Concern has been expressed regarding the long term build-up of long — lived isotopes within the atmosphere even though individual discharges are well within the recommended limits. This concern arises from discharges from fuel processing plants rather than from the nuclear power systems, but nevertheless a word of clarification is in order.

During fuel reprocessing the isotopes are removed with the exception of xenon, tritium, and krypton. However, after a 45-day hold-up to allow short-half-life isotopic decay, the xenons are removed and only tritium and 85Kr are released. They have half-lives of 10 and 12 yr and they therefore collect uniformly throughout the biosphere. What levels might these isotopes reach if nuclear expansion continues at its expected rate?

Figure 6.8 shows that the planetary build-up of tritium, assuming pro­jected nuclear power expansion, attains about 100 million Ci by the year 2000. Although this level sounds high, it is in fact about 6% of the maximum tritium activity due to weapons fallout at its peak in 1963 and it is only just equal to the natural production of tritium from the sun’s cosmic rays. The planetary exposure of the world’s population at the year 2000 would be about 0.002 mrem/yr. This assumes that half the world’s power by this year would be produced from nuclear plants.

The case of 85Kr is a slightly different matter because the atmospheric content is produced entirely from nuclear reactions. The present dose is less than 0.1% of the combined background due to cosmic rays and other natural background. However, Fig. 6.9 shows that by the year 2060 the accumulated krypton will increase to about a level which would give an exposure of approximately 1000 times that of tritium, with an annual individual dose of 50-100 mrem/yr. While this dose is still not dangerous, the accumulation does imply that some retention schemes should be em­ployed in fuel processing plants to avoid this accumulation. Present techno­logical capabilities promise effective future means of controlling krypton discharges by cryogenic concentration (10).

This short review of discharges into the air from fossil-fueled and nuclear — fueled plants shows that the nuclear plants are subjected to far greater control in discharge rates, and indeed they have less of an immediate prob­lem. Moreover, in the long run, biospheric accumulation from fuel pro­cessing plants, although the subject of sensation-seeking journalism, is not a problem. Even so, improvements in the management of 85Kr are to be expected.

[1] Note that the leakage is quoted in volume percent or weight percent per day at the design basis pressure unless otherwise noted.

8. Before operation a further license is required. Same steps are followed but with a FSAR

AEC Commissioners review

5. Licensing Board review all testimony and evidence, makes license decision

[3] DRL distributes copies to public and ACRS, DRL makes technical review and prepares analysis

[4] ACRS receives report, makes independent study, reports to Press and AEC Commissioners

Fig. 6.5. Licensing of power reactors: how central-station atomic power plants are licensed and regulated (7a).