council decis april approv conclus commiss protocol kingdom sweden swiss confeder amend cooper agreement field control thermonuclear fusion plasma physic euratom council european commun regard treati establish european atom energi commun paragraph articl thereof regard draft submit commiss commiss accord direct council negoti protocol amend cooper agreement sweden switzerland field control thermonuclear fusion plasma physic advis approv conclus commiss protocol decid sole articl conclus commiss protocol kingdom sweden swiss confeder amend cooper agreement field control thermonuclear fusion plasma physic approv text protocol attach decis luxembourg april council presid tindeman