TNAG-1506-FCO40-2064-Guangdong-nuclear-power-station-project-at-Daya-Bay-safety-c-1986 — Page 159

D1.DWP13

Hong Kong PWR Assessment

External Hazards Questions

The questions are of two types. Firstly, there is a need for site specific/regional information on the occurrence of extreme events, both natural and man made, in order to make an estimate of the site hazard for each hazard of interest or concern. Secondly, there is a need for design specific information about the means by which protection is provided to reduce the threat posed by external hazards, in order to gauge the residual risk due to external hazards beyond the design basis. These two needs

These lists are not are detailed below for each hazard. comprehensive since the questions of relevance cannot be judged they do without fairly detailed knowledge of local conditions;

They also represent a represent a reasonable first stage. substantial request in that complete answers to all the questions

I have would take a significant amount of time and resource. therefore excluded several potential external hazards (such as volcanic activity) which seem to be of less concern at this stage.

1 a Earthquakes Siting

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Soil conditions (type and depth to bedrock) at the site. Known local active or dormant seismically capable features Local topography and nearby potentially unstable slopes

Site investigation results

Regional historical observations of earthquake intensities and effects within 100 Km of the site (over as long a timescale as possible)

Instrumental records of earthquakes and seismicity within 200 Km of the site (mainly 20th century)

"Seismo-tectonic", structural geology and seismic source zone interpretations for structures and mechanisms currently influencing regional seismicity

1 b

Earthquakes Design

The level and exceedence frequency of the Safe Shutdown Earthquake and Operating Basis Earthquake

The design codes and standards used for structural and component seismic qualification

Any significant design departures (from the usual French 900 MWe PWR design) which influence aseismic protection (either to achieve an enhancement or, perhaps unintentionally, to produce some degradation).