Appendix CRF - Part 3 - Northamptonshire County Council

the stresses which would be imposed during the types of earthquake
which occur in the UK.
- Transport accident scenarios are not discussed because transport is
outside of the scope of the authorisation and is regulated under an
existing regime of Dangerous Goods Regulations. Transport accidents
on the site are considered as part of the dropped load scenario and a
transport accident involving leachate is specifically considered.
8.06 The full set of results is given in the Annexes and the following conclusions are
reached from the assessment:
8.1 Pre-Closure – expected to occur
Direct Radiation Exposure from Waste Handling and
Emplacement
8.1.1 The dose criteria are the legal limit to workers of 20 mSv/yr, the site criterion of 1
mSv/yr for workers, the dose guidance level of 0.02 mSv/yr for the public and the
dose constraint for the public of 0.3 mSv/yr.
8.1.2 The impacted group is landfill workers and the public near to the site. The
emplaced waste can only affect the landfill workers because there is no line of
sight for direct radiation from landfill void.
8.1.3 The assessment is contained within Annexes D and H.
8.1.4 Waste Emplacement: The scenario is the external radiation exposure of workers
in the vicinity of the waste emplaced in the landfill after it has been covered.
8.1.5 The assessment is contained within Annex H.
8.1.6 Annex H illustrates the dose rate for varying cover thicknesses using two
illustrative cases, one of which is a worst case. The advice of the radiation
protection advisor is that the maximum radiation dose 1 m above the covered
waste should be less than 2 microSv/hr in order to ensure the occupational dose
is considerably less than the dose criterion of 1 mSv/yr.
8.1.7 Annex H demonstrates that for most cases a 300mm thick cover layer will more
than achieve the dose rate. For the worst case of waste containing Co-60 at 200
Bq/g a cover layer of 700mm would be required to achieve the dose rate, but this
is exceptional.
8.1.8 The proposed authorisation condition is that a minimum cover layer of 300mm be
utilised and that if the dose rate 1 m above the waste is still greater than 2
microSv/hr then further cover will be added in order to achieve the dose rate.
The minimum cover layer of 300mm is adequate to ensure daily physical
protection of the waste.
Application for disposal of LLW including HV-VLLW under RSA 1993,
for the East Northants Resource Management Facility:
Supporting Information
July 2009
59
WS010001/ENRMF/CONSAPPCRF 378