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

SSEM/2011/4730 June 2011Alpha-rich Particle Distance from Sellafield Pipeline5040173 finds216 finds50 finds30Frequency20100-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24Distance in Km (positive is North, negtive is South)Oxide-50 finds Magnox-17 finds Alpha-rich- 514 findsFigure 3.30. Alpha-rich Particle Find Distances from the Sellafield pipeline.Further work is planned to improve understanding the uncertainties associated with theMagnox and Oxide designations for each find based on SL and NPL analysis data. With thisrefined data the apparent Oxide alpha-rich particle find correlation with distance will bereviewed.Another example of how GIS can be employed is the query concerning finds found in theoverlap area between monitoring transects. This analysis can provide information onrepopulation rates and the potential for finds to be located in undisturbed sand strata. Theinterim results of this analysis, for the Sellafield beach area over the 2010/11 financial year,are summarised in Table 3.15 and Table 3.16 below. The monitoring transects are definedas the area monitored within a tide cycle and by default are the daily monitoring areas.Monitoring transects that overlap were identified using GIS extents, which have a 2 metreboundary around monitoring points. The find location within the overlap area was thencompared to the nearest height data points for both monitoring periods. Height data are notnecessarily co-located for each period but were found to be less than 30 cm from the findlocation and often much closer. The transect overlapping with the find transect are definedas; 'before' overlap - for a monitoring period before the period in which the find was found'after' overlap - for a monitoring period after the period in which the find was found'before and after' overlap - for monitoring periods both before and after the period inwhich the find was found.© Nuclear Decommissioning Authority 2011. 57