Nuclear isotope measurement in the Hanford environment

The Pacific Northwest Laboratory (PNL) is located at the federal government's Hanford Site in southeastern Washington State, which was built during World War II as part of the secret Manhattan Project to develop the atomic bomb. Monitoring of the Site itself and surrounding environs for Hanford-related radionuclides has been a routine part of the operations since 1944. One of the most sensitive analytical methods used is thermal ionization mass spectrometry (TIMS) with triple-sector mass spectrometers. Normal geometry instruments have an abundance sensitivity of 10-9 for uranium while the authors' newest Triple-Sector Isotope Mass Spectrometer (TRISM), utilizing a new ion-optical design developed at PNL, has an abundance sensitivity of 10-11. In favorable cases, sensitivity is such that complete isotopic analyses are obtained on total samples in the femtogram range; and minor isotopes in the attogram range are measured