Several types of demo blankets are planned to be tested in the International Thermonuclear Experimental Reactor (ITER). Several horizontal ports at the equatorial plan in ITER are dedicated to such tests. A typical opening area at the mouth of each port of ~2.6m x 2.0 m is reserved to place multiple test modules with adequate shield. To extend the usefulness of these tests, it is required to simulate as much as possible the demo conditions (in terms of heating rate densities and profiles) under ITER operation scenario without imposing any stringent requirement on ITER operation itself. Because of the nature of the geometrical arrangement of these tests, the test modules are partially covering the plasma surface as opposed to the full coverage anticipated in demo reactors. Such partial coverage, in addition to the possibility of placing several modules of different composition in the same test port, the nuclear performance in each test module could be affected by the interfering effect arising from the presence of the neighboring modules. This nuclear interference has subsequent effects on the thermomechanical behavior of each test module. The present work examines such interference and explores means to decoupled this effect from the neutronics view point. The effect of such decoupling on the thermo-mechanical behavior of the test modules has also been investigated. The focus is placed on helium-cooled solid breeder (SB) test modules but the effects examined here could as well be present in other types of blanket modules. Some of the issues examined are briefly listed below:

(1) Effect of non-breeding blanket zones (basic shield blanket) on the nuclear performance of the breeding test modules: the basic blanket is mostly made of highly reflecting stainless steel material. Accordingly, substantial component of reflected neutrons could reach the test port and contribute to tritium breeding and heating rates, (2) Coupling between several test modules placed inside the test port: when more that one test module are placed in the test port, it is of importance to insure decoupling between these assemblies which is basically governed by the material and its thickness that separates these assemblies from one another, (3) Existing of differentials in the nuclear performance throughout the test modules in the poloidal direction: the front surfaces of the test modules will be placed at locations that could have different wall loading and hence differences in nuclear heating and breeding rates could be experienced, (4) Neutron and gamma-ray streaming to the back zones of the test port: Gaps and vacancies in the test port should be eliminated or at least minimized to decrease as possible the increase in the nuclear field behind the test modules through streaming paths. For example, in the helium-cooled test modules design proposed by the EU, edge-on arrangement of the structure, Be and the SB layers could results in different nuclear field attenuation in the radial direction due to the different attenuation capabilities of these materials and in particular the existing of the helium used as a coolant in the structural layers, and (5) Shielding of the TF coils on the sides of the test port from radiation streaming through vacancies in the test port: It is essential to ensure adequate shielding of the SCM and its insulating materials against neutrons and gamma rays streaming from gaps between test modules and/or at the outer edge of the port. The results from the parametric study performed to examine these issues will be included and discussed in this paper. Subsequent effect on the thermo-mechanical behavior of the helium-cooled SB test module will also be assessed in the present work.