Post-closure of disposal facilities

Requirements on surveillance control of disposal facilities after closure have been laid down in China. The Regulations on Radioactive Waste Safety (HAF401) require that, after closure of a disposal site, institutional surveillance and control should be maintained to:

• prevent inadvertent public intrusion onto the site,

• prevent movement and disturbance of disposed radioactive materials,

• monitor the performance of the disposal site against design basis stand­ards, and

• implement necessary remedial actions.

The period following closure of a disposal facility generally includes closed, semi-closed and open phases. Closed phase means a period when the dis­posal facility that has just been closed is kept under closed condition and that no one can access it unless for the purposes of a supervisory task. Semi-closed phase means a period when waste is covered with well — structured cover and associated hazards has proven very small, and people are allowed access but without any activities relevant to drilling and excava­tions. Open phase means a period when radioactivity of waste has reduced to the level at which radiation protection is no longer needed following expiration of the required control period and the site can be fully open to the outside.

Post-closure surveillance of the localities where a disposal facility is located are the duty of the local government. Costs required for carrying out post-closure maintenance, monitoring and emergency measures are estimated before the operation of such a disposal facility and collected in an appropriate amount from the associated waste disposal fees. Re-estimation, and necessary adjustment, can be made for such costs to meet the changing circumstances. Post-closure supervision, such as environmental monitoring, access restriction, installation maintenance, file preservation and possible emergency actions, should be carried out under the auspices of the envi­ronmental protection agencies at both the national and the provincial levels. Both the Guangdong Beilong and the Northwest China LILW disposal sites are in operation, and far from closure.

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