WP5 Graphite

The objective of WP5 Graphite was to understand the factors determining release of ¹⁴C from irradiated graphite (i-graphite) under geological disposal conditions. This was achieved through:

• determining the ¹⁴C inventory and concentration distribution in i-graphites and factors that may control these;
• measuring the rate and speciation of ¹⁴C release to solution and gas from i-graphites in contact with aqueous solutions;
• determining the impact of selected waste treatment options on ¹⁴C release and relating this to the nature of ¹⁴C in i-graphite.

The published reports are:

1. Review on 14C leaching in French i-graphite (restricted to the partners of the CAST project)
2. Annual progress report on WP5 - year 1
3. Report on graphite categories in the RBMK reactor
4. Definition of the scientific scope of leaching experiments and definition of harmonised leaching parameters
5. Review of current understanding of inventory and release of C14 from i-graphites
6. Annual progress report on WP5 - year 2
7. Report on C14 distribution in irradiated graphite from research reactor VVR-S
8. Synthesis report on 14C speciation in solution and gas from French graphite waste
9. Annual progerss report on WP5 - year 3
10. Final report on C14 release and inorganic/organic ratio in leachated rfom TRIGA irradiated graphite
11. Report on exfoliation processes and on structural and morphological properties of graphite
12. Final evaluation of leach rates of treated and untreated i-graphites
13. Vadellos 1 graphite compilation report: thermal decontamination and IGM waste form
14. Release of C14 from irradiated VVR-S graphite to solution and gas phase
15. Final report on 14C leaching from Vandellos 1 graphite
16. Report on effect of removal of surface layer of graphite on C14 release and behaviour
17. Report on modelling of 14C inventory in RBMK reactor core
18. Report on 13C behaviour under irradiation in HOPG (model graphite)
19. Final report on results from WP5

The last General Assembly Meeting has been held in France (Lyon) in January 2018 as the CAST Final Symposium. Presentations from this work package were:

Overview of main WP5 outcomes, summary and conclusions - Simon Norris (NDA)

Ion irradiation used as surrogate for neutron irradiation to understand nuclear graphite evolution during reactor operation : consequence for long lived radionuclide behaviour - Nelly Toulhoat (IPNL)

¹⁴C in TRIGA irradiated graphite and its release under alkaline conditions - Crina Bucur (RATEN ICN)

Oldbury graphite for RWM - Steve Swanton (Wood)

New concept and instruments for ¹⁴C measurements in i-graphite - Gérard Laurent (Integrated Nuclear Engineering Solutions)

Posters that were presented and are relevant for this workpackage were:

C-14 enrichment of surface deposits in Oldbury reactor core graphite

The measurement of impurity of RBMK-1500 graphite

¹⁴C leaching and speciation studies on irradiated graphite from Vandellós I NPP

A study of graphite from RBMK-type reactors 

Characterization of ¹⁴C in neutron irradiated RBMK-1500 graphite

Contact: Simon Norris