Assessment of N-Reactor Zircaloy-2 pressure tube corrosion and hydriding trends
Corrosion and hydriding of N-Reactor Zircaloy-2 pressure tubes have been monitored by periodic removal of tubes for destructive examination. To date, nine tubes have been examined, representing exposures from 1400 to 14,500 MWd (439 to 3860 operating days). Oxide profiles on tube inside (water side) surfaces generally follow the flux profile, indicating radiation enhancement of corrosion. Maximum oxide thickness increases with increasing exposure, reaching approx.50 ..mu..m (0.002 in.) in the most recently examined tubes. Oxides on tube outside (gas side) surfaces are much thinner (up to 15 ..mu..m) and do not consistently relate to the flux profile. Two zones of accelerated hydriding have been identified along the tube lengths: (1) in upstream, out-of-flux tube sections; and (2) in the flux zone, directly related to the corresponding oxide profiles. In high exposure tubes, peak in-flux hydrogen concentrations exceed peak values at out-of-flux locations. Models have been developed to project future oxide and hydriding trends. Peak oxidation of the inside surface is expected to continue at a rate of 0.016 ..mu..m per effective full power day (EFPD) or 4.0 ..mu..m per 1000 MWd. The peak axial hydrogen concentration (wall average) is expected to increase at the rate of 21 ppM per 1000 MWd. The high hydrogen concentrations near the tube inside surface are expected to reach levels of 1000 to 2000 ppM (over 20% of the wall) in less than 6000 MWd (less than 5 y).
- Research Organization:
- UNC Nuclear Industries, Inc., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01857
- OSTI ID:
- 6198648
- Report Number(s):
- UNI-3146-Rev.1; ON: DE87007103
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
220700* -- Nuclear Reactor Technology-- Plutonium & Isotope Production Reactors
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
360106 -- Metals & Alloys-- Radiation Effects
ALLOYS
CHEMICAL REACTIONS
CHROMIUM ADDITIONS
CHROMIUM ALLOYS
CORROSION
ENRICHED URANIUM REACTORS
GRAPHITE MODERATED REACTORS
HYDRIDATION
IRON ADDITIONS
IRON ALLOYS
LWGR TYPE REACTORS
MATHEMATICAL MODELS
N-REACTOR
PHYSICAL RADIATION EFFECTS
PLUTONIUM PRODUCTION REACTORS
POWER REACTORS
PRESSURE TUBES
PRODUCTION REACTORS
RADIATION EFFECTS
REACTORS
TIN ALLOYS
TUBES
WATER COOLED REACTORS
ZIRCALOY
ZIRCALOY 2
ZIRCONIUM ALLOYS
ZIRCONIUM BASE ALLOYS