ASTM E944-08
Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, E706 (IIA)

Standard No.

ASTM E944-08

Release Date

2008

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM E944-13

Latest

ASTM E944-19

Scope

Adjustment methods provide a means for combining the results of neutron transport calculations with neutron dosimetry measurements (see Test Method E 1005 and NUREG/CR-5049) in order to obtain optimal estimates for neutron damage exposure parameters with assigned uncertainties. The inclusion of measurements reduces the uncertainties for these parameter values and provides a test for the consistency between measurements and calculations and between different measurements (see 3.3.3). This does not, however, imply that the standards for measurements and calculations of the input data can be lowered; the results of any adjustment procedure can be only as reliable as are the input data.

Input Data and Definitions:

The symbols introduced in this section will be used throughout the guide.

Dosimetry measurements are given as a set of reaction rates (or equivalent) denoted by the following symbols:

These data are, at present, obtained primarily from radiometric dosimeters, but other types of sensors may be included (see 4.1).

The neutron spectrum (see Terminology E 170) at the dosimeter location, fluence or fluence rate Φ(E) as a function of neutron energy E, is obtained by appropriate neutronics calculations (neutron transport using the methods of discrete ordinates or Monte Carlo, see Guide E 482). The results of the calculation are customarily given in the form of k group fluences or fluence rates.

where:
E_j and E_j+1 are the lower and upper bounds for the j-th energy group, respectively.

The reaction cross sections of the dosimetry sensors are obtained from an evaluated cross section file. The cross section for the i-th reaction as a function of energy E will be denoted by the following:

Used in connection with the group fluences, Eq 2, are the calculated group-averaged cross sections σ_ij. These values are defined through the following equation:

Uncertainty information in the form of variances and covariances must be provided for all input data. Appropriate corrections must be made if the uncertainties are due to bias producing effects (for example, effects of photo reactions).

Summary of the Procedures:

An adjustment algorithm modifies the set of input data as defined in 3.2 in the following manner (adjusted quantities are indicated by a tilde, for example, ?/span>_i):

or for group fluence rates

ASTM E944-08 history

• 2019 ASTM E944-19 Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance
• 2013 ASTM E944-13e1 Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance
• 2013 ASTM E944-13 Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, E???706 (IIA)
• 2008 ASTM E944-08 Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, E706 (IIA)
• 2002 ASTM E944-02 Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, E706 (IIA)
• 1996 ASTM E944-96 Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, (IIA)