ISSN:0029-5450    

DOI:10.13182/NT87-A34030

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Based on their proven high-temperature reactor (HTR) with pebble-bed core, Brown, Boveri&Cie/Hochtemperatur-Reaktorbau have developed an HTR-100 plant that combines favorable capital costs and high availability. Due to the high HTR-specific standards and passive safety features, this plant is especially well suited for siting near the end user. The safety concept permits further operation of the plant or decay heat removal via the operational heat sinks in the event of maloperation and design basis accidents having a higher probability of occurrence. In the event of hypothetical accidents, the decay heat is removed from the reactor pressure vessel by radiation, conduction, and convection to a concrete cooling system operating in natural convection. As an example of the new HTR-100 plant concept, a twin-block plant design for extraction of industrial steam is presented.

ISSN:0029-5450    

DOI:10.13182/NT87-A34031

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Kraftwerk Union AG has almost completed the development of a dedicated 200-MW(thermal) nuclear district heating plant to provide environmentally clean energy at a predictably low cost. The concept can easily be adapted to meet power requirements within the 100- to 500-MW(thermal) range. This technology is the product of the experience gained with large pressurized water reactor and boiling water reactor power plants, with respect to both plant and fuel performance. The major development task is that of achieving sufficiently low capital cost by tailoring components and systems designed for large plants to the specific requirements of district heating. These requirements are small absolute power, low temperatures and pressures, and modest load following, all of which result in the characteristics that are summarized. A fully integrated primary system with natural circulation permits a very compact reactor building containing all safety-related systems and components. Plant safety is essentially guaranteed by inherent features. The reactor containment is tightly fitted around the reactor pressure vessel in such a way that, in the event of any postulated coolant leak, the core cannot become uncovered, even temporarily. Shutdown is assured by gravity drop of the control rods mounted above the core. Decay heat is removed from the core by means of natural circulation via dedicated intermediate circuits of external aircoolers. The design work for systems, components, and structures has almost been completed. Detailed accident analyses have demonstrated that the plant’s safety characteristics are excellent.

ISSN:0029-5450    

DOI:10.13182/NT87-A34032

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Nuclear reactors of 200- to 400-MW(thermal) power for district heating are the subject of increasing interest, and several specific designs are under discussion today. In the Federal Republic of Germany (FRG), the Kraftwerk Union AG has presented a 200-MW(thermal) heating reactor concept. The main safety issues of this design are assessed. In this design, the primary system is fully integrated into the reactor pressure vessel (RPV), which is tightly enclosed by the containment. The low process parameters like pressure, temperature, and power density and the high ratio of coolant volume to thermal power allow the design of simple safety features. This is supported by the preference of passive over active components. A special feature is a newly designed hydraulic control and rod drive mechanism, which is also integrated into the RPV. Within the safety assessment an overview of the relevant FRG safety rules and guidelines, developed mainly for large, electricity-generating power plants, is given. Included is a discussion of the extent to which these licensing rules can be applied to the concept of heating reactors.

ISSN:0029-5450    

DOI:10.13182/NT87-A34033

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

With fossil fuel running out in the foreseeable future, it is essential to develop substitution strategies. The heat market in industrial countries in the Northern Hemisphere has two peaks. The dominant one occurs at∼90°C and is due to the energy demand for space heating and warm water production. A smaller peak, mainly for metallurgical processes, occurs at∼1300°C. From thermodynamics considerations, using the high flame temperature of fossil fuels–or electricity–to supply the lower temperature range is obviously wasteful. On the other hand, contemporary light water reactor (LWR) technology makes it feasible to provide the space heating sector with hot water in a district heating network. Basically, existing reactor systems are adequate for this. Some 40 to 50% of the heat demand arises in the range below 120°C, causing a corresponding fraction of air pollution by SO2and to a lesser extent NOx, if fossil fuels are used. When analyzing an adequate district heating system, units in the 10- to 50-MW power range are found to be most suitable for Switzerland, both with respect to network size and the democratic decision-making structure. They would have the best chance of penetrating and covering the heat market. In a cooperative effort among some members of Swiss industry and the Swiss Federal Institute for Reactor Research, a small LWR for heating purposes only is being developed. The Swiss Heating Reactor (SHR) is a small, 15-bar boiling water reactor. Its core, together with its primary heat exchanger, is located in a reactor pressure vessel and a shroud within an underground water pool. This pool acts both as an emergency heat sink and as a biological shield and has a steel-lined concrete containment. The pool is dimensioned to leave the concrete ultimately inactive. The built-in safety and reliability of the SHR are better than for conventional nuclear power reactors, and the admissible risk curve to an individual is set correspondingly low. The economic target of 100 to 120 Swiss franc/MW·h heat for consumers seems achievable.

ISSN:0029-5450    

DOI:10.13182/NT87-A34034

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

The SECURE heating reactor was designed by ASEA-ATOM as a realistic alternative for district heating in urban areas and for supplying heat to process industries. SECURE has unique safety characteristics, that are based on fundamental laws of physics. The safety does not depend on active components or operator intervention for shutdown and cooling of the reactor. The inherent safety characteristics of the plant cannot be affected by operator errors. Due to its very low environmental impact, it can be sited close to heat consumers. The SECURE heating reactor has been shown to be competitive in comparison with other alternatives for heating Helsinki and Seoul. The SECURE heating reactor forms a basis for the power-producing SECURE-P reactor known as PIUS (Process Inherent Ultimate Safety), which is based on the same inherent safety principles. The thermohydraulic function and transient response have been demonstrated in a large electrically heated loop at the ASEA-ATOM laboratories.

ISSN:0029-5450    

DOI:10.13182/NT87-A34035

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

A hydraulically driven control rod is being developed at Kraftwerk Union for integration in the primary system of a small nuclear district heating reactor. An elaborate test program, under way for∼3 yr, was initiated with a plexiglass rig to understand the basic principles. A design specification list was prepared, taking reactor boundary conditions and relevant German rules and regulations into account. Subsequently, an atmospheric loop for testing of components at 20 to 90°C was erected. The objectives involved optimization of individual components such as a piston/cylinder drive unit, electromagnetic valves, and an ultrasonic position indication system as well as verification of computer codes. Based on the results obtained, full-scale components were designed and fabricated for a prototype test rig, which is currently in operation. Thus far, all atmospheric tests in this rig have been completed. Investigations under reactor temperature and pressure, followed by endurance tests, are under way. All tests to date have shown a reliable functioning of the hydraulic drive, including a novel ultrasonic position indication system.

ISSN:0029-5450    

DOI:10.13182/NT87-A34036

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Optimization of fuel assembly exchange machine movements during periodic refueling outage is discussed. The fuel assembly movements during a fuel shuffling were examined, and it was found that the fuel assembly movements consist of two different movement sequences; one is the“PATH,”which begins at a discharged fuel assembly and terminates at a fresh fuel assembly, and the other is the“LOOP,”where fuel assemblies circulate in the core. It is also shown that fuel-loading patterns during the fuel shuffling can be expressed by the state of each PATH, which is the number of elements already accomplished in the PATH actions. Based on this fact, a scheme to determine a fuel assembly movement sequence within the constraint was formulated using the artificial intelligence language PROLOG. An additional merit to the scheme is that it can simultaneously evaluate fuel assembly movement, due to the control rods and local power range monitor exchange, in addition to normal fuel shuffling. Fuel assembly movements, for fuel shuffling in a 540-MW(electric) boiling water reactor power plant, were calculated by this scheme. It is also shown that the true optimization to minimize the fuel exchange machine movements would be costly to obtain due to the number of alternatives that would need to be evaluated. However, a method to obtain a quasi-optimum solution is suggested.

ISSN:0029-5450    

DOI:10.13182/NT87-A34037

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

The Caorso limit cycle data observed during the stability tests were analyzed by the three-dimensional transient code TOSDYN-2. The Caorso limit cycle oscillation was spatially out of phase, and both the amplitude and the extent of the large amplitude region were large. For this reason, it is very valuable for the qualification of the TOSDYN-2 code. TOSDYN-2 employs a three-dimensional neutronics model and a multichannel-type thermal-hydraulic model. The channel-type grouping is important for qualification analysis. It was determined by considering the test results and the more detailed three-dimensional steady-state code results. The analytical results imply that many unstable channels or unstable regions might exist separately in the core. To account for this, TOSDYN-2 could accurately simulate both the amplitude of the limit cycle oscillation and the spatial power change profile. Thus, TOSDYN-2 applicability to the spatial power change phenomenon has been well verified.

ISSN:0029-5450    

DOI:10.13182/NT87-A34038

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

The structural reliability of a fast breeder reactor cover was evaluated using probabilistic fracture mechanics. The effects of important factors (initial crack distribution, crack detection level, crack growth rate, incidence of events such as earthquakes, in-service inspection for cracks, weld toughness, residual stresses, and environmental effects) on the reliability of structures were estimated, and methods for maintaining proper reliability were studied. It was found that the probability of the reactor losing its function is∼10−8in the terminal stage of the plant lifetime, even when the most conservative initial crack distribution and crack detection level are assumed. However, the prerequisite of such a condition is the use of appropriate leak monitors or proper atmospheric control. It was also confirmed that the degree of improvement in reliability through in-service crack detection, which was considered to be important, is not necessarily significant for the reactor cover.

ISSN:0029-5450    

DOI:10.13182/NT87-A34039

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor