Norwegian heavy water sabotage Totally Explained

Everything about Operation Gunnerside totally explained

The Norwegian heavy water sabotage was a series of actions taken by Norwegian saboteurs during World War II to prevent the German nuclear energy project from acquiring heavy water which could be used to produce nuclear weapons.
Between 1942 and 1944 a sequence of sabotage actions by the Norwegian resistance movement, as well as Allied bombing, ensured the destruction of the plant and the loss of the heavy water produced. These operations — codenamed "Freshman", "Grouse" and "Gunnerside" — finally managed to knock the plant out of production in early 1943, basically ending the German research.
The raid was later dubbed by the British SOE as the most successful act of sabotage in all of World War II.

Technical background

When Nazi Germany investigated the possibility of building an atomic bomb, a range of potential paths forward became clear. Details of how the decision to go down the heavy water route was made are likely to remain somewhat obscure but, although unsuccessful, it was based on what was later demonstrated to be a technically viable approach:

Plutonium-239 (²³⁹Pu) makes an effective weapons material.
Heavy water has been demonstrated as an effective moderator for ²³⁹Pu production.
Heavy water may be separated from regular water by electrolysis.

Approaches to developing a weapon

In nuclear weapon development, the main problem is securing sufficient "weapons grade" material, in particular the fissile isotopes of either uranium-235 (²³⁵U) or ²³⁹Pu. In order to produce weapons grade uranium, one may elect to extract uranium from natural ore and enrich it. Alternately one can "breed" plutonium in a nuclear reactor using unenriched uranium as a fuel and then chemically separate the ²³⁹Pu produced. Unlike the Allies, who chose to pursue both the enrichment of uranium and production of plutonium in reactors, German scientists elected to focus on plutonium production, as the industrial complex required to make weapons this way was less expensive.

Plutonium production

Although the most common isotope of uranium, uranium-238 (²³⁸U), can't be used as the primary fissile material for an atomic bomb (it can be used as secondary fissile material in hydrogen bombs), ²³⁸U can be used to produce ²³⁹Pu. The fission of ²³⁵U produces neutrons, some of which will be absorbed by ²³⁸U creating ²³⁹U. After a few days the ²³⁹U will decay, turning into weapons-usable ²³⁹Pu. The Germans didn't examine ultrapure graphite because they didn't know that the graphite they'd tried was too impure to sustain a chain reaction, and abandoned it as a possible moderator. They instead settled on the heavy-water-based reactor design. A heavy water moderated nuclear reactor could be used to do nuclear fission research, and, ultimately, to breed plutonium from which a bomb could be constructed.

Heavy water production

Heavy-water is a byproduct of ammonia fertilizer production. Hydrogen was, at the time, mainly produced by electrolysis of water. The Haber Process is then used, reacting the hydrogen with nitrogen from air to produce ammonia. At the time, Europe's major supply of ammonia came from the Norwegian Vemork hydroelectric plant, run by Norsk Hydro, near Rjukan in the Telemark region.
The technology is very simple and straightforward. Heavy water (D₂O) is separated from regular water by electrolysis because the difference in mass between the two hydrogen isotopes translates into a slight difference in the speed at which the reaction proceeds. To produce pure heavy water by electrolysis requires a large cascade of electrolysis chambers, and consumes large amounts of power. Since the production of hydrogen relied on electrolysis at Vemork, heavy water was a routine byproduct. Hans Suess was a German advisor to the production of heavy water. Suess had assessed the Rjukan plant as being incapable of producing militarily useful quantities of heavy water in less than five years at its then current capacity.

Operations Freshman and Grouse

Destruction of the plant was mounted by the Combined Operations command in November 1942. The plan consisted of two operations: the first would drop a number of Norwegian locals into the area as an advance force, and once in place a party of British engineers would be landed by glider to attack the plant itself.
   On 19 October 1942, a four man team of Special Operations Executive (SOE) trained Norwegian commandos parachuted into Norway. From their drop point in the wilderness they'd to ski a long distance to the plant, so considerable time was given to complete this part of the mission, known as Operation Grouse. This plan, unlike those which didn't succeed before, included the team studying and memorising blueprints.
   Once the Norwegian Grouse team managed to make contact with the British, the British were suspicious, as they hadn't heard from the SOE team for a long time: they'd been dropped at the wrong place, and had gone off course from there several times. The secret question took the form of: "What did you see in the early morning of (a day)?" The Grouse team replied: "Three pink elephants." The British were ecstatic at the success of Norwegian team's insertion, and the next phase of operations commenced.
   On 19 November 1942, Operation Freshman followed with the planned gliderborne landing on frozen lake Møsvatn near the plant. The two Airspeed Horsa gliders, towed by Handley Page Halifax bombers, each glider carrying two pilots and fifteen Royal Engineers of the 9th Field Company, 1st British Airborne Division, took off from RAF Skitten near Wick in Caithness. The towing of gliders had always been a hazardous profession, but in this case made worse by the long flying distance to Norway and poor weather conditions which heavily restricted visibility. One of the Halifax tugs crashed into a mountain, killing all seven aboard; its glider was able to cast off, and crashed nearby, resulting in several casualties. The other Halifax successfully arrived at the area of the landing zone, but although the conditions had substantially improved it was impossible to locate the landing zone itself due to the failure of the link between the Eureka (ground) and Rebecca (aircraft) beacons. After much endeavour and with fuel running low, the Halifax pilot decided to abort the operation and return to base. However, shortly afterwards, the tug and glider combination encountered heavy cloud and in the resulting turbulence the tow rope broke. The glider made a crash landing, not far from where the other glider had come down, similarly inflicting several deaths and injuries. The Norwegians were unable to reach the crash sites in time, and the survivors eventually came into the hands of the Gestapo, who tortured them during interrogation (not sparing the badly injured) and later had them executed under Hitler's Commando Order. The most important consequence of the unsuccessful raid, was that the Germans were now alerted to a determined Allied interest in their heavy water production.
   The Norwegian Grouse team thereafter had a long arduous wait in their mountain hideaway, subsisting on moss and lichen during the winter until, just before Christmas, a reindeer was encountered.
   A 1948 Norwegian movie based on this raid, called Kampen om tungtvannet, features performances by at least four of the original participants in the raid. (External Link

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Operation Gunnerside

British authorities were aware of the "success" of the Grouse team, and decided to mount another operation in concert with them. By this time the original Grouse team were being referred to as Swallow. On the night of 16th February 1943, in Operation Gunnerside (named after a village and the moor where the Hambro Family and Sir Charles Hambro, the head of SOE, used to shoot grouse), an additional six Norwegian commandos were dropped by parachute by a Halifax bomber of 138 Squadron from RAF Tempsford. They were successful in landing, and encountered the Swallow team after a few days of searching. The combined team made final preparations for their assault, which was to take place on the night of 27 February.
   Supplies required by the commandos were dropped with them in special CLE containers. (One of these was buried in the snow by a Norwegian patriot to hide it from the Germans; he later recovered it and in August 1976 handed it over to an officer of the (British) Army Air Corps, who were exercising in the area. The container was brought back to England and is now on display at the Airborne Museum at Aldershot.)
   Following the failed Freshman attempt, mines, floodlights and additional guards were set around the plant. Whilst the mines and lights remained in place, security of the actual plant had slackened somewhat over the winter months. However, the single 75-metre bridge spanning the deep ravine, 200 metres above the River Maan, was fully guarded.
   The force elected to descend into the ravine, ford the icy river and climb the steep hill on the far side. The winter river level was very low, and on the far side, where the ground leveled, they followed a single railway track straight into the plant area without encountering any guards. Even before Grouse landed in Norway, SOE had a Norwegian agent within the plant who supplied detailed plans and schedule information. The demolition party used this information to enter the main basement by a cable tunnel and through a window. Inside the plant the only person they came across was the Norwegian caretaker (Johansen), who was very willing to cooperate with them.
   The saboteurs then placed explosive charges on the heavy water electrolysis chambers, and attached a fuse allowing sufficient time for their escape. A British submachine gun was purposely left behind to indicate that this was the work of British forces and not of the local resistance, in order to alleviate reprisals. A surreal episode ensued when fuses were about to be lit: The caretaker was worried about his spectacles which were lying somewhere in the room (during the war new glasses were nearly impossible to acquire). A frantic search for the caretaker's spectacles ensued, they were found - and the fuses lit! The explosive charges detonated, destroying the electrolysis chambers.
   All ten commandos made good their escape whereafter six of them skied 400 kilometres to Sweden and four remained in Norway for further work with the resistance. The Vemork plant was restored by April and SOE concluded that a repeat raid would be extremely difficult, as German security now was very considerable. In November the plant was attacked by a massed daylight bombing raid of 143 B-17 bombers dropping 711 bombs, of which at least 600 missed the plant. The damage, however, was quite extensive; the reason for the original ground assault a year earlier was that the available alternative of night bombing was considered unrealistic at that time.

Aftermath

While this attack did little damage to the plant, it did stop production for a short period. Almost as soon as production re-started, the USAAF started a series of raids on Vemork. The Germans were convinced that this would eventually result in some "hits," and they decided to abandon the plant and move remaining stocks and critical components to Germany in 1944. Knut Haukelid was made aware of their plan and decided to sabotage the ferry carrying the heavy water across Lake Tinnsjø. He recognised a ferry crew member and talked to him, taking this advantage to slip into the bottom of the ship and plant the bomb, after which he slipped away. Eight and half kilograms of plastic explosive with two alarm-clock fuses were fixed to the keel of the ferry, D/F Hydro, which was to carry the railway cars with the heavy water drums across Lake Tinnsjø. On 20 February 1944, shortly after setting off around midnight, the ferry and its cargo sank in deep water, finally capping the original mission's objective and halting Germany's atomic bomb development programme. A number of Norwegian civilians were killed as the ferry sank. Witnesses reported seeing steel drums floating after the sinking, leading to speculation that they didn't really contain heavy water. But an examination of records after the war showed that some barrels were only half full, and therefore would have floated. A few of these may have been salvaged and transported to Germany. Around 2005, an expedition retrieved a barrel (numbered "26") from the bottom of the lake. Its contents of heavy water matched the concentration noted in the German records, and confirmed that the shipment wasn't a decoy. However, it also supported the notion that the concentration of heavy water in a number of the barrels was too small to be of value to a weapons program. This might explain the absence of heavy security measures around the shipment, including why the ferry itself wasn't searched for delayed charges.
Unknown to the saboteurs, a "Plan B" had been set up by the SOE, who arranged a second team to attack the shipment at Herøya should the first attempt fail. The disassembled factory was later found in southern Germany during the closing stages of the war by members of the Operation Alsos nuclear seizure force.
With the benefit of hindsight, the consensus on the German wartime nuclear program is that it was a long way from producing a bomb, even with the Norwegian heavy water. Nevertheless, the unsuccessful British raid (FRESHMAN) and the feats of the Norwegian saboteurs (SWALLOW, GROUSE, GUNNERSIDE) made the top secret war against the heavy water production internationally known and the saboteurs national heroes.

SOE Norwegian agents involved

The first agent inside the plant � :Einar Skinnarland

The Grouse/Swallow Team � :Jens Anton Poulsson

:Arne Kjelstrup � :Knut Haugland

:Claus Helberg

The Gunnerside Team � :Joachim Rønneberg (Joachim Holmboe Rønneberg)

   :Knut Haukelid � :Fredrik Kayser

   :Kasper Idland � :Hans Storhaug

   :Birger Strømsheim � :(Leif Tronstad) (planner, in the United Kingdom)

The Lake Tinnsjø Team � :Knut Haukelid, alias "Bonzo"

   :Rolf Sørlie (local resistance) � :Einar Skinnarland (base wireless operator)

   :Gunnar Syverstad (plant lab assistant) � :Kjell Nielsen (plant transport manager)

   :(“Larsen”) (senior plant engineer) � :(NN) (car procurer and driver)

Books, films, radio and television programs

A Norwegian black and white semi-documentary film, produced in 1948, titled Kampen om tungtvannet (trans. "The Fight for Heavy Water"), featured some of the original saboteurs playing themselves.

Some of these exploits were used as the basis for the US 1965 war movie The Heroes of Telemark starring Kirk Douglas whose character, Dr. Rolf Pedersen, was supposed to be GROUSE member Joachim Rønneberg. Rønneberg stated himself, "The Fight for Heavy Water was an honest attempt to describe history. The Heroes of Telemark, on the other hand, had little to do with reality."

The book The Real Heroes of Telemark: The True Story of the Secret Mission to Stop Hitler's Atomic Bomb by Ray Mears, published by Hodder & Stoughton 2003 (ISBN 0-340-83016-6) describes the events from the perspective of the unique survival skills of the Norwegian commandos. It accompanied a BBC television documentary series, The Real Heroes of Telemark, which sticks more to the facts than the Hollywood film it's named after. It also describes the survival aspects of the attack - how to survive for months in a mountain cabin. The name is an obvious pun on the Hollywood effort and its inaccuracies.

The book Skis Against the Atom (ISBN 0-942323-07-6) is a the first-hand account by Knut Haukelid, one of the raiders who stayed behind.

The book Assault In Norway: Sabotaging the Nazi Nuclear Program by Thomas Gallagher, published by Harcourt Brace Jovanovich, 1975 (ISBN 0-15-109582-5) / The Lyons Press, 2002 (ISBN 1-58574-750-5) focuses on the part played by the Norwegian commandos.

The book Operation Freshman: The Rjukan Heavy Water Raid, 1942 by Richard Wiggan, published by W. Kimber, 1986 (ISBN 0-7183-0571-X) focuses on the ill-fated Operation FRESHMAN.

The book Blood and Water: Sabotaging Hitler's Bomb by Dan Kurzman, published by Henry Holt & Company, 1997 (ISBN 0-8050-3206-1) documents all operations against the Vemork plant.

The book E=MC2: A Biography of the World's Most Famous Equation (ISBN 0-330-39165-8) has a rather detailed section on the raid.

The book Between Silk and Cyanide by Leo Marks has a chapter about the raid, from the viewpoint of an SOE cryptographer who helped organize the communications between the SOE and the saboteurs.

The 2003 BBC Radio 4 program Telemark Heroes

, Julian Pettifer talked to survivors of Operation Gunnerside, Listen Again

The 2004 Australian Broadcasting Corporation's The Big Picture: Real Heroes Of Telemark

, written and produced by Martin Pailthorpe, executive produced by Dick Colthurst.

The 2005 PBS documentary Hitler's Sunken Secret (about retrieving barrel no 26 - see above).

The book The Making of the Atomic Bomb by Richard Rhodes (ISBN 0-684-81378-5) has a detailed section on the raid.

In addition, there's a number of books in Norwegian covering the dramatic fight for Heavy Water.

The book Commando Country by Stuart Allan, National Museums Scotland 2007, ISBN 9781905267149 has a section on the training and preparation for the raids in Scotland.

Ray Mears made a TV program called The Real Heroes of Telemark, retracing their steps, and how they survived.

There is a new film planned by the Norwegian Production company "Filmkameratene". It's a remake of the 1948 film "Kampen om tungtvannet".http://www1.vg.no/film/artikkel.php?artid=142643

The game Commandos Strike Force features a level loosely based on the sabotage.

References and notes

Further Information

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