131I decay constant=3.59×10−3 h−1



purification removal constant




purification system flow rate (kg/h)



RCS mass inventory (kg)



purification system decontamination factor.

An example of calculation can be found in the literature(16).

3.5.4 Soluble Fission Products Releases

As mentioned earlier, Cs, Sr and other soluble fission products also spike during reactor shutdown. An example of Cs isotopes spiking in a PWR is shown in Figure 3–9.


(1) A.H.Booth, A Method of Calculating Fission Gas Diffusion from UO2 and Its Application to the X-2-F Loop Test, September 1957 (AECL CRDC-721).

(2) S.D.Beck, The Diffusion of Radioactive Fission Products from Porous Fuel Elements , April 1960 (BMI-1433).

(3) American Nuclear Society, “Method for Calculating the Fractional Release of Volatile Fission Products from Oxide Fuel,” ANSI/ANS-5.4–1982.

(4) R.A.Lorenz, J.L.Collins, and A.P.Malinauskas, Nucl. Tech. Vol 46, 404 (1979).

(5) J.M.Skarpelos and R.S.Gilbert, “Technical Derivation of BWR 1971 Design Basis Radioactive Material Source Terms,” March 1971 (NEDO-10871).

(6) EPRI, “Failed Fuel Action Plan Guidelines,” NP5521-SR (Nov. 1987).

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