The move came out of a meeting Wednesday between Japanese nuclear experts, government members and professors, CNN reported.
NISA presented a draft report to the meeting that approved stress tests performed on reactor No. 3 and No. 4 at the Kansai Electric Power Co.'s Oi plant.
Kansai Electric said the stress tests show the two reactors are capable of withstanding an earthquake 1.8 times more powerful than the maximum estimated quake for the region, as well as a tsunami 37 feet high.
For the reactors to be restarted, the tests must also be reviewed by the Nuclear Safety Commission and the International Atomic Energy Agency. The government and local communities will then decide whether the plant will be brought back into operation.
The meeting marks the first time officials met to discuss the restart of Japan's nuclear plants since last year's Fukushima disaster, CNN reported.
Protesters delayed the meeting for several hours because private citizens were not allowed to attend, Kyodo News reported.
"They shut out the citizens," said Ayako Sakine, a Greenpeace member who was involved in the protest. "This is unforgivable."
Industry minister Yukio Edano said it was "totally unacceptable" for the protesters to interfere with a scientific discussion on reactor safety issues.
A monitor with a live-feed of the meeting was made available for public spectators in another room.