Abstract
In recent years, there have been large-scale jellyfish outbreaks in the Bohai Sea in summer, which have greatly affected the water intake for cold source of Hongyanhe nuclear power station in Fuzhou bay and threatened the normal operation. This study aims at early warning of invasion of jellyfish, designs and develops acoustic monitoring system for cold source biological (jellyfish)by using ascientificechosounder (EY60,70kHz,Simrad), and carries out real-time monitoring of the echo of cold source biological entering water intake, so as to obtain the resource density of jellyfish from June to September 2019. The acoustic data is processed with a software of Echoview to calculate the average SV and detect the strength of the single target to calculate the daily average flux of the monitoring point. According to the monitoring results, the maximum and minimum daily average values of SV were -62.7dB and -80.0dB, respectively. The maximum and minimum daily average values of target strength are -37.2dB and -81.0dB, respectively. The maximum and minimum daily average values of flux are 5.36ind/(s•m2) and 1.2x10-5ind/(s•m2).Combined with the daily cleaning amount of the monitoring point back-end intercepting network and meteorological data, the comparative analysis is carried out to determine the index level of the acoustic warning for cold source biological flowing into the water intake according to the correlation between average flux and amount of cleaned net.
Highlights
Recirculating cooling water system in coastal nuclear power plants and cooling water supply for other essential equipment are usually set at inshore water intake, and organisms entering the cooling water system from water intake are called cold-source organisms, defense, intercept and disposal of which will have a direct impact on safe and stable operation of the power plant
According to data statistics of American Institute of Nuclear Power Operations (INPO), the number of intake blocking events taking place in global nuclear power plants reached 61 from 2004 to 2008, where nearly 80% of the events led to power reduction of generator set or shutdown, and over 20% of the events directly impacted safety systems of nuclear plants, and invasion of exotic cold-source organisms was the primary cause for intake blocking[1]
Cold source-induced organisms in domestic coastal nuclear power plants mainly include all kinds of jellyfishes, Acetes Chinensis and kelps, etc., especially the influence brought by outbreak of various types of jellyfishes in coastal areas is especially severe in recent years, seriously threatening safety production of coastal nuclear power plants in China
Summary
Recirculating cooling water system in coastal nuclear power plants and cooling water supply for other essential equipment are usually set at inshore water intake, and organisms entering the cooling water system from water intake are called cold-source organisms, defense, intercept and disposal of which will have a direct impact on safe and stable operation of the power plant. Restricted by jellyfish observation and sampling technologies in the monitoring work of jellyfish resources, traditional monitoring work of large-scale jellyfishes mainly relies on netting gear sampling method and visual observation method, and jellyfish distribution and resource variation are investigated through netting gear-based fishing or visual observation results. This method is characterized by unified sampling method and convenient operation, and it can intuitively reflect planar distribution characteristics of large-scale jellyfishes.
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