Safety classes of NPP elements

Safety classes of NPP elements

The basics of NPP safety and general requirements for them are regulated by international standards of the IAEA and the Federal Service for Environmental, Technological and Nuclear Supervision., The division into safety classes of NPP equipment was developed on their basis. The clear instructions are spelled out in the norms and rules for the use of nuclear energy No. NP-068-05, 001-15, 026-16, 089-15.

Equipment classification method by safety degree

NPP equipment classes are assigned depending on the degree of their impact on safety. Calculations are made to prevent overestimation of the class and, as a result, to reduce the cost of equipment. So, for example, if instead of 4, the 3rd safety class of NPP equipment is assigned, its price may increase by a quarter. Often these are millions of rubles.

Classification includes mandatory items:

  • Compliance with international and Russian standards.
  • Assignment of class to equipment and structures.
  • Risk-informative classification and indicators of its significance.
  • Calculation of probability of severe accident in case of element failure.

The main safety functions of NPP are the ability to control reactivity. This is the activation of the emergency reactor installation and ensuring its subcriticality, heat removal from the nuclear reactor, prevention of the release of radioactive substances, radiation control. These are fundamental security standards that apply to all countries.

Security classes

NPP equipment from the point of view of safety is divided into important and non-affecting. This is the equipment of protective systems (preserving the integrity of the pipes and the reactor shell), localizing systems (containment, containment), providing (water supply, power supply, ventilation), control (blocking, alarm, automation).

There are 4 classes of safety of NPP equipment:

  1. Fuel elements and reactor vessel.

Initial accident event exceeding the design value. Elements, when leaving which there is a disturbance in the operation of fuel elements, the main structural units of the reactor. This includes the risk of depressurization of fuel elements, violation of integrity and the occurrence of a beyond design basis accident.

  1. Emergency cooling systems, RCC, steam generators, pressurizers, unloading system, pipeline, emergency water supply, etc.


Elements, failure of which will be considered the initial event in case of damage to 1 and 2 physical barriers: fuel matrix, coolant shell. Unlike the first class, the maximum attached project is not exceeded.

  1. Water daerization, bypass treatment system.

Safety class 3 of NPP equipment — elements not included in the first 2 classes. Failure of such equipment entails release of radioactive substances into the atmosphere, violation of the maximum permissible level of radiation.

  1. Equipment with no signs of classes 1-3 and which does not affect safety.

If several classes are detected in the equipment, it is referred to the higher class of NPP equipment.

Safety class is assigned at the power unit design stage according to the TKP-170-2009. The higher the class, the stricter the requirements for the quality, strength and diagnostics of the nuclear power plant equipment.

Features of supply and manufacture of elements for NPP

If the equipment offered for sale belongs to safety class 1-3, then its documentation must contain an alphanumeric value.

Abbreviation based on purpose:

  • H — normal operation.
  • H — protection.
  • L — localization.
  • O — Security.
  • Y — management.

Numbers — class, letter — purpose. So with several assignments, all of them are indicated. For example, isolation valves 1A, 2BII, 2BIII.

Support of suppliers of services and equipment in the field of nuclear energy

Technical Decision Group provides advisory services for enterprises operating in the energy industry. High-quality support and supervision of projects at any stage of implementation.

Customers of the company receive:

  • Development and examination of technical documentation.
  • Support during product testing, service quality control.
  • Audit, diagnostics of NPP equipment, quality control system.
  • Comprehensive support and certification assistance.

Quick training of personnel, trainings, familiarization with the requirements and standards of the Russian Federation. Site selection, bid and contract for equipment, raw materials or services.

If you are interested in nuances or have difficulties with equipment safety classes, contact. We are competent in this matter, have a lot of practice under our belt and will share our experience with you. Leave a request on the site and we will try to give feedback as quickly as possible.

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