G. Cambi, D.G. Cepraga, M. Frisoni Presented by L. Di Pace (ENEA C.R. Frascati)

1. KOM of the contracts TW5-TSS-SEA5.6., TW5-TSS-SEA5.5.D8-9 October 26, 2005 Cadarache OSIRIS neutronic and activation simulation with Scalenea-ANITA in support of PACTITER/CORELE analyses Task No. TW5-TSS-SEA4.1 G. Cambi, D.G. Cepraga, M. Frisoni Presented by L. Di Pace (ENEA C.R. Frascati)

2. Neutronic-activation analysis goals • Reaction rates for nuclear reaction relevant for PACTITER simulation of the activation of the corrosion products in CORELE loop • Activity of the AISI 316 tubes irradiated in OSIRIS reactor vs. cooling time (i.e. during different corrosion tests in CORELE loop): total values and relevant isotope values • Comparison of the SCALENEA-ANITA calculation results with experimental data and with CASTOR calculations

3. Calculation Tools SCALENEA-1 Calculation sequence Radiation transport analysis Code sequence: Bonami-Nitawl-XSDNRPM (from Scale) Neutron-gamma data library: Vitenea-E (174n-38g) based on ENDF/B-V and ENDF/B-VI Material activation analysis Activation code: ANITA-2000 Activation data library: EAF-2003

4. Neutronic schematization Region 1 One homogeneous zone (z1) z1 U235, U238, H2O, Al Region 2 Nine homogeneous zone (z2 to z10) z2, z3, z5, z7 90% H2O, 10% Steel z4, z6, z8 Steel (AISI 316) z9, z10 H2O With this schematization the neutron flux spectra (174 groups) has been calculated and collapsed to obtain three group n flux (same energy boundaries as chosen by OSIRIS team) : Ff (E>1 MeV) Fepith (0.1 MeV<E<1 MeV) Fth (E<0.1MeV) Attention is focused on the Region 2 where 4 test steel tubes (in water box 010) were irradiated for 8 hours

5. ENEA neutronic simulation1 Parameter used to choose zone for tubes irradiation in region 2 I = Ff / Fth Input data considered A(from integrated dose values Jan. 2004) Fth = 1.9E+12 n/cm2 s Eth < 0.1 MeV Ff = 2.4E+11 n/cm2 s Ef > 1 MeV B(updated simulation by Rozemblum Nov. 2004) Fth = 2.25E+12 n/cm2 s Ff = 5.0E+11 n/cm2 s C(older – 2001 - OSIRIS data ) Fth = 2.65E+12 n/cm2 s Ff = 3.5E+11 n/cm2 s IA = 0.126 IB = 0.222 IC = 0.132 zone 5 zone 2 zone 3

6. ENEA neutronic simulation2 Example of the procedure used to select the zone for neutron flux spectra definition

7. Activation calculation Neutron flux spectra (174 groups) in zones 2, 3, 5 (based on the parameter I) have been considered Input data considered Test tubes data Average tube mass = 127 g SS 316L density = 8.10 kg/dm3 SS 316L composition (mass%): Fe 67.4 Ni 11.2   Co 0.093  Cr 16.77  Mn 1.64  Mo 2.06  Cu 0.29 S 0.01   C 0.012   N 0.07  Si  0.4  P 0.031Irradiation conditions Duration length = 8 hours Total neutron flux zones 2, 3, 5 (n/cm2 s) Ftotz2 = (Ftot/Fth)z2xFth (B) = 3.14E+12 Ftotz3 = (Ftot/Fth)z3xFth (C) = 3.27E+12 Ftotz5 = (Ftot/Fth)z5xFth (A) = 2.31E+12 Others data needed Neutron flux spectraand total neutron fluxfor irradiation

8. Results and comparisons Activity (Bq) for a 127 g SS316L test tube (March 26, 2004) Calculated/experiment

9. Results and comparisons • For ANITA calculation the case C (z3) provides the lowest discrepancies with respect to the experimental data. • The reaction rates for the PACTITER relevant nuclear reaction have been calculated (for the three neutron spectra z2, z3, z5). • The activity (total and for each relevant isotope) have been calculated for the cooling times relevant for PACTITER/Corele simulation

10. Irradiated tube decay calculations in support of new PACTITER simulations To support new PACTITER runs, other activation calculation with ANITA-2000 have been performed. Calculations refer to cooling times evaluated since the irradiation in OSIRIS on 26/1/2004 (because no new irradiation in OSIRIS are foreseen at the moment).

11. Temperature Velocity Release rate ( mg / dm² / month ) Test Species °C m /s in part total Ni 4.7 ± 0.9 60 - 2 - 2 Co ( Co) 6 10 ± 1 10 22 ± 3 4.12 Fe 16. ± 3 ITER Cr 1 ± 0.4 150 2004 - 01 Ni 8.1 ± 0.7 - 1 - 1 Co 1 10 ± 0. 2 10 36 ± 2 1.09 Fe 27 ± 2 Cr 0.27 ± 0.12 Results of tubes decay calculations1 From CEA Tech. Report DTN/STRI/LTCD 04-020 (26 janvier 2005) Table 5 Part of Table 12

12. Results of tubes decay calculations2 At the present time, Cr-51 (from Cr) has decreased from four to five orders of magnitude, Co-58 (from Ni) of a factor ~100, Fe-59 (from Fe) of a factor ~1000 and Mn-54 (from Fe as well) of a factor ~3.

13. Results of tubes decay calculations3 • Considering the activity trapped in the resins for each nuclide during the 2004 CORELE experiments, Cr-51 and Fe-59 were not detected in the resins in tests 02 and 03 due to reduced release rate of their father, but to such minor extent to their decay. • The decay effect, after about two years from the irradiation, might cause difficulties in detecting radionuclides such as Co-58 and Fe-59. While Fe-59 can be replaced by Mn-54 for calculating Fe release rate, the inability in detecting Co-58, can cause to neglect the contribute of Ni to the overall material release rate.

14. …… future work • To check the specific activities calculated by PACTITER by repeating CORELE experiments simulation and calculating the resin activities accordingly (Task TW4-TSS-SEA 5.5) • Simulate the scheduled CORELE test at T=200 °C to estimate the duration required to get activity level into resins of main radionuclides (Mn-54, Co-60, Co-58) (Task TW5-TSS-SEA 5.5 D8) • To simulate, in case, a new irradiation in OSIRIS reactor if that would be retained necessary (Task TW5-TSS-SEA4.1)