The Telegraph reported that five years back the plant operator was asked to check its data after it admitted that temperature readings for coolant materials had been falsified way back in 1985.
Radiation levels spiked Tuesday after blasts and a fire at reactors in the quake-damaged nuclear plant in northeastern Japan. A government spokesman said the radiation was high enough to affect human health.
The plant's operator, the Tokyo Electric Power Co (TEPCO), said it feared the reactor containment vessel had been damaged in an explosion in reactor number 2 at Fukushima, home to six nuclear reactors.
A fire was reported Tuesday in reactor 4. Hydrogen explosions rocked reactors 1 and 3 Saturday and Monday, sparking fears of reactor meltdowns.
Persistent probles have dogged the plant.
In 2002, TEPCO's president Nobuya Minami and some senior officials quit in disgrace after the Japanese government disclosed that at least 29 cases of cracks and other damage to reactors had been covered up.
The scandal was regarding three nuclear sites including Fukushima's number 1 and number 2 plants. Besides the incident at Fukushima, four workers at the Mihama nuclear power plant were killed four years back when steam escaped from a broken pipe, the media report said.
Over a decade back, in 1999 two workers died of radiation poisoning at a nuclear processing plant accident in Tokaimura. An accident had taken place at the Tsurugura nuclear power plant in the north of Japan and a fire broke out at the Monju reactor in central Japan in 1995.