Determining burn-up in spent fuel elements

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

“…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. For americium, since the samples have 241 Am as the major isotope, a spike enriched in the 243 Am isotope is a good option.…”

“…IRMM-1027 Large-Sized Dried (LSD) and LSD spikes produced by the IAEA, prepared from U and Pu metal CRMs, are applied to measure the uranium and plutonium content of dissolved fuels in reprocessing plants. 73,[84][85][86] LSD spike vials have certied masses of uranium ( 235 U and 238 U) and 239 Pu and isotopic composition with associated uncertainty. The main advantage is that they are to be used on an undiluted sample solution containing mg amounts of U and Pu.…”

“…Plutonium. Plutonium isotopes are produced in nuclear reactors through successive neutron captures: 239 Pu by capture of a neutron by a 238 U nuclei, 240 Pu by capture of a neutron by a 239 Pu nuclei, etc. The most common plutonium isotopes measured in environmental samples by ID-MS are 239 Pu, 240 Pu, 241 Pu and 242 Pu.…”

“…show signicant differences. For example, the 240 Pu/ 239 Pu and 241 Pu/ 239 Pu atomic ratios of the global fallout of atmospheric nuclear weapons tests are respectively 0.182 and 9.7 × 10 −4 , 168 whereas the ratio of 240 Pu/ 239 Pu in environmental samples from nuclear weapons test sites at the atolls of Mururoa is 0.018 ± 0.005 (at./at. ±2s).…”

“…In the pressured water reactor using oxide enriched uranium fuel, the isotope ratios of 240 Pu/ 239 Pu and 241 Pu/ 239 Pu are around 0.4 and 0.2 (w t /w t ) respectively, and in MOX fuel the ratios are around 0.9 and 0.4 (w t /w t ) respectively. 170 The 240 Pu/ 239 Pu ratio is the easiest ratio to measure in the environment as 239 Pu and 240 Pu are generally the most abundant isotopes. 241 Pu is a short-lived isotope (t 1/2 = 14.325 years 171 ) whose abundance can be correlated with that of its decay product 241 Am.…”