Heatwave in Europe exposes N-power's water vulnerability; Indian analyst warns against reactor expansion

As Europe grapples with an unprecedented summer heatwave, the fragility of nuclear power's dependence on water cooling has been laid bare — with 13 French reactors forced offline and similar shutdowns rippling across Hungary, Romania, and beyond. The crisis has prompted a stark warning from Indian power and climate policy analyst Shankar Sharma, who argues that if such failures can occur in Europe's relatively cooler climate, the risks for water-stressed India are orders of magnitude higher.

"Yet another reason as to why our authorities should exercise extreme care before committing our country to the unacceptable costs and risks associated with multiple additional nuclear power plants", he underlines.

France: 20% of Nuclear Capacity Offline

The combined effects of the heatwave and drought have forced 13 French nuclear reactors offline, representing 20.4% of the country's nuclear generating capacity, according to an AFP analysis based on data from French state-owned utility EDF. The shutdowns, attributed to "environmental constraints" or "external environmental factors," mark the highest level recorded since 2015. 

EDF expects output to decline at the Blayais, Bugey, Cattenom, Chooz, Golfech, Gravelines, and Saint-Alban nuclear power plants over the coming days. Current forecasts indicate that weather conditions could result in a maximum capacity loss of 12,474 MW between August 14 and September 1.

Real-time monitoring data from grid operator RTE show nuclear output at around 32 GW on the morning of Friday, August 14, compared with approximately 45 GW on a typical day in March. 

Solar Steps In as Nuclear Falters

While nuclear reactors struggled, solar generation has remained exceptionally strong for several weeks, accounting for up to 35% of France's electricity generation mix. 

The trend extends across Europe. A study published on August 13 by energy think tank Ember found that solar generation has been running above normal levels across several European countries during recent heatwaves.

"As demand rises and other energy sources struggle, solar is the only electricity source with output exceeding normal levels: up 17% daily in France and Hungary, and 5% in Spain and Italy," Ember reported. 

Ember analyst Chris Rosslowe noted: "The rise in solar power generation helped stabilize the grid at a time when other energy sources were struggling to operate normally." 

The Crisis Spreads: Hungary, Romania, UK, and Italy

France is not alone. The vulnerability of thermal and nuclear plants to heat and drought is exposing systemic weaknesses across the continent:

- Hungary: The Paks nuclear power plant, which supplies nearly half of the country's electricity, sharply reduced output in early August because of exceptionally low water levels in the Danube. 

- Romania: Low water levels in the Danube — Europe's second-longest river — have forced authorities to consider stopping the country's nuclear power plant, which relies on river water for cooling. 

- United Kingdom: Five gas-fired plants have cut production due to heat-related constraints.

- Italy: Low water levels in the Po River have threatened the operation of thermal power plants in the northeast.

- Serbia and Poland: Coal-fired plants have also had to scale back operations.

Hydropower has not been spared either. Seven of the European Union's eight largest hydropower producers, accounting for 90% of the bloc's total hydroelectric output, recorded generation below their five-year averages. 

The Evening Challenge: Batteries Needed

While solar has proven resilient during daylight hours, the main challenge emerges after sunset. During heatwaves, demand remains high — driven largely by air conditioning — while photovoltaic generation falls to zero. The grid must then rely more heavily on dispatchable sources, including gas-fired power plants.

"The challenge with solar energy begins after sunset," Rosslowe said. 

Battery storage is increasingly seen as the bridge solution. Ember argues that storing electricity generated during the day and releasing it in the evening could reduce reliance on the most expensive thermal generation.

"Solar power helps us during the day, but battery storage can take over in the evening. Together, they represent one of the cleanest ways to make the European electricity system more resilient during the hottest summers," Rosslowe added. 

During the heatwaves in late June and early July, average daily electricity prices increased by 119% in Hungary, 44% in France, 13% in Italy, and 7% in Spain compared with preceding weeks. 

Sharma's Warning for India

Shankar Sharma, a Power & Climate Policy Analyst based in Sagara, Karnataka, with over 38 years of experience in the power sector across India and Australia, draws a direct line from Europe's crisis to India's precarious position. 

"If such an alarming scenario of cooling water supply to nuclear reactors can occur in the relatively cooler climate of Europe, the probabilities of such a scenario in India can be projected as credible; in the context that the heatwave days and spread in the country are increasing with the passage of each year", says Sharma.

India is already one of the top seven most water-stressed countries in the world, according to global assessments. The country's rivers, reservoirs, and groundwater aquifers are under severe pressure from agriculture, industry, and a growing population. Adding numerous nuclear reactors — each requiring enormous volumes of cooling water — into this equation, Sharma argues, is a recipe for compounding disaster.

The timing is particularly critical. India is simultaneously planning a massive expansion of data centres, which are notoriously water-intensive for cooling, further straining an already depleted water resource base.

"Hence, extreme due diligence must precede any potential decision to set up additional nuclear reactors in the country, which is already one of top 7 most water stressed countries with the plans to set up numerous data centres too", he adds.

A Pattern of Concern

Sharma has been a consistent voice urging India's policymakers to look beyond conventional large-scale energy infrastructure. In previous communications to the Prime Minister's Office, NITI Aayog, and various ministries, he has highlighted the unsustainable trajectory of India's material and energy consumption, noting that the country's material use is projected to more than double by 2030. 

He has also criticized the absence of a cohesive national energy policy and warned that India's continued reliance on coal, hydro, and nuclear projects — alongside large-scale solar and wind farms — is accelerating environmental devastation. 

Conclusion

The European summer of 2026 has delivered a real-world stress test of nuclear power's dependence on stable water supplies and moderate temperatures. With 13 French reactors offline, Hungary's Paks plant curtailed, and Romania's nuclear facility under threat, the evidence is mounting that nuclear energy — long marketed as a reliable baseload source — is acutely vulnerable to the very climate change it is supposed to help mitigate.

For India, where heatwaves are intensifying, water scarcity is deepening, and the demand for electricity is surging, Sharma's warning carries particular urgency. The question, he suggests, is not whether India can afford to slow its nuclear ambitions — but whether it can afford not to.