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classify

Waste classification, where the answer is a category rather than an index.

classify

Waste classification, where the answer is a category rather than an index.

The US and UK both sort waste into named classes rather than reporting a single ratio. The NRC's classes come out of the same sum-of-fractions machinery as a clearance index, applied to several tables and combined by rules in 10 CFR 61.55. The UK's categories instead compare gross alpha and beta or gamma activity against concentration thresholds, so they need no per-nuclide table at all and are computed directly.

Classes:

  • UKWasteCategory –

    The UK waste category of a material, with the numbers behind it.

Functions:

  • nrc_waste_class –

    Classify a material for near-surface disposal under 10 CFR 61.55.

  • alpha_activity –

    Activity from alpha emission, weighted by each nuclide's alpha branch.

  • beta_gamma_activity –

    Activity from everything that is not alpha emission.

  • uk_waste_category –

    Classify a material against the UK solid low level waste categories.

UKWasteCategory dataclass 

UKWasteCategory(category: str, alpha: float, beta_gamma: float, tritium_and_c14: float, total: float, reason: str)

The UK waste category of a material, with the numbers behind it.

Attributes:

  • category (str) –

    "VLLW", "LLW" or "ILW".

  • alpha (float) –

    Alpha activity in Bq/g.

  • beta_gamma (float) –

    Beta and gamma activity in Bq/g.

  • tritium_and_c14 (float) –

    Tritium plus carbon-14 activity in Bq/g, which share their own VLLW allowance.

  • total (float) –

    Total activity in Bq/g.

  • reason (str) –

    Why this category and not the one below it.

nrc_waste_class 

nrc_waste_class(material: Material, *, metal: bool = False) -> str

Classify a material for near-surface disposal under 10 CFR 61.55.

Applies the sum of fractions rule to Table 1 and Table 2 and combines the results with the rules in paragraphs 61.55(a)(3) to (a)(7).

Parameters:

  • material

    (Material) –

    The inventory to classify. Needs a density, since the NRC limits are volumetric.

  • metal

    (bool, default: False ) –

    Whether the material is activated metal, which the regulation treats with its own rows.

Returns:

  • str –

    "Class A", "Class B", "Class C" or "GTCC" for greater

  • str –

    than Class C.

alpha_activity 

alpha_activity(material: Material, units: str = 'Bq/g') -> float

Activity from alpha emission, weighted by each nuclide's alpha branch.

Bi-212 branches 35.94 percent alpha, so it contributes that share of its activity here and the rest to beta_gamma_activity.

Parameters:

  • material

    (Material) –

    The inventory.

  • units

    (str, default: 'Bq/g' ) –

    Any unit activity accepts.

beta_gamma_activity 

beta_gamma_activity(material: Material, units: str = 'Bq/g') -> float

Activity from everything that is not alpha emission.

Parameters:

  • material

    (Material) –

    The inventory.

  • units

    (str, default: 'Bq/g' ) –

    Any unit activity accepts.

uk_waste_category 

uk_waste_category(material: Material) -> UKWasteCategory

Classify a material against the UK solid low level waste categories.

Thresholds are from Policy for the Long Term Management of Solid Low Level Radioactive Waste in the United Kingdom (Defra and the Devolved Administrations, 2007), which defines LLW as not exceeding 4 GBq/te alpha or 12 GBq/te beta and gamma, and high volume VLLW as not exceeding 4 MBq/te total activity, with tritium allowed to 40 MBq/te.

Two limits of this classification are worth stating rather than hiding. The low volume VLLW category ("dustbin disposal") is defined per 0.1 cubic metre and per item, so it is a property of a consignment rather than of a material and is not decided here. The boundary above which waste becomes high level rather than intermediate is a thermal one, about 2 kW/m3, and needs decay heat rather than activity, so this returns ILW for everything above LLW.

Parameters:

  • material

    (Material) –

    The inventory to classify.

Returns: