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Imperiled Ukrainian nuclear power plant has the world on edge – a safety expert explains what could go wrong

The Conversation, Najmedin Meshkati, 26 Aug 22, “…………………………………… What are the risks to a nuclear plant in a conflict zone?

Nuclear power plants are built for peacetime operations, not wars.

The worst thing that could happen is if a site is deliberately or accidentally shelled. If a shell hit the plant’s spent fuel pool – which contains the still-radioactive spent fuel – or if fire spread to the spent fuel pool, it could release radiation. This spent fuel pool isn’t in the containment building, and as such is more vulnerable.

Containment buildings, which house nuclear reactors, are also not protected against deliberate shelling. They are built to withstand a minor internal explosion of, say, a pressurized water pipe. But they are not designed to withstand a huge explosion.

As to the reactors in the containment building, it depends on the weapons being used. The worst-case scenario is that a bunker-buster missile breaches the containment dome – consisting of a thick shell of reinforced concrete on top of the reactor – and explodes. That would badly damage the nuclear reactor and release radiation into the atmosphere, which would make it difficult to send in first responders to contain any resulting fire. It could be another Chernobyl.

What are the concerns going forward?

The safety problems I see are twofold:

1) Human error……….

2) Power failure

The second problem is that the nuclear plant needs constant electricity, and that is harder to maintain in wartime.

Even if you shut down the reactors, the plant will need off-site power to run the huge cooling system to remove the residual heat in the reactor and bring it to what is called a cold shutdown. Water circulation is always needed to make sure the spent fuel doesn’t overheat.

Spent fuel pools also need constant water circulation to keep them cool, and they need cooling for several years before they can be put in dry casks. One of the problems in the 2011 Fukushima disaster in Japan was the emergency generators intended to replace lost off-site power got inundated with water and failed. In situations like that, you get “station blackout” – and that is one of the worst things that could happen. It means no electricity to run the cooling system.

In that circumstance, the spent fuel overheats and its zirconium cladding can create hydrogen bubbles. If you can’t vent these bubbles, they will explode, spreading radiation.

If there is a loss of outside power, operators will have to rely on emergency generators. But emergency generators are huge machines – finicky, unreliable gas guzzlers. And you still need cooling waters for the generators themselves.

My biggest worry is that Ukraine suffers from a sustained power grid failure. The likelihood of this increases during a conflict because power line pylons may come down under shelling, or gas power plants might get damaged and cease to operate. …………………….

How else does a war affect the safety of nuclear plants?

One of the overarching concerns about the effects of war on nuclear plants is that war degrades safety culture, which is crucial in running a plant……………………..

War adversely affects safety culture in a number of ways. Operators are stressed and fatigued and may be scared to death to speak out if something is going wrong. Then there is the maintenance of a plant, which may be compromised by lack of staff or unavailability of spare parts.

Governance, regulation and oversight – all crucial for the safe running of a nuclear industry – are also disrupted, as is local infrastructure, such as the capability of local firefighters. In war, everything is harder……………..  https://theconversation.com/imperiled-ukrainian-nuclear-power-plant-has-the-world-on-edge-a-safety-expert-explains-what-could-go-wrong-189429

August 26, 2022 - Posted by | safety, Ukraine, weapons and war

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