ＥＥＥ会議（米国のIndian Point原発の安全性）......................................................2003.9.20


かねてから安全性が問題になっている米国ニューヨーク州のIndian Point原発につい
ては、最近のスペースシャトル事故や今夏の大停電などの影響で、再び各方面から懸
念が高まっているようです。とくに「憂慮する科学者連合」（ＵＣＳ）などの反原
発、環境保護グループは、同原発炉心の緊急冷却システムは、事故時に破片によって
パイプが詰まり易いという危険性がある等の理由で、原子力規制委員会（ＮＲＣ）は
２００７年までにというような悠長なことではなく、なるべく早い時期の点検、修理
を命じるべきで、それまで同炉は運転停止すべきだと主張していますが、New York
Timesは本日の社説で、この主張を支持し、全米の他の原子炉についても同様の危険
性があるとしています。詳細は次のとおりです。--KK

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A New Risk at Reactors

Fragile space shuttles and a rickety electricity grid are not the only
complex technologies this nation is struggling to control. Critics
attempting to close the two nuclear reactors at Indian Point, north of New
York City, are now pointing to a risk that may endanger dozens of other
nuclear plants around the country as well. The risk appears to be slight,
but then so did the likelihood that foam insulation would destroy a space
shuttle.

The Union of Concerned Scientists, a nuclear watchdog group, and
Riverkeeper, an environmental organization, have petitioned the Nuclear
Regulatory Commission to shut down Indian Point because of an apparent flaw
in the emergency cooling systems, which are designed to keep the reactors
from melting down if a water pipe ruptures. The two groups contend that the
cooling systems would probably fail because the pumps they rely on would
become clogged by debris in an accident.

Such clogging could increase the risk of damage to a reactor core
substantially. Instead of expecting core damage once every 20,000 or 30,000
years, each reactor at Indian Point could expect a core-damage incident,
which increases the risk of radioactive materials' escaping, once every 400
years.

The potential for clogging emerged as a threat at boiling-water reactors in
the mid-1990's, forcing procedural changes and plant modifications. Now the
regulators are moving to reduce the risk at pressurized-water reactors as
well but will not complete the task until early 2007. Some regulators deem
the risk too slight to warrant greater urgency, and Entergy, the company
that operates Indian Point, says that any pipe rupture would generate too
little debris to clog its pumps. But the petitioners are right to question
whether the process is moving fast enough. They want either an immediate
shutdown of Indian Point or, failing that, modifications the next time the
reactors shut down for refueling.

There seems little justification for cracking down on Indian Point alone
when the same potential danger exists at most other pressurized-water
reactors. Any remedies should be applied broadly. And the regulators would
be wise to reassess whether they are moving fast enough to reduce a risk
that is acknowledged to be there.