The simulation of the thermal response of the JET bulk tungsten divertor modules to real operational conditions demonstrates that the analyzed design provides more favourable conditions than before (600oC) for the temperature-vulnerable materials of the stack attachment (esp. Inconel spring discs), thereby increasing the attachment lifetime. The computation shows that the JET divertor unit can withstand up to five consecutive cycles, 10s long, of an evenly distributed heat loading (averaged heat flux of ~6.5MW/m2) with half-an-hour intervals before the springs reach their uppermost temperature limit. However, if we take into account (i) the real heat load distribution over the upper lamellae surface (shadowing effect), (ii) an initial temperature of the structure of 200oC, it may be that the temperature approaches 600oC after a single full-energy pulse.