(NU/1820) Decommissioning of the Gammacell 1000 Elite and Disposal of Sealed Sources

Description

The University seeks a contractor to decommission the irradiator described in Section 2.2 of the ITT, the disposal or recycling of the associated HASS of Cs-137 described in Section 2.3.2 of the ITT, and the disposal or recycling of other sealed sources described in Section 2.3.3. In this respect, the University expects the contractor to remove of the irradiator and the HASS from the University site and take full ownership and responsibility of the HASS thereafter. Similarly, the contractor is expected to remove and take full ownership and responsibility of all sealed sources listed in Appendix 1. The University has a gamma irradiator that was procured in 1994 for various applications in the field of biological sciences. With the advent of x-ray irradiators becoming more effective and flexible, they are now more popular and affordable alternatives than gamma irradiators. Indeed, coupled with inherently lower radiation risks and better safety profiles, several governments around the world, including the UK, have been encouraging the replacement of gamma irradiators with x-ray irradiators. The model of the gamma irradiator is Gammacell 1000 Elite, identified by the serial number 259, and was manufactured by Nordion International Inc. The irradiator was procured by the University in February 1994, and a copy of the Certificate of Measurement is available if required. The irradiator comprises a fire-resistant plastic cabinet surrounding a steel frame, on which a stator and rotor sit. The dimensions of the irradiator are 84 cm wide by 81 cm deep and 160 cm high. It is anticipated that the whole irradiator unit weighs over 1100 kg. The stator contains the radiation source, and the rotor contains the sample chamber. From the control panel, a direct current can be applied to the rotor to rotate the sample chamber into the radiation field in the stator for a prescribed time and return to the “load/unload” position. Access to the sample chamber is gained by opening a door in the cabinet. However, an interlock system prevents operation of the unit when the door is open. A battery backup has been added, which in the event of power lost will return the rotor to the “load/unload” position. Both the rotor and stator are made from lead alloy encased in steel jackets, which also act as the radiation shields. Measured external radiation dose rates in the operating condition showed no greater than 10 µSv/h at 10 cm from the accessible surfaces of the unit. Dose rate measurements are carried out every 6 months. The irradiator is located within the University’s Medical School in a secure ground floor room. The full address can be provided to the contractor. The entirety of the irradiator, including the electrical component of the rotor and stator, as well as the HASS, is to be considered in this tender for decommissioning.

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