91 results about "Nucleon" patented technology

The invention provides an inertia and magnetic field integration measuring method based on an SERF (spin-exchange-relaxation-free) atomic spin effect. The inertia and magnetic field integration measuring method based on the SERF atomic spin effect comprises the following steps: firstly establishing an overall model for the inertia and magnetic field integration measurement; secondly, manufacturing a measurement sensing unit, and carrying out high-frequency alternating current non-magnetic electric heating; starting a driving laser (z-axis) for carrying out optical pumping on the sensing unit; and emitting a detection laser (x-axis) in a direction vertical to the z-axis; thirdly, carrying out driving magnetic compensation through a three-dimensional magnetic compensation coil so as to counteract a magnetic field of the outside world; fourthly, carrying out azimuth alignment on a main magnetic field and the driving laser and hyperpolarization nucleon self-spin so as to realize the nuclear spin-electron spin strong coupling; fifthly, extracting the information of the atomic spin precession movement in the detection laser by adopting a closed-loop faraday modulation detection method, and obtaining inertia angular speed information; and finally, obtaining the current value of a compensation signal of the magnetic field, and calculating to obtain the information of the current magnetic field. The inertia and magnetic field integration measuring method based on the SERF atomic spin effect has the characteristics of high measurement accuracy and strong autonomy.

The invention discloses a three-axis integrated SERF (Spin-Exchange-Relaxation-Free) atomic spin gyroscope, comprising an alkali metal air chamber, a no-magneto-electricity heating system, a magneticshielding system, a magnetic compensation system, a pumping system and a detection system. The alkali metal air chamber is the sensitive core of a gyroscope, the no-magneto-electricity heating systemcan increase the atom density, the magnetic shielding system can provide an exceedingly low-intensity magnetic field environment, the magnetic compensation system accurately compensate residual field,the pumping system realizes the spin polarization of electrons in the outer layer of the alkali metal and the spin hyperpolarization of inert gas nucleons, and the detection system is used for detecting a rotating signal. According to the invention, by placing two alkali metal air chambers in a same magnetic shielding cylinder, and providing mated pumping and detection systems, three-axis rotarymeasurement can be realized by using one gyroscope, and thus being favorable for improving the precision of the gyroscope, reducing the volume of a navigation system, and widening the application scope of the SERF atomic spin gyroscope.

Ions, particularly molecular ions with multiple dopant nucleons per ion, are produced by charge exchange. An ion source contains a minimum of two regions separated by a physical barrier and utilizes charge exchange to enhance production of a desired ion species. The essential elements are a plasma chamber for production of ions of a first species, a physical separator, and a charge transfer chamber where ions of the first species from the plasma chamber undergo charge exchange or transfer with the reactant atom or molecules to produce ions of a second species. Molecular ions may be produced which are useful for ion implantation.

The invention relates to a method for preparing nano calcium carbonate, belonging to freezing carbonizing, which indicates the processing of digestion, carbonizing, moisture abstraction and drying of the quicklime. The carbonizing procedure includes first carbonizing, the maturing of reaction commingle glue and second carbonizing, and during the optimized preparing procedure, the processing of activating, detracting and surface cladding activating also can be added. As the invention employs two stage carbonizing process, the lime cream can get thoroughly reaction in the carbonizing column, the gas and liquor can contact well, good number of crystal nucleon can be generated well, the particle diameter of the nano calcium carbonate particle is controllable at the range of 20-80nm, and the product quality is stabilizing. The carbonizing time is considerably curtailed, the productivity effect is improved, and this present method needs low productive investment as third of other methods and 80% cost of other methods.

A magnetic resonance position and orientation marking system includes fiducial assembly ( 30 ) with at least three fiducial markers ( 31, 32, 33 ) each coupled with at least one magnetic resonance receive coil ( 70, 74, 80, 84 ). At least one of the fiducial markers has at least one of: (i) marker nuclei selectively excitable over <1>H fat and water resonance, 5 and (ii) a plurality of magnetic resonance receive coils ( 70, 84 ) coupled therewith. At least two magnetic resonance receive channels ( 40, 42 ) receive magnetic resonance signals from the at least three fiducial markers ( 31, 32, 33 ) responsive to excitation of magnetic resonance in said at least three fiducial markers by a magnetic resonance imaging scanner ( 10 ).

A calculation method for fast reactor neutron transportation burn-up coupling analysis comprises the steps of 1, dividing a radial structure of a reactor core into a triangular grid, establishing a triangular prism grid, dividing burn-up regions with axial segmentation of a subassembly as a unit, dividing internal cycle of a reactor into a plurality of burn-up steps, and executing the following steps for each burn-up step; 2, calculating a small group of macroscopic cross-sections of each burn-up region, and carrying out neutron transportation calculation by use of a neutron transportation calculation method based on the triangular prism grid; 3, calculating a burn-up matrix of each burn-up region at the beginning of the burn-up step, and solving a burn-up equation by use of a Chebyshev rational approximation method; 4, carrying out neutron transportation calculation on the reactor core according to a nucleon density vector of each burn-up region at the end of the burn-up step; 5, averaging the burn-up matrixes at the beginning and at the end of the burn-up step to obtain an average burn-up matrix of each burn-up region, and carrying out burn-up calculation on each bur-up region again from the beginning of the burn-up step; and 6, repeating steps 4 and 5 until the nucleon density vectors of each burn-up region at the end of the burn-up step which are obtained through two adjacent calculations are converged.

A detection system, comprises - a particle source (500) for generating a pulsed flux of energetic particles and for directing said flux (140) towards an item (600) to be analyzed, said particles being intended to react with nuclei of material(s) in said item, - a detection unit (400) comprising at least two detector assemblies responsive to particles and / or electromagnetic radiation in respective energy ranges coming from said item and impinging thereon in response to said flux of energetic particles and capable of delivering corresponding time signals, and - a data processing unit (800) connected to the outputs of said detectors, capable of generating a signature from said signals following the application of said pulsed flux to said item, including time-related signal features, and for comparing said signature with stored reference signatures. The present invention also provides a corresponding dection method. Application in particular to airport luggage security clearance, landmine detection, etc.

Nuclear gauges and method of configuration and methods of calibrations of the nuclear gauges are provided. The nuclear gauges are used in measuring the density and / or moisture of construction-related materials. The nuclear gauge can include a gauge housing having a vertical cavity therethrough and at least one radiation detector located within the housing. The nuclear gauge can include a vertically moveable source rod and a radiation source operatively positioned within a distal end of the source rod.

The present invention discloses a method for obtaining sensitivity coefficients of an effective multiplication factor to a section under different burnups. The method comprises: 1, performing forward burnup calculation: first, using a subgroup method to calculate an effective self-shielding section of each nuclide, second, using a modular characteristic line method to solve a neutron angle flux density and a neutron conjugate angle flux density, and third, using a chebyshev rational approximation method to calculate a nuclear density of each nuclide; 2, performing conjugate burnup calculation: first, using the chebyshev rational approximation method to calculate an initial conjugate nuclear density of each nuclide, and then calculating a conjugate power, second, using the modular characteristic line method to calculate a generalized neutron transport angle flux and a generalized conjugate neutron transport angle flux, and third, calculating a conjugate initial nuclear density of each nuclide of a next step; and 3, calculating sensitivity coefficients of the section of each nuclide to an effective multiplication factor under different burnups. The method provided by the present invention solves a defect of the existing method that sensitivity coefficients of an effective multiplication factor to a nuclear section under different burnups cannot be accurately and effectively calculated.

The invention discloses a closed-loop control method for a nuclear-spin self-compensation point of an SERF atomic-spin top. According to the method, an amplitude-frequency characteristic curve and a phase-frequency characteristic which respond to an alternating current magnetic field of a gyroscope are firstly measured, the resonant frequency and the resonant frequency phase position correspondingto an alkali metal electron resonance peak are found out, a longitudinal compensation offset magnetic field is dynamically adjusted in a frequency closed-loop manner or a phase position closed-loop manner, and the alkali metal electron resonance peak is controlled to be unchanged in real time, so that the longitudinal magnetic field sensed by alkali metal electrons is constant, and the closed-loop control of the nuclear-spin self-compensation point is realized. According to the method, the influence caused by the fluctuation of a longitudinal environmental magnetic field and an inert gas nucleon longitudinal magnetic field to the alkali metal electrons can be reduced, signal fluctuation and coupling errors during the measurement of double-shaft angular rate of the SERF atomic-spin top arerestrained, and the linearity degrees of precision and calibration factors of the gyroscope are increased.

The present invention relates to a set of multi-doped cerium-activated scintillation materials of the solid solutions on the basis of the rare earth silicate, comprising lutetium and having compositions represented by the chemical formulas: (Lu2-w-x+2yAwCexSi1-y)1-zMezJjOq and (Lu2-w-x-2yAwCexSi1+y)1-zMezJjOq. The invention is useful for detection of elementary particles and nuclei in high-energy physics, nuclear industry; medicine, Positron Emission Tomography (TOF PET and DOI PET scanners) and Single Photon Emission Computed Tomography (SPECT), Positron Emission Tomography with Magnetic Resonance imaging (PET / MR); X-ray computer fluorography; non-destructive testing of solid state structure, including airport security systems, the Gamma-ray systems for the inspection of trucks and cargo containers.

The invention relates to a snow making machine with adjustable quantity of nozzles of a nucleon device. The snow making machine comprises a water distributor (1), an air compressor (2), an outer annular spraying pipe (3), an inner annular spraying pipe (4) and an air-water mixer (5); a high-pressure water inlet pipe (6) is connected on the water distributor (1); the inner annular spraying pipe (4) is communicated with the water distributor (1) through a valve I (7); a water inlet of the air-water mixer (5) is communicated with the water distributor (1), a water air outlet of the air-water mixer (5) is communicated with the outer annular spraying pipe (3), and an air inlet of the air-water mixer (5) is communicated with an air outlet of the air compressor (2) through a valve II (8); and the air outlet of the air compressor (2) is communicated with the water distributor (1) or the high-pressure water inlet pipe (6) through a valve III (9). With the adoption of the snow making machine provided by the invention, the quantity of the nozzles of the nucleon device can be adjusted according to different field air temperatures, water temperatures, water pressures and air humidity, so that the limitation of a utilization field and an equipment condition is smaller.

A nuclear density gauge and test method is provided for measuring density material in a relatively thin zone beneath a surface of the material. The gauge comprises a gauge housing and a substantially planar base on said gauge housing adapted to be positioned on a surface of the material sample. A gamma radiation source having a characteristic primary energy and an activity of no more than 100 microcurie is mounted within the housing and cooperates with the base for emitting gamma radiation through the base and into an underlying material sample. An energy selective gamma radiation detector is mounted within the gauge housing and in laterally spaced apart relation from the gamma radiation source. The gamma radiation detector is operable for quantifying the energy level of the detected gamma radiation. Shielding is provided within the gauge housing between the source and the detector for preventing gamma radiation from passing directly from said source to the detector. An analyzer is connected to the detector for detecting gamma radiation counts in a predetermined energy spectrum having a lower limit of 0.1 MeV or greater and an upper limit which is less than the characteristic primary energy of said source. The density of the sample is calculated based upon the gamma radiation counts obtainedby the analyzer within the predetermined energy spectrum.

The invention relates to a salt-resistant multielement drip irrigation fertilizer, which is prepared from monopotassium phosphate, urea, potassium chloride, sodium selenate, sodium silicate, magnesium sulphate, zinc chloride, ferrous chloride, manganese chloride, boric acid, calcium chloride, composite chelating agent, acidity conditioning agent and ammonium chloride, wherein the crystal nucleon substance is the mixture of ammonium chloride and potassium chloride by the ratio of 2:1.

The invention discloses a high-temperature snow making method utilizing low-temperature gas for forming ice nucleuses. According to the method, a snow making machine forming the ice nucleuses through the low-temperature gas is utilized for snow making under the high-temperature condition, and the low-temperature gas includes N2 low-temperature gas and CO2 low-temperature gas. A head of the snow making machine used in the method comprises multiple nucleon devices and multiple atomizers. Each nucleon device comprises a water inlet pipeline and a gas inlet pipeline, wherein the low-temperature gas enters from the gas inlet pipeline. According to the method, the low-temperature gas enters artificial snow making equipment from the gas inlet pipelines of the nucleon devices, a traditional manner that air of the nature is compressed and enters nucleon devices for snow making is replaced, meanwhile, optimization design is conducted on the nucleon devices and the atomizers, the snow making equipment can achieve the snow making function at the temperature of -2 DEG C, and indoor ski fields of high-temperature areas of Chinese mainland parts become possible.

The invention provides a paste thickener bottom flow circulation homogenizing device belonging to the field of tailing paste treatment and mineral engineering. The device comprises a bottom flow pump, a nucleon concentration meter, a flowmeter, four valves, a homogenizing device body and a bottom flow circulation pipeline, wherein one end of the bottom flow pump is connected with a material collection well under a paste thickener; the other end of the bottom flow pump is connected with the nucleon concentration meter; the nucleon concentration meter is sequentially connected with the flowmeter, the valve I and the homogenizing device body in series; the valve II is positioned between the flowmeter and the valve I; the valve III and the valve IV are connected in parallel. The homogenizing device body comprises a flange, a pipeline and stirring blades. The rotation speed of the bottom flow pump is adjusted by the bottom flow concentration value and bottom flow value which are obtained in real time by adopting the nucleon concentration meter and the flowmeter so as to selectively switch on the valve III or the valve IV. The paste thickener bottom flow circulation homogenizing device provided by the invention is simple in structure and capable of effectively achieving the homogenization and controllable circulation of bottom flow of the paste thickener, so that the occurrence of raking pressing and stopping accidents of the paste thickener is avoided.

A kind 99mTcN nuclear label coordinate compounds. Its general formula is [99mTcN (PNP1) (DTC) ]+ (T),, that 99mTcN stand for technetium nitrogen centre nucleon, PNP1 stand for diphosphineamine compounds, DTC stand for a amino sulfonate compounds,T as for Tween .- 80. The process is making drug box first, further prepares coordinate compounds needed with radiochemical purity greater than 95%. The prepared label coordinate compound by changing DTC coordinate group and adding auxiliary materials has higher cardiac muscle ingests, well retentivity, higher ratio of heart / liver, heart / lung etc. target / none-target. It can be used as developer for cardiac muscle perfusion or tumour in organs or tissues of human and animals.

The invention discloses a method for processing resonance pseudo-nuclide under a resonance interference effect. The method comprises the following steps that: 1: according to the nuclear density of resonance nuclide, manufacturing a resonance section table of the resonance pseudo-nuclide; 2: fitting by a Pade approximation method to obtain the subgroup parameters of the resonance pseudo-nuclide and sub-resonance nuclide; and 3: solving a subgroup stationary source equation to obtain subgroup flux, and utilizing the subgroup flux to merge the subgroup sections of the sub-resonance nuclide to obtain an effective self-shielding section. In the method, the resonance section table of the resonance pseudo-nuclide is manufactured to consider the resonance interference effect, and the method has higher accuracy and numerical stability than a traditional method.

The invention provides a method for preparation of core-shell, vacant shell structure new materials of amorphous nickel phosphor alloy. The method comprises the following steps: producing the said matrials with metal evoked chemical plating technology, using the polyphenylacetylene globule as mold plates, impregnating the polyphenylacetylene globule in the SnCl2 solvent with the concentration between 0.001-0.1, then deacidizing the predecessor materials, such as Pt, Pt, Ag, Au and so on, forming crystal nucleon of the said metal on the surfaces of polyphenylacetylene globule to activate the suface of polyphenylacetylene globule, finanly firm fixing the amorphous metal-metalloid alloys on the polyphenylacetylene globule with the said metal crystal nucleon evoking by chemical plating , and obtaining the core-shell structure, removing inner core and getting amorphous vacant shell structure with the treatment of solvent. With the method, the amorphous nickel phosphor alloy spherical shell structure new material with the thickness between 50-500nm can be made.

The invention relates to a foundation bearing capacity filling packing in-situ detector, belonging to the geotechnical engineering mechanics field. which comprises: a casing, a crossbeam, a load sensor, a transmission shaft, a sounding rod, a sounding head, a data acquisition processor, a control display panel, a communication interface and a power supply box; The invention is characterized in that: the transmission shaft, the sounding rod and the sounding head is connected with the bottom of the load sensor fixed in the inner cavity of the casing; when the sounding head is inserted into soil mass, the load sensor generates a changeable signal, the signal is sampled, amplified, calculated and displayed by the data acquisition processor, and sent to the upper machine through the communication interface for intelligentizing processing. The invention is distinguished from the penetration test apparatus, sand cone method and nucleon density apparatus used in current engineerings, can solves the following problems in existing technologies: 1, in-situ disturbing dehydration caused by drilling soil sampling, 2, radiation pollution of the nucleon density apparatus, 3, the time and labor consumed in digging pit and filling sand, 4, large error in spring force measuring element, 5, visual error in rule read value and impossibility for keeping data.

Disclosed is a calibration method of an excore detector used in core power monitoring of a nuclear power plant, in which a spatial weighting function (SWF), used to theoretically predict a signal of the excore detector is multiplied by a designated calibration factor to reflect characteristics of the excore detector in a calibration process. It is assumed that the SWF is the multiplication of a one-dimensional shape annealing function (SAF) and a two-dimensional SWF, and the SAF is multiplied by the calibration factor. Since the SAF is calculated in a normalized form, the multiplication of the SAF by the calibration factor to reflect characteristics of the excore detector corresponds to new normalization and thus the calibration of the SAF is referred to as renormalization The signal of the excore detector is considerably accurately predicted by multiplying the theoretically calculated SAF by the renormalization factor, and the multiplication is equally applied although the characteristics of the excore detector are highly changed. An increase in the accuracy of the excore detector in the nuclear power plant prevents unnecessary reactor trips and allows a reactor to be operated at a stable power, thus obtaining the safety of a core and raising economical efficiency.

A receiving system ( 11 ) for connection to an antenna arrangement ( 19 ) for detecting response signals from a substance having quadrupolar nuclei excited so as to produce nuclear quadrupole resonance in certain of the quadrupolar nuclei. A method for receiving a response signal via the antennae arrangement ( 19 ) is also described. The receiving system ( 11 ) includes an amplifier ( 17 ) to amplify the received response signal from the antenna arrangement ( 19 ) for subsequent processing, a matching section ( 15 ) to match the amplifier ( 17 ) to the antenna ( 19 ), and an isolating switch ( 13 ) to isolate the antenna from the receiving system ( 11 ). The matching section ( 15 ) noise matches the receiving system ( 11 ) to the antenna ( 19 ) during a receiving period to reduce the Q factor of the antenna without significantly degrading the signal to noise ratio. The isolating switch ( 13 ) isolates the receiving system ( 11 ) from the antenna ( 19 ) during a transmitting period when an excitation signal is transmitted by the antenna ( 19 ) to irradiate the substance. It also electrically connects the receiving system ( 11 ) to the antenna during the receiving period immediately after the transmitting period.

An NQR scanner for detecting the presence of a substance containing quadrupole nuclei within an object. A pulse generating means ( 1 ) generates pulse sequences that are used to irradiate the object in a pulsed magnetic field at a requisite NQR frequency for the substance to be detected. A high power RF transmit amplifier ( 2 ) amplifies the signal to produce sufficient magnetic field strength to irradiate a scan volume within which the object is disposed for detection purposes and cause an NQR transition to a detectable level within the substance if present within the object. A method for detecting the presence of a substance containing quadrupole nuclei within an object is also described.

The invention relates to a nuclear fuel element doped with technetium-99, which is characterized in that fuel pellets are overlapped to be placed into a zirconium quaternary alloy cladding pipe, after being compressed by a compression spring, two end ports of the cladding pipe are sealed and fixed by an end plug, and the nuclear fuel element is characterized in that each fuel pellet is a mixture of tachnetiuim-99 and uranium dioxide, wherein a ratio of the nuclear density of the technetium-99 and the sum of the nuclear density of technetium-99 and uranium-238 in the uranium dioxide is 10 percent to 90 percent. The resonance characteristic of the technetium-99 is utilized, and the technetium-99 is used for partially substituting the uranium-238 in the enriched uranium fuel, so that three purpose for enhancing the Doppler coefficient, reducing minor actinides nuclide so as to really reduce the minor actinides, guaranteeing the prompt negative temperature coefficient and transforming the nuclear waste technetium-99, and the safety of a reactor can be enhanced.

The invention discloses a rapid measurement method of a 129Xe-Rb spin exchange rate, which is applied to a nuclear magnetic resonance gyroscope. The method comprises the following steps: firstly, heating an alkali metal air chamber; applying a direct-current magnetic field to z axis and applying a non-resonance magnetic field to x axis to obtain a proportional coefficient of an output voltage signal of a ZI phase-locking amplifier and the amplitude of the magnetic field of the x axis; then closing the non-resonance magnetic field and applying a resonance magnetic field to the x axis; finishingthe output of the signal through the ZI phase-locking amplifier; finally, calculating the 129Xe-Rb spin exchange rate. According to the method disclosed by the invention, the blank in the prior art that a rapid and effective rapid measurement method of the 129Xe-Rb spin exchange rate is lacked is filled up and guarantees are provided for improving the nucleon polarizability.

The invention belongs to the technical field of nuclear power, and particularly relates to a reconstruction method and device for burn-up characteristics of reactor core lattice cells. The neutron flux of each energy group in each segment divided in the axial direction of the reactor core assembly and the microscopic cross section of each energy group are determined by adopting a neutron diffusionmodel, and microscopic burnup calculation of a lattice cell level fine grid is carried out on the reactor core by adopting a modulation method. And thus, parameters such as the microscopic reaction rate and the important nuclide nucleon density in the lattice cell can be obtained more accurately. Compared with a neutron transport model, the neutron diffusion model is small in calculation amount and high in speed, so that a large number of calculation resources can be saved, efficient calculation can be realized, parameters such as the microcosmic reaction rate and the important nuclide nucleon density in a lattice cell can be obtained more accurately, and the accuracy and efficiency of reactor core burn-up characteristic calculation are greatly improved.

The invention relates to the technical field of passive nucleon material level measurement, in particular to a method referring to determine a switching point of a switch type passive nucleon material level gage. The method comprises the following steps of: installing the switch type passive nucleon material level gage on a selected position; determining that a material level reaches a preset position, and measuring a gamma ray to obtain a counting rate mean value Nh; determining that the material level is lower than the preset position, and measuring the gamma ray to obtain a counting rate mean value Nl; when Nh>Nl and a measured value> / =Nh, sending full material alarm; when the measured value< / =Nl, eliminating the full material alarm; when Nh<Nl and the measured value< / =Nh, sending the full material alarm; and when the measured value> / =Nl, eliminating the full material alarm. The method provided by the invention is suitable for determining the switching point of the switch type passive nucleon material level gage, provides a foundation for accurately sending full and empty material alarm, increases the selection of users according to actual measurement conditions during measurement through three methods, i.e. a direct return difference method, a motion positioning method and a reference positioning method which can be mutually replaced according to the actual measurement conditions, and can also enhance the data reliability as an inspection method.

The invention discloses a calculation method used for searching for a balanced cycle of a fast neutron reactor. The method comprises the steps of 1, representing a fuel management scheme as multiple fuel management paths; 2, making a fuel cycle process equivalent to an approximate balanced cycle; 3, for the approximate balanced cycle, performing neutron transport and burnup coupling calculation of an in-reactor cycle to obtain a transmutation matrix of each stage of each fuel management path; 4, repeating the steps 2 and 3 until a nuclear density vector of each stage of each fuel management path is converged, thereby obtaining an in-reactor cycle mode; 5, performing linear interpolation or extrapolation on cycle length, and performing a search to obtain the in-reactor cycle mode meeting discharge burnup level requirements; 6, calculating spent fuel reprocessing recovery and new fuel reproducing processes, performing burnup calculation of the in-reactor cycle on a nuclear density vector of newly loaded fuel according to the transmutation matrix, and repeating the processes until the nuclear density vector of the newly loaded fuel of each fuel management path is converged; and 7, adjusting the enrichment degree of the newly loaded fuel to realize a target effective multiplication factor of a specified time point.

The invention relates to the technical field of measurement of passive nucleon levels, in particular to a method for improving the signal-to-noise ratio of a passive nucleon level gage. According to the method, a passive nucleon level measuring device and a calculation technology are provided. The method comprises the following steps that: (a) the passive nucleon level measuring device is provided with two gamma ray detectors, one gamma ray detector is used for monitoring the variable quantity of gamma ray radioactive intensity inside a detected container, and the other gamma ray detector is used for monitoring the variable quantity of environmental gamma ray radioactive intensity outside the detected container; and (b) the variable quantity of the environmental gamma ray radioactive intensity is deducted from the variable quantity of the gamma ray radioactive intensity inside the detected container to eliminate influences of environmental gamma rays and improve the signal-to-noise ratio. By the method, the variable quantity of the environmental gamma rays is included in influence factors and is eliminated, so that the measurement accuracy is improved; and three interchangeable methods are provided, so that influences of the environmental gamma rays on the gamma ray detectors for measuring nucleon levels inside the detected container are eliminated, the selectivity is improved, and the reliability of increased data can be inspected.

The invention discloses a method for designing an axial travelling wave reactor starting area. The method comprises the following steps: (a) setting the length of the reactor starting area; (b) axially dividing the reactor starting area; and (c) setting the nuclear density of each axial section of the reactor starting area. According to the reactor starting area designed by the method, after an axial travelling wave reactor stably runs, fuel compositions in each axial section of a main combustion area are quite complicated and comprise fissionable nuclide, fissile nuclide and fission products. Particularly, the fission products affect reactor core reactivity and power distribution greatly due to the difference of kinds and content of the fission products. The four fuels are adopted, so that the combustion condition can be simulated, and the whole power can be regulated by adjusting the content of each composition.