Standard Methods: 7500-3H B: Tritium by Liquid Scintillation Spectrometry
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Official Method Name
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7500-3H B. Liquid Scintillation Spectrometric Method |
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Current Revision
| Standard Methods Online |
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Media
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WATER |
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Instrumentation
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Liquid Scintillation Counting |
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Method Subcategory
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Radiochemical |
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Method Source
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Citation
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Brief Method Summary
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A sample is treated by alkaline permanganate distillation to hold back most quenching materials, as well as radioiodine and radiocarbon. Complete transfer of tritiated water is assured by distillation to near dryness. A subsample of distillate is mixed with scintillation solution and the beta activity is counted on a coincidence-type liquid scintillation spectrometer. The scintillation solution consists of 1,4-dioxane, naphthalene, POPOP, and PPO. The spectrometer is calibrated with standard solutions of tritiated water; then background and unknown samples are prepared and counted alternately, thus nullifying errors that could result from instrument drift or from aging of the scintillation solution. |
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Scope and Application
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Used in the nuclear energy industry. Nuclear reactors and fuel-processing plants are localized sources of tritium because of discharges during normal operation. This industry is expected to become the major source of environmental tritium contamination in the future. Tritium is produced in light-water nuclear reactors by ternary fission, neutron capture in coolant additives, control rods and plates, and activation of deuterium. |
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Applicable Concentration Range
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Interferences
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Sample distillation effectively removes nonvolatile radioactivity and the usual quenching materials. For waters containing volatile organic or radioactive materials, use wet oxidation to remove interference from quenching due to volatile organic material. Distillation at about pH 8.5 holds back volatile radionuclides such as iodides and bicarbonates. Double distillation with an appropriate delay (10 half-lives) between distillations may be required to eliminate interference from volatile daughters of radium isotopes. Some clear-water samples collected near nuclear facilities may be monitored satisfactorily without distillation, especially when the monitoring instrument is capable of discriminating against beta radiation energies higher than those in the tritium range. |
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Quality Control Requirements
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See Section 7020 Quality Assurance/Quality Control. |
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Sample Handling
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Glass container. No preservation. |
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Maximum Holding Time
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1 year |
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Relative Cost
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$201 to $400 |
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Sample Preparation Methods
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