Abstract: A seismic exploration method is disclosed for filtering the signals produced by a detector placed at different depths in a well in response to an emission of acoustic waves from a source on the surface: the signals comprising downgoing wave components and upgoing wave components.The filtering consists in sampling from among the N signals to be processed a group of n signals s.sub.l . . . s.sub.n detected at respective levels x.sub.l . . . x.sub.n, in determining the propagation time t.sub.k of the acoustic waves from the level x.sub.l to each level x.sub.k, in advancing the signals s.sub.k by the time t.sub.k in relation to s.sub.l and in adding s.sub.l and the signals s.sub.k thus shifted to obtain a sum z.sub.l, in calculating a sum y.sub.l of s.sub.l and of the signals s.sub.k delayed by the time t.sub.k in relation to s.sub.l, in generating a signal u.sub.l *, defined as an optimum estimation of the upgoing wave component, from the sums y.sub.l and z.sub.

Abstract: The composition of a geological formation traversed by a borehole is investigated by measuring an energy spectrum of the radiation within the borehole. The measured spectrum is thereafter analyzed by comparing it with a composite spectrum, made up of standard spectra of constituents postulated to comprise the formation-borehole system. As a result of such analysis, the proportions of the postulated constituents in the formation are determined. Where the measured spectrum is subject to degradation due to changes in the resolution of the detector, a filtering arrangement effects modification of the standard spectra in a manner which provides for a more accurate determination of the constituents of the borehole-formation system.

Abstract: The composition of an earth formation is investigated by repetitively irradiating the formation with bursts of incident radiation and generating an unknown energy spectrum from radiation resulting from the interaction of the incident radiation with nuclei of the formation. A background energy spectrum is generated from radiation detected during a time interval adjacent to the interval in which the unknown energy spectrum is measured. A percentage of the background spectrum, shifted to have the best energy-versus-channel number match with that of the unknown spectrum, is then subtracted from the unknown spectrum to produce an improved, unknown spectrum substantially free of background contributions from which an improved, compensated, inelastic neutron interaction log may be generated.

Abstract: A method and an apparatus for quantitatively determining the macroscopic thermal neutron absorption cross-section of a geological formation traversed by a borehole is disclosed. The method comprises the steps of irradiating the formation with neutrons from a continuous source in a neutron sonde and detecting through the use of dual epithermal and thermal detectors the resultant flux of both thermal and epithermal neutrons. Representative signals are then combined in a manner which best takes advantage of the physics of the interaction of neutrons with matter to produce a representation of the macroscopic thermal neutron absorption cross-section. Thus, a signal representing the ratio of the counts is derived from each like pair of detectors. The logarithms of the signals are then taken and combined in a linear combination.

Abstract: A method which determines output parameters (such as porosity .phi. or water saturation S.sub.w of formations) from a set of logging measurements taken at each level of a borehole is proposed.Measurement and response equation uncertainties of each logging apparatus are determined at each measurement level. Assumed values of the output parameters are chosen and, applying the response equations, calculated values of the measurements are determined. The calculated values of the measurements and the actual measurements are then compared to determine deviations which are weighted by factors calculated from the previously determined uncertainties. An incoherence function is determined from the weighted deviations and a number of "a-priori" constraints. Minimization of the incoherence function gives the most probable output parameters whose uncertainty is in turn calculated.

Abstract: A method of merging and rewriting information contained in related data records recorded on first and second sections or files of storage media. (Typically, the "sections" may be individual magnetic tapes.) In accordance with the invention there is provided the step of reading the data records recorded on the first section and rewriting the data records in alternating relationship with dummy data records on a third section of storage media. Related data records recorded on the second section and the third section are read and the information contained therein is merged. The merged information is then written onto the dummy data records on the third section of storage media to obtain merged data records therein. The procedure is repeated sequentially for each related pair of data records on the sections of storage media under consideration.

Abstract: Method and apparatus, for use in the detection of inelastic neutron scattering gamma ray spectroscopy, effect data acquisition efficiency enhancement by operating a neutron generator such that a resulting output burst of fast neutrons is maintained for as long as practicably possible until a gamma ray is detected. Upon the detection of a gamma ray the generator burst output is terminated. Pulsing of the generator may be accomplished either by controlling the burst period relative to the burst interval to achieve a constant duty cycle for the operation of the generator or by maintaining the burst period constant and controlling the burst interval such that the resulting mean burst interval corresponds to a burst time interval which reduces contributions to the detected radiation of radiation occasioned by other than the fast neutrons.

Abstract: Techniques for a broad band high frequency acoustic investigation of a subsurface formation around a borehole are described utilizing a range of acoustic frequencies selected to produce detectable acoustic backscatter from grains within the subsurface formation. The acoustic backscatter is detected and a spectrum thereof is produced and averaged over adjacent subsurface formation regions. A subsurface formation parameter such as the frequency dependency of the attenuation of the backscatter is determined from an analysis of the spectrum to provide an indication of the granularity property of the subsurface formation. Use of a broad range of frequencies enables a determination of the subsurface formation parameter over a large range of grain sizes. In another technique the spectrum of the detected backscatter is modified to remove the effect of the frequency response of the system with which the investigation is made.

Abstract: Method and apparatus are disclosed for investigating lateral characteristics of an earth formation penetrated by a borehole. Substantially identical measurement transducers are mounted in a fixed separation, side-by-side relationship on a pad adapted for sidewall application. As a pad traverses the borehole, measurement signals are produced corresponding to the same formation investigation conducted along two side-by-side paths on the borehole wall. The signals are recorded and provide an indication of lateral changes between the side-by-side paths. By comparing the signals with varying depth displacements, the best likeness and corresponding displacement are determined and provided as an indication of lateral inclination of the formation. The best likeness indicates a lateral formation homogeneity characteristic and the displacement the inclination of the lateral characteristic between the side-by-side paths.

Abstract: The composition of an earth formation is investigated by repetitively irradiating the formation with bursts of fast neutrons and generating an inelastic energy spectrum from gamma ray counts detected during first time intervals which are contemporaneous with the bursts. A second energy spectrum is generated from gamma ray counts detected during second time intervals which immediately follow respective first time intervals. Gamma ray counts comprising the second spectrum are thereafter subtracted from the gamma ray counts comprising the inelastic spectrum to provide an inelastic energy spectrum with reduced background.

Abstract: An alignment system is provided for nuclear fuel assemblies in a nuclear core. The core support structure of the nuclear reactor includes upwardly pointing alignment pins arranged in a square grid and engage peripheral depressions formed in the lateral periphery of the lower ends of each of the fuel assemblies of the core. In a preferred embodiment, the depressions are located at the corners of the fuel assemblies so that each depression includes one-quarter of a cylindrical void. Accordingly, each fuel assembly is positioned and aligned by one-quarter of four separate alignment pins which engage the fuel assemblies at their lower exterior corners.

Abstract: A new part length rod is provided which may be used to not only control xenon induced power oscillations but also to contribute to shutdown reactivity when a rapid shutdown of the reactor is required. The part length rod consists of a control rod with three regions. The lower control region is a longer weaker active portion separated from an upper stronger shorter poison section by an intermediate section which is a relative non-absorber of neutrons. The combination of the longer weaker control section with the upper high worth poison section permits the part length rod of this invention to be scrammed into the core. When a reactor shutdown is required but also permits the control rod to be used as a tool to control power distribution in both the axial and radial directions during normal operation.

Abstract: A new part length rod is provided which may be used to not only control xenon induced power oscillations but also to contribute to shutdown reactivity when a rapid shutdown of the reactor is required. The part length rod consists of a control rod with three regions. The lower control region is a longer weaker active portion separated from an upper stronger shorter poison section by an intermediate section which is a relative non-absorber of neutrons. The combination of the longer weaker control section with the upper high worth poison section permits the part length rod of this invention to be scrammed into the core. When a reactor shutdown is required but also permits the control rod to be used as a tool to control power distribution in both the axial and radial directions during normal operation.

Abstract: A vortex gas separator for the separation of a gas mixture into first and second fractions. The operation of the separator depends on the principle that various gases interact with sorbent substances to greater and lesser degrees. The gas to be separated is tangentially injected into a cylindrical container to create a vortex. The sorbent substance is suspended on the interior of the cylindrical container and interacts with the gases, slowing them down to various degrees. Accordingly, the slowest fraction migrates towards the middle and the fastest fraction is displaced to the circumference. Outlets for the slow fraction and the fast fraction are provided respectively at the axis of the container and at the periphery of the container.

Abstract: A system is provided for the relief of excess pressure from the hot leg of a nuclear reactor to the cold leg on the occurrence of a loss of coolant accident. This system includes a conduit connecting the hot leg with the cold leg. The conduit further includes a check valve which is operated on the basis of differential pressure so that during normal operation the valve is closed.

Abstract: A new part length rod is provided which may be used to not only control xenon induced power oscillations but also to contribute to shutdown reactivity when a rapid shutdown of the reactor is required. The part length rod consists of a control rod with three regions. The lower control region is a longer weaker active portion separated from an upper stronger shorter poison section by an intermediate section which is a relative non-absorber of neutrons. The combination of the longer weaker control section with the upper high worth poison section permits the part length rod of this invention to be scrammed into the core, when a reactor shutdown is required but also permits the control rod to be used as a tool to control power distribution in both the axial and radial directions during normal operation.

Abstract: An automatic motion inhibit system for a nuclear power generating system for inhibiting automatic motion of the control elements to reduce reactor power in response to a turbine load reduction. The system generates a final reactor power level setpoint signal which is continuously compared with a reactor power signal. The final reactor power level setpoint is a setpoint within the capacity of the bypass valves to bypass steam which in no event is lower in value than the lower limit of automatic control of the reactor. If the final reactor power level setpoint is greater than the reactor power, an inhibit signal is generated to inhibit automatic control of the reactor.

Abstract: An improved core servicing apparatus for a nuclear reactor having a vessel, a head for the vessel, one or more penetration openings in the head and a core within the vessel of the type having an array of fuel assemblies and including apertures in the array for neutron absorbers. The servicing apparatus includes a support column adapted to be supported by and depend from the head in registry with a penetration opening; a plurality of core servicing elements which may include neutron absorber actuating means and/or instrument packages are supported by the support column; and means are provided for laterally displacing at least some of the servicing elements relative to the support column between a laterally compact and a laterally expanded configuration.In one embodiment, instruments may be located at the lower end of long resilient cables and are longitudinally movable within and beyond guide channels supported by the support column.

Abstract: An apparatus for the safe storage of a plurality of fissionable masses including an array of discrete neutron absorbing shields which utilizes the principle of the neutron trap to reduce the multipication factor of the storage array to a subcritical value when immersed in a neutron moderating medium. Each discrete neutron absorbing shield is designed to perimetrically encircle each of the stored fissionable masses. Each shield is spaced such that the encircled fissionable mass is spaced from the next adjacent neutron absorbing shield by a distance determined by the enrichment of the fissionable masses and attenuation of the moderating medium.