[ RadSafe ] BWR N-16 question

John_Rich at fpl.com John_Rich at fpl.com
Wed May 28 16:02:26 CDT 2008

BWR people,

   Does anybody have any experience with real N-16 increases in BWR main
   steam that due to power uprates?

   Conventional wisdom is that the increased production of N-16 is balanced
   by the increased steam flow so that the concentration in steam is
   unchanged.  This has an implicit assumption that the overwhelming
   removal mechanism is N-16 carry-over to the steam that leaves the
   reactor vessel.

   However, in reality, N-16 carry-over may not be greater than radiodecay,
   and in this case, the concentration in main steam could go up in direct
   proportion to the concentration in reactor water, i.e. in direct
   proportion to the power uprate.

   I think this is more of an academic interest than a real issue because a
   few % increase in the main steam N-6 concentration would not show up as
   a significant increase in dose rates, and might not be measurable on the
   main steam line monitors because of their wide range.

   But I'd still like to get the story straigh.

   Thanx in advance  - -jmr

John Rich
(561) 691-2902

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