Dry Tube Assemblies

GE manufactures Reuter Stokes SRM/IRM, WRNM, LPRM and universal dry tubes for the boiling water reactor fleet. The dry tube assemblies provide a housing for the sensors and position the sensors in the core region of the reactor.

All of our dry tube assemblies form part of the pressure boundary of the reactor pressure vessel; therefore, their design manufacture and factory testing conforms to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Nuclear Power Plant Components.

The Reuter Stokes SRM/IRM dry tube assembly provides a housing that protects the installed neutron monitoring system sensor from contact with reactor operating pressure, water and steam. The dry tube assembly positions the SRM/IRM sensors in the core region of the reactor and retracts them to a location below the reactor core while the reactor is operating in the power range.

This Reuter Stokes dry tube assembly is a cylindrical tube that serves as a housing for the WRNM sensor. The tube extends from the bottom of the in-core housing, through the in-core guide tube, through the reactor core region and terminates at an anchor point on the top guide. In the core region, the dry tube is located in the open space formed at the intersection of four adjacent fuel channels. The WRNM sensor is inserted into the dry tube from below the reactor pressure vessel and remains in place for the life of the sensor.

The Reuter Stokes LPRM dry tube assembly is a vertically-installed cylindrical tube assembly that serves as a housing for the NA-250 calibration tube and sensor tubes containing the individual sensors and calibration tube. The dry tube assembly provides a means of locating and holding LPRM sensors at their appropriate positions within the reactor core. A calibration tube is provided to permit use of the TIP sensor for scanning the reactor core and calibrating the LPRM sensors.

The Reuter Stokes universal dry tube assembly serves as a housing for either a WRNM or SRM/IRM sensor. The universal dry tube is a partially completed dry tube assembly that is manufactured for stock. By adding a few sections and a plunger assembly, the universal dry tube can be completed in a variety of lengths and plunger configurations as required by different order requirements for the various reactors.

• All components are manufactured from type 304, 304L, 316 or 316L stainless steel.
• Components are manufactured from low carbon (0.035 percent maximum) and low cobalt (0.05 percent maximum) materials to improve component-joining methods and reduce activation, resulting in lower disposal costs.
• Welds are designed to reduce residual stress and heat sensitization.
• All welds are crevice-free, which significantly increases the resistance to IGSCC and IASCC and decreases the frequency of in-vessel visual inspections by 50 percent as compared to older creviced dry tubes.