Environmental Engineering Reference
In-Depth Information
9
Materials-related problems faced by light
water reactor (LWR) operators and
corresponding research needs
S. RAY and E. LAHODA , Westinghouse Electric
Company LLC, USA
DOI : 10.1533/9780857097453.3.385
Abstract : This chapter provides background on current materials-related
problems faced by the nuclear industry. These issues have become more
important as the current fl eet of nuclear plants ages and as life extensions
of 20 years each are added onto the current 40 year life. Materials issues
requiring research and development are presented in terms of the fuel,
the primary boundary, the containment and other general issues.
Key words : nuclear, power plant, industry, materials, issues, fuel, rods,
cladding, containment, primary, secondary, corrosion, cracking, buried,
pipe, wiring, concrete, steel.
9.1
Introduction
As the light water reactor (LWR) nuclear fl eet reaches and surpasses the
original 40 year lifespan that it was licensed for and embarks on its next
20 years with visions of yet another 20 years beyond that, the need increases
for a scientifi c underpinning of the understanding of the degradation of
materials in a nuclear environment. The need to generate this scientifi c
underpinning becomes more compelling when one considers that the orig-
inal 40 year life had no scientifi c basis (INL, 2009) and that the materials
designs were not based on irradiated materials in real life chemistry con-
ditions (Majumdar, 2011). There are indeed many existing models and
correlations for determining what may happen as materials in a nuclear
environment age, but most are based purely on empirical data. The ability
to extrapolate these models is under question by the industry and the NRC,
which will not grant licenses based on extrapolated models. Far too often,
researchers have discovered unexpected effects, both good and bad, which
should not have occurred based on extrapolation of models.
This chapter focuses on the materials in a nuclear system from the inside
out of a nuclear plant. First the initial fi ssion boundary of the fuel (Fig. 9.1),
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