Model 1925-PR


  • Automated, real-time tritium in water monitor using gas proportional counting
  • Input water is separated into hydrogen gas (tritium) and oxygen via an electrolytic gas separator
  • Sensitivity of 3.7 kBq/L or 0.10 µCi/L
  • Sophisticated pulse shaping and discrimination selects only recognizable tritium decay events, rejecting large amplitude or long duration gamma and cosmic ray effects and system noise
  • No hazardous waste produced or scintillation cocktail required
  • Can be configured for freshwater or seawater


The Model 1925-PR is an automated, real-time low-level tritium in water monitor that utilizes a novel electrolysis method to separate the hydrogen (tritium) from oxygen and measure it using an ultra-sensitive gas proportional detector.  The main advantage of the 1925-PR is that it does not require liquid scintillation counting cocktail nor does it produce hazardous mixed waste that must be carefully stored, transported, and disposed of.

The 1925-PR consists of two heavy-duty floor standing cabinets connected to each other.  The first cabinet is the sample conditioning cabinet and consists of the sample filtration and separation components.  The second cabinet is for measuring the sample and includes the gas proportional detection system.

An electrolytic hydrogen gas separator is used to separate the input water into hydrogen gas (tritium) and oxygen.  The oxygen is diluted and safely released while the hydrogen (tritium) is mixed with P-10 gas and pumped through an ultra-sensitive proportional counting detector.  By utilizing proportional counting technology, the user only has to acquire a compact standard steel tank of proportional gas (8.5 m3 or 300 ft3), which will last for up to two months of continuous operation and is available from a variety of suppliers. The P-10 counting gas is 90% Argon and 10% Methane, and is not toxic or combustible.  The hydrogen is dealt with safely by having the instrument enclosures under negative pressure and diluting the small concentrations of hydrogen gas with P-10 gas.

Measurement via this method achieves same or better low-end sensitivity, without having to deal with LSC fluid and waste.  A second, sealed proportional counter eliminates the effects from external gamma fields and 1” lead shielding around the counter tubes further reduces background gamma and improves the statistical signal to noise ratio to enhance sensitivity.

Includes a water pretreatment and filtration system.  The 1925-PR can be configured to measure either freshwater or seawater.

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