PHYSOR 2016 – Unifying Theory and Experiments in the 21st Century, Sun Valley Resort, Sun Valley, Idaho, USA, May 1 – 5, 2016, Extended summary

BATEMAN 1910-2016: revisited, enhanced and generalized

J-Ch. Sublet*, M. Fleming, M. R. GilbertUnited Kingdom Atomic Energy Authority, Culham Science Centre

Abingdon OX14 3DB, United Kingdomjean-christophe.sublet@ccfe.ac.uk

michael.fleming@ccfe.ac.ukmark.gilbert@ccfe.ac.uk

J. W. Eastwood, J. G. MorganCulham Electromagnetics Ltd, Culham Science Centre

Abingdon OX14 3DB, United Kingdom james.eastwood@culhamem.co.uk

guy.morgan@culhamem.co.uk

Extended summary

1. Introduction

The inventory code FISPACT-II, when connected to the nuclear data libraries TENDL-2014, ENDF/B-VII.1, JENDL-4.0u or JEFF-3.2 forms a powerful modern system for modeling activation, transmuta-tion processes and simulating radiation damage sources terms. The system has extended nuclear data forms and new software, FISPACT-II, written in object-style Fortran with a well-established numerical solver, to provide new and enhanced capabilities for predictions of activation, transmutation, depletion, burn-up, decays and source terms. The new FISPACT-II code has allowed the implementation of many more features including: incident particle energy range up to GeV; incident particles types (alpha, gamma, proton, deuteron and neutron); and additional neutron physics such as: self-shielding effects, temperature dependence, thin and thick target yields, pathways analysis, sensitivity and error estimation using cross section covariance data. These capabilities satisfy the needs of many applications: nuclear fission and fusion, materials sciences, accelerator physics, astrophysics, isotope production, waste man-agement and many more.

In parallel, the maturity of modern-technology-generated, truly general-purpose libraries such as TENDL-2014, encompassing thousands of target isotopes, the evolution of the ENDF format and the capabilities of the latest generation of processing codes PREPRO-2015, NJOY-2012 and CALENDF-2010 have allowed the FISPACT-II code to be fed with more robust, complete and appropriate data forms: resonance parameters, group cross-sections with covariance, probability tables in the resolved and unresolved resonance ranges, pka recoil spectra (primary knock on atom), prompt and decay heat-ing kerma (kinetic energy release in material), dpa (radiation damage energy production), gas and ra-dionuclide production supplemented with 24 decay types out of the different decay data libraries UKDD-12, ENDF/B-VII.1/DS, JENDL/FPD-2011 or JEFF-3.1.1/RDD. All such data for the five most important incident particles are placed in evaluated data tables with incident energy of up to 200 MeV. The spontaneous and neutron induced fission yields libraries GEF-4.2, JEFF-3.1.1/FY, ENDF/B-VII.1/FY and JENDL/FPY-2011can all be read for any fission simulations. Libraries of biological, clearance and transport indices following the International Commission on Radiological Protection guidelines are provided for all radioactive nuclei that can be produced by either reaction or decay. The

*CCFE is the research branch of the United Kingdom Atomic Energy Authority http://www.ccfe.ac.uk/

J-Ch. Sublet et al.

resulting code and data system includes many new features and enhancements. It has now been exten-sively tested, and also benefits from the feedback from wide-ranging validation and verification activi-ties performed for a variety of applications: fusion, fission, astrophysics and medical.

2. FISPACT-II

FISPACT-II [1] is a completely new inventory code engineered: designed, written, tested and verified over a period of five years. It is written in object-style Fortran-95, uses dynamical memory allocation and so may be readily adapted to any energy group structures. It contains three major subsystems for handling (1) nuclear data reduction and manipulation, (2) assembling and solving the rate equations for the inventory and (3) computing pathways, quantifying and propagating uncertainties. At present, it works with every ENDF-6 formatted nuclear data libraries included in the simulation platform: TENDL-2014, ENDF/B-VII.1, JENDL-4.0u, JEFF-3.2 or EAF-2010. It is now a powerful and practical inventory-transmutation engineering prediction tool that possesses the following functionalities:

Extraction, reduction, manipulation and storage of nuclear and radiological data forms from the nuclear data library files: cross section, recoil spectra, discrete decays lines

Construction and solution of the rate equations to determine the time evolution of the inventory in response to different irradiation scenarios. These scenarios include:

A decay or cooling-only calculation; single irradiation pulse followed by cooling Multiple irradiation pulses where only flux amplitudes changes, followed by cooling Multi-step irradiation where flux amplitude, flux spectra and cross-sections may change

followed by cooling Multiple incident-particle simulation

Computation and output of derived primary and secondary radiological quantities Subsidiary calculations to identify the key reactions and decays, associated uncertainty, and to

assess the quality of the predictions. The five main subsidiary items are: Pathways, routes of production analysis Uncertainty quantification and propagation from pathways Reduced model calculations Monte-Carlo sensitivity and uncertainty simulations Library substitutions

3. Nuclear data libraries

The new code system has benefited from the maturation of modern nuclear data libraries, now expected to include a full set of variance-covariance information and the amalgamation of the capabilities of the most recent release of three processing codes PREPRO, NJOY and CALENDF. Although the nuclear data forms available to the FISPACT-II inventory code are complete and complex in nature they mainly rely on an ENDF-6 format frame structure and this tremendously simplifies all further utilitarian opera-tions such as plotting, comparison, concatenation and data manipulation in general. The nuclear data forms encompass group cross-section (fine 660 groups below 30 MeV), resonance parameters with co-variance, probability tables, recoil daughter and particles spectra matrices, spontaneous and particles induced fission yields, and decay data, as well as biological, clearance and transport indices as depicted schematically in Figure 1.

4. Verification, validation and benchmarking

A unique assortment of verification and validation efforts have been undertaken for FISPACT-II, using both fission [2,3,4] and fusion [5,6] decay heat experiments, integro-differential verification of the nu-

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BATEMAN 1910-2016: revisited, enhanced and generalized

clear data used for a variety of neutron spectra [7], astrophysical Maxwellian-averaged cross-sections with fully broadened/collapsed data [8] and a combination of statistical and non-threshold verifications for the integrated nuclear data [9]. Figures 2 to 4 exemplify some of the platform capabilities.

Figure 1. Flow diagram of the input and output streams (magenta) of the inventory code FISPACT-II

Figure 2. Selection of figures from [4] showing (1) fast-reactor total and gamma heat compared with

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simulations using a variety of nuclear data sources and 400keV nFY files (2) fission pulses with various incident-neutron energies from thermal to 20MeV from GEF-4.2.

Figure 3. Selection of figures from [7] showing (clockwise) (1) spectroscopic decay heat simulation and measurements from FNG copper irradiation, (2) differential Sc45(n,2n) of TENDL-2014 against EXFOR, (3) C/E comparisons for Cr52(n,2n) integral cross sections and (4) global comparison of C/E values for all integral values using TENDL-2014 and EAF-2010 libraries.

Figure 4. Selection of figures from [8] showing (1) broadened differential Cr51 (n,g) cross sections with reaction rate superimposed and (2) C/E of temperature-dependent MACS for Cr51.

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BATEMAN 1910-2016: revisited, enhanced and generalized

5. Conclusion

The new and advanced features of the FISPACT-II with its libraries provide robust simulation capabili-ties, which can be generally applied to any nuclear system. By remaining general-purpose, code results can be used for various applications without compromising predictive power when moving between physical regimes. The utility of this approach can be seen in the fission pulse experiments, where par-tial gamma/beta heats are poorly simulated with legacy methods. While total heat was never badly pre-dicted due to compensations, local heating simulations (due to difference in gamma/beta heat diffusiv-ity) and other advanced applications could not be performed with accuracy.

Experimental results covering the decays and inventory benchmarking activities from fusion and fis-sion events are useful to probe the databases and can be used to develop simulation guidance and un-certainty quantification and propagation in decay heat and inventory predictions for all applications with the inventory code FISPACT-II and its attached libraries. The ability to read any and all nuclear data libraries, particularly the general-purpose TENDL and technological GEF-4.2 fission yields, af-fords a unique capability to probe and contrast data in the effort to increase nuclear data robustness for all applications.

This latest modern simulation platform is capable of meeting the present and future nuclear simulation requirements in terms of activation, transmutation, depletion, burn-up, decays, source terms and inven-tory, it can help probe the nuclear model code capabilities away from the valley of stability, interrogate nuclear observables and provide robust simulation capabilities for all applications.

REFERENCES[1] J-Ch. Sublet, J. W. Eastwood, and J. G. Morgan. The FISPACT-II User Manual. Technical Report

CCFE-R(11) 11 Issue 6, CCFE, 2014. http://www.ccfe.ac.uk/EASY.aspx[2] M. Fleming and J-Ch. Sublet. Decay data comparisons for decay heat and inventory simulation of

fission events. Technical Report CCFE-R(15)28 S1, 2015. http://www.ccfe.ac.uk/EASY.aspx[3] M. Fleming and J-Ch. Sublet. Fission yields comparisons for decay heat and inventory simulation

of fission events. Technical Report CCFE-R(15)28 S2, 2015. http://www.ccfe.ac.uk/EASY.aspx[4] M. Fleming and J-Ch. Sublet, Validation of FISPACT-II Decay Heat and Inventory Predictions for

Fission Events, Technical report CCFE-R(15)28, 2015. http://www.ccfe.ac.uk/EASY.aspx[5] J-Ch. Sublet and M. Gilbert. Decay heat validation, FISPACT-II & TENDL-2014, JEFF-3.2,

ENDF/B-VII.1 and JENDL-4.0 nuclear data libraries. Technical Report CCFE-R(15)25, 2015. http://www.ccfe.ac.uk/EASY.aspx

[6] M Gilbert, J-Ch Sublet, and R Forrest, Handbook of activation, transmutation, and radiation dam-age properties of the elements simulated using FISPACT-II & TENDL-2014; Magnetic Fusion Plants CCFE-R(15)26, Nuclear Fission Plants (PWR focus) CCFE-R(15)31, Nuclear Fission plants (HFR focus) CCFE-R(15)32, Nuclear Fission Plants (FBR focus) CCFE-R(15)33. http://www.c-cfe.ac.uk/EASY.aspx

[7] M. Fleming, J-Ch. Sublet and J. Kopecky. Integro-Differential Verification and Validation, FIS-PACT-II & TENDL-2014 nuclear data libraries. Technical Report CCFE-R(15)27, 2015. http://www.ccfe.ac.uk/EASY.aspx

[8] J-Ch. Sublet and M. Fleming. Maxwellian-Averaged Neutron-Induced Cross Sections for kT=1 keV to 100 keV, TENDL-2014, END/B-VII.1 and JENDL-4.0u nuclear data libraries. Technical Report CCFE-R(15)29, 2015. http://www.ccfe.ac.uk/EASY.aspx

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[9] M. Fleming, J-Ch. Sublet and J. Kopecky. Non-threshold and Statistical Verification and Valida-tion, FISPACT-II & TENDL-2014 nuclear data libraries. Technical Report CCFE-R(15)30, 2015.

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