Give the number of papers that were published on "IEEE Transactions on Nuclear Science" in 1999.
'IEEE Transactions on Nuclear Science' is the FullName of journal; 1999 refers to Year = '1999'; papers refers to Paper.Id
SELECT COUNT(T2.Id) FROM Journal AS T1 INNER JOIN Paper AS T2 ON T1.Id = T2.JournalId WHERE T1.FullName = 'IEEE Transactions on Nuclear Science' AND T2.Year = 1999