Silicon-32

Physical Characteristics

  • Half-life: 104 years
  • Emissions: Beta particles with a maximum energy of 0.224 MeV and an average energy of 0.067 MeV. Since Si-32 decays to P-32, emissions from a Si-32 source also include the 1.71 MeV beta from P-32
  • Maximum Range: 37 cm in air; <.05 cm in tissue.
  • See the P-32 fact sheet for information about the properties of the beta from the P-32 progeny.

Dose Rate and Shielding

  • Dose rate to the skin at 10 cm: See the P-32 fact sheet for information about the dose from the P-32 progeny.
  • Dose rate to epidermal basal cells from skin contamination of 1 µCi/cm2: See the P-32 fact sheet for information about the dose from the P-32 progeny.
  • Shielding: Depending on the age of the material, plexiglas shielding may be required for the P-32 progeny.
  • Annual Limit on Intake (ALI): 2000 microcuries via ingestion and 200 microcuries via inhalation. The intake of one ALI will produce a dose of 5 rem.

Detection

A G-M detector will readily detect low-level P-32 contamination, although wipe surveys using liquid scintillation counting is also an acceptable method for detecting removable P-32 contamination.

Precautions

High localized doses are possible while handling millicurie amounts of P-32 and as a result of skin contamination. Reduce doses by wearing safety glasses (for shielding the eyes), using remote handling tools such as tongs, using shielding extensively to shield storage and experimental containers and work areas, and performing thorough and frequent surveys of the work area, clothing and the body.

Waste Disposal

  • Solid Wastes: through the Onsite Decay-in-Storage Program
  • Liquid Scintillation Wastes:  through the Off-Site Radioactive Waste Disposal Program
  • Liquid Wastes: through the Sewer Disposal Program. The laboratory disposal limit for P-32 is 0.3 mCi per month.