Performance assessment modeling of high level nuclear wasteforms from the pyroprocess fuel cycle Page: 5 of 6
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0.1% were utilized for LMR and LWR front end fuel
processing, respectively9. Actinide losses were assumed to
be equally distributed between the mineral and metallic
The results are presented as complementary cumulative
distribution functions. Figures I and 2 provide the total
cumulative actinide and fission product releases (Ci) from
each wasteform at 10,000 and 50,000 years following
emplacement for wastes derived from an LMR closed fuel
cycle. Figures 3 and 4 provide the cumulative actinide and
fission product release from each wasteform that arise from
an LWR actinide recycle front end pyroprocessing campaign
at 10,000 and 50,000 years. Over 10000 years, the waste is
well contained as the probability of any release is less than
0.05%. At 50000 years, the probability of release is
increased dramatically, especially for the fission products.
It can be seen that in terms of Curies released, that at a
given release level, the probability of exceeding that level is
greatest for the fission products. In addition, the maximum
release obtained is larger by one to two orders of magnitude
for the fission products. The relative toxicity of the fission
products, however, is several orders of magnitude less than
that of the actinides0. Therefore, the "toxicity" release rates
of the fission products and actinides are comparable.
Regarding isotopic contributions, the total actinide
release was found to be dominated by Pu239 and Pu2" for the
electrorefiner metallic and'nineral wasteforms derived from
both LMR and LWR actinide recycle pyroprocesses. For the
LMR wasteforms (Figures 1 and 2), the total fission product
release is dominated by Tc" for the metallic wasteform and
Se79 for the mineral wasteform. The contribution of Se79 to
the total fission product release is negligible when compared
to that from Tc". As shown in Figures 3 and 4, Tc99 from the
salt purification - metallic wasteform dominates the fission
product release for LWR actinide recycle wasteforms.
IV. CONCLUSION AND FUTURE WORK
PA analyses have been completed to estimate the
behavior of wasteforms generated from the pyroprocessing
of spent nuclear fuel (LWR and LMR). The results
demonstrate that the release (Ci) of radionuclides from
pyroprocess wasteforms is dominated by the release of Tc"
from the metallic wasteforms. The actinide release is
dominated by Pu239 and Pu240. Although the actinide release
is one to two orders of magnitude lower, the "toxicity" release
will be comparable to the fission products.
Future work includes a detailed comparison of the
performance of the various pyroprocess wasteforms with
directly disposed LWR spent fuel. Preliminary calculations
indicate that the actinide releases are significantly reduced.
In addition, these calculations will be repeated using
another performance assessment tool to obtain independent
results for comparison.
This work partially supported by U.S. Government
1. Phase 2: Demonstration of a Risk-Based Approach to
High-Level Radioactive Waste Repository Evaluation
Electric Power Research Institute, 1992, EPRI-TR-
2. Total System Performance Assessment - 1993: An
Evaluation of the Potential Yucca Mountain
Repository, Prepared for the U.S. Department of
Energy By Intera, Inc. March 1994, Document
3. Total - System Performance Assessment for Yucca
Mountain - SNL Second Iteration (TSPA-1993)
Sandia National Laboratory, _1194, SAND-93-2675.
4. W.H. Hannum, J.E. Battles, T.R. Johnson, C.C.
McPheeters, "Actinide Consumption: Nuclear
Resource Conservation Without Breeding,"
Proceedings of the American Power Conference,
Volume 53-1, 1991, p. 1208.
5. Projected Waste Packages Resulting From Alternative
Spent Fuel Separation Processes Electric Power
Research Institute, 1991, EPRI-NP-7262.
6. The Effects of Transuranic Separation on Waste
Disosal, Electric Power Research Institute, 1991,
7. IMARC: Integrated Multiple Assumptions and
Release Calculations User's Manual, Developed by
Risk Engineering Corporation for Electric Power
Research Institute, Palo Alto CA, 1993.
8. W.M. Nutt, "Performance Assessment Modeling of
High Level Nuclear Waste Containers," High Level
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Sixth International Conference. Las Vegas. Nevada,
9. Personal Communication with J.P. Ackerman,
Argonne National Laboratory, January 13,1995.
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Nutt, W.M.; Hill, R.N. & Bullen, D.B. Performance assessment modeling of high level nuclear wasteforms from the pyroprocess fuel cycle, article, June 1, 1995; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc742888/m1/5/: accessed May 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.