TOKYO -- Japan's Onagawa nuclear power plant halted operations on Sunday following a malfunction with measurement equipment within the reactor, local media reported, just days after its first restart since the 2011 disastrous earthquake and tsunami.

The issue arose when a device designed to improve the precision of neutron data readings stopped working partway through installation during testing, the public broadcaster NHK reported, citing Tohoku Electric Power Company.

The power plant unit 2, located in Miyagi prefecture, restarted on Tuesday. Although there was no risk of radiation leakage, Tohoku Electric intended to halt reactor operations for thorough equipment checks.

The timing for the reactor's reactivation remained undecided, NHK reported.

The plant was seriously damaged in the March 11 earthquake and tsunami in 2011, losing most of its external power supply and experiencing flooding in underground facilities.

The reactor cleared safety screening in February 2020 under tougher post-Fukushima crisis safety standards and gained local consent to resume operations.

The Japanese government has been pushing for reactor restarts to help secure energy in the resource-limited nation, though safety concerns about nuclear power persist among the public.

Beyond Onagawa, 12 other reactors across six power plants in central, western and southwestern Japan have resumed operations after meeting stricter safety standards, according to Kyodo News.