In a March 27, 2018, New York Times (NYT) article entitled, “North Korea Is Firing Up a Reactor. Why That Could Upset Trump’s Talks With Kim.,” the authors conclude that North Korea’s Experimental Light Water Reactor (ELWR) is now in the process of starting up. Although the article draws heavily from an earlier article by Jane’s Intelligence Review which is generally consistent with our own reporting, the NYT article went too far in suggesting that the reactor is beginning operations. In the absence of other corroborating data, that conclusion is premature at best and is likely wrong.
Ventilation vs. Operation
Commercial satellite imagery from February 25, 2018 shows what could be a small wisp of some type of vapor emanating from the elevated ventilation stack that serves the ELWR. There are serious doubts as to whether this is actually vapor; it may simply be a ground feature of a lighter color associated with the driveway. But even if it is vapor, a ventilation stack is not intended for the removal of any operations exhaust, steam or smoke. Rather, it is designed to provide a mechanism to allow small releases of filtered, radioactive gases that accumulate in the reactor halls and for pressure relief to prevent containment failure due to internal gas pressure in the event of an accident.
The Jane’s authors originally suggested this apparent emission—if it is an emission—could be evidence of “pre-operations testing.” However, such a visible emission could just be evidence that the North Koreans were testing part of the ventilation or emergency overpressure gaseous relief system, which is a reasonable course of action but does not necessarily mean that the next step will be to start operations. In doing so, the North Koreans could have exposed the pressure relief valve to a source of high pressure inert gas leading to the apparent wisp emission.
Moreover, the NYT mislabeling of this ventilation stack as a “smokestack” creates further unnecessary confusion over the operational status of the ELWR. In reality, any emission from the ventilation stack serving the reactor is only indicative of testing of the emergency ventilation systems and not a signature of “firing up the reactor” as the title suggests. In fact, any “smoke” from a ventilation stack that serves a nuclear reactor would only suggest that the reactor is on fire.
Is the ELWR Close to Becoming Operational?
If commercial satellite imagery from February 25 does actually show a wispy emission of some kind from the reactor ventilation stack—and again there are serious doubts that it does—it is most likely part of a checkout procedure for the ventilation system. However, no emission from the stack can be construed as indicative of startup operations as that is not the purpose of a ventilation stack. Rather, such an emission should only be interpreted as evidence of ongoing checkout preparations, moving the ELWR closer to operations at some as yet indeterminable time in the future.
38 North analysts will continue to monitor the ELWR for any evidence of initial operations which may include hot water discharge from the ELWR into the Kuryong river and thermal indicators of operations at the reactor facility.
Figure 1. Close-up of the ELWR at Yongbyon Scientific Nuclear Research Center on February 25, 2018.
The purpose of a ventilation stack is to remove all non-condensable gases from the reactor containment building, which during normal operations come from noble gas fission products that diffuse from the fuel elements in the reactor’s core, to the operating hall above the containment vessel and the core (particularly Kr-85 and Xe-131). During emergency operation there could be many sources of gases in the reactor hall. Most gasses are removed by the reactor hall’s water and chemical sprays, which are located near the top of the containment structure. The remaining non-condensable gases are then discharged through the ventilation stack. The taller the stack the better the dispersion of the emitted gases away from the reactor site and nearby population centers.
Some of the figures generated by Jane’s and republished in the NYT erroneously labeled the condensed water vapor rising from the cooling tower previously associated with the 5MWe plutonium production reactor as “smoke.”