Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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Retrospective dosimetry study at the RPV of NPP Greifswald unit 1Konheiser, J.; Mittag, S.; Noack, K.; Rindelhardt, U.; Borodkin, G.; Borodkin, P.; Gleisberg, B.
For the first time, trepans from a decommissioned VVER-440 (Greifswald-1) reactor pressure vessel (RPV) have been examined. Activities of a trepan, taken at the RPV weld with the highest fast-neutron load, were measured and estimated on the basis of fluence calculations by the codes TRAMO and DORT. A maximum fluence of 4.05*1019 n/cm2 (E>0.5 MeV) was calculated. The average deviation between the two codes is 2.6 %. Activities resulting from the reaction 93Nb(n,n)93mNb were measured, niobium being a trace element in the RPV steel. Unfortunately, 93mNb is also produced by neutron capture in the alloy component 92Mo, the built-up 93Mo decaying by electron capture. The ratios of calculated to measured (C/E) 93mNb gamma activities for several trepan samples are between 0.42 and 0.97. The fact that all C/E ratios are below unity suggests that the measured values may have been additionally heightened by activities from other nuclides.
Keywords: reactor, retrospective dosimetry, neutron, fluence, VVER-440, TRAMO, Greifswald
13th International Symposium on reactor Dosimetry, 25.-31.05.2008, Alkmaar, Netherlands
Contribution to proceedings
13th International Symposium on Reactor Dosimetry, 25.-31.05.2008, JRC Petten, Netherlands
Reactor Dosimetry State of the Art 2008, New Jersey London Singapore: World Scientific Publishing Co. Pte. Ltd., 13 978-981-4271-10-3, 23-33