Construction layout for underground caverns in nuclear island powerhouse of underground nuclear power plant

A construction layout for underground caverns in a nuclear island powerhouse of an underground nuclear power plant, the construction layout comprising:

• a) two primary caverns accomodating nuclear reactor powerhouses;
• b) combined caverns;
• c) electric powerhouse caverns;
• d) pressure relief caverns;
• e) a first primary traffic tunnel;
• f) a second primary traffic tunnel;
• g) a third primary traffic tunnel;
• h) a top adit system;
• i) a ground adit system;
• j) secondary traffic tunnels;
• and
• k) a side traffic tunnel;
• wherein
• a connecting line of medial axes of the two primary caverns accomodating nuclear reactor powerhouses is perpendicular to a longitudinal direction of a mountain;
• each combined cavern and each electric powerhouse cavern are disposed at two sides of each primary cavern, respectively;
• two combined caverns are in end-to-end connection and an arrangement direction of the two combined caverns are in parallel to the connecting line of the medial axes of the two primary caverns;
• each pressure relief cavern is disposed between each combined cavern and a corresponding electric powerhouse cavern;
• outer sides of caverns in the two combined caverns are connected to a side traffic tunnel disposed outside the two combined caverns via the secondary traffic tunnels;
• two ends of the side traffic tunnel are connected to the first primary traffic tunnel and the third primary traffic tunnel arranged in the longitudinal direction of the mountain;
• the first primary traffic tunnel and the third primary traffic tunnel are disposed outside two end faces of the two combined caverns, respectively;
• the second primary traffic tunnel is arranged in the longitudinal direction of the mountain between the first primary traffic tunnel and the third primary traffic tunnel and is connected to a middle part of the two connected combined caverns;
• each of the first primary traffic tunnel, the second primary traffic tunnel, and the third primary traffic tunnel communicates with a ground surface;
• the two primary caverns, the combined caverns, the electric powerhouse caverns and the pressure relief caverns form a cavern group of the nuclear island powerhouse of the underground nuclear power plant;
• and
• a skewback or an endwall of an arch crown of each cavern of the cavern group communicates with the ground surface via the top adit system;
• and a bottom of a sidewall or a bottom of an endwall of each cavern of the cavern group communicates with the first primary traffic tunnel, the second primary traffic tunnel, and the third primary traffic tunnel via the ground adit system.