TOPICAL SESSION MANAGEMENT OF DECOMMISSIONING WASTES

Transcription

1 TOPICAL SESSION MANAGEMENT OF DECOMMISSIONING WASTES Waste Technology Section WATEC 2004, Oct 2004

2 Presentation Objectives Highlight the interactions between decommissioning and waste management (cross-cutting issue in WTS) Highlight the individual steps from generation to disposal of decommissioning wastes Highlight the need for early planning and integrated approach Highlight the importance of waste minimization and segregation in decommissioning Describe two ongoing tasks of the WTS programme in detail

3 Speakers M. Laraia: Introductory Remarks on the Topic and Issues in Upstream Activities V. Efremenkov: Predisposal Aspects of Radioactive Decommissioning Waste R. Dayal: Coordinated Research Project Disposal Aspects of Low and Intermediate Level Decommissioning Waste

4 Introductory Remarks on the Topic and Issues in Upstream Activities Michele Laraia Waste Technology Section WATEC 2004, Oct 2004

5 Fundamentals Radioactive waste is the logical progression and link from predecommissioning radioactive inventory to a post-decommissioning state i.e. characterization > radioactive inventory > decommissioning> waste generation > types > categories > conditioning > transport > storage > disposal

6 Fundamentals (ctd) Decommissioning waste inventories can be much larger than those produced during normal operation > >1000 TBq at shutdown for a commercial reactor. It is estimated that decommissioning waste arisings can be of the order of magnitude of all operational waste.

7 Fundamentals (ctd) The large majority of decommissioning waste will be non-radioactive. Out of the radioactive waste, most will be LILW ( of them the greatest part VLLW as defined in French terminology). HLW will normally be a small part of the entire inventory at least for reactor facilities.

8 Fundamentals (ctd) Waste management costs could be 50% or more of the overall decommissioning costs in some projects.

9 Basic Waste Management Principles for Decommissioning Radioactive waste shall be managed in such a way as to Secure an acceptable level of protection for human health Provide an acceptable level of protection from the environment Not impose an undue burden on future generations Radioactive waste will be managed within an appropriate national legal framework Generation of waste shall be kept to the minimum practicable Interdependencies among all steps in the radioactive waste generation and management shall be appropriately taken into account

10 Sources of Radioactive Wastes in Decommissioning Fission products (from the nuclear fission process, typically t½ ~ 30 years) Actinides ( from nuclear absorption in uranium, typically t½ > 10,000 years) Activation products (from nuclear activation of materials, typically t½ < 30 years) Natural decay affects the radionuclide composition

11 Radioactive Inventory Categories RADIOACTIVELY CONTAMINATED (all plant systems) ACTIVATED ( reactor vessel and internals, biological shield)

12 Categorization of wastes Based on potential hazard and methods for handling and disposal IAEA definitions, Safety Series No G- 1.1, 1994, Classification of Radioactive waste. Clearance levels are formulated under the Waste Safety programme of the IAEA (RS- G.1.7, 2004) New approach based on VLLW ( France, Spain)

13 Radioactive waste de-categorization Natural decay may reduce radioactive concentrations in waste to the point of downgrading their categories e.g. from HLW to LILW, or from LLW to VLLW or exempt waste. Decontamination could affect categorization as well. Given the large amounts of decom waste and the dramatic disposal cost differences between waste categories, de-categorization is financially to the overall decom programme

14 Decommissioning strategies in lack of waste disposal facilities Where no suitable waste disposal facilities for the amounts and categories of decommissioning wastes are available, the following options exist and should be evaluated and documented in the Decommissioning Plan: - to maintain the facility in safe enclosure (not a final solution); - to dismantle the facility and store generated wastes in temporary waste storage facilities; - in special cases, in-situ disposal (entombment) of the entire facility or parts thereof may be considered.

15 A New Trend in Decommissioning Strategies Based on conclusions of a few recent international events (Berlin conf 2002, Rome Seminar 2004) there is growing consensus that immediate dismantling is the preferred option. On one side, this is a factor fostering establishment of disposal facilities. On the other hand, active implementation of decommissioning is not necessarily subject to the availability of a waste disposal site. The Greifswald project is one example of decom project where decom waste are being stored on site.

16 National programmes of radioactive waste management Member States shall ensure that consideration is given to physical, chemical and radiological characteristics of decommissioning wastes when their waste management system is being developed and implemented. This is especially important when planning the availability of adequate disposal capacity.

17 What should a decommissioning plan contain? - Estimate of waste amounts based on decom strategy incl operational waste at final shutdown - establish criteria for categorizing wastes based on national policy - define waste routes from generation to disposal incl.: - procedures and process flow for handling, conditioning, packaging, storage and disposal - QA procedures for assay, categorization, release

18 What should a decommissioning plan contain? (ctd) In a decommissioning project, the waste management plan is an integral part (or an associated document) of the overall decommissioning plan.

19 Specifics of decom wastes impacting their management and disposal Large volumes over a short timespan; Unusually large objects (e.g. reactor vessel), intact removal; Materials of unusual nature (graphite, sodium, transformer oils, decontaminant solutions); Toxic (e.g. asbestos) or mixed wastes;

20 Specifics of decommissioning wastes (ctd) Possibly unacceptable for near-surface disposal (e.g. highly activated or alphacontaminated items). Low and very low radioactive concentrations (difficult & time-consuming measurements for clearance) Note: Careful planning applied to the design, construction operation and decommissioning can reduce waste volumes dramatically

21 Specific WTS tasks on decom waste management Treatment, conditioning etc ( to be described in another presentation) Disposal ( to be described in another presentation)

22 International Action Plan on Decommissioning of Nuclear Facilities (approved by BOG, June 2004; GC, Sep 2004)

23 Tasks of Action Plan. 6 Review options for the management/disposal of radioactive waste from decommissioning taking into account special technical and safety problems

24 Summary Waste management is an orderly, phased, final step in decommissioning of a nuclear facility Planning for decommissioning waste management should be an on-going process and should be integrated within the entire decommissioning process Numerous IAEA reference documents are available Failing to plan is planning to fail