ISO 9001:2015 does not specify any time frame for closing nonconformities raised after an internal audit. A previous version of the standard (ISO 9001:2000) had in its content the following text “ensure that actions are taken without undue delay to eliminate detected nonconformities and their causes”. Although that text disappeared that is the spirit I follow. It is not possible to specify a rigid timeframe because different nonconformities, with different causes, will take different amount of time to be closed.
The following material will provide you information about internal audits: