
North Korea's Nuclear Program: The Reasons for Concern

There are three primary reasons for concern about the
DPRK's nuclear program. The first relates to the DPRK's
continued defiance of IAEA safeguards, its March 1993
withdrawal from the NPT (which, although suspended, was
never renounced entirely), and its subsequent withdrawal
from the IAEA. The DPRK now claims a "unique status" under
the NPT as a nation that has withdrawn and then suspended
that withdrawal. The DPRK claims its unique status allows
it to accept some IAEA inspections and safeguards while
rejecting others. Such unique status is neither claimed nor
recognized by any other nation [6].

Second, the DPRK's history of military aggression and
terrorism, its enormous conventional military capability,
and its record as a major exporter of missiles and other
conventional arms to the Middle East all provide a context
that makes its nuclear ambitions particularly threatening.

Third, the DPRK's choices of technologies for its nuclear
program make no economic or technical sense for a nuclear
power program, but are perfectly logical for a nuclear
weapons production effort. Natural uranium-fueled reactors
similar to the DPRK's were the technology of choice for
weapons-grade plutonium production in each of the five
declared nuclear weapons states [7]. Moreover, the DPRK's
Yongbyon reactor, operational since 1986, was not connected
to electrical generators or power transmission lines until
1992, just prior to the third IAEA inspection [8].

Most significant, a civilian nuclear power program on the
small scale of the DPRK's would have no sensible use for a
large plutonium reprocessing plant such as that at
Yongbyon. The DPRK's justifications for this plant (future
development of breeder reactors and waste management) ring
hollow, but are legitimized under the terms of the NPT and
IAEA safeguards [9]. They also parallel those of Japan,
whose extensive plutonium program has the approval of the
United States (although it should be stressed that Japan
accepts full IAEA safeguards, while the DPRK does not).
This inconsistency in U.S. policy further complicates
non-proliferation diplomacy with the DPRK.

Several other developments suggest that the DPRK seeks to
acquire a nuclear weapons capability. In December 1992 a
planeload of 36 Russian scientists was stopped by Russian
authorities on the runway in Moscow, just before taking off
for Pyongyang. According to security analyst Andrew Mack,
"although the Sunday Times report referred to 'nuclear'
scientists, Russian Security Minister Vicktor Barranikov
later stated that the scientists had in fact been hired "to
build missile complexes capable of delivering nuclear
warheads'" [10]. There have also been unconfirmed reports
that 56 kilograms of plutonium may have been smuggled out
of the former Soviet Union to North Korea [11]. In the last
few years U.S. intelligence satellites have detected more
than 70 pits in the sand banks of the Kuryong River near
the Yongbyon nuclear facility, suggesting evidence of
testing of the non-nuclear elements of the triggering
package for an implosion-type nuclear weapon. It is
unclear, however, why the DPRK would choose to conduct such
tests in the open and near a nuclear research facility,
where they would be bound to generate suspicion [8].

Plutonium and Nuclear Weapons

Plutonium is one of two fissile materials, the other being
highly enriched uranium (HEU), either one of which can
comprise the essential ingredient for a nuclear weapon.
When compressed into a critical mass, these radioactive
materials fuel the fast chain reaction that produces a
nuclear explosion. As little as four kilograms of
plutonium, an amount about the size of an orange, is enough
to produce a nuclear explosion [12].

Plutonium is not found in nature, but is produced in
nuclear reactors when neutrons freed by the controlled
chain reaction collide with and are absorbed by atoms of
uranium-238 to create plutonium-239. When used (or "spent")
uranium fuel is removed from a nuclear reactor, it can be
chemically processed to separate out the plutonium, which
can then be used as fuel for nuclear reactors or for
nuclear bombs. The IAEA is concerned that some or all of
the fuel previously removed by the DPRK from its
gas-graphite reactor at Yongbyon might have been diverted
from safeguards and reprocessed to separate plutonium for
use in nuclear weapons [13].

The IAEA analyzed plutonium samples provided by the DPRK.
By analyzing the radioactive isotopes present in this
plutonium, as well as samples from the hot cells (process
stages of the Yongbyon reprocessing plant) where this
plutonium had been separated from spent fuel, the IAEA was
able to estimate when the reprocessing took place. The DPRK
claims it reprocessed only a few damaged fuel rods in 1989.
The IAEA's isotopic analysis indicated that reprocessing
had to have occurred on at least three separate occasions
in 1989, 1990, and 1991, at the Yongbyon facility [14].
This led the IAEA to suspect that the DPRK may have removed
more fuel in 1989 than it had declared, reprocessed it, and
hidden the separated plutonium and reprocessing waste from
the IAEA.

Suspicion that the DPRK was hiding undeclared reprocessing
waste triggered the IAEA's insistence on special
inspections at two sites in 1993. This request was refused
in March 1993, which marked the beginning of the crisis
that led to the DPRK's withdrawal from the NPT.

In early 1992, the Soviet press quoted a KGB document
reporting that the DPRK had already manufactured two
nuclear-weapon triggering devices [15]. U.S. intelligence
believes that the DPRK may already have separated enough
plutonium for at least one bomb [16]. The largest estimate
is from Dr. Taewoo Kim, president of the Institute for
Peace Strategy in South Korea, who contends that the DPRK
might possess enough separated plutonium for up to 14 bombs
[17]. In July 1994 a defector who claimed to be the
son-in-law of the DPRK's prime minister alleged that North
Korea had constructed five nuclear warheads and was working
on an additional five, as well as the technology to mount
the warheads on ballistic missile delivery systems [18,19].
South Korea and the IAEA later rejected the defector's
story as not being credible.

The technical community widely accepts the premise that the
principal obstacle to building nuclear weapons today is
obtaining the essential nuclear material -- separated
plutonium or highly enriched uranium. A nation with a
nuclear infrastructure such as the DPRK is assumed to be
able to build at least World War II-type nuclear weapons,
although not necessarily more advanced designs that could
be delivered by missiles.

What Might the DPRK be Hiding?

The IAEA wants to conduct special inspections at two sites
near the Yongbyon facility. The DPRK refuses even to
discuss the possibility of such inspections. The IAEA also
had hoped to take random samples from some 300 of the 8,000
fuel rods removed from the gas graphite reactor at
Yongbyon. This is important so that the IAEA can determine
how much plutonium is contained in the spent fuel. Sampling
could also assist the IAEA in deter mining how long the
fuel was in the reactor, which would help determine whether
an entire core (or a partial one) was removed during the
1989 shutdown. The IAEA has stated, however, that any
chance to answer that question was lost when the DPRK
defueled the reactor without setting aside fuel rods
specified by the Agency [20]. The DPRK will not allow the
IAEA to take samples from the fuel rods which remain under
IAEA safeguards at the moment. Moreover, there is now no
way to determine where the fuel rods were located inside
the reactor before they were removed -- information
important for interpreting amounts of plutonium found in
the spent fuel.

Despite its threatened withdrawal from the NPT and its
actual withdrawal from the IAEA, so far the DPRK has
allowed IAEA inspectors to remain [21] and as long as they
do, it should be possible to confirm that no additional
fuel is being removed to the reprocessing plant for
extraction of weapons-usable plutonium. If these
inspections continue, the effect will be to "cap" at least
this element of the DPRK's suspected nuclear weapons
program.

In addition to plutonium, nuclear bombs can be made from
highly enriched uranium (HEU). HEU for weapons usually
consists of 90% or more U-235, the isotope that sustains
the chain reaction in both nuclear reactors and nuclear
bombs. Because natural uranium contains less than 1% U-235,
an expensive, technically complex process known as
enrichment is required to separate the U-235 from the most
abundant isotope, U-238. Most of the undeclared nuclear
facilities discovered in Iraq after the Gulf War were part
of a large-scale uranium enrichment program.

No such facilities are publicly known to exist in the DPRK.
But unconfirmed South Korean reports indicate that a
uranium enrichment facility was established in the
mid-1980s near Pyongsan, about 95 kilometers southeast of
Pyongyang (Fig 1) [8]. These reports do not indicate either
the capacity or enrichment technology of such a plant, but
if confirmed the DPRK could possess an unsafeguarded source
of weapons-usable material in addition to its reprocessing
plant. The DPRK's expertise in tunneling technology also
raises the possibility that it could build additional
reactors and reprocessing plants, as well as enrichment
facilities, underground, without these facilities being
detected by either the IAEA or Western intelligence [23].

