  The hostile condition in a fusion tokomak reactor poses the main challenge in
the development and design of in-vessel components such as divertor and
breeding blanket due to fusion relevant irradiation conditions (14 MeV) and
large thermal loads. The current work describes the employment of an integrated
experimental-numerical approach to assess the microstructure evolution of
dislocation loops and voids in tungsten proposed for fusion application.
Cluster dynamics (CD) model is implemented and simulations are performed on the
irradiated tungsten Disk shape Compact Tension (DCT) specimen used in the
experimental test. TEM characterisation is performed on the DCT specimen
irradiated at 400 {\deg}C and 600 {\deg}C with around 1 dpa, respectively. The
dpa rate and cascade overlap rate from the experiments and SPECTRA-PKA code,
respectively, are implemented in the CD model. Based on the comparison between
experimental and computational results, the dose and temperature dependence of
irradiation-induced defects (dislocation loops, voids, c15 clusters) are
clearly observed. Trap mediated diffusion is studied and the impact of cascades
with the pre-existing defects is analysed through full cascade overlap mode and
the consequent influence on the defect concentration is evaluated. The exchange
of self-interstitial atoms (SIAs) and the change in the size of loops through
reaction between <111> and <100> loops are studied in detail by means of the
transfer rate of the SIAs.
