[en] Reactor vendors in most countries have had lean pickings for the past decade, and ordering seems unlikely to show much growth until the shock wave from the Chernobyl accident has died away. Paradoxically, however, at least one firm sees a niche in the market. ENACE - the Empresa Nuclear Argentina de Centrales Electricas, or Argentine Nuclear Power Plant Corporation - is stepping out into the market place with a newly-designed 380 MWe nuclear power plant. The plant is equipped with a pressurized heavy-water reactor of the pressure vessel type (PHWR). ENACE has adopted new boundary design conditions and has embodied a number of special features to assure safety and economy in operation. The major shareholder in ENACE is the Argentine National Atomic Energy Commission (CNEA). ENACE is the architect-engineer for the NPP projects of the Argentine nuclear programme. It has a licensing agreement with Siemens AG's Kraftwerk Union AG, which is its minor shareholder. Under this agreement, ENACE has the right to use the Siemens-KWU PHWR technology, which was originally developed for the MZFR reactor in the Federal Republic of Germany, as well as their know-how in pressurized (light-) water reactors (PWRs) design and construction. The CNEA also has agreements with Atomic Energy of Canada Ltd. for the transfer of technology related to CANDU-type PTHWRs. The CNEA and ENACE have acquired considerable practical experience from the construction and operation of the 367 MWe Atucha I PHWR and the 648 MWe Embalse PTHWR; ENACE is currently building Argentina's third nuclear power plant, Atucha II, a 745 MWe PHWR. (author)

[en] The KWU type PHWR was developed using natural uranium as fuel. Therefore, many design features of this reactor type are influenced by the principle of neutron economy. One characteristic is onpower refuelling and fuel shuffling. Excellent fuel utilization is also met with the pressure vessel concept of the KWU type PHWR allowing for low inventory of structural materials and maintaining high-purity of heavy water. Successful operation of the 367 MWsub(e) Atucha I power plant during the last 10 years has shown the achievement of commercial viability. The safety concept, in principle, is derived from the PWR technology, considering the special features of heavy water reactors. The high safety level is documented by risk studies. For many years KWU has been devoted to investigation on alternative fuel cycles with more efficiency in their use of uranium. In this paper the following main types of investigated fuel cycles are considered: Once-through natural uranium as the reference case. In this fuel cycle the uranium consumption of the PHWR is 80% of the consumption of thermal LWRs; Once-through cycle using low enriched uranium (LEU-cycle). This cycle offers further reduction of uranium consumption and increasing economy; Recycling of plutonium offers the advantage of reduced natural uranium consumption and lower fuel cycle costs without enrichment services; Recycling of thorium together with high enriched uranium as make-up fuel. This alternative offers further expanding of nuclear fuel resources; Tandem principle. Insertion of fuel assemblies consisting of fuel rods discharged from spent LWR assemblies. The technical concept of KWU's PHWRs does not require important changes on systems or components when changing from one fuel cycle to another. However, in many cases an optimum economical result can be achieved only when the design is made for a specific fuel alternative

[en] The design of the advanced KWU 745 MWe heavy water (D₂O) moderated and cooled pressurized water reactor (PHWR) bases on extraordinary successful operating plants with PHWR as well as pressurized light water reactors. The advanced 745 MWe PHWR, Atucha II, is under construction now and serves here as reference plant for the probabilistic evaluation. The objectives, approach, and results of the assessment are presented

[en] The PHWR plant Atucha II had to be evaluated via a probabilistic risk assessment (PRA) by KWU. This part of the paper describes the objective, the performance and the results of the analysis as well as the evaluation of the safety concept of the 745 MWe PHWR of KWU. (orig.)

[en] The safety concept for the KWU pressurized heavy-water reactor (PHWR) is based on the same features as that for the pressurized light-water reactor, e.g., reactor building consisting of a spherical steel containment and an outer concrete building with vented annulus in between. However, there are some specialities adherent to the PHWR. Safety related systems are designed to be both diverse and redundant. The moderator cooling system can be used as a high-pressure heat removal system, adding its effectiveness to the heat removal via the steam generators. For reactor shut-down a control rod system and a boron injection system exist independently. A safety evaluation has been performed via a probabilistic risk analysis. The assessed core damage frequency shows the same safety levels as with light-water reactors. The contribution of the different accident types proves the balance of the safety concept. The environment dose resulting from accidents is beyond a given dose frequency criterion. (orig.)

[en] The population of the world will duplicate within the next three to four decades. The primary energy consumption will increase accordingly. Considering the limited reach of our fossil energy resources and their negative impact on the global climate, alternative strategies for the power generation have to be developed. The contribution of the renewable energy sources will be important, but not sufficient, due to their high generation costs. The nuclear power, which already today participates essentially in the energy supply, will remain one of the most important options for environment protecting energy generation. Especially for the developing countries, which -in general- have currently a not covered energy demand, the build up of reasonable energy generation structures means enormous volumes of investments, which can only be financed with the assistance of the industrialized countries. Those, on the other hand, have to economize their energy consumption and have to undertake any effort in continuing with the development of clean, safe and competitive renewable resources. To provide increasing world population with sufficient energy and at the same time to reduce CO₂ emissions is one of the biggest challenges that mankind has ever faced. (Author)

[en] The safety concept of the PHWR is principally based on the same safety features as the light water PWR, e.g. reactor building consisting of a spherical steel containment and an outer concrete building with vented annulus inbetween. However, there are some specialities adherent to the heavy water reactor. Safety related systems are designed to be both, diverse and redundant. The moderator cooling system can be used as a high pressure heat removal sysem and thus is an addition to the heat removal via the steam generators. For reactor shut-down a control rod system and a boron injection system exist independently. (orig./HP)

[en] With ARGOS PHWR 380 a new concept of a pressure vessel, heavy water moderated power reactor with an electrical output of 380 MW is presented. Its main technical characteristics are very similar to those of the Atucha type reactor. The safety features, which are outlined in some detail, were established to meet all relevant international and national requirements. In particular, the moderator system can be used as a heat sink in a high pressure mode. (orig.)

[en] The Argentine nuclear power plant ARGOS PHWR 380 - or ARGentine Option for a Safe Pressurized Heavy-Water Reactor of 380 MW(e) - is briefly summarized and the new safety approaches used in its design are described. The paper presents the safety features for normal operation as well as the design criteria applied for potential accident situations. Great emphasis is given to the application of the demanding probabilistic safety requirements from the Argentinian regulatory authority. These include probabilistic safety criteria as well as specific requisites for performing the relevant probabilistic safety analyses. The description also includes the application of deterministic safety criteria both domestic and international, including the safety standards, guides and recommendations issued by the International Atomic Energy Agency. The paper also presents the special safety features incorporated in the design as an ultimate effort toward safety, namely a redundant high-pressure heat sink, improvements in auxiliary and emergency power supply, early and efficient detection of leakages from the primary boundary, and a vented containment. Finally, a short description of the possibilities of back-fitting is included. (author). 32 refs, 5 figs, 3 tabs

[en] The common design features between the pressurized heavy water reactor of Kraftwerk Union and a pressurized light water reactor are outlined. The first commercial power plant, with a 340 PHWR of KWU design is Atucha I which was handed over in 1974. The order for the 745 MWe Atucha II was accepted in October 1979. A description is given of the design of this plant and of the various safety engineering facilities. (U.K.)