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Zentralabteilung Forschungsreaktoren

Zentralabteilung Forschungsreaktoren. ANALYSIS OF THE ACTIVITY INVENTORY FOR THE DECOMISSIONING PLAN OF THE GERMAN FRJ-2 RESEARCH REACTOR R. NABBI, P. BOURAUEL, G. DAMM. Contents - The German FRJ-2 Research Reactor Operation and Decommissioning Distribution of Neutronflux and activity

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Zentralabteilung Forschungsreaktoren

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  1. ZentralabteilungForschungsreaktoren ANALYSIS OF THE ACTIVITY INVENTORY FOR THE DECOMISSIONING PLAN OF THE GERMAN FRJ-2 RESEARCH REACTOR R. NABBI, P. BOURAUEL, G. DAMM • Contents • - The German FRJ-2 Research Reactor • Operation and Decommissioning • Distribution of Neutronflux and activity • Geometrical Nodalization (MCNP) • ORIGEN Model and Calculations • - Effects of geometrical inhomogenities • - Results and Summary

  2. ZentralabteilungForschungsreaktoren The main design data of the FRJ-2 Research Reactor • Type: Tank • Operation: 1962 - 2006 • Thermal Power: 10/15/23 MW • Moderator / Coolant: D2O (Heavy Water) • Vertical experimental tubes: 25 inside core and 25 inside reflector • Horizontal experimental tubes: 10 inside D2O and 21 inside graphite reflector • Neutron flux: • core max.: 3,2*1014 1/(cm2s) • reflector max.: 2,6*1014 1/(cm2s)

  3. ZentralabteilungForschungsreaktoren MCNP: Arrangement of the beam tubes in the structures Nab-April2007

  4. ZentralabteilungForschungsreaktoren MCNP: FRJ-2 model with the nodalized reactor core

  5. ZentralabteilungForschungsreaktoren MCNP: FRJ-2 model with the nodalized reactor core

  6. 3-d Distribution of the n-flux in the reactor core midplane and fuel element(MCNP-BURN) Core Fuel element Core center

  7. ZentralabteilungForschungsreaktoren MCNP: Nodalization of the whole reactor block

  8. ZentralabteilungForschungsreaktoren Cd-layer Visualization of the streaming effect

  9. ZentralabteilungForschungsreaktoren MCNP: Distribution of thermal N-flux

  10. ZentralabteilungForschungsreaktoren Neutron flux distribution in the structures

  11. Detailed neutron flux distribution in the structure

  12. ZentralabteilungForschungsreaktoren Distribution of N-flux above the Cd-layer Nab-April2007

  13. ZentralabteilungForschungsreaktoren Distribution of thermal N-flux in the steel tank

  14. ZentralabteilungForschungsreaktoren Total activity in the structures of the reactor

  15. ZentralabteilungForschungsreaktoren Nuclide activity in different structures after 5 years cooling time

  16. ZentralabteilungForschungsreaktoren Distribution of the total activity in radial structures

  17. ZentralabteilungForschungsreaktoren • Summary & Conclusions • A sophisticated MCNP model is generated on the basis of detailed material composition and geometrical design data • Using the MCNP model the neutron flux was determined with a high level of accuracy and low standard deviations • Using ORIGEN, the activity inventory in different components could be • determined. The calculations resulted in a detailed activity map allowing • The determination of the low and high level activity zones • Reduction of waste material mass and volume • Optimum dismantling process with minimum radiation effect • The main source of activity are H3, Fe55 and Co60 resulting from the activation of impurities

  18. Horizontal cut view of the whole reactor block Therm. Power Central FE

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