Norwegian heavy water sabotage
Norwegian heavy water sabotage (Bokmål: Tungtvannsaksjonen,
Nynorsk: Tungtvassaksjonen) was a series of operations undertaken by
Norwegian saboteurs during
World War II
World War II to prevent the German nuclear
weapon project from acquiring heavy water (deuterium oxide), which
could have been used by the Germans to produce nuclear weapons. In
1934, at Vemork, Norway,
Norsk Hydro built the first commercial plant
capable of producing heavy water as a byproduct of fertilizer
production. It had a capacity of 12 tonnes per year. During World War
II, the Allies decided to remove the heavy water supply and destroy
the heavy water plant in order to inhibit the German development of
nuclear weapons. Raids were aimed at the 60 MW
station at the
Rjukan waterfall in Telemark, Norway.
Prior to the German invasion of
Norway on 9 April 1940, the Deuxième
Bureau (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 lend the
heavy water to France for the duration of the war. The French
transported it secretly to Oslo, to Perth, Scotland, 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 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 Grouse, Freshman, and
Gunnerside—finally managed to knock the plant out of production in
In Operation Grouse, the British
Special Operations Executive
Special Operations Executive (SOE)
successfully placed four Norwegian nationals as an advance team in the
region of the
Hardanger Plateau above the plant in October 1942. The
Operation Freshman was mounted the following month by
British paratroopers; they were to rendezvous with the Norwegians of
Operation Grouse and proceed to Vemork. This attempt failed when the
military gliders crashed short of their destination, as did one of the
Handley Page Halifax
Handley Page 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.
In February 1943, a team of SOE-trained Norwegian commandos succeeded
in destroying the production facility with a second attempt, 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, on Lake Tinn,
preventing the heavy water from being removed.
1 Technical background
1.1 Approaches to developing a weapon
Heavy water production
2 Operations to limit German access to heavy water
2.1 Pre-invasion efforts
2.2 Operations Grouse and Freshman
2.3 Operation Gunnerside
2.4 Resumed operation and Allied air raids
2.5 Sinking the SF Hydro
3 Historical perspective
4 SOE Norwegian agents involved
5 Published histories
6 Fiction, film, and video coverage
8 External links
The experimental apparatus with which the chemists
Otto Hahn and Fritz
Strassmann discovered nuclear fission of uranium in 1938
Enrico Fermi and his colleagues studied the results of bombarding
uranium with neutrons in 1934. The first person who mentioned the
idea of nuclear fission in 1934 was Ida Noddack. Four years after
the Fermi publication, in December 1938,
Lise Meitner and Otto Frisch
correctly interpreted the radiochemical experimental results of Otto
Fritz Strassmann as evidence of nuclear fission. News of this
discovery spread quickly among physicists and it was realised that if
chain reactions could be controlled, fission might lead to a new
source of great power. What was needed was a substance that could
"moderate" the energy of fission emitted (secondary) neutrons , so
that they could be captured by other fissile nuclei.
Heavy water and
graphite were the prime candidates for moderating the energy of
Nazi Germany investigated the production of an atomic bomb (see
German nuclear energy project), a range of options was 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
Plutonium-239 (239Pu) makes an effective weapons material (although
requiring an implosion-type mechanism as a simpler Thin Man gun-type
bomb is not feasible).
Heavy water has been demonstrated as an effective moderator for 239Pu
Heavy water may be separated from ordinary water by electrolysis.
Approaches to developing a weapon
In nuclear weapon development, the main problem is securing sufficient
"weapons grade" material. In particular, it is difficult to acquire
either fissile isotopes of uranium-235 (235U) or of 239Pu. Weapons
grade uranium requires mining, extracting and enriching natural ore.
Alternatively, plutonium can be "bred" in reactors fueled by
unenriched uranium, which requires chemical separation of the 239Pu
Unlike the Allies, who pursued both the enrichment of uranium and the
production of plutonium, German scientists only focused on plutonium
production, as this method was less expensive.
Although the most common isotope of uranium, uranium-238 (238U), can
be used as secondary fissionable material in hydrogen bombs, it cannot
be used as the primary fissile material for an atomic bomb.238U can be
used to produce 239Pu, through the fission of 235U which 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-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
Heavy water production
Heavy water made by Norsk Hydro
In normal water, there is only one deuterium atom for every 6400
hydrogen atoms, but deuterium is more prevalent in the residue of
water used as an electrolyte. An analysis of the residues from the
Vemork hydroelectric plant, a large-scale hydrogen production plant
using electrolysis of water for ammonia production, showed a
hydrogen/deuterium ratio of 48, most of the deuterium being bound in
HDO molecules. Leif Tronstad, then a lecturer at the Norwegian
Institute of Technology 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
normal 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 by-product of fertilizer
production, for which the ammonia was used.
Hans Suess was a German adviser to the production of heavy water.
Suess had assessed the
Vemork plant as being incapable of producing
militarily useful quantities of heavy water in less than five years at
its then capacity.
Operations to limit German access to heavy water
French research considered production of 239Pu using reactors
moderated by both heavy water and graphite. 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 Farben, 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
In 1940, the "Deuxième Bureau" (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
Vemork plant in then-neutral
Norsk Hydro General Director, Axel Aubert, agreed to lend
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) maintained a
Norway and had been alerted of ongoing French activities
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,
Perth, Scotland and then to France.
When France was invaded the French nuclear scientist 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 the British tramp steamer
Broompark, which was one of the many merchant ships 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. SS Broompark delivered its
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. Crucial to the
success of the mission was the role played by Charles Howard, 20th
Earl of Suffolk.
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
Operations Grouse and Freshman
Main article: Operation Freshman
Rjukan between lakes
Møsvatn (west, upstream) and Lake
Operations for the destruction of the
Vemork plant were mounted by the
Combined Operations Headquarters
Combined Operations Headquarters starting in October 1942. The plan
consisted of two operations: the first would drop a number of
Norwegian locals into the area as an advance force (Operation Grouse),
and once they were in place a party of British engineers would be
landed by military glider to attack the plant itself (Operation
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 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's studying and memorising blueprints.
After the delays, 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 near the plant. Two
Airspeed Horsa gliders, towed by
Handley Page Halifax
Handley Page Halifax bombers, each
glider carrying two pilots and 15
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 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 afterwards, 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, who
tortured them during interrogation (not sparing the badly injured) and
later had them executed under Adolf 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 surviving 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 reconstruction of the Operation
Gunnerside team planting explosives
to destroy the cascade of electrolysis chambers
British authorities were aware the Grouse team was still operational,
and decided to mount another operation in concert with them. By this
time the original Grouse team was being referred to as Swallow. On the
night of 16 February 1943, in Operation
Gunnerside (named after the
village where SOE head Sir Charles Hambro and his family 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 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, which was conducting exercises in the area. The container was
brought back to England and was displayed in the Airborne Museum at
Aldershot. The museum closed in 2008 and is now part of the Imperial
War Museum Duxford.
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 m (246 ft) bridge spanning the deep ravine, 200 m
(660 ft) above the river Måna, 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 levelled, 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 Thompson 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 try to avoid reprisals. A
bizarre 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
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 400 kilometres to Sweden, two proceeded to
Oslo where they assisted Milorg, and four remained in the region for
further work with the resistance.
Resumed operation and Allied air raids
Although 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 commando raid would be extremely
difficult, as German security had been considerably improved.
Almost as soon as production restarted, the USAAF started a series of
raids on Vemork. In November, the plant was attacked by a massed
daylight bombing raid of 143 B-17 heavy bombers dropping 711 bombs, of
which at least 600 missed the plant. The damage, however, was quite
Then, on 16 and 18 November 35 B-24 heavy bombers from the 392nd
Bomber Group based in Wendling, Station 118, attacked the
hydro-electric power station at
Rjukan with excellent coverage of the
target. These missions were the longest for this bomber group, lasting
9 1/2 and 10 1/2 hours respectively.
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
Main article: SF Hydro
SF Hydro at
Mæl in 1925
Knut Haukelid, 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
recruited two people. They decided to sabotage a ferry that would be
carrying the heavy water across Lake Tinn. One of the people he
recruited 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, which was to carry the railway cars with the heavy
water drums across Lake Tinn. 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 film
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
the first attempt fail. The disassembled factory was later found in
southern Germany during the closing stages of the war by members of
Alsos Mission nuclear seizure force.
The Hydroelectric Plant in 2008. The Hydrogen Production Plant
building was demolished in 1977.
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 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
in destroying the higher purity heavy water. The Germans would have
needed a total of about 5 t (5.5 short tons) of heavy water to
get a nuclear reactor running; while the manifest indicated that there
was only 500 kg (0.55 short tons) 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 if the Norwegian heavy water had 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
The Grouse/Swallow Team
Joachim Holmboe Rønneberg
(Leif Tronstad) (planner, in the United Kingdom)
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)
Source: Bascomb, Neal (3 May 2016). The Winter Fortress: The Epic
Sabotage Hitler's Atomic Bomb. Houghton Mifflin Harcourt.
pp. xiv–xv. ISBN 9780544368064. Retrieved 15 February
As of November 2015, Joachim Rønneberg, age 96, was the last
surviving member of the
Gunnerside team. The New York Times reported
that Rønneberg was "still mentally sharp at his advanced age and
still possessed of the unflappable calm that so impressed British
military commanders more than 70 years ago".
A 1962 book by John D. Drummond, titled But For These Men
(ISBN 0705700453), tells a true account of two dramatic raids:
one on the
Norsk Hydro heavy water factory at Vemork, and another on
the railway ferry "Hydro" to destroy Germany's heavy water production
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 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, one of the
Gunnerside raiders who
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.
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 978-0-7183-0571-0, and
the more recent, Jostein Berglyd's Operation Freshman: The Actions and
the Aftermath, Leandoer & Ekholm (2007),
Richard Rhodes's Pulitzer Prize-winning book The Making of the Atomic
Bomb includes details on the events in chapters 14–15.
Leo Marks' 1998 book Between Silk and Cyanide: A Codemaker's Story
1941–1945 covers the story in some detail. Marks was SOE's
cryptographer. He knew the Norwegian team, trained them in
cryptography so they could communicate with SOE back in England, and
avidly followed their progress after they were dropped in Norway.
Published by HarperCollins. ISBN 0-684-86780-X
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.
An account of Operation
Gunnerside is told in The Winter Fortress: The
Epic Mission to
Sabotage Hitlers Atomic Bomb, by Neal Bascomb,
published by Houghton Mifflin (2016), ISBN 978-0-544-36805-7.
Damien Lewis's 2016 book Hunting Hitler's Nukes: The Secret Race to
Stop the Nazi Bomb, ISBN 978-1-78648-208-2, covers the raid and
the subsequent sinking of the
SF Hydro in detail.
Fiction, film, and video coverage
The première of Kampen om tungtvannet on 5 February 1948. From left:
Knut Haukelid, Joachim Rønneberg,
Jens Anton Poulsson
Jens Anton Poulsson (shaking hands
with King Haakon VII), Kasper Idland.
A 1948 Norwegian film 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 British film based on the Operation
Gunnerside raid, titled The
Heroes of Telemark. It features a performance by one of the original
participants in the raid – as the Nazi pursuer of the escapees.
A 1966 book by Czech author František Běhounek, titled Rokle u
Rjukanu (Gorge at Rjukan), is a fiction inspired by the events.
A 1979 Canadian movie and TV-series titled A Man Called Intrepid,
based on the book of the same name by William Henry Stevenson. It
features David Niven,
Michael York and Barbara Hershey.
A late 2003 game by
Totally Games was released named Secret Weapons
Over Normandy, a fiction game which has its story based off real life
occurrences during World War II, features a segment which alludes to
the plant and attempted raids.
On 8 November 2005, the
Corporation for Public Broadcasting
Corporation for Public Broadcasting – WGBH
Educational Foundation in Boston, MA aired a program which documented
the work of a team of underwater archaeologists exploring the sunken
SF Hydro in Lake Tinn.
In 2013, for the 70th anniversary of Operation Gunnerside,
interviewed Joachim Rønneberg, the leader and last surviving member
A six-episode TV mini-series titled
The Heavy Water War (The Saboteurs
in the UK) tells the story with a particular emphasis on the role
of Leif Tronstad. This Norwegian-Danish-British co-production is in 6
episodes, the first of which was initially broadcast on 4 January
In the 2014 game Enemy Front, one of the main missions takes place
during the sabotage of the
Vemork Heavy Water Plant. During this
mission, the player is led by a character called "Lief Rønneberg",
who is a homage to
Joachim Rønneberg and its involvement in Operation
Another fictionalization is The Saboteur, a 2017 novel by Andrew
Additionally there is a song by Swedish power metal band Sabaton
called 'Saboteurs' recalling the events of Operation Gunnerside.
^ a b c d e Dahl, Per F (1999).
Heavy water and the wartime race for
nuclear energy. Bristol: Institute of Physics Publishing.
pp. 103–108. ISBN 07 5030 6335. Retrieved 12 July
^ Foot, M.R.D. (October 1984). The
Special Operations Executive
BBC Books. ISBN 0-563-20193-2.
^ E. Fermi, E. Amaldi, O. D'Agostino, F. Rasetti, and E. Segrè (1934)
"Radioacttività provocata da bombardamento di neutroni III," La
Ricerca Scientifica, vol. 5, no. 1, pp. 452–453.
Ida Noddack (1934) "Über das Element 93," Zeitschrift für
Angewandte Chemie, vol. 47, no. 37, pp. 653–655.
^ Weintraub, Bob.
Lise Meitner (1878–1968): Protactinium, Fission,
and Meitnerium. Retrieved on 8 June 2009.
^ Bernstein, Jeremy (2007). Plutonium: A History of the World's Most
Dangerous Element. Joseph Henry Press. ISBN 0-309-10296-0.
Retrieved 12 July 2007.
^ Powers, Thomas (1993). Heisenberg's War: the secret history of the
German bomb. Alfred A. Knopf. ISBN 0-394-51411-4.
^ The heavy water concept was perfectly viable—one needs only
consider the heavy water moderated production reactors at Savannah
River Site's R-Reactor, P-Reactor, L-Reactor, K-Reactor, and
C-Reactor, or Mayak's production reactors, to see compelling proof
that heavy water is fully effective for plutonium production if
available in sufficient quantities.
^ Per F. Dahl (1999).
Heavy water and the wartime race for nuclear
energy. p. 43. ISBN 0-585-25449-4.
Vemork Heavy Water Plant – 1942–44". GlobalSecurity.org.
Archived from the original on 6 August 2009. Retrieved 15 July
^ Ebb and Flow, Evacuations and Landings by Merchant Ships in World
War Two, Roy Martin ISBN 0955744121
^ Andersen, Ketil Gjølme G. (2009). "
Axel Aubert – utdypning".
Store norske leksikon
Store norske leksikon (in Norwegian). Oslo: Kunnskapsforlaget.
Archived from the original on 19 September 2012. Retrieved 7 July
^ a b c d e f g h i Gallagher, Thomas (2002). Assault In Norway:
Sabotaging the Nazi Nuclear Program. Guilford, Connecticut: The Lyons
Press. ISBN 1-58574-750-5. Retrieved 12 July 2009.
^ a b c Berglyd, Jostein; Translated by Tim Dinan (2008). Operation
Freshman: The Hunt for Hitler's Heavy Water. Solna: Leandoer and
Eckholm. ISBN 978-91-975895-9-8. Retrieved 12 July 2009.
^ a b Riste, Olav; Nøkleby, Berit (1970).
Norway 1940–45: The
Resistance Movement. Oslo: Tano. ISBN 82-518-0164-8.
^ "Airborne Forces Museum in Aldershot". Airborne Assault ParaData.
Archived from the original on 4 February 2017. Retrieved 3 February
^ The Saboteurs of Telemark,
^ Crowdy, Terry (2008) SOE Agent:Churchill's Secret Warriors. pg 42
^ Bailey, Roderick (2008) Forgotten Voices of the Secret War: An
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& Schuster. ISBN 978-0-684-81378-3. Retrieved 12 July
^ http://www.b24.net Archived 16 February 2008 at the Wayback Machine.
The Official Website of the 392nd Bomb Group
^ Haukelid, Knut (1989). Skis against the atom. Minot, North Dakota:
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^ "Heroes of
Telemark accompany heavy water barrel to USA". Norsk
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^ a b "NOVA: Hitler's Sunken Secret". The Corporation for Public
Broadcasting – WGBH Educational Foundation. 1996–2005. Archived
from the original on 12 July 2009. Retrieved 12 July 2009.
^ a b
BBC TV documentary about the raid based on the survival skills,
who actually interviewed the saboteur / "pursuer"
^ "Kulturhistorisk Stedsanalyse For Og Hotodden Kommuner" (PDF).
p. 34. Archived from the original (PDF) on 9 September
^ a b NOVA (8 November 2005). "Hitler's Sunken Secret (transcript)".
NOVA Web site. Archived from the original on 17 September 2008.
Retrieved 8 October 2008.
^ "Archived copy". Archived from the original on 24 September 2017.
Retrieved 6 September 2017.
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Chance in Foiling Hitler's Nuclear Ambitions". The New York Times.
Retrieved 4 February 2016.
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Simon and Schuster. pp. 455–457, 512–517.
ISBN 9781439126226. Archived from the original on 9 September
^ "Kampen on tungtvannet". IMDb. Archived from the original on 29
January 2010. Retrieved 15 February 2009.
^ “A Man Called Intrepid” on IMDB
^ A Man Called Intrepid (1979) on IMDb
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helped stop Hitler's A-bomb".
BBC News. Archived from the original on
10 March 2016. Retrieved 4 February 2016.
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collaboration". The Guardian. Archived from the original on 21 July
2015. Retrieved 18 July 2015.
^ "Anna Friel, Frank Kjosås Board Norwegian
Sabotage TV Series".
Archived from the original on 21 July 2015.
^ "NRK ready to declare €8.7 million Heavy Water War". Archived from
the original on 23 September 2015.
^ "Trailer: The Heavy Water War". Archived from the original on 13
NOVA: Hitler's Sunken Secret
A slide show from a CNN report about the raids
Norsk Hydro's official site on
Rjukan during the war
Interview with Joachim Rønneberg
The Assault Glider Trust
Operation Freshman memorial at RAF Skitten
Operation Freshman roll of honour, awards and images
Annotated bibliography for
Norwegian heavy water sabotage
Norwegian heavy water sabotage from the
Alsos Digital Library for Nuclear Issues
British Commando raids of the Second World War
List of Commando raids on