ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
2025 ANS Winter Conference & Expo
November 8–12, 2025
Washington, DC|Washington Hilton
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
Latest Magazine Issues
Oct 2025
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
December 2025
Nuclear Technology
November 2025
Fusion Science and Technology
Latest News
Illinois legislature lifts ban on nuclear energy, funds clean energy
The Illinois General Assembly passed a clean energy bill on October 30 that would, in part, lift a 30-year moratorium on new nuclear energy in the state and create incentives for more energy storage.
Seyed Ali Hosseini, Alireza Najafi, Amir Saeed Shirani, César Queral, Francesco D’Auria
Nuclear Technology | Volume 211 | Number 3 | March 2025 | Pages 607-623
Note | doi.org/10.1080/00295450.2024.2337313
Articles are hosted by Taylor and Francis Online.
Hydro-accumulators, as a passive part of the emergency core cooling system, have been upgraded in different types of VVER-1000s. The number and performance of these systems are modified in newer types of VVER-1000s to operate at different pressures and flow rates. The VVER-1000/446, as a distinguished design from the old generation (VVER-1000/320), utilizes two stages of hydro-accumulators. The second-stage accumulators (SSAs) are dedicated to improving the performance of the VVER-1000/446 under design extension conditions (DECs) and delaying the onset of core damage. During the upgrading of the VVER-1000/446, some orifices have been embedded as flow restriction components (FRCs) on the injection line of the SSAs to increase the water injection time during DECs.
This paper aims to assess the performance of the SSAs according to their orifice diameter changes during median-break (MB)– and large-break (LB)–loss-of-coolant accidents (LOCAs). Several cases of FRC arrangements were investigated to demonstrate the core damage times during MB-LOCA (200-mm break) and LB-LOCA (400-mm break) scenarios. The results show that although the current size of the installed FRCs on the VVER-1000/446 is quite suitable for the MB-LOCA, it is not a proper choice for the LB-LOCA. Therefore, this demonstrates that the core damage time is highly dependent on the FRC size arrangement.
This paper indicates an arrangement of FRCs that can modify the plant’s response in both MB and LB LOCAs without active injections. Therefore, as an additional finding, the sequential arrangement of FRCs can increase plant resilience against a broad range of LOCAs without operating active emergency cooling systems.