GB 14586-1993Technical regulations for the environmental management of decommissioning of uranium mining and milling facilities (English PDF)

3.1 Uranium mining and milling facilities

Sites, equipment, structures, buildings and other facilities of a certain scale engaged in the mining, beneficiation and milling of uranium ore, including:

a. experimental facilities and sites obtaining more than 10 kg of uranium per year from natural ore;

b. pits and shafts excavated to evaluate uranium deposits;

c. uranium mines;

d. uranium mills;

e. radioactive waste treatment systems.

3.2 Decommissioning

The after-treatment of uranium mining and milling facilities that have permanently ceased operation, carried out to protect workers and the public from exposure to residual radioactivity and from other possible hazards.

3.3 Waste disposal

The placing of solid waste in tailings impoundments, waste rock dumps, mined-out areas or other designated sites, where it is treated and not retrieved. Disposal also includes the controlled discharge of waste gas and waste water to the environment.

3.4 Stabilization

Planned actions of necessary treatment and disposal of waste rock dumps and tailings impoundments to maintain their long-term stability and to prevent collapse, washout and the resulting environmental pollution caused by natural forces or other causes.

3.5 Safety analysis

The analysis and calculation of the risks associated with an activity that is to be carried out.

3.6 Waste rock

Material hoisted out of the mine pit (shaft), including:

a. gangue essentially free of uranium and thorium;

b. low-grade uranium and thorium material of no recoverable value.

3.7 Tailings (residues)

Here meaning:

a. the rejected fraction produced in the ore-dressing process;

b. the residues discarded after heap leaching of ore;

c. the sands and slimes discarded by a uranium hydrometallurgical plant after uranium has been leached out.

3.8 Tailings impoundment (tailings pond)

A dedicated facility for settling and storing the sands and slimes contained in the tailings slurry of a hydrometallurgical plant.

3.9 Radon exhalation rate

The quantity of radon released into the air through a unit area of an interface per unit time.

5.1

Before a uranium mining and milling facility ceases production, a decommissioning application report shall be submitted to the competent authority. The whole decommissioning process shall generally be completed within three years.

5.2

Content of the decommissioning application report for a facility:

5.2.1

The name, nature, category, scale, service life and reason for decommissioning of the facility, and the date on which operation ceased.

5.2.2

The kinds and quantities of the pollution sources remaining after decontamination of the facility, their total radioactivity, specific activity, and the composition and content of non-radioactive hazardous substances.

5.2.3

A description of the contamination level of the contaminated structures and production sites.

5.2.4

On the basis of the extent to which the facility meets the standards after decontamination and remediation, a statement of whether decommissioning is for unrestricted or restricted use, together with an account of its environmental impact and a safety analysis.

5.3

When submitting the decommissioning application to the competent authority, the operator of the facility shall at the same time submit the decommissioning plan and carry out an optimisation analysis of the proposed plan.

5.4

On receipt of the decommissioning application report, the competent authority shall promptly organise experts to review and approve the decommissioning report and the environmental remediation plan.

5.5

An organisation qualified for environmental assessment shall be commissioned to prepare the environmental impact report which, after preliminary review by the competent authority, shall be submitted to the national environmental protection administrative authority for examination and approval.

6.1 Disposal of contaminated equipment

Contaminated equipment, materials, scrap steel and iron, etc. shall be decontaminated until their non-fixed alpha and beta surface radioactive contamination meets the requirements of the relevant standards.

6.2 Mine shafts

6.2.1

Adits and shaft collars of decommissioned mines, and raises and ventilation shafts leading to the surface, shall be permanently sealed so that the seal is tight, solid, durable and free of leakage. After sealing, the adits and shaft collars shall be covered with a thickened, well-compacted layer of earth and stone to restore the landform and prevent natural collapse and man-made damage.

6.2.2

Areas where subsidence or caving may occur shall be treated: permanent buildings shall be removed, and in areas where caving cannot be allowed, pillars built of waste rock shall be used as support to control surface caving and subsidence.

6.2.3

For mines from which contaminated water may flow out, effective measures shall be taken to prevent pollution of the environment.

6.3 Open-pit mines

6.3.1

The slopes of open pits shall be stabilised to prevent spalling and landslides.

6.3.2

Sections with steep slopes of great height difference shall be enclosed by walls, and permanent no-entry signs shall be erected to prevent accidents to people and animals.

6.3.3

Where the average radon exhalation rate from the surface of an abandoned open pit exceeds the limit specified in clause A2 of Annex A, the pit shall be covered with soil and revegetated to reduce radon exhalation.

6.3.4

Surface structures which, after decontamination measures, still fail to meet the requirements of 10.1.2 shall be properly disposed of as radioactive waste.

6.4 In-situ leaching sites

In the decommissioning of in-situ leach mining, the mine water shall be restored to an acceptable water quality standard, and groundwater and surface water shall be protected from pollution.

6.5 Hydrometallurgical plants

6.5.1

In the decommissioning of a hydrometallurgical plant, contaminated ground, floors and building foundations shall be removed in accordance with 10.1.2 and clause A3 of Annex A; these wastes may be buried in the tailings impoundment.

6.5.2

At decommissioned heap-leach sites, the leached residue heaps shall be placed in the tailings impoundment or covered with suitable material and properly treated.

6.5.3

Sites contaminated by ore heaps shall be cleaned up; where necessary, detectors shall be used to locate deeply buried contaminants, which shall be removed until the residual surface contamination is reduced to an acceptable level.

6.6 Waste rock dumps

6.6.1

Retaining dams shall be built at waste rock dumps to prevent the waste rock from sliding and being washed away.

6.6.2

Flood-diversion ditches shall be provided around waste rock dumps to prevent floodwater from scouring and soaking them.

6.6.3

Where the average radon exhalation rate from the surface of a waste rock dump exceeds the limit specified in clause A2 of Annex A, the dump shall be covered with soil and revegetated.

6.7 Tailings impoundments

6.7.1

The decommissioning disposal of a tailings impoundment shall bring the radon exhalation rate and the gamma radiation level below the specified limits, and shall prevent dam collapse, loss of tailings and pollution of the environment by seepage water.

6.7.2

No depressions shall be left within a tailings impoundment at decommissioning; they may be filled with earth or waste rock. Before covering with soil and revegetation, the top of the impoundment shall first be graded to a slope of 2% to 4%. Where there is no dam, the side slopes shall be trimmed to a gradient of 1:3 to 1:5 and then protected with stone pitching 50 cm to 100 cm thick; stabilisation requirements shall be met and facilities for flood discharge and seepage water recovery shall be retained.

6.7.3

The cover over the tailings shall use materials chosen rationally to suit local conditions; the thickness of the cover layer shall meet the requirements of clause A2 of Annex A and shall prevent wind erosion, rainwater scouring and loss of tailings.

7.1

After completion of the decommissioning works, monitoring shall be carried out in accordance with EJ 432. The purposes of the monitoring are:

a. to assess whether the decommissioning works comply with the requirements for radioactive waste disposal issued by the State and the relevant authorities, and to verify whether the environmental impact report corresponds to the actual situation;

b. to detect promptly any events and pathways that may pollute the environment;

c. to provide data for the acceptance and handover of the facility.

7.2

When the completion report of the decommissioning and remediation works is submitted, an assessment report on the current environmental status of the decommissioned facility shall be submitted at the same time to the competent authorities concerned.

7.3

On receipt of the completion report and the environmental status assessment report, the competent authority shall, together with the local government, organise experts to examine and accept the environmental protection measures and the quality of the works of the decommissioning.

8.1

When a decommissioned facility is handed over to the local authorities, the decommissioning organisation shall hand over the completion report and the environmental status assessment report to the receiving organisation. The receiving organisation shall carry out supervisory monitoring within one year after receipt and, once it has been confirmed that the environmental management standards for decommissioning are met, shall complete the formal transfer procedures; thereafter the receiving organisation shall be responsible for long-term surveillance.

8.2

Decommissioned facilities shall be subject to long-term surveillance and management, the main content of which includes:

a. preventing exposure of waste rock dumps and tailings impoundments;

b. ensuring that the enclosure and isolation system adopted effectively prevents pollution of groundwater and surface water caused by the migration of radionuclides;

c. the exhalation of radon from waste rock and tailings;

d. the effects of radioactive dust and gamma radiation.

8.3

Environmental monitoring and assessment reports after the transfer of a decommissioned facility shall be prepared by the relevant local authorities.

9.1

To ensure that the quality of the decommissioning works achieves long-term stability, a quality assurance programme for the decommissioning works shall be prepared together with the decommissioning plan, and the design and construction organisations shall be required to establish specific quality assurance measures.

9.2

The design of major decommissioning works shall be entrusted to an organisation holding design qualifications; the design shall meet the requirements of the approved environmental impact report, and the construction design shall be examined and approved by the higher competent authority before construction may begin.

9.3

Files shall be established and kept permanently for the decommissioning application report, decommissioning plan, design, construction and acceptance records, environmental monitoring data, environmental impact assessment report and the related quality assurance documents of the facility.

9.4

The design department and the decommissioning organisation shall inspect and supervise the quality of construction, and quality problems found shall be resolved within a set time.

10.1

The radiation dose limits for facility decommissioning shall comply with the requirements of GB 8703 for the public and the environment.

10.1.1

After final disposal of the decommissioned facility, and taking into account the characteristics of the environment and the social and economic conditions, the additional exposure dose to surrounding residents caused by the decommissioned facility shall be limited to an appropriate fraction of the lifetime average annual effective dose equivalent value specified in that standard, leaving an adequate share for other possible exposures.

10.1.2

Contaminated equipment, materials, buildings, etc. whose non-fixed alpha and beta radioactive surface contamination after decontamination is <= 0.08 Bq/cm2 may be used in general industry (except the food industry) after monitoring and permission by the radiation protection authority.

10.1.3

The surface contamination limits for unrestricted use of contaminated scrap steel and iron after cleaning and decontamination are given in clause A1 of Annex A.

10.1.4

The limits for the average surface radon exhalation rate of waste rock dumps, tailings impoundments, heap-leach and in-situ leach sites and abandoned open pits after final disposal are given in clause A2 of Annex A.

10.1.5

The maximum specific activity limits for radium-226 in soil at different depths after decontamination and remediation of land are given in clause A3 of Annex A.

10.1.6

When seepage water from mines, waste rock dumps, tailings impoundments, heap-leach and in-situ leach sites, abandoned open pits and similar facilities after final disposal flows into the environment, the annual dose received by the critical population group from the radioactive substances it contains shall comply with 10.1.1.

10.2

Discharge standards for non-radioactive toxic and hazardous substances shall be applied in accordance with the relevant national regulations.