What type of valves are pressurizer (PZR) PORV valves in VVER reactors?
Are there different designs depending on the VVER design?
Are they motorized valves powered by alternating current?
We have found that there are also passive PZR valves, are the same valves with two outlets or are they different valves connected by a common pipe?
Dear Professor Queral,
All VVER-1000s (And probably VVER-440s or VVER-1200s) pressurizers are equipped with PSD ( Pulse Safety Device). This equipment has a modular design and contains sub parts including main valve, pilot valves, and an ACL (Additional Control Line for being controlled from MCR or ECR). PSD is a multi-function equipment and can perform its duty both by solenoid or spring. they are totally 3 PSDs installed on the line of PRZ to relief tank. one of them works under control mode (opening-closing at 18.1-17.2 Mpa) and two of them work under safety mode (opening-closing at 18.6-17.7 Mpa).
Dear Prof. Queral,
Alireza's answer is generally correct, of course It should be noted that there are some uncertainties in the PSD's exact operation. For example, the value of PSD opening during control mode is mentioned as 18.1, 18.13, 18.2 and even 18.3 (MPa) in several documents.
In the water-water energetic reactor, or (WER) reactors are Nuclear reactors , Block valves are used and these are Power operated relief and safety valve in Coolant system.The emergency core cooling system also features advanced technologies, and one of them is cold boric acid stored under pressure in special tanks. In case of containment or pipeline rupture, valves open and boric acid is injected into the reactor core to stop the chain reaction and cool down the reactor. ECCS combined with other systems guarantees an extreme degree of the reactor safety.
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