ISO 18075:2018
(Main)Steady-state neutronics methods for power-reactor analysis
Steady-state neutronics methods for power-reactor analysis
ISO 18075:2018 provides guidance for performing and validating the sequence of steady-state calculations leading to prediction, in all types of operating UO2-fuel commercial nuclear reactors, of: - reaction-rate spatial distributions; - reactivity; - change of nuclide compositions with time. ISO 18075:2018 provides: a) guidance for the selection of computational methods; b) criteria for verification and validation of calculation methods used by reactor core analysts; c) criteria for evaluation of accuracy and range of applicability of data and methods; d) requirements for documentation of the preceding.
Méthodes stationnaires en neutronique pour l'analyse des réacteurs de puissance
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 18075
First edition
2018-03
Steady-state neutronics methods for
power-reactor analysis
Méthodes stationnaires en neutronique pour l'analyse des réacteurs
de puissance
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Terms . 1
3.2 Abbreviations . 4
4 Relation to other standards . 4
5 Methods of calculation . 5
5.1 General . 5
5.2 Conditions to be considered . 5
5.3 Fine-group cross-sections . 6
5.3.1 Basic data . 6
5.3.2 Preparation of fine-group cross-sections . 6
5.3.3 System dependent spectrum calculations . 6
5.3.4 Weighting function . 6
5.4 Preparation of broad-group libraries . 6
5.4.1 General. 6
5.4.2 Choice of cell and supercell . 7
5.4.3 Cell environment. 7
5.4.4 Calculation model . 7
5.5 Collapse to few-groups . 8
5.6 Calculation of reactivity, reaction rate, and neutron flux distributions . 8
5.6.1 Models . 8
5.6.2 Uncertainties and assumptions . 9
5.7 Calculation of reaction rates in reactor components . 9
5.8 Depletion calculations .10
5.9 Common practices .11
5.9.1 Pressurized water reactor (PWR) core physics method .11
5.9.2 Boiling water reactor (BWR) core physics methods .12
5.9.3 Liquid metal reactor (LMR) core physics methods .13
5.9.4 Heavy water reactor HWR core physics methods .15
5.9.5 High temperature gas cooled reactor (HTGR) core physics methods .17
6 Verification and validation of the calculation system .18
6.1 Overview .18
6.2 Verification .18
6.2.1 General.18
6.2.2 Unit testing .18
6.2.3 Integral testing.19
6.3 Validation .19
6.3.1 Unit testing .19
6.3.2 Integral testing.20
6.4 Biases and uncertainties .21
7 Documentation .21
8 Summary of requirements .22
Bibliography .23
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear Energy, Nuclear Technologies,
and Radiological Protection, Subcommittee SC 6, Reactor Technology. This document is based on a
standard developed by the American Nuclear Society (ANS) of which the current version is ANSI/ANS-
[2]
19.3-2011 (R2017) .
iv © ISO 2018 – All rights reserved
Introduction
The design and operation of nuclear reactors require knowledge of the conditions under which a reactor
will be critical, as well as the degree of subcriticality or supercriticality when these conditions change.
In addition, knowledge is required of the spatial distribution of neutron reaction rates in reactor
components as a prerequisite, for example, for inferring proper power and temperature distributions
to ensure the satisfaction of thermal-limit and safety-limit requirements. Both reaction-rate spatial
distributions and reactivity can be and have been measured by suitable experimental techniques, either
in mock-ups or in the operating reactors themselves. These quantities can also be calculated by various
techniques. Available reactor experimental data have been used to validate the steady-state neutronic
calculations within reasonable margins. As more accurate nuclear cross-sections become available and
more refined calculation methods are developed, the reliability of the results of the steady-state power
reactors will be considerably enhanced.
INTERNATIONAL STANDARD ISO 18075:2018(E)
Steady-state neutronics methods for power-reactor
analysis
1 Scope
This document provides guidance for performing and validating the sequence of steady-state
calculations leading to prediction, in all types of operating UO -fuel commercial nuclear reactors, of:
— reaction-rate spatial distributions;
— reactivity;
— change of nuclide compositions with time.
The document provides:
a) guidance for the selection of computational methods;
b) criteria for verification and validation of calculation methods used by reactor core analysts;
c) criteria for evaluation of accuracy and range of applicability of data and methods;
d) requirements for documentation of the preceding.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 Terms
3.1.1
application-dependent multigroup
discrete energy-group structure that is intermediate between the application-independent multigroup
structure and a few-group structure
Note 1 to entry: The application-dependent multigroup structure can be such that the group constants are
dependent on reactor composition through an estimated neutron energy spectrum. An application dependent
Multigroup data set is one type of averaged data set.
3.1.2
application-independent multigroup
discrete energy-group structure that is sufficiently detailed that the group constants may be considered
as being independent of reactor c
...
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