this system, acceleration responses of panels during high frequency excitation due to airplane crash and so on, are reduced less than floor response. However, the rocking mode vibration is excited during an earthquake, because of its predominant frequency. Therefore, in the vibration isolation design, it is important to consider coupled vibration of horizontal and vertical mode and set the natural frequencies in the range that avoids spectrum peaks of acceleration, peaks arising from both the impact vibration and the seismic wave. In this paper, the design method and the vibration test are presented.Copyright

BWR 9×9 Fuel Assembly Thermal-Hydraulic Tests: 2 — Hydraulic Vibration Test

Nuclear Power Engineering Corporation (NUPEC) conducted thermal-hydraulic projects for verification of thermal-hydraulic design reliability for BWR high-burnup 8×8 and 9×9 fuel assemblies, entrusted by the Ministry of Economy, Trade and Industry (METI). As a part of the NUPEC thermal-hydraulic projects, hydraulic vibration tests using full-scale test assemblies simulating 9×9 fuel assemblies were carried out to evaluate BWR fuel integrity. The test data were applied to development of a new correlation for the estimation of fuel rod vibration amplitude.Copyright