One of the principal distinguishing characteristics of the RBMK-type reactor is that each core fuel assembly is housed in an individual pressure tube. As was noted previously, the RBMK-1500 core contains 1661 fueled channels separated from its nearest neighbors by the walls of the pressure tubes and graphite blocks. Each pressure tube has considerable autonomy. For example, the coolant flow rate to the tube is controlled online by an individual control valve and additional valves make it possible to decouple it from the primary cooling system while the reactor is in operation. This makes it possible to change fuel clusters online and also has a significant impact on the potential consequences of loss-of-coolant accidents.