Regulations on Safety Design of Tailings Pool in Uranium Hydrometallurgy Plant
2Expert Interpretation
Professional interpretation of EJ 794-93 uranium hydrometallurgical plant tailings pond safety design standards, covering site selection principles, dam stability calculations, radiation monitoring requirements and decommissioning disposal specifications, and providing technical points for the safety management of tailings ponds throughout their life cycle.
Analysis of the core content of the standard
As a mandatory specification for the construction of tailings facilities in my country's uranium hydrometallurgy plants, this standard has established a full-process safety management and control system covering site selection, design, operation and decommissioning. The technical points are mainly reflected in:
| Technical dimension | Conventional tailings pond | Special requirements for uranium tailings pond |
|---|---|---|
| Design basis | Flood control and earthquake resistance | Three principles of superimposed radiation protection (legitimacy, optimization, dose limit) |
| Dam structure | Initial dam + accumulation dam | Mandatory installation of drainage facilities and radiation monitoring system |
| Decommissioning standards | Physical stability | Additional radioactive constraint of surface radon exhalation rate ≤ 0.74Bq/m²·s |
Key technical requirements
1. Hierarchical design system
The tailings pond is divided into two levels according to the storage capacity and downstream impact:
- Level I: storage capacity > 10 million m³ or threat to important facilities
- Level II: storage capacity ≤ 10 million m³ and less impact
2. Dam stability control
The Swedish arc method is used for static stability calculation, with the following requirements:
- Safety factor for normal conditions ≥ 1.25
- Safety factor for emergency conditions (earthquake/rainstorm) ≥ 1.15
Typical Engineering Cases
A uranium tailings pond adopts a permeable rockfill dam design. By setting up a filter layer and a seepage line monitoring system, it has achieved stable operation for 20 years in an 8-degree earthquake zone.
Radiation protection special
Implement the ALARA principle (as low as reasonably practicable), with specific limits:
- Annual effective dose for staff ≤50mSv
- Annual dose to eye lens ≤150mSv
- Lifetime average annual dose for residents is lower than the management limit
Monitoring system design
It is required to establish a monitoring network covering nuclides such as 222Rn and 226Ra, with sampling frequency:
- Radon gas in the reservoir area: once every half month
- γ radiation in the external environment: once a quarter
Implementation suggestions
- Design phase: give priority to permeable rockfill dams and strictly verify the reliability of the anti-seepage system
- Construction phase: establish real-time monitoring of the infiltration line and control the dam filling rate to ≤3m/year
- Decommissioning phase: adopt a multi-layer covering structure (clay + vegetation) to ensure that the radon exhalation rate meets the standard