NEUTRON POISON TANK FOR ATWS HOUSED IN NUCLEAR REACTOR PRESSURE VESSEL

摘要

PURPOSE: To improve such a boiling water reactor as the core is contained in a rector pressure vessel and an upper steam dome coupled with the steam outlet of pressure vessel is installed in the pressure vessel. CONSTITUTION: A container 16 containing a neutron poison 20 effective for inactivating a core is installed in an upper steam dome 18. The container 16 communicates with the upper steam dome is order to pressurize the neutron poison 20 contained therein. The container 16 is also coupled with a duct 32 extending below the core and the duct 32 includes a valve 30 operable to discharge the neutron poison 20 through the duct 32. When the neutron poison 20 is discharged, the neutron poison 20 flows down gravitationally below the core through the duct and then it is mixed with the cooling water of reactor flowing through the core thus achieving inactivation of the core.