{"id":31815,"date":"2026-06-26T13:33:30","date_gmt":"2026-06-26T11:33:30","guid":{"rendered":"https:\/\/www.revistanuclear.es\/?p=31815"},"modified":"2026-06-26T13:33:32","modified_gmt":"2026-06-26T11:33:32","slug":"innovations-in-valves-for-nuclear-safety-in-pwrs","status":"publish","type":"post","link":"https:\/\/www.revistanuclear.es\/en\/safety\/innovations-in-valves-for-nuclear-safety-in-pwrs\/","title":{"rendered":"Innovations in valves for nuclear safety in PWRs"},"content":{"rendered":"
\"\"<\/span>SEE FULL VERSION<\/span><\/a>
<\/div>V<\/span>irtually all PWR reactors worldwide have passive safety features called accumulators. These are tanks filled with borated water and pressurized with high-pressure nitrogen (\u224845 bar) and connected to the RCS via non-return valves. During a LOCA (Loss of Cooling Accident) when the RCS pressure drops below the nitrogen pressure, this water is passively injected into the reactor to replenish the accumulator. This works perfectly for a time. However, once the water is depleted, propellant nitrogen will enter the RCS, triggering a series of complications that will jeopardize core cooling.<\/span><\/p>\n

Currently, plants have emergency procedures in place to try to prevent this undesired nitrogen injection (FSG-10). These procedures rely on operators detecting the depletion of the accumulators and attempting to close the isolation valves on time. \u00a0\u00a0<\/span><\/p>\n

However, during a total loss of electrical power accident (LTSBO) like Fukushima, with the complete loss of control of the equipment, there is a high probability that the nitrogen in the accumulators will end up in the RCS (Reactor Coolant System). Even without a loss of electrical power, injection could occur if any of the valves involved do not close properly and in time, or if they leak internally. It’s important to remember that these valves are designed to open and remain open, and that they are de-energized and disconnected 99.99 % of the time. They are not leak-tested because their safety function is to remain open.<\/span><\/p>\n

Faced with this problem, an employee of a Spanish nuclear plant designed a new type of valve, solving this problem automatically and passively: the ASVAD Valve<\/strong>. Unlike isolation valves, it uses the strategy of depressurizing the accumulator and releasing the residual nitrogen into the containment atmosphere.<\/span><\/p>\n

\"Estructura