Calculation of the ex-core neutron noise induced by individual fuel assembly vibrations in two PWR cores
Tóm tắt
Calculation of the neutron noise induced by fuel assembly vibrations in two pressurized water reactor (PWR) cores has been conducted to investigate the effect of cycle burnup on the properties of the ex-core detector noise. An extension of the method and the computational models of a previous work have been applied to two different PWR cores to examine a hypothesis that fuel assembly vibrations cause the corresponding peak in the auto power spectral density (APSD) increase during the cycle. Stochastic vibrations along a random two-dimensional trajectory of individual fuel assemblies were assumed to occur at different locations in the cores. Two models regarding the displacement amplitude of the vibrating assembly have been considered to determine the noise source. Then, the APSD of the ex-core detector noise was evaluated at three burnup steps. The results show that there is no monotonic tendency of the change in the APSD of ex-core detector; however, the increase in APSD occurs predominantly for peripheral assemblies. When assuming simultaneous vibrations of a number of fuel assemblies uniformly distributed over the core, the effect of the peripheral assemblies dominates the ex-core neutron noise. This behaviour was found similar in both cores.
Tài liệu tham khảo
Y. Fujita, H. Ozaki, Neutron noise monitoring of reactor core internal vibrations at PWRs in Japan. Prog. Nucl. Energy 9, 423–436 (1982). doi:10.1016/0149-1970(82)90065-8
F.J. Sweeney, J. March-Leuba, C.M. Smith, Contribution of fuel vibrations to ex-core neutron during the first and second fuel cycles of the Sequoyah-1 pressurized water reactor. Prog. Nucl. Energy 15, 183–290 (1985). doi:10.1016/0149-1970(85)90051-4
I. Pázsit, C. Montalvo-Martin, A. Hernandez-Solis, P. Bernitt Cartemo, H. Nylén, in Proceedings NPIC & HMIT 2010, Las Vegas, Nevada, Nov. 7 2010. Diagnostics of Core Barrel and Fuel Assemblyvibrations in the Ringhals PWRs, Sweden (American Nuclear Society, LaGrangePark, IL, 2010)
C. Demazière, CORE SIM: a multi-purpose neutronic tool for research and education. Ann. Nucl. Energy 38, 2698–2718 (2011). doi:10.1016/j.anucene.2011.06.010
J.C. Robinson, F. Shahrokhi, R.C. Kryter, Inference of core barrel motion from neutron noise spectral density. Oak Ridge National Laboratory, ORNL/NUREG/TM-100 (1977)
I. Pázsit, C. Montalvo-Martin, H. Nylén, T. Anderson, A. Hernandez-Solis, P. Bernitt Cartemo, Development in core barrel motion monitoring and applications to the Ringhals PWR units. Nucl. Sci. Eng. 182, 213–227 (2016). doi:10.13182/NSE15-14
H.N. Tran, I. Pázsit, H. Nylén, Investigation of the ex-core noise induced by fuel assembly vibrations in the Ringhals-3 PWR. Ann. Nucl. Energy 80, 434–446 (2015). doi:10.1016/j.anucene.2015.01.045
I. Pázsit, C. Demazière, in Handbook of Nuclear Engineering, vol. 3, chap. 2, ed. by D.G. Cacuci. Noise Techniques in Nuclear Systems. (Springer, Berlin, 2010), pp. 1629–1737. doi:10.1007/978-0-387-98149-9_14
I. Pázsit, O. Glöckler, On the neutron noise diagnostics of PWR control rod vibrations. II. Stochastic vibrations. Nucl. Sci. Eng. 88, 77 (1984). doi:10.13182/NSE84-4
F. Zylbersztejn, H.N. Tran, I. Pázsit, C. Demazière, H. Nylén, On the dependence of the noise amplitude on the correlation length of inlet temperature fluctuations in PWRs. Ann. Nucl. Energy 57, 134–141 (2013). doi:10.1016/j.anucene.2013.01.057
J.A. Thie, Core motion monitoring. Nucl. Technol. 45, 5–45 (1979)