tanks, etc., which hold the sludges. Consideration must also be given to the disposal route for the sludge if and when it becomes significantly contaminated. Since significant contamination of the water supply could only occur following a large, beyond design-basis accident at Daya Bay, which is highly unlikely, it is not considered necessary to include detailed plans for the disposal of contaminated sludges in the Contingency Plan.
As well as the water in the reservoir, consideration must be given to the water entering the reservoir from the catchment area. The level of contamination in the incoming water should be monitored and compared with standards set by the World Health Organisation, (ref 32), the DERI. for drinking water, and also the level of contamination in the reservoir. Provided the level of contamination is below the appropriate DERL then it may be regarded as potable and may be allowed to enter the reservoir, however, the ALARP principle should still be applied and even very small doses of radiation to the public should be minimised. The decision tree in Figure 9.2 should ensure that the actions taken with regard to the water entering the reservoir from the catchment areas comply with the ALARP principle.
FIG 9.2
FLOW CHART
FOR DECIDING
IF CATCHMENT
AREA WATER SHOULD BE ALLOWED INTO RESERVOIR
NO
START
Does the level of
NO
YES
contamination exceed World Health Organisation Standards?
NO
Is the level of contamination
above the DERL?
YES
Is level of
contamination
YES
above level
already in
reservoir?
Let Water into
Reservoir
NO
Are Supplies of Water Plentiful?
YES
63
Dump Water