Initial-spectrum-independent method for determining neutron energy spectrum in reactor steady-state neutron field

The invention provides an initial-spectrum-independent method for determining neutron energy spectrum in a reactor steady-state neutron field, and discloses a global optimization method for determining neutron energy spectrum by proposing an entropy function for representing neutron energy spectrum distribution and applying a corresponding maximal entropy principle. The initial-spectrum-independent method comprises the following steps of determining a neutron group structure, measuring and recording mononuclear activity of each nuclide, calculating and recording a microscopic cross section of each group of each nuclide, establishing a discrete activation equation set, establishing a probability distributing table of the neutron energy spectrum, and the like. According to the initial-spectrum-independent method disclosed by the invention, the problem that an existing method is dependent on initial spectrum and low in calculating efficiency is solved.