The nds Command#

The NDSampler module provides the nds command to manage your perturbed nuclear data libraries.

Building a Perturbed Library (PENDF)#

Building a perturbed library using the PENDF method is done using the nds pendf command. It must be provided the path to a YAML file containing a structured description of what you want. It should contain the following information:

  • A summary element giving a short description of the perturbed library

  • A name element giving a name to your perturbed library

  • A reuse element telling what existing HDF5 library your perturbed library should rely on. This library should be installed with NDOmcer (i.e. it appears in ndo list)

  • A nsmp element telling how many samples should be created

  • A temperature element telling what temperature should be used for Doppler broadening

  • A kind element telling what nuclear data should be perturbed (for now, only xs is implemented)

  • A samples element, containing details about what nuclide you want to perturb

    • This element contains sub-element structured like so:

      nuclide: xs_library cov_library@group_structure

Here is a sample of what an nds pendf input file looks like:

summary: Sampling Pu239 using TENDL2023 Covariances and a JEFF-3.3 base
name: jeff33-Pu239
reuse: jeff33
nsmp: 10
temperature: 600
kind: xs
samples:
  Pu239: jeff33 tendl2023@ECCO-33

This will create 10 perturbed libraries in which Pu239 cross-sections from JEFF-3.3 are perturbed using covariance matrices from TENDL-2023 on an ECCO-33 group structure, at a temperature of 600K. All other nuclide cross-sections are taken from the jeff33 library installed with NDOmcer. The mapping to nominal cross-sections are done in the generated cross_sections.xml files rather than through the duplication of HDF5 files.

Building a Perturbed Library (HDF5)#

Building a perturbed library using the HDF5 method is done using the nds hdf5 command. It must be provided the path to a YAML file containing a structured description of what you want. It should contain the following information:

  • A summary element giving a short description of the perturbed library

  • A name element giving a name to your perturbed library

  • A reuse element telling what existing HDF5 library your perturbed library should rely on. This library should be installed with NDOmcer (i.e. it appears in ndo list)

  • A nsmp element telling how many samples should be created

  • A kind element telling what nuclear data should be perturbed (for now, only xs is implemented)

  • A samples element, containing details about what nuclide you want to perturb

    • This element contains sub-element structured like so:

      nuclide: xs_library cov_library@group_structure

Here is a sample of what an nds hdf5 input file looks like:

summary: Sampling Pu239 using TENDL2023 Covariances and a JEFF-3.3 base
name: jeff33-Pu239
reuse: jeff33
nsmp: 10
kind: xs
samples:
  Pu239: jeff33 tendl2023@ECCO-33

This will create 10 perturbed libraries in which Pu239 cross-sections from JEFF-3.3 are perturbed using covariance matrices from TENDL-2023 on an ECCO-33 group structure, at a temperature of 600K. All other nuclide cross-sections are taken from the jeff33 library installed with NDOmcer. The mapping to nominal cross-sections are done in the generated cross_sections.xml files rather than through the duplication of HDF5 files.

Note that the input file is essentialy the same as the PENDF one. The main difference between the two method is that nds pendf generates covariance matrices on the fly using ERRORR whereas nds hdf5 uses preprocessed matrices written on disk.

Building Covariance Matrices#

The nds cov command allows you to build covariance matrices for a given multigroup energy structure, using the ERRORR module from NJOY.

For instance, if you have the TENDL-2023 library installed through NDFetcher, you can run:

$ nds cov tendl23 --ign ECCO-33

The ign argument must correspond to the name of the desired group structure, or to the associated number in NJOY. The following table show what group structures are available.

ign

Name

2

CSWEG-239

3

LANL-30

4

ANL-27

5

RRD-50

6

GAM-I-68

7

GAM-II-100

8

LASER-THERMOS-35

9

EPRI-CPM-69

10

LANL-187

11

LANL-70

12

SAND-II-620

13

LANL-80

14

EURLIB-100

15

SAND-IIA-640

16

VITAMIN-E-174

17

VITAMIN-J-175

18

XMAS-NEA-LANL

19

ECCO-33

20

ECCO-1968

21

TRIPOLI-315

22

XMAS-LWPC-172

23

VIT-J-LWPC-175

24

SHEM-CEA-281

25

SHEM-EPM-295

26

SHEM-CEA-EPM-361

27

SHEM-EPM-315

28

RAHAB-AECL-89

29

CCFE-660

30

UKAEA-1025

31

UKAEA-1067

32

UKAEA-1102

33

UKAEA-142

34

LANL-618

Additionally you can provide the -j flag with an integer value to use multiple processes to build the matrices. If the matrix database already exists, you can regenerate it from scratch by providing the --clean flag.

Listing Installed Perturbed Libraries#

The nds list command gives you a summary of what perturbed libraries you have installed:

$ nds list
Kind    Name          Base      Samples    Nuclides  Description
------  ------------  ------  ---------  ----------  -----------------------------------------
HDF5    jeff33-Pu239  jeff33         10           1  Create sample for Pu239 nuclide in jeff33
PENDF   jeff33-Pu239  jeff33         10           1  Create sample for Pu239 nuclide in jeff33