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Title: Plutonium-238 alpha-decay damage study of the ceramic waste form.

Abstract

An accelerated alpha-decay damage study of a glass-bonded sodalite ceramic waste form has recently been completed. The purpose of this study was to investigate the physical and chemical durability of the waste form after significant exposure to alpha decay. This accelerated alpha-decay study was performed by doping the ceramic waste form with {sup 238}Pu which has a much greater specific activity than {sup 239}Pu that is normally present in the waste form. The alpha-decay dose at the end of the four year study was approximately 1 x 10{sup 18} alpha-decays/gram of material. An equivalent time period for a similar dose of {sup 239}Pu would require approximately 1100 years. After four years of exposure to {sup 238}Pu alpha decay, the investigation observed little change to the physical or chemical durability of the ceramic waste form (CWF). Specifically, the {sup 238}Pu-loaded CWF maintained it's physical integrity, namely that the density remained constant and no cracking or phase de-bonding was observed. The materials chemical durability and phase stability also did not change significantly over the duration of the study. The only significant measured change was an increase of the unit-cell lattice parameters of the plutonium oxide and sodalite phases of the material andmore » an increase in the release of salt components and plutonium of the waste form during leaching tests, but, as mentioned, these did not lead to any overall loss of waste form durability. The principal findings from this study are: (1) {sup 238}Pu-loaded CWF is similar in microstructure and phase composition to referenced waste form. (2) Pu was observed primarily as oxide comprised of aggregates of nano crystals with aggregates ranging in size from submicron to twenty microns in diameter. (3) Pu phases were primarily found in the intergranular glassy regions. (4) PuO phase shows expected unit cell volume expansion due to alpha decay damage of approximately 0.7%, and the sodalite phase unit cell volume has expanded slightly by 0.3% again, presumably due to alpha-decay damage. (5) No bulk sample swelling was observed. (6) No amorphization of sodalite or actinide bearing phases was observed after four years of alpha-decay damage. (7) No microcracks or phase de-bonding were observed in waste form samples aged for four years. (8) In some areas of the {sup 238}Pu doped ceramic waste form material bubbles and voids were found. Bubbles and voids with similar size and density were also found in ceramic waste form samples without actinide. These bubbles and voids are interpreted as pre-existing defects. However, some contribution to these bubbles and voids from helium gas can not be ruled out. (9) Chemical durability of {sup 238}Pu CWF has not changed significantly after four years of alpha-decay exposure except for an increase in the release of salt components and Pu. Still, the plutonium release from CWF is very low at less than 0.005 g/m{sup 2}.« less

Authors:
 [1];  [1];  [1];  [1];  [2];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [3]
  1. U.S. Department of Energy, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415
  2. U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001
  3. UOP LLC, 25 E Algonquin Road, Des Plaines, IL 60017
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
885495
Report Number(s):
ANL-NT-239
TRN: US0603977
DOE Contract Number:
W-31-109-ENG-38
Resource Type:
Technical Report
Country of Publication:
United States
Language:
ENGLISH
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; ACTINIDES; ALPHA DECAY; BEARINGS; BUBBLES; CERAMICS; DEFECTS; HELIUM; LATTICE PARAMETERS; LEACHING; MICROSTRUCTURE; OXIDES; PHASE STABILITY; PLUTONIUM; PLUTONIUM 238; PLUTONIUM OXIDES; SWELLING; WASTE FORMS; NESDPS Office of Nuclear Energy Space and Defense Power Systems

Citation Formats

Frank, S M, Barber, T L, Cummings, D G, DiSanto, T, Esh, D W, Giglio, J J, Goff, K M, Johnson, S G, Kennedy, J R, Jue, J-F, Noy, M, O'Holleran, T P, and Sinkler, W. Plutonium-238 alpha-decay damage study of the ceramic waste form.. United States: N. p., 2006. Web. doi:10.2172/885495.
Frank, S M, Barber, T L, Cummings, D G, DiSanto, T, Esh, D W, Giglio, J J, Goff, K M, Johnson, S G, Kennedy, J R, Jue, J-F, Noy, M, O'Holleran, T P, & Sinkler, W. Plutonium-238 alpha-decay damage study of the ceramic waste form.. United States. doi:10.2172/885495.
Frank, S M, Barber, T L, Cummings, D G, DiSanto, T, Esh, D W, Giglio, J J, Goff, K M, Johnson, S G, Kennedy, J R, Jue, J-F, Noy, M, O'Holleran, T P, and Sinkler, W. Mon . "Plutonium-238 alpha-decay damage study of the ceramic waste form.". United States. doi:10.2172/885495. https://www.osti.gov/servlets/purl/885495.
@article{osti_885495,
title = {Plutonium-238 alpha-decay damage study of the ceramic waste form.},
author = {Frank, S M and Barber, T L and Cummings, D G and DiSanto, T and Esh, D W and Giglio, J J and Goff, K M and Johnson, S G and Kennedy, J R and Jue, J-F and Noy, M and O'Holleran, T P and Sinkler, W},
abstractNote = {An accelerated alpha-decay damage study of a glass-bonded sodalite ceramic waste form has recently been completed. The purpose of this study was to investigate the physical and chemical durability of the waste form after significant exposure to alpha decay. This accelerated alpha-decay study was performed by doping the ceramic waste form with {sup 238}Pu which has a much greater specific activity than {sup 239}Pu that is normally present in the waste form. The alpha-decay dose at the end of the four year study was approximately 1 x 10{sup 18} alpha-decays/gram of material. An equivalent time period for a similar dose of {sup 239}Pu would require approximately 1100 years. After four years of exposure to {sup 238}Pu alpha decay, the investigation observed little change to the physical or chemical durability of the ceramic waste form (CWF). Specifically, the {sup 238}Pu-loaded CWF maintained it's physical integrity, namely that the density remained constant and no cracking or phase de-bonding was observed. The materials chemical durability and phase stability also did not change significantly over the duration of the study. The only significant measured change was an increase of the unit-cell lattice parameters of the plutonium oxide and sodalite phases of the material and an increase in the release of salt components and plutonium of the waste form during leaching tests, but, as mentioned, these did not lead to any overall loss of waste form durability. The principal findings from this study are: (1) {sup 238}Pu-loaded CWF is similar in microstructure and phase composition to referenced waste form. (2) Pu was observed primarily as oxide comprised of aggregates of nano crystals with aggregates ranging in size from submicron to twenty microns in diameter. (3) Pu phases were primarily found in the intergranular glassy regions. (4) PuO phase shows expected unit cell volume expansion due to alpha decay damage of approximately 0.7%, and the sodalite phase unit cell volume has expanded slightly by 0.3% again, presumably due to alpha-decay damage. (5) No bulk sample swelling was observed. (6) No amorphization of sodalite or actinide bearing phases was observed after four years of alpha-decay damage. (7) No microcracks or phase de-bonding were observed in waste form samples aged for four years. (8) In some areas of the {sup 238}Pu doped ceramic waste form material bubbles and voids were found. Bubbles and voids with similar size and density were also found in ceramic waste form samples without actinide. These bubbles and voids are interpreted as pre-existing defects. However, some contribution to these bubbles and voids from helium gas can not be ruled out. (9) Chemical durability of {sup 238}Pu CWF has not changed significantly after four years of alpha-decay exposure except for an increase in the release of salt components and Pu. Still, the plutonium release from CWF is very low at less than 0.005 g/m{sup 2}.},
doi = {10.2172/885495},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Mar 27 00:00:00 EST 2006},
month = {Mon Mar 27 00:00:00 EST 2006}
}

Technical Report:

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  • Argonne National Laboratory has developed a glass-bonded sodalite ceramic waste form to immobilize fission products and plutonium that accumulate during the electrometallurgical conditioning of spent nuclear fuel. To investigate the effects of alpha decay damage on the structure and leaching characteristics of the ceramic material, {sup 238}Pu has been incorporated into the ceramic waste form. The {sup 238}Pu, with its high specific activity, significantly increases the rate of alpha damage to the waste form. Long term studies have begun with periodic examination of the {sup 238}Pu loaded ceramic material. A number of characterization techniques are used to study the alphamore » decay damage on the structure of the waste form. In addition, PCT type leachate studies will be performed to determine the effect of alpha decay damage on the durability of the ceramic waste form. Preliminary results from this study are presented.« less
  • No abstract prepared.
  • Argonne National Laboratory has developed a glass-bonded sodalite ceramic waste form to immobilize fission products and plutonium that accumulate during the electrometallurgical conditioning of spent nuclear fuel. To investigate the effects of alpha decay damage on the structure and leaching characteristics of the ceramic material, {sup 238}Pu has been incorporated into the ceramic waste form. The {sup 238}Pu,with its higher specific activity, significantly increases the rate of alpha damage to the waste form. Long term studies have begun with periodic examination of the {sup 238}Pu loaded ceramic material. A number of characterization techniques are used to study the alpha decaymore » damage on the structure of the waste form. In addition, PCT type leachate studies will be performed to determine the effect of alpha decay damage on the durability of the ceramic waste form. Preliminary results from this study are presented.« less
  • Two methods are described in this report for the determination of plutonium-236 traces in plutonium-238 by a spectrometry using semi-conductor detectors. The first method involves a direct comparison of the areas under the peaks of the {alpha} spectra of plutonium-236 and plutonium-238. The electrolytic preparation of the sources is carried out after preliminary purification of the plutonium. The second method makes it possible to determine the {sup 236}Pu/{sup 238}Pu ratio by comparing the areas of the {alpha} peaks of uranium-232 and uranium-234, which are the decay products of the two plutonium isotopes respectively. The uranium in the source, also depositedmore » by electrolysis, is separated from a 1 mg amount of plutonium either by a T.L.A. extraction, or by the use of ion-exchange resins. The report ends with a discussion of the results obtained with plutonium of two different origins. (authors) [French] Deux methodes de determination de traces de plutonium-236 dans du plutonium-238 par spectrometrie {alpha} a l'aide de detecteurs a semi-conducteurs sont decrites dans ce rapport. La premiere fait intervenir la comparaison directe des aires comprises sous les pics des spectres a du plutonium- 236 et du plutonium-238. La preparation electrolytique des sources est faite apres purification prealable du plutonium. La seconde permet de determiner le rapport {sup 236}Pu/{sup 238}Pu en comparant les aires des pics {alpha} de l'uranium 232 et de l'uranium 234, fils respectifs des deux isotopes du plutonium. L'uranium de la source egalement deposee par electrolyse est separe d'une quantite de 1 mg de plutonium, soit par extraction a la T.L.A., soit a l'aide de resines echangeuses d'ions. La discussion des resultats obtenus en utilisant du plutonium de deux provenances distinctes termine l'expose. (auteurs)« less
  • A glass-bonded, sodalite ceramic waste form that contains fission products, uranium, and plutonium is intended for disposition in a geologic repository. Over the many years the waste is expected to be in the repository, there is a potential for waste form degradation due to alpha decay damage. To investigate the effects of alpha-decay damage in glass-bonded, sodalite ceramic waste forms, several waste forms were produced with a {sup 238}Pu loading of 1.8 weight percent. This loading is roughly ten times greater than the plutonium loading for all isotopes in the waste form intended for the repository. Due to the highermore » specific activity of {sup 238}Pu as well as a higher fraction of total plutonium, the same number of alpha decays per gram of material has been achieved after four years as a waste form of nominal composition after ten thousand years. This paper describes the results of different tests near the completion of a four-year study. Trends of these {sup 238}Pu-doped waste forms include volume expansion of crystalline phases and possible increases in the release rates of several elements in the chemical durability tests. There have not yet been any indications of macroscopic swelling by density measurements, amorphization by x-ray diffraction, or microstructural changes by electron microscopy. Overall, the observed changes to the waste form due to alpha-decay are not of sufficient magnitude yet to cause concern over waste form degradation.« less