The present invention relates to radiation shielding apparatus for a radiation source of a scanning apparatus and relates particularly, but not exclusively, to a shielding apparatus for a radiation source of an underwater scanning apparatus.

Pipe scanning tools exist for scanning underwater pipes and include a source of gamma radiation rotated relative to a pipe to be scanned. A known source apparatus for generating a beam of gamma radiation for such an apparatus has a housing of shielding material such as lead or tungsten alloy containing a gamma ray source such as a Cs 137 source. In use, the source apparatus is mounted to a cradle on a rotary part of the pipe scanning tool and the tool is mounted to a pipe. A retractable part of the shielding of the source apparatus is then retracted by remote control means such as a remotely operated vehicle (ROV) to enable a beam of radiation to penetrate the pipe. After use, the retractable part of the shielding is returned to its initial shielding position by remote control, the tool is recovered to a surface vessel and the source apparatus is dismounted from the tool. Preferred embodiments of the present invention seek to improve the safety of pipe scanning tools.

According to an aspect of the present invention, there is provided a radiation shielding apparatus for a scanning apparatus having a radiation source and drive means for rotating the radiation source relative to an object to be scanned by radiation from the radiation source, the radiation shielding apparatus comprising:- shielding means including at least one shielding member adapted to at least partially attenuate radiation from said radiation source passing through said shielding member; mounting means for removably mounting at least one said shielding member relative to a body of said scanning apparatus such that said shielding member is movable between a first position and a second position thereof; and fixing means for fixing at least one said shielding member in position relative to said radiation source in said first position thereof; wherein at least one said shielding member is arranged such that radiation from said source along at least one direction is caused to penetrate said shielding member in said first position thereof but not in said second position thereof.

By providing at least one shielding member adapted to at least partially attenuate radiation from the radiation source which can be removably mounted relative to a body of the scanning apparatus and fixed in position relative to the radiation source in the first position thereof, wherein radiation from the source along at least one direction is caused to penetrate the shielding member in the first position but not in the second position, this provides the advantage of enabling the radiation source to be safely shielded even if the mechanism for returning the primary shielding of the source to its shielding position should become blocked or jammed. In addition, the shielding member can be arranged such that it is brought into its first (i.e. shielding) position by means of a remotely operated vehicle (ROV), so that shielding of the radiation source can be put in place before the tool incorporating the invention is brought into the vicinity of any personnel. This in turn improves the safety of a pipe scanning apparatus incorporating the invention.

At least one said shielding member may be adapted to pivot relative to a body of the scanning apparatus between said first and second positions thereof. This provides the advantage of enabling the radiation shielding apparatus to be made from fewer moving parts, thereby improving its reliability.

The apparatus may further comprise biasing means for urging at least one said shielding member towards said first position thereof. This provides the advantage of reducing the force and/or energy required to activate the apparatus to place the source in a safe condition.

At least one said shielding member may be releasably attached to said biasing means. This provides the advantage of reducing the number of parts removed from the apparatus when the radiation source is removed with the shielding member attached thereto, thereby reducing the cost and complexity of the apparatus.

The apparatus may further comprise latching means for releasably retaining at least one said shielding member in said second position thereof.

At least one said shielding member may be releasably attached to said latching means.

At least one said shielding member may be adapted to be moved from a said second position thereof to a said first position thereof by remote control.

At least one said shielding member may be adapted to be moved from a said second position thereof to a said first position thereof by means of a remotely operated vehicle.

According to another aspect of the present invention, there is provided a scanning apparatus comprising:- a body for removably supporting a radiation source; drive means for rotating said radiation source relative to an object to be scanned; and a radiation shielding apparatus as defined above.

The apparatus may further comprise a radiation source.

A preferred embodiment of the invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:-

Figure 1 is a perspective view of a rotating part of a scanning apparatus embodying the present invention;

Figure 2 is a perspective view of a radiation source apparatus of Figure 1 with a shielding apparatus embodying the present invention mounted thereto in an open position; Figure 3 is an end view of the radiation source and shielding apparatus of Figure 2;

Figure 4 is a view corresponding to Figure 2 with the shielding apparatus in a closed position thereof;

Figure 5 is an end view of the radiation source and shielding apparatus of Figure 4;

Figure 6 is a perspective view from above of the shielding apparatus of Figures 2 to 5; and Figure 7 is a perspective view from below of the shielding apparatus of Figure 6.

Referring to Figure 1 , a scanning apparatus 30 for scanning undersea pipes has a rotary body 32 adapted to be rotatably attached to a pipe (not shown) to be scanned and having cradle 34 for supporting a gamma radiation source apparatus 35 for directing a beam of radiation into the pipe, and a drive apparatus (not shown) for rotating the source apparatus 35 relative to the pipe to scan the pipe.

Referring to Figures 2 to 7, a radiation shielding apparatus 36 embodying the present invention is mounted to the cradle 34 and is pivotable relative to the cradle about a pivot axis 38. The shielding apparatus 36 has a shielding member 40 of dense gamma ray absorbing material such as tungsten alloy removably mounted to a body 42 by means of bolts 44. A bracket 46 is mounted by means of bolts 48 to the shielding member 40 and has apertures 50 for receiving bolts for securely attaching the shielding member 40 to the radiation source apparatus 35 when in a closed position thereof as shown in Figures 4 and 5.

The shielding apparatus 36 has a latching mechanism (not shown) for retaining the shielding member 40 in its open position as shown in Figures 2 and 3, and biasing means in the form of a spring (not shown) urging the shielding member 40 towards its closed position as shown in Figures 4 and 5. The latching mechanism is releasable by means of a first handle 52 which can be operated by a remotely operated vehicle. A second handle 54 is accessible by a remotely operated vehicle to enable the shielding member 40 to be urged to its closed position if the force of the spring fails to bring the shielding member 40 to its closed position.

In the event of blocking or jamming failure of the mechanism of the radiation source apparatus 35 for returning the primary shielding members 20, 22 to their closed positions, the first handle 52 of the shielding apparatus 36 is activated by means of a remotely operated vehicle to release the latching mechanism so that the shielding member 40 can be urged by the spring to its closed position, where it occupies the position which would otherwise be occupied by the primary shielding members 20, 22 to provide full shielding to the radiation source 6. The shielding member 40 is then fixed in this position by means of bolts inserted through the apertures 50 in bracket 46. The bolts 44 are then removed to release the shielding member 40 from the body 42, and the source apparatus 35 is then released from the cradle 34 with the shielding member 40 firmly attached thereto and can be transported to a safe location for repair. In this manner, shielding can be brought into place by remote control before the source apparatus 35 is brought into the vicinity of any personnel.

It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.