When at least 4 TNTs explode at the fourteenth pixel in a block, for example, y = 0.875, y = 4.875 and y = 5.875, even if the TNTs are overlapped, only blocks like waterlogged ender chest, waterlogged chest, ender chest, waterlogged fences and waterlogged walls can ensure that blocks around TNTs will not be destroyed. However, pure water, lava, waterlogged blocks except chests, ender chests, fences and walls still cannot ensure that TNTs will not destroy blocks around. The problem is, both the water and the lava is a little bit higher than chests when there are blocks surrounding them. 

Way to Produce: 

i. Give yourself a command block and then type in the following: 

    /summon tnt 0.49 63.875 0.5 {fuse:0}

ii. Replace the targeted block at (0, 63, 0) with a waterlogged chest

iii. Put a block of obsidian at (0, 63, 4) and a lever on top of it. Then, place four identical command blocks mentioned in step i around the stone at the same y level, and make sure that there are blocks surrounding the waterlogged chest

iv. Replace the waterlogged chest with water or lava, then repeat step iii

v. If you find out that after you activate the lever, it soon disappears, then you succeed