Abstract: Detecting diversion of spent fuel from Pressurized Water Reactors (PWR) by determining possible diversion including the steps of providing a detector cluster containing gamma ray and neutron detectors, inserting the detector cluster containing the gamma ray and neutron detectors into the spent fuel assembly through the guide tube holes in the spent fuel assembly, measuring gamma ray and neutron radiation responses of the gamma ray and neutron detectors in the guide tube holes, processing the gamma ray and neutron radiation responses at the guide tube locations by normalizing them to the maximum value among each set of responses and taking the ratio of the gamma ray and neutron responses at the guide tube locations and normalizing the ratios to the maximum value among them and producing three signatures, gamma, neutron, and gamma-neutron ratio, based on these normalized values, and producing an output that consists of these signatures that can indicate possible diversion of the pins from the spent fuel assembl

Abstract: Detecting diversion of spent fuel from Pressurized Water Reactors (PWR) by determining possible diversion including the steps of providing a detector cluster containing gamma ray and neutron detectors, inserting the detector cluster containing the gamma ray and neutron detectors into the spent fuel assembly through the guide tube holes in the spent fuel assembly, measuring gamma ray and neutron radiation responses of the gamma ray and neutron detectors in the guide tube holes, processing the gamma ray and neutron radiation responses at the guide tube locations by normalizing them to the maximum value among each set of responses and taking the ratio of the gamma ray and neutron responses at the guide tube locations and normalizing the ratios to the maximum value among them and producing three signatures, gamma, neutron, and gamma-neutron ratio, based on these normalized values, and producing an output that consists of these signatures that can indicate possible diversion of the pins from the spent fuel assembl

Abstract: A method for simulating three-dimensional spatial distribution of neutron and gamma fluences in a nuclear reactor includes, in an exemplary embodiment, generating a detailed geometric configuration of a nuclear reactor core and surrounding components, generating detailed fuel composition and concentration distribution, and calculating three-dimensional nuclide concentrations for the fuel rods and the water surrounding the fuel rods using the generated geometric configuration and generation fuel composition and concentration distributions. The method also includes calculating neutron and gamma fluxes using a Monte Carlo radiation transport criticality mode methodology, and generating a neutron and gamma fluence map for predetermined areas of the reactor.

Abstract: A method for estimating a helium content of the stainless steel core shroud in a boiling water nuclear reactor includes, in an exemplary embodiment, determining a neutron fluence for predetermined areas of the reactor, and estimating a helium content of the stainless steel shroud at predetermined areas of the reactor using the following equation: CHe=1031*(1?e?bj*?j), where CHe is the helium concentration as atomic parts per billion of helium in the stainless steel shroud per weight parts per million of boron in the stainless steel shroud, bj is a value between about 2.50 e?21 and about 5.00 e?21, ?j is fluence expressed as neutrons per square centimeter, and subscript j denotes thermal fluence or fast fluence.

Abstract: A method for simulating three-dimensional spatial distribution of neutron and gamma fluences in a nuclear reactor includes, in an exemplary embodiment, generating a detailed geometric configuration of a nuclear reactor core and surrounding components, generating detailed fuel composition and concentration distribution, and calculating three-dimensional nuclide concentrations for the fuel rods and the water surrounding the fuel rods using the generated geometric configuration and generation fuel composition and concentration distributions. The method also includes calculating neutron and gamma fluxes using a Monte Carlo radiation transport criticality mode methodology, and generating a neutron and gamma fluence map for predetermined areas of the reactor.

Abstract: A borehole logging method for determining the porosity of a formation surrounding the borehole, comprising the steps of: irradiating the formation surrounding the borehole from a location within the borehole with a burst of neutrons, detecting at a near detector indications of the concentration of thermal neutrons following the burst of neutrons and generating near count rate signals as a function of time in response thereto, detecting at a far detector indications of the concentration of thermal neutrons following the burst of neutrons and generating far count rate signals as a function of time in response thereto, fitting a count rate model to the near count rate signals to determine a near impulse formation count rate amplitude, fitting a count rate model to said far count rate signals to determine a far impulse formation count rate amplitude, determining the ratio of the near and far count rate signals as a characteristic proportional to the porosity of the formation.