Location: Pun’gang-chigu (分江地區), Yŏngbyŏn-kun (寧邊郡), North P’yŏng’an Province (平安北道), North Korea

Subordinate to: Nuclear Physics Research Institute (核物理硏究所), Yŏngbyŏn Nuclear Research Center (寧邊原子力硏究센터), General Department of Atomic Energy (原子力總局), Cabinet (內閣)

Size: 5MW(e), about 20-25MW(th)

Primary Function: Testing the capacity to generate electricity, production of electricity, and the production of plutonium

Description: North Korea’s 5MW(e) Experimental Reactor is a graphite-moderated, gas-cooled reactor with a thermal power range of 20-25MW. Construction of the reactor began in either 1979 or 1980, and was reportedly under construction by at least July 1980. The reactor was modeled after the British Calder Hall Gas Cooled Reactor that was first built in 1956. There were several advantages for North Korea to select this type of reactor design. The Calder Hall design has been unclassified and available for a number of years, and it uses natural uranium for its fuel, which is abundant in North Korea. Another advantage of this reactor design is the cooling system, which uses carbon dioxide, and therefore requires no heavy water. Furthermore, the reactor uses graphite, which is also available in North Korea, as a moderator. Another advantage to this type of reactor is that its spent fuel is a good source of weapon-grade plutonium for a nuclear weapons program. However, one problem with this type of reactor is that it is difficult to store the spent fuel for an extended period, or to dispose of it in a geological repository because the fuel cladding is magnesium, which breaks down when exposed to water or moisture.

The reactor went critical on 14 August 1985 before becoming operational in 1986. According to North Korea’s initial declaration, 5MW(e) Experimental Reactor was operated between 1986 and 1994. This reactor is of great concern because it may have been used to produce plutonium for North Korea’s suspected nuclear weapons program. The reactor was shut down for 71 days in 1989, about 30 days in 1990, and about 50 days in 1991. These periods provided an opportunity to discharge and reprocess the spent fuel. North Korea later reported to the IAEA that it reprocessed about 90 grams of plutonium from damaged spent fuel rods that were removed from the reactor in 1989, but no references were made to the reactor being shut down in 1990 or 1991. According to a South Korean report, US satellite imagery detected the shutdowns on all three occasions. The reactor was not being monitored by the IAEA because North Korea did not ratify a safeguards agreement until April 1992.

The IAEA inspected the 5MW(e) reactor and other nuclear facilities in Yŏngbyŏn following the Supreme People’s Assembly’s ratification of a safeguards agreement in April 1992. However, the IAEA discovered discrepancies in North Korea’s initial declaration, which led to the IAEA to request special ad hoc inspections, and to North Korea announcing its intention to withdraw from the Nuclear Non-Proliferation Treaty (NPT). In June 1993, Pyongyang announced that it was “suspending its withdrawal from the NPT” and began bilateral negotiations with Washington to resolve the impasse. North Korea allowed the batteries and film for cameras to be replaced, but not the return of IAEA inspectors to complete the inspections that began in May 1992.

In May and June 1994, North Korean technicians, without the supervision of IAEA inspectors, once again discharged the reactor’s spent fuel rods and placed them in the cooling pond. This action nearly led to a military confrontation with the United States, before former President Jimmy Carter’s trip to Pyongyang defused the crisis. Carter’s trip encouraged Kim Il Sung to accept some guidelines that resulted in the negotiation and conclusion of the Agreed Framework in October 1994. Under the terms of the agreement, the spent fuel rods that were unloaded in 1994 have now been canned and are stored in Yŏngbyŏn awaiting shipment to still undetermined third country. The agreement has also frozen this reactor, which is scheduled for dismantlement after the Korean Peninsula Energy Development Organization (KEDO) has completed the project to provide two light-water nuclear reactors at Shinp’o, South Hamgyŏng Province.

The amount of plutonium that could have been extracted from 5MW(e) Experimental Reactor depends upon the reactors operational history, North Koreas reprocessing technology, and whether North Korea fully exploited the opportunities provided by the reactor shutdowns in 1989, 1990 and 1991. According to data collected by IAEA inspectors, particularly samples of Americium-241 and the distribution of the Plutonium isotopes in the sample provided with Pyongyangs initial declaration, North Korea almost certainly reprocessed Plutonium in all three years. However, the periods of shutdown in 1990 and 1991 were probably not sufficient to replace the entire reactor core, thus reducing the amount of Plutonium that could have been reprocessed. Most analysts agree with David Albrights assessment that an upper bound for the amount of Plutonium that could have been reprocessed from this reactors spent fuel is about 6.9-10.7kg. Given the approximate 4.0kg that could have been reprocessed from the IRT-2000 Nuclear Research Reactor, North Korea could have enough weapon-grade Plutonium for two bombs.

General Data

Owner: Probably the Nuclear Physics Research Institute (Institute of Nuclear Physics in Yŏngbyŏn)
Operator: Probably the Yŏngbyŏn Nuclear Research Center (Center for Atomic Energy)
Licensing:
Construction Date: 1979-1980
Criticality Date: 14 August 1985
Operation Date: January 1986
Safeguards: Frozen under the Agreed Framework; monitored by the IAEA, but completion of full scope safeguards still pending
Status: Frozen

Technical Data and Experimental Facilities

Reactor Type: Graphite-moderated, gas-cooled, Magnox, (UK Calder Hall)
Power (Thermal): 20-25MW
Moderator: Graphite
Coolant: CO2
Reflector Number of Sides:
Number of Horizontal Channels:
Number of Vertical Channels: 812

Fuel Data

Origin of Fissile Material: North Korea
Cladding Material: Magnox (Magnesium-0.5% Zirconium)

Technical references: David Albright and Kevin O’Neill, eds., Solving the North Korean Nuclear Puzzle, (Washington, D.C.: Institute For Science and International Security, 2000); Kim Byŏng Ku et al., Pukhaekkisulch’ongsŏ-I (North Korean Nuclear Issues and the LWR Project), KAERI/AR-552-99, Technology Center for Nuclear Control, November 1999, <http://www.tcnc.kaeri.re.kr>.