A device for cleaning the accommodating means of the bolts of the cover of the reactor vessel of a nuclear centre, comprising: • Brushing means of the accommodating means of the bolt, which can move upwards and downwards along a vertical shaft; • a suction means of the residue dislodged in the accommodating means of the bolt; • a pair of positioning elements in the accommodating means adjacent to that being cleaned; wherein the device is formed by: • a fixed body; and • a mobile body that can move upwards and downwards along the fixed body; wherein the fixed body is formed by: • a pair of lateral pillars, one located on each side of said fixed body; • a lower body that forms a lower joint support between the pair of lateral pillars, said lower body being divided into two parts joined to each other by means of a central connected joint; • wherein the central connected joint is an annular joint wherein the centre is hollow; wherein the mobile body is formed by: • an upper body that constitutes an upper support that supports the brushing means comprising a rotating cleaning brush; said upper body being divided into two parts joined to each other by means of a central connected joint; • wherein the parts that constitute the upper support are susceptible to angular positioning in accordance with the angular positioning of the parts constituting the lower support; • wherein the mobile body supports the brushing means of the accommodating means of the bolt; wherein a connection shaft of the two parts that form the lower body and a connection shaft of the two parts that form the upper mobile body are coaxial; and wherein the brushing means run through the hollow of the annular connected joint of the lower body, characterised in that each of the parts that constitutes the lower body of the fixed body externally forms, towards the side opposite that of the connection shaft, a fork wherein a positioning pin is located; wherein the positioning pin is integrally supported in a connected support that enables said pin to adopt at least one position where it is located in the accommodating means adjacent to that being cleaned, and in a lifted position; and wherein the fork is provided with a guide or cam that has at least one first vertical portion, at least one second oblique or curved portion, and possibly a third vertical portion, and in that the pin or the support of the pin comprises followers susceptible to sliding on the guide or cam, and in that the connected support is susceptible to lifting and lowering, wherein the upper end of the second oblique or curved portion and the third vertical portion determines a third retracted position of the pin, the retraction of the pin being carried out by folding downwards when the support of said pin is lifted, the folding position of the pin having a single degree of freedom, determined by the lifting position of the connection shaft, which in turn determines a position of the cam follower. • Brushing means of the accommodating means of the bolt, which can move upwards and downwards along a vertical shaft; • a suction means of the residue dislodged in the accommodating means of the bolt; • a pair of positioning elements in the accommodating means adjacent to that being cleaned; • a fixed body; and • a mobile body that can move upwards and downwards along the fixed body; • a pair of lateral pillars, one located on each side of said fixed body; • a lower body that forms a lower joint support between the pair of lateral pillars, said lower body being divided into two parts joined to each other by means of a central connected joint; • wherein the central connected joint is an annular joint wherein the centre is hollow; • an upper body that constitutes an upper support that supports the brushing means comprising a rotating cleaning brush; said upper body being divided into two parts joined to each other by means of a central connected joint; • wherein the parts that constitute the upper support are susceptible to angular positioning in accordance with the angular positioning of the parts constituting the lower support; • wherein the mobile body supports the brushing means of the accommodating means of the bolt; wherein a connection shaft of the two parts that form the lower body and a connection shaft of the two parts that form the upper mobile body are coaxial; and wherein the brushing means run through the hollow of the annular connected joint of the lower body, characterised in that each of the parts that constitutes the lower body of the fixed body externally forms, towards the side opposite that of the connection shaft, a fork wherein a positioning pin is located; wherein the positioning pin is integrally supported in a connected support that enables said pin to adopt at least one position where it is located in the accommodating means adjacent to that being cleaned, and in a lifted position; and wherein the fork is provided with a guide or cam that has at least one first vertical portion, at least one second oblique or curved portion, and possibly a third vertical portion, and in that the pin or the support of the pin comprises followers susceptible to sliding on the guide or cam, and in that the connected support is susceptible to lifting and lowering, wherein the upper end of the second oblique or curved portion and the third vertical portion determines a third retracted position of the pin, the retraction of the pin being carried out by folding downwards when the support of said pin is lifted, the folding position of the pin having a single degree of freedom, determined by the lifting position of the connection shaft, which in turn determines a position of the cam follower.