skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Gamma-ray imaging assay of cells 3-5 of the east cell line in the 235-F plutonium fuel form facility

Abstract

In August and September, 2016, scientists from the Savannah River National Laboratory (SRNL) took a series of gamma-ray imaging measurements through the cell windows in front of Cells 3-5 on the east line of the Plutonium Fuel Form (PuFF) Facility using an electrically cooled, high-purity germanium detector. A Germanium Gamma Ray Imager (GeGI) was utilized since it allowed for the location from which the radiation was being emitted to be identified by incoming gamma-ray energy. This measurement technique provided a tool which allowed for the relative concentration of Pu-238 to be mapped throughout each cell. The mapping and new assay data were then used to update the model used in an assay discussed in a 2014 report (SRNL-STI-2014-00629) and to calculate a more accurate value for the holdup in each of the cells [1]. Note that the mapping and new assay data did not replace the previous assay data in the model. Rather, the mapping and new assay data provided additional details on source distribution, which supplemented the previous assay data.

Authors:
 [1];  [1];  [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:
1361663
Report Number(s):
SRNL-STI-2017-00177
DOE Contract Number:
AC09-08SR22470
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY

Citation Formats

Brand, A. D., Aucott, T. J., and Diprete, D. P. Gamma-ray imaging assay of cells 3-5 of the east cell line in the 235-F plutonium fuel form facility. United States: N. p., 2017. Web. doi:10.2172/1361663.
Brand, A. D., Aucott, T. J., & Diprete, D. P. Gamma-ray imaging assay of cells 3-5 of the east cell line in the 235-F plutonium fuel form facility. United States. doi:10.2172/1361663.
Brand, A. D., Aucott, T. J., and Diprete, D. P. Sat . "Gamma-ray imaging assay of cells 3-5 of the east cell line in the 235-F plutonium fuel form facility". United States. doi:10.2172/1361663. https://www.osti.gov/servlets/purl/1361663.
@article{osti_1361663,
title = {Gamma-ray imaging assay of cells 3-5 of the east cell line in the 235-F plutonium fuel form facility},
author = {Brand, A. D. and Aucott, T. J. and Diprete, D. P.},
abstractNote = {In August and September, 2016, scientists from the Savannah River National Laboratory (SRNL) took a series of gamma-ray imaging measurements through the cell windows in front of Cells 3-5 on the east line of the Plutonium Fuel Form (PuFF) Facility using an electrically cooled, high-purity germanium detector. A Germanium Gamma Ray Imager (GeGI) was utilized since it allowed for the location from which the radiation was being emitted to be identified by incoming gamma-ray energy. This measurement technique provided a tool which allowed for the relative concentration of Pu-238 to be mapped throughout each cell. The mapping and new assay data were then used to update the model used in an assay discussed in a 2014 report (SRNL-STI-2014-00629) and to calculate a more accurate value for the holdup in each of the cells [1]. Note that the mapping and new assay data did not replace the previous assay data in the model. Rather, the mapping and new assay data provided additional details on source distribution, which supplemented the previous assay data.},
doi = {10.2172/1361663},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}

Technical Report:

Save / Share:
  • On September 17th -19th , 2013, scientists from SRNL took a series of in-situ gamma-ray measurements in the maintenance trench beneath Cells 1-5 on the east line of the PuFF facility using a well-collimated, high-purity germanium detector. The cell interiors were assayed along with the furnaces and storage coolers that protrude beneath the cells. The detector efficiency was estimated using a combination of MCNP simulations and empirical measurements. Data analysis was performed using three gamma-rays emitted by Pu-238 (99.85 keV, 152.7 keV, and 766.4 keV) providing three independent estimates of the mass of Pu-238 holdup in each of the cells.more » The weighted mean of these three results was used as the best estimate of Pu-238 holdup in the East Cell Line of PuFF. The results of the assay measurements are found in the table on the following page along with the results from the scoping assay performed in 2006. All uncertainties in this table (as well as the rest of the report) are reported at 1σ. Summing the assay results and treating MDAs as M 238Pu= 0 ± MDA, the total holdup in the East Cell Line was 240 ± 40 grams. This result is 100 grams lower than the previous estimate, a 0.55σ difference. The uncertainty in the Pu-238 holdup is also reduced substantially relative to the 2006 scoping assay. However, the current assay results are in agreement with the 2006 scoping assay results due to the large uncertainty associated with the 2006 scoping assays. The current assay results support the conclusion that the 2006 results bound the Pu-238 mass in Cells 1-5. These results should be considered preliminary since additional measurements of the East Cell line are scheduled for 2017 and 2018. Those measurements will provide detailed information about the distribution of Pu-238 in the cells to be used to refine the results of the current assay.« less
  • On August 29th, 2013, scientists from SRNL took a series of in-situ gamma-ray measurements in the maintenance trench beneath Cells 6-9 on the west line of the PuFF facility using an uncollimated, highpurity germanium detector. The detector efficiency was estimated using a combination of MCNP simulations and empirical measurements. Data analysis was performed using three gamma-rays emitted by Pu-238 (99.85 keV, 152.7 keV, and 766.4 keV) providing three independent estimates of the mass of Pu-238 holdup in each of the cells. The weighted mean of these three results was used as the best estimate of Pu-238 holdup in the Westmore » Cell Line of PuFF. The results of the assay measurements are found in the table below along with the results from the scoping assay performed in 2006. All uncertainties in this table (as well as the rest of the report) are given as 1σ. The total holdup in the West Cell Line was 2.4 ± 0.7 grams. This result is 0.6 g higher than the previous estimate, a 0.4σ difference.« less
  • In November and December 2015, scientists from SRNL took a series of in-situ gamma-ray measurements through the windows in front of Cells 6-9 on the west line of the PuFF facility using a shielded, 120% high-purity germanium detector. The detector efficiency was estimated using a combination of MCNP simulations and empirical measurements. Where possible, the distribution of the Pu-238 in the cells was determined using the Germanium Gamma-ray Imager (GeGI). This distribution was then fed into the MCNP model to quantify the Pu-238 in each cell. Data analysis was performed using three gamma rays emitted by Pu-238 (99.85 keV, 152.7more » keV, and 766.4 keV) providing three independent estimates of the mass of Pu-238 holdup in each of the cells.« less
  • Savannah River National Laboratory (SRNL) Nuclear Measurements (L4120) was tasked with performing enhanced characterization of the holdup in the PuFF shielded cells. Assays were performed in accordance with L16.1-ADS-2460 using two high-resolution gamma-ray detectors. The first detector, an In Situ Object Counting System (ISOCS)-characterized detector, was used in conjunction with the ISOCS Geometry Composer software to quantify grams of holdup. The second detector, a Germanium Gamma-ray Imager (GeGI), was used to visualize the location and relative intensity of the holdup in the cells. Carts and collimators were specially designed to perform optimum assays of the cells. Thick, pencil-beam tungsten collimatorsmore » were fabricated to allow for extremely precise targeting of items of interest inside the cells. Carts were designed with a wide range of motion to position and align the detectors. A total of 24 measurements were made, each typically 24 hours or longer to provide sufficient statistical precision. This report presents the results of the enhanced characterization for cells 1 and 2. The measured gram values agree very well with results from the 2014 study. In addition, images were created using both the 2014 data and the new GeGI data. The GeGI images of the cells walls reveal significant Pu-238 holdup on the surface of the walls in cells 1 and 2. Additionally, holdup is visible in the two pass-throughs from cell 1 to the wing cabinets. This report documents the final element (exterior measurements coupled with gamma-ray imaging and modeling) of the enhanced characterization of cells 1-5 (East Cell Line).« less
  • This study described the general safeguards characteristics of a material measurement system and then describes typical accounting systems for a fuel reprocessing plant, a plutonium nitrate to oxide conversion facility, a LWR mixed oxide fuel fabrication facility, and a high-enriched uranium HTGR fuels plant. These facilities are commercial size, envisioned to be operating in the mid-1980s. Present facilities tend to have large static inventories of material whereas future facilities will have a high material throughput. Systematic errors will pose the greatest limit on measurement systems in future facilities. Recommendations are given for the licensing review process for material accounting performance,more » the capability of measurement systems and regulations governing cumulative LEMUF and series of MUFs. Present regulations and the recommendations should result in improved material accounting in future facilities. Improvements specific to a particular facility were also identified. The recommendations should greatly improve the material accounting characteristics of future plutonium and high-enriched uranium processing facilities. Benefits of an improved material accounting system are compared with the costs of the improvements. The requirement for a formal quarterly inventory over the separations area of a reprocessing plant results in an annual lost production cost of $25M. This high penalty prevents reducing the formal inventory requirement from the present semiannual regulatory requirement. In all other cases, the cost-benefit relationship of the improvements is favorable. 8 fig., 53 tables. (DLC)« less