Abstract: A method and an apparatus for measuring the degree of intergranular stress corrosion cracking protection in the area of the core shroud weldments. Electrochemical potential sensors are attached to the shroud wall and the upper core spray line at locations near the actual weld surface of concern to ensure the accuracy of the electrochemical potential measurements. A working electrode doped or coated with noble metal and a reference electrode are implanted into the reactor core shroud. A throughhole is drilled or machined into the shroud wall at an elevation just below the top guide support ring, i.e., near the core shroud weldments. Then a plug containing the working and reference electrodes is inserted into the throughhole.

Abstract: A vacuum system for cleaning the base of a control blade guide tube comprises a vacuum source and a novel vacuum head. The vacuum source includes a conventional vacuum pump and filter, for trapping matter entrained in water driven by the pump. The vacuum head is disk-shaped and has an off-axis vacuum port which can scan the guide tube base when the disk is rotated 360.degree.. Elongated slots in the disk admit water down through the disk. Guide fins separate the slots from the vacuum port. The guide fins are shaped to provide a clearance over the guide tube base, effecting a highventuri action which helps sweep up debris on the guide tube base. An annular ridge on the disk surrounds a similar annular ridge on the base, isolating a control rod drive tube housing below the base from the vacuum. This prevents control rod drive components from being disturbed by the vacuum.

Abstract: An apparatus and process for the remote inspection for stress corrosion cracking of welded shut boiling water reactor shroud access cover plates is disclosed. The apparatus consists of a streamline housing having a top side with lugs for the attachment of lowering lines on either end of the housing. Medially of the streamline housing and projecting downwardly from the bottom of the streamline housing, there is provided a central rotating pedestal with a rubber base. The rotating pedestal and rubber base enable the entire housing to rest on and rotate relative to the pedestal and rubber base. A first motor interior of the housing rotates the housing at a bevel gear rigidly mounted to the central pedestal. A second motor rotates a threaded shaft driving a ball screw with an attached mount for an ultrasound transducer. The mount and transducer responsive to rotation of the ball screw traverse along the elongate dimension of the housing over an opening through the bottom of the housing.

Abstract: In operation, the device is lowered with paired lines attached to both housing lugs but suspended under tension only from one line to one lug so that the streamline housing is vertically disposed. With the housing vertically disposed during lowering, obstacles can be avoided such as the guide rod for the steam separator and dryer as well as the feedwater and core spray spargers. When lowered to the vicinity of the ledge and cover plate to be inspected, the slack line is fished around any obstacle and thereafter placed under tension. The streamline housing is then lowered using both lines in a horizontal position so as to expose downwardly the pedestal and rubber foot. Lowering is completed with remote camera assistance. Sample sweeps with the ultrasound transducer of spaced apart sections of the cover plate weld are used for precise centering of the pedestal and rubber base with respect to the center of the cover plate.

Abstract: In a boiling water reactor, an apparatus and process for ultrasound inspection of the top guide is disclosed. The top guide constitutes a lattice of stainless steel bars overlying the core plate and being assembled at confronting grooves with the lattice mounted at the side edges to the reactor pressure vessel. This lattice braces the upper ends of the vertically supported fuel assemblies in their requisite orientation and spaced apart relation to enable among other things the required spatial interval to be maintained for control rod moderation of the reaction. Because of the proximity of the top guide to the fuel assemblies, the individual bars making up the lattice need to be checked for cracking, especially that cracking produced by irradiation assisted stress crack corrosion. With a defined cell in the lattice emptied of its contained and adjoining fuel assemblies, there is disclosed an ultrasound test for cracking.

Abstract: An apparatus for the remote examination of peripheral shroud hold down bolts on steam separators used in boiling water reactors is disclosed. The testing apparatus is used while the steam separator is in a holding pool. The testing apparatus includes a depending pole having attached at the bottom thereof an aluminum shoe. The shoe has a flat, upwardly exposed bottom and opens to one side at gathering surfaces to receive the lower ends of the shroud bolts. The upwardly exposed bottom of the shoe defines an aperture through which an upwardly exposed piezoelectric device is exposed for direct contact with the bottom of the bolt. An overlying clamp member is provided to clamp the lug onto the bottom of the shoe for testing. The clamp member defines a receiving slot to receive the shaft of the bolt immediately overlying the rectangular lug. The clamp member slides over the shaft at the slot into contact with the top of the lug.

Abstract: Repair apparatus and a method of repair utilized for securing pressure sensing lines to jet pump diffusers in boiling water nuclear reactors is disclosed. Conventional access is made to the reactor with removal of the jet pump inlet mixer to expose the upwardly disposed frustum-shaped diffuser. The diffuser includes a pressure sensing line mounted by a stand off block. It has been found that this pressure sensing line becomes separated from the diffuser due to vibration and accompanying metal fatigue. A repair is effected by introduction of an arcuate beam configured for live support at each end. This pressure sensing line and stand off block is bracketed by the upper end of a beam to register the line to the stand off block. The lower end of the beam brackets the line and stands off from the diffuser at a second introduced stand off block. The line is provided with two points of support to prevent further dislodging vibration.

Abstract: Apparatus for remotely controlled examination of the control rod drive penetration stub tubes in the wall of a nuclear reactor pressure vessel including a rotatable carriage on which is mounted a reciprocable shaft to which is attached an inspection instrument for scanning the stub tubes.

Abstract: A method is disclosed for the compaction of control rod blades and fuel channels of a boiling water reactor. Upper and lower portions of a control rod blade are removed from a cruciform shaped main blade structure. Each elongate tubular fuel channel of substantially square cross section is sectioned into four substantially congruent panels. A plurality of panels are stacked into each quadrant of the main blade structure substantially parallel to the long axis thereof.