Characterization of argon-41 production at N Reactor Hanford Reservation, Washington

As a result of normal N Reactor operation, approximately 50,000 curies of 41Ar are released to the atmosphere at Hanford each year. Although the total population whole-body dose of 1.1 man-rem/year due to these 41Ar emissions is very small compared to the total population whole-body dose of 27,000 man-rem/year due to natural background, efforts are being directed towards reducing the 41Ar emissions. Analyses of the potential sources of 41Ar in N Reactor systems have been conducted. At least 70 percent of the total quantity of Ar that is released to the atmosphere is attributable to Ar that is present within the reactor gas system. Sources of Ar that have been investigated include entrance of air within the gas dryers, back diffusion of air through a reactor wall seal, dissolved Ar in the reactor cooling water, Ar blanket on the control rod hydraulic fluid, entrance of air during reactor shutdown periods, and air within the flux monitor detectors