Falling Danube shuts two reactor units at Paks nuclear plant, output falls to 25%, Hungary

OAH confirmed that Unit 3 entered shutdown at 15:00 LT on July 29 after operators reduced its output by 237 MW on July 28 and by a further 243 MW the following day. Unit 1 entered shutdown at 05:45 LT on August 1 after its output had first been reduced by 254 MW on July 27, followed by a further 50% power reduction.

The regulator also confirmed a 50% power reduction on Unit 2 from 07:00 LT on July 30 and an identical reduction on Unit 4 from 22:45 LT on July 31.

Hungary’s official water-monitoring network measured the Danube at minus 131 cm (minus 51.6 inches) at Paks at 16:00 LT on August 1. Discharge stood at 745.9 m³/s (26 342 ft³/s), while water temperature near the riverbed reached 27.9°C (82.2°F).

A negative gauge value indicates that the river surface is below the station’s local reference level and does not represent the river’s total depth.

A river forecast issued at 10:36 LT on August 1 placed the Danube at minus 134 cm (minus 52.8 inches), with an uncertainty of plus or minus 4 cm (1.6 inches), at 19:00 LT on August 2 and at minus 135 cm (minus 53.1 inches), with an uncertainty of plus or minus 5 cm (2.0 inches), at 07:00 LT on August 3, indicating that water levels were expected to remain exceptionally low.

Paks draws cooling water from the Danube. Reuters attributed the staged production cuts to the continued fall in river levels following prolonged dry weather, which reduced the amount of water available at the plant’s intake system. Reuters also reported that combined generation had fallen to about 25% of the station’s 2 000 MW capacity.

Prime Minister Péter Magyar said a complete shutdown could become necessary if the river continued to fall.

According to AP, the plant would have to shut down completely if the gauge reached minus 134 cm (minus 52.8 inches). The same report said the previous minimum at Paks was minus 98 cm (minus 38.6 inches), recorded in 2018, although that historical comparison could not be independently verified from an official gauge archive reviewed for this article.

Paks normally supplies nearly half of Hungary’s electricity. Reuters reported that large industrial consumers had already committed about 240 MW of voluntary demand reductions, while the government authorized grid operator MAVIR to order mandatory industrial cuts if domestic production and imports proved insufficient. The report also said the possible return of approximately 400 MW from the Százhalombatta gas-fired power plant could help offset part of the lost nuclear generation.

OAH said the production changes were implemented in accordance with operating requirements that do not concern nuclear safety. The regulator said the shutdowns and power reductions had no adverse effect on nuclear safety or the environment and that it continued to supervise the condition of all four reactor units.

References:

¹ További leterhelés a Paksi Atomerőműben – Országos Atomenergia Hivatal – August 1, 2026

² Vízállás-előrejelzés [cm] – Országos Vízjelző Szolgálat – August 1, 2026

³ Hungary braces for a full shutdown of the Paks nuclear plant as the Danube River hits record lows – AP – July 31, 2026

⁴ Hungary’s Paks nuclear plant could be powered down this weekend, PM says – Reuters – August 1, 2026