US 6,795,518 B1 · Integral PWR with diverse emergency cooling and method of operating same

Abstract

Passive emergency cooling in response to a loss of coolant accident (LOCA) in a PWR, having an integral reactor pressure vessel incorporating the steam generators and housed in a small high pressure containment vessel, is provided by circulating cooling water through the steam generators and heat exchangers in an external tank to cool the reactor vessel at a rate sufficient to lower the pressure in the reactor vessel below that in containment to reverse mass flow out of the reactor vessel and keep the reactor core covered without the addition of makeup water. Suppression tanks inside the small high pressure containment structure limit peak blowdown pressure in containment and provide flood-up water and gravity fed makeup water to cool the core. Diverse cooling is provided by natural circulation of air, and if needed, water, over the spherical containment structure.

Claims15

Dependent claims

A method of operating a pressurized water reactor having a containment structure containing an integral reactor comprising at least one steam generator mounted together with a reactor core in a pool of reactor coolant in a reactor pressure vessel and with the at least one steam generator having a secondary loop extending outside of the containment structure, the method comprising:

in response to a loss coolant accident resulting in a mass flow of reactor coolant out of the reactor pressure vessel into the containment structure, circulating cooling fluid through the secondary circuit of the at least one steam generator to withdraw heat from the reactor pressure vessel and thereby condense steam within the reactor pressure vessel;
and
extracting the heat from the cooling water outside of the containment structure at a rate which, within no more than about 3 hours, condenses sufficient steam in the reactor pressure vessel to lower pressure in the reactor pressure vessel to a pressure at or below pressure in the containment structure resulting from the loss of coolant accident and thereby stopping or reversing the mass flow of reactor coolant from the reactor pressure vessel whereby the reactor core remains covered without the addition of water from other sources to the reactor pressure vessel.

A method of operating a pressurized water reactor having a containment structure filled with an incondensable gas and containing an integral reactor comprising at least one steam generator mounted together with a reactor core in a pool of reactor coolant in a reactor pressure vessel, the method comprising:

disposing a lower portion of the reactor pressure vessel containing the reactor core in a flood-up cavity in the containment structure;
including at least one suppression tank containing water in the containment structure;
and
in response to a loss of coolant accident, introducing the incondensable gas in the containment structure together with steam in the containment structure resulting from the loss of coolant accident into the water in the at least one suppression tank to condense the steam and compress the incondensable gas;
and selectively transferring water from the suppression tank to the flood-up cavity by reducing pressure in the reactor pressure vessel by removing heat directly from the reactor pressure vessel to outside the containment structure thereby lowering pressure in the containment structure and allowing the compressed incondensable gas in the suppression tank to push water from the suppression tank into the flood-up cavity.

2 more elements

Dependencies are inferred from the claim text.

Integral PWR with diverse emergency cooling and method of operating same

Life of this patent

Integral PWR with diverse emergency cooling and method of operating same

Life of this patent

Abstract

Claims15