Annual Report for 2010/11 and Forward Programme - Sellafield Ltd
Annual Report for 2010/11 and Forward Programme - Sellafield Ltd
Annual Report for 2010/11 and Forward Programme - Sellafield Ltd
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List of FiguresFigure 2.1: Histogram of 137 Cs activity per unit area distribution <strong>for</strong> the coastline between StBees <strong>and</strong> the Duddon Estuary from the March 2000 survey, excluding salt marshes <strong>and</strong> directradiation from the <strong>Sellafield</strong> <strong>and</strong> Drigg sites. ............................................................................ 2Figure 2.2: Stripped 137 Cs count rate determined from June <strong>2010</strong> backpack survey. Theenhanced feature to the south east of the area is an area of vegetated beach. ........................... 4Figure 2.3: Ratio of counts in the 137 Cs window (IW) to counts above this window (AW), <strong>for</strong>data collected by Nuvia <strong>Ltd</strong> from the beach at St Bees between May 2007 <strong>and</strong> October 2008..................................................................................................................................................... 5Figure 2.4: Depth distribution of recovered particles from the beaches in the <strong>Sellafield</strong> area. . 6Figure 3.1: Significance of count rates from superficial 137 Cs sources at 75m. ........................ 8Figure 3.2: Significance of count rates from buried 137 Cs sources at 75m. ............................... 9Figure 3.3: Significance of count rates from superficial 137 Cs sources at 15m. ...................... 10Figure 3.4: Significance of count rates from buried 137 Cs sources at 15m. ............................. <strong>11</strong>Figure 3.5: Significance of count rates from superficial 241 Am sources at 15m...................... 12Figure 3.6: Profile plots showing the significance of measurements on a transect directly oversuperficial 137 Cs sources of 1MBq (black), 10MBq (blue) <strong>and</strong> 50MBq (red) under rapidsurvey conditions, <strong>for</strong> the medium natural background scenario with increasing uni<strong>for</strong>m 137 Csbackground concentrations. ..................................................................................................... 14Figure 3.7: Profile plots showing the significance of measurements <strong>for</strong> a transect 50m fromsuperficial 137 Cs sources of 1MBq (black), 10MBq (blue) <strong>and</strong> 50MBq (red) under rapidsurvey conditions, <strong>for</strong> the medium natural background scenario with increasing uni<strong>for</strong>m 137 Csbackground concentrations. ..................................................................................................... 15Figure 3.8: Profile plots showing the significance of measurements on a transect directly overburied 137 Cs sources of 10MBq (black), 50MBq (blue) <strong>and</strong> 100MBq (red) under rapid surveyconditions, <strong>for</strong> the medium natural background scenario with increasing uni<strong>for</strong>m 137 Csbackground concentrations. ..................................................................................................... 16Figure 3.9: Profile plots showing the significance of measurements <strong>for</strong> a transect 50m fromburied 137 Cs sources of 10MBq (black), 50MBq (blue) <strong>and</strong> 100MBq (red) under rapid surveyconditions, <strong>for</strong> the medium natural background scenario with increasing uni<strong>for</strong>m 137 Csbackground concentrations. ..................................................................................................... 17Figure 3.10: Profile plots showing the significance of measurements <strong>for</strong> a transect directlyover superficial 137 Cs sources of 0.1MBq (black), 0.5MBq (blue) <strong>and</strong> 1.0MBq (red) underdetailed survey conditions, <strong>for</strong> the medium natural background scenario with increasinguni<strong>for</strong>m 137 Cs background concentrations. .............................................................................. 19Figure 3.<strong>11</strong>: Profile plots showing the significance of measurements <strong>for</strong> a transect directlyover buried 137 Cs sources of 0.5MBq (black), 1.0MBq (blue) <strong>and</strong> 2.0MBq (red) underdetailed survey conditions, <strong>for</strong> the medium natural background scenario with increasinguni<strong>for</strong>m 137 Cs background concentrations. .............................................................................. 20Figure 3.12: Profile plots showing the significance of measurements <strong>for</strong> a transect directlyover superficial 241 Am sources of 1.0MBq (black), 5.0MBq (blue) <strong>and</strong> 10.0MBq (red) underdetailed survey conditions, <strong>for</strong> the medium natural background scenario with increasinguni<strong>for</strong>m 137 Cs background concentrations. .............................................................................. 21Figure 3.13: Transects across a 10x10m patch of 137 Cs activity at 50 Bq kg -1 (black), asuperficial 2 MBq 137 Cs source (red) <strong>and</strong> a buried 7 MBq 137 Cs source (blue) at 75m (top) <strong>and</strong>15m (bottom) ground clearance. .............................................................................................. 23Figure 3.14: 137 Cs count rates <strong>for</strong> a transect across a chess-board pattern of 50 Bq kg -<strong>11</strong>0x10m patches at 75m (top) <strong>and</strong> 15m (bottom) ground clearances. ...................................... 24iv
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