Standard No.:	HAD 101/10-1991
English Name:	Extreme Meteorological Events in Nuclear Power Plant Siting (Excluding Tropical Cyclone)
Chinese Name:	核电厂厂址选择的极端气象事件(不包括热带气旋)
Professional Classification:	HAD    Professional Standard - Nuclear Power
Issued by:	the National Nuclear Safety Administration
Issued on:	1991-04-26
Implemented on:	1991-4-26
Status:	valid
Language:	English
File Format:	PDF
Word Count:	20000 words
Price(USD):	400.0
Delivery:	via email in 1 business day

1.1 General Provisions This guideline is description and supplement to relevant articles of "Safety Regulation for Nuclear Power Plant Siting" (HAF 101, hereinafter referred to as the "Regulation"). This guideline is a guideline document, and methods and proposals beyond this guideline may be adopted in real work, but it must be proven to the National Nuclear Safety Administration that the methods and proposals adopted have the same safety level as those in this guideline and will not cause unacceptable risk to the nuclear power plant staff and the public. Atmosphere is a very complex system. In order to assess its influence on the nuclear power plant, the atmosphere may be characterized approximately by such meteorological parameters as wind speed, air temperature, precipitation, humidity, etc.. Among these parameters, some may reach to the value being significant to the safety and shall be considered in the design through determining appropriate design basis. These values may be get from conventional meteorological observation or through analysis on infrequent events e.g. tornado or cyclone. This guideline provides methods both to determine the extreme values of meteorological parameters (e.g. wind speed and air temperature) and to determine the design basis events of specific meteorological events (e.g. tornado). In this guideline, the practice determining the extreme value of individual rare event has been extended to determine the extreme value of parameters serving as continuous time function; thus, to determine the extreme value of the time sequence, the time sequence is treated as an event with the design basis to be determined. In this guideline, the determination of design basis follows the procedures recommended in the "Regulation". 1.2 Scope According to the general criteria of the "Regulation", this guideline discusses the extreme value of meteorological parameters and the extreme meteorological events. And the procedure is outlined according to the following steps. (1) Discuss and classify the meteorological events and parameters according to their influence on safety. (2) Select data source and collect data. (3) Analyze meteorological parameters (e.g. air temperature) to determine their design basis; select the design basis event of meteorological events (e.g., design basis tornado). (4) Determine the design basis values of meteorological parameters or the design basis of meteorological events (e.g., the pressure drop and maximum wind speed of design basis tornado). The following chapters outline the general evaluation procedures of the design basis of extreme meteorological parameters and events, and then detail the evaluation procedures of each kind of considered parameter or event. Parameters involved in this guideline to characterize the meteorological environment include wind speed, atmospheric precipitation amount and temperature. The extreme meteorological event discussed here is tornado, and tropical cyclone is also discussed briefly. The tropical cyclone is discussed more extensively in the Safety Guideline of "Design Basis Tropical Cyclone for Nuclear Power Plant" (HAD 101/11). Extreme meteorological events and parameters which are not discussed in this guideline but may be necessary to be assessed for design basis include such events as snowstorm, dust storm, drought and lightning; such parameters as ice layer, frost, fog and hailstone. 1.3 Design basis of extreme meteorological parameters and events The design basis shall be derived from the extreme values of meteorological parameters and from the parameter values of extreme meteorological events with low enough exceedance probability. As for every condition, evaluation shall be conducted from the aspect of safety.