ACAB. Inventory code for nuclear applications: User's Manual V. 2008

Transcription

1 ACAB software upgrade ACAB Inventory code for nuclear applications: User's Manual V Javier Sanz (1, 2), Oscar Cabellos (2,3), Nuria García-Herranz (2,3) December 2008 (1) Permanent Address: Departamento de Ingeniería Energética E.T.S. Ingenieros Industriales, UNED C/ Juan del Rosal 12, Madrid, Spain (2) Also member of: Instituto de Fusión Nuclear Universidad Politécnica de Madrid (UPM) C/ José Gutiérrez Abascal 2, Madrid, Spain (3) Permanent Address: Departamento de Ingeniería Nuclear E.T.S. Ingenieros Industriales de Madrid, Universidad Politécnica de Madrid C/ José Gutiérrez Abascal 2, Madrid, Spain

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3 ACAB Software upgrade ACAB. Inventory code for nuclear applications: User's Manual V.2008 J. Sanz, O. Cabellos, N. García-Herranz Summary of the contents This report presents the user s manual of the updated ACAB code. It starts with a general summary of the major features of ACAB (Section I), highlighting the capabilities included in the present version. After that, the report is divided in sections structured as follows: i) Firstly, we address the issue of the nuclear data libraries selected as starting point in preparing the libraries to be used directly by ACAB. Section II describes the main features of the selected libraries. ii) iii) iv) Secondly, the points considered are processing of libraries and libraries adapted to be directly read by ACAB. The processing activities are made by two codes: COLLAPS and PROCDECAY. In Section III we provide an overall description of such codes. The content of the data libraries employed by the updated ACAB code is described in Section IV. Thirdly, the input data file for driving ACAB calculations is dealt with in Section V. Main features are the ability to compute inventory-related quantities and assess uncertainties on the calculations. In order to handle the uncertainty output in a friendly way, a post-processing code named PROCACAB is described. Some example problems are discussed in Section VI, addressing scenarios of IFE conceptual reactors, fusion experimental facilities (NIF), fission applications, etc. Finally, regarding analysis of activation/transmutation results, one of the elements considered in the ACAB system to perform this task is described in Section VII: the updated version of the CHAINS code, aimed to provide possible pathways for the formation of particular nuclides.

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5 CONTENTS I.- Major features of ACAB... 1 Page II.- Selection of nuclear data libraries II.1.- Nuclear data libraries selected as starting point A.- Activation neutron cross section basic library: EAF_N_GXS B.- Decay data basic library: EAF_DEC C.- Fission yield data basic library: EAF_N_FIS D.- Cross section uncertainty data basic library: EAF_UN E.- Proton and Deuteron-induced cross section basic libraries: EAF_P_XS-2007 and EAF_D_XS II.2. Other nuclear data basic libraries A.- Activation cross section basic library FENDL/A B.- Decay data basic library FENDL/D C.- Fission yield data basic library JEF D.- Cross section uncertainty data basic library FENDL UN/A III.- Processing codes III.1.- Processing code COLLAPS III.2.- Processing code PROCDECAY IV.- Data libraries for ACAB and running ACAB V.- Input Description A.- Block # B.- Block # C.- Block # I

6 D.- Block # E.- Block # F.- Block # G.- Block # 7/ H.- Block # I.- Block # J.- Block # K.- Block # L.- Block # M.- Block # N.- Post-processing code PROCACAB VI.- Example problems A.- National Ignition Facility (NIF) target chamber B.- Fission products C.- Pulse irradiation scenarios. Restart options D.- Activation of target debris in NIF-type facilities. Feeding capability E.- Activation of blanket in Magnetic Fusion Energy F.- Transmutation and damage behaviour of materials irradiated in IFMIF G.- Activation induced by a proton beam H.- Proton-induced thick-target radionuclide activation VII.- Pathway analysis. CHAINS code VIII.- References II

7 LIST OF TABLES Table I.1. Capabilities of ACAB included in the current version...8 Table II.1. Reaction types included in EAF Table II.2. Sources for the cross section data included in EAF Page Table II.3. Fissionable nuclides with fission product yield data in EAF_N_FIS Table II.4. Reaction types included in FENDL/A Table II.5. Sources for the cross-section data included in FENDL/A Table II.6. Sources for the cross sections data of the important reaction sublibrary of FENDL/A Table II.7. FENDL/D-2.0: Modes of decay and number of ground state and isomeric state daughters produced in each mode...20 Table II.8. Sources for neutron-induced fission products yields in JEF Table III.1. Energy group boundaries for the Vitamin-J 175-group structure Table III.2. Energy group boundaries for GAM-II 100-group structure...37 Table III.3. Energy group boundaries for TART 175-group structure...38 Table IV.1. Distances (radii) from release point considered in the offsite dose library. Also radial intervals for ACAB calculations of collective dose, early fatalities, and cancer fatalities, are listed...56 Table V.1. Type of tables that are output by ACAB...68 Table VI.1. Example ACAB output. Isotopic masses Table VI.2. Example ACAB output. Radionuclide activities Table VI.3. Example ACAB output. Decay heat Table VI.4. Example ACAB output. Contact γ-ray dose rate III

8 Table VI.5. Example ACAB output. Contact Bremsstrahlung dose rate Table VI.6. Example ACAB output. Calculated γ-ray spectrum Table VI.7. Annual number of D-T experiments in NIF Table VI.8. Assumed D-T shots in the 67-pulse series for calculation purposes Table VI.9. Time steps for cooling between shots Table VI.10. Description of the 67-shots series IV

9 LIST OF FIGURES Figure I.1. Relative locations of products from the main nuclear reactions, with exception of fission, that are considered by ACAB....7 Figure III.1. COLLAPS flowchart Figure III.2. PROCDECAY flowchart Figure IV.1. ACAB flowchart for inventory calculations...42 Figure IV.2. ACAB flowchart for inventory and response function calculations...43 Figure V.1. Definition of the concept of "unit of time sets"...86 Figure VI.1. Proton and neutron flux spectrum computed by PHITS code Figure VI.2. Yield distribution computed by PHITS code V

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11 I. Major features of ACAB Methodology The ACAB code is a computer program designed to perform activation and transmutation calculations for nuclear applications. The main computational algorithm is based on that of the ORIGEN [Croff, 1980] code, and the program structure is based on that of the ACFA [Brockmann et al., 1983] code. ACAB is able to perform space-dependent inventory calculations allowing for a very flexible geometry and neutron flux description. The code solves the general nuclear transmutation chains for multidimensional neutron flux distributions. One- and two-dimensional multigroup neutron fluxes generated by discrete ordinates transport codes can be used. In addition, ACAB can use threedimensional neutron fluxes generated by Monte Carlo neutron transport codes allowing inventory calculations to be performed for complex geometries. The multigroup neutron fluxes may be given in an arbitrary group structure. ACAB considers decay transitions that proceed from the ground, first, and second isomeric states. All the neutron reactions that may occur in the different components of a nuclear facility are treated in the code. Each of the neutron reactions may proceed from a target atom in the ground, first or second isomeric state and result in a product that is in the ground, first or second isomeric state. The previous ACAB version [Sanz, 2000] could deal with all the reactions occurring at energies ranging from the thermal region to 20 MeV. To predict the transmutation calculations with neutron energies above 20 MeV (e.g. IFMIF), the ACAB code has been updated [Cabellos et al., 2007a]. Most of the applications of ACAB have addressed so far neutron activation problems for neutron scenarios corresponding to different kind of nuclear systems. For all the elements (including actinides), all the nuclear processes (including fission) and all the corresponding reaction products (including fission products) are considered in the inventory calculations. In dealing with fissionable nuclides, the associated fission yields included in the basic cross section library are used. Explicit information for independent yields coming from 19 fissionable nuclides is currently available [JEF/Report-21, 2006]. Fission yields for around 1696 nuclides can be managed. In Figure I.1 we show the relative locations of products from the main nuclear neutron induced reactions, with exception of fission, that are considered by ACAB. ACAB s primary result is isotopic concentrations as a function of time for each spatial interval and/or zone defined in the system. From the isotopic concentrations, ACAB is able to generate radionuclide activities, afterheat (total 1

12 and contributions from the different types of radiation), decay gamma spectra, contact dose rates, waste disposal ratings, offsite doses to the most exposed individual, as well as collective doses and associated consequences, radiotoxicity (committed effective dose equivalent by inhalation and ingestion) and neutron emission. Other quantities that depend upon isotopic concentrations and/or radionuclide activity can easily be added to ACAB. The subject of damage/transmutation calculations has been covered in this version. In the primary damage assessment of irradiated materials we have to predict displacements per atom (dpa) and gas production rates during the irradiation time. These quantities are needed for qualifying the material behaviour of some candidate structural materials for Magnetic and Inertial Fusion Energy. ACAB predicts the H- and He- production by nuclear reactions (n,xh) or (n,xhe) on all nuclei. In addition, ACAB provides the generation/depletion of transmutants and the dpa rates. Therefore, ACAB can predict the evolution of the dpa magnitude during the irradiation time. In order to predict the number of dpas, a multigroup damage library is required to be collapsed with the neutron flux spectra. In addition to the calculational facilities, ACAB also performs analysis of the activation results. Critical radionuclides are identified and pathways contributing to their production are evaluated. We have developed a methodology to compute uncertainties on inventory calculations. A computational method has been implemented in ACAB to assess the impact of activation cross sections uncertainties on inventory-related quantities. The method is based on the application of the Monte Carlo technique, and allows dealing efficiently with the synergic/global effect of the uncertainties of the total set of cross sections to obtain the overall uncertainty on the radiological calculations. This uncertainty analyses approach complements a former one based on the first order Taylor series [Sanz et al., 1996] [Sanz et al., 1998a]. This one was found it very practical in obtaining uncertainty indices on the production of nuclides associated to each of the reaction cross sections, ant to rank the cross sections introducing the largest uncertainties in their production, yet missing to deal with overall uncertainty provided by the Monte Carlo-based approach. The two proposed methods are complementary and allow dealing with the uncertainty problem in a comprehensive way. Monte Carlo calculations will provide the overall uncertainty on the radiological calculations, while the first order Taylor approach will allow analyzing the Monte Carlo results, given the contribution to the total uncertainty in the activation response coming from the uncertainty in each cross section. 2

13 ACAB is also able to deal with induced activation due to an external source of charged particles and/or photons. ACAB calculates the corresponding transition matrix coefficients for induced charged particle/photon reactions by using adequated charged particle/photon cross section libraries. Applications of ACAB to photon activation problems have not been done yet. For applications to charged particle-induced reactions, the available activation cros sections have been used (mainly for p and D, see Table I.1); for the others (T, He 3, ) we have used activation libraries generated from dedicated nuclear model codes (see Table I.1). Some of the possible reactions with charged particles are shown in Fig. I.1 to compare relative location of products generated from neutron and some different kind of charged particle reactions. The sequential charged particle (SCP) process is implemented in ACAB to predict the neutron source from alfa reactions. The complete computer module for dealing with SCP reactions, not only for alfa, in order to compute the inventory from other light charged particles (He 3, p, D, T), will be implemented in the next version. Applications ACAB has the ability to simulate realistic operational scenarios of very different nuclear systems: inertial fusion, magnetic fusion, accelerator driven systems, fission reactors, In particular, ACAB provides an accurate and efficient modeling of the pulsed schedule for inertial fusion experimental facilities, such as the National Ignition Facility, NIF [Latkowski, 1999] [Latkowski and Sanz, 1999] [Sanz et al., 2001] [Sanz et al., 2002]. Complex irradiation/cooling history can be easily represented by a series of irradiation/cooling periods, defined as a unit, which can be repeated a specified number of times and followed by distinct irradiation and cooling periods. These features together with the restart options lately included in the code allow modeling of any arbitrary irradiation/cooling scenario. The flexibility in modeling complicated irradiation/cooling operational scenarios has allowed ACAB to analyze if a continuous-pulsed (CP) approach could be and accurate and practical method for calculating neutron-activation under the pulsed irradiation regimes of Inertial Fusion Energy (IFE) power plants [Sanz et al., 1999a]. This model assumes a continuous irradiation period followed by a series of pulses prior to shutdown, and the total fluence and operation time is conserved. We have investigated the number of pulses needed to predict accurately the activation for some components of the IFE HYLIFE-II reactor. The CP method has been found it very valuable, since only a few number of pulsed are needed to obtain an acceptable solution. 3

14 Some capabilities have been included allowing for instantaneous feed of materials into a system. As a result, ACAB is able to deal with scenarios in which materials are intermittently irradiated, and material is fed instantaneously and/or continuously (feature already included in a former version) into the system. These capabilities have been shown to be very useful to study the activation of target debris in inertial experimental facilities similar to NIF, since the problem can be accurately modeled under a pulsed irradiation and instantaneous feed scenario [Sanz et al., 1999b]. The problem of activation of target materials has been explored. In IFE, in addition to pulsed activation of the materials of the different components of the fusion facility, it is also necessary to model the activation of target debris. The importance of this radioactivity source, especially for hohlraum targets, is an important question to be adressed. We have proceed in calculations aimed firstly to NIF-type experimental facilities [Sanz et al., 1999b] and to HYLIFE-II-type IFE power plants [Balmisa et al., 1998, Latkowski et al., 2001]. The capabilities needed for a complete and accurate modeling of these kinds of scenarios -with arbitrary irradiation/cooling history and feed/extraction processes is developed and implemented in the ACAB code. The performance capability of ACAB has been benchmarked against other codes as well as against experiment [Cheng et al., 1993] [Belian et al., 1998]. Regarding code comparison exercises, it is worth mentioning the International Atomic Energy Agency (IAEA) Second International Activation Calculation Benchmark Comparison Study [Cheng et al., 1993]. The IAEA Benchmark was based on four criteria: (a) ability to read standard libraries (cross sections GAM-II or Vitamin-J group structures); (b) accurate (to within about 5%) calculation of quantities of isotopes in multistep pathways; (c) ability to calculate light nuclide (H and He isotopes) production; and (d) ability to treat isomeric states present in the libraries. Out of eleven worldwide codes participants of the study, ACAB was one of the only two codes that was able to satisfy all four criteria, and was assessed as suitable and satisfactory for detailed fusion calculations. Regarding experiment validation, the code has been benchmarked against experiment using the Rotating Neutron Source (RTNS) for concrete activation studies, with excellent results [Belian et al., 1998]. The potential of ACAB for the IFE applications has been proved in a significant number of studies. It can be mentioned (in addition to those carried out by different members of the Instituto de Fusion Nuclear), the applications performed by the Department of Nuclear Engineering at the University of California, Berkeley [Balmisa et al., 1998] ; the activation assessments of the conceptual reactor KOYO, proposed by the Institute of Laser Engineering (ILE) at the University of Osaka [Nakai et al., 1996] [Perlado et al., 1996] ; and particularly, the applications for IFE [Latkowski et al., 1999a, 1999b] [Reyes et al., 1999] and NIF [Latkowski, 1999] [Latkowski and Sanz, 1999] 4

15 performed by Lawrence Livermore National Laboratory. This Laboratory partially supported the maintenance and development of ACAB during Currently, in the frame of the project HiPER: European High Power laser Energy Research Facility, ACAB is being used as reference code for activation analysis in the chamber design. The capability of ACAB to compute uncertainties on activation calculations due to cross section uncertainties has been applied to the activation assessment of the NIF test facility [Sanz et al., 2003] and different IFE power plants (thick-liquid-wall chamber and dry wall chamber) [Sanz et al., 1996] [Cabellos et al., 2003; 2006b] [García-Herranz et al., 2006] [Reyes et al., 2006a]. In particular, a comprehensive waste management assessment of all the different types of steels as potential structural material for the HYLIFE-II concept has been perfomed [Sanz et al., 2005] [Cabellos et al., 2006a]. A compilation of the main safety and environmental analysis performed for fusion facilities can be found in references [Latkowski et al., 2002; 2003], [Sanz et al., 2006]. Although we have mainly focused to applications in IFE concepts, some applications have been performed in MFE concepts as well [Cabellos et al., 2006c], [Cabellos et al., 2008]. Even if ACAB was primarily applied to fusion reactors, it can also be succesfully applied to very different nuclear systems. Our computational tool has demonstrated to deal with the activation/transmutation issues of the intense neutron source facility IFMIF (International Fusion Material Irradiation Facility), where the numerous reaction channels for neutron energies over 20 MeV have to be handle [Cabellos et al., 2007b] [Rapisarda et al., 2008]. More recently, ACAB is being used to explore the problem of activation of materials in different accelerator projects. One of the most critical challenges in the design of the Rare Isotope Accelerator (RIA), involving heavy element ion beams, is the beam dump design. The problem of activation of beam dump components has been assessed with the ACAB code [Reyes et al., 2006b]. Activation evaluations are currently in progress in the Engineering Validation and Engineering Design Activities (EVEDA) phase of the IFMIF project. It should result in an accelerator prototype for which the analysis of the dose rates evolution during the beam-off phase is a necessary task for radioprotection and maintenance feasibility purposes. In the frame of this project some efforts has been done to predict residual dose rates associated to the radioactive inventory and the corresponding decay photon source in accelerating elements [Sanz et al., 2008, Garcia et al., 2008] and beam dump [Sanz et al., 2009], [Brañas et al., 2008]. Also, in the current definition phase of the project TECHNOFUSION: The Spanish National Centre for Fusion Technologies, the ACAB code is being used addressing the activation problems associated to the use of the set of three accelerators proposed to simulate neutron irradiation damage 5

16 ACAB has been successfully applied to compute the transmutation/evolution of the isotopic inventory and associated fuel cycle parameters in different Accelerator Driven System (ADS) transmuters [Cabellos et al., 2005] [Sanz et al., 2007b]. The applicability of the code to deal with ADS systems has extensively been proved within the frame of the EU Integrated Project EUROTRANS [EUROTRANS, 2005]. The performance of different methodologies to address uncertainty estimations was also analysed in detail in the frame of this project [Sanz et al., 2006, 2007a][García-Herranz et al., 2008]. The potential of ACAB for fission reactor applications has been proved in different comparison exercises. To deal with burnup problems, ACAB was coupled to a Monte Carlo neutron transport code. The full system was succesfully applied to: a UO2 pin-cell benchmark [García-Herranz et al., 2005], an ATRIUM-10XP design BWR fuel assembly [Ortego et al., 2006], a high temperature gas-cooled reactor plutonium burnup benchmark [García-Herranz et al., 2008], demonstrating to be reliable to compute accurate isotopic inventory. Table I.1 gives a description of the major new capabilities included in the present version of ACAB, which enhance significantly the former versions (ACAB -1.0 [Sanz et al., 1992], ACAB -2.0 [Sanz et al., 1995] ACAB -3.0 [Sanz et al., 1998], ACAB -4.0[Sanz, 1999] and ACAB -5.0 [Sanz et al., 2000] ). The code is written in standard FORTRAN 77, and runs on Unix workstations, PC Windows and linux-based PC. This updated ACAB version is fully portable to all computers. 6

17 Z+2 3 ( He,n) ( α,n) Z+1 (p,n) (d,2n) (d,n) (t,2n) (t,n) Atomic Number Z Z-1 (n,4n) (n,3n) (n,nt) (n,2n) (n,2np) (n,t) (n,nd) Original Nucleus (n,n) (n,d) (n,np) (n, γ) (n,p) Z-2 (n,2n α ) (n,n α) (n, α) 3 3 (n, He) (n,n He) (n,2p) Z-3 Z-4 (n,n2 α ) (n,2 α) N-4 N-3 N-2 N-1 N N+1 Neutron Number Figure I.1. Relative locations of products from the main neutron nuclear reactions, with exception of fission, that are considered by ACAB. Also relative locations of products from some charged-particle induced reactions are shown as an example. Note: ACAB considers all the neutron reaction types included in the used activation neutron cross-section library. The target can be an atom in the ground, first or second isomeric state. Neutron reactions may result in a product that is in the ground, first or second isomeric state. 7

18 Table I.1. Capabilities of ACAB included in the current version 1.- Geometry and flux description - Space-dependent inventory calculations for multigroup scalar neutron fluxes are possible. - Induced activation due to an external source of charged particles and/or photons is also possible. - Coupling to 1 and 2 D discrete ordinates transport codes is possible. - Coupling to Monte Carlo transport code such as TART and MCNP is possible. The TARTREAD [Latkowski, 1995] code has been designed to read a TART [Cullen, 1998] output and create usable ACAB input files. The coupling MCNP-ACAB has also been perfomed [García-Herranz, 2008a]. 2.- Operational scenario Irradiation/cooling history - Irradiation period with constant flux (steady-state operation) and subsequent cooling period is allowed. - Modeling of pulsed irradiation is possible. A series of pulses with different on and off time (that is, with different width and dwell time), and flux level can be accommodated. - A series of pulses can be repeated a specified number of times and may be followed by an additional irradiation/cooling period. - The above-mentioned capabilities together with the restart options, allow modeling of any arbitrary irradiation/cooling scenario, and easy definition of complicated irradiation/cooling histories Feed of materials into the system - Continuous feed in specified intervals within the total operational period. - Instantaneous feed at specified times within the total operational period. Consequently, we can deal with scenarios in which materials are intermittently irradiated, and material is fed continuously and/or instantaneously into the system. 8

19 3.- Nuclear processes - Basically all the decay transitions are considered. Parents and daughters can be in ground, first, and second isomeric states. - All the kinematically allowed neutron, deuteron and proton reactions included in the corresponding cross-section libraries are considered for each target isotope. Target and daughter can be in ground, first, and second isomeric states. - Generation of fission products. 4.- Decay photons - Photons produced from ground state, first and second isomers. 5.- Basic nuclear data libraries - Neutron activation cross section library from EAF_N Charged-particles (D and p) activation cross section libraries from EAF_D and EAF_P Other charged-particles activation libraries (T, He 3, He 4 ) from dedicated nuclear model codes (TALYS 1.0 [Koning et al., 2008] ). - Decay data library from EAF_DEC Fission yield data from EAF_N_FIS Cross-section uncertainty data library from EAF_UN Processing/collapsing of cross section libraries (COLLAPS code) - The COLLAPS code, a module of the ACAB package, can condense multigroup cross section libraries down to a single group. - The cross section libraries to be collapsed must be in EAF (European Activation File) format. - The program is able to handle cross section libraries in the standard GAM-II(100), Vitamin-J(175), Vitamin-J+(211), and TART-175 and TART-566 group structures. - The neutron flux used to produce the 1-group energy-averaged cross sections may be input in an arbitrary group structure. - COLLAPS produces weighted fission product yield and weighted fission yield cross section libraries. - The fission yield data library to be collapsed must be in ENDF-6 format (this format is that of the used fission yield libraries). - COLLAPS produces weigthed cross section uncertainty data. - COLLAPS produces weigthed cross section damage data. - In general, COLLAPS can create a pseudo cross section library according with the weighting function provided by the user. 9

20 7.- Contact gamma dose rate and other inventory-related quantities - Dose rate from a semi-infinite slab of material may be calculated. - Dose rate from a thin layer of material may be calculated. - Analyses of dose rate production have been added including highenergy Bremsstrahlung contributions. - Afterheat: total and contributions from the different types of radiation. - Waste disposal ratings. - Commitment effective dose equivalent by ingestion and inhalation. - Neutron emission by (alpha,n) and spontaneous fission. - DPA rate. 8.- Offsite doses and consequences - Offsite dose to the red bone marrow, lung and gastrointestinal tract of the most exposed individual. Early fatalities. - Effective dose equivalent to the most exposed individual. Collective dose and cancer fatalities in different release, exposure, and relocation scenarios. 9.- Pathway analysis (CHAINS code) - The CHAINS code, other module of the ACAB package, performs computational pathway analyses. - Pathways for the formation of a particular nuclide that require up to a specified number of steps are ranked according to their estimated importance to the total production of the nuclide. - Pathways that result in the formation of a particular nuclide with a maximum number of steps in the chain (no initial nuclide is specified). - Pathways starting from a specified parent nuclide that result in a specified daughter nuclide. - All the nuclear processes implemented in ACAB are considered Uncertainties on activation calculations - Monte Carlo uncertainty analysis. - Uncertainty analysis based on sensitivity analysis is no included in this version Computer platforms - ACAB is written in standard FORTRAN 77, and runs on Unix workstations, PC Windows and linux-based PC. - This uptaded ACAB version is fully portable to all computers. 10

21 II. Selection of nuclear data libraries The nuclear data basic libraries required as starting point to prepare those directly used by ACAB for inventory calculations are the following: A multigroup activation neutron cross-section basic library, obtained from FENDL/A-2.0 [Paschenko et al., 1997], EAF_XS-2005 [Forrest et al., 2004], EAF_N_XS-2007 [Forrest et al., 2007], For activation calculations with other particles (proton, deuteron, photon), the required library would be the corresponding multigroup particle-induced cross-section library (e.g. obtained from EAF_P_XS-2007 [Forrest, 2007b] for protons, EAF_D_XS_2007 [Forrest, 2007b] for deuterons, ). A decay data basic library, such as FENDL/D-2.0 [Forrest, 1997], EAF_DEC [Forrest, 2004b], EAF_DEC-2007 [Forrest, 2007c], A fission yield basic library, such as that of JEF-2.2 [JEF/DOC-538, 1995], JEFF- 3.1 [JEFF/Report-21,2006], EAF_N_FIS_20070 [Forrest, 2007a], A cross-section uncertainty data basic library, such as FENDL UN/A- 2.0 [Paschenko et al., 1997] [Kopecky et al., 1994] [Kopecky and Nierop, 1995], EAF_UN-2005 [Forrest et al., 2004], EAF_N_UN-2007 [Forrest et al., 2007], In the problems presented in this user manual, the libraries selected as starting point are: EAF_N_GXS_175_FLT-2007 (or EAF_N_GXS_211_FLT-2007) is selected as the activation neutron cross-section basic library (XSBL.dat). For proton-induced calculations, EAF_PXS_211_FLP-2007 is the basic cross section library chosen. EAF_DEC-2007 is selected as the decay data basic library (DBL.dat). EAF_N_FIS_2007 is selected as the fission yield data basic library (FYBL.dat). EAF_UN-2007 is selected as the cross-section uncertainty data basic library (UNBL.dat). On the other hand, the use of FENDL-2.0 nuclear data libraries can also be found in some examples included in this user manual in order to clarify some input descriptions. In the rest of this section, the main characteristics of the used libraries are described. 11

22 II.1. Nuclear data libraries selected as starting point The EAF-2007 data library [Forrest, 2007a] was produced by NRG Petten and the UKAEA within the European Activation File project, and released in The term EAF originally described only the neutron-induced cross-section library, but is now used to cover all the nuclear data libraries required for inventory calculations. A.- Activation neutron cross-section basic library: EAF_N_GXS-2007 The selected multigroup activation cross section library is one of the groupwise libraries available in EAF These multigroup files are obtained from the point-wise cross section library EAF_N_XS-2007, in one of seven group-structures: that of GAM-2 (100 groups), VITAMIN-J (175 groups), WIMS (69 groups), XMAS (172 groups), VITAMIN-J+ (211 groups), TRIPOLI (315 groups) and TRIPOLI+ (351 groups), with different choices of flux weighting spectra. For the examples included in this user manual, two different group-wise libraries have been selected: one in the VITAMIN-J(175) group structure (EAF_N_GXS_175_FLT-2007) and the other in the VITAMIN-J+(211) group structure (EAF_N_GXS_211_FLT-2007); both of them processed with a flat weight function. The point-wise library EAF_N_XS-2007 contains data on 65,565 cross sections on 816 targets in a modified ENDF/B format. The energy range 10-5 ev 60 MeV is covered. All nuclides with a half-life of greater than 6 hours have cross section data, but in addition some short-lived nuclides are also treated as targets. The cross sections represent targets that are infinitely dilute, no self-shielding is included and the temperature for Doppler broadening is 300K. The 86 different reaction types included in the library are given in Table II.1, with the corresponding code in EAF-format. Taking into account the different possible transitions from ground, 1 st and 2 nd isomeric states, a total number of 250 types of neutron reactions are included. The sources for the cross section data of these reactions are listed in Table II.2. Table II.1. Reaction types included in EAF-2007 ICODE REACTION ICODE REACTION ICODE REACTION 40 (N,N) 1090 (N,3A) 1730 (N,4NT) 110 (N,2ND) 1110 (N,2P) 1740 (N,5NT) 160 (N,2N) 1120 (N,PA) 1750 (N,6NT) 170 (N,3N) 1130 (N,T2A) 1760 (N,2NH) 180 (N,F) 1140 (N,D2A) 1770 (N,3NH) 12

23 220 (N,NA) 1150 (N,PD) 1780 (N,4NH) 230 (N,N3A) 1160 (N,PT) 1790 (N,3N2P) 240 (N,2NA) 1170 (N,DA) 1800 (N,3N2A) 250 (N,3NA) 1520 (N,5N) 1810 (N,3NPA) 280 (N,NP) 1530 (N,6N) 1820 (N,DT) 290 (N,N2A) 1540 (N,2NT) 1830 (N,NPD) 300 (N,2N2A) 1550 (N,TA) 1840 (N,NPT) 320 (N,ND) 1560 (N,4NP) 1850 (N,NDT) 330 (N,NT) 1570 (N,3ND) 1860 (N,NPH) 340 (N,NH) 1580 (N,NDA) 1870 (N,NDH) 350 (N,ND2A) 1590 (N,2NPA) 1880 (N,NTH) 360 (N,NT2A) 1600 (N,7N) 1890 (N,NTA) 370 (N,4N) 1610 (N,8N) 1900 (N,2N2P) 410 (N,2NP) 1620 (N,5NP) 1910 (N,PH) 420 (N,3NP) 1630 (N,6NP) 1920 (N,DH) 440 (N,N2P) 1640 (N,7NP) 1930 (N,HA) 450 (N,NPA) 1650 (N,4NA) 1940 (N,4N2P) 1020 (N,G) 1660 (N,5NA) 1950 (N,4N2A) 1030 (N,P) 1670 (N,6NA) 1960 (N,4NPA) 1040 (N,D) 1680 (N,7NA) 1970 (N,3P) 1050 (N,T) 1690 (N,4ND) 1980 (N,N3P) 1060 (N,H) 1700 (N,5ND) 1990 (N,3N2PA) 1070 (N,A) 1710 (N,6ND) 2000 (N,5N2P) 1080 (N,2A) 1720 (N,3NT) Table II.2. Sources for the cross section data included in EAF-2007 Data source Number of reactions Data source Number of reactions ACTL 2 JAERI(MDF) 12 ADL JEF ADL-3/I 5 JEF-2.2(MDF) 6 BRC 1 JEFF BROND JENDL CRP 8 JENDL EFF JENDL-3.2/A 55 ENDF/B-VI 26 JENDL-3.2/A/I 1 ENDF/B-VI(MDF) 4 JENDL ENDF/B-VI.7 11 JENDL-99D 1 ENDF/B-VI.8 12 KOPECKY ENDF/B-VII.0 3 LANL 4 ENDF/B-VII.2 14 LANL(HERMAN) 7 ENEA(MENGONI) 4 LANL ESTIMATE 10 MASGAM 401 EXIFON 1 MASLOV 4 FEI 5 MENDL-2 1 FENDL/A-1 10 NGAMMA 21 FISPRO 9 RRDF

24 HEPRL 10 SIG-ECN 1 IEAF SIGECN-MASGAM 64 IRDF TALYS IRDF TALYS-5a 557 IRDF-P 4 TALYS IRK 32 TALYS-6a JAERI 3 WIND 1 Total B.- Decay data basic library: EAF_DEC-2007 In the selection of the decay data basic library, the criteria to follow is to take the one most compatible with the selected activation library (the EAF-2007 in our case). Consequently, the EAF-2007 decay data library (EAF_DEC-2007) is the logical choice. The two main compatibility requirements between the activation and the decay library are: i) all nuclides referred to in the activation library and fission yield library must have data in the decay library, and ii) the identification of isomeric states used in both libraries should be identical. EAF_DEC-2007 contains decay data information for 2231 nuclides, 1754 in ground state, and 439 and 38 in 1 st and 2 nd isomeric states respectively. It is based primarily on the JEFF-3.1 radioactive decay data library, with additional evaluations. It includes data on half-lives, decay modes and decay energies. Isotopes with multiple particles emission are included: β - +α, β - +n, β - +n+n, CE+p, CE+α, IT+α. The basic library contains data in ENDF/B-6 format, and need to be processed before it can be used by ACAB. The utility program PROCDECAY reads decay data libraries in ENDF/B-6 for producing different files with the decay data in the format required by ACAB (see Section IV). C.- Fission yield data basic library: EAF_N_FIS-2007 This library is taken completely from the JEFF-3.1 fission yield library [JEFF/Report-21,2006]. It contains the energy-dependent fission product yield data for three different incident neutron energies: ev, 0.4 MeV and 14 MeV. Information is given for the independent fission yields coming from 19 fissionable nuclides (only 19 of the 102 nuclides in EAF_N_XS which have fission cross sections, have any fission yield data in JEFF-3.1 at relevant energies). The fission yield from each of the fissionable nuclides is given for around 1696 nuclides. 14

25 The fissionable nuclides with fission product yield data are listed in Table II.3. It can be seen that for some of these fissionable nuclides there are missing points, that is, yield data are not given for the three energy points, yet the fission cross section is not negligible in some cases for a neutron having the energy of a missing point. The format of the library is ENDF-6, and should be processed by the COLLAPS code (see Section III) for producing the weighted fission yields libraries to be read directly by ACAB. Table II.3. Fissionable nuclides with fission product yield data in EAF_N_FIS Incident neutron energies (ev) Fissionable 2.53 x x x 10 6 Th Y Y U-233 Y Y Y U Y -- U-235 Y Y Y U Y -- U Y Y Np-237 Y Y -- Np-238 Y Y -- Pu-238 Y Y -- Pu-239 Y Y -- Pu Y -- Pu-241 Y Y -- Pu Y -- Am-241 Y Y -- Am-242m Y Y -- Am-243 Y Y -- Cm-243 Y Y -- Cm-244 Y Y -- Cm-245 Y Y -- D.- Cross section uncertainty data basic library: EAF_UN-2007 EAF_UN-2007 is selected as the cross-section uncertainty data basic library. EAF_UN-2007 contains uncertainty data for all cross sections included in the corresponding standard cross section library (EAF_N_XS-2007). The data in the library, in modified ENDF/B-6 format, are uncertainty values in a two- to four-energy group structure (up to 60 MeV). For threshold reactions, the uncertainty data are in a two-group format, from the threshold to 20 15

26 MeV and from 20 to 60 MeV. A four group format is adopted for the non-threshold reactions: from 10-5 ev to EV (the end of the 1/v region), EV to EH (the end of the resonance region), EH to 20 MeV and 20 to 60 MeV. Note that the energy group boundaries can be different for each reaction and isotope. The uncertainty values actually stored in the file are 2 j,eaf (being j the energy group) where j,eaf refers to the relative error (uncertainty) in the standard cross section σ 0 contained in the corresponding activation file. It is assumed that cross sections within the same energy group are fully correlated, whereas crosssection values in different groups are assumed to be statistically independent. We assume the uncertainty values in the library, EAF, to be three times the experimental relative error, that is, j, EAF = 3 j, EXP (j=1,energy group number) in order to represent a 99.73% confidence level. This assumption comes from the fact that in the EAF_UN-2007 library, it is considered that the best estimate of a cross section uncertainty is: σ 0 σ σ 0 f f where f is an error factor defined as f = 1 + EAF, being EAF the relative error in the cross section σ. Then, 1 σ σ f lnf ln lnf f σ σ For small values of x, ln x 1 Let us consider ln σ σ 0 0 σ x ( f 1) ln f 1 EAF ln EAF σ 0 σ 0 as a random variable normally distributed, being EXP the standard deviation of the normal distribution. Then, the value of the variable would be in the interval ( 3 EXP, 3 EXP ) with a 99.73% confidence level. On the σ other hand, since the best estimate of the cross section is ln, we σ can identify EAF as approximately three times the experimental relative error. To address the uncertainty problem in a comprehensive way, we have used the fact that when evaluating cross sections, the quantity log(σexp/σcal) was approximately normally distributed. Consequently, we assume that for any given cross section σ, we can define the random variable ln(σ/σ0) that follows a normal distribution with mean zero and variance 2 EXP. The value σ0 is the standard cross section from the corresponding activation cross section file, and 2 EXP = 2 EAF/9. 0 EAF 0 σ EAF. 16

27 The format of the uncertainty library is basically ENDF-6, but presents some deviations regarding to material and reaction nomenclature. The library needs to be processed by the COLLAPS code (see Section III) for producing a consistent joint weighted cross-section and uncertainty data library to be read directly by ACAB. E.- Proton and Deuteron-induced cross section basic libraries: EAF_P_XS-2007 and EAF_D_XS-2007 The EAF-2007 data library was released in 2007 and contains libraries with cross section data for charged-particles induced reactions. EAF_P_XS-2007 is the point-wise proton-induced cross section library. The set of reactions in this library was determined by the data available in TALYS-6p. Data on 67,925 cross sections on 803 targets are held in a modified ENDF/B format. The energy range 10-5 ev 60 MeV is covered. The cross sections represent targets that are infinitely dilute, no self-shielding is included and the temperature for Doppler broadening is 300K. No associated uncertainty file is included. EAF_D_XS-2007 contains 66,864 reactions, mainly obtained from TALYS-6d, including 86 reaction types. In addition to the pointwise file, there is a single multigroup library in the VITAMIN-J+ (211-group) flat-weighting format. As with proton library, there is no uncertainty file. II.2. Other nuclear data basic libraries A.- Activation neutron cross section basic library FENDL/A-2.0 The FENDL/A-2.0 library is a neutron cross section data base produced within the IAEA FENDL project which has the goal of providing a comprehensive Fusion Evaluated Nuclear Data Library for predicting all nuclear processes in fusion devices. The FENDL/A-2.0 file contains data for all stable and unstable target nuclides with half-lives longer than ½ day. If a reaction produces isomers the cross section for the ground- and isomer-state are given separately. The FENDL/A-2.0 includes 739 target nuclides from H (A=1, Z=1) to Cm (A=248, Z=96) with 13,006 reactions, in the incident energy range up to 20 MeV. These reactions are significant in producing activation both at short and long cooling times. The reaction types and number of reactions for each type included in the library are given in Table II.4, and the sources for the cross section data of these reactions are listed in Table II.5. There are 21 different reaction types in FENDL/A-2.0, and all 17

28 kinematically allowed reactions below 20 MeV are specified for each target isotope. The FENDL/A-2.0 activation library can be considered as formed by two parts: i) a sublibrary of important reactions for fusion applications, and ii) a basic library which complements the important reaction sublibrary. The FENDL/A-2.0 Sublibrary of Important Reactions contains 398 reactions important for fusion reactor technology in general, although at first it was particularly aimed for activation studies within the ITER design. The sources for the cross section data of these reactions are given in Table II.6. In the FENDL/A-2.0 basic library all the cross-section data have been selected from the European Activation File version 4 (EAF-4.1) [Kopecky et Nierop, 1995]. Considering the two parts together, we have that in FENDL/A-2.0 the bulk of the data is EAF-4.1, with around 240 selections (see Table II.5) from ADL-3, JENDL/A-3.2, FENDL/A-1.1, ENDF/B-VI, IRDF-90.2, IRK and CRP. It has been emphasized [Paschenko et al., 1997] [Herman et Pashchenko, 1997] that the basic library contains evaluated neutron activation cross sections selected from existing activation data files. In assembling this library, no additional evaluation work was performed in order to improve evaluations; only existing evaluations were considered for inclusion. Therefore, in many cases the data given are theoretical estimates without or with limited experimental verification so that the data uncertainty may be significantly higher than for those evolved from careful evaluation and validation (such as the important reactions). Table II.4. Reaction types included in FENDL/A-2.0 [Paschenko et al., 1997] Reaction type N,2N N,3N N,4N N,G N,F N,N N,ND N,NP N,NA N,NT N,NH N,2P N,2A Number of Reactions

29 N,P 982 N,D 989 N,A 954 N,T 1010 N,H 914 N,2NA 2 N,2NP 1 N,N2A 1 Total Table II.5. Sources for the cross section data included in FENDL/A-2.0 Data Source Number of Reactions JEF EFF ENDF/B-VI 55 JENDL JENDL JENDL-3.2/A 80 JENDL-3.2/A/I 1 ACTL 2 LANL 9 ADL ADL-3/I 14 FISPRO 9 SIGECN-MASGAM 73 MASGAM 411 NGAMMA 1 THRES 753 EXIFON 249 SIG-ECN 1 IRDF ESTIMATE 22 CRP 9 FENDL/A-1 41 IRK 1 Total

30 Table II.6. Sources for the cross section data of the important reaction sublibrary of FENDL/A-2.0 [Paschenko et al., 1997] Data Source Number of Targets EAF ENDF/B-VI 1 JENDL/A ADL IRDF CRP (2) 8 FENDL/A IRK (1) 1 Total 398 (1) IRK stands for evaluation originating from the Institute für Radiumforschung und Kernphysik Vienna. (2) CRP is a product from Research Coordination Programme on the Activation Cross Sections for the Generation of Long-lived Radionuclides of IAEA [Pashchenko, 1995]. The rest of selections come from well-known and released libraries. B.- Decay data basic library FENDL/D-2.0 If the FENDL/A-2.0 has been chosen as activation cross section basic library, the FENDL decay data library (FENDL/D-2.0) will be the logical choice for the decay data basic library. In the selection of the decay data library for FENDL/D-2.0, the choice was to take directly the EAF-4.1 (EAF_DEC-4.1) decay library. With this choice, based on the fact that FENDL/A-2.0 is largely based on EAF-4.1 activation library, the two requirements above mentioned have been efficiently fulfilled. However, regarding the second requirement there are a few cases in which inconsistency of identification of isomeric states between the two libraries remain due to the inclusion of the important reactions subfile in FENDL/A-2.0. These inconsistencies, according to the FENDL/D-2.0 evaluators [Nakai et al., 1996], are on nuclides of very limited importance for fusion applications, and it was decided to let them remain. FENDL/D-2.0 contains decay properties (decay type, decay energy, half-life, photon yield) for 1875 nuclides and isomers, including ground, first and second isomeric states; and it is written in ENDF/B-VI format. 20

31 Table II.7. FENDL/D-2.0: Modes of decay and number of ground state and isomeric state daughters produced in each mode Mode of decay Ground state Daughters 1 st isomeric state 2 nd isomeric state β - decay β + decay Electron capture (ε) Isomeric transition (IT) alpha decay (α) 1 1 Neutron decay (n) Spontaneous fission 22 proton decay (p) 3 β - decay followed by n emission (β -, n) β - decay followed by α emission (β -,α) 6 4 C.- Fission yield data basic library JEF-2.2 This library contains the energy-dependent fission product yield data for three different incident neutron energies: ev, 0.4 MeV and 14 MeV. Information is given for the independent and cumulative yield coming from 19 fissionable nuclides. The fission yield from each of the fissionable nuclides is given for around 1450 nuclides. The fissionable nuclides with fission product yield data in JEF-2.2 are the same listed in Table II.3. The sources for those fission yield data are provided in Table II.8. 21

32 Table II.8. Sources for neutron-induced fission products yields in JEF-2.2 **************************************************************** JEF-2.2 TAPE 24 (FISSION YIELDS) **************************************************************** ******************************************************************************************************** DIST-JUN NEUTRON-INDUCED FISSION PRODUCT YIELDS ENDF-6 FORMAT ADJUSTED INDEPENDENT AND CUMULATIVE YIELD LIBRARIES TERNARY FISSION AND ISOMERIC SPLITTING INCLUDED DESCRIBED WITHIN REPORTS AEA-TRS-1015, 1018 AND 1019 THIS WORK WAS SPONSORED BY THE UKAEA, BNF PLC AND NUCLEAR ELECTRIC. THIS REMAINS THE JOINT PROPERTY OF THE SPONSORS BUT CAN BE DISTRIBUTED FREELY. NO LIABILITY CAN BE ACCEPTED BY THE SPONSORS FOR THE USE, OR MISUSE, OF THIS DATA. ******************************************************************************************************** 90-TH-232 WIN EVAL-JUN93 M.JAMES AND R.MILLS ----JEF-2.2 MATERIAL 9061 **************************************************************** 92-U -233 WIN EVAL-JUN93 M.JAMES AND R.MILLS ----JEF-2.2 MATERIAL 9234 **************************************************************** 92-U -234 WIN EVAL-JUN93 M.JAMES AND R.MILLS ----JEF-2.2 MATERIAL 9237 **************************************************************** 92-U -235 WIN EVAL-JUN93 M.JAMES AND R.MILLS ----JEF-2.2 MATERIAL 9240 **************************************************************** 92-U -236 WIN EVAL-JUN93 M.JAMES AND R.MILLS ----JEF-2.2 MATERIAL 9243 **************************************************************** 92-U -238 WIN EVAL-JUN93 M.JAMES AND R.MILLS ----JEF-2.2 MATERIAL 9249 **************************************************************** 93-NP-237 WIN EVAL-JUN93 M.JAMES AND R.MILLS ----JEF-2.2 MATERIAL 9346 **************************************************************** 93-NP-238 WIN EVAL-JUN93 M.JAMES AND R.MILLS ----JEF-2.2 MATERIAL 9349 **************************************************************** 94-PU-238 WIN EVAL-JUN93 M.JAMES AND R.MILLS ----JEF-2.2 MATERIAL