Abstract
The low frequency noise is a phenomenon observed in some PWR reactors causing an
influence on the normal operational behavior of the power plant. Fluctuations in the neutron
flux density, in the low frequency range up to 4Hz, generate noise in the neutron
instrumentation (in-core and ex-core neutron detectors) that could affect to the limitation and
protection system of the reactor core, even it can activate a scram signal due to high neutron
flux.
This activity is included as a complementary study of our ongoing efforts in the study of
the neutronic noise in the PWR reactor cores and their associated instrumentation. In this
project, a deep analysis of the behaviour of a PWR reactor core has been carried out when a set
of inlet thermal-hydraulic perturbations are applied.
A set of inlet mass flow perturbations have been simulated with the CTF/PARCSv2.7
coupled code, which provides 3D results in both termal-hydraulics and neutronics. The cross
sections have been obtained using the SIMTAB methodology and the signal of incore and
excore neutron detectors are directly extracted from PARCS through modifications
incorporated in the code.
