Re: 10 CFR 61 Scaling Factors

[Gv1@AOL.COM]

In a message dated 7/25/02 9:28:02 AM Central Daylight Time, cflaney@BELLSOUTH.NET writes:



> radsafe@list.vanderbilt.edu


With respect to trying to scale reactor wastes to Ce-144, it is difficult to get positive analysis results for Ce-144 to scale to.  Even when you're an operating reactor with fresh waste streams and although you pay extra for chemical separation to increase the yield for Ce-144, you'll probably get LLD values half of the time.  The industry standard waste classification program Radman requires Ce-144 to be present in the waste stream to scale in transuranics.  I believe you may need a better radionuclide to scale to for your old waste streams.  Even when the NRC approved the Radman code, they said their methodology for scaling was acceptable, not that it was the best method available.  With this being said, Radman is still the best code around and I support if fully.  


At Braidwood Nuclear Power Station we scale our reactor-produced transuranics to Pu-239 and Pu-239 back to Co-60.  You will get far more positive results looking for Pu-239 than Ce-144.  Additionally, Pu-239 and the other transuranics you're interested in are all produced by the same mechanism.  They are activated fuel products, not fission products.  Our Pu-239/transuranic scatter plots over a 5 year period have a very tight fit.  Note that Ce-144 is not generated by the same mechanisms as transuranics, not as chemically similar per the periodic table, and the difficulty in getting consistent analysis results.  Recalling from memory, I believe our scatter plots for Ce-144/transuranics have a greater variance than Pu-239/transuranics.  By recognizing the previous issues, I mean the Ce-144/transuranic scaling factor may be driven more by luck than a chemical/physical/production property shared with transuranics.


To make the Radman code happy, we throw in a Ce-144 value whether it be a real value or an LLD.  Our scaling factors for transuranics are actually tied to Pu-239.  Using Ce-144 to scale transuranics to is an industry standard practice, but Pu-239 is a better indicator.


In general your scaling factors for transuranics should be quite stable and reproducible.  You shouldn't have to use any real professional judgement until you get to radionuclides such as C-14, Sr-90, Tc-99, and I-129....


Glen Vickers

LaSalle Nuclear Power Station