Defrosting

Abstract

An apparatus comprising a cooling chamber comprising a cooling unit for cooling uranium hexafluoride in the chamber; and a heater comprising a first region inside the cooling chamber arranged to defrost the cooling unit; and a second region outside the cooling chamber arranged to receive heating fluid cooled in the first region and to heat the received fluid. A method of defrosting a cooling unit is also described.

1 . An apparatus of a uranium hexafluoride take-off unit comprising:
 a uranium hexafluoride cooling chamber configured to receive a uranium hexafluoride container, the chamber comprising a cooling unit for cooling the uranium hexafluoride in the chamber; and   a heater comprising a first region inside the cooling chamber arranged to defrost the cooling unit; and a second region outside the cooling chamber arranged to receive heating fluid cooled in the first region and to heat the received fluid, wherein the second region of the heater is configured to heat the fluid cooled in the first region by exposing the fluid to an ambient temperature fluid outside the cooling chamber.   
     
     
         2 . An apparatus according to  claim 1 , wherein the first region of the heater is arranged to receive fluid heated in the second region of the heater. 
     
     
         3 . An apparatus according to  claim 1 , wherein the first region of the heater is configured to heat the cooling unit by exposing the cooling unit to a first region of heating fluid conduit containing fluid heated in the second region of the heater. 
     
     
         4 . An apparatus according to  claim 1 , wherein the ambient temperature is between approximately fifteen and thirty degrees Celsius. 
     
     
         5 . An apparatus according to  claim 1 , wherein the second region of the heater comprises a heat exchanger configured to move ambient temperature fluid outside the cooling chamber over the second region of the heater. 
     
     
         6 . An apparatus according to  claim 1 , wherein the ambient temperature fluid outside the cooling chamber is atmospheric air. 
     
     
         7 . An apparatus according to  claim 1 , wherein the heater comprises a heating fluid circuit comprising said first and second regions. 
     
     
         8 . An apparatus according to  claim 3 , wherein the second region of the heater comprises a second region of heating fluid conduit which is exposed to ambient temperature fluid outside the cooling chamber and is arranged to receive the fluid cooled in the first region of the heater. 
     
     
         9 . An apparatus according to  claim 8 , wherein the second region of heating fluid conduit comprises one or more heat exchange elements to increase the effective surface area of the second region of conduit which is exposed to the ambient temperature fluid outside the cooling chamber. 
     
     
         10 . An apparatus according to  claim 1 , wherein the cooling unit comprises a cooling evaporator configured to evaporate a fluid coolant. 
     
     
         11 . An apparatus according to  claim 1 , wherein the cooling unit is configured to cool the chamber to a temperature of below zero degrees Celsius. 
     
     
         12 . A uranium hexafluoride take-off unit comprising an apparatus according to  claim 1 . 
     
     
         13 . An apparatus for defrosting a cooling unit in a uranium hexafluoride cooling chamber, comprising:
 a first heat exchanger configured to heat the cooling unit by exposing the cooling unit to a first region of heating fluid conduit inside the cooling chamber; and   a second heat exchanger configured to expose a second region of the heating fluid conduit to an ambient temperature outside the cooling chamber to heat heating fluid inside the conduit.   
     
     
         14 . An apparatus according to  claim 13 , wherein the first region of heating fluid conduit is connected to the second region of heating fluid conduit so that the heating fluid flows between the first and second regions of conduit. 
     
     
         15 . A method of defrosting a cooling unit in a uranium hexafluoride cooling chamber of a uranium hexafluoride take-off unit, comprising:
 causing a heating fluid to flow into the cooling chamber;   causing the heating fluid to heat the cooling unit in the cooling chamber, thereby cooling the heating fluid;   causing the heating fluid to flow out of the cooling chamber; and   causing the heating fluid to be heated outside the cooling chamber by exposing the heating fluid to an ambient temperature outside the cooling chamber.   
     
     
         16 . A method according to  claim 15 , wherein exposing the heating fluid to the ambient temperature comprises exposing the heating fluid to an ambient temperature fluid outside the cooling chamber. 
     
     
         17 . A method according to  claim 15 , wherein the ambient temperature fluid is gas or liquid under atmospheric conditions.