Characterization of contamination: french analysis of international EMECC campaigns

International audienceThe reduction in collective dose is an important objective for all nuclear plant operators. One of the ways for studying the impact of design and operation parameters is the measurement campaigns of contamination in PWRs. EDF' strategy is based on several levels of measurement: local dose rates give raw information; dose rate index and CZT spectrometry allow an evaluation of the radiological situation of each plant, its evolution and comparison with other plants. For very accurate characterization, EDF performs gamma spectrometry measurements with CEA and its EMECC system, with more than 300 campaigns in EDF plants and also about 70 campaigns in collaboration with other operators. Recent collaboration between EDF and other operators with excellent collective dosimetry resulted in measurements during several Refuelling Outages. The present paper presents results obtained with EDF Energy at Sizewell B Outage 8, ELECTRABEL at Doel 3 Outage 25 and Doel 4 Outage 22 and CNAT at Trillo Outage 21. The paper presents the results in terms of deposited activities and dose rates in RCS and CVCS, and compares them with French PWRs, and especially with Saint-Laurent B1. The specificities of all these plants are identified, to explain the differences in results, either for dose rates, deposited activities or collective dosimetry. All these comparisons will enable EDF and collaborative operators to improve the performance of their own plants

Auxiliary system contamination in French PWRs

International audienceIn order to study the impact of design and operating parameters on French PWR contamination, the CEA, by request of EDF, has been performing in-situ gamma spectrometry measurements using the so-called EMECC device for 37 years. These measurements have allowed researchers to characterize contamination levels accurately (surface activities by radionuclide), mainly in primary systems, but also in some reactor auxiliary systems such as the Chemical and Volume Control System (CVCS), the Residual Heat Removal System (RHRS), the Nuclear Sampling System (NSS) or the Fuel Pool Cooling and Cleanup System (FPCS). Based on EMECC campaigns performed in different standardized plant series, this paper shows that the contamination of nuclear auxiliary systems presents differences in comparison to the contamination of the primary system:-The Co-58 and Co-60 deposited activities on the CVCS, RHRS, NSS and FPCS are generally lower. On the other hand, the Ag-110m contamination is higher with a considerable recontamination resulting during cold shutdowns.-The dose rates around the auxiliary systems are generally higher.-The Co-58 contribution and especially the Ag-110m contribution are both higher. For auxiliary systems that do not operate for several months, the Co-60 contribution emerges as the major one.-The nuclear auxiliary systems are the only circuits that allow us to measure the Cr-51 surface activities.These characteristics are due to different design and operating conditions, particularly the following : the presence of heat exchangers and lower fluid temperature, different flow rates, thinner thickness of pipes and of exchanger shells, the presence of filtering systems and operations during a short period. A final observation is that, the peculiar behavior of Ag-110m inside the NSS generally results in a poor estimation of the Ag-110m volume activity in the primary coolant

EDF strategy for the primary coolant pH

International audienceEDF has experienced different boron-Lithium coordination curves into the primary coolant of nuclear power plants. The applied chemistries have led to the target pH of 7.0 and 7.2 at 300°C for the middle of the fuel cycles. But different strategies have been tested for the beginning and the end of cycle giving a larger range of pH. Since the load following implementation for EDF plants, it is difficult to keep a constant pH and it is more reasonable to consider that it moves around the target value. This paper also draws the influence of the pH evolution on the primary-secondary leaks for the oldest plants with 600 MA steam generator tubes. Actually, the demonstrated effect of the primary coolant effect on crack oxide solubility explains the level of the weak and stabilised leaks. This leads to propose a specific B/Li coordination to mitigate operation difficulties. This analysis may help chemists to choose the suitable pH for different plant families according to the various objectives

Low primary system contamination levels in some French PWRs

International audiencePWRs equipped with Steam Generator tubing in a nickel-based alloy (alloy 600 or 690) are generally characterized by higher Co-58 peaks during cold shutdowns (order of magnitude of 100 GBq/m3) and higher Co-58 deposited activities (several GBq/m²) compared to PWRs equipped with SG tubing in an iron-based alloy (alloy 800 or stainless steel). However, the trends are different for the Steam Generator Replacement (SGR) with alloy 690 carried out in the last decade, in particular for the SAINT-LAURENT-B1 PWR: after an increase in the Co-58 contamination just after the SGR, the contamination on the primary system decreases and reaches a very low level several cycles after the SGR. The Co-58 peak during cold shutdowns follows the same variation, it drops by a factor of 10 to 100. Similar levels are also measured in the last French operating PWR generation (N4). The key factor of these low Co-58 deposited and released activities is the surface finish of alloy 690TT SG tubing by means of an improved manufacturing process. The nickel release is low enough to limit the presence of metallic nickel or nickel oxide, which tend to form deposits on fuel elements. In consequence, nickel deposits on fuel elements and then 58Co volume and surface activities are reduced

Characterization of contamination : EMECC campaign at Sizewell B and comparison with French PWRs

International audienceThe reduction of collective dose is an important objective for all nuclear plant operators. One of the support for studying the impact of design and operation parameters is the measurement campaigns of contamination in PWRs. EDF performs consequently gamma spectrometry measurements with CEA and his EMECC system, with more than 200 campaigns in EDF plants and also about 70 campaigns in collaboration with other operators. A recent collaboration between EDF and British Energy resulted in measurements during Refueling Outage 8 at Sizewell B, a PWR with excellent collective dosimetry. The paper presents the results in term of deposited activities and dose rates in RCS and CVCS, and compares with French PWRs, and especially with Saint-Laurent B1. If the dose rates are very comparable, the collective dosimetry is slightly lower for Sizewell B. First explanations are searched for the established differences. Lower 58 Co activity for Sizewell B is probably due to the good manufacturing of alloy 690 steam generator tubing, higher 60 Co activity is probably linked with the use of alloy 718 grids, not totally removed after 8 cycles. The origin of difference in collective dosimetry should be less time spent in dosing outage operations, even if the total time spent in controlled area is rather higher in Sizewell B. An accurate comparison for specific chosen outage operations is in progress. Another explanation should be differences in contamination on auxiliary systems, or differences in volume activities. To explore further these hypothesis, complementary measurements are planned by BE and EDF. All these comparisons will give new elements to BE and EDF to improve the behaviour of their own plants

Status of primary system Contamination in French PWRs

International audienceThe reduction of collective dose is an important objective for all nuclear plant operators. Since the beginning of French PWR commissioning, the French strategy has been to study the impact of design and operating parameters. With the codes and the test loops, the third support to these studies is the measurement campaigns of contamination in PWRs.Since 1971, the deposited activities in PWR primary systems have been measured by gamma spectrometry, deposited activities providing more information than dose rates. These gamma spectrometry measurements with the EMECC system represent about 250 measurement campaigns in France and abroad. This paper presents the status of primary system contamination in French PWRs and some of the main lessons learnt from the EMECC campaign analyses.The primary system 60Co contamination in French PWRs has a tendency to increase for several cycles and then to be constant or even to decrease, whereas 58Co contamination tends to decrease on primary coolant piping and to slightly increase on SG tubing. Thanks to the improvements of French PWR design and operation (pH300°C of 7.2, Zry spacer grids, 690TT Steam generator tubing with a low cobalt content…), the dose rate indices tend to decrease with PWR generations and operating cycles

Complete analyse of zinc injection impact at BUGEY 2&4

International audienceZinc injection at BUGEY 2 and 4 provides a distinctive experience in the world, which can be used for a better understanding of the role of the zinc in the primary coolant and its impact on the radiation fields, fuel and wastes. BUGEY Unit 2 and Unit 4 are two EDF 900 MWe PWRs. The alloy 600 MA Steam Generators of BUGEY 4 have been replaced by alloy 690 TT SGs at the end of cycle 23. EDF implemented the Zinc injection for the first time in France at BUGEY 2 Cycle 22 four years ago in order to reduce the dose rates. In 2005, the zinc injection was also initiated at BUGEY 4 Cycle 23, during the previous cycle of the steam generator replacement. The gamma-spectrometry measurements performed at BUGEY on the steam generator tubing and primary pipes for several cycles (before and after the zinc injection) seem to show that the zinc incorporation on the oxide layers is not immediate or uniform in the different portions of the circuits and the dose rate reduction may be influenced by different factors. The interest of BUGEY feedback is the fact that unlike other units in the world, the zinc injection is the only chemistry modification introduced in the primary coolant: other actions supposed to have a positive effect on radiation fields (pH, lithium concentration increase, fuel cleaning) have not been applied. Thereby the actual benefit due the zinc injection can be evaluated for the units similar to those of BUGEY (with alloy 600 and 690). This paper gives an overview of the experience gathered at BUGEY during the first cycles of zinc injection and presents the future EDF strategy concerning zinc injection

The impact of steam generator replacement on PWR primary system contamination

International audienceThis paper analyses the impact of Steam Generator Replacement (SGR) on PWR primary circuit contamination. It presents a comparison of the activities deposited inside the primary system and released during refuelling outages after SGR with three different SG tube alloys (600, 690 and 800) and different SG tube manufacturing processes. A SGR has a great impact on the primary system contamination. After SGR, whatever the SG tube material is, the typical variations are the following: • The Co-58 contamination increases for 1 to 3 cycles, and then decreases to very low levels in some cases, mainly depending on the manufacturing process of the replacement SG tubes. • The Co-60 contamination tends to decrease on the primary coolant pipes and increases by a lower rate on the new SG tubes. This analysis highlights the importance on contamination levels after SGR of both the corrosion product deposits on the primary surfaces before SGR and the surface finish of the SG tubes related to their manufacturing process

Patrimoine culturel immatériel. Traitement documentaire des archives sonores inédites. Guide des bonnes pratiques.

Guide de bonne pratique pour l'analyse des documents sonores inédits.La " galaxie Gutenberg " ne dit pas tout... l'oralité marque aussi très largement nos sociétés occidentales. Les archives orales doivent pouvoir être repérées, analysées et comparées aux autres documents comme l''image et l'écrit. Pour cela, il est nécessaire de proposer un outil permettant l'analyse des phonogrammes inédits. Déjà, en 1994, la FAMDT avait fait paraître un manuel pour la mise en place de banques de données des documents sonores inédits. Aujourd'hui, ce guide est réédité en collaboration avec l'Association Française de détenteurs de documents audiovisuels et sonores (AFAS) enrichi de l'expérience des phonothèques. Publié en 1997 puis en 2001, la réédition de ce manuel a toujours pour objectif de proposer un outil pratique qui respecte la spécificité de la source orale tout en suivant les conventions des règles et des formats utilisés dans les centres de ressources. De nombreuses annexes et des exemples concrets permettent de prendre en compte le traitement de l'archive sonore inédite dans une banque de données documentaires, incluant les problèmes spécifiques liés aux enregistrements concernant la littérature orale et les musiques traditionnelles