The plateout distribution of gamma-emitting nuclides in the primary circuit of the Peach Bottom HTGR at end-of-life has been determined by in situ gamma scanning. The specific activity was mapped by scanning the accessible ducting at 12 locations with a Ge(Li) detector and by axially traversing 79 steam generator tubes with travelling CdTe detectors from the water side. Following destructive removal of trepan samples, a travelling intrinsic germanium detector was inserted sequentially into two vertical ducts and the plateout mapped along 6-m runs of ducting. Calibration measurements on mockups allowed reduction of the spectra to specific activity. The measured plateout …
continued below
Publisher Info:
General Atomic Co., San Diego, CA (USA)
Place of Publication:
San Diego, California
Provided By
UNT Libraries Government Documents Department
Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.
Descriptive information to help identify this article.
Follow the links below to find similar items on the Digital Library.
Description
The plateout distribution of gamma-emitting nuclides in the primary circuit of the Peach Bottom HTGR at end-of-life has been determined by in situ gamma scanning. The specific activity was mapped by scanning the accessible ducting at 12 locations with a Ge(Li) detector and by axially traversing 79 steam generator tubes with travelling CdTe detectors from the water side. Following destructive removal of trepan samples, a travelling intrinsic germanium detector was inserted sequentially into two vertical ducts and the plateout mapped along 6-m runs of ducting. Calibration measurements on mockups allowed reduction of the spectra to specific activity. The measured plateout profiles were in excellent agreement with those predicted with the PAD code. The dominant gamma emitters were Cs-137 and Cs-134; their relative distributions were similar. Little local structure to the plateout in the ducts was observed, only a gradual decrease in specific activity in the direction of coolant flow. In the steam generator, a significant entrance effect was observed in the superheater section; the activity was highest where the inlet jet impinged and lowest at the ends of the bundle despite the presence of a flow baffle. The effect damped out with penetration into the bundle, and the axial profile was uniform at the economizer exit. When the axial profiles are averaged, the specific activity decreased monotonically across the tube bundle. Cesium deposition throughout the circuit was apparently mass transfer controlled with the exception of the hot duct where the accumulation was limited by the high temperatures. The superheater entrance effect probably resulted from the maldistribution of coolant flow. The profiles suggest that cesium was transported primarily in atomic form despite the presence of carbonaceous dust. Finally, the measured plateout distribution verifies the reference methodology used to make such predictions for large HTGR design.
This article is part of the following collection of related materials.
Office of Scientific & Technical Information Technical Reports
Reports, articles and other documents harvested from the Office of Scientific and Technical Information.
Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.
Hanson, D. L.; Baldwin, N. L. & Selph, W. E.Gamma scanning the primary circuit of the Peach Bottom HTGR,
article,
October 31, 1976;
San Diego, California.
(https://digital.library.unt.edu/ark:/67531/metadc1450015/:
accessed July 16, 2024),
University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.
