The paper presents the ITER Vacuum Vessel (VV) contact dose build up evaluation from start to end of the machine life (expected to occur after about 22 years of operations, corresponding to an average neutron fluence of 0.5 Mwa/m2 on the First Wall). These results can be used as a contribute to estimate the overall ITER dismantling cost, in the case that this take place before the planned end of machine operations. No estimate is performed on the tritium plasma facing materials absorption and contamination. Contact dose build up calculation have been performed considering the reference design used for ITER Generic Site Safety Report (GSSR). Results are given for the inboard and outboard VV regions (and for both the front and rear 316L(N)-IG walls) in the radial equatorial plane. The average neutron power load (NPL) on the plasma facing components is 0.57 MW/m2. Study cases for different averaged FW neutron fluence (from 10-6 to 0.5 MWa/m2) have been performed by defining suitable multi-steps irradiation scenarios, based on the SA1 reference irradiation scenario (0.5 MWa/m2) used for ITER GSSR. For all the cases the calculation have been done by acting only on the irradiation period duration in order to kept unchanged the neutron flux distributions with respect to the SA1 irradiation scenario. Some short continuous irradiation scenarios have been also assessed to analyze the initial ITER D-T operation phase. Calculated values are given for the end of each one of the irradiation scenarios and for various cooling times, up to 1000 years. The Sn calculation sequence SCALENEA-1 (with the FISPACT-99 activation code) has been used for the analysis. For quality assurance purposes, some calculations have been also performed using the ANITA-2000 activation code. The result point out that after only 20 seconds of irradiation at the average NPL the contact dose of the most activated VV zone (i.e. the outboard region, front wall), the hands-on limit of 25 microSv/h is reached (for 1 month cooling time), requiring remote handling operations for that component.
Vacuum vessel contact dose build-up from start to end of ITER operations / G. Cambi; D.G. Cepraga; M. Frisoni; F. Carloni; A. Chiasera. - STAMPA. - 1:(2004), pp. 156-159. (Intervento presentato al convegno 20th Symposium on Fusion Engineering SOFE tenutosi a Bahia Resort Hotel, San Diego, CA, USA nel October 14 -17, 2003).
Vacuum vessel contact dose build-up from start to end of ITER operations
CAMBI, GILIO;CARLONI, FRANCA;
2004
Abstract
The paper presents the ITER Vacuum Vessel (VV) contact dose build up evaluation from start to end of the machine life (expected to occur after about 22 years of operations, corresponding to an average neutron fluence of 0.5 Mwa/m2 on the First Wall). These results can be used as a contribute to estimate the overall ITER dismantling cost, in the case that this take place before the planned end of machine operations. No estimate is performed on the tritium plasma facing materials absorption and contamination. Contact dose build up calculation have been performed considering the reference design used for ITER Generic Site Safety Report (GSSR). Results are given for the inboard and outboard VV regions (and for both the front and rear 316L(N)-IG walls) in the radial equatorial plane. The average neutron power load (NPL) on the plasma facing components is 0.57 MW/m2. Study cases for different averaged FW neutron fluence (from 10-6 to 0.5 MWa/m2) have been performed by defining suitable multi-steps irradiation scenarios, based on the SA1 reference irradiation scenario (0.5 MWa/m2) used for ITER GSSR. For all the cases the calculation have been done by acting only on the irradiation period duration in order to kept unchanged the neutron flux distributions with respect to the SA1 irradiation scenario. Some short continuous irradiation scenarios have been also assessed to analyze the initial ITER D-T operation phase. Calculated values are given for the end of each one of the irradiation scenarios and for various cooling times, up to 1000 years. The Sn calculation sequence SCALENEA-1 (with the FISPACT-99 activation code) has been used for the analysis. For quality assurance purposes, some calculations have been also performed using the ANITA-2000 activation code. The result point out that after only 20 seconds of irradiation at the average NPL the contact dose of the most activated VV zone (i.e. the outboard region, front wall), the hands-on limit of 25 microSv/h is reached (for 1 month cooling time), requiring remote handling operations for that component.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
