ISO 21238-2007 PDF

Full title and description

Nuclear energy — Nuclear fuel technology — Scaling factor method to determine the radioactivity of low- and intermediate-level radioactive waste packages generated at nuclear power plants. This International Standard provides guidelines for empirically deriving scaling factors used to estimate activities of difficult-to-measure radionuclides in low- and intermediate-level radioactive waste (LILW) streams produced at nuclear power plants.

Abstract

ISO 21238:2007 defines the common basic methodology for establishing and applying empirical scaling factors (SFs) that relate easily measured "key" nuclides (typically determined by gamma spectrometry) to difficult-to-measure nuclides (often long-lived alpha or beta emitters). The standard covers representative sampling, sample handling, database construction, statistical evaluation of correlations, treatment of outliers, quality control and documentation. It is intended primarily for waste streams from water-cooled reactors but is also applicable to other reactor types; theoretical (non‑empirical) SF derivation methods are outside its scope.

General information

• Status: Published (confirmed in review 2023).
• Publication date: April 2007 (Edition 1, 2007-04).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 27.120.30 — Fissile materials and nuclear fuel technology.
• Edition / version: Edition 1 (2007).
• Number of pages: 23 pages.

Scope

ISO 21238:2007 provides guidelines for the empirical determination and application of scaling factors to evaluate the radioactivity of difficult-to-measure radionuclides in low- and intermediate-level radioactive waste packages generated at nuclear power plants. It describes sampling strategies to build representative radiochemical databases, procedures for calculating SFs from radiochemical and gamma-spectrometric data, statistical methods for evaluating correlations and uncertainty, record keeping and quality assurance. The standard applies mainly to waste streams from water-cooled reactors but is relevant to other reactor types; it does not cover theoretically derived scaling factors that are not based on experimental measurement.

Key topics and requirements

• Definition and purpose of scaling factors for waste characterization.
• Sampling strategies: homogenized sampling and accumulated sampling to ensure representativeness.
• Requirements for radiochemical analysis and gamma spectrometry used to establish key nuclide activities.
• Database construction and the need for a wide activity-range of samples for effective correlations.
• Statistical evaluation methods for deriving SFs, including treatment and rejection of outliers.
• Classification by waste stream, plant history and reactor type when appropriate.
• Documentation, traceability and record requirements (sample ID, plant, reactor type, waste stream, dates, laboratory performing analysis, detection limits, moisture, decay corrections).
• Limitations and applicability: empirical approach only; theoretical derivations excluded.

Typical use and users

Used by nuclear power plant waste characterization teams, radioactive waste management organizations, decommissioning and remediation projects, analytical laboratories, regulatory bodies and consultants. Typical applications include routine characterization of LILW packages for storage, transport and disposal acceptance, establishing plant-specific SF databases, regulatory reporting and safety-case support.

Related standards

Standards and guidance commonly used alongside ISO 21238:2007 include other ISO/TC 85 publications dealing with radiological measurements and waste characterization, national regulatory guides on waste acceptance, and international guidance such as IAEA publications on waste characterization and radiochemical analysis. Complementary standards for environmental and radiological measurement practice (for example standards addressing gamma spectrometry and sampling quality) are often referenced when implementing the SF methodology.

Keywords

scaling factor; scaling factors; low-level radioactive waste; intermediate-level radioactive waste; LILW; waste characterization; nuclear power plant; sampling; radiochemical analysis; gamma spectrometry; difficult-to-measure nuclides; waste package declaration; ISO 21238:2007.

FAQ

Q: What is this standard?

A: ISO 21238:2007 is an International Standard that specifies an empirical scaling factor method to estimate activities of difficult-to-measure radionuclides in low- and intermediate-level radioactive waste packages from nuclear power plants.

Q: What does it cover?

A: It covers representative sampling approaches, analytical data requirements, database construction, statistical methods to derive scaling factors, handling of outliers, quality control and documentation. It applies mainly to water-cooled reactor waste streams and to other reactor types where appropriate; it excludes purely theoretical scaling-factor derivations.

Q: Who typically uses it?

A: Nuclear utility waste characterization groups, waste-management organizations, analytical laboratories, decommissioning teams, regulators and consultants use the standard to establish and apply SFs for routine package characterization, transport and disposal acceptance.

Q: Is it current or superseded?

A: The document was published in April 2007 (Edition 1). It has undergone routine ISO review and was confirmed in the periodic review cycle (confirmed in 2023), so the 2007 edition remains the current edition as of the last ISO confirmation.

Q: Is it part of a series?

A: ISO 21238:2007 is a standalone International Standard within the work of ISO/TC 85 (nuclear energy), specifically prepared by SC 5 (nuclear installations, processes and technologies). It is often used together with other ISO and international guidance documents on radiological measurement and waste management but is not formally a numbered multi‑part series.

Q: What are the key keywords?

A: Key keywords include: scaling factor, waste characterization, difficult-to-measure nuclides, low- and intermediate-level radioactive waste, sampling, radiochemical analysis, gamma spectrometry, nuclear power plant.