
Potential Nuclear Consequences of a Conventional Korean War

A conventional war on the Korean peninsula could have major
nuclear consequences in the form of radioactive releases if
reactors and other nuclear plants were targeted and
destroyed. This danger is not widely recognized, but is
known to be a major factor inhibiting a more aggressive
U.S. response to the DPRK's defiance of inter national
nuclear inspections and other NPT obligations. The DPRK's
reactors presumably could be bombed in a way to collapse
upon themselves and cause minimal radioactive releases --
as was the case when allied forces destroyed Iraq's
research reactors during the Gulf War. (The DPRK has two
larger power reactors under construction, but like the
unfinished Iraqi reactor destroyed by Israel in 1981, they
would not give off radioactive releases if bombed.) The
Yongbyon reprocessing plant conceivably could be bombed in
a way to minimize releases if no spent fuel is present in
the plant and if high-level reprocessing waste tanks are
not hit. Such a "benign" or "surgical" strike, however, may
not be possible in practice.

In South Korea there are nine large operating nuclear power
reactors located 125 to 250 miles from the North Korean
border [23], any one of which, if destroyed in an attack,
could cause Chernobyl-type effects. These reactors are
clustered as many as four to a site. Thus, the toxic
effects could be compounded if more than one were destroyed
in an attack.

Reactors, despite their massive size, are vulnerable to
conventional explosions -- including truck bombs. The U.S.
Nuclear Regulatory Commission (NRC) recently ordered
nuclear utilities to build barriers against truck-bomb
attack, as the result of two events last year -- the
truck-bombing of the World Trade Center and a security
penetration at the remaining nuclear power plant at Three
Mile Island by an intruder who crashed his car into the
turbine building of the plant [24]. Although a reactor
cannot explode like a nuclear weapon, a large conventional
explosion could destroy a reactor's redundant safety
systems, cutting off water that cools the core and causing
the radioactive fuel to melt down. There could be similar
consequences if a plant were "decapitated" by destroying
its control room.

A military attack against a reactor could break open the
containment dome and cause maximum dispersal of the
radioactive poisons in the core. Such a catastrophic
release could affect 2,000 to 5,000 square miles and cause
hundreds of thousands of excess deaths over subsequent
years in densely populated countries such as South Korea
and Japan. Although early fatalities are probable, most
deaths would likely be caused by late cancers. Over time
there could also be severe genetic effects [25].

The DPRK's Scud B missile has a range of 175 miles; the
Scud C's range is 375 miles. The No-dong-1 missile, now
under development and test-fired last year into the Sea of
Japan, has a range of at least 625 miles and two other
missiles are under development with ranges exceeding 1,200
miles [26]. All these missiles are notoriously inaccurate
and might not come close enough to a reactor to severely
damage it with a conventional warhead. Reactors in South
Korea and Japan, however, are within easy range of North
Korean aircraft, and South Korea's reactors would be
vulnerable to North Korean artillery and commando attack in
a war. South Korea's reactors deliver a total of 7,600
megawatts of electrical power (MWe) and range in size from
650 to 950 MWe each (see Figure 2). Six of them are 950 MWe
[23]. The core of a 1,000 megawatt reactor contains some 5
million curies of strontium-90 and 6 million curies of
cesium-137 -- two of the deadliest and longest-lived
radioactive poisons. By comparison, a 20-kiloton,
Hiroshima-scale bomb gives off 2,200 curies of strontium-90
and 3,200 curies of cesium-137. Expressed another way, the
strontium and cesium contained in the core of a single
1,000 megawatt nuclear power reactor is equivalent to the
strontium and cesium fallout created by 70 to 90 megatons
of nuclear explosions, or 350-450 nuclear weapons, each
with a yield of 200 kilotons [27].

In addition to strontium and cesium, nuclear reactors
produce large amounts of plutonium -- the deadliest
radioactive element. The Nagasaki bomb contained about 6
kilograms of plutonium (about 13 pounds), of which only
about 1 kilogram was consumed by fission, leaving 5
kilograms dispersed in the fallout. By comparison, a
1,000-megawatt reactor contains about 500 kilograms of
plutonium in its core. Thus, a nuclear power reactor
contains plutonium comparable to what would be dispersed by
100 fission weapons [27]. A few micrograms of plutonium,
about the size of a pollen grain, can cause cancer if
inhaled and caught in the lung or if absorbed elsewhere in
the body after being ingested or passing through a cut or
wound.

Even if war on the Korean peninsula were known to be
imminent, South Korea (which is dependent on nuclear power
for 40% of its electricity) could not shut down its
reactors fast enough to prevent major releases in the event
of an attack. The "residual heat" in the core of an
operating reactor is so great that a 1,000-megawatt reactor
would have to be shut down for several weeks for the heat
to dissipate sufficiently to avoid a meltdown in case of
attack. An attack could also cause cooling water to drain
from the spent-fuel storage pond on the plant site, and
there could be additional releases from melted fuel.

Thus, the possible nuclear consequences of a conventional
war should be a major factor in considering any action that
could provoke a war on the Korean peninsula.

The Role of South Korean and Japanese Nuclear Programs in
the Crisis

The North Korean nuclear crisis is perpetuated by a
regional triangle of misperception and mistrust. Each of
the three regional actors (Japan, the DPRK, and South
Korea) suspects the other two of harboring military
intentions for plutonium. Each actor could become less
willing to forego its own plutonium option and, thus,
reinforce the fears of the other two.

The DPRK has repeatedly accused Japan of pursuing nuclear
weapons through its plutonium program. The accusation was
first made by the DPRK at an IAEA Board of Governors
meeting in the fall of 1991 [28]. The DPRK has pointed to
Japan's surplus of plutonium as indications of a bomb
program. The DPRK's Korean Central Broadcasting network
reported last year that "if the plutonium Japan has brought
in is for peaceful use, as the Japanese ruling circles
claim, the quantity they stockpile is too large, and they
need not bring it in such secrecy, hiding it from people's
eyes. Japan is scheming to stockpile enormous quantities of
plutonium to produce nuclear weapons massively at any time
it chooses " [29]. The DPRK's government-controlled press
also cited Japan's fast breeder reactor program (which in
fact pro duces weapons-grade plutonium) and sea shipments
of plutonium from Europe as proof that "the danger of
Japan's nuclear armament presents itself as a thing of the
present-day reality, not of a distant future" [30].

To some extent this is propaganda to divert attention from
and to justify the DPRK's own plutonium efforts.
Nonetheless, some of the DPRK's fear of a nuclear-armed
Japan could well be genuine, given Japan's close alliance
with the U.S. and the historical enmity between Japan and
Korea. At any rate, the DPRK has used Japan's plutonium
program to justify its own and has closely linked a halt in
Japan's plutonium program to the resolution of the nuclear
impasse on the Korean peninsula.

The DPRK has challenged the nonproliferation bona fides of
South Korea as well. Earlier this year, a North Korean
Foreign Ministry memorandum accused South Korea of
"stockpiling of plutonium through the PHWR [pressurized
heavy water reactor] and completion of a system for the
full-scale nuclear weapons development....It follows that
the PHWR operating in South Korea since 1983 has by now
produced potential plutonium enough to manufacture over 370
atomic bombs" [31]. This claim ignores the important
distinction between weapons-usable, separated plutonium and
plutonium that remains inaccessible for direct use in
weapons so long as it is contained in spent fuel, but it
does demonstrate the complex interaction of regional
nuclear programs.

South Korea, in turn, has expressed grave concerns about
the North's plutonium program. South Korea, acutely aware
that it could be the first target of any North Korean
nuclear weapons, has steadfastly insisted that the North
abandon reprocessing. Less widely publicized are South
Korean fears of Japan's plutonium program. An official in
the South Korean Ministry of Foreign Affairs stated in
December that "his government is keenly suspicious of
Japanese defense policies and Tokyo's accumulation of
plutonium stockpiles" [32].

Japan is greatly concerned about the North Korean program,
having gone so far as to hint at Japanese withdrawal from
the NPT if the North gets the bomb. Kabun Moto, at the time
Japanese Foreign Minister, stated in July 1993 that "there
is a clause in the NPT allowing withdrawal from the treaty.
If North Korea develops nuclear weapons and that becomes a
threat to Japan...if it comes down to a crunch, possessing
the will that 'we can do it' is important" [33]. Japanese
officials and nuclear industrialists have also made it
clear in direct communications with the Nuclear Control
Institute that they would not favor South Korea's acquiring
plutonium because of proliferation risks.

