Specification

↩ Back

Each simulation task is defined in a single configuration file written in YAML format.

Input units are standard SI units, except time is in years.

Basic simulation settings

Maximum simulation time step [years]

Example: dt: 5

Total simulation time [years]

Example: time: 2000000

Maximum number of iterations. If this limit is reached, the simulation stops (likely due to numerical instability).

Example: max_iter: 24

List of physical processes included in the simulation

Available options:

• conversion – Radioactive decay of radionuclides.
• max_solubility – Maximum solubility limits of elements (otherwise unlimited).
• diffusion – Diffusion of radionuclides through the bentonite barrier.
• sorption – Sorption of radionuclides in the bentonite (linear Henry isotherm).

Defines the output data format

Time interval for output records [years]

Example: step_time: 500

Quantities (columns in the output CSV)

quantities:

• fuel_m_kg – Total SNF (in rods, i.e., intact, undissolved) [kg]
• fuel_n_mol – Total SNF [mol]
• fuel_A_Bq – Total SNF [Bq]
• deg_m_kg – Degraded SNF (“sand”) [kg]
• deg_n_mol – Degraded SNF [mol]
• fuel+deg_m_kg – Total SNF (degraded + intact) [kg]
• cont.water_c_kg/m3 – Container: concentration in water [kg/m³]
• cont.water_sat_% – Container: concentration as % of solubility
• cont.water_c_mol/m3 – Container: concentration in water [mol/m³]
• cont.water_A_Bq – Container: activity in water [Bq]
• cont.water_AV_Bq/m3 – Container: activity in water [Bq/m³]
• bent.inner.bound.water_c_kg/m3 – Inner edge of bentonite: concentration in water [kg/m³]
• bent.inner.bound.water_c_mol/m3 – Inner edge of bentonite: concentration in water [mol/m³]
• bent.1/4.water_c_kg/m3 – 1/4 thickness of bentonite from inner edge [kg/m³]
• bent.1/4.water_c_mol/m3 – Same, in [mol/m³]
• bent.1/2.water_c_kg/m3 – Half thickness from inner edge [kg/m³]
• bent.1/2.water_c_mol/m3 – Same, in [mol/m³]
• bent.3/4.water_c_kg/m3 – 3/4 thickness from inner edge [kg/m³]
• bent.3/4.water_c_mol/m3 – Same, in [mol/m³]
• bent.outer.bound.water_c_kg/m3 – Outer edge of bentonite: concentration [kg/m³]
• bent.outer.bound.water_c_mol/m3 – Outer edge of bentonite: concentration [mol/m³]
• bent.layers.water_c_mol/m3 – Layer-wise concentration in water [mol/m³] (default 5 cm steps)
• bent.layers.water_c_kg/m3 – Layer-wise concentration in water [kg/m³]
• bent.water_m_kg – Total dissolved mass in bentonite [kg]
• bent.rock_m_kg – Sorbed mass in bentonite [kg]
• bent_m_kg – Total radionuclide mass in bentonite [kg]
• granit.water_m_kg – Cumulative outflow from bentonite [kg]
• granit.water_n_mol – Same in [mol]
• granit.water_m(cumsum)_kg – Cumulative outflow without radioactive decay [kg]
• granit.water_n(cumsum)_mol – Same in [mol]

Isotopes (columns in the output CSV)

Example: isotopes: [all]

Elements (columns in the output CSV)

Example: elements: [all]

Stores sum over all isotopes/elements

Example: summary_quantity: no

Stores output of fuel_degradation_function

Example: degradation_rate: yes

Sets column order in the output CSV.

“Mount” means amount (mass/quantity).

Options:

• quantity – Columns sorted by quantity type.
• quantity/name – First by quantity, then by isotope name.
• quantity/initial_mount – First by quantity, then by initial isotope mass.
• name/quantity – First by isotope name, then quantity.
• initial_mount/quantity – First by initial isotope mass, then quantity.

Example: columns_ordering: quantity

Column separator and decimal point format

Options:

• dec._col, – Decimal point: ., separator: ,
• dec._col; – Decimal point: ., separator: ;
• dec,_col; – Decimal point: ,, separator: ;
• dec._colt – Decimal point: ., separator: tab

Example: separators: dec,_col;

Number format

Options:

• G – general (e.g., 0.0)
• E – exponential (e.g., 0.0E+0)
  • 4E – same, with 4 decimals
• F – fixed number of decimals
  • 4F – fixed 4 decimals

Example: number_format: G

Path to output CSV file

Example: file_name: .\edu.csv

Selection of simulation statistical outputs

Options:

• cont_max_c – Max concentration of radionuclides in the container
• bent_bound_max_c – Max concentration on outer edge of bentonite
• granit_inflow – Cumulative outflow into surrounding rock

Disposal container parameters

Outer radius of container (used for bentonite geometry)

Example: radius: 0.4

Container height (for geometry only)

Example: height: 4

Internal free volume of the container

Example: free_volume: 0.2

Time from simulation start to water inflow into container (start of wet phase) [years]

Example: T0_water_inflow_time: 2e5

Fuel degradation kinetics

Switch

Options:

• user_def – Piecewise linear function (power block ignored)
• power – Power-law function (user_def block ignored)

Piecewise linear function

Time since T0_water_inflow_time. Must have at least two values, starting with zero.

Example: times: [0, 1000000]

Percentage of degraded SNF

• First value must be irf (initial fraction),
• Last must be 100 (fully degraded)

Example: values_%: [irf, 100]

Power-law function

Time at which function reaches 100%

Example: degradation_time_span: 8e5

Exponent

Example: power_factor: 0.3

Time discretization for generating the piecewise function

Example: time_step: 100

Dissolution

Options:

• no – Elements dissolve up to their own solubility limit
• yes – Also limited by the controlling_element ratio

Example: controlled: yes

Element controlling dissolution of others

Example: controlling_element: U

Time-dependent contact area of container shell — piecewise linear

First value must be zero

Example: times: [0]

Any value; the last one persists for the rest of simulation

Example: values_%: [100]

Fraction of container water leaking directly into granite [%/year]

Example: direct_outflow_into_granite_%/year: 0

Thickness of the bentonite barrier [m]

Example: width: 0.7

Discretization step in thickness [m]

Example: dr: 0.05

Dry bulk density of bentonite [kg/m³]

Example: density: 1500

Outer boundaries of zones (from the inner edge)

Example: zones_outer_bound: [0.7]

The following 3 items define time-dependent properties in zones (piecewise linear functions):
porosity,
De_b_modification, and
Kd_b_modification.

Porosity

Example: times: [0]

Multiple zones possible

Example: zone1_%: [30]

Diffusion coefficient modifier

Example: times: [0]

Example: zone1_%: [100]

Sorption coefficient modifier

Example: times: [0]

Example: zone1_%: [100]

Boundary condition at the outer edge of the bentonite barrier.

Options:

• granite_layer – Transfer into the surrounding rock.
• zero_conc – Zero concentration at the boundary (i.e. instant removal of material from bentonite edge).

Example: bound_model: zero_conc

Only used when: bound_model: granite_layer

Thickness of the rock layer

Example: width: 0.002

Where the effective diffusion coefficient is specified

Options:

• De_b_%: defined on the line below
• De_g : defined in the isotopes block (further below)

Example: De_source: De_b_%

Effective diffusion coefficient in granite defined as a percentage of De in bentonite.

Example: De_b_%: 100

Boundary concentration in granite as a percentage of bentonite outer boundary concentration

Example: conc_by_bentonite_bound_conc_%: 0

Definition of isotopes included in the simulation.

Name of isotope (must include element and mass number)

Example: name: C14

Molar mass of isotope [kg/mol]

Example: M_kg/mol: 0.014

Half-life of the isotope [years]

Example: T_1/2_year: 5700

Decay product (must be listed among isotopes)

Example: conversion_to: waste

Initial isotope mass in SNF

Options:

• init_a_bq – Initial activity in spent fuel [Bq], i.e., disintegrations per second.
• init_n_mol – Initial amount in moles [mol].

Example: init_m_kg: 0.000882

Instantly Released Fraction (IRF) – percent of init_m_kg

Example: irf_%: 10

Solubility limit [mol/m³]

Example: c_max_mol/m3: inf

Effective diffusion coefficient in bentonite [m²/s]

Example: De_b_m2/s: 1.2e-10

Sorption coefficient in bentonite [m³/kg]

Example: Kd_b_m3/kg: 0

Effective diffusion coefficient in granite [m²/s]

Example: De_g_m2/s: 5e-15