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LEADER – WP 2 - Task 2.2 ALFRED - Further neutronic calculations: fuel inventory and 3 H production C. Petrovich (ENEA) Karlsruhe, November 21 st 2012

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Outline 1.Situation of the deliverables 2.Power deposition - update 3.Isotopic composition of the irradiated fuel 4. 3 H production (from ternary fission and Boron) 5.Conclusions

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- Deliverable D7 (issued March 2012) C. Petrovich, G. Grasso, C. Artioli, F. Rocchi, P. Sciora, D07 - Definition of the ETDR core and neutronic characterization ENEA-CEA - Rev.1 of D7 (draft expected by January 2013) - Deliverable D27 (to be issued. Draft expected by January 2013) ETDR core. Summary, synoptic tables, conclusions and recommendations 1. Situation of the deliverables

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4 Safety Rods 12 Control Rods 57 Fuel Assembly %(Pu+Am)=21.7% 114 Fuel Assembly %(Pu+Am)=27.8%) Core configuration (300 MWth) Total FA = 171 Dummy elements = 108 Inventory in tons (U / Pu / MA) BOL5.42 / 1.87 / BOC5.27 / 1.78 / EOC5.19 / 1.74 / 0.043

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2. Power deposition - update By materials By zone Due mainly to emission (from fission) part of the power is deposited outside the fuel pellets In the FA Pb by-pass: 0.4% of the total power (about 1.2 MW th ) Calculations by MCNPX

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3. Isotopic composition of the irradiated fuel Method: approximated batch approach. Batches (1/5 core) Irradiation time at EOC 1 st 1y 2 nd 2y 3 rd 3y 4 th 4y 5 th 5y average3y 5 batches and a refuelling of 1/5 of the core every year (1 cycle=1y). Since the residence time at EOC is 3y (at equilibrium), the whole core is burnt from fresh MOX fuel up to 3y to represent EOC. 2 codes used: 1. MCNPX (Los Alamos, transport code): detailed geometry and cross-sections, but 200 FP isotopes (selected for k eff and neutronic) 2. FISPACT (UKAEA, activation code): 2000 isotopes (fission yield data from JEF-2.2) but no accurate cross- sections. Best approach found: FISPACT with the cross-sections provided by MCNPX

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Fission Products: MCNPX vs FISPACT Average difference for the elements: 35% (from 2% to a factor of 2) The FP inventory at EOC in all FA is: 327 kg. Average fissions at EOC: 9.4 10 26

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Fuel composition: actinides calculated by MCNPX

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Fuel composition: some FP

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MCNPXFISPACT half life (s)grams diffBq I 127Stable7.2E+024.5E+02-38%0.0E+00 I E+038.5E-041.8E+15 I E+142.3E+031.6E+03-30%1.1E+10 I E+045.9E-024.9E-02-17%3.5E+15 I 130m5.4E+023.8E-042.3E+15 I E+057.1E+01 -1%3.2E+17 I E+031.2E+004.8E+17 I 132m5.0E+033.7E-032.3E+15 I E+041.5E+016.4E+17 I 133m9.0E+002.7E-059.4E+15 I E+037.0E-016.9E+17 I 134m2.2E+026.9E-039.7E+16 I E+044.2E+004.9E+00+17%6.3E+17 I E+011.0E-023.8E+17 I 136m4.5E+012.3E-031.5E+17 Iodium isotopes: MCNPX vs FISPACT

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MCNPXFISPACT half life (s)grams diffBq Xe126Stable2.5E-031.3E-03-46%0.0E+00 Xe E+061.5E-051.5E+10 Xe127m6.96E+016.1E-112.9E+09 Xe128Stable2.4E+011.7E+01-27%0.0E+00 Xe129Stable1.6E-011.4E-01-18%0.0E+00 Xe129m7.66E+055.3E-042.2E+12 Xe130Stable5.1E+014.1E+01-19%0.0E+00 Xe131Stable6.5E+036.8E+034%0.0E+00 Xe131m1.03E+062.8E+008.8E+15 Xe132Stable9.6E+031.1E+049%0.0E+00 Xe E+058.7E+019.3E+017%6.4E+17 Xe133m1.89E+051.2E+001.9E+16 Xe134Stable1.4E+041.5E+0411%0.0E+00 Xe134m2.90E-012.0E-062.1E+16 Xe E+046.9E+00 1%6.6E+17 Xe135m9.39E+023.4E-021.1E+17 Xe136Stable1.3E+04 3%0.0E+00 Xe E+024.5E-025.9E+17 Xe E+021.6E-015.5E+17 Xe E+016.5E-034.9E+17 Xenon isotopes: MCNPX vs FISPACT

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1. From ternary fission Chosen value: ~ 2 ~ fissions/s (from 300 MW th ) Conservately: ~ 2 atoms of 3 H/s and at EOC ~2 atoms of 3 H (in core) 4. 3 H production (1/2) [1] Janis (NEA –JEFF-3.1) [2] J.E. Tanner, An Overview of Tritium Fast Fission Yields, PNL-3563, UC-11, 1981 [3] J.E. Martin, Physics for Radiation Protection – A Handbook, Wiley-VCH, 2006 [4] O. Serot et al., New Results on Helium and Tritium Gas Production From Ternary Fission, AIP Conf. Proc. 769, 857 (2005) [5] Buzzelli, 1976 Thermal 3 H atoms/fission Fast 3 H atoms/fission ~ 2 [2]~ 1.4 [1] [4]~ 2 [2] ~ 2 [5] ~ 1.3 [3]

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2. From Boron -Tritium is also produced by 10 B(n,2 ) 3 H -Detailed calculation with MCNPX (for flux and spectrum), then FISPACT (activation calculation on B 4 C) -4 SR and 12 CR: 284 kg of B 4 C under avg neutron flux of 1.5 cm -2 s -1 -Results: collapsed 1-group cross-section of 10 B(n,2 ) 3 H: 2 mbarn 3 H atomsgramsBq after 1s 3.5 10 6 after 1y 1.1 after 40y 1.8 Total Ternary fissionFrom 10 Btotal Atoms of 3 H after 1y 6.3 contribution37%63%100% - Consistent with ref. 2, where ternary fission represents 25%-50% of 3 H production in FR 4. 3 H production (2/2) - After 20 years the 10 B of both SR and CR disappeared is about 18%

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Conclusions -Revision by January 2013 of the D7 (neutronic calculations) -By-pass power deposition: 0.4% -Fuel composition: MCNPX results are ok for order of magnitude, but not precise for specific isotopes. FISPACT results are more accurate. Complete isotope list of (MCNPX and FISPACT) has been provided to (all?) involved partners and will be included in rev.1 of D7. -Tritium production: 6.3 (fission) and 1.1 atoms (Boron) after 1y

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