ML20211B877
| ML20211B877 | |
| Person / Time | |
|---|---|
| Issue date: | 02/13/1987 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20211B803 | List: |
| References | |
| FOIA-86-826 NUDOCS 8702190586 | |
| Download: ML20211B877 (2) | |
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COMMENTS ON TRANSUFANIC CONTAMINATION Experience with nuclear pcwer plants twenty years and more ago showed that a plant operating under normal conditions has very little transuranic contamination in its liquid effluents.
The U.S. Environmental Protection Agency (EPA) did scrre careful stuotes around four plants in the period 1966-1976, which are identified at nunbers one through four on the enclosed Appendix B.
Although these studies confirm that there are only traces of transuranics, the studies dic not go into that aspect in depth because it was already known that there was essentially r.cthing to look for.
Nevertheless, these studies are. gocc references in thct they provide in-depth documentation, from coherent studies, of the rocionuclides in the plant systems, in the plant effluents, and in the environment around the plants. The report that you referenced, NUREG/CR-1658, also supports this. Because the transuranic nuclides are so scerce in the effluents, anc because they are almost all alpha emitters (more significant with respect to biological effects than beta and garrca emitters), the effluer.t reporting requireaents call for reporting only gross alpha measuren.ents; the gross alpha measurements may also include some uranium and thorium and their daughters but ger,erally the results are n.uch smaller than the lir.its for release of the trar.suranic redionuclides, so that they serve to establish that such limits haven't been exceeced. Thus, with few exceptions, the semi-annual effluent repu ts icentified cn Appenc1x A shuw only small amcunts of "grcss alpha" activity, and do not otherwise mention transuranic nuclides. NRC's sunnary reports (e.g.12) do not even mention the gross alpha activity, because it is so insignificant.
The heightened environmental awareness of the late 1960's eventually led to the pronulgation of requirements to keep radioactivity in effluents As Low As Reasonobly Achievable (ALAPA); the requirements are specifiec as design objectives in 10 CFR Part 50 and Apperdix 1 thereto, and as standards in EPA's 40 CFR Part 190. Because of these ALARA requirerrents, most of the plants existing then had to upgract their waste treatment systems, reducing the radioactivity iri the effluents to even smalier levels.
Indeed, the last of EPA's four stuaies was cerrpleted ur. der pressure to complete the measuretrents at the Oyster Creek plant before the weste treatrrent systerns were upgraded and it becan.e even more difficult to neosure the radioactivity.
f.RC's Envirunn. ental Statements (e.g. 6, 7) show predicticr.s of Np-239 in the liquid effluents; our predictions are usually conservative, and Np-E39 is rarely detected in the effluents even though it is cetected in small concentrations in the primary coolant that passes through the reactor core. Np-239 is exceptional because it builds up to large quantities (more than a billion curies) in the reactor core (about 8 times any other radionuclide), because it decays by beta r
I emission with characteristic gammas which simplify its detection, and because it has a shcrt half-life (2.35 days) which makes it detectable even in very small mass concentrations.
hp-239 found in the environment can usually be considered reactor-produced because that produced in nuclear weapons tests decays away quickly after the explosion. Other transuranic nuclides (longer-lived) produced in weapcns tests have been depositec all over the earth, providing a "bactground" that tends to obscure the small amounts that night te released frcm nuclear power plants.
h6870213 BRACM86-826 ppg
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Comments on Transuranic Contamination Page 2 In summary, because the quantities released are so small, there are very few NRC reports that accress transuranic rele65es in routir.e effluents from corn.ercial nuclear power plants as a principle tcpic.
There are some excep-tional cirmcumstances, where plants and systtes have not performed as desired.
For example, 6t the Rancho Seco plant releases where little ailution water was available led tc a build up of radioactivity in the environment (8).
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