Presenter Name School of Drafting Regulations for Borehole Disposal of DSRS 2016 Vienna, Austria

1. Containment and Containerization Presenter Name School of Drafting Regulations for Borehole Disposal of DSRS 2016 Vienna, Austria

2. Introduction • High activity and long-lived radioactive waste requires containment and containerization. • A site should be identified that provides favourable conditions for containment and isolation of the waste from the biosphere and for preservation of the engineered barriers. • The purpose of encapsulation is to contain the radionuclides in the waste through a combination of physical and chemical functions that are effective for hundreds or even thousands of years. 2

3. Scope of Lecture • This lecture is focused on containment and containerization methods to ensure effective isolation for hundreds or even thousands of years. A well-designed and well-located borehole disposal facility should provide reasonable assurance that radiological impacts in the post-closure period will be low both in absolute terms and in comparison with any other waste management options that are currently available at a reasonable cost.

4. Containment To provide confidence in long-term safety, a waste disposal system should employ a number of complementary engineered and natural barriers that will be effective over different timescales and will provide a number of safety functions. They may include, for instance: • A waste container made of a corrosion-resistant material that gives a container lifetime of about a thousand years. • A cement based backfill placed between the container and the borehole casing to create high pH conditions that limit solubility and promote sorption and so provide chemical containment for thousands of years. • A location where the rate of groundwater movement and the degree of radionuclide sorption onto the surrounding rocks together ensure that the radionuclides would take many thousands of years to migrate to the biosphere.

5. Containment (cont.) The engineered barriers may include: • The original casing (for disused sealed sources). • Welded metal (e.g., plain carbon or stainless steel) capsules for some small volume waste (e.g,. radium sources). • A metal (e.g., plain carbon or stainless steel) waste container. • An encapsulation matrix (e.g., cement grout, bentonite, or lead) within which radioactive waste (e.g., radium sources) may be embedded, creating the waste form within the container. • Borehole backfill (e.g., cement grout) surrounding the waste packages. • Metal or plastic borehole casing to support borehole walls during drilling or emplacement operations. • Casing seal to fill any voids between the casing and the borehole. • Borehole clay seal or cement plug several metreslong, placed in the borehole above the disposal.

6. Containment (cont.) The various components of the engineered and natural systems also need to be complementary. Examples of non-complementary components are: • The use of ordinary Portland cement when the surrounding groundwater or geology has high levels of sulphate (common in some types of clay); • The use of swelling clays in highly saline environments or in groundwater with high levels of potassium.

7. What Conditioning Is: In the BDC system, conditioning is the placing of one or more DSRS within a stainless steel capsule that is subsequently seal welded. Conditioning unit in Pelindaba, South Africa

8. Conditioning (cont.) Conditioning provides: • Conversion of the DSRS to a special form radioactive material; • Proper documentation for the DSRS; • Physical protection from damage and radionuclide release; • A standard sized package that is more easily handled.

9. General Requirements for Conditioning • Continuous control of contamination must be carried out. • The transfer zones should be covered with double sheets of polyethylene wherever contamination may be expected to take place. • The operational area should be made as small as practical. • Suitable ventilation should be maintained, extracting to the outside air via HEPA filters. • The operation should be optimized to limit the number of manipulations of the sources. • Special attention must be given to the receiving area where the incoming transport packages are handled.

10. Operations in the Conditioning Unit The conditioning operation should consist of the following five zones: • Receiving zone. • Transfer zone. • Welding zone. • Leak testing zone. • Container filling/storage zone. Conditioning and containerization facility situated adjacent to the BDC Facility

11. The Following Records Should be Maintained • Details of the make-up of each capsule. • Source identities and radionuclide contents together with confirmatory measurements (e.g., gamma spectroscopy results). • Unique capsule number. • Confirmation that all the steps in the procedures were completed as planned (with dates and signatures). • Description of any non-conformances to the procedures and an explanation of the likely consequences. • Leak test results on the capsules.

12. 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.

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 practical. • Operations should be optimized to limit the number of manipulations. • Establish radiation levels before and after each containerization.

14. Secondary Radioactive Wastes • While it is not expected that secondary wastes will be generated by the conditioning processes, it is possible that this could occur if a leaking DSRS is encountered and it is necessary to do some decontamination. • The basic waste management principles should be adhered to when radioactive contamination is encountered during conditioning: namely, waste prevention and minimization.

15. Summary The IAEA BDC system aims to provide for the long-term management of DSRSs through proper: • Collection, characterization, and conditioning of DSRS in capsules. • Safe interim storage of the DSRS. • Selection, characterization, and recommendation of a suitable disposal site. • Containerization of the capsules into a disposal package. • Permanent disposal of the containerized DSRS, including SHARS, in a specially constructed borehole that is at least 30 m deep.

16. Thank you!