Environmental Engineering Reference
In-Depth Information
power cables that had resulted in plant shutdowns and unusual transients. After
evaluating licensee responses, the NRC summarized the current plant circum-
stances with respect to cable condition monitoring in its recommendations:
'Plants undergoing license renewal have agreed to a cable testing program for
the extended period of plant operation for a limited number of cables that are
within the scope of license renewal, but only a few have established a cable test-
ing program for the current operating period. The data… show an increasing
trend of cable failures. These cables are failing within the plants' 40-year licens-
ing periods… Licensees have identifi ed failed cables and declining insulation
resistance properties through current testing practices; however, licensees have
also reported that some failures may have occurred before the failed condition
was discovered … The 10 CFR Part 50 regulations require licensees to assess
the condition of their components, to monitor the performance or condition …
in a manner suffi cient to provide reasonable assurance that they are capable of
fulfi lling their intended functions, and to establish a test program to ensure that
all testing required to demonstrate that components will perform satisfactorily
in service is identifi ed and performed' (AMS Corp., 2010).
Regulators are increasingly urging that cable ageing be taken into account
to ensure that plants continue to operate safely throughout the remainder
of their original licenses and during any extended operation (AMS Corp.,
2011). For example, the U.S. NRC published the Regulatory Guide 1.218 in
April 2012 to describe the technique that the NRC staff considers accept-
able for monitoring the performance of electrical cables that are important
to safety (U.S. NRC, 2012). The title of this regulatory guide is 'Condition
Monitoring Techniques for Electric Cables Used in Nuclear Power Plants'.
6.6 Sources of further information
Cable ageing and condition monitoring have been the subject of numerous
research and development (R&D) projects, reports, and standards produced
by the worldwide nuclear power industry. For example, in the mid-1990s,
the International Atomic Energy Agency (IAEA) produced one of the fi rst
documents (known as TECDOC 1188) on cable degradation, ageing, and
testing techniques. In the meantime, the Electric Power Research Institute
(EPRI) conducted a number of research projects on this subject and has
published a number of reports that are available to EPRI member utili-
ties. Beginning in 2007, the International Electrotechnical Commission
(IEC) began to prepare new standards, technical reports, and guidelines on
the subject of cable ageing, condition monitoring, and testing techniques.
Recently, the Nuclear Energy Agency (NEA) in Paris has taken up the sub-
ject and has already issued a comprehensive report on ageing of nuclear
power plant components, systems, and structures (SSCs) including cables.
The NRC ' s offi ce of research has been evaluating the cable ageing issue and
has drafted a regulatory guide entitled 'Condition Monitoring Program for
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