Westinghouse Electric Corporation

Westinghouse Electric Company LLC

David E Boyle

Robert B Salton

James R Chrise

James A Rex

Luciano Veronesi

Robert E Meuschke

Stephen N Tower

Bruce W Bevilacqua

Leonard R Golick

George E Rudd

Leonard J Balog

Howard E Braun

Richard E Schwirian

Ian L Wilson

David H Roarty

Edward J Rusnica

Stephan L Abbott

Albert C Davidson

John C Matarazzo

Theodore A Meyer

William E Klassen

Howard F Fensterer

Moshe A Mahlab

Kimchinh Tran

Robert L Turner

Raman G Patel

An apparatus and method are provided for inverting the lower internal assembly of a nuclear reactor. The apparatus includes a frame which is sized to receive the lower internal assembly. The frame supports the lower internal assembly as it is being inverted. The apparatus also includes a spider assembly which fits within the lower internal assembly and provides support for a baffle assembly located therein. The method includes the steps of removing the lower internal assembly from a reactor vessel and rotating the lower internal assembly prior to performing maintenance.

Lower reactor internals up-ending device

A high strength bolt fastens a baffle plate and a former plate of a pressurized water nuclear reactor pressure vessel together. The bolt has a head portion and an integral locking member extending from the head portion for engaging one of the structural members to lock the bolt with the structural member. The integral locking member portion has a lower yield stress than the yield stress of the shank. A lower yield stress may be obtained by selective annealing. The locking member is less susceptible to stress corrosion cracking in high temperature, high pressure water of commercial nuclear power reactors.

Bolt with integral locking member

A control rod guide tube mounting pin for engaging a hole in an upper core plate of a nuclear reactor pressure vessel has a resilient tubular portion with one or more axial crimps which flex allowing for resiliently fitting into a hole in an upper core plate without needing to enlarge or other machine the existing holes or drilling additional holes. Stainless steel mounting pins may be backfit into existing two pin mounting systems of control rod guide tubes adjacent to the outlet nozzles of the pressure vessels by removing the pins mounting the guide tubes adjacent the outlet nozzles to the upper core support plate; and then replacing the removed pins with stainless steel replacement pins.

Control rod guide tube mounting pin

A new system is provided for control rod guidance support with wear mitigating features in a nuclear reactor pressure vessel. The upper guide tube and the lower guide tube structures house the control rod when it is withdrawn from the fuel core. The upper guide tube has a top enclosure plate with a drive rod opening therethrough sized to provide a predetermined clearance space between the drive rod and the top enclosure plate and to direct coolant flow between the upper and outlet plenums and through the guide tube assembly to allow transmittal of upper plenum bypass cooling flow to the outlet plenum. Structure is provided for restricting coolant flow through the top plate clearance space to reduce control rod wear. A coupler secures the drive and control rods in end-to-end relation within the guide tube assembly. The coupler is located just below the top guide tube enclosure plate with the control rod fully withdrawn. The coolant restricting structure includes a flow restricting sleeve secured to the coupler and extending upwardly over the drive rod through the top guide tube enclosure plate. A flow restrictor is located above and secured to the top guide tube enclosure plate, and it has an upper portion disposed about and spaced from the flow restricting sleeve to provide a flow gap having a flow area substantially equal to the clearance space. The flow restrictor is otherwise structured to provide at least one contraction-expansion loss above the top guide tube plate for guide tube coolant flow through the flow gap.

System providing improved guidance support with restricted coolant flow

A mounting system for removably mounting the lower flange of the control rod guide tube over an opening in the upper core plate of a nuclear reactor is disclosed. The system includes a pair of resilient pin members and a pair of reinforcing pin members. The resilient pin members are mounted in a passage formed through first opposing sides of the guide tube lower flange. They are resiliently receivable in first bores formed on first opposing sides of the upper core plate to permit deflection thereof when the guide tube is subject to normal shear loads. The resilient pin members bear substantially all of the normal shear load to which the guide tube is subjected. The reinforcing pin members are mounted on the second opposing side of the guide tube lower flange. They are receivable in second bores formed on the second opposing sides of the upper core plate with a clearance. The reinforcing pin members bear substantially all of the abnormal shear load that exceeds the normal shear load. The clearance between the reinforcing pin members and the second bores limits the deflection of the resilient pin members. After the resilient pin members deflect the distance limited by the clearance, the reinforcing pin members bear any additional abnormal shear loads and prevent the additional abnormal shear loads from bearing on the resilient pin members.

Four pin mounting system for nuclear reactor control rod guide tubes

A shield panel for use in a nuclear reactor including a reactor vessel susceptible to embrittlement when bombarded with high energy neutrons and a nuclear reactor core mounted within the reactor vessel, the reactor vessel having a longitudinal axis and an inner surface surrounding the longitudinal axis, and the nuclear core emitting high energy neutrons which impinge on the inner surface of the reactor vessel. The shield panel includes a canister which contains a completely enclosed interior space and which is mountable between the inner surface of the reactor vessel and the nuclear core in a region wherein the reactor vessel is susceptible to a higher rate of embrittlement than the remaining portion of the vessel when bombarded with high energy neutrons emitted from the nuclear core, and a substance consisting essentially of a heavy metal and hydrogen filling the interior space of the canister.

Neutron shield panel arrangement for a nuclear reactor pressure vessel

An inservice inspection of a surface area or welds of a nuclear reactor pressure vessel is carried out, without the need to remove the core barrel and lower internals therefrom, by providing access to the annular chamber between the core barrel and the pressure vessel wall through an aperture in the upper flange of the core barrel. An inspection means, such as an ultrasonic testing device is inserted into the annular chamber through the access and positioned proximate the weld to be inspected and inspection of the weld effected by the device.

Method for internal inspection of a pressurized water nuclear reactor

A method and apparatus for extending the life of a core of a water moderated nuclear reactor by spectral shift comprising the displacement of a portion of the moderator in the core by a gas having a low neutron cross-section during the initial stage of the life of the core and displacing the gas and replacing it with moderator during the latter part of the life of the core.

Gas displacement spectral shift reactor and control method

Apparatus is disclosed for introducing a low neutron moderating fluid into the reactor vessel of a spectral shift pressurized water nuclear reactor and for distributing the moderating fluid through the lower core support plate into the fuel assemblies in the core.

Fluid moderator control system reactor internals distribution system

A quick release guide sleeve assembly comprises an outer sleeve, an inner sleeve axially slidably received in the outer sleeve and having first and second axial positions with respect to the outer sleeve; and a locking mechanism movably mounted on the outer sleeve for frictionally engaging wall surfaces defining an opening for receiving the outer sleeve. The locking mechanism has a locking position in which at least part of the locking mechanism projects radially outwardly beyond the external circumferential surface of the outer sleeve. The locking mechanism further has a releasing position in which the locking mechanism is in a radially inwardly withdrawn state relative to the circumferential surface of the outer sleeve. The assembly further includes a camming arrangement carried on the inner sleeve for pressing the locking mechanism into the locking position when the inner sleeve is in the first axial position and for allowing the locking mechanism to assume the releasing position when the inner sleeve is in the second axial position. A spring urges the inner sleeve continuously into the first axial position.

Quick release guide sleeve assembly

A mechanical drive system (10) for moving alternate nuclear reactor fuel rods (14) within the nuclear reactor core (12) and relative to the remaining stationary nuclear reactor fuel rods (16) so as to axially displace the movable fuel rods (14), and enriched and natural uranium fuel zones defined therein, relative to similarly defined enriched and natural uranium fuel zones within the stationary fuel rods (16) in order to optimize utilization of excess or free neutrons produced within the nuclear reactor core within a fuel cycle. The nuclear reactor fuel rods (14, 16) all have a length which is less than that of standard-sized nuclear reactor fuel rods, and therefore, a plenum chamber (20) is able to be defined between an upper core plate (22) and an auxiliary upper core plate (24). A drive plate grid assembly (36, 38) is attached to the movable fuel rods (14), and hydraulic drive mechanisms (46) move the grid assembly (36, 38) and the movable fuel rods (14) so as to axially displace the fuel rods (14) relative to the stationary fuel rods (16) whereby the enriched and natural uranium fuel zones defined within the fuel rods (14, 16) optimally operationally interface throughout the fuel cycle. The movable fuel rods (14) are progressively moved during the fuel cycle such that at the beginning of the fuel cycle, the enriched and natural uranium fuel zones defined between adjacent fuel rods (14, 16) are mis-aligned, while at the end of the fuel cycle, the fuel zones are aligned in horizontal layers.

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Pittsburgh, PA, United States of America

David E Boyle