Neutron dosimetry in the Three-Mile Island Unit 2 reactor cavity with solid-state track recorders

Conference · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5343294

Gold, R; Roberts, J H; Ruddy, F H; Preston, C C; McElroy, W N; Rao, S V; Greenborg, J; Fricke, V R

Solid-state track recorder (SSTR) neutron dosimetry has been conducted in the Three-Mile Island Unit 2 (TMI-2) reactor cavity (i.e., the annular gap between the pressure vessel and the biological shield) for nondestructive assessment of the fuel distribution. Two axial stringers were deployed in the annular gap with 17 SSTR dosimeters located on each stringer. SSTR experimental results reveal that neutron streaming, upward from the bottom of the reactor cavity region, dominates the observed neutron intensity. These absolute thermal neutron flux observations are consistent with the presence of a significant amount of fuel debris lying at the bottom of the reactor vessel. A conservative lower bound estimated from these SSTR data implies that at least 2 tonnes of fuel, which is roughly 4 fuel assemblies, is lying at the bottom of the vessel. The existence of significant neutron streaming also explains the high count rate observed with the source range monitors (SRMs) that are located in the TMI-2 reactor cavity.

• Research Organization: Hanford Engineering Development Lab., Richland, WA (USA); General Public Utilities Nuclear Corp., Middletown, PA (USA); Burns and Roe, Inc., Middletown, PA (USA)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC06-76FF02170
• OSTI ID: 5343294
• Report Number(s): HEDL-SA-3293; CONF-850933-1; ON: DE85018470
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210200* -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
ANNULAR SPACE
CONFIGURATION
DIELECTRIC TRACK DETECTORS
DOSIMETRY
ENRICHED URANIUM REACTORS
MEASURING INSTRUMENTS
NEUTRON DOSIMETRY
POWER REACTORS
PWR TYPE REACTORS
RADIATION DETECTORS
RADIATION STREAMING
REACTORS
SPACE
THERMAL REACTORS
THREE MILE ISLAND-2 REACTOR
WATER COOLED REACTORS
WATER MODERATED REACTORS