Heavy water is used in certain types of nuclear reactors, where it acts as a neutron moderator to slow down neutrons. The CANDU reactor uses this design. Light water also acts as a moderator but because light water absorbs more neutrons than heavy water, reactors using light water as moderator must use enriched uranium rather than natural uranium, otherwise criticality is impossible. Nations with heavy water moderated reactors, include: Canada, India, South Korea, Romania, Pakistan, Argentina and China.
C A N a d a D e u t e r i u m U r a n i u m r e a c t o r s
Romania has two nuclear reactors generating almost 20 percent of its electricity (first commercial nuclear power reactor began operating in 1996 and the second started up in May 2007). Cernavoda power plant was based on technology transfer from Canada (AECL), Italy and the USA, with Candu-6 heavy-water reactors. Both reactors are fueled with indigenous UO2 sinterizable powder manufactured at Uranium Ore Processing
Feldioara Plant (center Romania). Through Feldioara plant, Romania is the only country in Europe that produces fuel for
CANDU nuclear power plants.
Three more partially completed CANDU reactors exist on the same site. Units 3 and 4 were expected to be CANDU 6 reactors with a similar design to Unit 2 and will each have a capacity of 740 MW.
China General Nuclear (CGN) has been designated as the "selected investor" for the development of Units 3 and 4. A letter of intent has been signed to complete the two units. There are currently no plans to complete Unit 5 at this time. However, the possibility of finishing construction remains.
CANDU 6 is a safe technology with a successful track-record over the last decades. The heavy-water coolant is kept under pressure, allowing it to be heated to higher temperatures without boiling, much as in a
Pressurized Water Reactor.
Romania is a party to the
Nuclear Non-Proliferation Treaty (NPT) since 1970 as a non-nuclear weapons state. It is also member of the Nuclear Suppliers' Group. The Additional Protocol in relation to its safeguards agreements with the IAEA came into force in 2000. Romania signed the Comprehensive Nuclear-Test-Ban Treaty (CTBT) on September 24, 1996 and later ratified the CTBT on October 5, 1999.
Because they do not require uranium enrichment, heavy water reactors are of concern in regards to nuclear proliferation. The breeding and extraction of plutonium can be a relatively rapid and cheap route to building a nuclear weapon, as chemical separation of plutonium from fuel is easier than isotopic separation of U-235 from natural uranium. Among current and past nuclear weapons states, China, South Africa and Pakistan first built weapons using highly enriched uranium, while Israel and India used plutonium from heavy water moderated reactors (which "burn" natural uranium).
V V R - S a n d T R I G A f i s s i o n r e a c t o r s
While Romania had a nuclear research program since 1949, for the first decades it focused on the usage of radioactive isotopes in medicine and industry. The alleged
military research program (Danube Program, started in 1978) was conducted at the
Măgurele Nuclear Research Institute *. The institute was equipped with a light water cooled / moderated reactor designed to produce neutron flux levels of ~2*10exp13 neutrons/cm3*sec using 4 / 5.6 kg. of U235 fuel (in 1957, a
VVRS fission reactor and a U120 cyclotron, both of Soviet origin, were put into service on the site). In 1997 the 2MW thermal power reactor was definitely shut-down. In 2003, Romania handed over to the IAEA 15 kg of highly enriched uranium fuel for the research reactor.
* The Măgurele Platform is a hub of physics and science. The construction and the commissioning of the Nuclear Research Reactor and the Cyclotron was followed shortly by the construction of the first Romanian electronic computing system (1957) and of the first laser in the country (1962), which is the third functional laser in the world (after the United States and Russia). Starting with 2013, ELI-NP (Extreme Light Infrastructure-Nuclear Physics) - a nuclear physics research center is built at Măgurele. The European project ELI will become the world’s most advanced global structure destined to studies related to photon radiation with extreme characteristics. The other two centers, namely ELI-Beamlines and ELI-ALPS, will be built in the Czech Republic and Hungary.
After the 1989 Romanian Revolution, Romania announced the International Atomic Energy Agency (IAEA) that it had 100 mg of plutonium separated in 1985 at the
Piteşti Nuclear Research Institute (founded in 1971, using a
TRIGA 14 MW pool type reactor, imported from US) and it allowed the IAEA full access to its facilities for inspection. TRIGA was originally designed to be fueled with highly enriched uranium but it was converted to enable use of low-enriched uranium fuel after 1989.
H e a v y W a t e r
Romania produces
heavy water at the Drobeta Girdler sulfide plant (the annual production is about 180 tons and the designed capacity of 360 tonnes/year - the largest capacity in the world). Since 2001 the ROMAG PROD become exporter of nuclear heavy water in South Korea, China, Germany, USA and Switzerland.
Heavy water is obtained from Danube River waters (1 kg of heavy water for approximately 300 tons of normal light water), which - as all surface continental waters, naturally contain a heavy water quantity of 0.0145%. This heavy water existing in natural water, is separated and enriched within ROMAG-PROD Plant up to a nuclear grade concentration of minimum 99.78%. The process of heavy water producing is based on isotopic exchange between water and hydrogen sulphide in bi-therm system, inside of Girdler-Sulphide plants, where a primary enrichment in Deuterium is reached up to approx 4-12%, based on the following reactions:
The primary enrichment is followed by a final concentration within a distillation under vacuum installation.
L i v i n g W a t e r
The by-product of the above mentioned process is the
Ultralight Water or
Deuterium-Depleted Water (
DDW); water which has a lower concentration of deuterium than occurs naturally. Production of ultralight water can result during electrolysis, distillation, and desalination. Filtration through special membranes and crystallization are also considered preparation methods. It can also be produced directly using the Girdler sulfide process.
Experiments have shown that consumption of light water may be beneficial as an adjunct to chemotherapy:
"Mice fed for 15 days with Deuterium-Depleted Water (30 ppm deuterium) had a statistically significant increased survival rate compared with control groups fed with normal distilled water (150 ppm deuterium), after 8.5 Gy irradiation (61% survival in the test group versus 25% in the control group). The hematological picture showed that normal WBC, RBC and platelet counts were maintained in the test groups. Immunological parameters (serum opsonic and bactericidal capacity, bactericidal capacity of the peritoneal macrophages) showed a marked increase in the test groups compared to a severe decrease in the control groups. Auxiliary tests using chemical radiomimetics (hydrochloric embihine) and immunosuppressors (cyclophosphamide) showed a strong protective effect of deuterium-depleted water against the decrease of the leukocyte counts and other immunologic parameters. In conditions of experimental inflammation induced with subcutaneous-implanted pellets, deuterium-depleted water feeding resulted in a statistically significant increase of the inflammatory response, demonstrated by increased percentages of PMN and lymphocytes in the peripheral blood and the increased phagocytic capacity of the peripheral blood PMN. Experimental infections induced with K. pneumoniae 506 and S. pneumoniae 558 in mice irradiated or treated with cyclophosphamide showed increased, non-specific immunity parameters. All results show a marked intensification of the immune defenses and increased proliferation of the peripheral blood cells, probably accounting for the radioprotective effects." (Romanian journal of physiology: physiological sciences; 1999 Jul-Dec)
"Deuterium-depleted water consumption integrated into conventional treatments resulted in a survival time of 26.6, 54.6, 21.9, and 33.4 months in the 4 patients, respectively. The brain metastasis of 2 patients showed complete response (CR), whereas partial response (PR) was detected in 1 patient, and the tumor growth was halted (no change or NC) in 1 case. The primary tumor of 2 patients indicated CR, and the lung tumor in 2 patients showed PR.
Conclusions: Deuterium-depleted water was administered as an oral anticancer agent in addition to conventional therapy, and noticeably prolonged the survival time of all 4 lung cancer patients with brain metastasis. We suggest that DDW treatment, when integrated into other forms of cancer treatment, might provide a new therapeutic option." (Integrative Cancer Therapies; 2008 Sep).
"The concentration of deuterium is about 150 ppm (over 16 mmol/L) in surface water and more than 10 mmol/L in living organisms. Experiments with deuterium depleted water (30+/-5 ppm) revealed that due to D-depletion various tumorous cell lines (PC-3, human prostate, MDA, human breast, HT-29, human colon, M14, human melanoma) required longer time to multiply in vitro. DDW caused tumor regression in xenotransplanted mice (MDA and MCF-7, human breast, PC-3) and induced apoptosis in vitro and in vivo. Deuterium depleted water (25+/-5 ppm) induced complete or partial tumor regression in dogs and cats with spontaneous malignancies, it was registered as anticancer for veterinary use in 1999 (Vetera-DDW-25 A.U.V., 13/99 FVM). The hypodermic preparation of the registered veterinary drug was successfully tested in clinical investigations. Under the permission of the Hungarian Institute of Pharmacology (No. 5621/40/95) a randomized, double blind controlled, human Phase II clinical trial with prostate cancer was performed, in compliance with GCP principles, which exhibited a significant difference between the control and treated groups with respect to the examined parameters, median survival time and the extension of life-span. We suggest that cells are able to regulate the D/H ratio and the changes in the D/H ratio can trigger certain molecular mechanisms having a key role in cell cycle regulation. We suppose that not the shift in the intracellular pH, but the concomitant increase in the D/H ratio is the real trigger for the cells to enter into S phase. The decrease of D concentration can intervene in the signal transduction pathways thus leading to tumor regression. Deuterium depletion may open new perspectives in cancer treatment and prevention helping to increase the effectiveness of current oncotherapies." (Orvosi Hetilap; 2010 Sep.).
Despite Gilbert Lewis' call in 1934 for such experiments, research on the effects of deuterium-depletion on living cells has been very limited with less than a dozen peer-reviewed research papers available via PubMed in mid-2011.
The most striking discovery was that tumour cells proved to be extremely sensitive to D-depletion, resulting in tumour regression and may even cause the necrosis of the tumour. On the other hand, healthy cells are able to adapt to the decreasing D-concentration. The growth rate of different tumourous cell lines in tissue culture (PC-3 human prostate-, MCF-7 and MDA human breast adenocarcinoma-, HT-29 human colon carcinoma-, A4 human leukaemia, as well as M14 human melanoma cells) was significantly inhibited in culture media containing DDW.
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