Television – Special applications – Hazardous or inaccessible
Patent
1995-12-05
1998-04-14
Britton, Howard W.
Television
Special applications
Hazardous or inaccessible
H04N 718
Patent
active
057398453
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to arrangements, especially optical imaging arrangements, for use in connection with ionising radiation shielded enclosures.
2. Discussion of Prior Art
The Applicants' prior specification no. GB 2186993A describes an arrangement for optically monitoring such an enclosure, eg an enclosure in which operations are carried out on irradiated nuclear fuel. The arrangement is expensive because of the need to provide extensive shielding around the optical components of the arrangement and the need to provide high precision radiation stable components, the arrangement being integral with the radiation shield of the enclosure.
SUMMARY OF THE INVENTION
According to the present invention in a first aspect there is provided an arrangement for forming an optical image of the interior of an enclosure contained within a radiation shield the enclosure being one in which remote handling operations are carried out on radioactive material for example nuclear fuel material during or after use in a nuclear reactor and the shield having a passage therethrough from an outer end to an inner end at the said enclosure, which arrangement includes at or adjacent to the inner end of the passage optical guiding means for guiding optical radiation from scenes within the enclosure along a path through the said passage, located at or adjacent to the outer end of the passage deflection means for deflecting optical radiation which has been guided along the said path and a photodetector arranged outside the shielded enclosure and outside the radiation shield to receive optical radiation which has been deflected by the deflection means.
The shield may comprise a concrete structure to protect the environment outside the enclosure from harmful radiation, eg .beta.-rays, .gamma.-rays and neutrons, emitted by materials in the enclosure. The passage may be formed through a wall, floor or roof of the concrete structure. The region outside the passage beyond the outer end of the passage may itself be contained within an outer radiation shield in which the deflection means may be enclosed. In such an arrangement, a cover may be provided to enclose the photodetector in order to prevent extraneous light from reaching the photodetector. In an alternative arrangement, the photodetector may also be enclosed within the outer radiation shield. The outer shield may comprise for example a heavy metal-containing material such as a material comprising lead or tungsten which absorbs harmful radiation which has travelled through the said passage. The passage itself may include a liner made of metallic material.
Advantageously, one or more passage diameter reducing elements made of radiation shielding material may be incorporated at suitable points along the passage to limit the amount of harmful radiation travelling through the passage and arriving at the outer radiation shield. The elements may be positioned such that they do not obstruct the path of the optical radiation travelling along the passage.
The optical guiding means may comprise a fixed or movable means. Desirably, it comprises a movable means capable of receiving optical radiation from different selected parts of the interior of the enclosure. The optical guiding means may comprise a reflector which reflects optical radiation along the said path. The reflector may be pivotally mounted and arranged to be tilted in either or both of two dimensions to give pan and tilt whereby optical radiation from a hemispherical region in front of the reflector may be guided along the said path. The reflector may for example comprise a prism. The reflector itself may be housed in an optically transparent containment or cover, eg a dome made of quartz, for example fitted into a receptacle in the passage.
The deflection means may comprise a reflector such as a mirror or prism. The photodetector is located in the path of deflected optical radiation, ie offset relative to the path through the said passage whereby the photodetector is l
REFERENCES:
patent: 3229577 (1966-01-01), Ellinger
patent: 4650634 (1987-03-01), Meuschke
patent: 4876593 (1989-10-01), Bauer
patent: 5028379 (1991-07-01), Faulstich
patent: 5592217 (1997-01-01), Hirvonen
Hansford Stuart
Stead Peter
British Nuclear Fuels PLC
Britton Howard W.
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