Patent Number: 
Section: abstract

The present invention relates to a fuel rod for a nuclear plant and a plenum spring arranged to be provided in a fuel rod. The fuel rod (1) comprises a cladding tube (2) sealed at its ends by end plugs (3, 4), a plurality of fuel pellets (5) stacked on each other inside the cladding tube (2) such that they form a column of pellets and said plenum spring (6) arranged to hold with a spring force the column of pellets against the lower second end of the cladding tube (2) during operation. The plenum spring (6) comprises a first length variable part (8) which abuts the uppermost located fuel pellet (5) in the column of pellets with an end portion (9), a second part (10) which allows engagement of the plenum spring (6) against an inner surface of the cladding tube (2) by a radially outwardly directed pressure and a third part (11) which allows releasing of the second part (10) of the plenum spring (6) in the cladding tube (2) during operation of the nuclear plant.