From: "Frank Haber" 

Thanks.  60% less radioactive is correct.  The paper says that 60%, though,
stays as a metallic slug.  It seems unsure whether a big blob of metallic
U238 is pyrophoric.  Fragmented stuff, though, must be real nice - slivers
of rod that consume themselves to a hundred rads of oxide smoke within
minutes.  What a cute sparkler.

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