Annual Report for 2010/11 and Forward Programme - Sellafield Ltd

SSEM/2011/4730 June 2011wear gloves during retrievals that are removed by correct practice after objects have beenretrieved. Operators do not put hand to mouth/face during retrievals while wearing gloves.The wetting process in retrieval prevents blown material that could be inadvertently ingested.5.3.4 Skin contact and woundsSkin dose is dependent on activity of an object and its time in contact or in close proximitywith the skin. Operators not only take precautions while retrieving objects but once a retrievalis complete (with objects sealed in containers), operators self check with contaminationmonitoring instruments to determine whether activity has become attached to their person,thus eliminating the potential for any prolonged contact should it occur. Consequently, thereis extremely low potential for skin dose during operations.Entry of material into the body via wound sites is a well recognised potential. Operators arewell versed in practices to seek and cover any wound site prior to working with radioactivematerials. In addition, use of gloves and standard work clothing mitigate against any intakevia wound sites.5.3.5 Reassurance by monitoring for internal uptakeEven though potential is low for intake and uptake of material into the body, a regime ofinternal dosimetry is provided for each operator. This involves monthly provision of sampleswith analysis on a quarterly basis but with stored samples for further analysis should anyuptake be suspected. For operations to date there has not been a dose uptake by anyoperator.5.3.6 Potential of exposure to the publicThe HPA reports cover the period of 3 years between the summers of 2006 and 2009. Sincethat time, Groundhog Synergy has been used, with its enhanced capability for detection ofalpha-rich objects. This has increased the number of alpha-rich finds, although the majorityof objects are of lower activity than previously seen (Synergy has greater sensitivity thanEvolution2). Thorough assessment of the effects on the public are the subject of furtherstudy but indicators are that finds are not so significant as to expect change in the overallcriteria for protection of the public that are described in the HPA reports.5.4 Nuvia dosimetry investigationIn the second half of 2010 Nuvia dosimetry bioassay (i.e. urine and faecal) samples from twoworkers engaged in beach monitoring exceeded the urine trigger level (0.2 mBq/day).Nuvia’s internal investigation concluded that a possible explanation for the results could bethe chronic ingestion of beach sand (with the most significant component being fromenvironmental levels rather than associated with find recovery), combined with thecontamination of urine samples with sand from the worker’s hands during sample provision(Randles, 2010).Sellafield Ltd asked the HPA to carry out an independent investigation to gain reassurancethat there was not a risk to the Nuvia workers. The report (Etherington , 2011) found thatthe possibility could not be ruled out that intakes giving rise to committed effective doses inexcess of 1 mSv could have occurred. However, they also found that the possibility could notbe ruled out that the bioassay results, in full or in part, could be explained by samplecontamination.© Nuclear Decommissioning Authority 2011. 82