Bangladesh’s Rooppur 1 Reactor Reaches First Criticality

Bangladesh’s first nuclear reactor went critical on Sunday evening, with Unit 1 of the Russian-built Rooppur Nuclear Power Plant achieving a self-sustaining chain reaction at 15:34 local time on 11 October, project officials said. The milestone, confirmed in a statement from the plant’s official account and reported by World Nuclear News citing Rosatom’s in-house outlet Strana Rosatom, puts South Asia’s newest nuclear newcomer on track for a planned grid power start-up on 20 November.

Criticality came three days after Bangladesh’s atomic regulator cleared the unit to start its first controlled chain reaction, a decision that had been held up by a technical issue with the reactor’s automatic pressure-relief safety valves. The regulator’s chairman said at the time that two further approvals would still be needed before Unit 1 can formally begin supplying power to the national grid.

What happens between criticality and first power

Reaching criticality does not mean the plant is generating electricity. Rosatom’s own project timeline calls for a sequence of tests and inspections to confirm that reactor systems behave as designed, followed by operation at minimum controllable power — the lowest stable output level at which the reactor can be monitored and adjusted. Only after those checks will operators begin raising output in stages toward the planned 20 November start-up, with grid supply advancing step by step as each test clears.

The plant’s own statement framed the achievement as a milestone for “Bangladesh’s technological advancement and energy security” and said the facility will help diversify a power system that leans heavily on imported and domestic natural gas. Rosatom said separately that its automation subsidiary had finished installing process control systems at both Unit 1 and Unit 2, and that director general Alexey Likhachev met Bangladesh’s science and technology minister, Fakir Mahbub Anam, in Moscow the Friday before criticality was reached.

A decade-long build now in its final stretch

Rooppur’s two VVER-1200 pressurised water reactors trace back to a February 2011 intergovernmental agreement between Dhaka and Moscow, formalised in a December 2015 construction contract worth $12.65 billion — one of Rosatom’s largest single export orders. A site licence followed in June 2016, and construction of Unit 1 began in November 2017, with Unit 2 following in July 2018. Both units are designed for an initial 60-year operating life, extendable by a further 20 years.

The project has moved through its commissioning milestones over the past three years: first fuel arrived at the site in October 2023, turbine installation was completed in March 2025 ahead of hydraulic and hot functional tests, and the 163 fuel assemblies that make up Unit 1’s core finished loading in May 2026. An operating licence for the unit was issued by Bangladesh’s nuclear regulator on 16 April 2026, clearing the final regulatory hurdle before this week’s criticality milestone. The plant sits roughly 160 km from Dhaka.

Why a gas-reliant grid is watching closely

Rooppur’s start-up lands at a moment when Bangladesh’s power system is under real strain. Natural gas — much of it imported — still accounts for roughly 40-45% of generation, according to Bangladesh Power Development Board data compiled by the Centre for Policy Dialogue, with some independent trackers putting gas’s generation share closer to 60%. Declining domestic reserves have pushed the country further toward LNG imports just as the Strait of Hormuz crisis has disrupted tanker traffic: industry estimates suggest roughly two-thirds of Bangladesh’s LNG supply in 2025 moved through the strait, and cargo volumes fell sharply over the summer as attacks on shipping in the waterway escalated. Power shortfalls this year have at times reached close to a fifth of demand on a 32 GW grid, forcing load-shedding during peak-demand months.

Against that backdrop, Rooppur’s roughly 2,400 MW of combined capacity across two units represents one of the few large, non-gas additions to Bangladesh’s generation mix in the pipeline. It also makes Bangladesh the latest member of Rosatom’s export client list to reach this stage, following a similar sequence at Turkey’s Akkuyu plant, where Unit 1 cleared hydraulic tests earlier this month, and at China’s Tianwan site, where Unit 7 reached minimum controllable power on its way to commercial operation — a track record Moscow has leaned on heavily to market VVER technology to new nuclear states. A fuller history of Turkey’s project is tracked on The Daily Energy’s Akkuyu project tracker.

What comes next

The near-term calendar is now set by Rosatom’s own schedule: a controlled rise to minimum power, further safety testing, and a targeted first grid connection around 20 November. Bangladeshi officials have previously floated a window for trial power supply by late December, though regulators have stressed that each stage depends on the previous one clearing its tests. Unit 2, following roughly eight months behind Unit 1 in construction, is expected to pass through the same sequence of milestones over the coming year.

Sources:

• World Nuclear News, “Bangladesh’s Rooppur 1 achieves criticality,” 12 October 2026 — criticality timing, regulatory sequence, project history, official quotes.
• bdnews24, coverage of BAERA’s 8 October approval for first criticality — regulatory delay and remaining approval steps.
• Centre for Policy Dialogue (CPD) / Bangladesh Power Development Board data, August 2026 — generation mix figures.
• Zero Carbon Analytics and IEEFA analyses, 2026 — gas-generation share, LNG import disruption through the Strait of Hormuz, grid shortfall figures.

Illustrative image. Photo: A.Savin, CC BY-SA 3.0, via Wikimedia Commons — source