Never-used Cold War era nuclear bunker opens to the public

To get to the bunker complex itself, one must first go through a 300-meter-long tunnel that curves through the hill. Illustration: Lars Horn/Nordjyske Museer

The chief engineer just received the message on the radio.

The Danish government, the royal family, and representatives of the press are currently being transported from Copenhagen to a small, unsightly nook in the Rold Skov forest.

For the past few years, the chief engineer has been guarding the tremendous secret hidden behind his yellow detached house—on a small country road between the towns of Rebild and Årestrup in North Jutland.

If you follow the dirt road past the chief engineer’s residence round a few bends and a short distance up a hill, you come to a large metal gate, which—together with two uniformed guards—demarcates Denmark’s best-kept secret at the time:

A 5,000-square-meter underground bunker complex under the code name “REGAN Vest” (which stands for “Government Facility West Denmark” in Danish), built to maintain and govern Denmark through a time of national crisis.

As the bunker’s technical manager, it is the chief engineer’s task to ensure that the facility is ready for use and, if necessary, that the bunker is not contaminated by radioactive fallout while Denmark’s ministers lead the country from the bunker’s small offices.

Oxygen, water, and food supplies

REGAN Vest was built in the 1960s but fortunately never came into use. In 2014, the secret was revealed and the facility was protected. It now opens to the public as an exhibition with an associated newly-designed museum building.

On this occasion, Ingeniøren has visited the heart of the facility and taken a journey back in time to find out how a bunker is kept operational and secured while the country is on the brink of collapse.

Everything in the bunker is redundant, including the two generators that can each power the bunker on their own. Illustration: Lars Horn/Nordjyske Museer

The first thing the chief engineers needs to do is make sure there is power in the bunker. To do that, he has to go through a 300-meter-long, white corridor. At a certain point, the corridor splits into two corridors, one of which is a dead end. It is a blast tunnel that is supposed to take the first big hit from a bomb if the enemy finds the bunker.

At the end of the second tunnel, the chief engineer reaches the engine room. Inside are two large, blue diesel generators made by the company Titan Auto Diesel. With a power of 330 kVA, they can each supply the bunker with electricity on their own, and they can replace each other should something go wrong with one of them. Below the engine room are six tanks, each containing 12,000 litters of diesel, ready to supply the engines.

Next, the engineer must provide clean water for the bunker’s future residents. Here, too, redundancy is the key word, because three groundwater boreholes are ready to supply two waterworks with water directly from the groundwater source under the Rold Skov forest.

The bunker is equipped to adapt to the situation outside. If there are no immediate threats on the other side, a ventilation system can replace the air in the bunker.

But if the enemy becomes aware of the location of the bunker, and if, for example, poison gas is spread in the area, large barrels of finely granulated calcium lime are ready to be poured into one of the two air filters.

If the bomb drops

The basic prerequisites for up to 350 people to survive underground are in now place. If the situation that has activated REGAN Vest is not so serious that it makes it impossible to supply food, medicine, fuel, etc., the bunker can in principle be kept running as long as it needs to be.

But if the Warsaw Pact goes through with its threats of nuclear weapons, and mushroom clouds begin to rise over Jutland, the countdown begins:

about a week. That is how long the bunker can keep running in lockdown mode. This time pressure is most evident in the room that contains 50 oxygen tanks. If the bunker is locked down, the last reserves of oxygen are found here, and as the tanks are emptied, red labels are placed on the empty ones. So, as a technician, you get the front row seat to the final countdown, if it comes to that.

Communication with the outside world was a sensitive subject in the once top-secret bunker. Among other things, the Danish Ministry of Defence has installed cipher devices so that messages cannot be read if they are intercepted by the enemy. Illustration: Lars Horn/Nordjyske Museer

But the risk of this scenario is fortunately not that great, because the bunker was built with the nuclear threat in mind. Therefore, it is built in a way that enables a certain exchange of oxygen, even if the area is hit by radioactive fallout.

First, the air is sucked into a large cavity, which also protects the bunker itself against vibrations. Here, the air circulates so that the dust can settle. The air is then sent through a bed of stones to reduce the shockwave, after which it is finally purified in the facility’s 12 radiation filters.

The technical staff have the risky task of changing these filters, which requires a thick lead apron and subsequent rest to recover from potential radiation sickness.

From switchboard operators to fibre-optic network

It is, of course, not just one all-knowing technician who is responsible for all the technical functions of the bunker. The team consists of a number of technicians and assistants, each of whom has a role to fill.

The key idea behind REGAN Vest is that democracy must be maintained even in a crisis situation that is so extensive that it is not safe to lead the country from Zealand. Large meeting rooms, furnished with maps of Europe, are reserved for the top government officials, while a microphone transmits the meeting to the neighbouring rooms, where the ministry staff sits ready to rush down to his/her majesty, in the event that a bill needs to be signed urgently.

But orders also need to be issued from REGAN Vest, and while the bunker was in a state of preparedness, different communication technologies cycled through it. In the early years, switchboard operators from the Danish Women’s Defence Organisation were sitting at the switchboard, ready to direct the internal communication in the bunker.

If the bunker can no longer take in fresh air, for example due to a gas attack, 50 oxygen tanks are the last option left. Illustration: Lars Horn/Nordjyske Museer

However, telephone area codes presented a problem, because the location had to be kept secret. Therefore, the bunker is equipped with six area codes, so that the location cannot be traced through them.

In addition, the communications room also contained telegraphs, cipher devices, and in the latest time even fibre-optic cables.

However, none of that came into use—but REGAN Vest provides an opportunity to get an insight into some of what went on behind the scenes of the Cold War.

The Cold War Museum REGAN Vest opens to the public on Monday 13 February. The bunker can only be accessed with a guided tour, which must be booked in advance. Read more at