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

SSEM/2011/4730 June 2011normal distribution hypothesis would be rejected. The corresponding particle plot (Figure3.27) gives better hypothesis testing statistics and the log normal distribution of 137 Cs activityin beta-rich particles would be accepted. The plots show a similar under representation athigher activities but differ at the lowest activities with stones being under represented andparticles being over represented. The beta-rich particles show a similar pattern to that foundfor alpha-rich 241 Am activity.Figure 3.26. Probability plot of Log of 137 Cs Stone Activity.Figure 3.27. Probability plot of Log of 137 Cs Particle Activity.As for alpha-rich particles, further work on fitting distributions to beta-rich particle data isplanned using data modified by the detection efficiency, as suggested by the statisticalsupport contract (see section 3.2.2.4).© Nuclear Decommissioning Authority 2011. 51