Development of re instrumentation technology for irradiated fuel rod

The extension of burnup of LWR fuel is one of the current important issues from an economical point of view. The information on fission product (FP) gas release and center line temperature of fuel pellets during power transient are important to study pellet clad interaction (PCI) mechanism of LWR fuel rods. To study irradiation behavior of high burnup LWR fuel, re instrumentation of FP gas pressure gage and thermocouple for centerline temperature measurement to the fuel rod irradiated in LWR has been developed in the Department of JMTR. The most important technique was how to drill the center line of cracked pellets to insert a thermocouple. This problem being resolved, a thermocouple and FP gas pressure gage were dually instrumented to the fuel rod irradiated in LWR. Re instrumented fuel rod was loaded in the BOCA (BOiling water CApsule) to perform the demonstration test in the JMTR power ramping test facility. This paper describes the results of demonstration test as well as the development of the re instrumentation technologies