Method and apparatus for measurement of terminal solid solubility temperature in alloys capable of forming hydrides

Abstract

An apparatus and method for measuring terminal solid solubility in materials capable of forming hydrides, such as reactor pressure tubes. An inspection device is positioned within the reactor pressure tube under test and a pair of annular seals are radially deployed to seal a section of the pressure tube. Any water within the sealed section is displaced through the injection of gas and the heating of the sealed section to dry the tube and the device. A probe assembly on the device is deployed to contact the interior surface of the pressure tube and measure resistivity changes in the pressure tube wall as a function of temperature. The probe assembly includes a thermocouple probe for measuring temperature and transmit and receive coils for inducing eddy currents within the pressure tube wall. The pressure tube is allowed to cool at a predetermined rate, is reheated at a predetermined rate, and is allowed to cool again. Discontinuities within the temperature coefficient of resistivity indicate terminal solid solubility temperatures of precipitation or dissolution, which may be used to determine the hydrogen concentration of the sealed section of reactor pressure tube.

1 . An inspection device for inspecting reactor pressure tubes, comprising: (a) a device body; (b) deployable seals mounted on said device body for sealing a section of the reactor pressure tube; (c) a heater for controlling a temperature change within the reactor pressure tube at a predetermined rate; and (d) a probe assembly for measuring changes in the resistivity of the reactor pressure tube in relation to the temperature change. 
   
   
       2 . The inspection device claimed in  claim 1 , wherein said device body includes a cylindrical pipe. 
   
   
       3 . The inspection device claimed in  claim 1 , wherein said deployable seals include substantially annular seals and inflatable bladders for deploying said annular seals radially to press against an interior surface of the reactor pressure tube. 
   
   
       4 . The inspection device claimed in  claim 1 , further including a gas manifold system and an inert gas supply for deploying said seals. 
   
   
       5 . The inspection device claimed in  claim 1 , wherein said heater includes an induction heater and a resonant capacitor assembly within said body and coupled to said heaters. 
   
   
       6 . The inspection device claimed in  claim 5 , wherein said device body is cylindrical and said induction heaters are disposed circumferentially around said device body. 
   
   
       7 . The inspection device claimed in  claim 1 , wherein said probe assembly includes an eddy current system and a thermocouple probe for measuring resistivity and temperature respectively. 
   
   
       8 . The inspection device claimed in  claim 7  wherein said eddy current system includes a receive coil and a transmit coil. 
   
   
       9 . The inspection device claimed in  claim 8 , wherein said probe assembly further includes a probe body and wherein each of said transmit coil, said receive coil, and said thermocouple probe are embedded in an outer surface of said probe body. 
   
   
       10 . The inspection device claimed in  claim 9 , wherein said probe assembly further includes a deployment mechanism coupled to said probe body for extending said probe body radially to contact an inner surface of the reactor pressure tube with said outer surface of said probe body.