Waste Disposal Borehole Procedures and Requirements

1. Procedures and Requirements for the Emplacement of Waste In the Disposal Borehole Presenter Name School of Drafting Regulations for Borehole Disposal of DSRS 2016 Vienna, Austria

2. Introduction • Poorly controlled DSRS have caused serious, even fatal radiation accidents. • The IAEA has, almost since its inception, been involved in improving their control. • One potential long-term solution is the Borehole Disposal Concept. • The ease of borehole construction and site characterization make this method of disposal particularly suitable for States with limited DSRS volumes. 2

3. Introduction (cont.) • The BDC system is designed to use commonly available materials and expertise and will help to identifying a experts. • Similarly, borehole drilling/completion will follow proven procedures to those used for deep water abstraction. • Because there is a high level of reliance on the integrity of the stainless steel capsule and container, their manufacture will need to be subject to a strict QC & QM regime. • This and the economies of scale may make it desirable for the container and, to a lesser extent, the capsule to be manufactured by a single supplier.

4. Scope • The borehole disposal concept entails the emplacement of disused sealed radioactive sources and small volumes of low and intermediate level wastes in an engineered facility bored or drilled and operated directly from the surface. • Borehole disposal is viewed mainly as a small scale activity that can be carried out without a large programme of scientific and site investigation.

5. Identification of Necessary Resources • Suitably qualified, experienced, and equipped radiation workers. • Earth moving equipment (and staff) to level the site (if necessary). • Fencing and fencing contractor for security fencing at the site. • Contractors and equipment to drill, characterize, and grout the borehole. • Materials needed for borehole construction (drilling fluid, sand, cement, and borehole casing. • Transport for moving personnel, DSRS, equipment, and materials. • Trained staff to operate the conditioning unit and BDC portable hot cell. • Suitable containers for DSRS transport. • Other consumables (portable power and water of suitable quality). • Accommodation for the disposal team.

6. Preoperational Phase • Identification of materials sources. • Preparation of the site. • Constructing the facility. • Mobilization. • Site security.

7. Main Construction Activities • Mobilization of suitable drilling rig, conditioning, and containerization unit to the site. • Installation of a site security system. • Drilling of the borehole. • Insertion of the casing. • Grouting of the casing. • Plugging of the bottom of the casing. • Commissioning tests to verify that the borehole is constructed in accordance with the approved design.

8. Drilling of the Borehole The most common method employed for the drilling of larger diameter (more than 100 mm) boreholes is rotary air percussion using a down-hole hammer. This type of drilling is ideally suited to hard rock formations and for the likely depths (30 m to 100 m) for the borehole disposal.

9. Borehole Casing The purpose of the casing is to aid operation by stabilizing the rock wall, avoiding snagging of disposal packages, and keeping the borehole dry. The disposal boreholes may be situated in saturated or unsaturated conditions. If a borehole is very stable and dry, the casing may not be needed.

10. Placement of the Casing Bottom Plugand Grouting of the Casing • Using centralizers to position the casing vertically, a free flowing grout is prepared. Using a tremie pipe, sufficient grout is then placed into the bottom of the borehole to produce a bottom seal that is at least 0.5 m thick. • Grouting of the annulus between the borehole sidewall and the outside of the casing ensures that there are no cavities that could provide easy access of groundwater to the casing and the disposal packages.

11. Grouting of the Casing A common procedure is to use a small diameter pipe (tremie pipe) running to the bottom of the bottom of the borehole. Grout is pumped through the tremie pipe so that it fills up the annulus from the bottom.

12. Borehole Commissioning • The straightness of a borehole is measured by the degree to which it deviates along its length from an imaginary centreline running through the borehole. • This is physically determined by passing a dummy through the borehole down to the bottom. • The dummy consists of a rigid hollow steel pipe that has slightly larger dimensions (diameter and length) than the disposal package to be disposed of.

13. Guidelines for an Area where Capsules and Containers are Manipulated • Capsules should be checked for contamination immediately after removal from their temporary shields. • The receiving area and the first transfer zone should be covered with double sheets of polyethylene to prevent equipment contamination. • Ventilation should be maintained in the receiving area/transfer zone. • The operational area should be made as small as practicable. • Operations should be optimized to limit the number of manipulations. • Establish radiation levels before and after each containerization.

14. DSRS Conditioning andContainer Unit The conditioning operation should consist of the following five zones: • Receiving zone. • Transfer zone. • Welding zone. • Leak testing zone. • Container filling/storage zone. .

15. What Containerization Involves Containerization is the placing of a stainless steel capsule (containing one or more DSRS) into a stainless steel disposal container which is cylindrical and made from type 316 L stainless steel. The purpose of containerization is to convert the conditioned DSRS into a disposal package.

16. Transfer to Borehole • The conditioning unit has an overhead crane that extends from the working area to the adjacent borehole. In container filling/storage zone, the disposal container can be placed on the crane and then run out of the conditioning unit so that it hangs directly over the borehole from where it can be emplaced. • This will allow a containerized DSRS to be lifted quickly from its temporary shield and then, with the operators standing at a distance, moved directly to the borehole and lowered into it.

17. Transfer Flask BDC transport/transfer flask

18. Emplacement Before the start of any emplacement action, it is necessary to prepare the borehole by verifying that: • The borehole is empty and dry. • A dummy disposal package can be lowered to the bottom of the borehole. • The borehole has the correct depth and diameter.

19. Borehole Closure, Decommissioning, And Rehabilitation • Removal of casing. • Installing the anti-intrusion plate. • Borehole sealing. • Rehabilitation. • Records retentions.

20. Summary • Borehole disposal concept • Identification of necessary resources • Identification of materials sources • Preparation of the site • Constructing the facility • Drilling of the borehole • Insertion of borehole casing • Placing of the casing bottom plug • Grouting of the casing

21. Summary (cont.) • Borehole commissioning. • DSRS containerization. • Secondary wastes. • Transfer to borehole. • Emplacement. • Closure. • Decommissioning. • Rehabilitation. • Records.

22. Thank you!