Ultrasonic Testing of Replacement Pipe for Nuclear Reactor
The Hope Creek nuclear reactor, located in Lower Alloways Creek in
south New Jersey, was shut down on March 27, 2005 to investigate a radioactive
steam leak. Hope Creek is one of three reactors owned by Public Service
Enterprise Group Inc. (PSEG) at the Salem Nuclear Generating Station,
which provides electricity to over a million New Jersey customers.
According to PSEG, the leak occurred in the facility’s innermost
containment area and posed no threat to plant employees. The shutdown
allowed workers to look in the dry well and under the reactor core for
the source of the small but growing amount of radioactive steam since
February.
The workers found steam escaping from a broken weld in a pipe that is
about a foot long and about 4 inches in diameter. This pipe is connected
to a 28-inch diameter pipe that is part of the plant’s cooling
system and connects several feet away to a 20-foot-high recirculating
cooling-water pump. The pipes were installed at least 20 years ago,
before the plant began operating in 1986.
The recirculating cooling-water pumps have a shaft that vibrates when
the plant is running at full capacity. PSEG attributed the cracked weld
to vibrations from normal plant operations.
Plant workers have replaced the 4-inch diameter cracked pipe with a
shorter piece of seamless pipe to eliminate the weld. The same change
was made on an identical pipe for a second recirculation pump to eliminate
the weld as a precaution.
The replacement pipe was air freighted to Laboratory Testing Inc. from
the manufacturer as a rush order for ultrasonic testing. When testing
was completed, the pipe was shipped directly to the Hope Creek plant.
The ultrasonic testing looked for internal flaws and discontinuities in the wall
of the pipe.
The Nuclear Regulatory Commission gave approval to restart the Hope
Creek plant 12 days after shutdown, upon reviewing PSEG’s report
on the cause of the leak and the company’s repairs made in response
to the problem.