EXTREME METEOROLOGICAL CONDITIONS

The Level 1 LPS PSA of Mochovce Unit 1 includes as internal events LOCAs, transients and internal hazards, i.e. fires and floods. External events included seismic events, air craft crashes, influences of external industrial facilities, and extreme meteorological conditions. Operational experience and results obtained from PSA for Bohunice V-2 NPP and Dukovany NPP as Mochovce NPP are used as much as possible. 

Extreme meteorological conditions (of temperature, snow, hail, frost, subsurface freezing and drought) ... 

Measures should be taken, by testing and/or analysis, to confirm that the facilities provided to reject heat to the UHS still retain their capability under extreme meteorological conditions, particularly if there are long periods when the facilities are not used. These measures would include, for example. 

Natural external events which shall be considered include those which have been identified in site characterization, such as earthquakes, floods, high winds, tornadoes, tsunami (tidal waves) and extreme meteorological conditions. Human induced external events that shall be considered include those that have been identified in site characterization and for which design bases have been derived. The list of these events shall be reassessed for completeness at an early stage of the design process. 

Because of extreme venting conditions assumed, effective stack heights and resultant plumes from both 3- and 5-minute discharge conditions attain heights beyond the micro-meteorological conditions assumed in accepted computation models. It is therefore highly probable there will be considerably further atmospheric dispersion and diffusion of the VCM than predicted in the results shown. That is, the ground level concentration can be expected to be considerably lower than the values shown in Table 6. 

Hot and dry meteorological conditions in summer increase the extent of observed biomass fires. For example, the summer of 2010 was exceptionally warm in Eastern Europe and large parts of Russia. With climate change such extreme events are predicted to increase and by the end of the century heat waves of this magnitude are expected to occur every decade [50]. For European Arctic the transport of smokes from more frequent biomass fires may affect the global climate change. Whether the Arctic is getting warmer or colder because of the smoke events is still under evaluation. 

The period of ice occurrence and extent of ice fields vary considerably in the different winter seasons, depending on meteorological conditions. Although short periods of ice formation with loose floe ice prevail in the outer sea areas, several-month periods with very close ice have occurred as well. Here, as everywhere, experience has shown that an early or late beginning of ice formation does not allow any conclusions as to the later development of the winter season. It is quite possible that a late beginning of ice formation is followed by an ice-rich winter or, vice versa, that an early onset of ice formation is followed by a mild winter. In the outer sea, ice has to be expected from mid-February. In extreme ice seasons, maximally 60-90 days of ice are observed. In outer sea areas, the last ice after a severe ice season does not melt until early May normally this date is 1 month earlier. 

Many investigations made by Romanian scientists are dedicated to the interrelations between chemical reactions in the atmosphere and specific meteorological conditions. The National Institute of Meteorology and Hydrology, Bucharest is closely involved in the study of the effects of increasing the CO2 concentration on the extreme temperatures and drought episodes in Europe, as well as ozone depletion related studies. 

The above specified criteria for raw water quality are of an informative character. The final assessment of the suitability of a water source is obtained from laboratory or pilot-plant tests based on corresponding analyses. In the case of a public supply it is necessary to perform long-term tests, particularly under extreme meteorological, hydrological and seasonal conditions. 

The Assumptions Register should contain meteorological information, covering both normal and extreme weather conditions. The information should include ... 

The extreme range of recorded temperatures in England taken from die UK Meteorological Office data is 38.5°C to -26.1°C. These values are bounded by the APIOOO site parameters. The possible impact of extreme temperatures on the safety of the generic design is considered in APIOOO External Hazards Topic Report (Reference 3.2, Section 6.5), which demonstrates that credible extreme temperature conditions would not compromise nuclear safety. 

However, despite these complications, smog chambers have proven extremely useful in studying the chemistiy of photochemical air pollution under controlled conditions in which emissions and meteorology are not complicating factors. While there are some... 

There is a clear difference in needs for the on-line coupling of chemistry transport models and the off-line coupling. For the off-line coupled models it would advantageous to improve the quality of meteorological outputs, especially for fair weather conditions (including calm conditions and a focus on extreme situations). Parameters that can be used directly in off-line coupled models and that are important for processes like rainout should also be readily available. (It is important to remember that the couplings can be done in two directions not only from NWP to atmospheric CTM, but also from atmospheric CTM to NWP, see above). 

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