Waste that may contain radioactive substances shall be measured on the facilities using, for example, the Puck method or another method of similar reliability.
As a general rule, a sample must be taken from each barrel of waste. Mixed samples can be taken of radioactive waste coming from the same physical object. If mixed samples are taken, a subsample must be taken from each of the barrels that the mixed sample represents. The subsamples from the individual barrels shall be of the same size and of at least 100 ml. The subsamples from the barrels must be taken as soon as the individual barrels are filled up.
Samples shall be analysed using gamma spectroscopy or another method of similar accuracy. The mixed samples shall be homogenized before analysis. If it is appropriate to send only part of a mixed sample for analysis, homogenisation of the mixed sample must take place in accordance with the requirements or guidance of the analytical laboratory. The result for the mixed sample analysis is assigned to the radioactive waste in all the barrels represented by the mixed sample.
Under certain conditions, mixed samples can be used for waste from:
- Cleaning of pipes from the same pipe string
- Emptying of one separator
- Emptying of a tank on board, such as a degassing tank and flotation tank
- Emptying of a desanding cyclone, mud cell and other equipment on board where sand and sludge can be separated
- Jetting operations
Prerequisites for the use of mixed samples:
- Mixed samples may only be used when it is reasonable to consider the waste to be homogeneous
- Waste from different types of equipment shall not be mixed
- When well streams from several fields are processed on a facility, and the well streams from the different fields enter different separators, the waste from these fields shall not be mixed either
- A mixed sample may only include waste coming from the same transport container (ship) and the number of barrels included in a mixed sample shall not exceed 25.