Chashma Nuclear Power Plant Unit-1 has completed 427 consecutive days of operation during its 18th operating cycle, setting a record for the longest continuous cycle in the Pakistan Atomic Energy Commission’s history.
Associated Press of Pakistan reported the achievement on September 24, citing PAEC’s announcement.
The record at a glance
| Detail | Information |
|---|---|
| Nuclear unit | Chashma-1, also called C-1 |
| Continuous operating period | 427 days |
| Operating cycle | Cycle 18 |
| Gross generating capacity | 325MW |
| Operator | Pakistan Atomic Energy Commission |
PAEC’s nuclear power information page lists C-1 among the four operating reactors at the Chashma site and states that the unit began operation in 2000.
What does 427 days of operation mean?
The announcement concerns how long an existing reactor operated continuously. It does not mean that Pakistan added 325MW of new generating capacity.
It also should not be interpreted as proof that the reactor produced its maximum rated output every hour. Operating duration, generating capacity and actual electricity production are different measures.
PAEC also reported that C-1 achieved a World Association of Nuclear Operators Performance Indicator Index score of 100 in each of the first two quarters of 2026.
How C-1 fits into Pakistan’s nuclear fleet
PAEC lists six operating nuclear power plants with a combined capacity of 3,530MW. Four are at Chashma and two are at Karachi.
A separate project, Chashma-5, concerns additional capacity. Readers can find background in our report on the Pakistan–IAEA safeguards agreement for Chashma-5.
The distinction matters: C-1’s latest milestone measures the performance of an operating unit, while C-5 is a separate nuclear power development.
For an update on the site’s operating fleet, read about Chashma-1’s 427-day continuous operating record.
