FITNET

Irradiation raises yield strength and lowers fracture toughness, so the assessment point of a cracked plate drifts toward the failure assessment line year by year. This post assesses the FITNET training example 'Plate under neutronic irradiation' with the BS 7910 Clause 7 fracture assessment calculator: 12 assessment points are compared one by one with the source, and the most critical point (year 20, 350 MPa) has a reserve factor on load of 1.19 against about 1.2 read from the source chart. All inputs, calculation steps and comparison tables are included.

FITNET's SSTP10 worked example — a welded stainless-steel wide plate with a through-thickness crack failing by ductile tearing. This post works out the assessment point in mechCalc's BS 7910 Clause 7 fracture assessment calculator (the calculator does not do a ductile tearing analysis, so K_mat is converted point by point and entered directly), shows where it lands on the Failure Assessment Diagram, and compares it point by point with FITNET: the horizontal coordinate L_r is close to the literature (0.511 vs 0.51), while the vertical coordinate K_r cannot be compared directly because the source includes an unquantified welding residual stress.

In the fracture-mechanics and fitness-for-service (FFS) literature, FITNET is a name you cannot avoid. This article traces the origins of the FITNET EU project from public sources: how it descends from SINTAP, who led and funded it, its scale, what the four modules of the FITNET FFS Procedure each cover, and why its fracture module is highly comparable to BS 7910.