Devonport naval dockyard sent radioactive waste to the UK’s nuclear disposal site in Drigg, Cumbria, throughout the early 1990s that breached the facility’s annual legal limits, it emerged this week.
In four separate years 1990, 1991,1994 and 1995 drums full of ion-exchange resins from nuclear submarines were sent to Drigg. Each consignment contained higher levels of radioactive Carbon 14 than Drigg was allowed to accept from all sources in any given year.
The Environment Agency may now require DML, which owns the yard, to take back the drums now sealed in buried containers to remove the isotope.
In the worst instance in 1990, Devonport consignments contained 228.3Gbq of C14 radioactivity against Drigg’s authorised annual limit of 50Gbq.
Reg Shield, sales and marketing manager at DML, said that C14 was ‘historically’ not listed as one of the radioactive isotopes that Devonport was required to identify specifically in its shipments to Drigg.
Earlier this year, the company reassessed the C14 levels of past shipments on the basis of 17 samples taken from a single submarine and came up with the alarmingly high levels.
Shield said, however, that the total radioactivity of the consignments had been specified at the time and stressed that there was no risk to health.
British Nuclear Fuels, which operates Drigg, is concerned that other shippers may not have identified CI4 or other isotopes for which the site has annual limits and is conducting a full investigation.
‘Clearly there remains a question mark,’ said a company spokesman at BNFL’s Sellafield site.
John Large, a nuclear consulting engineer, said that the revelation cast serious doubts over the BNFL operation: ‘It makes a mockery of quality control at Drigg.’
The Environment Agency, which issues Drigg’s authorisations, has stopped all shipments to the site from Devonport. It has also asked DML to carry out further assessments on the C14 content of the consignments.
Shield said DML was willing to take the drums back if necessary. ‘If the regulator ultimately decides that the C14 has to removed, it can be done,’ he said.