Norwegian heavy water sabotage

Norwegian heavy water sabotage

Overview
The Norwegian heavy water sabotage was a series of actions undertaken by Norwegian saboteurs during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 to prevent the German nuclear energy project
German nuclear energy project
The German nuclear energy project, , was an attempted clandestine scientific effort led by Germany to develop and produce the atomic weapons during the events involving the World War II...

 from acquiring heavy water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...

 (deuterium oxide), which could be used to produce nuclear weapon
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

s. In 1934, at Vemork
Vemork
Vemork is the name of a hydroelectric power plant outside Rjukan in Tinn, Norway. The plant was built by Norsk Hydro and opened in 1911, its main purpose being to fix nitrogen for the production of fertilizer. Vemork was later the site of the first plant in the world to mass-produce heavy water...

, Norsk Hydro
Norsk Hydro
Norsk Hydro ASA is a Norwegian aluminium and renewable energy company, headquartered in Oslo. Hydro is the fourth largest integrated aluminium company worldwide. It has operations in some 40 countries around the world and is active on all continents. The Norwegian state holds a 43.8 percent...

 built the first commercial plant capable of producing heavy water as a byproduct of fertilizer production. It had a capacity of 12 t (13.2 ST) per year. During World War II, the Allies
Allies of World War II
The Allies of World War II were the countries that opposed the Axis powers during the Second World War . Former Axis states contributing to the Allied victory are not considered Allied states...

 decided to remove the heavy water supply and destroy the heavy water plant in order to inhibit the Nazi
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 development of nuclear weapons.
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Encyclopedia
The Norwegian heavy water sabotage was a series of actions undertaken by Norwegian saboteurs during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 to prevent the German nuclear energy project
German nuclear energy project
The German nuclear energy project, , was an attempted clandestine scientific effort led by Germany to develop and produce the atomic weapons during the events involving the World War II...

 from acquiring heavy water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...

 (deuterium oxide), which could be used to produce nuclear weapon
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

s. In 1934, at Vemork
Vemork
Vemork is the name of a hydroelectric power plant outside Rjukan in Tinn, Norway. The plant was built by Norsk Hydro and opened in 1911, its main purpose being to fix nitrogen for the production of fertilizer. Vemork was later the site of the first plant in the world to mass-produce heavy water...

, Norsk Hydro
Norsk Hydro
Norsk Hydro ASA is a Norwegian aluminium and renewable energy company, headquartered in Oslo. Hydro is the fourth largest integrated aluminium company worldwide. It has operations in some 40 countries around the world and is active on all continents. The Norwegian state holds a 43.8 percent...

 built the first commercial plant capable of producing heavy water as a byproduct of fertilizer production. It had a capacity of 12 t (13.2 ST) per year. During World War II, the Allies
Allies of World War II
The Allies of World War II were the countries that opposed the Axis powers during the Second World War . Former Axis states contributing to the Allied victory are not considered Allied states...

 decided to remove the heavy water supply and destroy the heavy water plant in order to inhibit the Nazi
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 development of nuclear weapons. Raids were aimed at the 60-MW Vemork power station at the Rjukan
Rjukan
Rjukan is a town and the administrative center of Tinn municipality in Telemark . It is situated in Vestfjorddalen, between Møsvatn and Tinnsjå, and got its name after Rjukanfossen west of the town. The Tinn municipality council granted township status for Rjukan in 1996. The town has 3 386...

 waterfall in Telemark
Telemark
is a county in Norway, bordering Vestfold, Buskerud, Hordaland, Rogaland and Aust-Agder. The county administration is in Skien. Until 1919 the county was known as Bratsberg amt.-Location:...

, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

.

Prior to the German invasion of Norway on 9 April 1940, the Deuxième Bureau
Deuxième Bureau
The Deuxième Bureau de l'État-major général was France's external military intelligence agency from 1871 to 1940. It was dissolved together with the Third Republic upon the armistice with Germany...

(French military intelligence) removed 185 kg (408 lb) of heavy water from the plant in Vemork in then-neutral Norway. The plant′s managing director, Aubert, agreed to loan the heavy water to France for the duration of the war. The French transported it secretly to Oslo
Oslo
Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King...

, to Perth
Perth, Scotland
Perth is a town and former city and royal burgh in central Scotland. Located on the banks of the River Tay, it is the administrative centre of Perth and Kinross council area and the historic county town of Perthshire...

, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

, and then to France. The plant remained capable of producing heavy water.

The Allies remained concerned that the occupation forces would use the facility to produce more heavy water for their weapons programme. Between 1940 and 1944, a sequence of sabotage
Sabotage
Sabotage is a deliberate action aimed at weakening another entity through subversion, obstruction, disruption, or destruction. In a workplace setting, sabotage is the conscious withdrawal of efficiency generally directed at causing some change in workplace conditions. One who engages in sabotage is...

 actions, by the Norwegian resistance movement
Norwegian resistance movement
The Norwegian resistance to the occupation of Norway by Nazi Germany began after Operation Weserübung in 1940 and ended in 1945. It took several forms:...

—as well as Allied bombing
Strategic bomber
A strategic bomber is a heavy bomber aircraft designed to drop large amounts of ordnance onto a distant target for the purposes of debilitating an enemy's capacity to wage war. Unlike tactical bombers, which are used in the battle zone to attack troops and military equipment, strategic bombers are...

—ensured the destruction of the plant and the loss of the heavy water produced. These operations—codenamed "Grouse," "Freshman," and "Gunnerside"—finally managed to knock the plant out of production in early 1943.

In Operation Grouse, the British Special Operations Executive
Special Operations Executive
The Special Operations Executive was a World War II organisation of the United Kingdom. It was officially formed by Prime Minister Winston Churchill and Minister of Economic Warfare Hugh Dalton on 22 July 1940, to conduct guerrilla warfare against the Axis powers and to instruct and aid local...

 (SOE) successfully placed four Norwegian nationals as an advance team in the region of the Hardanger Plateau above the plant. Later in 1942 the unsuccessful Operation Freshman was mounted by British paratroopers; they were to rendezvous with the Norwegians of Operation Grouse and proceed to Vemork. This attempt failed when the military glider
Military glider
Military gliders have been used by the military of various countries for carrying troops and heavy equipment to a combat zone, mainly during the Second World War. These engineless aircraft were towed into the air and most of the way to their target by military transport planes, e.g...

s crashed short of their destination, as did one of the tugs, a Halifax bomber. The other Halifax returned to base, but all the other participants were killed in the crashes or captured, interrogated, and executed by the Gestapo
Gestapo
The Gestapo was the official secret police of Nazi Germany. Beginning on 20 April 1934, it was under the administration of the SS leader Heinrich Himmler in his position as Chief of German Police...

.

In 1943, a team of SOE-trained Norwegian commandos succeeded in destroying the production facility with a second attempt, Operation Gunnerside. Operation Gunnerside was later evaluated by SOE as the most successful act of sabotage in all of World War II.

These actions were followed by Allied bombing raids. The Germans elected to cease operation and remove the remaining heavy water to Germany. Norwegian resistance forces sank the ferry, SF Hydro
SF Hydro
SF Hydro was a Norwegian steam powered railway ferry that operated on Tinnsjø in Telemark. The ferry operated between Mæl and Tinnoset between 1914 and 1944, connecting the two railways Rjukanbanen and Tinnosbanen. The railway was used to transport raw materials and fertilizer from Norsk Hydro's...

, on Lake Tinnsjø, preventing the heavy water from being removed.

Technical background


Enrico Fermi
Enrico Fermi
Enrico Fermi was an Italian-born, naturalized American physicist particularly known for his work on the development of the first nuclear reactor, Chicago Pile-1, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics...

 and his colleagues studied the results of bombarding uranium with neutrons in 1934. The first person who mentioned the idea of nuclear fission
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...

 in 1934 was Ida Noddack
Ida Noddack
Ida Noddack , née Ida Tacke, was a German chemist and physicist. She was the first to mention the idea of nuclear fission in 1934. With her husband Walter Noddack she discovered element 75 rhenium...

. After the Fermi publication, late in 1938, Lise Meitner
Lise Meitner
Lise Meitner FRS was an Austrian-born, later Swedish, physicist who worked on radioactivity and nuclear physics. Meitner was part of the team that discovered nuclear fission, an achievement for which her colleague Otto Hahn was awarded the Nobel Prize...

, Otto Hahn
Otto Hahn
Otto Hahn FRS was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry". Hahn was a courageous opposer of Jewish persecution by the Nazis and after World War II he became a passionate campaigner...

 and Fritz Strassman confirmed nuclear fission. Physicists everywhere realized that if chain reactions could be tamed, fission could lead to a promising new source of power. What was needed was a substance that could "moderate" the energy of neutrons emitted in radioactive decay, so that they could be captured by other fissile nuclei. Heavy water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...

 and graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...

 were the prime candidates for moderating the energy of neutrons.

When Nazi Germany
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 investigated the possibility of building an atomic bomb, a range of options were identified. Although historical records provide limited detail on the German decision to pursue the heavy water approach, it became clear after the war that they had explored the option. Although ultimately unsuccessful, the approach chosen has been demonstrated to be technically viable:
  • Plutonium
    Plutonium
    Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...

    -239 (239Pu) makes an effective weapons material.
  • Heavy water has been demonstrated as an effective moderator
    Neutron moderator
    In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235....

     for 239Pu production.
  • Heavy water
    Heavy water
    Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...

     may be separated from regular water by electrolysis
    Electrolysis
    In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...

    .

Approaches to developing a weapon


In nuclear weapon development, the main problem is securing sufficient "weapons grade" material, in particular the fissile isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

s of either uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...

-235 (235U) or 239Pu. In order to produce weapons grade uranium, one may elect to extract uranium from natural ore and enrich
Enriched uranium
Enriched uranium is a kind of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% 238U isotope, with 235U only constituting about 0.711% of its weight...

 it. Alternately one can "breed" plutonium in a nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

 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
Uranium-238
Uranium-238 is the most common isotope of uranium found in nature. It is not fissile, but is a fertile material: it can capture a slow neutron and after two beta decays become fissile plutonium-239...

 (238U), cannot 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 did not examine ultra pure graphite because they did not know that the graphite they had tried was too impure to sustain a chain reaction, and abandoned it as a possible moderator. They instead settled on the heavy-water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...

-based reactor design. A heavy water moderated nuclear reactor could be used to do nuclear fission research, and, ultimately, to breed plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...

 from which a bomb could be constructed.

Heavy water production



Heavy water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...

 occurs in very low concentrations (1 part in 6,000) in normal water but is more concentrated in the residue of water used as an electrolyte. An analysis of the residues from the Norwegian
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 Vemork
Vemork
Vemork is the name of a hydroelectric power plant outside Rjukan in Tinn, Norway. The plant was built by Norsk Hydro and opened in 1911, its main purpose being to fix nitrogen for the production of fertilizer. Vemork was later the site of the first plant in the world to mass-produce heavy water...

 hydroelectric plant, run by Norsk Hydro
Norsk Hydro
Norsk Hydro ASA is a Norwegian aluminium and renewable energy company, headquartered in Oslo. Hydro is the fourth largest integrated aluminium company worldwide. It has operations in some 40 countries around the world and is active on all continents. The Norwegian state holds a 43.8 percent...

, near Rjukan
Rjukan
Rjukan is a town and the administrative center of Tinn municipality in Telemark . It is situated in Vestfjorddalen, between Møsvatn and Tinnsjå, and got its name after Rjukanfossen west of the town. The Tinn municipality council granted township status for Rjukan in 1996. The town has 3 386...

 in the Telemark
Telemark
is a county in Norway, bordering Vestfold, Buskerud, Hordaland, Rogaland and Aust-Agder. The county administration is in Skien. Until 1919 the county was known as Bratsberg amt.-Location:...

 region, a large-scale hydrogen production plant using electrolysis
Electrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...

 of water for ammonia production, showed a concentration of 1 part in 2,300. Leif Tronstad
Leif Tronstad
Leif Hans Larsen Tronstad DSO, OBE was a Norwegian scientist, intelligence officer and military organizer. He graduated from the Norwegian Institute of Technology in 1927 and was a prolific researcher and writer of academic publications...

, then a lecturer at the Norwegian Institute of Technology
Norwegian Institute of Technology
The Norwegian Institute of Technology, known by its Norwegian abbrevation NTH was a science institute in Trondheim, Norway. It was established in 1910, and existed as an independent technical university for 85 years, after which it was merged into the University of Trondheim as an independent...

 and Jomar Brun, head of the hydrogen plant put forward a proposal in 1933, the year heavy water was first isolated, for a project, which was accepted by Norsk Hydro and production started in 1935.

The technology is 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 there was excess power available, heavy water could be purified from the existing electrolyte. As a result, Norsk Hydro became the heavy water supplier for the world′s scientific community, as a byproduct of fertilizer production, for which the ammonia was used.

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.

Pre-invasion efforts


French research considered production of 239Pu using both heavy water and graphite moderated reactors. Preliminary French research indicated that the graphite which was then available commercially was not pure enough to serve the purpose, and that heavy water would be required. The German research community had reached a similar conclusion and in January 1940 had procured additional heavy water from Vemork. The German firm IG Farbenindustrie Aktiengesellschaft
IG Farben
I.G. Farbenindustrie AG was a German chemical industry conglomerate. Its name is taken from Interessen-Gemeinschaft Farbenindustrie AG . The company was formed in 1925 from a number of major companies that had been working together closely since World War I...

, which was a partial owner of Norsk Hydro, had ordered 100 kg (220 lb)/month; Norsk Hydro′s maximum production rate was then limited to 10 kg (22 lb)/month.

In 1940, the "Deuxième Bureau
Deuxième Bureau
The Deuxième Bureau de l'État-major général was France's external military intelligence agency from 1871 to 1940. It was dissolved together with the Third Republic upon the armistice with Germany...

" (French military intelligence) directed three French agents—Captain Muller and Lieutenants Mossé and Knall-Demars—to remove the world′s extant supply, 185 kg (408 lb) of heavy water from the plant in Vemork in then-neutral Norway. The Norsk Hydro General Director, Axel Aubert
Axel Aubert
Axel Aubert was a Norwegian businessman.He was born in Kristiania. He took his engineer's education in that city in 1893, as well as a doctorate in chemistry Basel in 1895. He became the managing director of Engene Dynamitfabrik and Norsk Sprængstofindustri. In 1926 he was hired as...

, agreed to loan the heavy water to France for the duration of the war, observing that if Germany won the war, he was likely to be shot. Transportation was difficult as German Military Intelligence (the Abwehr
Abwehr
The Abwehr was a German military intelligence organisation from 1921 to 1944. The term Abwehr was used as a concession to Allied demands that Germany's post-World War I intelligence activities be for "defensive" purposes only...

) maintained a presence in Norway and had been alerted of ongoing French activities in Norway (although they had not been specifically warned about heavy water). Had they become aware of the shipment, they might have attempted to intercept it. The French transported it secretly to Oslo
Oslo
Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King...

, to Perth
Perth, Scotland
Perth is a town and former city and royal burgh in central Scotland. Located on the banks of the River Tay, it is the administrative centre of Perth and Kinross council area and the historic county town of Perthshire...

, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

 and then to France.

When France was invaded the French nuclear scientist Jean Frédéric Joliot-Curie took charge of the material, hiding it first in a Banque de France vault and then in a prison. Joliot-Curie then moved it to Bordeaux, where it, plus research papers and most of the scientists (Joliot-Curie remained in France) boarded a British merchant ship called BROOMPARK. BROOMPARK was one of the many merchant ships who were involved in saving over 200,000 troops and civilians in the three weeks after Dunkirk. The ship already had industrial diamonds, machinery and a number of British evacuees aboard. BROOMPARK delivered her passengers and cargo, together with all of the free supply of heavy water, to Falmouth on 21 June. The award of an OBE to Captain Paulsen was recorded in the London Gazette of 4 February 1941.

Although the ready inventory of heavy water was removed, the plant remained capable of producing heavy water. In investigations of collaboration launched by Norwegian authorities after the war, Norsk Hydro management′s collaboration with the Germans was considered. General Director Aubert′s cooperation with the French aided the Norsk Hydro case.

Operations Grouse and Freshman


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 they were in place a party of British engineers would be landed by military glider
Military glider
Military gliders have been used by the military of various countries for carrying troops and heavy equipment to a combat zone, mainly during the Second World War. These engineless aircraft were towed into the air and most of the way to their target by military transport planes, e.g...

 to attack the plant itself.

On 19 October 1942, a four-man team of Special Operations Executive
Special Operations Executive
The Special Operations Executive was a World War II organisation of the United Kingdom. It was officially formed by Prime Minister Winston Churchill and Minister of Economic Warfare Hugh Dalton on 22 July 1940, to conduct guerrilla warfare against the Axis powers and to instruct and aid local...

 (SOE)-trained Norwegian commandos
Norwegian resistance movement
The Norwegian resistance to the occupation of Norway by Nazi Germany began after Operation Weserübung in 1940 and ended in 1945. It took several forms:...

 parachuted into Norway. From their drop point in the wilderness they had 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 prior failures, included the team studying and memorizing blueprints.

Once the Norwegian Grouse team managed to make contact with the British, the British were suspicious, as they had not heard from the SOE team for a long time: they had 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 the Norwegian team′s insertion, and the next phase of operations commenced.

On 19 November 1942, Operation Freshman followed with the planned glider-borne landing on frozen lake Møsvatn
Møsvatn
Møsvatn is twelfth largest lake in Norway with a surface area of 78.31 km². It lies primarily in Vinje municipality in Telemark county. The lake lies in the watershed of the Skien river and discharges into the Måna river. Along the shores of the lake, many traces of stone age settlers can be...

 near the plant. Two Airspeed Horsa
Airspeed Horsa
The Airspeed AS.51 Horsa was a British World War II troop-carrying glider built by Airspeed Limited and subcontractors and used for air assault by British and Allied armed forces...

 gliders, towed by Handley Page Halifax
Handley Page Halifax
The Handley Page Halifax was one of the British front-line, four-engined heavy bombers of the Royal Air Force during the Second World War. A contemporary of the famous Avro Lancaster, the Halifax remained in service until the end of the war, performing a variety of duties in addition to bombing...

 bombers, each glider carrying two pilots and 15 Royal Engineers
Royal Engineers
The Corps of Royal Engineers, usually just called the Royal Engineers , and commonly known as the Sappers, is one of the corps of the British Army....

 of the 9th Field Company, 1st British Airborne Division, took off from RAF Skitten near Wick
Wick, Highland
Wick is an estuary town and a royal burgh in the north of the Highland council area of Scotland. Historically, it is one of two burghs within the county of Caithness, of which Wick was the county town. The town straddles the River Wick and extends along both sides of Wick Bay...

 in Caithness
Caithness
Caithness is a registration county, lieutenancy area and historic local government area of Scotland. The name was used also for the earldom of Caithness and the Caithness constituency of the Parliament of the United Kingdom . Boundaries are not identical in all contexts, but the Caithness area is...

. The towing of gliders had always been hazardous, but in this case it was made worse by the long flying distance to Norway and poor weather conditions which severely restricted visibility. One of the Halifax tugs crashed into a mountain, killing all seven aboard; its glider was able to cast off, but crashed nearby, resulting in several casualties. The other Halifax arrived at the area of the landing zone, but although the conditions had substantially improved it was impossible to locate the landing zone itself, owing 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. Shortly afterward, however, 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
Gestapo
The Gestapo was the official secret police of Nazi Germany. Beginning on 20 April 1934, it was under the administration of the SS leader Heinrich Himmler in his position as Chief of German Police...

, who tortured them during interrogation (not sparing the badly injured) and later had them executed under Adolf Hitler
Adolf Hitler
Adolf Hitler was an Austrian-born German politician and the leader of the National Socialist German Workers Party , commonly referred to as the Nazi Party). He was Chancellor of Germany from 1933 to 1945, and head of state from 1934 to 1945...

′s Commando Order
Commando Order
The Commando Order was issued by Adolf Hitler on 18 October 1942 stating that all Allied commandos encountered by German forces in Europe and Africa should be killed immediately, even if in uniform or if they attempted to surrender...

.

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
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...

 and lichen
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...

 during the winter until, just before Christmas
Christmas
Christmas or Christmas Day is an annual holiday generally celebrated on December 25 by billions of people around the world. It is a Christian feast that commemorates the birth of Jesus Christ, liturgically closing the Advent season and initiating the season of Christmastide, which lasts twelve days...

, a reindeer
Reindeer
The reindeer , also known as the caribou in North America, is a deer from the Arctic and Subarctic, including both resident and migratory populations. While overall widespread and numerous, some of its subspecies are rare and one has already gone extinct.Reindeer vary considerably in color and size...

 was encountered.

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 16 February 1943, in Operation Gunnerside (named after the village
Gunnerside
Gunnerside is a village in Swaledale, North Yorkshire, England, situated between the River Swale and its tributary, Gunnerside Beck.Gunnerside Ghyll , a smaller valley running northwards, at right angles to the Swale valley , was the site of a major lead mining industry in Swaledale until the late...

 where SOE head Sir Charles Hambro
Charles Jocelyn Hambro
Air Commodore Sir Charles Jocelyn Hambro, KBE, MC was a merchant banker and intelligence officer.-Career:He was born into a banking family of Danish origin which had settled in Dorset and the City of London in the early 19th century. He was the son of Charles Eric Hambro, a partner in C. J...

 and his family used to shoot grouse), an additional six Norwegian commandos were dropped by parachute by a Halifax bomber
Handley Page Halifax
The Handley Page Halifax was one of the British front-line, four-engined heavy bombers of the Royal Air Force during the Second World War. A contemporary of the famous Avro Lancaster, the Halifax remained in service until the end of the war, performing a variety of duties in addition to bombing...

 of 138 Squadron from RAF Tempsford
RAF Tempsford
RAF Tempsford in Bedfordshire, England was perhaps the most secret Royal Air Force airfield in World War II. It was home to the Special Duties Squadrons, No. 138, which dropped Special Operations Executive agents and their supplies into occupied Europe, and No...

. They were successful in landing, and encountered the Swallow team after a few days of searching on cross country skis. The combined team made final preparations for their assault, which was to take place on the night of 27/28 February 1943.

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, the Germans put mines, floodlights, and additional guards around the plant. While 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 m (656.2 ft) 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
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

, 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
Submachine gun
A submachine gun is an automatic carbine, designed to fire pistol cartridges. It combines the automatic fire of a machine gun with the cartridge of a pistol. The submachine gun was invented during World War I , but the apex of its use was during World War II when millions of the weapon type were...

 was purposely left behind to indicate that this was the work of British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 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.

The raid was considered successful. The entire inventory of heavy water produced during the German occupation, over 500 kg (1,102 lb), was destroyed along with equipment critical to operation of the electrolysis chambers. Although 3,000 German soldiers were dispatched to search the area for the commandos, all of them escaped; five of them skied
Ski warfare
Ski warfare, the use of ski-equipped troops in war, is first recorded by the Danish historian Saxo Grammaticus in the 13th century. The speed and distance that ski troops are able to cover is comparable to that of light cavalry.-History:...

 400 kilometres to Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

, two proceeded to Oslo where they assisted Milorg
Milorg
Milorg was the main Norwegian resistance movement in World War II....

, and four remained in the region for further work with the resistance.

Resumed operation and British air raids


While this attack did no irreparable damage to the plant, it did stop production for several months. The Vemork plant was restored by April and SOE concluded that a repeat raid would be extremely difficult, as German security had been considerably improved.

Almost as soon as production restarted, the USAAF
United States Army Air Forces
The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....

 started a series of raids on Vemork. In November, the plant was attacked by a massed daylight bombing raid of 143 B-17 heavy bomber
Heavy bomber
A heavy bomber is a bomber aircraft of the largest size and load carrying capacity, and usually the longest range.In New START, the term "heavy bomber" is used for two types of bombers:*one with a range greater than 8,000 kilometers...

s dropping 711 bombs, of which at least 600 missed the plant. The damage, however, was quite extensive. The need for ground assaults was reduced from a year earlier as there was now an available alternative of night bombing, which had previously been unrealistic owing to German air cover. The Germans were convinced that air raids would result in further serious "hits", and they decided to abandon the plant and move remaining stocks and critical components to Germany in 1944.

Sinking the SF Hydro on Lake Tinnsjø



Knut Haukelid
Knut Haukelid
Knut Haukelid was a Norwegian resistance movement soldier during World War II, most notable for participating in the Norwegian heavy water sabotage...

, who was the only trained commando in the immediate area, was informed of the German plan to remove the heavy water and advised he would have to muster support and destroy the shipment. He 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 a half kilograms of plastic explosive with two alarm-clock fuses were fixed to the keel of the ferry, SF Hydro
SF Hydro
SF Hydro was a Norwegian steam powered railway ferry that operated on Tinnsjø in Telemark. The ferry operated between Mæl and Tinnoset between 1914 and 1944, connecting the two railways Rjukanbanen and Tinnosbanen. The railway was used to transport raw materials and fertilizer from Norsk Hydro's...

, 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 did not 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.

In 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 was not 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 was not searched for delayed charges. In the Hollywood Heroes of Telemark, the locomotive and train is shown, somewhat implausibly covered with German soldiers. In the Ray Mears BBC coverage, it is stated that in fact the General in command had ordered this specific disposition of troops.

Unknown to the saboteurs, a "Plan B" had been established by the SOE, who arranged a second team to attack the shipment at Herøya
Herøya
Herøya is a peninsula in the municipality of Porsgrunn, Norway. It is located between the fjords of Frierfjord to the west and Gunneklevfjord to the east, at the mouth of Telemarksvassdraget...

 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
Operation Alsos
Operation Alsos was an effort at the end of World War II by the Allies , branched off from the Manhattan Project, to investigate the German nuclear energy project, seize German nuclear resources, materials and personnel to further American research and to prevent their capture by the Soviets, and...

 nuclear seizure force.

Historical perspective


Recent investigation of production records at Norsk Hydro and analysis of an intact barrel that was salvaged in 2004 revealed that although the barrels in this shipment contained water of pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 14 — indicative of the alkaline electrolytic refinement process — they did not contain high concentrations of D2O. Despite the apparent size of shipment, the total quantity of pure heavy water was limited, with most barrels only containing between 1/2–1% pure heavy water, confirming the success of the Operation Gunnerside raid in destroying the higher purity heavy water. Deuterium represents only 0.015% of the hydrogen in water and must be enriched to greater than 99% for use in a reactor. The Germans would have needed a total of about 5 t (5.5 ST) of heavy water to get a nuclear reactor running; while the manifest indicated that there was only 0.5 t (0.551155655462194 ST) of heavy water being transported to Germany. Hence the Hydro was carrying too little heavy water to supply one reactor, let alone the 10 or more tons of heavy water needed to make enough plutonium for a nuclear weapon.

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 had the Norwegian heavy water been produced and shipped at the maximum rate. 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
Einar Skinnarland
Einar Skinnarland DCM was a Norwegian resistance fighter during the Second World War.Einar Skinnarland was born in Vinje, in Telemark county, Norway...



The Grouse/Swallow Team
Jens Anton Poulsson
Arne Kjelstrup
Arne Kjelstrup
Arne Kjelstrup, MM was a Norwegian resistance member during World War II, especially noted for his role in the heavy water sabotage 1942–1943, and for being military leader of Milorg section D-161 during the anti-demolition operation Sunshine 1944–1945.-Personal life:Kjelstrup was...

Knut Haugland
Knut Haugland
Knut Magne Haugland, DSO, MM, was a resistance fighter and noted explorer from Norway who accompanied Thor Heyerdahl on his famous 1947 Kon-Tiki expedition.-Early life and World War II:...

Claus Helberg
Claus Helberg
Claus Helberg was a Norwegian resistance fighter and mountain guide. He was a member of Company Linge, a resistance commando unit that was best known for carrying out Norwegian heavy water sabotage during World War II. After the war, he worked for the Norwegian Mountain Touring Association...



The Gunnerside Team
Joachim Holmboe Rønneberg
Joachim Rønneberg
Joachim Holmboe Rønneberg, DSO is a retired Norwegian officer and broadcaster. He is known for his resistance work during World War II and his post-war war information work.-Personal life:...

Knut Haukelid
Knut Haukelid
Knut Haukelid was a Norwegian resistance movement soldier during World War II, most notable for participating in the Norwegian heavy water sabotage...

Fredrik Kayser
Fredrik Kayser
Fredrik Thorbjørn Kayser, MM was a Norwegian resistance member during World War II. He was especially noted for his role in the Norwegian heavy water sabotage, and has been referred to as "Western Norway's Gunnar Sønsteby"....

Kasper Idland
Kasper Idland
Kasper Idland MM, was a Norwegian resistance member during World War II.-Early life and education:He was born in Figgjo, the second child of Karsten og Gudrun Berg Idland, and had seven siblings. He graduated as an army sergeant in 1937, after 3½ years at Hærens underoffisersskole at Gimlemoen,...

Hans Storhaug
Birger Strømsheim
(Leif Tronstad
Leif Tronstad
Leif Hans Larsen Tronstad DSO, OBE was a Norwegian scientist, intelligence officer and military organizer. He graduated from the Norwegian Institute of Technology in 1927 and was a prolific researcher and writer of academic publications...

) (planner, in the United Kingdom)


The Lake Tinnsjø Team
Knut Haukelid
Knut Haukelid
Knut Haukelid was a Norwegian resistance movement soldier during World War II, most notable for participating in the Norwegian heavy water sabotage...

, alias "Bonzo"
Rolf Sørlie (local resistance)
Einar Skinnarland
Einar Skinnarland
Einar Skinnarland DCM was a Norwegian resistance fighter during the Second World War.Einar Skinnarland was born in Vinje, in Telemark county, Norway...

 (base wireless operator)
Gunnar Syverstad
Gunnar Syverstad
Gunnar Bryde Syverstad was a Norwegian resistance member. He is known for his assistance at the Norwegian heavy water sabotage....

 (plant lab assistant)
Kjell Nielsen (plant transport manager)
(“Larsen”) (senior plant engineer)
(NN) (car procurer and driver)

Video and book coverage


A 1948 Norwegian movie based on Operations Freshman and Grouse, called Kampen om tungtvannet, features performances by at least four of the original participants in the raid.

A 1965 Hollywood movie based on the Operation Gunnarside raid, titled The Heroes of Telemark
The Heroes of Telemark
The Heroes of Telemark is a 1965 war film directed by Anthony Mann based on the true story of the Norwegian heavy water sabotage during World War II...

.
It features a performance by one of the original participants in the raid - as the Nazi pursuer of the escapees.

A 1966 book by František Běhounek
František Behounek
František Běhounek was a Czech scientist , explorer and writer.The asteroid 3278 Běhounek is named after him.- Biography :Běhounek studied physics and mathematics at Charles University, later radiology in France at Marie Curie-Skłodowska. In 1920s, he was one of the founders of State Radiological...

, titled Rokle u Rjukanu (Gorge at Rjukan), is a fiction inspired by the events.

On November 8, 2005, the Corporation for Public Broadcasting
Corporation for Public Broadcasting
The Corporation for Public Broadcasting is a non-profit corporation created by an act of the United States Congress, funded by the United States’ federal government to promote public broadcasting...

 - WGBH Educational Foundation aired a program which documented the work of a team of underwater archaeologists exploring the sunken ferry, SF Hydro in Lake Tinnsjø.

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
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

 television documentary series, The Real Heroes of Telemark, which sticks more to the facts than the Hollywood film it is named after. It also describes the survival aspects of the attack — how to survive for months in a mountain cabin.

The book Skis Against the Atom (ISBN 0-942323-07-6) is a first-hand account by Knut Haukelid
Knut Haukelid
Knut Haukelid was a Norwegian resistance movement soldier during World War II, most notable for participating in the Norwegian heavy water sabotage...

, one of the GUNNERSIDE raiders who stayed behind.

Jens-Anton Poulsson (SWALLOW/GROUSE) has told the story in the book The Heavy Water Raid: The Race for the Atom Bomb 1942-1944, Orion forlag As (2009), ISBN 978-82-458-0869-8.

The ill fated Operation FRESHMAN is covered extensively in two books: Richard Wiggan's Operation Freshman: The Rjukan Heavy Water Raid 1942, William Kimber & Co Ltd (1986), ISBN 978-0718305710, and the more recent, Jostein Berglyd's Operation Freshman: The Actions and the Aftermath, Leandoer & Ekholm (2007), ISBN 978-9197589598.

The raid is also the subject of the book, Assault in Norway: Sabotaging the Nazi Nuclear Program by Thomas Gallagher, published by Lyons Press (2002), ISBN 978-1-58574-750-4. This book is based on the author′s interviews with many of the commandos.

The games Blazing Angels Squadrons of WWII, Battlefield 1942: Secret Weapons of WWII
Battlefield 1942: Secret Weapons of WWII
Battlefield 1942: Secret Weapons of WWII is the second of two expansions to the World War II first-person shooter computer game Battlefield 1942. It is developed by Digital Illusions CE and published by Electronic Arts for Microsoft Windows September 4, 2003 in North America and September 5, 2003...

 and Medal of Honor
Medal of Honor (video game)
Medal of Honor is the first title in the long-running Medal of Honor series of video games. It was released for the PlayStation in November 1999...

 each include missions involving the destruction of the heavy water plant.

On their 2010 album Coat of Arms
Coat of arms
A coat of arms is a unique heraldic design on a shield or escutcheon or on a surcoat or tabard used to cover and protect armour and to identify the wearer. Thus the term is often stated as "coat-armour", because it was anciently displayed on the front of a coat of cloth...

, Swedish power metal
Power metal
Power metal is a style of heavy metal combining characteristics of traditional metal with speed metal, often within symphonic context. The term refers to two different but related styles: the first pioneered and largely practiced in North America with a harder sound similar to speed metal, and a...

 band Sabaton
Sabaton (band)
Sabaton is a Grammis-nominated power metal band from Falun, Sweden formed in 1999. The band's main lyrical themes are those of historical wars. This is heard in albums Primo Victoria, Attero Dominatus and Coat of Arms where all of the songs, except final tracks, take inspiration from historical...

has a song named "Saboteurs", detailing the operation.

External links