Molten Chloride Reactor Experiment Nuclear Data ......Molten Chloride Reactor Experiment (MCRE) 3...

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Molten Chloride Reactor Experiment Nuclear Data Uncertainty Analysis and Needs

Tommy Cisneros

Copyright© 2021 TerraPower, LLC. All Rights Reserved.

The MCFR roadmap includes non-nuclear and nuclear facilities

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PresenterPresentation NotesFrom MCRE-ENG-PRSNT-0002


Molten Chloride Reactor Experiment (MCRE)

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Molten Chloride Reactor Experiment – Southern CompanyServices, Inc (Birmingham, AL) will lead a project to design,construct and operate the Molten Chloride Reactor Experiment(MCRE) – the world’s first critical fast-spectrum salt reactorrelevant to TerraPower’s Molten Chloride Fast Reactor.

[1] Energy Department (2020)


Nuclear Data Uncertainty is Important to MCRE Design

• Excess reactivity mitigates ND uncertainty• Control worth mitigates ND uncertainty• Uncertainty Covariance Data defines which benchmarks are

representative to the MCRE

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MCRE Will Demonstrate Novel Neutronic Features

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• Liquid Chloride Fuel Salt– Moving Fuel Salt– Chlorine in high importance

region of the system• Magnesium Oxide Reflector

– Scattering on MgO reflects neutrons and moderates fast neutrons

• Plutonium Fuel– No Uranium in Fuel Salt Mix


Nuclear Data Uncertainty

• To quantify nuclear data induced uncertainties of a design, covariance matrices may be convoluted with the sensitivity vectors via the “sandwich formula” to produce the desired uncertainty of integral parameters R.

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Δ𝑅𝑅2 = 𝑆𝑆𝑅𝑅𝑇𝑇𝐷𝐷𝑆𝑆𝑅𝑅

SR Sensitivity of Integral Parameter RD Covariance Matrix

[2] Salvatores (2008)


Sensitivity is Calculated with MCNP6 and ARMI® software

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[4] Kiedrowski (2013)

[3] Touran (2016)

ksens

[5] Cheatham (2013)


ENDF/B VIII.0 Covariance Data Processed with NJOY

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Fissionable Isotopes: nu, (n, fission), (n, gamma), (n, 2n), elastic scattering, inelastic scattering, chi

Non Fissionable Isotopes: (n,gamma), elastic scattering, inelastic scattering, (n,proton)*

[6] Macfarlane (2017)

[7] Brown (2018)

*35Cl (n,p) reaction is an important neutron loss mechanism in chloride salt systems


239Pu Drives the known ND Uncertainty: ~900 pcm

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Nuclide Reaction Uncertainty (pcm)239Pu Fission 72124Mg Elastic Scat 378239Pu Nu 251239Pu (n,γ) 241239Pu Inelastic Scat 8523Na Elastic Scat 7558Ni Elastic Scat 68

… … …

Total 908


INDEN Project is Advancing Nuclear Data of Many Uncertainty Drivers for the MCRE

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[8] Capote (2020)

INDEN is the follow up to the CIELO Pilot Project that produced several evaluated data files adopted by ENDF/B-VIII.0 and

• INDEN (actinides): 239Pu• INDEN (structural materials): 58Ni• INDEN (light elements): 16O

PresenterPresentation NotesCapote, R; Trkov, A; Pigni, M, T; Neudecker, D; Noguere, G; Bernard, D “Improving evaluation in the RRR for Pu239” https://www-nds.iaea.org/index-meeting-crp/TM-INDEN-2019/docs/Capote-ResAct-INDEN.pdf

RRR (resolved resonance region)

Development of n 239Pu eval with IAEA INDENA new INDEN p10 file (WIP) features:Softer thermal prompt fission neutron spectra (Chi)Updated resonance parameters compatible with softer ChiExecellent agreement with IAEA standard @thermal point

Pu239 evaluation comes from WPEC/SG34

There is still a problem with the 15eV resonance interference

CEA to do in 2020 on 239PuAdd Mosby data in the CONRAD analysis when available on EXFORSimultaneous analysis of XS and nu by introducing (n,gamma fission) reaction and class II states in the RRR analysis

239Pu was focus on high energy in CIELO/ENDFVIII.0 – it underpredicts thermal soluaiton benchmarks – INDENs is working on this


24Mg (mt=2) May be an Opportunity to Reduce Uncertainty in the MCRE

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• Given the limited attention, significant uncertainty and novel application – this analysis has highlighted 24Mg as an opportunity for updates– 24Mg data was ported from

JENDL-3.2 (1995)– Covariance data was added

from the lo-fidelity covariance project (2011)

PresenterPresentation NotesMg is an impurity in many benchmarks in the IHECSB for several of the Pu Metal Benchmarks – but not to my knowledge of a dedicated experiment


35Cl (n,p) Gaps May Result in Uncertainty Biased Low

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[9] Zerkin

If you assume 100% cov >1.2MeV:35Cl (n,p) σ: 30 -> 1472 pcmTotal σ : 900 -> 1729 pcm

PresenterPresentation NotesLee made a new measurement -- it looks like it’s a resonance and there’s a discrepancy of 85% between the ENDF/B VIII.0 and its in the meat of the sensitivity


Recent Nuclear Data Experiments for 35Cl (n,p)

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[10] Batchelder (2019)

[11] Praena (2017)

[12] Ogállar (2019)

PresenterPresentation NotesBerkeley:Measured the 35Cl (n,p) and 35Cl (n,alpha) 2.42-2.74 MeV energy range. Neutrons where generated with (D(D,n)3He reactions at 100keV energies are sampled at different neutron energy with different positions. Beta decays of activation products of different reactions (35S and 32P for n,p and n,alpha) were used to determine the activation production and thereby the cross section. This teams’ results differ significantly from the ENDFVIII data.

Universidad de Granada / CERN.Interested in 35Cl (n,p) as part of Neutron Capture Therapy in Brain system – they also need n,p and n,gamma cross sections with better uncertainty. They are performing Time of Flight measurements to determine (n,gamma) and (n,p) nuclear cross section at CERN. As of early (2019) they had preliminary results of 35Cl (n,p) up to .1 MeV with the intent to extend into the range of 500keV to 1 MeV. Under analysis as of May 2020.

INLHas proposed performing an oscillation experiment where the flux to a sample will be filtered to closely match the fast spectrum of an MCFR reactor, but the transient oscillatory nature of the experiement will enable to the team to make precise differential reactivity worth measurements


Conclusions

• The MCRE Nuclear Data Uncertainty is 900 -1700 pcm• The known MCRE Nuclear Data Uncertainty is driven by 239Pu• 35Cl (n,p) reaction has been identified as a need for chloride MSRs

– Total ND Uncertainty increases from 900-1700 if covariance is assumed above 1.2 MeV

– The research community is collecting new experimental data– New data should be integrated into new evaluations for cross

sections and uncertainty• MCRE S/U highlighted 24Mg scattering as an opportunity for

advancement.• Focus of INDEN aligns well with 239Pu uncertainty in MCRE

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References

1. Energy Department’s Advanced Reactor Demonstration Program Awards $30 Million in Initial Funding for Risk Reduction. (2020, December 16). Department of Energy. https://www.energy.gov/ne/articles/energy-department-s-advanced-reactor-demonstration-program-awards-30-million-initial

2. Salvatores, M. (2008). OECD/NEA WPEC subgroup 26 final report: Uncertainty and target accuracy assessment for innovative systems using recent covariance data evaluations (No. 6410). NEA Tech. Rep.

3. Touran, N. W., & Yang, J. (2016, May). Sensitivities and uncertainties due to nuclear data in a traveling wave reactor. In Proc. Int. Conf. PHYSOR4. Kiedrowski, B. C. (2013). MCNP6. 1 k-Eigenvalue sensitivity capability: a user’s guide (No. LA-UR-13-22251). Los Alamos National Lab.(LANL),

Los Alamos, NM (United States).5. Cheatham, J., Truong, B., Touran, N., Latta, R., Reed, M., & Petroski, R. (2013, July). Fast reactor design using the advanced reactor modeling

interface. In International Conference on Nuclear Engineering (Vol. 55799, p. V002T05A072). American Society of Mechanical Engineers.6. Macfarlane, R., Muir, D. W., Boicourt, R. M., Kahler III, A. C., & Conlin, J. L. (2017). The NJOY Nuclear Data Processing System, Version 2016 (No.

LA-UR-17-20093). Los Alamos National Lab.(LANL), Los Alamos, NM (United States).7. Brown, D. A., Chadwick, M. B., Capote, R., Kahler, A. C., Trkov, A., Herman, M. W., ... & Zhu, Y. (2018). ENDF/B-VIII. 0: The 8th major release of

the nuclear reaction data library with CIELO-project cross sections, new standards and thermal scattering data. Nuclear Data Sheets, 148, 1-142.

8. Capote, R., & Trkov, A. (2020, December 9). INDEN - International Network of Nuclear Data Evaluators. IAEA Nuclear Data Services. https://www-nds.iaea.org/INDEN/

9. Zerkin, V. (n.d.). Evaluated Nuclear Data File (ENDF). IEAE Nuclear Data Services. Retrieved January 7, 2021, from https://www-nds.iaea.org/exfor/endf.htm

10. Batchelder, J. C., Chong, S. A., Morrell, J. T., Unzueta, M., Adams, P., Bauer, J. D., ... & Lewis, A. M. (2018). Evidence of non-statistical properties in the 35Cl (n, p) 35S cross section. Bulletin of the American Physical Society, 63.

11. Praena, J., Porras, I., Lederer-Woods, C., & Sabaté-Gilarte, M. (2017). The 14N (n, p) 14C and 35Cl (n, p) 35S reactions at n_TOF-EAR2: dosimetry in BNCT and astrophysics (No. CERN-INTC-2017-039).

12. Ogállar, F., Sabaté-Gilarte, M., Torres-Sánchez, P., Porras, I., Praena, J., Quesada, J. M., ... & Garg, R. (2019). Nuclear data program for Neutron Capture Therapy at the n TOF facility at CERN. IL NUOVO CIMENTO, 100(137), 42.

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BACKUP

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Commercial Power MCFR reactors are much more sensitive to 35Cl

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Negative reactivity of 35Cl can be mitigated by chlorine enrichment or reducing leakage

MCFR-C 500-1200 MWe

PresenterPresentation NotesThe ~5% sensitivity for the natural chlorine case is on the order of U238 fissions in this system

Less fissile content and lower leakage core – mean the neutrons have more of a chance to interact with the chlorine.


PSI is updating Ni Evaluations in new releases of TENDL

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Rochman, D; Koning, A; and Dzysiuk, N “TENDL-2019 and the Ni isotopes: what to expect” (2019) IAEA Nuclear Data Serviceshttps://www-nds.iaea.org/index-meeting-crp/CM-INDEN-IV-2019/docs/Rochman_vienna.inden.december.2019.pdf

https://tendl.web.psi.ch/tendl_2019/neutron_file/Ni/Ni058/lib/endf/plots/n-Ni058-endfb8.0-comp.pdf

Paul Scherrer Institute (PSI) is updating an evaluation of Ni as part of the INDEN (Structural Materials) effort.

PresenterPresentation NotesThere is bias between 1e-4 MeV and 0.1 MeV between resonances and no nuclear data between 0.1 MeV and 14 MeV

Molten Chloride Reactor Experiment Nuclear Data Uncertainty Analysis and NeedsThe MCFR roadmap includes non-nuclear and nuclear facilitiesMolten Chloride Reactor Experiment (MCRE)Nuclear Data Uncertainty is Important to MCRE DesignMCRE Will Demonstrate Novel Neutronic FeaturesNuclear Data UncertaintySensitivity is Calculated with MCNP6 and ARMI® softwareENDF/B VIII.0 Covariance Data Processed with NJOY239Pu Drives the known ND Uncertainty: ~900 pcmINDEN Project is Advancing Nuclear Data of Many Uncertainty Drivers for the MCRE24Mg (mt=2) May be an Opportunity to Reduce Uncertainty in the MCRE35Cl (n,p) Gaps May Result in Uncertainty Biased LowRecent Nuclear Data Experiments for 35Cl (n,p)ConclusionsReferencesBackupCommercial Power MCFR reactors are much more sensitive to 35ClPSI is updating Ni Evaluations in new releases of TENDL

Molten Chloride Reactor Experiment Nuclear Data ......Molten Chloride Reactor Experiment (MCRE) 3...

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