Data integrity review of Three Mile Island Unit 2. Hydrogen burn data. Volume 3

Abstract

About 10 hours after the March 28, 1979 loss-of-coolant accident began at Three Mile Island Unit 2 (TMI-2), a hydrogen burn occurred inside the Reactor Building. This report reviews and presents data from 16 channels of resistance temperature detectors (RTDs), 2 steam generator pressure transmitters, 16 Reactor Building pressure switches, 2 channels of Reactor Building pressure measurements, and measurements of Reactor Building hydrogen, oxygen, and nitrogen concentrations with regard to their usefulness for determining the extent of the burn and the resulting pressure and temperature excursions inside the building.

TMI-2 - A Case Study for PWR Instrumentation Performance during a Severe Accident

“…However, because of their slow sampling rate, recorded peak temperatures from the RTDs were less than 93°C, which was much lower than the 650°C estimates obtained assuming peak pressures measured in the reactor building. 84,83 Physical damage to organic materials substantiated that temperatures exceeded 232°C, which was also much higher than available data from the RTDs. Hence, data were evaluated as "Qualified" for all times except at temperature peaks.…”

“…Several sources of data were available to estimate the reactor building pressure during the TMI-2 accident. 83,84 There were two pressure transmitters associated with the strip chart recorder for which data were recorded continuously, and six reactor building pressure switches. In addition, pressure transmitters measured the reactor building pressure as a steam generator reference pressure, and these data were recorded on the reactimeter every 3 seconds.…”

Qualification of Daiichi Units 1, 2, and 3 Data for Severe Accident Evaluations - Process and Illustrative Examples from Prior TMI-2 Evaluations

“…However, because of their slow sampling rate, recorded peak temperatures from the RTDs were less than 90°C, which was much lower than the 650°C estimates obtained from engineering calculations based on peak pressures measured in the reactor building. 24,27 Physical damage to organic materials substantiated that containment temperatures exceeded 232°C, which was also much higher than available data from the RTDs. Hence, data were categorized as "Qualified" for all times except at the time when peak temperature were estimated to have occurred.…”

“…Several sources of data were available to estimate the reactor building pressure during the TMI-2 accident. 24,27 As described within this section, evaluations included analyzing data collected during and after the accident, observations of damage to materials within the containment, comparisons made with data obtained from other sensors within the containment, and engineering analyses performed using such data.…”

Assessment of extent and degree of thermal damage to polymeric materials in the Three Mile Island Unit 2 reactor building. Volume VI

“…Response properties of the exemplar materials were measured in a thermal gravimetric analyzer (TGA) to ascertain the temperature range of thermal degradation and weight-loss rates. Figures 7,8, and 9 show TGA patterns for three of these materials:…”