NP 094-15 PDF

Full title and description

NP 094-15 — "Basic requirements for justification of strength and thermo-mechanical behavior of fuel assemblies and fuel elements in the nuclear core of pressurized water reactors". This federal norm and rule establishes mandatory requirements for demonstrating structural strength, long-term integrity and thermo‑mechanical performance of fuel assemblies and fuel elements for VVER (water‑water energetic) type reactors under normal operation, anticipated operational occurrences and design‑basis accidents.

Abstract

NP 094-15 defines criteria, calculation methods and experimental substantiation needed to justify the mechanical strength and thermo‑mechanical behaviour of fuel assemblies (TВС) and fuel elements used in the reactor core of pressurized water (VVER) reactors. It covers material properties and acceptance criteria, static and dynamic strength, fatigue and creep considerations, stability, brittle fracture resistance, vibrational and dynamic loading, progressive deformation, corrosion‑related strength, and requirements for computational and experimental validation. The document includes appendices with terms, symbols and load combinations.

General information

• Status: Active (in force / действует).
• Publication date: Approved by order (18 January 2016); entry into force 7 May 2016; recorded updates/actualization available (last noted update: 1 January 2021).
• Publisher: Federal Service for Environmental, Technological and Nuclear Supervision (Rostekhnadzor) — issued on the official legal information portal of the Russian Federation.
• ICS / categories: Nuclear engineering / reactor technology (relevant classification: OKС / ICS area for reactor core and fuel technology; bibliographic identifiers in sources include UDC and OKС codes related to reactor technology).
• Edition / version: Designation NP‑094‑15 (issued 2016). Document is referenced with that identifier in official collections and libraries.
• Number of pages: Approximately 40–42 pages (standard published as a concise rule set; many catalog listings note 41 pages).

Scope

The standard applies to justification reports, calculations and experimental substantiation prepared for fuel assemblies and fuel elements of pressurized water reactors (VVER type) at design, construction and operation stages. It covers normal operation, deviations from normal operation and design‑basis accident conditions. The requirements are intended for organizations that prepare strength and performance justifications and for regulatory review by the supervising authority.

Key topics and requirements

• Definitions, abbreviations and fundamental provisions for strength and thermo‑mechanical justification.
• Requirements for physical and mechanical properties of structural materials used in fuel elements and assemblies.
• Criteria for strength and operability of individual fuel rods (elements) and for whole fuel assemblies.
• Safety factors and margins for different failure modes (static strength, brittle fracture, stability, vibration).
• Calculation methods for static, cyclic (fatigue), long‑term (creep and creep‑fatigue interaction) and dynamic loads, including progressive deformation analyses.
• Load combinations, allowable stresses, and special rules for dynamic and vibrational impacts.
• Requirements for experimental programs and validation tests used to substantiate computational models and acceptance criteria.
• Appendices with terms, symbols, stress categories and recommended combinations of loads.

Typical use and users

Primary users are fuel designers and manufacturers, reactor core design engineers, safety analysts, independent technical reviewers, testing laboratories and regulatory authorities responsible for nuclear safety oversight. The document is used during the design and licensing of fuel designs, in periodic safety justification updates and when performing strength and thermo‑mechanical assessments for modifications or lifetime evaluations.

Related standards

NP 094-15 is part of the Russian federal norms and rules series governing nuclear energy use and is referenced alongside other NP documents and national standards on fuel assembly strength and reactor safety. Subsequent and related standards and national GOST/R documents address specialized calculation methods for fuel assembly strength (for example, later national standards on strength calculations for dynamic loads and other aspects of TVS design).

Keywords

fuel assembly, fuel element, TVS, VVER, pressurized water reactor, strength justification, thermo‑mechanical behavior, fatigue, creep, brittle fracture, vibrational strength, dynamic loads, experimental validation, Rostekhnadzor.

FAQ

Q: What is this standard?

A: NP 094-15 is a Russian federal norm and rule that sets out mandatory requirements for demonstrating the mechanical strength and thermo‑mechanical performance of fuel assemblies and fuel elements in the cores of pressurized water (VVER) reactors.

Q: What does it cover?

A: It covers material property requirements, strength and operability criteria for rods and assemblies, calculation methods for static, cyclic and dynamic loads, long‑term effects (creep, fatigue), stability, brittle fracture resistance, load combinations, and experimental validation procedures.

Q: Who typically uses it?

A: Fuel designers, reactor core engineers, safety analysts, testing labs and regulatory reviewers use it for design substantiation, licensing dossiers, safety analyses and experimental program planning.

Q: Is it current or superseded?

A: As listed in official and technical libraries the document is shown as "active" (действует). It was approved by order on 18 January 2016 and came into force on 7 May 2016; recorded actualization entries appear in public catalogs (most recent noted update in source records: 1 January 2021). Users should confirm whether later amendments or newer related national standards have been published when preparing safety‑critical submissions.

Q: Is it part of a series?

A: Yes — NP 094-15 is one of the Federal Norms and Rules (НП) in the area of the use of atomic energy; it is intended to be used together with other NP and national standards addressing nuclear safety, fuel design and calculation practices.

Q: What are the key keywords?

A: Fuel assembly, fuel element, TVS, VVER, strength justification, thermo‑mechanics, fatigue, creep, brittle fracture, dynamic loads, Rostekhnadzor.