Highlights of the OECD LOFT LP-FP-2 experiment including hydrogen generation, fission product chemistry, and transient fission product release fractions.

摘要

The purpose of this paper is to present the primary highlights of the OECD LOFT Experiment LP-FP-2. These highlights include the chemistry of the released fission products, the transient fission product release fractions, and the total amount and distribution of hydrogen generated during the experiment. As determined from the upper plenum coupon data, it is concluded that CsI was not present in significant concentrations during the experiment. Instead, AgI and CsOH appear to have been the primary fission product species for I and Cs. Based on the blowdown suppression tank (BST) data and the on-line gamma spectrometer data, the transient releases of volatile fission products ranged from 2% to 5% of the initial center fuel module (CFM) inventory. However, the major release of volatile fission products occurred during reflood and amounted to an additional release of 9% to 14%. The primary reason for the small transient release fractions was the initially large grain structure of the fuel ((approximately)14 (mu)m) and the smaller than expected peak transient fuel temperatures (2300 K to 2700 K). The amount of hydrogen gas measured in the BST was 205 (plus minus) 11 g, and the amount estimated in noncondensable bubbles in the primary coolant system (PCS) was 819 (plus minus) 364 g. Thus, the total amount of hydrogen released during LP-FP-2 was 1024 (plus minus) 364 g. This quantity of hydrogen is equivalent to an oxidation of 58% of the initial zircaloy mass. Since most of the hydrogen generated during the transient should have been transported to the BST, it appears that the large amount of hydrogen observed in the PCS was generated after the PCS was isolated; that is, following reflood. 4 refs., 15 figs., 3 tabs. (ERA citation 15:032346)