To ask the Secretary of State for Defence if scientists from (i) the atomic weapons establishments, (ii) the Blacknest verification centre or (iii) his Department have (a) been given access by the United States Government or weapons development laboratories to data arising from United States nuclear tests in Nevada and (b) been permitted to be present to monitor United States nuclear tests since 1979.

Under the 1958 agreement between the United Kingdom and the United States for co-operation in the uses of atomic energy for mutual defence purposes, such information may be exchanged and joint experiments may be conducted. United Kingdom scientists may be present at the nuclear test site in connection with joint United Kingdom/United States tests for periods of several months.

To ask the Secretary of State for Defence if he will set out in the Official Report the proportion of overall costs of the United Kingdom nuclear testing programme that is made up by (a) research, design and development, (b) nuclear testing and (c) deployment and storage.

It would not be in the national interest to reveal such details of the United Kingdom's nuclear testing programme.

To ask the Secretary of State for Defence what proportion of nuclear warhead tests conducted by or on behalf of the United Kingdom in Nevada since 1979 were undertaken to check the safety and reliability of the warheads.

Such tests are carried out in order to maintain the effectiveness of the United Kingdom's nuclear weapons capability and it is not our practice to comment on specific aspects.

To ask the Secretary of State for Defence what is the total radioactive inventory that has been vented to the atmosphere from United Kingdom nuclear explosive tests conducted underground at the Nevada test site since 1963; and whether his Department has conducted any survey on the potential adverse health effects posed by such releases of airborne radioactivity.

The total radioactive inventory released from United Kingdom underground tests at the Nevada test site amounts to less than 100 Curies—3·7 terabecquerels—and consisted of short-lived gaseous isotopes. No releases were of any health or environmental consequence on site or off site.