Patent Number: 059563800
Section: claims

1. A method for determining the neutron flux density of a neutron-emitting source, which comprises: a) forming a wide-range signal W depending uniquely on a neutron flux density from a first measurement signal S.sub.1 and at least one second measurement signal S.sub.2 differing from one another and each dependent on the neutron flux density;  b) selecting the first measurement signal S.sub.1 as a monotonal function of the neutron flux density for values of the neutron flux density less than a first limit flux density;  c) equating the wide-range signal W to the first measurement signal S.sub.1 in accordance with the relationship W=f.sub.1 (S.sub.1)=S.sub.1 for values of the first measurement signal S.sub.1 corresponding to a neutron flux density less than a lower limit value which is less than the first limit flux density and to which a first signal value N.sub.1 of the first measurement signal S.sub.1 is allocated;  d) forming the wide-range signal W as a function f.sub.2 of the measurement signals S.sub.1, S.sub.2 in accordance with the relationship W=f.sub.2 (S.sub.1, S.sub.2) for values of the first measurement signal S.sub.1 corresponding to a neutron flux density greater than the lower limit value;  e) making the wide-range signal W continuous at the lower limit value in accordance with the relationship f.sub.1 (N.sub.1)=f.sub.2 (N.sub.1, S.sub.2); and  f) using the wide-range signal W as a basis for determining the neutron flux density.  a) selecting the second measurement signal S.sub.2 as a monotonal function of the neutron flux density, and selecting a second limit flux density to be less than the first limit flux density for values of the neutron flux density greater than the second limit flux density; and  b) defining an overlapping region with the lower limit value and an upper limit value, the upper limit value greater than the second limit flux density and less than the first limit flux density, and uniquely allocating a second signal value N.sub.2 of the second measurement signal S.sub.2 to the upper limit value.  a measurement device for producing and transmitting a first measurement signal S.sub.1 and a second measurement signal S.sub.2 differing from one another and each dependent on a neutron flux density, the first measurement signal S.sub.1 being a monotonal function of the neutron flux density for values of the neutron flux density less than a first limit flux density; and  an evaluation device to be connected to said measurement device for forming a wide-range signal W depending uniquely on the neutron flux density and used to determine the neutron flux density, wherein: 2. The method according to claim 1, which comprises: 3. The method according to claim 2, which comprises forming the function f.sub.2 as follows: EQU f.sub.2 =.alpha.(S.sub.2)*S.sub.1 +.beta.(S.sub.1)*S.sub.2 4. The method according to claim 2, which comprises forming the function f.sub.2 in the overlapping region as follows: EQU f.sub.2 =(.alpha.*S.sub.1 +.beta.*S.sub.2)/(.alpha.+.beta.) 5. The method according to claim 2, which comprises equating the wide-range signal W to the second measurement signal S.sub.2 for values of the second measurement signal S.sub.2 to which a neutron flux density greater than the upper limit value is allocated. 6. The method according to claim 2, which comprises determining a further overlapping region immediately adjacent the first-mentioned overlapping region in an analogous manner to the formation of the first-mentioned overlapping region, by using the second measurement signal S.sub.2 and a third measurement signal dependent on the neutron flux density and differing from the first measurement signal S.sub.1 and the second measurement signal S.sub.2. 7. The method according to claim 1, which comprises determining the wide-range signal W as a monotonally rising function of the neutron flux density. 8. The method according to claim 1, which comprises using a measurement signal of one of an ionization chamber, a fission chamber, a boron meter, an SPN detector and a counting tube in each case for the measurement signals S.sub.1, S.sub.2. 9. The method according to claim 1, which comprises using a pulsed signal from an ionization chamber as the first measurement signal S.sub.1, and using a direct-current or alternating-current signal from the ionization chamber as the second measurement signal S.sub.2. 10. The method according to claim 1, which comprises determining the neutron flux density in a nuclear power facility having a reactor core with a plurality of fuel assemblies as the neutron-emitting source, and determining the neutron flux density between the fuel assemblies. 11. The method according to claim 1, which comprises determining the neutron flux density in a nuclear power facility having a reactor core with a plurality of fuel assemblies as the neutron-emitting source, and determining the neutron flux density outside the reactor core. 12. The method according to claim 1, which comprises determining the neutron flux density in a nuclear power facility having a reactor core with a plurality of fuel assemblies as the neutron-emitting source, and determining the neutron flux density between the fuel assemblies and outside the reactor core. 13. An apparatus for determining the neutron flux density of a neutron-emitting source, comprising: