Bulletin Number Two 1984

While site emergency can be controlled w ith relative ease, a public emergency would be a serious problem to solve. S.L Hsu: Two-thirds o f the total energy produced by a nuclear reactor are usually wasted, leaving one-third for power generation. The large amount o f waste heat is normally discharged through air or water. From the geographical position and climatic condition o f Daya Bay nuclear plant, it is estimated that it w ill install an once-through water cooling system —large quantity o f sea water is pumped into the condenser and after absorbing the heat is discharged into the sea. The fact that Daya Bay is an enclosed bay makes water exchange w ith the surrounding areas difficu lt. The sea temperature w ithin a few kilometres o f the plant w ill o f course be raised noticeably. This w ill have considerable effect on the ecology there. The rising o f the sea surface temperature w ill result in frequent fog, especially in winter. The saturation point o f cold air is lowered and the warm sea surface w ill provide adequate vapour for the formation o f fog. Foggy weather w ill affect sea trans­ portation. The authorities concerned should therefore study thoroughly and get a fu ll picture o f the degree o f these impacts before setting up the plant. As for the suspended particulates and the radio active substances discharged by the plant, it is less threatening because it is about fifty kilometres away from Hong Kong and much o f them w ill be dispersed before reaching Hong Kong. Hong Kong w ill only be affected by these pollutants in winter when the north east monsoon blows but in summer when the south west monsoon prevails, it w ill be free from such threats. The downwind concentration o f air-borne particulates can be estimated by the Gaussian Dispersion Equation. In light wind conditions and stable atmospheres, they are not easily dispersed, leading to high downwind concentration. In strong wind condition and unstable atmospheres, effective dilution and dispersion lead to low downwind con­ centration. From the wind-rose o f the Hong Kong Royal Observatory, we know that east wind prevails in Hong Kong for about 40% o f the time in a year, east north­ east for 10%, north northeast for 8%. The east and northeast wind predominating for over half a year is also the wind direction that emissions from the Daya Plant w ill have the greatest impact on the health o f Hong Kong citizens. In choosing the site o f the plant and planning the exhaust system, the authorities con cerned should take into consideration the undesirable effects certain wind directions and water current w ill have on the residents in the downwind area. P. Kw o ng : We should seriously contemplate the impact of the Daya nuclear power plant on the University, Shatin and Tai Po. From the map ， we can see that although the nuclear plant is about fifty kilometres from Central, w ith the Lion Rock and Ma On Shan in between, it is only th irty odd kilometres northeast of this University. The only sight barrier to the plant are just low-lying hills o f about two hundred metres. Since east and northeast wind prevails in Hong Kong over 50% o f the time in a year, the University w ill bear the brunt o f the diffusion o f radioactive material from the nuclear plant. The University, Shatin and Tai Po are sur rounded by hills except in the northeast, so radio active materials carried by wind and precipitations w ill be 'bottled' in. Given the terrain o f the area, their diffusion out o f the Valley' w ill probably be slow, thereby increasing the likelihood o f their settling down in the area, for example into the Plover Cove Reservoir. The combined population o f Shatin and Tai Po w ill be over one m illion w ithin the next ten years. They w ill be two densely populated new towns. Con sidering the factors mentioned so far, we conclude that o f all districts in Hong Kong, Shatin and Tai Po w ill be the two most threatened areas by radiation from the plant. However, a definite statement on this matter cannot be made without thorough research into questions like the radioactivity and the diffusion pathways o f normal and accidental releases/leakages. Daya nuclear plant is by no means small (in fact, it is almost the same size as the one at Three Miles Island), therefore it is necessary to study thoroughly and solve the following problems before launching the project: (1) the disposal o f nuclear waste; (2) dispersal o f the population o f Shatin and Tai Po in case