Safe Handling of Insensitive High Explosive Weapon Subassemblies at the Pantex211 Plant

摘要

Conventional high explosives (CHE) are characterized by a sensitivity to211u001emechanical or thermal energy. Insensitive high explosives (IHE), on the other 211u001ehand, require extraordinarily high stimuli before violent reaction occurs. 211u001eTherefore, fewer constraints on handling IHE are required as compared with CHE. 211u001eBased on the measured differences in weapon subassemblies between explosives 211u001econtaining CHE and IHE, the two types of subassemblies are controlled differently 211u001ein Pantex facilities. For example, IHE subassemblies, including those containing 211u001eCHE, are allowed uncased in assembly bays, whereas uncased CHE subassemblies may 211u001ebe handled only in assembly cells. Some weapon subassemblies containing IHE also 211u001econtain CHE materials. In particular, boosters of many IHE subassemblies are made 211u001eof CHE. For such configurations, the likelihood of violent reaction in abnormal 211u001eenvironments at Pantex cannot be statistically defended on the basis of the small 211u001enumber of tests performed. In particular, the margin for a less-than-optimal 211u001estimulus of the CHE booster to detonate IHE is not well defined. The staff of the 211u001eDefense Nuclear Facilities Safety Board believes that additional evaluation of 211u001ethe technical basis for the use of separate controls for operations involving 211u001ecomposite IHE/CHE subassemblies is warranted. Additional engineering or 211u001eadministrative controls on operations involving IHE/CHE subassemblies may be 211u001enecessary to improve safety. Where significant uncertainties exist in the 211u001elikelihood estimates for a violent reaction of IHE under credible abnormal 211u001eenvironments, a vigorous program of additional tests and computer modeling may be 211u001erequired to improve confidence in the estimates.