The measurement of 36Cl and 129I in concrete wastes

Abstract

A method has been developed for the measurement of chlorine and iodine radionuclides in concrete wastes generated from the decommissioning of nuclear power stations. Sequential oxidation of 129 I and 36 Cl from samples of concrete takes less than 7 h and the method is relatively simple and can be used to reliably determine low levels of 129 I and 36 Cl. Generally, recoveries for the procedure are high (in excess of 70%) and large sample sizes can be tolerated ( ~1-10 g). This paper describes the development of the method and demonstrates a relatively simple, repeatable process for the measurement of 129 I and 36 Cl in concrete wastes. The equipment and the methods used should be available at most reactor sites or nuclear plants.

Determination of 36Cl in biological shield concrete using pyrohydrolysis and liquid scintillation counting

“…Analysis by LSC requires quantitative separation of Cl from the sample and other existing radionuclides. Ashton et al 4 developed a method for the measurement of 36 Cl and 129 I in reactor shield concrete. Both 36 Cl and 129 I were recovered as silver salts after the sample had been partly digested and leached with NaOH and the halides were evolved as halogens by sequential oxidation with HNO 3 and KMnO 4 .…”

Applications of hydrogen as a collision and reaction cell gas for enhanced measurement capability applied to low level stable and radioactive isotope detection using ICP-MS/MS

“…It is a long-lived radionuclide (half-life 3.02(4) Â 10 5 years) and is formed by neutron activation of stable 35 Cl, which is present as an impurity in concrete and other reactor components. 30,31 Chlorine-36 can be measured by liquid scintillation counting (LSC), with detection limits on the order of 10-15 mBq g À1 achievable, equivalent to 8.2-12.3 pg g À1 . 32 The long half-life makes 36 Cl theoretically suitable for ICP-MS measurement, with a higher sample throughput compared to decay counting techniques.…”

“…5,7 In one example, 40 Ar plasma gas was suppressed via a charge transfer reaction with H 2 for measurement of 40 Ca impurities in ultrapure water. 8 This was supported by operating under cold plasma conditions (RF reduced to approximately 600 W compared to approximately 1300 W) to reduce the Ar signal due to its high ionisation energy, with the background equivalent concentration (BEC) calculated (0.041 pg g À1 ) as being two orders of magnitude lower than single quadrupole ICP-MS. Hydrogen has also been used as a reaction gas to measure 31 P in the presence of high 30 Si concentrations in Si wafers. The 31 P signal was shied to 31 P 1 H 4 whilst polyatomic 30 Si 1 H remained on mass.…”

Critical comparison of radiometric and mass spectrometric methods for the determination of radionuclides in environmental, biological and nuclear waste samples

“…The interest in the determination of 36 Cl in nuclear waste results from the long half life of 36 Cl and its high mobility in the environment, while the purpose of determination of 36 Cl in the environmental sample normally focus on the application of this radionuclide as a environmental tracer. 36 Cl is a pure beta particle emitter with a high energy (E max = 708.6 keV, 98.1%), it is therefore mainly measured by beta counting such as LSC [129,130,[136][137][138][139][140][141]. The reported detection limit of LSC for 36 C is 14 mBq using Quantulus TM low level LSC for 50 min counting time [136].…”