Günter Lohnert - Academia.edu (original) (raw)
Papers by Günter Lohnert
In the very unlikely case of a core melt accident in a nuclear power plant, the reactor pressure ... more In the very unlikely case of a core melt accident in a nuclear power plant, the reactor pressure vessel could fail and corium melt could be released into the reactor cavity. A threat of the containment integrity could result. As a counter-measure the implementation of a core catcher device into nuclear power plants is envisaged. Such a core catcher concept
Das Vorhaben enthaelt folgende Themenkomplexe: 1) Untersuchungen zum Ausfall des Hauptwaermeueber... more Das Vorhaben enthaelt folgende Themenkomplexe: 1) Untersuchungen zum Ausfall des Hauptwaermeuebertragungssystems; 2) Kugelfliessen; 3) Programmentwicklung zur detaillierten Berechnung hypothetischer Stoerfaelle; a) Temperaturentwicklungscode THERMIX/RZKRIT (u.a. Anpassung an exotherme Waermequellen); b) Korrosionscode REACT/THERMIX (Anpassung zur Behandlung extrem grosser Lufteinbrueche in den Primaerkreis); c) Korrosionscode GRECO (Anpassung zur Behandlung extrem grosser Wassereinbrueche in den Primaerkreis); d) Transientencode KIND (Anpassung an extrem schnelle Transienten bei Reaktivitaetsstoerfaellen); 4) Begrenzungseinrichtungen fuer sicherheitstechnisch relevante Groessen; 5) Analysen zu hypothetischen Stoerfaellen; a) Hypothetische Lufteinbrueche; b) Belastung der Brennstoffpartikel bei schnellen Transienten. Die Problemstellung der einzelnen Aufgabenpakete werden erlaeutert und die erzielten wesentlichen Ergebnisse dargestellt. Die 8 Themenkomplexe sind einzeln in der Datenb...
Nuclear Engineering and Design, 2006
Nuclear Engineering and Design
The institute of nuclear engineering and energy systems (IKE), University of Stuttgart, Germany h... more The institute of nuclear engineering and energy systems (IKE), University of Stuttgart, Germany has developed a new thermal hydraulic tool which can be used for three-dimensional thermal hydraulic analysis of pebble bed as well as block type HTRs. During nominal operation, the flow inside the gas-cooled High Temperature Reactor is essentially INTRODUCTION Considering some criterion like optimal use of natural resources, proliferation resistance, nuclear safety excellence, cost saving, satisfying broader requirements (hydrogen production, desalination) etc, six systems are selected by the Generation IV International Forum as 4th generation nuclear system and two of the chosen six systems are gas cooled system [1]. The high temperature gas cooled reactor is considered as one of the most promising generation IV reactors due to its inherent safety performance as well as its high conversion efficiency due to higher outlet coolant temperature. For the assessment of the feasibility and saf...
Presentation des proprietes intrinseques de securite du reacteur a lit de boulets modulaire devel... more Presentation des proprietes intrinseques de securite du reacteur a lit de boulets modulaire developpe en Allemagne Federale
Transactions of the American Nuclear Society, 1979
... Publication Date, 1979 Jan 01. OSTI Identifier, OSTI ID: 6810626. Report Number(s), CONF-7905... more ... Publication Date, 1979 Jan 01. OSTI Identifier, OSTI ID: 6810626. Report Number(s), CONF-790519-. Other Number(s), Journal ID: CODEN: TANSA. Resource Type, Conference. Specific Type, Journal Article. Resource Relation, Journal ...
The temperature dependent, ideal gas scattering kernel for heavy nuclei with pronounced resonance... more The temperature dependent, ideal gas scattering kernel for heavy nuclei with pronounced resonances was developed, proved and implemented in the data processing code NJOY from which the scattering probability tables were prepared. Those tables were introduced to the well known MCNP code. The analytic solution of this scattering kernel is consistent with the Doppler Broadening method of D. E. Cullen and C. R. Weisbin. In this study we present an alternative stochastic algorithm based on MCNP subroutines which allows for Doppler broadening of the integral as well as double differential cross section. The analytical solution of the kernel is confirmed. This stochastic method is then introduced into the MCNP code by means of a rejection method, suggested originally by W. Rothenstein. The differences between the new kernel and the standard MCNP kernel are illustrated for specific resonances of U238, Th232, Au197 and Hg199. LWR unit cell calculations are performed and criticality, reaction...
Abstract The ingress of large amounts of water into the primary circuit of an HTR-Module represen... more Abstract The ingress of large amounts of water into the primary circuit of an HTR-Module represents the most severe hazard potential of that reactor plant. Nevertheless, the consequences of these accidents are shown to be practically negligible for the design basis accident and are still tolerable even for extreme hypothetical postulates. This benign behavior of the HTR-Module is due to many inherent properties which are especially designed into the nuclear steam supply system and will be explained in the paper. The core response due to the ingress of neutron moderating steam is discussed in detail and the consequences of the production of inflammable water gas by the chemical reaction of graphite and steam are shown. Concerning the environmental radiation hazard of the worst, still plausible hypothetical accident it is claimed that the radiation dose will not exceed the natural radiation dose accumulated over 50 years by more than an order of magnitude.
Nuclear Engineering and Design, 1988
To retain fission products after postulated accidents, power reactors usually rely on active safe... more To retain fission products after postulated accidents, power reactors usually rely on active safety systems inside the primary circuit, such as e.g. redundant shut down systems and multiple redundant decay heat removal systems. The HTR-Module is employing a different approach which relies entirely on the ability of the coated particle to retain all key radio-nuclides as long as a certain maximum fuel element temperature is not exceeded. Consequently, the reactor is designed such that for any postulated accident this maximum fuel element temperature is not reached even without relying on any active safety systems inside the primary circuit, since the decay heat can be removed to an outside heat sink solely by passive means. The paper discusses the experimental results of fission product release from spherical fuel elements for various temperatures. From the tests as well as from statistical considerations it can be concluded that any hazardous radiation dose to the environment can be excluded if the maximum fuel element temperature in the HTR-Module stays below 1600°C.
Nuclear Engineering and Design, 1990
In the very unlikely case of a core melt accident in a nuclear power plant, the reactor pressure ... more In the very unlikely case of a core melt accident in a nuclear power plant, the reactor pressure vessel could fail and corium melt could be released into the reactor cavity. A threat of the containment integrity could result. As a counter-measure the implementation of a core catcher device into nuclear power plants is envisaged. Such a core catcher concept
Das Vorhaben enthaelt folgende Themenkomplexe: 1) Untersuchungen zum Ausfall des Hauptwaermeueber... more Das Vorhaben enthaelt folgende Themenkomplexe: 1) Untersuchungen zum Ausfall des Hauptwaermeuebertragungssystems; 2) Kugelfliessen; 3) Programmentwicklung zur detaillierten Berechnung hypothetischer Stoerfaelle; a) Temperaturentwicklungscode THERMIX/RZKRIT (u.a. Anpassung an exotherme Waermequellen); b) Korrosionscode REACT/THERMIX (Anpassung zur Behandlung extrem grosser Lufteinbrueche in den Primaerkreis); c) Korrosionscode GRECO (Anpassung zur Behandlung extrem grosser Wassereinbrueche in den Primaerkreis); d) Transientencode KIND (Anpassung an extrem schnelle Transienten bei Reaktivitaetsstoerfaellen); 4) Begrenzungseinrichtungen fuer sicherheitstechnisch relevante Groessen; 5) Analysen zu hypothetischen Stoerfaellen; a) Hypothetische Lufteinbrueche; b) Belastung der Brennstoffpartikel bei schnellen Transienten. Die Problemstellung der einzelnen Aufgabenpakete werden erlaeutert und die erzielten wesentlichen Ergebnisse dargestellt. Die 8 Themenkomplexe sind einzeln in der Datenb...
Nuclear Engineering and Design, 2006
Nuclear Engineering and Design
The institute of nuclear engineering and energy systems (IKE), University of Stuttgart, Germany h... more The institute of nuclear engineering and energy systems (IKE), University of Stuttgart, Germany has developed a new thermal hydraulic tool which can be used for three-dimensional thermal hydraulic analysis of pebble bed as well as block type HTRs. During nominal operation, the flow inside the gas-cooled High Temperature Reactor is essentially INTRODUCTION Considering some criterion like optimal use of natural resources, proliferation resistance, nuclear safety excellence, cost saving, satisfying broader requirements (hydrogen production, desalination) etc, six systems are selected by the Generation IV International Forum as 4th generation nuclear system and two of the chosen six systems are gas cooled system [1]. The high temperature gas cooled reactor is considered as one of the most promising generation IV reactors due to its inherent safety performance as well as its high conversion efficiency due to higher outlet coolant temperature. For the assessment of the feasibility and saf...
Presentation des proprietes intrinseques de securite du reacteur a lit de boulets modulaire devel... more Presentation des proprietes intrinseques de securite du reacteur a lit de boulets modulaire developpe en Allemagne Federale
Transactions of the American Nuclear Society, 1979
... Publication Date, 1979 Jan 01. OSTI Identifier, OSTI ID: 6810626. Report Number(s), CONF-7905... more ... Publication Date, 1979 Jan 01. OSTI Identifier, OSTI ID: 6810626. Report Number(s), CONF-790519-. Other Number(s), Journal ID: CODEN: TANSA. Resource Type, Conference. Specific Type, Journal Article. Resource Relation, Journal ...
The temperature dependent, ideal gas scattering kernel for heavy nuclei with pronounced resonance... more The temperature dependent, ideal gas scattering kernel for heavy nuclei with pronounced resonances was developed, proved and implemented in the data processing code NJOY from which the scattering probability tables were prepared. Those tables were introduced to the well known MCNP code. The analytic solution of this scattering kernel is consistent with the Doppler Broadening method of D. E. Cullen and C. R. Weisbin. In this study we present an alternative stochastic algorithm based on MCNP subroutines which allows for Doppler broadening of the integral as well as double differential cross section. The analytical solution of the kernel is confirmed. This stochastic method is then introduced into the MCNP code by means of a rejection method, suggested originally by W. Rothenstein. The differences between the new kernel and the standard MCNP kernel are illustrated for specific resonances of U238, Th232, Au197 and Hg199. LWR unit cell calculations are performed and criticality, reaction...
Abstract The ingress of large amounts of water into the primary circuit of an HTR-Module represen... more Abstract The ingress of large amounts of water into the primary circuit of an HTR-Module represents the most severe hazard potential of that reactor plant. Nevertheless, the consequences of these accidents are shown to be practically negligible for the design basis accident and are still tolerable even for extreme hypothetical postulates. This benign behavior of the HTR-Module is due to many inherent properties which are especially designed into the nuclear steam supply system and will be explained in the paper. The core response due to the ingress of neutron moderating steam is discussed in detail and the consequences of the production of inflammable water gas by the chemical reaction of graphite and steam are shown. Concerning the environmental radiation hazard of the worst, still plausible hypothetical accident it is claimed that the radiation dose will not exceed the natural radiation dose accumulated over 50 years by more than an order of magnitude.
Nuclear Engineering and Design, 1988
To retain fission products after postulated accidents, power reactors usually rely on active safe... more To retain fission products after postulated accidents, power reactors usually rely on active safety systems inside the primary circuit, such as e.g. redundant shut down systems and multiple redundant decay heat removal systems. The HTR-Module is employing a different approach which relies entirely on the ability of the coated particle to retain all key radio-nuclides as long as a certain maximum fuel element temperature is not exceeded. Consequently, the reactor is designed such that for any postulated accident this maximum fuel element temperature is not reached even without relying on any active safety systems inside the primary circuit, since the decay heat can be removed to an outside heat sink solely by passive means. The paper discusses the experimental results of fission product release from spherical fuel elements for various temperatures. From the tests as well as from statistical considerations it can be concluded that any hazardous radiation dose to the environment can be excluded if the maximum fuel element temperature in the HTR-Module stays below 1600°C.
Nuclear Engineering and Design, 1990