Retrospective dosimetry

Materials for ESR Dosimetry and Dating. Materials used for retrospective dosimetry of radiation exposure depend on the situation. In addition to human tooth enamel, materials worn by the person, such as shell buttons, or used nearby at the site, such as sugar,32 have been studied to evaluate the radiation dose. On the other hand, materials for ESR radiation dosimetry elements should be well-controlled synthetic chemicals, although natural materials like bovine bones and sugar were proposed in the past. 

Approximate axial g-tensors are frequently observed for transition metal ion complexes. Inorganic radicals can also have appreciable axial g-anisotropy. This property is of value for the assignment of ESR powder spectra in applied studies. Carbon dioxide radical anions, CO2, and related species contribute for instance to the ESR signal used for geological dating [21] see Chapter 9. The ESR spectrum of this anion has also been employed as an indicator that a certain foodstuff has been irradiated, for dosimetric purposes in certain carboxylic acid salts, and as a component in tooth enamel samples used in retrospective dosimetry. 

Within FP-5 project RETROSPEC work will be done to improve the evaluation of the neutron doses induced in reactor structural materials in those cases where no or unreliable data from surveillance specimens are available (for example the older generation of WWER-440 type reactors). The objectives of this project are to develop procedures and guidelines for retrospective dosimetry which are independent of the type of steel and of the time elapsed after removing the material from the reactor. 

The stabilised austenitic stainless steels for cladding contain an alloying element (niobium), which forms stable grain boundary carbides. This prevents chromium depletion along the grain boundaries and makes the material immune to stress corrosion cracking. Non-stabilised material was used for the first layer because the thermal expansion coefficient of the material is closer to that of the low-alloy pressure vessel material. The presence of niobium in the second layer allows performance of so-called retrospective dosimetry in the RPV inner surface by machining out some scraps for further chemical separation and activity measurement to determine real neutron fluence on the RPV inner surface. 

Jain M, B0tter-Jensen L, Murray AS, Jungner H (2002) Retrospective dosimetry dose evaluation using unheated and heated quartz from a radioactive waste storage building. Radiat Prot Dosim 101(l-4) 525-530... 

Ainsbury, E.A., Bakhanova, E., Barquinero, J.F., et al., 2011. Review of retrospective dosimetry techniques for external ionising radiation exposures. Radiat. Prot. Dosim. 147 (4), 573-592. 

Epidemiological and Human Dosimetry Studies. Retrospective epidemiological studies on small groups of individuals revealed an increased incidence of gastrointestinal symptoms, dark urine, and skin effects associated with drinking water contaminated with phenol (Baker et al. 1978 Kim et al. 1994). 

Radiation Personnel Accident. Radiation exposure in accidents of personnel in nuclear facilities and non-destructive detection have been evaluated with ESR dosimetry. For example, the amputated medium fibre bone of a worker in Peru, who tried to solve the problem by directly touching the source of 60Co unit for a few seconds, was measured four years later.The dose was measured by 6.4 + 0.5 Gy, while 20 + 3 Gy was obtained from fluorescence in situ hybridization method. The result would suggest diagenic decay of the signal due to the metabolism of bone.96 Thus, ESR gives the retrospective dose for radiation accidents. 

Kleinerman, R. A., Romanyukha, A. A., Schauer, D. A., and Tucker, J. D. (2006). Retrospective assessment of radiation exposure using biological dosimetry Chromosome painting, electron paramagnetic resonance and the glycophorin a mutation assay. Radiat Res 166, 287-302. 

---