What are the risks faced by Zaporizhzhya, the nuclear power plant in a war zone?
- July 6, 2023
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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What are the risks faced by Zaporizhzhya, the nuclear power plant in a war zone?
Subject: International Relations
Section: Places in news
Context:
- In June, a Lithuania-based NGO named the Bellona Foundation published a report, analysing the risks associated with the hostilities around, near, or at the Zaporizhzhya NPP, based on the facility’s design, safety measures, and the local geography.
What is the reactor design at Zaporizhzhya?
- Zaporizhzhya NPP is located southwest of Zaporizhzhia city, along the Dnieper River.
- It has six VVER-1000 reactors providing a total power-generation capacity of 6 GW.
- The reactor complex consists of the reactor vessel, in which fuel rods are submerged in water.
- Control rods are inserted at the top.
- The water acts as both coolant and moderator.
- A pressuriser holds the water at a high but constant pressure (around 150 atm) to prevent it from boiling. This is the primary cooling circuit.
- As the water heats up, the heat is moved to a secondary cooling circuit, where it converts a separate resource of water into steam. This steam is fed to turbines that generate electricity.
- In this design, the primary coolant and the moderator are the same substance (water), and it doesn’t leave the reactor vessel at any time.
Is Zaporizhzhya comparable to Chernobyl?
- The report says that any damage to the Zaporizhzhya NPP is unlikely to play out in the same fashion or at the same scale.
- The principal difference between Chernobyl and Zaporizhzhya is that the former had RBMK reactors and the latter has VVER-1000 reactors (this is the same reactor design installed at the Kudankulam NPP in India).
- Zaporizhzhya also takes advantage of safety measures installed in the aftermath of the Chernobyl and Fukushima disasters.
- In RBMK reactors like at Chernobyl, the coolant and the moderator are different (light water and nuclear graphite, respectively). And the coolant, which is radioactive from having been exposed to the nuclear fuel, flows out of the reactor vessel.
- One of the reasons Chernobyl was so bad is that when the reactor was breached, the superhot graphite caught fire when it came into contact with air.
- Unlike Chernobyl, the VVER-1000 reactor and its power-generation units at Zaporizhzhya are also placed inside a large airtight chamber called a containment. Its walls are 120-cm thick and made of pre-stressed concrete.
Risk factors:
- The principal danger here is that the primary water circuit could depressurise as steam and escape into the air, along with radioactive material and other volatile substances.
- This mixture will contain the isotope iodine-131, which is easily dispersed by winds and accumulates in and damages the thyroid gland in humans. It has a half-life of around eight days and so it would only pose a threat for several weeks.
- A breach and depressurisation would also release caesium-137, which has a half-life of 30 years and was responsible for contaminating much of Chernobyl’s surroundings after the accident.
Report recommendations:
- On June 6, 2023, the Kakhovka dam, which is downstream of the Zaporizhzhya NPP and in whose reservoir the plant is located, was breached.
- The Bellona report suggested that the walls of the pond were built to withstand a water-level differential of 6 metres.
- After considering the possibility of this breach as well, the report made the following recommendations (reworded):
- All reactors should be in shutdown or cold-shutdown states
- There should be no effort to move fuel at the same time as hostilities around the plant
- Hostilities should be kept out of the territory of the plant itself
- If/when Russian troops withdraw from the plant, plant staff should be rehabilitated
Kudankulam Nuclear Power Plant:
- Kudankulam NPP or KKNPP is the largest nuclear power station in India, situated in Kudankulam in the Tirunelveli district of the southern Indian state of Tamil Nadu.
- Construction on the plant began on 31 March 2002, but faced several delays due to opposition from local fishermen.
- KKNPP is scheduled to have six VVER-1000 reactors built in collaboration with Atomstroyexport, the Russian state company and Nuclear Power Corporation of India Limited (NPCIL), with an installed capacity of 6,000 MW of electricity.