fz-Simulate

fz wrapper for Studsvik SIMULATE (core simulator) and for the full CASMO5 → CMS-LINK → SIMULATE chain, so that lattice and core parameters can be varied in one parametric study, run locally, over SSH or on SLURM.

Two models:

Model	Input	What a case runs
Simulate	one SIMULATE deck (+ library)	SIMULATE
CasmoSimulate	a case directory (see below)	every CASMO deck, then CMS-LINK, then SIMULATE

CASMO alone is covered by fz-Casmo.

Requirements

• fz > 1.2 (installing both models of this repository needs the fix installing every .fz/models/*.json; with fz 1.2 only one model gets installed, copy the other one from .fz/models/ by hand)
• licensed Studsvik codes, each located by (first match wins) *_CMD (full command), *_PATH (install dir, launcher in it or in bin/), or the launcher name on PATH:

Code	Command	Install dir	Launcher names tried	Options
CASMO5	CASMO_CMD	CASMO_PATH	cas5	CASMO_OPTS (default -p -k)
CMS-LINK	CMSLINK_CMD	CMSLINK_PATH	cmslink5, cmslink, link5	CMSLINK_OPTS
SIMULATE	SIMULATE_CMD	SIMULATE_PATH	sim5, simulate5, simulate3, s3	SIMULATE_OPTS

The launcher names are defaults to be checked against your installation; setting the *_CMD variables avoids any guessing.

Quick start

fz install model Simulate
export CASMO_CMD=/opt/studsvik/bin/cas5 CMSLINK_CMD=... SIMULATE_CMD=...

# SIMULATE alone, library shared by all cases
fzr examples/Simulate/simulate.inp --model Simulate --input_static cms.lib \
    --input_variables '{"core_power": [100, 90, 80]}' --format json

# whole chain: vary a lattice parameter and a core parameter together
fzr examples/CasmoSimulate --model CasmoSimulate \
    --input_variables '{"enrichment_B": [4.2, 4.6, 4.95], "cycle_length": [16, 18]}' \
    --format json

import fz
res = fz.fzr("examples/CasmoSimulate",
             {"enrichment_B": [4.2, 4.6, 4.95]},
             model="CasmoSimulate", results_dir="results")
print(res[["enrichment_B", "boron", "fdh", "status"]])

Chain case layout (CasmoSimulate)

examples/CasmoSimulate/
├── casmo/fuel_A.inp     CASMO deck per segment (any number of *.inp)
├── casmo/fuel_B.inp
├── cmslink.inp          CMS-LINK deck: reads casmo/*.cax, writes the library
└── simulate.inp         SIMULATE deck: reads that library

Per case, the runner (.fz/calculators/CasmoSimulate.sh):

1. runs every casmo/*.inp (CASMO_JOBS at a time, default 1) and checks each produced its .out and .cax (log: casmo/<deck>.log);
2. runs CMS-LINK on cmslink.inp;
3. runs SIMULATE on simulate.inp.

A failed stage stops the chain; the exit status says where: 2 setup, 10 CASMO, 20 CMS-LINK, 30/31 SIMULATE. The file names can be changed with CHAIN_CASMO_DIR, CHAIN_CMSLINK_INPUT, CHAIN_SIMULATE_INPUT. The chain model has a 4 h timeout per case ("timeout" in .fz/models/CasmoSimulate.json).

Variables may appear in any file of the tree; fzi lists them all, and one fz case compiles all files with the same values. Lattice calculations are redone for every case: for studies that vary only core parameters, run the chain once and use the Simulate model with the resulting library as --input_static.

Input syntax

Same for both models and all decks: ${name} / ${name~default} variables, @{expr} Python formulas, *@ formula context lines, * comments.

The example decks are skeletons: they show the parameterization, not a complete core model. Replace their content with the decks of your methodology (core loading, geometry, CASMO branch cases for CMS-LINK), keeping the fz variables where needed.

Outputs

Parsed from the SIMULATE output (first *.out of the case directory not named cmslink*), one value per state/depletion step:

Output	Content
keff	k-effective
boron	boron concentration [ppm]
cycle_exposure	cycle exposure
fq, fdh	peaking factors
axial_offset	axial offset [%]
n_steps	number of steps found
casmo_decks, cax_files	(chain only) CASMO decks run, .cax files produced

Validation status: these parsers are provisional. They were written for the summary lines of a SIMULATE-3 style output (K-effective . . . 1.00000, Boron Conc. . . . 1234.5 ppm, ...) and have not yet been checked against real SIMULATE outputs. Add real excerpts in tests/fixtures/ (below) and adjust the regular expressions of .fz/models/*.json until the tests pass.

Tests

pip install funz-fz pytest
pytest tests/

No Studsvik code is needed: tests/mock/{cas5,cmslink,sim5} are fake launchers that carry data along the chain (CASMO k-inf → library → SIMULATE boron), so the tests check that a parameter of a CASMO deck really reaches the SIMULATE result, plus alias discovery, --input_static handling, parallel CASMO runs and failure reporting.

Every tests/fixtures/<case>/ holding an expected.json is parsed with fzo and compared with it: this is where real SIMULATE outputs go to validate the parsers. tests/fixtures/synthetic_cycle/ is hand-written, not a SIMULATE output.

Remote execution

Add an alias next to localhost_Simulate.json, with the scripts installed on the remote side (Simulate.sh/CasmoSimulate.sh need cms_common.sh in the same directory):

{ "uri": "slurm://user@cluster:batch",
  "models": { "CasmoSimulate": "bash /path/to/CasmoSimulate.sh" } }

License

BSD 3-Clause License. See LICENSE.