Yes he did. His experimental reactor at Stadtilm was a
heavy water moderated design and his job tiltles included
Commissioner for Norwegian HeavyWater Production

He was the scientific leader of Heavy water production in Norway and according
to his own testimony enough amounts of Heavy water arrived in Germany in
Aug/Sep 44 from Norway.
By the time the Heavy water from Norway arrived,it was no longer needed.He
failed, the reactor never achieved criticallity, ironically

however they did accidentally discover that they got
greater neutron miltiplication amongst the graphite blocks
sourrounding the reactor than with the uranium assembly
in the reactor itself. At last in Marc
1945 they had
stumbled on the fact that graphite could be used as a
moderator, far too late to use that

Strange,von Ardenne team reported as early as in Sep.42 that graphite could be
used as moderator alternative!.

No such seizure was made and the maximum production during the
war was around 140 kg per month

Yeah right,no such seizure ever made and also Saddam was about to build a
nuclear arsenal,German scientists forgat in 1945 what they knew in 1941,NV
Patrol boats attacked USS Maddox,Communists burned down Reichstag etc,etc.

No their period of original work came after the war when they
worked in the Soviet nuclear program.

No they were two of three most important scientists of German nuclear effort.
Guess what who has been ordered to built Soviet Bomb in Aug.45 by the Beria,A
soviet scientists or von Ardenne?.
(Obviously NKVD boss knew something about German bomb and its creators)
von Ardenne,knowing that he could never see Germany again if he accepted
Berias'offer and built a bomb for SU,diplomaticaly argued that soviet
scientists not germans should have leading role (federfuehrung) in making of
the soviet bomb,and germans should support them.That the reason why the soviet
bomb was built under sobiet management.

BTW ,Houtermans was a devoted Communist and anti-Nazi activist,he was in Soviet
Union before WWII and was put into jail during Stalins cleansing campaign.
When he (a German citizen) was arrested by Stalins henchmen,British gov't
protested and requested his immediate release,British protest was accompanied
by a threat of suspending commercial relations with SU.
After British protest he was released and went back to Germany,or more
precisely to Gestapo HQ.
Have you any idea why British gov't acted so for a German citizen and communist
jailed in Soviet Union?,

Actually the only German researcher who could have produced
a bomb was Paul Harteck who attempted to develop the
centrifuge enrichment process with virtually no official
backing.

Surely Harteck is one of founders of centrifuge enrichment technology and his
published studies are among thr best ,but in centrifuge technology Germany was
decades ahead of the rest of the world,there were many talents in this field
Zippe and Steenbeck for example.
Might be a little bit subjective,but I consider Dr.Zippe as the most important
contributor to centrifuge technology .