Options for Disposal of Active Material

1. Options for Disposal of Active Material Dr. Brian Heaton Aberdeen Radiation Protection Services Ltd.

2. Waste Streams • Exempt waste (Very Low Level Waste) • Medium Activity Waste (Low level Waste) • High Activity Waste (Medium Level Waste)

3. Ground Rules • Dilute and disperse is not an option for radioactive waste. • Shallow Burial is not considered an option for long lived radioactive waste.

4. Exempt Waste • Waste at less than 1 Bq/g isotopic activity. • Care must be taken to ensure no reprocessing takes place that would raise level to above this. • Could the normal operation of a sludge farm be considered to be “deliberately diluting” the waste.

5. Problem Wastes • High Activity wastes which must clearly be subject to controlled disposal. • The large volumes of medium activity silts and sludges from vessels, sand contaminated by leaking produced water and perhaps the residues in some ponds/pits that are not exempt.

6. International Standards 1 • During the operation of a practice (an operation which raises the exposure radiation dose of a worker or a member of the public above background levels) the dose to a member of the public is subject to a constraint of 0.3mSv/y.

7. Methods of Achieving • Shielding • Limitations on Access (Distance) • Time • Ensuring this happens is generally not a problem

8. International Standards 2 • Until the present a potentially uncontrolled disposal had to ensure that the dose to a member of the public did not exceed 10µSv/y. This figure has been used for many years. • There is a move to change this in the future to 0.3 mSv/y.

9. High Level Waste • Really only one option - deep burial through an injection well. • Could be very expensive in terms of cost of injection well and injection facilities if new well required. • In practice there could be a very small amount required to be reinjected per year.

10. Medium Level waste • Could some of this be land farmed? • Risk assessment would have a constraint of 0.3mS/y.

11. Exposure Scenarios • Areas where the land farms are located are remote and when oil production ceases the water supply currently available will generally disappear. • What is the possibility of people going to live in the area of a disposal site for a period of time and if so for how long?

12. Questions arising from this • What exposure scenarios should be used when calculating possible doses? • What constitutes long term and surveillance?

13. Radiation Hazards • In the long term (>100 years) the hazard is really only due to the radium 226 and its progeny. • Main component of dose received is the external dose from the ground.

14. Would these areas be attractive? • Relatively soft flat area for living on. • Potentially grassy in times of rain (but very soft and muddy). • Access tracks/roads perhaps centre of network or suitable transit point.

15. Shallow Burial • Can it be used in areas of concern. • Excavating trenches which are properly capped to a very high standard. • Placing large boulders on top using heavy lifting machinery. • Destroy access roads.

16. National Problem • Should national governments take responsibility or is the operators responsibility?