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Title: Status of R&D on Mitigating the Effects of Pressure Waves for the Spallation Neutron Source Mercury Target

Abstract

The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory has been conducting R&D on mitigating the effects of pressure waves in mercury spallation targets since 2001. More precisely, cavitation damage of the target vessel caused by the short beam pulse threatens to limit its lifetime more severely than radiation damage as well as limit its ultimate power capacity and hence its neutron intensity performance. The R&D program has moved from verification of the beam-induced damage phenomena to study of material and surface treatments for damage resistance to the current emphasis on gas injection techniques for damage mitigation. Two techniques are being worked on: injection of small dispersed gas bubbles that mitigate the pressure waves volumetrically; and protective gas walls that isolate the vessel from the damaging effects of collapsing cavitation bubbles. The latter has demonstrated good damage mitigation during in-beam testing with limited pulses, and adequate gas wall coverage at the beam entrance window has been demonstrated with the SNS mercury target flow configuration using a full scale mercury test loop. A question on the required area coverage remains which depends on results from SNS target post irradiation examination. The small gas bubble technique has been less effectivemore » during past in-beam tests but those results were with un-optimized and un-verified bubble populations. Another round of in-beam tests with small gas bubbles is planned for 2011. The first SNS target was removed from service in mid 2009 and samples were cut from two locations at the target s beam entrance window. Through-wall damage was observed at the innermost mercury vessel wall (not a containment wall). The damage pattern suggested correlation with the local mercury flow condition which is nearly stagnant at the peak damage location. Detailed post irradiation examination of the samples is under way that will assess the erosion and measure irradiation-induced changes in mechanical properties. Similar samples were cut from the second SNS target after it was removed from service in mid 2010. More extensive damage was observed on the target inner wall but damage to the containment wall was minimal.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1060243
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 10th International Workshop on Spallation Materials Technology (IWSMT-10), Beijing, China, 20101018, 20101022
Country of Publication:
United States
Language:
English
Subject:
mercury; spallation; target; cavitation; pitting; erosion; mitigation

Citation Formats

Riemer, Bernie, Wendel, Mark W, Felde, David K, Abdou, Ashraf A, and McClintock, David A. Status of R&D on Mitigating the Effects of Pressure Waves for the Spallation Neutron Source Mercury Target. United States: N. p., 2012. Web.
Riemer, Bernie, Wendel, Mark W, Felde, David K, Abdou, Ashraf A, & McClintock, David A. Status of R&D on Mitigating the Effects of Pressure Waves for the Spallation Neutron Source Mercury Target. United States.
Riemer, Bernie, Wendel, Mark W, Felde, David K, Abdou, Ashraf A, and McClintock, David A. 2012. "Status of R&D on Mitigating the Effects of Pressure Waves for the Spallation Neutron Source Mercury Target". United States.
@article{osti_1060243,
title = {Status of R&D on Mitigating the Effects of Pressure Waves for the Spallation Neutron Source Mercury Target},
author = {Riemer, Bernie and Wendel, Mark W and Felde, David K and Abdou, Ashraf A and McClintock, David A},
abstractNote = {The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory has been conducting R&D on mitigating the effects of pressure waves in mercury spallation targets since 2001. More precisely, cavitation damage of the target vessel caused by the short beam pulse threatens to limit its lifetime more severely than radiation damage as well as limit its ultimate power capacity and hence its neutron intensity performance. The R&D program has moved from verification of the beam-induced damage phenomena to study of material and surface treatments for damage resistance to the current emphasis on gas injection techniques for damage mitigation. Two techniques are being worked on: injection of small dispersed gas bubbles that mitigate the pressure waves volumetrically; and protective gas walls that isolate the vessel from the damaging effects of collapsing cavitation bubbles. The latter has demonstrated good damage mitigation during in-beam testing with limited pulses, and adequate gas wall coverage at the beam entrance window has been demonstrated with the SNS mercury target flow configuration using a full scale mercury test loop. A question on the required area coverage remains which depends on results from SNS target post irradiation examination. The small gas bubble technique has been less effective during past in-beam tests but those results were with un-optimized and un-verified bubble populations. Another round of in-beam tests with small gas bubbles is planned for 2011. The first SNS target was removed from service in mid 2009 and samples were cut from two locations at the target s beam entrance window. Through-wall damage was observed at the innermost mercury vessel wall (not a containment wall). The damage pattern suggested correlation with the local mercury flow condition which is nearly stagnant at the peak damage location. Detailed post irradiation examination of the samples is under way that will assess the erosion and measure irradiation-induced changes in mechanical properties. Similar samples were cut from the second SNS target after it was removed from service in mid 2010. More extensive damage was observed on the target inner wall but damage to the containment wall was minimal.},
doi = {},
url = {https://www.osti.gov/biblio/1060243}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2012},
month = {Sun Jan 01 00:00:00 EST 2012}
}

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