First direct determination of the ⁹³Mo half-life

Area of Science:

• Nuclear Physics
• Radiochemistry
• Analytical Chemistry

Background:

• Accurate nuclear decay data is crucial for nuclear facility safety and waste management.
• Previous estimations of the ⁹³Mo half-life had significant uncertainties.
• ⁹³Mo is a man-made radionuclide found in nuclear waste.

Purpose of the Study:

• To perform the first direct measurement of the ⁹³Mo half-life.
• To improve the precision of the ⁹³Mo half-life determination.
• To accurately determine the decay probability of ⁹³Mo to ^93mNb.

Main Methods:

• High-resolution mass spectrometry for ⁹³Mo concentration determination.
• Liquid scintillation counting for specific activity measurement.
• Chemical separation of molybdenum from proton-irradiated niobium with high decontamination factors.

Main Results:

• The ⁹³Mo half-life was measured as 4839(63) years, over 20% longer than the adopted value.
• The relative uncertainty of the half-life was reduced by a factor of 15.
• The probability of ⁹³Mo decay to ^93mNb was determined to be 95.7(16)%, with 8 times greater precision.

Conclusions:

• The new ⁹³Mo half-life value necessitates updates in nuclear decay data.
• Improved modeling of low-level nuclear waste composition is now possible.
• The study highlights the importance of advanced chemical separation and analytical techniques for nuclear data precision.