Development of experimental metal sphere-mass map of reactor vessel scale models



Soon-Woo Han Seong-Il Lee Jeong-Han Lee Jin-Ho Park


Loose parts in coolant systems of a nuclear power plant (NPP) can damage structural integrity of the systems and loose part signals monitoring systems (LPMS) are installed in most of NPPs. LPMS detect impact signal of a loose part and generate alarm if amplitude of the signal is over preset level. If impact signal detected, mass estimation of the loose part must be carried out in order to see the effect of the part impact on structural integrity. A metal sphere-mass map, which shows relations between amplitude and center frequency of impact signals according to mass, is essential in mass evaluation of a loose part and the map built for US NPPs has been used so far. For the purpose of precise impact analysis suitable for Korean NPPs, this work discusses the development of a mass map of Korean Standard Nuclear Power Plant (KSNP) based on experimental data for scale models of a KSNP reactor vessel as tests for real NPP vessels under operation is actually impossible. Impact tests were carried out for scale models by using metal sphere with various mass and velocity. Amplitudes and center frequencies of impact signals were investigated based on time-frequency analysis and the mass map for each models were constructed based on the results. Blind tests were additionally implemented with metal sphere with unknown mass and velocity and verified feasibility of the proposed metal sphere mass map.

Abstract 5 | PDF Downloads 12




Lee, J. H. & Park, J. H. (2016). Distance attenuation of bending wave to analyze the loose parts impact signal, Transactions of Korean Society of Noise and Vibration Engineering, Vol. 26(5), pp. 594-601.
Mayo, C. W. & Shugars, H. G. (1988). Loose part monitoring system improvements, Progress in Nuclear Energy, Vol. 21, pp. 505-513.
Olma, B. J. (1985). Source location and mass estimation in loose parts monitoring of LWR’s. Proceedings of 18th Informal Meeting on Reactor Noise, April 10-12, Prague, Czechoslovakia.
Park, J. H. & Kim, Y. H. (2006), Impact source localization on an elastic plate in a noisy environment, Measurement Science and Technology, pp. 2757-2766.
The American Society of Mechanical Engineers (2010), ASME OM-2009: Operation and Maintenance of Nuclear Power Plant - Part 12, ASME, New York, NY: ASME.
Tsunoda, T., Kato, T., Hirata, K., & Tsuneoka, O. (1985). Studies on the loose part evaluation technique, Progress in Nuclear Energy, Vol. 15, pp. 569-576.
Weiss, J. M., & Mayo, C. W. (1991). Recommendations for effective loose parts monitoring, Nuclear Engineering and Design, Vol. 129, pp. 121-127.
Special Session Papers