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 (gt100 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?