*** tritium ***
tritium - plutonium, 16, high similarity
tritium - nuclear, 4, low similarity
tritium - radioactive, 16, high similarity
tritium - radon, 16, high similarity
tritium - uranium, 16, high similarity
tritium - smuggle, 4, low similarity
tritium - shipment, 4, low similarity
tritium - fissile, 4, low similarity
tritium - sure, 4, low similarity

*** plutonium ***
plutonium - tritium, 16, high similarity
plutonium - nuclear, 4, low similarity
plutonium - radioactive, 16, high similarity
plutonium - radon, 16, high similarity
plutonium - uranium, 16, high similarity
plutonium - smuggle, 4, low similarity
plutonium - shipment, 4, low similarity
plutonium - fissile, 4, low similarity
plutonium - sure, 4, low similarity

*** nuclear ***
nuclear - tritium, 4, low similarity
nuclear - plutonium, 4, low similarity
nuclear - radioactive, 4, low similarity
nuclear - radon, 4, low similarity
nuclear - uranium, 4, low similarity
nuclear - smuggle, 4, low similarity
nuclear - shipment, 4, low similarity
nuclear - fissile, 4, low similarity
nuclear - sure, 4, low similarity

*** radioactive ***
radioactive - tritium, 16, high similarity
radioactive - plutonium, 16, high similarity
radioactive - nuclear, 4, low similarity
radioactive - radon, 16, high similarity
radioactive - uranium, 16, high similarity
radioactive - smuggle, 4, low similarity
radioactive - shipment, 4, low similarity
radioactive - fissile, 4, low similarity
radioactive - sure, 4, low similarity

*** radon ***
radon - tritium, 16, high similarity
radon - plutonium, 16, high similarity
radon - nuclear, 4, low similarity
radon - radioactive, 16, high similarity
radon - uranium, 16, high similarity
radon - smuggle, 4, low similarity
radon - shipment, 4, low similarity
radon - fissile, 4, low similarity
radon - sure, 4, low similarity

*** uranium ***
uranium - tritium, 16, high similarity
uranium - plutonium, 16, high similarity
uranium - nuclear, 4, low similarity
uranium - radioactive, 16, high similarity
uranium - radon, 16, high similarity
uranium - smuggle, 4, low similarity
uranium - shipment, 4, low similarity
uranium - fissile, 4, low similarity
uranium - sure, 4, low similarity

*** smuggle ***
smuggle - tritium, 4, low similarity
smuggle - plutonium, 4, low similarity
smuggle - nuclear, 4, low similarity
smuggle - radioactive, 4, low similarity
smuggle - radon, 4, low similarity
smuggle - uranium, 4, low similarity
smuggle - shipment, 4, low similarity
smuggle - fissile, 4, low similarity
smuggle - sure, 4, low similarity

*** shipment ***
shipment - tritium, 4, low similarity
shipment - plutonium, 4, low similarity
shipment - nuclear, 4, low similarity
shipment - radioactive, 4, low similarity
shipment - radon, 4, low similarity
shipment - uranium, 4, low similarity
shipment - smuggle, 4, low similarity
shipment - fissile, 4, low similarity
shipment - sure, 4, low similarity

*** fissile ***
fissile - tritium, 4, low similarity
fissile - plutonium, 4, low similarity
fissile - nuclear, 4, low similarity
fissile - radioactive, 4, low similarity
fissile - radon, 4, low similarity
fissile - uranium, 4, low similarity
fissile - smuggle, 4, low similarity
fissile - shipment, 4, low similarity
fissile - sure, 4, low similarity

*** sure ***
sure - tritium, 4, low similarity
sure - plutonium, 4, low similarity
sure - nuclear, 4, low similarity
sure - radioactive, 4, low similarity
sure - radon, 4, low similarity
sure - uranium, 4, low similarity
sure - smuggle, 4, low similarity
sure - shipment, 4, low similarity
sure - fissile, 4, low similarity

Possible Roget's Thesaurus clusters:
------------------------------------
Head: 397 Calefaction
[tritium, plutonium, radioactive, radon, uranium]

The 10 largest clusters:
------------------------
Head: 397 Calefaction
[tritium, plutonium, radioactive, radon, uranium]

Words and phrases not in Roget's Thesaurus (20/30): 
--------------------------------------------------
[deuterium, lithium, thorium, nuclear material, radioactive material, radioactive substance, undine uta bloch von blottnitz, nuala ahern, mox, illegal traffic, iaea, trisaia, reprocess, mam?re, dessel, alex smith, sellafield, illicit traffic, nuclear weapon, familiarisation]