According to national council on radiation protection and measurements (ncrp) regulations, leakage radiation from the x-ray tube at 1 meter must not exceed

a. 10 gya/h.

b. 10 mgya/min

c. 100 mgya/min

d. 1 mgya/h.

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.