RE: Hot Particles/Un-Productive Surveys

[Glen.Vickers@ucm.com]

I believe the following excerpt below may be based on faulty logic.  The
most likely contributor to hot particles is Co-60, which is an activation
product, not a fuel product.  Minor clad defects will increase the coolant
inventory of iodines and noble gases, but are not likely to significantly
affect the levels of actual fuel particulate in the coolant.  I have seen a
fuel cycle such as this and no signficant increase was seen in the 10CFR61
difficult-to-measure radionuclides.  Remember the fuel pellet is a piece of
ceramic and I believe it takes thermal excursions more so than minor clad
defects to liberate significant amounts of fuel particulates.

When it comes to a PWR reactor, I believe the chemical clean up that is
performed as the unit is just shut down and before systems are open are the
greatest single contributor to actual suspended solids in the plant systems.
The clean up process solubilizes the corrosion layer which is primarily
composed of activation products and then later precipitates them out.  The
short term affects during the clean up are greatly increased uCi/cc (dose
rates too), then clean up is performed by resin beds and particulate
filters.  The increase and clean up efficiencies are of such a great
magnitude, that this process probably dwarfs other contributing processes.
I have also seen it written that solubilizing and not removing
non-radioactive forms of possible Fe or Mn essentially create a mass of
material available for activation the next fuel cycle.  I think the PWR
chemist is probably a little under appreciated...  I am at least smart
enough to know who has a large impact on the radiological conditions in the
plant, just wish I had more time to learn more.

Does anyone have any really good info on the Zr/Nb and their likely percent
contributions to reactor coolant from zircalloy activation and corrosion vs.
fission production?

Sincerely,
Glen Vickers
glen.vickers@ucm.com

	-----Original Message-----
	From:	Greg & Claudia Yuhas [SMTP:uhaskep@castles.com]
	Sent:	Thursday, February 18, 1999 4:15 PM
	To:	Multiple recipients of list
	Subject:	Hot Particles/Un-Productive Surveys

	Dr. Charles,

	The hot particle issue has been driven by power reactors
experiencing poor
	fuel clad integrity.  The decision to operate plants with poor fuel
	activity, but still within the Technical Specification limits for
reactor
	coolant activity, is a business decision.  One cost in making that
decision
	is the expense of managing the contamination during outages, spent
fuel
	handling, and fluid systems maintenance.

	
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