Method for the control of a boiling water reactor and a boiling water reactor for performing said method

Claim 1

A boiling water nuclear reactor with self-regulated reactivity and steam production, and comprising: a. a reactor tank; b. a reactor core enclosed in said tank; c. a riser on the top of said core; d. an inner amount of water between the core and the riser on one hand and the tank on the other hand, the surface level of the water being set below the upper edge of the riser; e. an outer amount of water communicating with said inner amount of water; f. a steam chamber provided with a steam outlet and disposed above and in direct contact with the riser and said surface level of the inner amount of water; g. an internally flowing column of water and steam mixture; extending through the core and the riser, the steam content of said column being produced by the core reactivity and supplied to said steam chamber; h. a water circulation comprising said inner amount of water and said flowing column of water and steam mixture, the driving force of said circulation being constituted by the difference of pressures exerted by said inner water amount and said column, respectively, at the level of the bottom of the reactor core, whereby self-regulation is achieved by the following closed chain of cause and effect: Change of steam chamber pressure -> change of inner amount of water -> change of pressure difference at bottom of the core -> change of water circulating flow -> change of the steam content of the column of water and steam mixture -> change of the core reactivity -> change of steam supply to the chamber -> steam chamber pressure change opposing said given change of steam pressure.