1. 1 G. Cambi, D.G. Cepraga, M. Frisoni Enea & Bologna University Team OSIRIS neutronic and activation simulation with Scalenea-ANITA in support of PACTITER/CORELE analyses Pactiter/Corele meeting January 25-26, 2005 Cadarache

2. 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 Enea & Bologna University Team

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

4. 4 Neutronic schematization Enea & Bologna University Team Region 1 One homogeneous zone (z1) z1 U235, U238, H 2 O, Al Region 2 Nine homogeneous zone (z2 to z10) z2, z3, z5, z7 90% H 2 O, 10% Steel z4, z6, z8 Steel (AISI 316) z9, z10 H 2 O 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) :  f (E>1 MeV)  epith (0.1 MeV<E<1 MeV)  th (E<0.1MeV) Attention is focused on the Region 2 where 4 test steel tubes (in water box 010) are irradiated for 8 hours

5. 5 ENEA neutronic simulation 1 Input data considered A (from integrated dose values Jan. 2004)  th = 1.9E+12 n/cm 2 s E th < 0.1 MeV  f = 2.4E+11 n/cm 2 s E f > 1 MeV B (updated simulation by Rozemblum Nov. 2004)  th = 2.25E+12 n/cm 2 s  f = 5.0E+11 n/cm 2 s C (older – 2001 - OSIRIS data )  th = 2.65E+12 n/cm 2 s  f = 3.5E+11 n/cm 2 s Parameter used to choose zone for tubes irradiation in region 2 I =  f /  th I A = 0.126 I B = 0.222 I C = 0.132 zone 5 zone 2 zone 3 Enea & Bologna University Team

6. 6 ENEA neutronic simulation 2 Enea & Bologna University Team Example of the procedure used to select the zone for neutron flux spectra definition

7. 7 Activation calculation Input data considered Test tubes data Average tube mass = 127 g SS 316L density = 8.10 kg/dm 3 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 0.031 Irradiation conditions Duration length = 8 hours Enea & Bologna University Team Others data needed Neutron flux spectra and total neutron flux for irradiation Neutron flux spectra (174 groups) in zones 2, 3, 5 (based on the parameter I) have been considered Total neutron flux zones 2, 3, 5 (n/cm 2 s)  tot  z2 = (  tot /  th ) z2 x  th (B) = 3.14E+12  tot z3 = (  tot /  th ) z3 x  th (C) = 3.27E+12  tot z5 = (  tot /  th ) z5 x  th (A) = 2.31E+12

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

9. 9 Conclusions and …… Enea & Bologna University Team  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. 10 …… future work Enea & Bologna University Team A more refined neutronic simulation could be obtained with SCALENEA if the following data will be available: Experimental total neutron flux for the test tubes irradiation zone More defined experimental data on neutron fluxes (i.e. thermal, epithermal, and fast neutron fluxes) Measures (fluxes and activity) uncertainties