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rays irradiation, 3; Effects on depth of localized corrosionNakano, Junichi; Tsukada, Takashi; Ueno, Fumiyoshi; Yamagata, Ryohei
no journal, ,
In the Fukushima Daiichi Nuclear Power Station, it is considered that corrosion of primary containment vessel (PCV) and reactor pressure vessel (RPV) steels is accelerated by seawater injection and high radiation dose. In general, it is known that weight loss in steels increases near gas-liquid interface. Therefore, the lower half of the specimens was dipped in diluted seawater at 50
C under rays irradiation. Gas phase in flasks was air or N
atmosphere. After the tests, oxide layer was removed and 3 dimension (3D) digital data were measured on the specimen surface using a 3D macro-scope. In air atmosphere, the maximum roughness height increased with time and dose rate. After rays irradiation for 500 h, the maximum roughness height in N atmosphere was lower than that in air atmosphere. Since O concentration in liquid was reduced by decrease of O partial pressure in gas phase, it was appeared that localized corrosion was suppressed.
Nakano, Junichi
no journal, ,
Seawater was injected into the reactor cores in the Fukushima Daiichi Nuclear Power Station (1F-NPP). Radiation dose is high in the primary containment vessels (PCVs) because of the fuel debris and the fission products. It is considered that corrosion of the reactor pressure vessels and the PCVs is accelerated by the products of water radiolysis. An amount of the injected seawater, temperature, radiation dose in the PCVs of the 1F-NPP and decommissioning plan are shown. Corrosion tests of low alloy steel and carbon steel under -rays irradiation conducted in the Japan Atomic Energy Agency are introduced. Uniform corrosion rates of the steels were hard to be accelerated remarkably in dose levels which were measured in the PCV of the 1F. Moreover, as a way of corrosion prevention, it was effective to have replaced the gaseous phase with N.
Tsukada, Takashi; Kita, Satoshi; Ueno, Fumiyoshi
no journal, ,
Corrosion behavior of steel materials such as mild steel or low alloy steel in water environment has been examined by corrosion tests immersing specimens statically to test solution. However, in the actual plant environment, conditions of water flow or alternating exposure to water/air are dynamically affecting the corrosion behavior. In this study, therefore, corrosion tests by rotating flat-type specimens in the diluted seawater/air environment were performed and effects of water flow and alternating exposure on corrosion of the steels were examined. Results of the rotating corrosion tests in 200 times diluted seawater saturated with dissolved oxygen at 30C for 500 hours will be presented and discussed in the presentation.