Overview of Borehole Disposal Concept via BDC in Vienna

1. Overview of documents related to the disposal of DSRS via the BDC Presenter Name School of Drafting Regulations for Borehole Disposal of DSRS 2016 Vienna, Austria

2. Content • Why the IAEA borehole disposal concept (BDC) was developed. • The benefits and sustainability of the solution will be elaborated for your understanding. • Where to look for information on the BDC.

3. Why the Borehole Disposal Concept (BDC) • Current concept (BDC) conceived at a meeting of the 1AFRA Waste Management Project Coordinators in 1995 in South Africa. • Difficult to provide the required level of control for DSRS in their countries. • The IAEA provides the secretariat for the AFRA projects and they were approached to fund the development of the concept. 1AFRA – African Regional Cooperative Agreement for Research, Development and Training related to Nuclear Science and Technology.

4. Long term storage NOT sustainable • Developing countries have more important priorities than looking after disused sealed radioactive sources. • Political turmoil and economic hardship in many parts of the world exasperate lack of control. • Lack of knowledge and skills among operators and regulators. • Knowledge management often not carried out. • Conditioning for the long term not affordable and not often done. (e.g. stainless steel drums). • Long term storage without long term thinking leads to corrosion, contamination, accidents and more!!!

5. Development of the Borehole Disposal Concept – Necsa Involvement • 1995 – AFRA Project Coordinators meeting • 1996 – 1Necsa proposal to the IAEA • 1998 – Phase 1 complete – description • 2000 – Phase 2 complete – 1st safety assessment • 2004 – Phase 3 complete – detailed evaluation • 2005 – International Peer Review 1South African Nuclear Energy Corporation Ltd (Necsa)

6. IAEA contribution • Funded all the Necsa work from 1TCF • Studied the concept through the 2ISAM 3CRP • Developed a Safety view through a TECDOC 1368 and Safety Guide SSG-1 • Funded a generic post closure safety assessment – completed 2003 • Currently publishing a report on the generic safety assessment. • Produced technical manual TECDOC 1644. 1Technical Cooperation Fund (TCF). 2Improvement of Safety Assessment Methodologies for Near Surface Disposal Facilities (ISAM). 3Coordinated Research Project (CRP)

7. Requirements Safety Standard • There are 26 detailed requirements for disposal in Document SSR-5 including requirements for :- • Responsibilities of government, the Regulator and Operator. • Passive means for the safety. • Understanding of the disposal facility and confidence in safety. • Multiple safety functions. • Containment of radioactive waste. • Isolation of radioactive waste. • Surveillance and control of passive safety features. • Etc. • Detailed review of these requirements will be addressed in another lecture

8. Safety Requirements apply to all types ofdisposal and disposal facilities • Specific landfill disposal • Near surface disposal • Disposal of intermediate level waste • Geological disposal • Borehole disposal • Safety Guides provide comprehensive guidance on and international bestpractices for meeting the requirements in respect of different types of disposal facility.

9. Key Published IAEA Documents Many unpublished reports including Necsa documents

10. Some of the Necsa reports The complete list of Necsa reports can be found in IAEA-TECDOC-1644

11. Some of the Necsa reports I • GEA-1620 development philosophy • The document provides a useful summary of all the BDF project documents. The key components of the philosophy are: • The approach will be ‘pragmatic’; • The relevant safety requirements will be met; • Operational safety will be ALARA. • GEA-1621 requirements for the borehole disposal facility • This is an overview of the BDF as a long term management solution for disused SRS. The text discusses, evaluates and documents a wide range of policy, regulatory, engineering, logistical and scientific issues related to setting defensible and achievable requirements for safe implementation of the BDF.

12. Some of the Necsa reports II • GEA-1622 borehole disposal facility: generic site selection and characterization • This document provides guidelines for site selection and site characterization for a borehole disposal facility so that, in conjunction with the engineered barriers, the facility will provide radiological protection that complies with international standards. • GEA-1623 design for the borehole disposal facility • This document provides a clear description of the generic or reference design and how the facility would be operated. It provides detailed information on most aspects of the design and operation.

13. Some of the Necsa reports III • GEA-1626 road map and procedures to implement the BDF • This document contains an implementation process (road map) for the BDF and procedures for many of the associated activities such as site selection and characterization, borehole construction, container manufacture, and source conditioning and containerization. • GEA-1627 practical demonstration and qualification • This document provides a description of the various trials and demonstration tests that were carried out. It contains useful information and photographs that help to explain some of the procedures and the choice of materials.

14. Some of the Necsa reports IV • GEA-1628 techno-economic study • This document, referred to in the overview but not technical manual, derives an estimate of the likely cost of the BDF. • GEA-1633 prospective hazard assessment of a borehole disposal facility • This document describes operational activities so as to demonstrate that the doses to operators of the facility can be controlled to within acceptable limits. The estimates for some activities are compared with actual dose measurements that were taken during previous missions where radium sources were pre-conditioned.

15. Some of the Necsa reports V • GEA-1632 generic HAZOP for borehole disposal of spent radioactive sources • This document is likely to be useful to the RPO. It presents an analysis of potential hazards associated with the BDF. Various types of deviation (e.g. ventilation failures, monitoring instrument failures, welding failures, power supply failures, etc.) are listed along with their important characteristics i.e.: • Causes; • Consequences; • Ranking of consequences; • Protecting or mitigating features; • Actions (including recovery to a normal situation).

16. Some of the Necsa reports VI • GEA-1641 practical demonstration of the borehole disposal facility • This report briefly describes Necsa’s intentions with respect to demonstrating the BDF. It is largely of historical interest and is not referred to in this technical manual. • GEA-1643 generic waste acceptance criteria for the borehole disposal facility • This document presents generic waste acceptance criteria (WAC) for the BDF, which may be used to help define site specific WAC. It provides guidelines with regard to the acceptability of materials other than those used in the generic design and associated safety assessment. The document specifically excludes SHARS and neutron sources however.

17. Some of the Necsa reports VII • GEA-1714 waste acceptance criteria for the borehole disposal facility • This document presents generic (but detailed) waste acceptance criteria for the borehole disposal facility. It includes tables of limiting activity levels for individual waste packages based on their heat output and doses arising from operation of the conditioning unit and portable hot cell.

18. Some of the Necsa reports VIII BDF-006-NTW NNR review of borehole disposal investigation This document presents a review of the BDF by the South African nuclear regulator (NNR). The review aims to compare Necsa’s proposals for the BDF with international best practice. The document concludes that “The studies conducted by Necsa, including the generic safety assessment, demonstrated compliance with regulatory requirements, based on international standards”. The document is likely to be helpful to other regulatory bodies. BDF-007-NTW guidance document on the borehole disposal facility (previously published as lg-1043, licensing guide: borehole disposal facility safety case) This presents comprehensive regulatory body guidance to the implementer of a borehole disposal with respect to compliance with regulatory criteria and, specifically, with respect to the preparation of the safety case. The document is likely to be helpful to other regulatory bodies.

19. Some of the Necsa reports IX • QRS-1128A-6 v2 generic post-closure safety assessment (GSA) • This document is a comprehensive generic post-closure safety assessment for the BDF Calculations are performed for three lithological environments (arenaceous, argillaceous and crystalline) that, along with other variables, serve as a proxy for a range of hydrogeological and geochemical conditions. The container corrosion rates are based on localized corrosion of stainless steel. • QRS-1128C-1 v2 (F-GSA) • This document presents further calculations on post-closure safety and should be read in conjunction with the GSA. The effect of a wider range of corrosion rates is explored but the lowest rates used are still significantly higher than those applicable to uniform corrosion.

20. Implementation of the borehole disposal technology Documentation on borehole disposal technology • IAEA documentation package • for governmental authorities and decision-makers Flyer (published) • for regulators, developers, operators, etc.  Technical Manual (in draft)  Safety Assessment Template (TBD)

21. Implementation of the borehole disposal technology Safety documentation on borehole disposal technology • IAEA Safety Standards Series • SSR-5 Disposal of Radioactive Waste. Safety Requirements • SSG-1 Safety Guide on disposal of radioactive waste in borehole facilities • IAEA TECDOC series • TECDOC-1355 Security of Radioactive Sources (2003) • TECDOC-1368 Safety considerations in the disposal of DSRS in borehole facilities (2003)

22. Implementation of the borehole disposal technology Technical documentation on management of DSRS • IAEA TECDOC series • TECDOC-804 Methods to identify and locate DSRS (1995) • TECDOC-776 Reference design for a centralized waste processing and storage facility (1994) • TECDOC-886 Conditioning and interim storage of spent radium sources (1996) • TECDOC-1145 Handling, conditioning and storage of DSRS (2000)

23. Implementation of the borehole disposal technology Technical documentation on management of DSRS • IAEA TECDOC series • TECDOC-1205 Management for the prevention of accidents from DSRS (2001) • TECDOC-1301 Management of spent high activity sources (2002) • TECDOC-1357 Management of long-lived DSRS (2003) • TECDOC 1368 Safety considerations in the disposal of disused sealed radioactive sources in borehole facilities (2003) • TECDOC 1644 Borehole Disposal (2011)

24. Implementation of the borehole disposal technology Technical documentation on management of disused sealed radioactive sources (cont’d) • IAEA TECDOC series • TECDOC-804 Categorization of Radioactive Sources (2003) • IAEA Technical Report Series • Under preparation - Handling, conditioning and storing DSRS (will supersede TECDOCs-886, 1145, 1301 & 1357) • TRS-376 Quality Assurance for radioactive waste packages (1995) • TRS 436 Disposal Options for Disused Radioactive Sources (2005) • IAEA Working Material • Practice oriented training on quality management of RW (2002)

25. How much would borehole disposal cost? • Necsa study for Category 3 to 5 sources estimated 2004 costs at US$407 500 in South Africa. • Recent estimates push this up to ≈US$700 000. • If one includes the deployment of the Mobile Hot Cell another ≈US$350 000 should be added. NOTE: Costs are dependant on inventory and conditions in a country

26. The Concept

27. Objective of IAEA/Necsa Disposal Concept • The technology to be used in the borehole concept is such that each country possessing DSRS will be able to safely implement the concept for its own wastes. • The concept will meet all safety standards as laid down in the IAEA documents. • The concept must be economically feasible to implement, taking into consideration the financial situation in some of these African countries. • The concept should preferably be applicable for both short- and longer-lived radionuclides, such as 226Ra and 241Am.

28. A Simple Water Drill

29. The Concept - Filling the Borehole

30. A single disposal container (van Blerk, 2011) DSRS inside the small capsule which is in turn inside the containment barrier of cement. The disposal container is made of 316L stainless steel. The area surrounding the container is filled up with backfill material which is inside the casing. Grout is pumped into the outside space between the casing and the rock.

31. Concept Detail (van Blerk, 2000)

32. The Disposal Package + Capsules Container Lid Container Backfill Capsules

33. Capsule sizes Two capsule sizes are proposed in the original concept. They are the same sizes as those used in radium conditioning operations. This will be altered for the high activity sources.

34. Dimensions of the capsule, containment barrier and container S=small capsule, L=large capsule Ref: van Blerk 2011

35. Typical dimensions of the borehole • The borehole has a nominal depth of 100 metres that will vary depending on the site conditions. • The disposal zone should be below 30 metres which is the level accepted for maximum intrusion depth. • The outside diameter of the borehole is 260mm. • The outside diameter of the casing is 160mm (≈6 inches). • The inside diameter of the casing is 145.34 mm giving a wall thickness of 7.33 mm. Note: The recommended casing is high-density polyethylene (HDPE)

36. Emplacement Lifting Equipment “Grabber” Grout outside container

37. Down the hole Equipment Cement is placed around the container inside the hole by means of a hopper that delivers the correct amount of cement to cover the disposal container. The lowering equipment “Grabber” has a positive clamping mechanism, which will clamp on to the lifting ring and will only release as soon as pressure is applied to the lifting equipment. Grabber Hopper

38. Options for conditioning • High Activity Sources • Option 1 to condition in a Mobile Hot Cell over the borehole. • Option 2 to condition before the borehole is available in a Hot Cell and then dispose of containers using the Mobile Hot Cell • Lower Activity Sources • Option 1 to condition in facility next to the borehole and dispose directly out of this facility. • Option 2 to condition before borehole is available and then dispose of containers using the Transfer Cask.

39. Transfer Flask In the event that the sources are conditioned away from the borehole, a transfer flask can be used for transporting waste packages to the disposal facility. The transfer flask is fitted with a gate at the bottom, which can be opened during the disposal process. There will be a minimum lead thickness of 100 mm to provide shielding during the transferring process. Used for lower category sources (Cat 3 to 5).

40. Conditioning at the borehole (Cat 3-5) Ref: van Blerk , 2011

41. Conditioning for disposal • The successful radium operations used as a model for conditioning for disposal of lower activity sources. • Difference being the welding of the disposal container which will need different welding equipment. • Can be done in mobile facility such as an ISO transport container. • Procedures need to be developed.

42. Conditioning high activity sources • High specific activity means large shielding requirements such as found in a Hot Cell. • Remote handling necessary including remote welding equipment. • Hot Cell must be big enough to fit large self shielded irradiators and teletherapy heads. • Disposing at borehole site implies large shielding requirement such as found in the Mobile Hot Cell.

43. Typical operation for radium

44. Radium Conditioning Continued

45. Conditioning facility and completed hole

46. Conceptual High Activity Disposal Mobile Hot Cell Borehole

47. Safety Assessment

48. Long Term Safety “With a suitable combination of inventory, near-field design and geological environment, the borehole disposal concept is capable of providing a safe solution for the disposal of both long-lived and short-lived radionuclides”. Quote from International Peer Review 2005

49. International Peer Review (2005) • Safe, economic, practical and permanent means of disposing DSRS. • Applicable to a wide range of DSRS. • Appropriate steel and backfill selected. • High activity sources still to be included. • No full scale demonstration done. • All procedures addressed in Necsa documents.

50. How much would borehole disposal cost? • Necsa study for Category 3 to 5 sources estimated 2004 costs at US$407 500 in South Africa. • Recent estimates push this up to ≈US$700 000. • If one includes the deployment of the Mobile Hot Cell another ≈US$350 000 should be added. NOTE: Costs are dependant on inventory and conditions in a country