Performance Test of a Capsule Load Device and Fatigue Test using the Device

A fatigue capsule is one of the special capsules to investigate the fatigue characteristics of the nuclear materials in a research reactor, HANARO. In this report, the performance test of a periodic load device and the preliminary fatigue test by using the load device newly developed for a fatigue capsule was performed. In order to obtain the characteristics such as a realization of the periodic wave shape and a controllability of the wave shape including the amplitude, the holding time and the period of the pressure, a spring and rigid bar specimens were used. The basic performance of the load device was reconfirmed by a preliminary test by using a specimen of 2.0mm in diameter made of aluminum and stainless steel, and a size of the specimen and test conditions suitable for the in-pile fatigue test were also investigated. Based on the preliminary test results, the fatigue test for the STS 316L specimen with 1.8mm in diameter and 12.5mm in gage length was performed under the same conditions as the temperature(550 .deg. C) of the specimen during irradiation tests except for the gamma flux. The test was conducted in the range of pressure from 10 to 15 kgf/cm2 and the periodic load of 4 cycles per minute during 18.5 days, but the specimen kept the initial displacement without large variation. Thus, in order to show the fracture within one period(23 days) of the reactor, the pressure was increased from 14 to 19 kgf/cm2. Finally, the fracture of the specimen occurred at a total of 127,865 cycles (22 days), and the displacement was 2.63mm. These results will be used for a determination of the test conditions and a comparison of the in-pile fatigue test results