General Electric Company

Lealon C Wimpee

John P Sturtz

Yogeshwar Dayal

John P Neissel

Timothy J O'Neil

Edward M Dean Chu

Monty A Ross

Shelton Steinle

In the core of a boiling water nuclear reactor, local power range monitor strings typically including four vertically spaced monitoring sites are modified. Each monitoring site includes a conventional local power range detector in which fissionable material exposed to thermal neutron radiation produces fission fragments, ionizes a gas and produces a current between the anode and cathode. In the improvement herein, each conventional local power range detector is provided with one or two adjacent gamma thermometers; each gamma thermometer including an interior mass to be heated by gamma radiation, a thermocouple for measuring the heated mass and a reference thermocouple connected in series. Both the conventional local power range detector and the gamma thermometer(s) are all geometrically arranged in a string with individual connecting cables leading to external connectors, one for each detector and gamma thermometer. When the sring is inserted into the core and the reactor operated at a steady state, the gamma thermometers can be utilized to calibrate the local power range detectors in conjunction with a convetional reactor heat balance. By the expedient of referencing the gamma flux to the output of the heat balance, calibration of the local power range monitors occurs over their useful in-service life.

Fixed in-core calibration devices for BWR flux monitors

Assuming knowledge of the number and species of gases present within an enclosed environment such as the atmosphere of a containment vessel of a nuclear plant, an apparatus and process for receiving a gas sample from said atmosphere and measuring the percentages of the various known number and species of gases present is disclosed. Assuming N number of gas species present, N-1 discrete chambers are utilized. Each chamber confines the sample gas, includes a discrete permeation cell having an internal volume isolated from the rest of the chamber by a permeable membrane, and has a pressure sensor for measuring the pressure within the permeation cell resulting from gas permeating through the permeable membrane. Each chamber is isothermal and maintained at its own discrete temperature. Sample gas is introduced into each chamber and allowed to come to equilibrium with the temperature of the chamber. When thermal equilibrium is attained, the permeation cell in each chamber is evacuated by a vacuum pump. Thereafter, gas permeation through each membrane occurs for a given and measured period of time. This period of time is chosen so that the pressure buildup resulting from gas permeating into the cell is but a small fraction of the total sample gas pressure in each chamber. Thereafter, the permeation rates for each cell at each cell's temperature together with the total sample gas pressure are solved in a simultaneous equation format to determine the percentage of each of the N gas species present.

Permeation cell gas detector

Disclosed is a neutron detector, provided with a sealed chamber having two spaced apart electrodes, hermetically sealed in the chamber with a seal which is located in an environment of at least two decades less neutron flux than that experienced by the detector. An ionizable gas is placed within the space between the electrodes, and pressurized to a pressure above one atmosphere. A layer of a mixture of an active material and a breeding material are positioned within the chamber, the active material and breeding material being respectively U-235 and U-234, which layer has a thickness of at least 0.2 milligrams per square centimeter.

Fixed incore wide range neutron sensor

Growing community of inventors

San Jose, CA, United States of America

Lealon C Wimpee