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

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

2. Outline of Presentation • Presentation Resources • Regulatory Framework • Definitions • Borehole Sealing • What is sealing? • How is it done? • Institutional Controls (IC’s): active & passive • Post-closure Monitoring • Why monitor? What to monitor for? Where? • Generic requirements for post-closure monitoring, • Summary 2

3. Presentation Resources • International Atomic Energy Agency, BOSS: Borehole Disposal of Disused Sealed Sources – A Technical Manual, IAEA-TECDOC-1644, IAEA Vienna (2011) • International Atomic Energy Agency, Borehole Disposa Facilities for Radioactive Waste, Specific Safety Guide No. SSG-1, IAEA Vienna (2009). • International Atomic Energy Agency, Disposal of Radioactive Waste, Safety Standard Series No. SSR-5, IAEA Vienna (2011). 3

4. Regulatory Framework • Basis in national statues • May be based upon IAEA documents • Many countries have national regulations for LLW disposal • Protection of the public and the environment • Examples of typical regulations governing licensing: • Public dose • Worker dose – conditioning/hot cell • Training • Isotope limits due to site safety assessment • Regulatory Body should provide guidance to the licensee on site closure plans and related issues. 4

5. Processing Definitions Sealing – the removal of the upper 30 m of casing, covering the disposal zone casing with concrete, placement of an anti-intrusion plate, the addition of more concrete and bringing the hole up to grade with several meters of top soils. Monitoring – obtaining and analyzing samples for radionuclides that may impact human health and/or damage the environment and other physical facility aspects (e.g., fence) needed during the active institutional control period. 5

6. Scheme of a Borehole Disposal Facility 6

7. Borehole Closure • Closure takes place after the placement of the last disposal package. • Section of casing above the disposal zone, or at least the top 30 m, is to be removed. • HDPE (plastic) casing may be unscrewed • Steel casing may require down hole cutting. • Casing removal force depends on site geology • Movement of loose material into annulus around casing. • Actions taken during drilling to prevent material from lodging into annulus. • If suspect the force will be great, use steel casing. 7

8. Borehole Closure • With upper casing removed, grout is placed in the borehole to cover the remaining casing. • Steel anti-intrusion plate is fitted. • Above the casing so any drill bit hitting the plate is re-directed into the surrounding rock. • Plate is rectangular with width D and breadth of 0.71D • Plate is placed at about 45° inside the borehole. • Plate with a thickness of 10 mm is likely to be sufficient. • Subsequently the plate is surrounded by backfill grout. • Afterwards, the top section is further backfilled with grout. Last couple meters is filled with soil. 8

9. Institutional Controls • Main aim of geological disposal of radioactive waste is the system is passively safe – no need of human intervention to maintain safety. • So why institutional controls? • Regulatory Body requires it. 9

10. Institutional Controls • Two varieties: Active or passive • Active (for a given period of time; e.g., 100 years) • Monitoring for radionuclides in the environment, • Vital that a baseline was gathered before site was operational for comparison, • Fence maintenance & cover repair. • Passive controls • Deed restrictions, • Warning markers, • Lodging site information in a local, national, and international archive, and • Using soil at top is for security; hide exact location of hole. 10

11. Surveillance and Monitoring • Post-closure monitoring is necessary to ensure integrity of disposal. Plausible pathways are: • Leaching from packages and transport to groundwater. • Airborne release of gaseous radionuclides such as radon. • Main objectives of post-closure surveillance and monitoring: • Show compliance with reference levels established by RB for public health and environmental protection, • To confirm, as far as possible, relevant assumptions made in the safety assessment, • To provide indications of any malfunctioning of the containment leading to unpredicted releases of radionuclides, and • To provide reassurance to concerned persons living in the vicinity of the waste disposal facility. 11

12. Surveillance and Monitoring • Critical part of the safety case: data and verification of modeling • Start before site is operational and continue through active institutional control period. • Build a reliable and comprehensive database available to the public. • Environmental monitoring program is authorized by Regulatory Body via license.

13. Surveillance and Monitoring • Media to sample and locations: • Air (upwind and downwind) • Soil and vegetation (deep rooted is possible), • Surface water (if available), and • Groundwater: background and down gradient. • Frequency: same as during operations. • Extended IC period – frequency based upon results. Regulatory Body can agree to reductions. • Termination: end of active institutional control period.

14. Surveillance and Monitoring • Radionuclides to monitor: • Need estimate of travel time to groundwater and groundwater flow rate (e.g., flowing or stagnant), • Mobile isotopes in the inventory, such as: • Pu-238/9 (if mobile) and Am-241 • Cs-137 • Sr-90 • Co-60 • Ra-226 and Rn • At Washington’s disposal site, sampling is performed quarterly (for nearly 30 years)

15. Summary • At closure the borehole disposal facility needs to seal any open boreholes. • Sealing is accomplished by removing the upper portion (30 m) of casing, adding concrete over the remaining casing, the placement of an anti-intrusion plate, more concrete and soil at the top of the hole. • Institutional controls are put in place for a given amount of time. • Operational phase monitoring and surveillance continues into the active institutional control period. • Monitoring stops when passive IC starts. 15

16. Thank you!