Void effect

The formation of steam or the ingress of gas bubbles in the moderatorMaterial used to "decelerate" fast neutrons to low energies,... and/or the coolantAny substance used to remove the heat in a nuclear reactor. ... influence the criticalityThe condition of a nuclear reactor where a reaction initiate... of the reactorSystem used to initiate, maintain and control a fission chai.... The void effect can be decisively influenced by the design of the reactorSystem used to initiate, maintain and control a fission chai... corePart of the nuclear reactor where the fission chain reaction.... Since e.g. in the case of a thermal reactorSystem used to initiate, maintain and control a fission chai... there is an optimum ratio of moderatorMaterial used to "decelerate" fast neutrons to low energies,... to fuelSee 'nuclear fuel'. volume, there is a void effect with positive coefficient in an excessively moderated reactorSystem used to initiate, maintain and control a fission chai.... An increase in the steam bubble portion increases the neutronUncharged elementary particle with a mass of 1.67492716 ·10... multiplication factorRatio of neutron number in a neutron generation to the neutr... and thus the reactorSystem used to initiate, maintain and control a fission chai... power. In a reactorSystem used to initiate, maintain and control a fission chai... undermoderated due to the corePart of the nuclear reactor where the fission chain reaction... design the conditions are the other way around; here the increase of the steam bubble portion reduces the neutronUncharged elementary particle with a mass of 1.67492716 ·10... multiplication factorRatio of neutron number in a neutron generation to the neutr... and thus the reactorSystem used to initiate, maintain and control a fission chai... power. Therefore, an inherently safeA technical system is called inherently safe if it functions... reactorSystem used to initiate, maintain and control a fission chai... regarding steam bubbles and gas ingress must always be slightly undermoderated; it has a negative void coefficient. See ‘steam bubble coefficient’.