ANS standards updates

May 12, 2020, 1:29PMNuclear News

ANS publishes standards that set forth requirements for the design, manufacture, or operation of a piece of equipment. These standards can address computer firmware and software, and can address the necessary physical and functional features of equipment, its safe application, or some combination of these. These standards are applied on a voluntary basis, and when adopted by a state or federal agency, they becomes part of their mandatory codes.

ANS standards are available at the ANS Standards store.

The following standards have been approved, published, or are open for comment.

Standards Approved

The following standards have been approved:

ANSI/ANS-5.4–2011 (R2020), Method for Calculating the Fractional Release of Volatile Fission Products from Oxide Fuel (reaffirmation of ANSI/ANS-5.4–2011).

This standard provides an analytical method for calculating the release of volatile fission products from uranium dioxide fuel pellets during normal reactor operation. When used with nuclide yields, this method will give the release-to-birth ratio, or the so-called gap release, which is the inventory of volatile radioactive fission products that could be available for release from the fuel rod if the cladding were breached.

ANSI/ANS-6.6.1–2015 (R2020), Calculation and Measurement of Direct and Scattered Gamma Radiation from LWR Nuclear Power Plants (reaffirmation of ANSI/ANS-6.6.1–2015).

This standard defines calculational requirements and discusses measurement techniques for estimates of dose rates near light-water reactor nuclear power plants due to direct and scattered gamma-rays from contained sources on-site. On-site locations outside plant buildings and locations in the off-site unrestricted area are considered. All sources that contribute significantly to dose rates are identified, and methods for calculating the source strength of each are discussed. Particular emphasis is placed on nitrogen-16 sources, as they are significant sources of direct and scattered radiation for boiling water reactors. The standard specifically excludes radiation from gaseous and liquid effluents. The standard describes the considerations necessary to compute dose rates, including component self-shielding, shielding afforded by walls and structures, and scattered radiation. The requirements for measurements and data interpretation of measurements are given. The standard includes normal operation and shutdown conditions but does not address accident or normal operational transient conditions. The standard also applies to the gamma dose resulting from dry fuel storage facilities.

ANSI/ANS-58.16–2014 (R2020), Safety Categorization and Design Criteria for Nonreactor Nuclear Facilities (reaffirmation of ANSI/ANS-58.16–2014).

This standard provides guidance and criteria for the safety classification of safety functions and associated hazard controls (such as structures, systems, components [SSC] and administrative controls) associated with nuclear safety in nonreactor nuclear facilities. This standard provides guidance on how to derive safety functions and the design and operational requirements to satisfy these functions. It also associates the safety classification of hazard controls to engineering (e.g., civil/structural, mechanical, electrical) and programmatic (e.g., quality assurance) classification levels. Finally, this standard will define functional and boundary criteria for safety SSCs to include associated SSCs necessary for the operation of a safety SSC when called upon to provide its safety function.

ANS-2.27–2020, Criteria for Investigations of Nuclear Facility Sites for Seismic Hazard Assessments (revision of ANSI/ANS-2.27–2008; R2016).

This standard provides requirements and recommended practices for conducting investigations and acquiring data sets needed to characterize seismic sources for probabilistic seismic hazard analysis of both vibratory ground motion and permanent tectonic surface deformation. The data sets provide information for site response and soil structure interaction effects needed for designing nuclear facilities. The data sets are also used to evaluate other seismically induced ground failure hazards (e.g., liquefaction, ground settlement, slope failure).

ANS-2.29–2020, Probabilistic Seismic Hazard Analysis (revision of ANSI/ANS-2.29–2008; R2016).

This standard provides criteria and guidance for performing a probabilistic seismic hazard analysis that is used in the design and construction of nuclear facilities (i.e, facilities that store, process, test, or fabricate radioactive materials in such form and quantity that a nuclear risk to the workers, to the off-site public, or to the environment may exist). These include, but are not limited to, nuclear fuel manufacturing facilities; nuclear material waste processing, storage, fabrication, and reprocessing facilities; uranium enrichment facilities; tritium production and handling facilities; radioactive materials laboratories; and nuclear reactors.

Standard published

ANSI/ANS-2.8–2019, Probabilistic Evaluation of External Flood Hazards for Nuclear Facilities (new standard).

This standard addresses the necessary external flood conditions, technical parameters, and applicable methodologies required to evaluate/determine external flooding hazards for nuclear facilities.

Comments requested

Comments are requested on the following standard by June 15, 2020:

ANS-58.9–2002 (R202x), Single Failure Criteria for Light Water Reactor Safety-Related Fluid Systems (reaffirmation of ANSI/ANS-58.9–2002; R2015).

This standard provides criteria for the designer that interpret the requirements of Title 10, Code of Federal Regulations, Part 50, Licensing of Production and Utilization Facilities, Appendix A, “General Design Criteria for Nuclear Power Plants,” with respect to design against single failures in safety-related light-water reactor fluid systems. Means of treating both active and passive failures are addressed for safety-related fluid systems following various initiating events. Current acceptable practice is used as a basis for these criteria. Failure criteria for the electric power systems and the protection systems are provided in IEEE Standard 308-1980, Criteria for Class 1E Power Systems for Nuclear Power Generating Stations; IEEE Standard 279-1971, Criteria for Protection Systems for Nuclear Power Generating Stations (ANSI N42.7-1972); IEEE Standard 379-1977, Application of the Single-Failure Criterion to Nuclear Power Generating Station Class IE Systems; and IEEE Standard 603-1980, Safety Systems for Nuclear Power Generating Stations. Failures of structural components, such as braces, supports, or restraints, as well as occurrences involving common-mode failures, are excluded.

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