Patent Number: 
Section: claims

1. A probe system for detecting a coolant level and flow velocity in a nuclear reactor, in combination, comprises a conductivity probe; and a time-domain reflectometer probe, wherein the probe system is at least partially arranged in a downcomer of the nuclear reactor. 2. A boiling water reactor, comprising:a reactor pressure vessel;a core shroud arranged concentrically inside the reactor pressure vessel to provide an annular downcomer forming a coolant flow path between a wall of the reactor pressure vessel and the core shroud; andsystem as recited in claim 1 for determining one of a coolant level and a flow velocity within the reactor. 3. The reactor according to claim 2, wherein the conductivity probe comprises one of an electrical conductivity (EC) probe and a thermal conductivity (TC) probe. 4. The reactor according to claim 2, wherein the probe system is at least partially arranged within the downcomer of the reactor for determining the coolant level and the flow velocity within the downcomer of the reactor. 5. The reactor according to claim 2, wherein the boiling water reactor is a natural circulation boiling water reactor. 6. The probe system according to claim 1, wherein the conductivity probe comprises one of an electrical conductivity (EC) probe and a thermal conductivity (TC) probe. 7. The probe system according to claim 1, wherein the nuclear reactor comprises a boiling water nuclear reactor. 8. The probe system according to claim 7, wherein the boiling water nuclear reactor comprises a natural circulation boiling water reactor.