Sellafield nuclear plant workers who falsified records must be "identified and disciplined", says a safety report by the Nuclear Installations Inspectorate.

It said the events exposed by the investigation would not have occurred if there had been "a proper safety culture" within the plant.

Bosses at the Cumbrian plant must "also share responsibility" for the lack of a proper safety culture at the site, it said.

However dismissals will not be forced upon management at the site.

Following the publication of the report BNFL also confirmed it had investigated suspected sabotage at the plant.

'No excuse'

Last September two Mixed Oxide fuel rods were found to contain a small screw and a small piece of solid debris, which the management suspects were placed deliberately by staff.

An investigation failed to identify how the objects had got there, and BNFL said the inquiry has now closed.

Speaking after delivering the report, NII chief inspector Laurence Williams said: "There can be no excuse for process workers not following procedures and deliberately falsifying records to avoid doing a tedious task.

"These people need to be identified and disciplined."

He made three recommendations:

• Deficiencies in the quality checking process must be rectified
  
  
• Plant management must be improved
  
  
• Operators must be replaced or retrained up to HSE standard

BNFL, which runs the plant, said it fully accepted the reports and their recommendations and said actions were already under way to improve the safety culture.

Brian Watson, head of the Sellafield site, said: "BNFL's newly-appointed chairman Hugh Collum is conducting a "fundamental review" of management and will report back to the government within a couple of months.

He added he could not comment on whether any executives would have to resign or be sacked, but said he did not anticipate any further dismissals of process workers.

The NII said "systematic management failure" allowed individual workers to falsify qualify assurance records for reprocessed plutonium bound for Japan.

Poor design of the plant, the tedium of the job and the ease with which the computer dating logging systems was manipulated were all blamed for the problem, which dates back to 1996.

But the report said although data was falsified it would have no effect on the safety of fuel in a nuclear reactor.

The NII, part of the Health and Safety Executive, published three reports into Sellafield - the UK's largest nuclear facility.

BNFL processes spent nuclear fuel from 34 nuclear plants in 9 countries; UK, Japan, Germany, Switzerland, Spain, Sweden, Italy, Netherlands and Canada. Its orders are worth £12bn, of which one third is from overseas customers, mainly Japan.

NII was already carrying out a mini-audit at the site but launched a separate probe when the falsification was discovered.

The plant, which manufactures uranium and plutonium mixed oxide (Mox) fuel rods, has now been shut down. Mr Williams said it will not be reopened until the report's recommendations have been implemented.

In an internal document obtained by the BBC, BNFL admits control of supervision and training of staff involved in the preparation of nuclear fuel was inadequate.

The scandal concerns safety procedures in a new Sellafield factory producing batches of uranium and plutonium mixed-oxide (Mox) fuel rods.

It was discovered that sampling of rods was not carried out and records which showed it had been were copied from previous checks.

Last week the Japanese government demanded a shipment of Mox fuel should be returned to Britain.

BNFL said on Friday it had had a fruitful meeting with the Japanese firm Kansai which had rejected the batch of fuel.

Five workers have so far been dismissed over the scandal - three in October and two more last Tuesday.

The government had been planning to partly privatise BNFL.