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Title: Factors influencing moisture analysis in the 3013 destructive examination surveillance program

Abstract

Thermogravimetric analysis of a solid sample with mass spectrometry (TGA-MS) of the evolved gas is used in the destructive examination (DE) portion of the Integrated Surveillance Program to quantify the moisture content of the material stored in a 3013 container. As with any measurement determined from a small sample, the collection, storage, transportation, and handling of the sample can affect its ability to represent the properties of the bulk material. During the course of the DE program, questions have periodically arisen concerning the ability of the moisture sample to reflect reliably the actual moisture content of the entire material stored in the 3013 container. Most concerns are related to the ability to collect a representative sample and to preserve the moisture content of the sample between collection and analysis. Recent delays in analysis caused by maintenance issues with the TGA-MS instrument presented a unique opportunity to document and quantify the effects various factors have on the TGA-MS moisture measurement. This report will use recent data to document the effects that current sample collection and handling practices have on the TGA-MS moisture measurement. Some suggestions will be made which could improve the current sample collection and handling practices for the TGA-MSmore » moisture measurement so that the analytical results more accurately reflect the moisture content of the material stored in the 3013 container.« less

Authors:
 [1]
  1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
Publication Date:
Research Org.:
Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1406121
Report Number(s):
SRNL-STI-2017-00419
TRN: US1800015
DOE Contract Number:
AC09-08SR22470
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; THERMAL GRAVIMETRIC ANALYSIS; MOISTURE; CONTAINERS; DESTRUCTIVE TESTING; TGA; MS; moisture; 3013; surveillance; humidity

Citation Formats

Scogin, J. H. Factors influencing moisture analysis in the 3013 destructive examination surveillance program. United States: N. p., 2017. Web. doi:10.2172/1406121.
Scogin, J. H. Factors influencing moisture analysis in the 3013 destructive examination surveillance program. United States. doi:10.2172/1406121.
Scogin, J. H. 2017. "Factors influencing moisture analysis in the 3013 destructive examination surveillance program". United States. doi:10.2172/1406121. https://www.osti.gov/servlets/purl/1406121.
@article{osti_1406121,
title = {Factors influencing moisture analysis in the 3013 destructive examination surveillance program},
author = {Scogin, J. H.},
abstractNote = {Thermogravimetric analysis of a solid sample with mass spectrometry (TGA-MS) of the evolved gas is used in the destructive examination (DE) portion of the Integrated Surveillance Program to quantify the moisture content of the material stored in a 3013 container. As with any measurement determined from a small sample, the collection, storage, transportation, and handling of the sample can affect its ability to represent the properties of the bulk material. During the course of the DE program, questions have periodically arisen concerning the ability of the moisture sample to reflect reliably the actual moisture content of the entire material stored in the 3013 container. Most concerns are related to the ability to collect a representative sample and to preserve the moisture content of the sample between collection and analysis. Recent delays in analysis caused by maintenance issues with the TGA-MS instrument presented a unique opportunity to document and quantify the effects various factors have on the TGA-MS moisture measurement. This report will use recent data to document the effects that current sample collection and handling practices have on the TGA-MS moisture measurement. Some suggestions will be made which could improve the current sample collection and handling practices for the TGA-MS moisture measurement so that the analytical results more accurately reflect the moisture content of the material stored in the 3013 container.},
doi = {10.2172/1406121},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month =
}

Technical Report:

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  • Thermogravimetric analysis with mass spectroscopy of the evolved gas (TGA-MS) is used to quantify the moisture content of materials in the 3013 destructive examination (3013 DE) surveillance program. Salts frequently present in the 3013 DE materials volatilize in the TGA and condense in the gas lines just outside the TGA furnace. The buildup of condensate can restrict the flow of purge gas and affect both the TGA operations and the mass spectrometer calibration. Removal of the condensed salts requires frequent maintenance and subsequent calibration runs to keep the moisture measurements by mass spectroscopy within acceptable limits, creating delays in processingmore » samples. In this report, the feasibility of determining the total moisture from TGA-MS measurements at a lower temperature is investigated. A temperature of the TGA-MS analysis which reduces the complications caused by the condensation of volatile materials is determined. Analysis shows that an excellent prediction of the presently measured total moisture value can be made using only the data generated up to 700 °C and there is a sound physical basis for this estimate. It is recommended that the maximum temperature of the TGA-MS determination of total moisture for the 3013 DE program be reduced from 1000 °C to 700 °C. It is also suggested that cumulative moisture measurements at 550 °C and 700°C be substituted for the measured value of total moisture in the 3013 DE database. Using these raw values, any of predictions of the total moisture discussed in this report can be made.« less
  • The DOE 3013 storage standard requires nested, welded 300 series stainless steel containers to store plutonium-bearing materials for up to 50 years. Packaged contents include stabilized plutonium-bearing residues that contain chloride salts and a low (< 0.5 weight %) water content. The DOE 3013 STD requires surveillance of the packages over the 50 year lifetime. These surveillance requirements have been further defined by the Integrated Surveillance Program to include both non-destructive examination (NDE) and destructive examination (DE) of the 3013 container. The DE portion of surveillance involves examining the 3013 nested containers, analyzing the head space gas, and evaluating themore » plutonium oxide chemistry. At SRS, the stored 3013 containers will undergo preparation for the DE surveillance activities in facilities located in K-Area. The actual DE surveillance will be performed in SRNL. This report provides preliminary functional requirements for the destructive examination (DE) of plutonium-bearing oxide materials and containers in support of K-Area Interim Surveillance (KIS). The KIS project will install interim facilities to prepare the samples for analysis in SRNL. This document covers the requirements for the interim period beginning in 2007, and lasting until the Container Storage and Surveillance Capability (CSSC) project provides the permanent facilities in K-Area to perform sampling and repackaging operations associated with the 3013 container storage and surveillance program. Initial requirements for the CSSC project have been previously defined in WSRC-TR-2004-00584 ''Plutonium Surveillance Destructive Examination Requirements at Savannah River National Laboratory''. As part of the Plutonium Surveillance Program of 3013 Containers at the Savannah River Site (SRS), the Savannah River National Laboratory (SRNL) will receive the emptied 3013 container components, plutonium oxide samples and headspace gas samples from K-Area. The DE program scope includes chemical and metallurgical analyses for a maximum of 25 DE sets a year to provide essential data in support of the SRS Plutonium Surveillance Program. The normal operation is expected to be approximately 15 DE sets a year.« less
  • The K-Area Materials Storage (KAMS) Documented Safety Analysis (DSA) requires a surveillance program to monitor the safety performance of 3013 containers and 9975 shipping packages stored in KAMS. The SRS surveillance program [Reference 1] outlines activities for field surveillance and laboratory tests that demonstrate the packages meet the functional performance requirements described in the DSA. The SRS program also supports the complexwide Integrated Surveillance Program (ISP) [Reference 2] for 3013 containers. The purpose of this report is to provide a summary of the SRS portion of the surveillance program activities through fiscal year 2010 (FY10) and formally communicate the interpretationmore » of these results by the Surveillance Program Authority (SPA). Surveillance for the initial 3013 container random sampling of the Innocuous bin and the Pressure bin has been completed and there has been no indication of corrosion or significant pressurization. The maximum pressure observed was less than 50 psig, which is well below the design pressure of 699 psig for the 3013 container [Reference 3]. The data collected during surveillance of these bins has been evaluated by the Materials Identification and Surveillance (MIS) Working Group and no additional surveillance is necessary for these bins at least through FY13. A decision will be made whether additional surveillance of these bins is needed during future years of storage and as additional containers are generated. Based on the data collected to date, the SPA concludes that 3013 containers in these bins can continue to be safely stored in KAMS. This year, 13 destructive examinations (DE) were performed on random samples from the Pressure & Corrosion bin. To date, DE has been completed for approximately 30% of the random samples from the Pressure & Corrosion bin. In addition, DE has been performed on 6 engineering judgment (EJ) containers, for a total of 17 to date. This includes one container that exceeded the 3013 Standard moisture limit which was opened at LANL. The container pieces and an oxide sample were sent to SRNL for examination in FY11. No significant pressurization has been observed for the Pressure & Corrosion bin containers. Relatively minor corrosion has been observed on some convenience containers and the inside of two inner containers. While the limited extent of corrosion does not jeopardize the integrity of the outer 3013 containers, it does highlight the importance of continuing to perform DE and the Shelf Life program to assure that the corrosion rate is not accelerating or changing to a different corrosion mechanism (e.g., stress corrosion cracking). Statistical sampling is currently scheduled to be completed in FY17, but there is a proposed reduction of the number of DE's per year for FY11 and beyond which may delay the completion date. Since 3013 containers are stored inside 9975 containers, surveillances of 9975 containers are performed in conjunction with 3013 container surveillances. Results of 9975 container nondestructive examinations (NDEs) and DEs indicate that the containers will provide adequate protection of the 3013 containers in K-Area storage for at least 15 years [Reference 4].« less
  • Techniques to control the initial relative humidity over oxide/salt mixtures have been developed using cerium oxide as a surrogate for plutonium oxide. Such control is required to validate certain assumptions in the Department of Energy Standard DOE-STD-3013, and to provide essential information to support field surveillance at the storage sites for excess plutonium oxides. Concern over the validity of the assumption that corrosion induced degradation in 3013 containers could be controlled by assuring that the moisture content of any stored oxide/salt mixture was below 0.5 w t% arose when stress corrosion cracks were found in test samples exposed at roommore » temperature to plutonium oxide/salt mixtures having a moisture content only marginally above 0.5 wt %. Additionally, analysis of the stress corrosion cracking observations suggests that the initial relative humidity over the oxide/salt mixture may play a major role in the cracking process. The investigations summarized in this report provide the procedures necessary to control the initial relative humidity to selected values within the range of 16 to 50% by controlling the loading relative humidity (18 to 60%) and the oxide/salt mixture water content (0.05 to 0.45 wt %). The studies also demonstrated that the initial relative humidity may be estimated by calculations using software EQ3/6. Cerium oxide/salt mixtures were used in this study because qualification tests with non-radioactive materials will reduce costs while increasing the breadth of the test programs required to support field surveillances of stored 3013 containers.« less