Determination of the balance of the nuclear reactor fuel burn-out process by gamma-spectrometry of fission products III

An isotope dilution mass spectrometry overview: tips and applications for the measurement of radionuclides

“…Indeed, the spike weight does not play a role in eqn (6). 59 It should be noticed that spikes usually contain isotopic impurities (for instance, a 236 U spike usually contains traces of 234 U, 235 U and 238 U isotopes). In many cases, especially for the less abundant isotopes at ultra-trace levels, eqn ( 5) and ( 6) must be modied to include and correct for the contribution of these isotopic impurities.…”

“…The only other isotope of Np with a long half-life is the 236 Np isotope (t 1/2 = 1.55 × 10 5 years 146 ) which might permit the determination of 237 Np by ID-MS. However, 236 Np is not commercially available and its production is difficult. 184,185 If a laboratory happens to have a 236 Np solution, it is possible to create an in-house spike by measuring the 236 Np amount fraction by ID-MS using a commercially available 237 Np material.…”

“…A single (eqn ( 5)) and a double isotope dilution equation (eqn ( 6)) are commonly used in environmental samples for the mass fraction determination of 238 U using a spike enriched in the 236 U isotope and the 230 Th/ 238 U ratio using a spike enriched in the 229 Th and 236 U isotopes. Obviously, these equations can be applied for other target radionuclides by using the appropriate spike and the respective atomic masses.…”

“…-It is better if the spike isotope has no isobaric interference. For uranium, the most common spikes are 233 U, 235 U or 236 U, since the main uranium isotope in most samples is generally 238 U (excluding highly enriched uranium material). For plutonium, 240 Pu, 242 Pu or 244 Pu spike isotopes are commonly used, since 239 Pu is usually the main major isotope in most samples.…”

“…7 Age dating of nuclear materials is also an area of growing interest for safeguards and nuclear forensics purposes. The main radio-chronometers that are subject to analytical developments are 230 Th- 234 U and 231 Pa- 235 U for uranium and 241 Am- 241 Pu, 236 U- 240 Pu and 235 U- 239 Pu for plutonium. [8][9][10][11] The accurate measurement of radionuclides is necessary to decrease the uncertainty of the calculated material age.…”