Visual inspection to monitor / detect boiling

A visual inspection camera system has been designed for high temperature and pressure environments allowing for the monitoring of boiling for Pressurized Water Reactor (PWR) conditions. Determining the critical heat flux of water and the conditions for transitioning to film boiling will allow for a reevaluation of the conservative safety parameters reactors are designed for under transient conditions. Two key facilities are used to test heat transfer between heater rods and water under transient conditions. The first is the Transient Test Reactor (TREAT) that allows for testing in irradiated environments. The second is an out-of-pile pulse system that allows for testing out of a radiation environment. The Idaho National Laboratory has both facilities. Currently, two different instruments will be used to detect critical heat flux and the duration of film boiling. The first is a boiling detector developed by the Idaho National Laboratory. The second is a high-speed camera system that is being developed by The University of Idaho. Both are designed to be used at high temperature and pressure conditions. The primary focus of this paper is to explain the design and development of the high-speed camera system for the initial out-of-pile testing guaranteeing the camera system will stand up 2500 psi and 300 C (the conditions for the test). The camera system will use a camera operating at 2000 frames per second to watch the onset of film boiling for a 0.5 to 5-second pulse width heat addition. The design incorporates a unique borescope setup that will allow the camera to view inside the test vehicles used for in and out of pile testing. A future report at the end of the summer of 2019 will present the baseline data of the out-of-pile testing.