ONE BODY HEAD ASSEMBLY OF REACTOR PRESSURE VESSEL, ONE BODY HEAD ASSEMBLY UNIT OF REACTOR VESSEL AND COOLING METHOD FOR CONTROL ROD DRIVE MECHANISM IN THE ONE BODY HEAD ASSEMBLY UNIT

摘要

PROBLEM TO BE SOLVED: To provide a cooling structure practically cooling one body head assembly of a reactor pressure vessel containing a sealed head and a control rod drive mechanism assembly extending upward and reducing refueling time and radiation exposure. SOLUTION: An aseismic support 24 arranged above a sealed head 20 supports the side of a control rod drive mechanism assembly 22. The aseismic support 24 has an air flow hole 84 connecting to the inside of a shroud 32 surrounding the control rod drive mechanism and extending from the sealed head to the aseismic support. The shroud 32 has an air port 96 having relation of direct air connection to the environment. The sealed head 20, shroud 32 and the aseismic support 24 partition air flow path directly connecting to the environment via the air port 96 at low operation power without using wide guide pipe array.