Appendix CRF - Part 3 - Northamptonshire County Council

Radiological Assessment 0820-2
Version 2
industry decommissioning wastes that might be considered for disposal at the
ENRMF.
The waste stream used to illustrate the potential radiological capacity of the ENRMF
has been compiled from information on material in the Meashill Trenches at Harwell.
This waste stream comprises a mixture of activated synchrotron components, reactor
components and decommissioning/land remediation wastes, but is dominated by Co-
60 through the presence of activated steel. Other waste streams from Harwell are
more typically dominated by Cs-137. To partly reduce this dominance by Co-60, the
2000 inventory provided has been decayed to 2010 (Table 2.6).
The inventory presented in Table 2.6 does not represent the complete inventory for
the Meashill Trenches. There will be small quantities of long-lived daughter
radionuclides from the plutonium, uranium and thorium decay series. These become
of increasing importance as the inventory decays, and are considered in the long-term
assessments, but are not significant after only 10 years of decay. There are likely to
be other radionuclides present, but these would contribute much less to any potential
dose than the radionuclides listed.
Radionuclide Half-life
(years)
2000 inventory 2010 inventory
MBq % MBq %
H3 12.3 5.70E+00 0.02 3.25E+00 0.03
Co60 5.27 3.00E+04 89.90 8.05E+03 72.25
Cs137 30 1.20E+03 3.60 9.52E+02 8.55
Ra226 1600 1.00E+02 0.30 9.96E+01 0.89
Th232 1.4E+10 4.00E+01 0.12 4.00E+01 0.36
U234 2.44E+05 5.00E+02 1.50 5.00E+02 4.49
U235 7.04E+08 2.40E+01 0.07 2.40E+01 0.22
U238 4.47E+09 5.00E+02 1.50 5.00E+02 4.49
Pu238 87.7 4.00E+01 0.12 3.70E+01 0.33
Pu239 2.41E+04 4.00E+02 1.20 4.00E+02 3.59
Pu240 6540 4.00E+02 1.20 4.00E+02 3.59
Pu241 14.4 6.18E+01 0.19 3.82E+01 0.34
Am241 432 1.00E+02 0.30 9.92E+01 0.89
Total 3.34E+04 1.11E+04
Table 2.6 Illustrative inventory for wastes from the Meashill Trenches, Harwell.
The 2000 inventory provided by UKAEA Harwell has been decayed to
2010 to provide an input to radiological capacity calculations.
Galson Sciences Limited 13 14 July 2009
WS010001/ENRMF/CONSAPPCRF 563