heavy water
Enable an agent to recognise heavy water, assess its isotopic and chemical condition, and determine its suitability for a specified use.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise heavy water, assess its isotopic and chemical condition, and determine its suitability for a specified use.
Heavy water is water enriched in deuterium, the stable hydrogen isotope with one proton and one neutron, conventionally referring to deuterium oxide (D₂O), in which both hydrogen atoms are deuterium.
It can be Compare supplier labels and certificates after reconciling their isotopic-purity reporting bases.; Request or interpret isotope, chemical and radiological assays appropriate to the lot's intended use and history.; Select measured physical properties applicable to the lot's temperature, pressure and composition.; Qualify, reject or quarantine a lot against documented application requirements.; Identify when handling or moisture exposure requires resampling and requalification.; Route storage, transfer, recovery or disposal decisions to the applicable documented requirements..
Distinguishing features
Establish whether the name denotes the D2O molecular species or a material lot containing D2O, HDO and H2O.
Distinguish heavy water from ordinary water through measured isotopic composition rather than appearance or density alone.
Distinguish isotopic purity from chemical purity: a chemically clean lot can still contain more protium than its intended use permits.
Distinguish deuterium enrichment from tritium content or measured radioactivity; neither a heavy-water label nor a deuterium assay establishes radiological status.
Distinguish an accepted heavy-water grade from a nominally similar lot through application-specific limits and documented measurement conditions.
Scope
+ D2O identity and the boundary between heavy water and other deuterium-enriched water mixtures
+ Deuterium abundance, D2O/HDO/H2O composition and the reporting basis of isotopic purity
+ Chemical impurities, dissolved gases and separately assessed radioactive contamination
+ Phase, thermophysical properties and the conditions under which they were measured
+ Material-grade suitability, storage condition and changes caused by handling or use
+ Substance identifiers and applicable safety or transfer requirements supported by current sources
- Ordinary water properties except where they establish a relevant comparison or inherited behaviour
- Deuterium gas, tritiated water and other isotope-labelled substances as independent materials
- Heavy-water production plants and detailed enrichment processes
- Reactor design, operation and nuclear-material systems
- Spectrometers, experimental protocols and finished products containing heavy water
Characteristics
- Material identity and designation
- D2O molecular species; deuterium-enriched water mixture; declared commercial grade Prevents a molecular name from being treated as a complete description of a supplied material.
- Deuterium atom fraction
- atom % D among hydrogen isotopes, with denominator, method and uncertainty stated Provides a comparable enrichment measure when labels use different purity conventions.
- Water isotopologue composition
- Mole fractions of D2O, HDO and H2O; measured or inferred status Describes molecular composition without equating atom % D with mole % D2O.
- Chemical impurity profile
- Analyte-specific concentrations in mg/kg, µg/L or mol/L, with detection limits Identifies contamination that may compromise an application independently of isotope enrichment.
- Radiological condition
- Unassessed; assayed with radionuclide-specific activity in Bq/L or Bq/kg and detection limits Separates stable-isotope identity from contamination associated with a material's history.
- Phase and observation conditions
- Solid, liquid, vapour or multiphase; temperature in K or °C and pressure in Pa Makes state descriptions and property comparisons interpretable.
- Thermophysical property set
- Density in kg/m³, viscosity in Pa·s, transition temperatures in K or °C; composition and pressure specified Supports handling and calculations using values applicable to the actual material.
- Acidity measurement basis
- Reported pH reading or pD estimate, dimensionless, with calibration and conversion convention Prevents unqualified comparison of readings taken in different isotopic solvent compositions.
- Exposure and storage condition
- Seal status, opening history, moisture exposure, container compatibility and sampling date Helps determine whether an earlier composition certificate still represents the lot.
- Application qualification
- Lot linked to a named specification, version, test results and acceptance decision Makes suitability a supported decision for a particular use.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 17 findings · 27 questions.
Heavy-water identity Establish what the heavy-water designation refers to and how its identity is evidenced.
The D2O species, an enriched-water mixture and a commercial grade require different identity statements.
Species and material boundary
Separate molecular identity from the composition of a physical lot.
Meaning of heavy water
Record the intended sense of the name and any enrichment criterion used to apply it.
- Does this record describe D2O as a molecular species or a material containing multiple water isotopologues? definition
- What documented convention determines whether this enriched-water mixture is called heavy water? boundary
Identity evidence
Connect identifiers and supplier declarations to the substance and lot they actually describe.
Identifier and certificate scope
Record verified registry identifiers, grade names and certificate provenance without treating them as interchangeable evidence.
- Which CAS, PubChem and EC records were checked, and do they identify D2O or the supplied mixture? provenance
- Which supplier certificate identifies this lot, its declared grade and the date of its composition measurements? provenance
Isotopic and chemical composition Describe enrichment and contamination using explicit measurement bases.
Heavy-water suitability depends on isotope composition as well as conventional chemical purity.
Enrichment accounting
Make isotope assays and isotopologue estimates comparable.
Purity basis and isotopologues
Record what a purity percentage counts and distinguish measured species fractions from calculated ones.
- Is the reported enrichment atom % D, mole % D2O, a mass fraction or another quantity, and what is its denominator? measurement
- Were D2O, HDO and H2O fractions measured separately or inferred, and what assumptions and uncertainties support any inference? measurement
Non-water constituents
Identify impurities and additives that an isotope assay does not resolve.
Chemical purity evidence
Record relevant ions, organics, dissolved gases and deliberately added substances.
- Which impurities or additives have been assayed, in what units and with what detection limits? measurement
- Does the material remain a heavy-water lot, or should a formulated solution containing heavy water be represented by a neighbouring model? boundary
Physical and solvent state Represent phase, measurable properties and solvent measurements under stated conditions.
Values for ordinary water or idealised D2O cannot automatically describe every enriched-water lot.
Phase and thermophysical properties
Attach state and property observations to pressure, temperature and composition.
Conditioned property values
Record applicable density, viscosity and phase-transition data with their provenance.
- What phase is present at the recorded temperature, pressure and isotopic composition? measurement
- Which measured or reference density, viscosity, melting and boiling values apply, and what conditions and uncertainties accompany them? provenance
Isotopic solvent behaviour
Capture solvent observations whose interpretation depends on hydrogen-isotope composition.
Acidity and exchange context
Record acidity conventions and contact with exchangeable hydrogen when these affect use.
- Is acidity reported as an electrode pH reading or a pD estimate, and which calibration or conversion convention was used? measurement
- Which contacting solvents, solutes or surfaces could alter the relevant isotope composition through hydrogen exchange? boundary
Grade and use qualification Connect a lot's demonstrated properties to a specific intended application.
An acceptable spectroscopic solvent, tracer material and reactor-associated material need not satisfy the same requirements.
Application requirements
Define acceptance criteria without modelling the equipment or process that consumes the material.
Use-specific acceptance
Associate intended use with explicit enrichment, impurity and other material limits.
- Is the proposed use spectroscopy, isotope tracing, neutron moderation or another application, and which material specification governs it? definition
- Which isotope, chemical and radiological criteria must the lot satisfy before that use is authorised? action
Qualification status
Distinguish declared grade from demonstrated current suitability.
Evidence for release
Record acceptance evidence, unresolved deviations and triggers for renewed testing.
- Which current lot-specific results support acceptance, and which required properties remain untested? provenance
- What exposure, reuse or composition change would require the lot to be quarantined or requalified? action
Handling and control Preserve composition and establish the requirements applicable to the actual lot.
Moisture contact, service history and jurisdiction can change how heavy water must be assessed and handled.
Composition preservation
Track storage and handling conditions relevant to retained enrichment and cleanliness.
Container and exposure history
Record containment, opening and transfer history alongside the most recent representative assay.
- What container, seal and handling history support the claim that the recorded enrichment still represents this lot? provenance
- After suspected moisture ingress or contact with ordinary water, what sampling and assay are required before further use? action
Radiological and regulatory status
Determine hazard and transfer requirements from documented identity, composition, history and jurisdiction.
Lot-specific controls
Separate chemical classification, radionuclide assessment and applicable material controls.
- What service history or assay establishes tritium and other radionuclide status, including any detection limits or unresolved assessment need? provenance
- Which current safety data and jurisdictional sources establish applicable GHS classification, exposure limits if any, and storage, transfer or disposal requirements? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This is recalled knowledge, not a researched or source-verified record.
- Check supplier specifications for isotopic abundance, chemical purity and grade; atom % D is distinct from the percentage of molecules that are D₂O.
- Verify current jurisdiction-specific nuclear controls, transport requirements and product hazard classifications before operational use.
- Which of these check these first hold for the sense of heavy water this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- High-isotopic-purity deuterium oxide
- Reactor-grade heavy water
- Laboratory-grade heavy water
- Partially deuterium-enriched water
- Which of these kinds and varieties hold for the sense of heavy water this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- CAS Registry Number - 7789-20-0 - Identifies deuterium oxide.
- Chemical formula - D₂O or ²H₂O - D denotes deuterium; an enriched bulk sample can also contain HDO and H₂O.
- Which of these identifiers and schemes hold for the sense of heavy water this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Neutron moderator in heavy-water nuclear reactors.
- Coolant in some nuclear reactor designs.
- Deuterated solvent for nuclear magnetic resonance spectroscopy.
- Isotopic tracer in chemical and biological research.
- Isotopic contrast medium in neutron scattering experiments.
- Which of these real-world use hold for the sense of heavy water this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Molar mass of D₂O - Approximately 20.03 - g/mol
- Density of nearly pure liquid D₂O at 20 °C - Approximately 1.106 - g/cm³
- Melting point of nearly pure D₂O at atmospheric pressure - Approximately 3.82 - °C
- Normal boiling point of nearly pure D₂O - Approximately 101.4 - °C
- Deuterium isotopic abundance in high-purity laboratory material - Commonly 99.8-99.9; product-dependent - atom % D
- Which of these typical measurements hold for the sense of heavy water this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Substantial replacement of body water with heavy water disrupts biological processes through isotope effects.
- Exchange with ordinary water or atmospheric moisture reduces isotopic purity and can compromise experiments or reactor performance.
- Chemical impurities can impair suitability for nuclear or analytical applications independently of isotopic purity.
- Heavy water exposed to neutron irradiation can accumulate radioactive tritium; deuterium oxide itself is not intrinsically radioactive.
- Substituting heavy water for ordinary water can change reaction rates, equilibria and biological behavior.
- Which of these failure modes and hazards hold for the sense of heavy water this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Ordinary water - Its hydrogen is predominantly protium, whereas heavy water is enriched in deuterium.
- Semiheavy water - HDO has one protium and one deuterium atom per molecule; D₂O has two deuterium atoms.
- Tritiated water - Contains radioactive tritium rather than only stable hydrogen isotopes.
- Oxygen-18-enriched water - Its isotopic enrichment concerns oxygen rather than necessarily deuterium.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of heavy water this model covers, and on what evidence? provenance
What the second pass must settle
- Which authoritative definition and enrichment convention should delimit heavy water from more broadly deuterium-enriched water in this registry?
- Which verified identifiers and reference thermophysical values should be adopted, with what composition, temperature and pressure qualifications?
- Which assay methods and conversion assumptions adequately relate atom % D to D2O/HDO/H2O fractions for the grades this catalogue will represent?
- Which application specifications should define supported grades, acceptance limits and requalification triggers?
- Which current jurisdiction-specific sources establish safety classifications, any exposure limits and transfer controls, and how do these differ for unused and reactor-exposed lots?