- Email: [email protected]
01890 Risk-informed inservice inspection program
06 Electrical power generation and utilization (scientific, technical)
recycled safely and efficiently in a large fusion device. At the start DTEl 20 g of tritium were available on the JET site. About 100 g of tritium were supplied from the AGHS to the users, which necessitated the recycling of tritium at least five times. Approximately 220 tritium plasma shots were performed during DTEI. Large amounts of tritium were temporarily trapped in the torus. This overview presents the performance of the whole AGHS during DTEl as well as general aspects such as the preparation for DTEI; the quantities of gases supplied from the AGHS to the users and pumped back to the AGHS; tritium accountancy; interlock systems; failure of equipment; and gives detailed information of the gas processing in each subsystem of the AGHS. As a result of the performance of the AGHS during DTEI it can be confidently stated that the AGHS is ready for further deuterium-tritium experiments.
The properties of WWER-440 type reactor pressure vessel steels cut out from operated units
OOlO1885
Korolev. Y. Nrrcl. Errg. Des.. 2000. 195, (2). 137-142. This paper presents the results of a study on radiation degradation occurring in WWER-440 reactor pressure vessel (RPV) steel, using subsize impact specimens (5 x 5 x 27.5 mm’). The results of testing trepans and templates cut out from WWER-440 reactor pressure vessels are considered. Ductile-to-brittle transition temperatures (DB’IT) obtained using standard Charpy and subsize impact specimens are compared. The relation between these two values is established.
00/01888
The safety case of JET D-T operation
Bell, A. C. Fil.rion Dig. rnrcl DP.Y@. 1999. 47. I 15-l 30. Formal approval was required to permit tritium operation of the JET machine to proceed and a safety case was prepared in order to justify this. The standards and the methodology used are summarised both for the active gas handling system and for the torus systems. The main design safety principles are described and accident sequences are reviewed. Both deterministic and probabilistic analysis was carried out and the main results in terms of source terms, on-site and off-site doses are presented. It is shown that operation of JET with deuterium-tritium plasmas complies with the ALARP principle. 00/01887 Tritium retention and clean-up in JET Andrew. P. Fritsi*>r~EII,~. crrr(/ Dc.v@. 1999. 47. 233-245. During I997 JET operation with D-T plasmas. 35 g of tritium were introduced into the tours, mainly by gas puffing. It was found that during this period, the tours tritium inventory would accumulate at a rate of about 40% of the input. After tritium operation ceased, the experimental programme continued with deuteriumand hydrogen-fuelled experiments, during which time the tritium inventory decreased to about 17% of the total input. Techniques aimed at detritiation of the torus included methods using deuterium gas (such as deuterium pulsing) which were used in the middle of the experimental campaign, and methods which could adversely affect the torus vacuum conditions (such as air purges) which were reserved for the period after the experimental campaign. Whilst it was found that the plasma tritium fraction could be reduced to below the I% level in a few days, the tritium inventory reached a virtually steady level of about 6 g by the end of the campaign.
Economics, policy, supply, forecasts 00/01888
Analysis of l-129 in radwastes by neutron activation
Chao, J. H. Appl. Ror/it//. f.vor.. 1999. 51. (2). 137-143. From the standpoint of radiation health and environmental concern, it ,2ays of low-level waste. The become important to detect “‘1 activity 1 generated from power plants could be released into the environment through the subsequent fuel reprocessing and waste disposal. To minimize radionuclides in this impact. the concentrations of ‘?‘I and some affiliated the wastes to be disposed of should be detected and put in compliance with the stipulated regulations. The process employed to detect ““Ii “I and ““I in radwastes is neutron activation analysis. The long-lived ‘2hI, activated from “‘I, is selected to replace ‘z”1 as an indicator of stable iodine. Longterm neutron irradation and y-ray counting are permitted and the related detection limit can be improved. The proposed method has related advantages of low-counting interferences and convenience for chemical operation over traditional methods; these make it a practical alternative for analysing ““I in radwastes.
00/01889 Economic and safety pressures on nuclear power: a comparison of Russia and Ukraine since the break-up of the Soviet Union Thomas, S. Em~r,e,~Politic. 1999. 27. (I 3). 745-767. Since the Chernobyl accident and the break up of the’doviet Union, nuclear power in Russia and Ukraine has come under intense scrutiny. The West has pursued a policy that the plants should undergo safety upgrades or be closed. However, the resources needed to achieve this have not been available. This paper examines how these pressures have affected nuclear power plants in Ukraine and Russia since 1991. Economic recession and the fall in electricity demand have led to lack of resources for fuel purchase, maintenance and upgrading. The only ‘unsafe’ plant that has been closed is
212
Fuel and Energy Abstracts
July 2000
one at Chernobyl in Ukraine. Russia is life-extending its ‘unsafe’ plants for a further ten years service. In Russia, other plants are dispatched ahead of nuclear plants and in summer, nuclear plants are operated at reduced power. Ukraine’s position as a fossil fuel importer means that there is a greater incentive to run the nuclear plants intensively. This pressure was particularly strong in I992 and 1997. Performance in the years following was much poorer. Ukraine faced an additional challenge in building up an independent regulatory capability from scratch after the break-up of the Soviet Union. While the new body is regarded as technically competent, it may lack the political power to impose its will.
00101890 Risk-informed inservice inspection program Mayfield, M. E. Nat/. &rp. DC.\.. 2000. 195. (2). 211 215. The Nuclear Regulatory Commission (NRC) has developed draft guidance for power reactor licenses on acceptable methods for using probabilistic risk assessment (PRA) information and insights in support of plant-specific applications to change the current licensing basis (CLB) for inservice inspection (ISI) of piping. This process is also known as risk-informed inservice inspection programmes (RI-ISI). The risk-informed inservice inspection process for operating nuclear power plants provides an alternative method for selecting and categorizing piping components that are inspected for the purposes of meeting the requirements of ASME Section XI. A RI-IS1 approach will incorporate probabilistic techniques to help define the scope, type and frequency of inservice inspection. The riskinformed process may support a decrease in the number of inspection and inspection intervals but will also identify areas where increased resources should be allocated to enhance safety. The approach discussed in this paper follows the method developed by NRC staff.
06
ELECTRICAL POWER GENERATION AND UTILIZATION Scientific, technical
00/01891 In situ analysis of electrochemical reactions at a lead surface in sulfuric acid solution Yamaguchi, Y. J. qp Poirer Sourcc.r, 2000. 85. (I), 22-28. An Atomic Force Microscope (AFM) was used to analyse the surface of a lead plate when the reaction corresponding to what occurs at the negative electrode of a lead acid battery, Pb + SOi- * PbS04 + 2e. took place. At the beginning, when the lead plate, on the surface of which lead oxide already existed, was in contact with sulfuric acid, lead sulfate crystals were formed and gradually grew with time without applying any potential. Irr sirrr AFM observation of the formation and the growth of lead sulfate at the notential corresoondinz to the discharge reaction was attemoted. And it was possible along with the reduction of the lead sulfate, which formed in discharging process. The results also showed that the chemically formed lead sulfate crystals were clearly different in appearance from the electrochemically formed ones. These results were also applied to a study of the mechanism of the sulfation process that often occurs in the active material of the negative electrode of a lead acid battery.
00/01892 A comprehensive EMF behind transient reactance (EBTR) model for power system stability study Kabir, S. M. L. Elcc~rric Poirer .Sr.trenr.\. Ru~crrch. 2000. 53. (3). 2 I7 -222. EMF behind transient reactance (EBTR) model of a synchronous generator has widely been used in the studies of power system stability. A single time constant equivalent circuit normally represents the damping in the quadrature axis of a synchronous machine. However, the presence of field in addition to the damper circuit in the direct axis of the machine makes modelling difficult in the direct axis based on the emf behind transient reactance. As a result approximate representations are normally employed. The models based on appropriate representations do not produce accurate results. In this paper. an accurate comprehensive model for the direct axis is presented. The development emerges from the detailed representation of the machine with fluxes as the state variable. The emfs behind field and daxis damper transient reactances are considered in the model. The validity of the model is tested by comparison with the responses obtained from a detailed model.
00/01893
A general load flow method for distribution systems
Haque, M. H. Ekr. Po~cv Sm. Rcs.. 2000. 54. (I ). 47-54. This paper proposes a very simple and efficient method of load flow calculation for a general distribution system having mesh network with more than one feeding node. The distribution system is first converted to an equivalent single source network with radial configuration so that the conventional DisrNow hrwdr cqrrcrriom can be used to solve the load flow problem. The network conversion process creates some break points and
recycled safely and efficiently in a large fusion device. At the start DTEl 20 g of tritium were available on the JET site. About 100 g of tritium were supplied from the AGHS to the users, which necessitated the recycling of tritium at least five times. Approximately 220 tritium plasma shots were performed during DTEI. Large amounts of tritium were temporarily trapped in the torus. This overview presents the performance of the whole AGHS during DTEl as well as general aspects such as the preparation for DTEI; the quantities of gases supplied from the AGHS to the users and pumped back to the AGHS; tritium accountancy; interlock systems; failure of equipment; and gives detailed information of the gas processing in each subsystem of the AGHS. As a result of the performance of the AGHS during DTEI it can be confidently stated that the AGHS is ready for further deuterium-tritium experiments.
The properties of WWER-440 type reactor pressure vessel steels cut out from operated units
OOlO1885
Korolev. Y. Nrrcl. Errg. Des.. 2000. 195, (2). 137-142. This paper presents the results of a study on radiation degradation occurring in WWER-440 reactor pressure vessel (RPV) steel, using subsize impact specimens (5 x 5 x 27.5 mm’). The results of testing trepans and templates cut out from WWER-440 reactor pressure vessels are considered. Ductile-to-brittle transition temperatures (DB’IT) obtained using standard Charpy and subsize impact specimens are compared. The relation between these two values is established.
00/01888
The safety case of JET D-T operation
Bell, A. C. Fil.rion Dig. rnrcl DP.Y@. 1999. 47. I 15-l 30. Formal approval was required to permit tritium operation of the JET machine to proceed and a safety case was prepared in order to justify this. The standards and the methodology used are summarised both for the active gas handling system and for the torus systems. The main design safety principles are described and accident sequences are reviewed. Both deterministic and probabilistic analysis was carried out and the main results in terms of source terms, on-site and off-site doses are presented. It is shown that operation of JET with deuterium-tritium plasmas complies with the ALARP principle. 00/01887 Tritium retention and clean-up in JET Andrew. P. Fritsi*>r~EII,~. crrr(/ Dc.v@. 1999. 47. 233-245. During I997 JET operation with D-T plasmas. 35 g of tritium were introduced into the tours, mainly by gas puffing. It was found that during this period, the tours tritium inventory would accumulate at a rate of about 40% of the input. After tritium operation ceased, the experimental programme continued with deuteriumand hydrogen-fuelled experiments, during which time the tritium inventory decreased to about 17% of the total input. Techniques aimed at detritiation of the torus included methods using deuterium gas (such as deuterium pulsing) which were used in the middle of the experimental campaign, and methods which could adversely affect the torus vacuum conditions (such as air purges) which were reserved for the period after the experimental campaign. Whilst it was found that the plasma tritium fraction could be reduced to below the I% level in a few days, the tritium inventory reached a virtually steady level of about 6 g by the end of the campaign.
Economics, policy, supply, forecasts 00/01888
Analysis of l-129 in radwastes by neutron activation
Chao, J. H. Appl. Ror/it//. f.vor.. 1999. 51. (2). 137-143. From the standpoint of radiation health and environmental concern, it ,2ays of low-level waste. The become important to detect “‘1 activity 1 generated from power plants could be released into the environment through the subsequent fuel reprocessing and waste disposal. To minimize radionuclides in this impact. the concentrations of ‘?‘I and some affiliated the wastes to be disposed of should be detected and put in compliance with the stipulated regulations. The process employed to detect ““Ii “I and ““I in radwastes is neutron activation analysis. The long-lived ‘2hI, activated from “‘I, is selected to replace ‘z”1 as an indicator of stable iodine. Longterm neutron irradation and y-ray counting are permitted and the related detection limit can be improved. The proposed method has related advantages of low-counting interferences and convenience for chemical operation over traditional methods; these make it a practical alternative for analysing ““I in radwastes.
00/01889 Economic and safety pressures on nuclear power: a comparison of Russia and Ukraine since the break-up of the Soviet Union Thomas, S. Em~r,e,~Politic. 1999. 27. (I 3). 745-767. Since the Chernobyl accident and the break up of the’doviet Union, nuclear power in Russia and Ukraine has come under intense scrutiny. The West has pursued a policy that the plants should undergo safety upgrades or be closed. However, the resources needed to achieve this have not been available. This paper examines how these pressures have affected nuclear power plants in Ukraine and Russia since 1991. Economic recession and the fall in electricity demand have led to lack of resources for fuel purchase, maintenance and upgrading. The only ‘unsafe’ plant that has been closed is
212
Fuel and Energy Abstracts
July 2000
one at Chernobyl in Ukraine. Russia is life-extending its ‘unsafe’ plants for a further ten years service. In Russia, other plants are dispatched ahead of nuclear plants and in summer, nuclear plants are operated at reduced power. Ukraine’s position as a fossil fuel importer means that there is a greater incentive to run the nuclear plants intensively. This pressure was particularly strong in I992 and 1997. Performance in the years following was much poorer. Ukraine faced an additional challenge in building up an independent regulatory capability from scratch after the break-up of the Soviet Union. While the new body is regarded as technically competent, it may lack the political power to impose its will.
00101890 Risk-informed inservice inspection program Mayfield, M. E. Nat/. &rp. DC.\.. 2000. 195. (2). 211 215. The Nuclear Regulatory Commission (NRC) has developed draft guidance for power reactor licenses on acceptable methods for using probabilistic risk assessment (PRA) information and insights in support of plant-specific applications to change the current licensing basis (CLB) for inservice inspection (ISI) of piping. This process is also known as risk-informed inservice inspection programmes (RI-ISI). The risk-informed inservice inspection process for operating nuclear power plants provides an alternative method for selecting and categorizing piping components that are inspected for the purposes of meeting the requirements of ASME Section XI. A RI-IS1 approach will incorporate probabilistic techniques to help define the scope, type and frequency of inservice inspection. The riskinformed process may support a decrease in the number of inspection and inspection intervals but will also identify areas where increased resources should be allocated to enhance safety. The approach discussed in this paper follows the method developed by NRC staff.
06
ELECTRICAL POWER GENERATION AND UTILIZATION Scientific, technical
00/01891 In situ analysis of electrochemical reactions at a lead surface in sulfuric acid solution Yamaguchi, Y. J. qp Poirer Sourcc.r, 2000. 85. (I), 22-28. An Atomic Force Microscope (AFM) was used to analyse the surface of a lead plate when the reaction corresponding to what occurs at the negative electrode of a lead acid battery, Pb + SOi- * PbS04 + 2e. took place. At the beginning, when the lead plate, on the surface of which lead oxide already existed, was in contact with sulfuric acid, lead sulfate crystals were formed and gradually grew with time without applying any potential. Irr sirrr AFM observation of the formation and the growth of lead sulfate at the notential corresoondinz to the discharge reaction was attemoted. And it was possible along with the reduction of the lead sulfate, which formed in discharging process. The results also showed that the chemically formed lead sulfate crystals were clearly different in appearance from the electrochemically formed ones. These results were also applied to a study of the mechanism of the sulfation process that often occurs in the active material of the negative electrode of a lead acid battery.
00/01892 A comprehensive EMF behind transient reactance (EBTR) model for power system stability study Kabir, S. M. L. Elcc~rric Poirer .Sr.trenr.\. Ru~crrch. 2000. 53. (3). 2 I7 -222. EMF behind transient reactance (EBTR) model of a synchronous generator has widely been used in the studies of power system stability. A single time constant equivalent circuit normally represents the damping in the quadrature axis of a synchronous machine. However, the presence of field in addition to the damper circuit in the direct axis of the machine makes modelling difficult in the direct axis based on the emf behind transient reactance. As a result approximate representations are normally employed. The models based on appropriate representations do not produce accurate results. In this paper. an accurate comprehensive model for the direct axis is presented. The development emerges from the detailed representation of the machine with fluxes as the state variable. The emfs behind field and daxis damper transient reactances are considered in the model. The validity of the model is tested by comparison with the responses obtained from a detailed model.
00/01893
A general load flow method for distribution systems
Haque, M. H. Ekr. Po~cv Sm. Rcs.. 2000. 54. (I ). 47-54. This paper proposes a very simple and efficient method of load flow calculation for a general distribution system having mesh network with more than one feeding node. The distribution system is first converted to an equivalent single source network with radial configuration so that the conventional DisrNow hrwdr cqrrcrriom can be used to solve the load flow problem. The network conversion process creates some break points and