[en] Full text: As previously noted in the discussions concerning the methods used to provide or replace safety systems, most of the safety systems in the Al-Tuwaitha facility were severely damaged during the bombing, and it was considered too dangerous or difficult to repair or replace them. The condition of the site was such that even basic systems such as an electrical supply and containment structures were not available. As a consequence of the severe damage, essentially all of the entire site infrastructure required replacement. (author)

[en] There is provided a nuclear reactor installation comprising a fluid-cooled nuclear heat source, a primary pressure vessel containing the heat source, an outer envelope enclosing the primary pressure vessel and constituting secondary containment means therefor and providing external-missile protection therefor, and a plurality of auxiliary-facility stations disposed outside the outer envelope, wherein the outer envelope comprises a lower wall portion surrounding the primary pressure vessel, an annular portion integral with the lower wall portion and extending outwardly therefrom, and an upper portion integral with the annular portion and extending over the annular portion and over the primary pressure vessel, the annular portion and the primary pressure vessel being formed with sealable vertical penetrations communicating with the respective auxiliary-facility stations and with the primary pressure-vessel interior respectively and there being provided, in the said upper portion, handling means for lifting reactor components vertically through such penetrations and transporting them over the said annular portion and the primary pressure vessel

No abstract available

[en] For the first time, this paper presents and compares the experimental, long-term data of former HDR-containment blowdown experiments CONW and COND, tests V21.1 and V43, and the small-break, long-term blowdown experiments RBE and CON, tests T30.4 and T31.6 from Phases 1 and 2 of the HDR Safety Program in the large-scale HDR-Containment in Germany. The four experiments examined and evaluated in this paper cover the following changes in important parameters: (1) break size; (2) type of blowdown (subcooled water, steam); (3) break position with respect to its axial location in the containment; and (4) operation of Engineered Safety Features (ESF), such as internal spray. Results will be compared and conclusions will be drawn for: (1) vertical temperature distributions; (2) transverse temperature distributions; and (3) convective flows and global natural circulations. The review of the data base indicates the existence of large-scale global natural circulations which have the potential--depending on some conditions--to mitigate and homogenize non-uniform H₂-concentration distributions

[en] During 15 years of containment experiments in the large-scale, close-to-realistic HDR-containment for the German federally-funded HDR Safety Program, Phases 1 through 3, a large data base of DBA LOCA experiments with subcooled liquid and steam blowdowns has been accumulated. In addition several experiments were performed with small break blowdowns. For both types of scenarios, some experiments were used to examine hydrogen mixing and distributions under a variety of different release and containment atmosphere conditions. This paper, as Part 2 of a series of two, presents an overview of the HDR experiment E11.5 thereby supplementing the information provided on previous HDR-DBA-LOCA experiments V21.1 and V43 as well as medium-sized and small-break LOCA-experiments, T30.4 and T31.6, respectively and the information provided in the companion paper on HDR-experiment T31.5. The break position tested for experiment E11.5 was located in the lower-most part of the HDR containment. This experiment concluded the severe-accident-oriented test series E11 and constitutes a bridge to the previous DBA-oriented LOCA-experiments performed with release positions in the middle section (V21.1 and V43) and upper containment region (T31.5). This paper focuses on the transient long-term spatial evolutions of the relevant containment atmosphere conditions, including light gas mixture distribution

No abstract available

[en] The Project has undertaken design studies of concepts capable of providing added containment safety margins. Since the events, for which these features provide consequence reductions, are beyond the design basis accident classification, the conceptual designs would not be designed as Engineered Safety Features. A final decision has not been made by the Department of Energy as to the disposition of this advice. It is the Project's plan to develop sufficient design details for these features that construction schedules and cost estimates can be formulated. This information supplemented by the continuing analytical and experimental program to assess the adequacy of FFTF containment margins will enable a decision to be made as to additional features to be added to FFTF and their schedule for implementation

[en] This reports contains: (1) an evaluation by Gilbert/Commonwealth (G/C) of the NucleDyne passive Containment System (PCS) as that conceptual design is applied to a Westinghouse, two loop, Pressurized Water Reactor; (2) an evaluation by Westinghouse of two questions about the impact of the PCS on the Nuclear Steam Supply System (NSSS), which were posed by G/C and best answered by an NSSS vendor; and (3) replies to both the Gilbert/Commonwealth report and the Westinghoue report by NucleDyne Engineering Corporation

[en] A study of the Kozloduy NPP Unit 2 containment improvement has been carried out. The following objectives are identified: to assess confinement tightness (local tests); to improve tightness; to perform the most urgent repair works; to develop global test procedures including leak tightness at nominal and reduced pressure, structural integrity test and venting flaps reliability test. Nine groups of potential leakage paths have been determined. The ventilation system has been found as the major source of expected leakage having 60 penetrations with size above 250 mm. Proposed modifications of the ventilation system include reduction of the number of inflow and suction valves, replacement of some valves with a better quality ones and installation of isolating valves. It is planned to transfer the experience and results of this study to the other WWER-440 units. 1 ref

[en] The behaviour is described of reactor containments in severe accidents in light water reactors as predicted in the NRC's NUREG-1150 study (USNRC 1987)