ISO 19226:2017 原子力エネルギー—原子炉容器と内部の原子あたりの中性子フルエンスと変位（dpa）の決定 | ページ 6

3.1

accuracy of a measured/calculated value

difference between the “real” and the measured/calculated value, typically due to systematic errors in the measurement/calculation procedure

3.2

benchmark experiment

well-defined set of physical experiments with results judged to be sufficiently accurate for use as a calculational reference point

Note 1 to entry: The judgment is made by a group of experts in the subject area.

3.3

best-estimate fluence

most accurate value of the fluence based on all available measurements, calculated results, and adjustments based on bias estimates, least-squares analyses, and engineering judgment

3.4

calculational methodology

mathematical equations, approximations, assumptions, associated parameters, and calculational procedure that yield the calculated results

Note 1 to entry: When more than one step is involved in the calculation, the entire sequence of steps comprises the “calculational methodology.”

3.5

code benchmark

comparison to the results of another code system that has been previously validated against experiment(s)

3.6

continuous-energy cross-section data

cross-section data that are specified in a dense point-wise manner that comprises the energy range

3.7

dosimeter reaction

neutron-induced nuclear reaction with a product nuclide having sufficient activity to be measured and related to the incident neutron fluence

3.8

displacements per atom (dpa)

mean number of times each atom of a solid is displaced from its lattice site during an exposure to displacing radiation, as calculated following standard procedures

3.9

least-squares adjustment procedure

method for combining the results of neutron transport calculations and the results of dosimetry measurements that provides an optimal estimate of the fluence by minimizing, in the least-squares sense, the calculation-to-measurement differences

3.10

multigroup cross-section data

cross-section data that have been determined by averaging the continuous-energy cross-section data over discrete energy intervals using specified weighting functions to preserve reaction rates

3.11

neutron fluence

time-integrated neutron fluence rate (i.e. the time-integrated neutron flux) as expressed in neutrons per square centimeter

3.12

precision of a measured/calculated value

standard deviation (if available from a set of repeated measurements/calculations) of the distribution of the measured or calculated physical value

3.13

reactor internals

reactor structure components that are within the pressure vessel such as the core baffle, core barrel, thermal shield, lower and upper core plates in PWRs and BWRs

3.14

solution variance

measure of the statistical variance of the Monte Carlo transport solution due to a finite number of particle histories

Note 1 to entry: Mathematically, it is the second central moment of the distribution about the mean value, which is used to measure the dispersion of the distribution about the mean.