def METHOD_NAME(blk):
    """
    Method for costing Magprex reactor unit.
    """
    t0 = blk.flowsheet().time.first()
    # Get parameter dict from database
    parameter_dict = blk.unit_model.config.database.get_unit_operation_parameters(
        blk.unit_model._tech_type, subtype=blk.unit_model.config.process_subtype
    )
    # Get costing parameter sub-block for this technology
    HRT, size_cost = blk.unit_model._get_tech_parameters(
        blk,
        parameter_dict,
        blk.unit_model.config.process_subtype,
        ["HRT", "sizing_cost"],
    )
    # Add cost variable and constraint
    blk.capital_cost = pyo.Var(
        initialize=1,
        units=blk.config.flowsheet_costing_block.base_currency,
        bounds=(0, None),
        doc="Capital cost of unit operation",
    )
    expr = pyo.units.convert(
        blk.unit_model.properties_in[t0].flow_vol * HRT * size_cost,
        to_units=blk.config.flowsheet_costing_block.base_currency,
    )
    # Determine if a costing factor is required
    blk.unit_model._add_cost_factor(
        blk, parameter_dict["capital_cost"]["cost_factor"]
    )
    blk.capital_cost_constraint = pyo.Constraint(
        expr=blk.capital_cost == blk.cost_factor * expr
    )
    # Register flows
    blk.config.flowsheet_costing_block.cost_flow(
        blk.unit_model.electricity[t0], "electricity"
    )
    blk.config.flowsheet_costing_block.cost_flow(
        blk.unit_model.MgCl2_flowrate[t0], "magnesium_chloride"
    )