Patent Number: 048428060
Section: claims

1. In a boiling water nuclear reactor having a reactor pressure vessel with a bottom, an internal recirculation pump mounted in said bottom of said vessel, said vessel being at least partially filled with a primary coolant, a reactor core disposed diagonally above said internal recirculation pump, and means for measuring the recirculation flow rate of said coolant, comprising: a flow passage resisting means disposed in a recirculating flow passage of the primary coolant in the reactor pressure vessel and adapted to cause, between an upstream side and a downstream side thereof, a pressure difference in the primary coolant while the flow of the primary coolant is maintained constant;  means disposed at an upstream position and a downstream position relative to said flow passage resisting means for providing a first detecting means for detecting a value of said pressure difference;  means operatively connected to said first detecting means for converting the detected pressure difference value into an electrical signal representing the pressure difference and transmitting the electrical signal; and  means operatively connected to said transmitting means for computing the recirculating flow rate of the primary coolant in response to the electrical signal from said transmitting means;  wherein said flow passage resisting means comprises a plurality of support legs which extend between the bottom of the reactor pressure vessel and a lower end part of a cylindrical shroud disposed within the reactor pressure vessel to partition the interior thereof and serving to support said lower end part of said shroud, and said differential pressure detecting means are disposed, respectively, at upstream and downstream sides of said shroud support legs which are interposed therebetween.  an auxiliary measuring means for measuring a core flow rate of the primary coolant, said auxiliary measuring means comprising means located at upstream and downstream sides of a core support plate and adapted to provide a second detecting means to detect the pressure difference of the primary coolant therebetween;  means operatively connected to said second detecting means and adapted to convert said detected pressure difference value into an electrical signal and transmitting the electrical signal; and  means operatively connected to said transmitting means and operating to compute the core flow rate in response to the signal from said transmitting means. 2. The apparatus according to claim 1 further comprising: