Abstract: An organic iodine remover is a remover for removing organic iodine and is a substance composed of a cation and an anion, and the cation (for example, a phosphonium cation, an ammonium cation, or a sulfonium cation) has a molecular structure in which an electron donating group (for example, a phosphino group, an amino group, a sulfanyl group, a hydroxy group, or an alkoxy group) is bonded to a phosphorus atom, a nitrogen atom or a sulfur atom. An organic iodine removing apparatus includes: a vessel into which the organic iodine remover for removing the organic iodine is charged; and introduction pipes through which a fluid containing organic iodine is introduced into the organic iodine remover.

Abstract: As an organic iodine remover that removes organic iodine in a containment vessel of a nuclear reactor, an organic agent (for example, an ionic liquid, an interfacial active agent, a quaternary salt, or a phase transfer catalyst) having a function of dissolving and decomposing the organic iodine and retaining iodine is used. The organic iodine remover is a substance composed of a cation and an anion. The organic iodine remover is, in particular, an organic iodine remover in which, in a structure of the cation of the organic agent, carbon or oxygen is bonded to, via a single bond, to a phosphorus element, a sulfur element or a nitrogen element, the number of carbon chains is 2 or more, and an anionic structure is configured with a substance with high nucleophilicity. By using such an organic agent, the organic iodine is removed with an efficiency of 99% or more.

Abstract: An organic iodine trapping apparatus and method efficiently traps organic iodine in a nuclear reactor container vessel. A liquid vessel contains a non-volatile liquid (e.g., ionic liquid or interfacial active agent solution) capable of decomposing organic iodine. An introduction pipe introduces a fluid containing organic iodine in the nuclear reactor container vessel to the non-volatile liquid. The non-volatile liquid is heated by heat in the nuclear reactor container vessel or reaction heat of the fluid in the nuclear reactor container vessel. Then, the trapping apparatus decomposes and traps the organic iodine. The organic iodine trapping method includes heating a non-volatile liquid capable of decomposing organic iodine by heat in the nuclear reactor container vessel or reaction heat of fluid in the nuclear reactor container vessel; making the fluid containing organic iodine pass through the heated non-volatile liquid; and decomposing and trapping the organic iodine in the non-volatile liquid.

Abstract: The invention is directed to a natural circulation reactor having a reactor pressure vessel with a core housed therein, the core being disposed in such a location that a top portion of the core is submerged under coolant even in the event that any pipe connected to the reactor pressure vessel is broken and then a coolant level in the reactor pressure vessel is lowered due to flushing. This permits the reactor core to be submerged under coolant even in the event of breakage of any pipe connected to the reactor pressure vessel, ensuring to eliminate a possibility that the top portion of the reactor core is exposed temporarily during an intermediate period before actuation of an accumulated coolant injection system to start injecting of the coolant into the reactor pressure vessel after the end of flushing.