The construction license establishes the prerequisites under which the com­missioning of a plant is conducted. These conditions include arrangements under which the RB will specify what is to be done, conditions under which approval must be given and where consent has to be sought before moving to the next stage of commissioning. Chapter 22 covers the activities to be conducted during commissioning.

Well before the end of construction, the licensee makes and implements adequate arrangements for commissioning the NPP, mainly with regard to those processes that may affect safety. Such arrangements need the approval of the RB. These arrangements provide documentation to justify the safety of the proposed commissioning. It is recommended that the licensee appoints a suitably qualified person or persons to control, witness, record and assess the results of any tests carried out in accordance with the require­ments of the commissioning arrangements. The licensee should ensure that full and accurate records are kept of the result of every test and operation carried out in pursuance of these requirements.

The RB considers the proposed arrangements for commissioning very closely and makes preparations for licensing this phase, and for witnessing the nuclear tests that are to be performed and analyzed. The RB creates a commissioning group with experience on the subject but, if that experience is missing, outsiders can be hired (usually commissioning experts from the RB in the country of origin of the project). Nevertheless, responsibility for making an analysis of the commissioning programme, establishing the limits and conditions for their conduct, witnessing the tests and accepting the results remains with the RB.

It is customary to divide the commissioning into stages. If the RB so specifies, the licensee should not commence commissioning, or proceed from one stage to the next, without the consent of the RB. The licensee should ensure that, once approved, no alteration or amendment is made to the arrangements unless the RB agrees to such alteration or amendment. The commissioning phase is terminated when all foreseen tests have been successfully conducted and approved by the RB.