Water level monitoring after shutdown using neutron and gamma flux measurements in PWR

The improvement of the vessel water assessment of a PWR during normal operation and in abnormal conditions (e.g. accidental situations) is an important issue for the safety of nuclear power plants. The neutron and gamma flux and spectra in the ex-core region and at shutdown conditions were studied with the objective to investigate whether their intensities are sufficient and spectral forms suitable to provide meaningful information about the coolant density and/or coolant level in the reactor. The results are somewhat less encouraging and the possibilities more restricted than expected at the beginning. Some of the methods considered had to be discarded, but at least one option has been identified as being very promising