Nuclear safety class equipment refers to structures, systems and components classified according to how severely their failure would affect plant safety. The NP-001-15 rules used for Russian-designed plants define four classes from 1 to 4: Class 1 covers the most critical parts such as the reactor vessel, and Class 4 covers normal operation equipment that does not affect safety.
What is the classification based on?
The basic principle is the graded approach: the more serious the consequences an item's failure could have, the stricter its design, manufacture and inspection. The International Atomic Energy Agency's SSG-30 guide recommends at least three safety classes for structures, systems and components important to safety; the rest are considered not important to safety. The Russian NP-001-15 rules use four classes; this system appears in the documents of VVER projects such as Akkuyu.
In Türkiye, classification is part of the licensing file. Under the Regulation on Authorisations for Nuclear Facilities (Nükleer Tesislere İlişkin Yetkilendirmeler Yönetmeliği), the sections of the Safety Analysis Report containing the classifications of structures, systems and equipment are submitted to the Nuclear Regulatory Authority (Nükleer Düzenleme Kurumu, NDK) with the site preparation permit application.
The four classes under NP-001-15
| Class | Scope | Example |
|---|---|---|
| 1 | Items whose failure could cause fuel damage beyond design limits even if the safety systems operate | Reactor pressure vessel, primary circuit pressure boundary, fuel elements |
| 2 | Items whose failure could cause fuel damage without exceeding design limits, and elements of safety systems | Such as pumps and valves of emergency cooling systems |
| 3 | Items important to safety that do not fall into the first two classes | Some auxiliary systems containing radioactive media, monitoring systems |
| 4 | Normal operation items that do not affect safety | General installations in the turbine building, amenity building equipment |
The definitive class is read from the project's classification list. The same type of pump may be Class 2 in one system and Class 4 in another. According to Akkuyu Nükleer, the polar crane in the reactor building is also in the highest safety class; this example shows that the class is not limited to pressure equipment.
How does the class affect procurement?
- Manufacturer competence: In the higher classes, the manufacturer is expected to have a nuclear quality programme approved by the project owner. Article 7 of Nuclear Regulatory Law No. 7381 (7381 sayılı Nükleer Düzenleme Kanunu) authorises the NDK to inspect the activities of contractors, subcontractors, suppliers and sub-suppliers as well.
- Conformity assessment: Hold and witness points involving the customer and independent bodies are defined in manufacturing; the next step cannot begin until these points are approved.
- Document set: Material certificates, test protocols and the equipment passport travel with the part; a part with incomplete documents is not accepted on site.
- Commercial products: The amendment of 2 October 2026 defined components not designed and manufactured under nuclear regulations but performing a function important to safety as "commercial products" (hazır ürün). Before such a commercial product is procured, the licensee verifies its conformity with the documents and technical requirements through inspection, testing or analysis and obtains the NDK's favourable opinion for its use.
What changes in logistics?
The class is also reflected in the transport specification: packaging type, moisture and shock protection, storage level and documents travelling with the cargo. Details are explained in how the safety class affects transport conditions. A part being Class 1 does not make it radioactive; newly manufactured equipment is carried under general cargo rules and does not fall under the radioactive material regime. Getting it to site falls under the discipline of nuclear project transport.
Common mistakes
- Not stating the equipment's class and code on the shipping document.
- Shipping parts of different classes in the same crate without separate labels.
- Shipping with a scanned copy of the certificate instead of the original.
- Sending a commercial product to a system with a safety function without qualification.
Frequently Asked Questions
Are safety class and seismic category the same thing?
Where can you find the safety class of a piece of equipment?
Sources
- 7381 sayılı Nükleer Düzenleme Kanunu (Nuclear Regulatory Law No. 7381, Art. 7)
- Official Gazette (Resmî Gazete) 02.10.2026 – Amendment to the Regulation on Authorisations for Nuclear Facilities
- Akkuyu Nükleer – Polar crane for Unit 1 delivered to Akkuyu NPP construction site
- IAEA SSG-30 – Safety Classification of Structures, Systems and Components in Nuclear Power Plants