HC Deb 25 February 1981 vol 999 cc387-8W
Mr. Ernie Ross

asked the Secretary of State for Defence what is his estimate of the radius and depth of the crater that would be created by a 1 megaton device blasted on the ground.

Mr. Goodhart

For representative geology, it is estimated that a one megaton explosion at ground level would produce a crater approximately 900 ft in diameter and 200 ft deep.

Mr. Ernie Ross

asked the Secretary of State for Defence what are the radioactive half-lives of the principal components in nuclear blast fall-out.

Mr. Goodhart

Nuclear fall-out contains many radioactive isotopes. Most of these have half-lives of less than one day. Of the longer lived isotopes, three of the most important biologically are iodine-131, strontium-90 and caesium-137 whose half-lives are eight days, 27.7 years and 30.0 years respectively.

Mr. Ernie Ross

asked the Secretary of State for Defence what is his estimate of the destructive force of a 1 megaton nuclear device upon buildings within a 5-mile radius from the centre of the blast.

Mr. Goodhart

For a 1 megaton surface burst, in typical atmospheric conditions, reinforced concrete buildings would be destroyed to a radius of about 1 mile and severely damaged to about 1½ miles, brick buildings would be destroyed and severely damaged to radii of about 3 and 4 miles respectively.

Mr. Ernie Ross

asked the Secretary of State for Defence what is his estimate of (a) blast deaths and (b) severe casualties in the following radii from the centre of a 1 megaton nuclear device (i) 2 miles and (ii) 5 miles.

Mr. Goodhart

It is estimated that up to 90 per cent. of the population would be killed within 2 miles of a 1 megaton surface burst and a further 5 per cent. would be severely injured; at distances between 2 and 5 miles, up to 40 per cent. would be killed and 20 per cent. severely injured.

Mr. Ernie Ross

asked the Secretary of State for Defence what is his estimate of the wind speeds that would be induced within a 5-mile radius from the centre of a 1 megaton nuclear device.

Mr. Goodhart

A 1 megaton surface burst in typical atmospheric conditions would produce maximum wind velocities of about 200 and 60 miles per hour at 2 and 5 miles respectively, although the winds would decrease to small fractions of these speeds in a few seconds.

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