Patent Number: 
Section: claims

1. A method of decontaminating a boiling water reactor comprising at least one recirculation loop having a plurality of recirculation pipes piped in parallel with each other hydraulically connected with a reactor pressure vessel, comprising the steps of: installing plugs on each of two outlets of a jet pump ram""s head manifold connected with a riser pipe extending from a reactor pressure vessel nozzle connected with one of the recirculation pipes in the recirculation loop;  introducing a monitoring gas into the ram""s head manifold through one of the plugs installed therein for monitoring the pressure in the manifold connected with the riser pipe; and  determining the level of a decontamination solution in the recirculation loop from the pressure of the monitoring gas in the manifold connected with the riser pipe. 2. The method of decontaminating a boiling water reactor of  claim 1 , including the step of: pumping the decontamination solution in the riser pipe while the monitoring gas is introduced into the ram""s head manifold. claim 1 3. The method of decontaminating a boiling water reactor of  claim 1 , including the step of: pumping the decontamination solution into or out of the riser pipe while the monitoring gas is introduced into the ram""s head manifold. claim 1 4. The method of decontaminating a boiling water reactor of  claim 1 , including the step of: sloshing the decontamination solution in the riser pipe while the monitoring gas is introduced into the ram""s head manifold. claim 1 5. The method of decontaminating a boiling water reactor of  claim 1 , wherein the reactor has two recirculation loops, including the step of: pumping the decontamination solution from one of the two loops to the other of the two loops while the monitoring gas is introduced into the ram""s head manifold. claim 1 6. The method of decontaminating a boiling water reactor of  claim 5 , wherein the step of pumping the decontamination solution from one of the two loops to the other of the two loops comprises the step of: recirculating the decontamination solution while the monitoring gas is introduced into the ram""s head manifold. claim 5 7. The method of decontaminating a boiling water reactor of  claim 1 , wherein the step of determining the level of the decontamination solution in the loop based upon the pressure of the monitoring gas in the ram""s head manifold comprises the step of: determining a differential pressure of a head of decontamination solution in the loop. claim 1 8. The method of decontaminating a boiling water reactor of  claim 1 , including the step of: venting the monitoring gas from the ram""s head manifold through one of the plugs installed therein. claim 1 9. The method of decontaminating a boiling water reactor of  claim 8 , wherein the monitoring gas is vented by the step of: venting the gas through one plug in the manifold and the gas is introduced into the manifold through the other plug. claim 8 10. The method of decontaminating a boiling water reactor of  claim 8 , including the step of: pulling a vacuum on the manifold to remove water from the manifold. claim 8 11. The method of decontaminating a boiling water reactor of  claim 1 , including the further steps of: claim 1 installing a plug in a reactor vessel nozzle connected with a suction pipe extending to a suction connection of a recirculation pump in the recirculation loop;  introducing a monitoring gas through the plug in the suction pipe extending to the suction connection of the recirculation pump for monitoring the pressure in the suction pipe connected with the suction connection of the recirculation pump; and  determining the level of the decontamination solution in the suction pipe extending to the suction connection of the recirculation pump from the pressure the monitoring gas introduced through the plug in the reactor vessel nozzle into the suction pipe extending to the suction connection of the recirculation pump.