NEA-1856 VESTA 2.1&AURORA1.0.

VESTA 2.1.5 & AURORA 1.0.0

VESTA is a Monte Carlo depletion interface code that is currently under development at IRSN (France). From its inception, VESTA is intended to be a "generic" interface code so that it will ultimately be capable of using any Monte-Carlo code or depletion module and that can be completely tailored to the user's needs on practically all aspects of the code:

• the Monte Carlo transport module: by interfacing with various Monte Carlo codes;

• the depletion module: by interfacing with different point depletion codes but also with a built-in depletion module that allows a user to select specific reactions and/or decay modes to be used in the depletion calculation;

• the predictor-corrector algorithm: by offering  multiple algorithms like for instance a predictor only, the classic predictor-corrector or the midpoint approach that can be adjusted to the user's needs (by specifying the number of iterations, tolerances, etc.);

• the nuclear data: the code uses ENDF formatted data that can be changed easily when new data becomes available and a user can even pick data to be used for individual nuclides;

• the physics models: like for instance the treatment of the total recoverable energy per fission, etc.

For the current version, VESTA allows for the use of any version of MCNP(X) as the transport module and ORIGEN 2.2 or the built in PHOENIX module as the depletion module. A short overview of the main features of this version of the code is detailed below.

AURORA is a Java based data analysis tool for depletion codes (such as VESTA) that uses the new XML output structure defined for VESTA 2.1.

MAIN FEATURES OF VESTA:

Efficient reaction rate calculation:
It has been shown that the enormous CPU time consumption of continuous energy Monte-Carlo depletion codes is mainly due to the calculation of all the cross section values during the Monte-Carlo simulation for the reaction rate calculation. One way to reduce the calculation time without jeopardising the calculation's precision is to calculate the reaction rates after the Monte-Carlo simulation has finished using the multi-group binning approach. Only an ultra-fine multi-group spectrum (the default group structure consists of 43000 groups, but this can be changed by the user) has to be calculated by the Monte-Carlo code. The reaction rates are then determined by collapsing multi-group cross-sections to a single group using the calculated spectrum. Due to the very nature of the ultra-fine spectrum, this method takes into account the self-shielding effects. The calculation time of every depletion step (regardless of the number of reaction rates required) is almost reduced to that of the basic Monte-Carlo simulation. The reduction in calculation time is quite significant (in practical applications, a speed-up of at least a factor 5 to 10 has been observed).
In accordance with the generic nature of VESTA, a user can also choose to use the traditional method of calculating the reaction rates using the Monte Carlo code directly. This gives the user an easy way to test the results obtained with the multi-group binning approach.

Complete Nuclear Data Consistency:
Although the various reaction cross sections form the bulk of the data needed to perform a depletion calculation, the importance of isomeric production branching ratio data, direct fission yield data or radio-active decay data cannot be ignored either. All of these data can be found in ENDF files, in one form or another. Reading the data directly from ENDF files will provide us with a consistent set of data, for both the depletion and transport module within VESTA. This will also allow us to quickly change our data when new evaluations become available, making the code very flexible in its nuclear data use. The current version of VESTA is already capable of using ENDF formatted fission yield and decay data.

Modeling Irradiation Conditions:
VESTA uses the relative flux distribution as calculated by the Monte Carlo code to calculate the absolute flux levels in the case of constant flux irradiation. When using constant power irradiation, VESTA distributes the power production over the different materials using a relative power distribution, determined by every material's specific normalization power (which is in turn determined by the total recoverable energy from fission).
VESTA has also the capability of performing material changes during irradiation. A user can change the density and/or temperature of any material that is not being burned (to for instance simulate heating effects of water, etc). A user can also change the temperature of a burnable material or even replace it with another burnable material (which can be a new material to simulate core reshuffling and reloading). Burnable materials that are being taken out of the model will, by default, undergo decay so that these materials can be used again at a later point in the irradiation history. Geometry changes (by using surface transformations) for instance for the simulation of control rod movement during the irradiation cycle has also been implemented.

Predictor-corrector Methods:
To provide the user with a flexible tool, various predictor-corrector methodologies have been implemented in VESTA. Currently VESTA allows for the use of a predictor only step (which is acceptable when the time step is relatively small), a predictor-corrector time step and the middle-step method (using the reactor spectrum at the middle of the time interval to perform the depletion calculation over the time step).

MAIN FEATURES OF AURORA:

The basic output produced by any depletion code including VESTA consists of the composition of the various materials as a function of time, the cross section data applied to these materials as a function of time and the power and flux distributions to which the materials were subjected. In particular, the output from VESTA can basically be split up into the following categories:

• output related to the materials themselves: the atomic density for every isotope (in atoms/barn/cm) and the accumulated burn up (this can also be derived from the data but it is given because it is convenient);

• output related to the irradiation conditions of those materials, consisting of global data such as which materials are being used in which zone at every point in time, which temperature is used in which zone at every point in time and the volume of the depletion zones;

• output related to data required by the depletion module: the flux and power distribution (the points in time at which these are given are not necessarily the same as those used for the cross section data and composition data), the single group cross section data used to model the evolution of every material as a function of time and the fission Q value (the total recoverable energy release per fission) for a fissile isotope;

• general data independent of either the depletion zones and/or the burnable materials like decay data (including decay modes, half life, energy per decay event, etc.), neutron induced fission yield data and atomic mass data.

These data represent the basic output from which other data can be derived. As such, it was decided early on in the development of VESTA to not add various output options for the user which would unnecessarily overcomplicate both the code itself and its input files, but also increase the overall size of the output files. In addition, if a user would need additional derived data from a calculation that was run earlier, it would require the calculation to run again which is not really necessary because the basic data needed to derive the additional data is already available. The dissociation of the calculation from the data analysis now allows a user to run high precision reference calculations and analyse the results whenever the need arises. This is of interest for full 3D core calculations for fast reactors which can take a long time to complete.

The task of extracting and visualising the basic results, but also the calculation of physical quantities or other data that can be derived from the basic output provided by VESTA will be the task of the AURORA depletion analysis tool. The following is a (non exhaustive) list of the tasks to be performed by AURORA:

• unit conversion of any basic output data or derived data, for instance to obtain compositions as g/cm3, g/tHM, etc. instead of the standard atoms/barn/cm; quantity (such as activity, decay heat, etc.);

• calculate the physical quantities that can be derived from this data of interest to a user such as activity (multiply the composition of a nuclide by the decay constant) or decay heat (multiply the activity of a nuclide by the average decay energy per decay event);

• calculate material averaged quantities and system averaged quantities based on the physical quantities for individual nuclides described above;

• determine the importance of a set of nuclides (for a given point in time) based on a given physical quantity.

The current version of AURORA allows for the extraction and calculation of the following physical quantities and units:

• composition : atoms/barn/cm (default), atoms/cm3, atoms/tHM, atoms, g/cm3, g/l, g, g/tHM

• cross sections : barn (default), cm2

• reaction rate: 1/s (default), 1/s/cm3

• burn up : MWd/kgHM (default), MWd/tHM

• flux : 1/cm2/s (default)

• power : MW/cm3 (default), MW, W/gHM

• nuclide fission power: MW/cm3 (default), MW, W/gHM

• fission yield data : no unit (dimensionless)

• activity : Bq/cm3 (default), Bq, Ci/cm3, Ci

• decay heat : MW/cm3 (default), MW, W/gHM

NUCLEAR DATA

This nuclear data distribution is a continuous-energy nuclear data libraries in PENDF format (suitable for VESTA) and ACE format (suitable for any MCNP(X) version and MORET).

These nuclear data libraries were all generated using NJOY 99.259 using the same reconstruction tolerances (0.10 %).

These nuclear data libraries are based on JEF 2.2, JEFF 3.1, ENDF/B-VI.8
and ENDF/B-VII.0 nuclear data evaluations and are available at various temperatures: 293.6, 300, 600, 900, 1200, 1500 and 1800 K.

The JEF 2.2, JEFF 3.1 and ENDF/B-VII.0 data libraries also have S(a,b) ACE files
associated to them for a number of materials: H in H2O, H in CH2, Be
metal, Be in BeO and graphite.

The following nuclides and elements are available (for the given evaluation source):

JEF 2.2:
H1, H2, H3, HE3, HE4, LI6, LI7, BE9, B10, B11, C, N14, N15, O16, O17, F19, NA22, NA23, MG, AL27, SI, P31, S32, S33, S34, S36, CL, AR36, AR38, AR40, K, CA, TI, V, CR50, CR52, CR53, CR54, MN55, FE54, FE56, FE57, FE58, CO58, CO58M, CO59, NI58, NI59, NI60, NI61, NI62, NI64, CU, ZN64, GA, GE72, GE73, GE74, GE76, AS75, SE74, SE76, SE77, SE78, SE80, SE82, BR79, BR81, KR78, KR80, KR82, KR83, KR84, KR85, KR86, RB85, RB86, RB87, SR84, SR86, SR87, SR88, SR89, SR90, Y89, Y90, Y91, ZR, ZR90, ZR91, ZR92, ZR93, ZR94, ZR95, ZR96, NB93, NB94, NB95, MO, MO92, MO94, MO95, MO96, MO97, MO98, MO99, MO100, TC99, RU96, RU98, RU99, RU100, RU101, RU102, RU103, RU104, RU105, RU106, RH103, RH105, PD102, PD104, PD105, PD106, PD107, PD108, PD110, AG107, AG109, AG111, CD, CD106, CD110, CD111, CD112, CD113, CD114, CD115M, CD116, IN113, IN115, SN112, SN114, SN115, SN116, SN117, SN118, SN119, SN120, SN122, SN123, SN124, SN125, SN126, SB121, SB123, SB124, SB125, SB126, TE120, TE122, TE123, TE124, TE125, TE126, TE127M, TE128, TE129M, TE130, TE132, I127, I129, I130, I131, I135, XE124, XE126, XE128, XE129, XE130, XE131, XE132, XE133, XE134, XE135, XE136, CS133, CS134, CS135, CS136, CS137, BA134, BA135, BA136, BA137, BA138, BA140, LA139, LA140, CE140, CE141, CE142, CE143, CE144, PR141, PR142, PR143, ND142, ND143, ND144, ND145, ND146, ND147, ND148, ND150, PM147, PM148, PM148M, PM149, PM151, SM144, SM147, SM148, SM149, SM150, SM151, SM152, SM153, SM154, EU151, EU152, EU153, EU154, EU155, EU156, EU157, GD154, GD155, GD156, GD157, GD158, GD160, TB159, TB160, DY160, DY161, DY162, DY163, DY164, HO165, ER166, ER167, LU175, LU176, HF174, HF176, HF177, HF178, HF179, HF180, TA181, TA182, W182, W183, W184, W186, RE185, RE187, AU197, PB, BI209, TH230, TH232, PA231, PA233, U232, U233, U234, U235, U236, U237, U238, NP237, NP238, NP239, PU236, PU237, PU238, PU239, PU240, PU241, PU242, PU243, PU244, AM241, AM242, AM242M, AM243, CM241, CM242, CM243, CM244, CM245, CM246, CM247, CM248, BK249, CF249, CF250, CF251, CF252, CF253, ES253

JEFF 3.1:
H1, H2, H3, HE3, HE4, LI6, LI7, BE9, B10, B11, C, N14, N15, O16, O17, F19, NA22, NA23, MG24, MG25, MG26, AL27, SI28, SI29, SI30, P31, S32, S33, S34, S36, CL35, CL37, AR36, AR38, AR40, K39, K40, K41, CA40, CA42, CA43, CA44, CA46, CA48, SC45, TI46, TI47, TI48, TI49, TI50, V, CR50, CR52, CR53, CR54, MN55, FE54, FE56, FE57, FE58, CO58, CO58M, CO59, NI58, NI59, NI60, NI61, NI62, NI64, CU63, CU65, ZN, GA, GE70, GE72, GE73, GE74, GE76, AS75, SE74, SE76, SE77, SE78, SE79, SE80, SE82, BR79, BR81, KR78, KR80, KR82, KR83, KR84, KR85, KR86, RB85, RB86, RB87, SR84, SR86, SR87, SR88, SR89, SR90, Y89, Y90, Y91, ZR90, ZR91, ZR92, ZR93, ZR94, ZR95, ZR96, NB93, NB94, NB95, MO92, MO94, MO95, MO96, MO97, MO98, MO99, MO100, TC99, RU96, RU98, RU99, RU100, RU101, RU102, RU103, RU104, RU105, RU106, RH103, RH105, PD102, PD104, PD105, PD106, PD107, PD108, PD110, AG107, AG109, AG110M, AG111, CD106, CD108, CD110, CD111, CD112, CD113, CD114, CD115M, CD116, IN113, IN115, SN112, SN114, SN115, SN116, SN117, SN118, SN119, SN120, SN122, SN123, SN124, SN125, SN126, SB121, SB123, SB124, SB125, SB126, TE120, TE122, TE123, TE124, TE125, TE126, TE127M, TE128, TE129M, TE130, TE132, I127, I129, I130, I131, I135, XE124, XE126, XE128, XE129, XE130, XE131, XE132, XE133, XE134, XE135, XE136, CS133, CS134, CS135, CS136, CS137, BA130, BA132, BA134, BA135, BA136, BA137, BA138, BA140, LA138, LA139, LA140, CE140, CE141, CE142, CE143, CE144, PR141, PR142, PR143, ND142, ND143, ND144, ND145, ND146, ND147, ND148, ND150, PM147, PM148, PM148M, PM149, PM151, SM144, SM147, SM148, SM149, SM150, SM151, SM152, SM153, SM154, EU151, EU152, EU153, EU154, EU155, EU156, EU157, GD152, GD154, GD155, GD156, GD157, GD158, GD160, TB159, TB160, DY160, DY161, DY162, DY163, DY164, HO165, ER162, ER164, ER166, ER167, ER168, ER170, LU175, LU176, HF174, HF176, HF177, HF178, HF179, HF180, TA181, TA182, W182, W183, W184, W186, RE185, RE187, OS, IR191, IR193, PT, AU197, HG196, HG198, HG199, HG200, HG201, HG202, HG204, TL, PB204, PB206, PB207, PB208, BI209, RA223, RA224, RA225, RA226, AC225, AC226, AC227, TH227, TH228, TH229, TH230, TH232, TH233, TH234, PA231, PA232, PA233, U232, U233, U234, U235, U236, U237, U238, NP235, NP236, NP237, NP238, NP239, PU236, PU237, PU238, PU239, PU240, PU241, PU242, PU243, PU244, PU246, AM241, AM242, AM242M, AM243, AM244, AM244M, CM240, CM241, CM242, CM243, CM244, CM245, CM246, CM247, CM248, CM249, CM250, BK247, BK249, BK250, CF249, CF250, CF251, CF252, CF254, ES253, ES254, ES255, FM255

ENDF/B-VI.8:
H1, H2, H3, HE3, HE4, LI6, LI7, BE9, B10, B11, C, N14, N15, O16, O17, F19, NA23, MG, AL27, SI, SI28, SI29, SI30, P31, S, S32, CL, CL35, CL37, AR40, K, CA, SC45, TI, V, CR50, CR52, CR53, CR54, MN55, FE54, FE56, FE57, FE58, CO59, NI58, NI59, NI60, NI61, NI62, NI64, CU63, CU65, GA, GE72, GE73, GE74, GE76, AS75, SE74, SE76, SE77, SE78, SE80, SE82, BR79, BR81, KR78, KR80, KR82, KR83, KR84, KR85, KR86, RB85, RB86, RB87, SR84, SR86, SR87, SR88, SR89, SR90, Y89, Y90, Y91, ZR, ZR90, ZR91, ZR92, ZR93, ZR94, ZR95, ZR96, NB93, NB94, NB95, MO, MO92, MO94, MO95, MO96, MO97, MO98, MO99, MO100, TC99, RU96, RU98, RU99, RU100, RU101, RU102, RU103, RU104, RU105, RU106, RH103, RH105, PD102, PD104, PD105, PD106, PD107, PD108, PD110, AG107, AG109, AG111, CD, CD106, CD108, CD110, CD111, CD112, CD113, CD114, CD115M, CD116, IN, IN113, IN115, SN112, SN114, SN115, SN116, SN117, SN118, SN119, SN120, SN122, SN123, SN124, SN125, SN126, SB121, SB123, SB124, SB125, SB126, TE120, TE122, TE123, TE124, TE125, TE126, TE127M, TE128, TE129M, TE130, TE132, I127, I129, I130, I131, I135, XE124, XE126, XE128, XE129, XE130, XE131, XE132, XE133, XE134, XE135, XE136, CS133, CS134, CS135, CS136, CS137, BA134, BA135, BA136, BA137, BA138, BA140, LA139, LA140, CE140, CE141, CE142, CE143, CE144, PR141, PR142, PR143, ND142, ND143, ND144, ND145, ND146, ND147, ND148, ND150, PM147, PM148, PM148M, PM149, PM151, SM144, SM147, SM148, SM149, SM150, SM151, SM152, SM153, SM154, EU151, EU152, EU153, EU154, EU155, EU156, EU157, GD152, GD154, GD155, GD156, GD157, GD158, GD160, TB159, TB160, DY160, DY161, DY162, DY163, DY164, HO165, ER166, ER167, LU175, LU176, HF, HF174, HF176, HF177, HF178, HF179, HF180, TA181, TA182, W, W182, W183, W184, W186, RE185, RE187, IR191, IR193, AU197, PB206, PB207, PB208, BI209, TH230, TH232, PA231, PA232, PA233, U232, U233, U234, U235, U236, U237, U238, NP236, NP237, NP238, NP239, PU236, PU237, PU238, PU239, PU240, PU241, PU242, PU243, PU244, AM241, AM242, AM242M, AM243, CM241, CM242, CM243, CM244, CM245, CM246, CM247, CM248, BK249, CF249, CF250, CF251, CF252, CF253, ES253

ENDF/B-VII.0:
H1, H2, H3, HE3, HE4, LI6, LI7, BE7, BE9, B10, B11, C, N14, N15, O16, O17, F19, NA22, NA23, MG24, MG25, MG26, AL27, SI28, SI29, SI30, P31, S32, S33, S34, S36, CL35, CL37, AR36, AR38, AR40, K39, K40, K41, CA40, CA42, CA43, CA44, CA46, CA48, SC45, TI46, TI47, TI48, TI49, TI50, V, CR50, CR52, CR53, CR54, MN55, FE54, FE56, FE57, FE58, CO58, CO58M, CO59, NI58, NI59, NI60, NI61, NI62, NI64, CU63, CU65, ZN, GA69, GA71, GE70, GE72, GE73, GE74, GE76, AS74, AS75, SE74, SE76, SE77, SE78, SE79, SE80, SE82, BR79, BR81, KR78, KR80, KR82, KR83, KR84, KR85, KR86, RB85, RB86, RB87, SR84, SR86, SR87, SR88, SR89, SR90, Y89, Y90, Y91, ZR90, ZR91, ZR92, ZR93, ZR94, ZR95, ZR96, NB93, NB94, NB95, MO92, MO94, MO95, MO96, MO97, MO98, MO99, MO100, TC99, RU96, RU98, RU99, RU100, RU101, RU102, RU103, RU104, RU105, RU106, RH103, RH105, PD102, PD104, PD105, PD106, PD107, PD108, PD110, AG107, AG109, AG110M, AG111, CD106, CD108, CD110, CD111, CD112, CD113, CD114, CD115M, CD116, IN113, IN115, SN112, SN113, SN114, SN115, SN116, SN117, SN118, SN119, SN120, SN122, SN123, SN124, SN125, SN126, SB121, SB123, SB124, SB125, SB126, TE120, TE122, TE123, TE124, TE125, TE126, TE127M, TE128, TE129M, TE130, TE132, I127, I129, I130, I131, I135, XE123, XE124, XE126, XE128, XE129, XE130, XE131, XE132, XE133, XE134, XE135, XE136, CS133, CS134, CS135, CS136, CS137, BA130, BA132, BA133, BA134, BA135, BA136, BA137, BA138, BA140, LA138, LA139, LA140, CE136, CE138, CE139, CE140, CE141, CE142, CE143, CE144, PR141, PR142, PR143, ND142, ND143, ND144, ND145, ND146, ND147, ND148, ND150, PM147, PM148, PM148M, PM149, PM151, SM144, SM147, SM148, SM149, SM150, SM151, SM152, SM153, SM154, EU151, EU152, EU153, EU154, EU155, EU156, EU157, GD152, GD153, GD154, GD155, GD156, GD157, GD158, GD160, TB159, TB160, DY156, DY158, DY160, DY161, DY162, DY163, DY164, HO165, HO166M, ER162, ER164, ER166, ER167, ER168, ER170, LU175, LU176, HF174, HF176, HF177, HF178, HF179, HF180, TA181, TA182, W182, W183, W184, W186, RE185, RE187, IR191, IR193, AU197, HG196, HG198, HG199, HG200, HG201, HG202, HG204, PB204, PB206, PB207, PB208, BI209, RA223, RA224, RA225, RA226, AC225, AC226, AC227, TH227, TH228, TH229, TH230, TH232, TH233, TH234, PA231, PA232, PA233, U232, U233, U234, U235, U236, U237, U238, U239, U240, U241, NP235, NP236, NP237, NP238, NP239, PU236, PU237, PU238, PU239, PU240, PU241, PU242, PU243, PU244, PU246, AM241, AM242, AM242M, AM243, AM244, AM244M, CM241, CM242, CM243, CM244, CM245, CM246, CM247, CM248, CM249, CM250, BK249, BK250, CF249, CF250, CF251, CF252, CF253, CF254, ES253, ES254, ES255, FM255

The basic tasks of a true depletion code can be summarized as follows for every step in the evolution calculation:

• perform a steady state transport calculation and update the spectral and spatial averaged one group yields, cross sections (for every possible nuclide and reaction in the transmutation chains), flux values and other relevant data for use by the depletion module (for every depletion zone in the calculation);

• solve the Bateman equations for every depletion zone in the problem using the data derived by the transport calculation;

• pass on the new material compositions for the next step.

If need be, a special predictor-corrector treatment can be applied when the time steps are too long to alleviate the impact of the spectral changes over the time step.

VESTA automates this process by interfacing a Monte Carlo transport module with the depletion module. The complete VESTA input file consists of two distinct parts, the first part being the VESTA input related to the depletion calculation (irradiation history, the materials to burn, etc.) and the second part being the Monte Carlo input file with the geometry and material compositions.

The current version of VESTA requires a working version of MCNP or MCNPX and ORIGEN 2.2. Existing ORIGEN 2.2 executables will most likely not function with VESTA. Because VESTA recalculates a large number of reaction rates, it is possible that the size of the transition matrix to be used in the resolution of the Bateman equations no longer fits in the default memory allocation of ORIGEN 2.2. In order to make ORIGEN 2.2 work with VESTA, it must be recompiled with a larger memory allocation. The size of the arrays used by ORIGEN 2.2 are determined at the compilation of the code and can be found in the PARAMS.O2 file included in the source code of ORIGEN 2.2. The VESTA distribution contains an updated PARAMS.O2 file that replaces this file in the ORIGEN 2.2 code distribution from the NEA data bank or RSICC.

The total calculation time depends on the complexity and required precision for a given case. A large part of the calculation time is spent running MCNP(X) (which is run at least once for every step in the irradiation history, depending on the predictor-corrector algorithm chosen by the user).

See 3. DESCRIPTION OF PROGRAM

MCNP, MCNPX, ORIGEN 2.2. These packages are not included and must be requested separately.

Background documentation:

• W. Haeck, B. Cochet, L. Aguiar, "Burn-up dependent isomeric branching ratio treatment", Nucl. Sci. Eng., 171, pp 52-68 (2007)

• W. Haeck, B. Verboomen, "An Optimum Approach to Monte Carlo Burn-Up", Nucl. Sci. Eng., 156, pp 180-196 (2007)

• W. Haeck, "An Optimum Approach to Monte Carlo Burn-Up", PhD Thesis, Ghent University, Belgium (2007)

Any PC using a 32 or 64 bit Linux operating system should be able to run VESTA. VESTA has been tested on Ubuntu 11.10, 12.04 and 12.10.

Any PC using a 32 or 64 bit Linux operating system, a 32 or 64 bit Windows (XP, Vista or 7) or MacOS X should be able to run AURORA. AURORA has been tested on Ubuntu 12.04 and 12.10, Windows XP and 7 and MacOS X.

No sources are included.

VESTA can be launched using a python 2.5 script included in this distribution. Basic bash scripts are provided for ORIGEN 2.2 and MCNP(X)

VESTA is written in C++. The interface with MCNP(X) and ORIGEN 2.2 is implemented using system calls (using a C++ Standard Library function) using MCNP(X) and ORIGEN 2.2 executables available on the system.

AURORA can be launched using a script (for each OS type) included in this distribution.

W. HAECK
IRSN
BP 17
92262 Fontenay aux Roses cedex
France