Clint, Something related that we saw was a "contamination" of the I-131 due to Mo-99 having a similar energy gamma. In our case, only the I-131 went up, somewhat erratically, and the other iodine isotopes behaved more normally. Although Westinghouse questioned the validity of our measurements, they did not suggest the root of the problem being Mo-99. The way to check for this issue is to perform a recount in ~2 weeks after the sample was pulled. Most of the MO-99 should be gone but a large percent of the I-131 is still left.

I'll check back on our cesium to see if it behaved normally but I thought I'd get this other "oddity" out there. Ron Niederer Byron 815-406-3443

-----Original Message----- From: respvr-bounces@retaqs.com [mailto:respvr-bounces@retaqs.com] Sent: Monday, February 06, 2006 8:19 PM To: 'RE Supervisors' Subject: [Respvr] Iodine/Cesium Mismatch Question

Has anyone seen an increase in RCS iodine activity in the RCS without a concurrent cesium indication? Xe-133/135 also increased. This occurred at steady state, full power conditions - no opportunity for washout from an existing failed rod. We are puzzled by the lack of cesium as all our models indicate that it should be present when the iodine increase occurred.

Clint Alday Reactor Engineering Waterford 3 calday@entergy.com _______________________________________________ Respvr mailing list Respvr@retaqs.com http://www.keffective.com/mailman/listinfo/respvr

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