Two new ANS standards issued

August 27, 2026, 9:34AMANS News

Two new American Nuclear Society standards recently received approval from the American National Standards Institute (ANSI). The new standard ANSI/ANS-56.2-2026, Containment Isolation Provisions for Fluid Systems After a LOCA, is a revision of historic ANS-56.2-1984 (W1999). ANS-GS-30.1-2026, Integrating Risk and Performance Objectives into Standards for New Reactor Designs, is a new guidance standard.

Both standards are available for purchase in the ANS Online Store.

ANSI/ANS-56.2-2026: Containment Isolation Provisions for Fluid Systems After a LOCA specifies minimum design, actuation, testing, and maintenance requirements for the containment isolation of fluid systems that penetrate the primary containment of light water reactors and include piping systems (including instrumentation and control) for all fluids entering or leaving the containment. This standard presents requirements and conditions that are needed for the isolation of the containment and covers requirements for isolation barriers, their actuation, their operators, and connecting piping between isolation barriers.

This standard does not cover penetration assemblies, protection systems, power supplies, electrical systems, and equipment qualification. It does not consider any isolation requirements that may exist for controlled leakage areas either enclosing the primary containment or contiguous to the primary containment, nor does it address containment isolation requirements for events other than loss-of-coolant accidents (LOCAs).

ANS-GS-30.1-2026: The guidance standard Integrating Risk and Performance Objectives into Standards for New Reactor Designs is technology-neutral and applicable to new reactor designs, including modular reactors using light water nuclear technologies and advanced reactors using non–light water nuclear technologies as the basis for their respective designs. Its application to existing reactors is beyond the scope of this standard.

ANS-GS-30.1-2026 specifies objectives for augmenting deterministic nuclear safety design practices using risk-informed, performance-based (RIPB) methods. The application of RIPB methods to high-level safety criteria selection, nuclear safety functions and margin, licensing-basis-event selection, equipment classification, and defense-in-depth adequacy is described to ensure RIPB augmentation of nuclear safety design practices is consistently applied for all new reactor technologies. The information in this guidance standard also can be applied beyond reactor safety into the areas of project risk and reliable and economical plant operation.


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