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Parker's nanoflare model (1987) is widely used to describe the heating of the corona. However, the model is viable only if the number of events is large and covers the whole solar sphere. Klimchuk (2015) argued that more than 100,000 current sheets should exist in an active region to produce a sufficient heating of the corona up to 1 MK. In order to validate Klimchuk's model, we study the dynamics of a quiet-Sun region observed by Hinode/SOT. From a potential field model, we derive the existence of tangential discontinuities, signatures of current sheets. We obtain that, at a given time, there exists a large number of tangential discontinuities that have potentially a free energy of pico- to nano-flare energy. The current sheets are located in the photosphere and chromosphere, but just a small number of current sheet is located in the corona where the topology of the magnetic field is less tangled/twisted. The density of current sheets is constant in time. This analysis supports Klimchuk's argument regarding Parker's model, and also predicts energy releases at the picoflare scale.