Corrigendum to "Proton exchange membrane electrolytic enrichment system and tritium residual ratio curve method for analysis of tritium concentration in seawater" [Anal. Chim. Acta 1383 (2026) 344898

Proton exchange membrane electrolytic enrichment system and tritium residual ratio curve method for analysis of tritium concentration in seawater.

The Tokai Reprocessing Plant has reprocessed the total amount of 1,140 tons of spent fuels since 1977 to the end of fiscal year 2008.During the operation, radioactive liquid effluent has been discharged into the sea from the outlet of the pipeline after the discharge approval.The amount of 3 H discharged to the sea was 4.5 PBq in total.Therefore, since 1978, JAEA has sampled seawater around the outlet every month.Tritium concentrations in seawater were analyzed and measured using a liquid scintillation counter.All data were used to calculate the dilution factor which means the ratio of the 3 H concentration in seawater to that in liquid effluent.The number of 3 H samples with concentrations below the detection limit was 9,079 (82.0 %) and the number of those from the limit to 40 Bq/L (as quantification limit) was 1,964 (17.7 %).The maximum concentration was 1,700 Bq/L at the point just above the outlet in 1979.Moreover, the dilution factors were ranged between 240 and 6,500,000.All 3 H concentrations in water were confirmed to be below 60,000 Bq/L that was specified by the law and there has been no concern about environmental safety risk.

A new nuclear fuel reprocessing plant in Aomori prefecture, Japan, began its reprocessing testing in March of 2006. During testing, tritium-contaminated wastewater was intermittently released into the coastal sea and diluted by the surrounding seawater. We measured tritium concentrations in seawater along the Pacific coast in the Aomori area to understand its temporal and geographical variation.Coastal seawater samples were collected two or three times a year at four sites along the coast from 2006 to 2009. Samples were enriched by electrolysis up to a volume reduction factor of fifteen. Both tritium and deuterium concentrations were measured to calculate the samples’ tritium concentrations.Tritium concentrations obtained in this way were usually below 0.5 Bq/L, but they sometimes exceeded 1.0 Bq/L at the four sites on separate dates. From this result we estimate that the tritium-contaminated water is diluted by the coastal water current or by the stagnating water in the release area while it is discharged.

The Tokai Reprocessing Plant has reprocessed the total amount of 1,140 tons of spent fuels since 1977 to the end of fiscal year 2008. During the operation, radioactive liquid effluent has been discharged into the sea from the outlet of the pipeline after the discharge approval. The amount of 3 H discharged to the sea was 4.5 PBq in total. Therefore, since 1978, JAEA has sampled seawater around the outlet every month. Tritium concentrations in seawater were analyzed and measured using a liquid scintillation counter. All data were used to calculate the dilution factor which means the ratio of the 3 H concentration in seawater to that in liquid effluent. The number of 3 H samples with concentrations below the detection limit was 9,079 (82.0 %) and the number of those from the limit to 40 Bq/L (as quantification limit) was 1,964 (17.7 %). The maximum concentration was 1,700 Bq/L at the point just above the outlet in 1979. Moreover, the dilution factors were ranged between 240 and 6,500,000. All 3 H concentrations in water were confirmed to be below 60,000 Bq/L that was specified by the law and there has been no concern about environmental safety risk.

Dissolved orthophosphate (phosphate) is one of the major nutrient elements in natural waters (lakes, rivers, oceans) easily uptaken by primary producers. Monitoring its concentration in seawater will allow to better understand the biogeochemical cycles and the ocean role in climate evolution. Phosphate is an electroinactive specie that is previously complexed in situ at acidic pH with molybdates. In order to avoid silicate interference a ratio protons over molybdates equal to 70 is required. The reagents are formed in situ by oxidation of 2 different molybdenum electrodes. The first oxidation allows to form H+ that cross a proton exchange membrane to obtain the pH conditions needed in the complexation cell. Then, the second molybdenum electrode is oxidized to reach the ratio (H+/MoO4 2-) = 70 and form the phosphomolybdic complex. The counter electrode is isolated behind a Nafion® membrane to limit the reduction of H+ into H2. Because phosphate concentration in seawater is quite low, i.e. few nanomolar in the surface ocean, up to 5 µmol.L-1 at deepest waters, electrochemical detection method requires high sensitivity. Therefore, cyclic voltammetry cannot be used neither chronoamperometry as a rotating electrode is needed to control the convection and it is not suitable for an in situintegrated sensor. Square Wave Voltammetry (SVW) is proposed to detect phosphomolybdic complex in seawater as it offers an optimal combination of potential modulation (potential ramp combined with short term potential pulses) and a specific current sampling reducing the effect of capacitive current. The mechanism of reduction of phosphomolybdic complex is still not fully elucidated. Depending on the pH and the phosphate concentration, different types of complex are formed, and polymer structures have also been observed [1]. Therefore, the reduction of Mo(VI) into a mix of Mo(V)/Mo(IV) observed on the square wave voltammograms showed different behaviours depending on experimental conditions. Indeed, at 250 Hz frequency, a saturation of the signal is quickly observed when the phosphate concentration increased (> 1 µmol.L-1) compared to 2.5 Hz frequency that allowing to obtain a linear behaviour on the whole concentration range (0-6 µmol.L-1) [2]. All the experimental parameters such as molybdenum oxidation charges, time of complexation and SWV parameters, have been optimized using a laboratory prototype in order to detect the smallest phosphate concentration possible, as fast as possible. Those parameters are currently on adaptation for the in situ version of the sensor as the design of the electrochemical cells has a strong influence on the diffusion time (homogenisation of the solution) and so on the detection signal. The electronics of the sensor is also in development and a comparison of its performance compared with the commercial Metrohm® potentiostat will be presented. The in situsensor will then be deployed in the ocean for inter-comparison tests. [1] Jonca et al.,Int. J. Electrochem. Sci. 7 (2012) 7325-7348 [2] Barus/Romanytsia et al., Talanta 160 (2016) 417-424

Establishing the tritium level along the Romanian Black Sea Coast, after 10 years of exploitation of the nuclear power plant from Cernavoda, is a first step in evaluating its impact on the Black Sea ecosystem. The monitoring program consists of tritium activity concentration measurement in sea water and precipitation from Black Sea Coast between April 2005 and April 2006. The sampling points were spread over the Danube-Black Sea Canal - before the locks Agigea and Navodari, and Black Sea along the coast to the Bulgarian border. The average tritium concentration in sea water collected from the sampling locations had the value of 11.1 +/- 2.1 TU, close to tritium concentration in precipitation. Although an operating nuclear power plant exists in the monitored area, the values of tritium concentration in two locations are slightly higher than those recorded elsewhere. To conclude, it could be emphasized that until now, Cernavoda NPP did not had any influence on the tritium concentration of the Black Sea Shore.

An off-line automated preconcentration system with ethylenediaminetriacetate chelating resin for the determination of trace metals in seawater by high-resolution inductively coupled plasma mass spectrometry

Following the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011, large quantities of radioactive materials were released into the atmosphere and ocean. Since the FDNPP nuclear accident, Tokyo Electric Power Company (TEPCO) operators have been implementing measures to reduce groundwater inflow into the FDNPP damaged reactor buildings while pumping water to cool the nuclear reactors and fuel debris. The resulting huge water volume began the discharge into the ocean from August 2023, after being treated by an Advanced Liquid Processing System (ALPS) to remove radionuclides for acceptable discharge levels except tritium. Since then, tritium concentrations in seawater and aquatic ecosystems near the FDNPP site are continuously monitored and disseminated publicly. It is essential to assess the long-term safety threshold of ALPS-treated water discharge procedure in terms of tritium concentration in coastal areas of Japan and the Pacific Ocean. However, there is no global oceanic simulation with tritium concentration and, by extension, no projection of tritium concentration at Pacific Ocean scale.In this study, we used the TEPCO ALPS treated water release plan as an input to the ocean general circulation model (OGCM) COCO4.9, which is the ocean component of the Model for Interdisciplinary Research on Climate, version 6 (MIROC6 [1]). This approach allowed us to simulate the anthropogenic tritium concentration in the ocean due to ALPS treated water release in the forthcoming decades. The spatial distribution and temporal evolution of the projected tritium concentrations in different parts of the Pacific Ocean, as well as the impact of global warming on them, were analyzed. Moreover, the anthropogenic tritium concentration following the FDNPP accident was modeled to evaluate how large the tritium concentrations due to current treated water release are compared to the accidental one in 2011. Finally, given that oceanic tritium concentrations are mainly controlled by ocean mixing, our study represents a valuable opportunity to evaluate the impact of the Kuroshio current representation in COCO4.9 on tritium concentrations at non-eddy-resolving and eddy-resolving horizontal resolutions.[1] Tatebe et al., Geosci. Model Dev., 12, 2727–2765, doi:10.5194/gmd-12-2727-2019, 2019.

Power controller design for electrolysis systems with DC/DC interface supporting fast dynamic operation: A model-based and experimental study

The implementation of electrolysis systems for hydrogen production has continued to grow as the paradigm shift towards renewable energy and fuels progresses. However, when intermittent renewable energy sources power conventional polymer electrolyte membrane (PEM) electrolysis systems, the performance and safety of PEM electrolyzers degrade due to gas crossover. In order to make electrochemical hydrogen production safer when using intermittent renewable energy, decoupled electrolysis systems have been introduced to temporally and spatially separate the evolution of hydrogen and oxygen. This makes the electrolysis system safer, but it sacrifices efficiency compared to conventional electrolysis systems. In this presentation, I will discuss a cerium-mediated decoupled electrolysis system that can both produce hydrogen and store energy in the redox couple. Cerium was chosen due to its large redox potential of 1.6V, which is higher than water oxidation. This means that in one cell (charging cell), an energy input allows cerium to be oxidized while hydrogen is reduced, and in the other cell (discharging cell), energy can be generated by reducing cerium and oxidizing water. By combining experimental results and grid modeling, we identify optimal grid-integration strategies for the decoupled electrolysis system and provide guidelines for its dynamic operation with variable renewable electricity sources. Furthermore, since the oxidation of cerium and water are competing in the charging cell, Faradaic efficiency (FE) for the cerium reaction is less than 100%, which limits total efficiency of the system. To improve the FE of cerium oxidation, dynamic potential pulsing was employed to maintain a high concentration of cerium at the electrode surface improving the FE. The four variables that affect the behavior of the pulses include the oxidation pulse voltage, the rest voltage, the oxidation pulse duration, and the rest duration. Since the effect of these four factors on the FE and cerium conversion rate were unknown, we employed a Bayesian optimization (BO) to approach to identify the optimum combination of the four variables. The BO method was combined with electrochemical models of the reaction to accelerate the search. Finally, the optimal results will be put into context in terms of their effect on the performance and feasibility of the proposed cerium-mediated decoupled water electrolysis and energy storage system. Figure 1

The low level tritium, released to marine environment from nuclear facilities, incorporated by marine matrices as tissue free water tritium (TFWT) and organically bound tritium (OBT), was studies for 3 years at Tarapur, situated on the west coast of India. Results show that the tritium concentration in sea water was correlated with TFWT concentration in sea weeds, sediment and marine animals as, with correlation coefficients of 0.6, 0.8 and 0.96 respectively. The TFWT to OBT ratios were observed to be 5.7, 4.9 and 3.6 respectively in seaweed, sediment and marine animals.

The Department of Energy (DOE) has identified hydrogen production by electrolysis of water at forecourt stations as a critical technology for transition to the hydrogen economy; however, the cost of hydrogen produced by present commercially available electrolysis systems is considerably higher than the DOE 2015 and 2020 cost targets. Analyses of proton-exchange membrane (PEM) electrolyzer systems indicate that reductions in electricity consumption and electrolyzer stack and system capital cost are required to meet the DOE cost targets. The primary objective is to develop and demonstrate a cost-effective energy-based system for electrolytic generation of hydrogen. The goal is to increase PEM electrolyzer efficiency and to reduce electrolyzer stack and system capital cost to meet the DOE cost targets for distributed electrolysis. To accomplish this objective, work was conducted by a team consisting of Giner, Inc. (Giner), Virginia Polytechnic Institute & University (VT), and domnick hunter group, a subsidiary of Parker Hannifin (Parker). The project focused on four (4) key areas: (1) development of a high-efficiency, high-strength membrane; (2) development of a long-life cell-separator; (3) scale-up of cell active area to 290 cm2 (from 160 cm²); and (4) development of a prototype commercial electrolyzer system. In each of the key stack development areas Giner and our team members conducted focused development in laboratory-scale hardware, with analytical support as necessary, followed by life-testing of the most promising candidate materials. Selected components were then scaled up and incorporated into low-cost scaled-up stack hardware. The project culminated in the fabrication and testing of a highly efficient electrolyzer system for production of 0.5 kg/hr hydrogen and validation of the stack and system in testing at the National Renewable Energy Laboratory (NREL).

An instrument was developed for the measurement of gaseous ammonia concentration, NH(3(sw,eq)), in equilibrium with surface waters, notably ocean water. The instrument measures the ammonia flux from a flowing water surface under defined conditions and allows the calculation of NH(3(sw,eq)) from the principles of Fickian diffusion. The flux collector resembles a wetted parallel plate denuder previously developed for air sampling. The sample under study runs on one plate of the device; the ammonia released from the sample is collected by a slow flow of a receptor liquid on the other plate. The NH(3) + NH(4)(+) (hereinafter called N(T)) in the effluent receptor liquid is preconcentrated on a silica gel column and subsequently measured by a fluorometric flow injection analysis (FIA) system. With a 6-min cycle (4-min load, 2-min inject), the analytical system can measure down to 0.3 nM N(T) in the receptor liquid. Coupled with the flux collector, it is sufficiently sensitive to measure the ammonia flux from seawater. The instrument design is such that it is little affected by ambient ammonia. In both laboratory (N(T) 0.2-50 μM), and field investigations (N(T) 0.18-1.7 μM) good linearity between the ammonia flux and the N(T) concentration in seawater (spiked, synthetic, natural) was observed, although aged seawater, with depleted N(T) content, behaves in an unusual fashion upon N(T) addition, showing the existence of an "ammonia demand". NH(3(sw,eq)) levels from ocean water measured in the Coconut Island Laboratory, HI, ranged from 6.6 to 33 nmol/m(3) with an average of 17.4 ± 6.9 nmol/m(3), in comparison to 2.8-21 nmol/m(3) (average 10 ± 7 nmol/m(3)) NH(3(sw,eq)) values previously reported for the Central Pacific Ocean (Quinn, P. K.; et al. J. Geophys. Res. 1990, 95, 16405-16416).

Measured concentrations of Cs-137, tritium, Tc-99, Pu-239+240 and Am-241 in representative materials from the Irish Sea were investigated with reference to continuing remobilisation from sediments. Long time series of monitoring data since the 1960s were employed. Cs-137 in sea water and fish shows peaks in concentrations normalised to discharge rate (NACs) from 1985 to 1989. This is consistent with the time needed for dispersion in sea water following the preceding reductions in discharges; continuing enhancements of NACs above pre-1970s levels follow, consistent with the effect of activity remobilised from sediment. It is estimated that about 300 TBq of Cs-137 was remobilised from the immediate tidal area around Sellafield from 1989 to 2009. The enhancements in concentrations continue to this day, with the effect of remobilisation at present being ∼6 TBq y−1, approximately doubling the effect of direct discharges. To provide an indication for the future, the rate of Cs-137 remobilisation is decreasing with a half-time of ∼6 years. The data for tritium and Tc-99 were examined in view of the interest in these radionuclides. The concentrations broadly reflect the levels of discharges and the need for dispersion. As expected, there is no evidence of sustained remobilisation of tritium, due to its mobility (or low Kd). The same lack of evidence was found to apply for Tc-99 despite known sorption of a small proportion of the discharged activity by Irish Sea sediments. Pu-239+240, by contrast, shows much evidence of the effect of remobilisation; concentrations in sea water near Sellafield have reduced much more slowly than discharges. At Southerness, ∼50 km away, there was no significant reduction in sea water concentrations from 1985 to 1996, and winkles showed an increase then decrease in concentrations over this period, consistent with a spreading of activity. This effect was replicated in mud at Garlieston, ∼70 km from Sellafield. For Am-241, the rate of grow-in from Pu-241 has dominated direct discharges since the late 1970s. Grow-in continues today in the Irish Sea at the rate of ∼8 TBq y−1, ∼200 times the rate of direct discharge. Winkles at Southerness show evidence of a spreading effect of Am-241, with an increase then decrease from 1985 to 1996. At Garlieston there was an increase in concentrations in mud from 1985 to 1997, and at Carlingford in Northern Ireland the concentration of Am-241 in mud appears to be increasing still. This effect of the spread of activity away from Sellafield may continue, at least in the near future.

One way to control lateral buckling in the operation phase for High Pressure High Temperature (HPHT) pipelines is by deliberately introducing residual curvature sections at intervals along the pipeline by adjusting the straightener settings of the pipelay tower, as described in a patent held by Statoil [1]. This method has been applied with reel-lay installation for a number of shallow water pipelines in Europe (Statoil’s Skuld project and Total’s Edradour project). The paper presents the benefits as well as the feasibility of the use of Residual Curvature Method (RCM) to control lateral buckling for deep water applications which involves high top tension in the overbend and high pressure and twist of the RC section in the sagbend. The study cases consider the application of the method for pipelines in 1850m water depth which are pushing the pipe top tension close to the limit of the capacity of the tensioners of Heerema Marine Contractor’s (HMC) Reel-lay vessel the Aegir. There are some challenges of the application of the residual curve method for deep water pipelines. Due to high top tension, some potential issues are investigated during lowering of the curved section from the straightener, passing the tensioners and through the J-lay tower into the water to the seabed. Detailed analyses have been performed to check the interaction of the residual curved pipe section against the tensioners (the effect of the squeeze load on the RC section) and to assess the maximum bending moment generated when the residual curved section is under high top tension below the tensioners against the Load Controlled Condition (LCC) for local buckling bending moment limit. Another consideration is the increase of hydrostatic pressure in deep water which could limit the allowable bending moment in the sagbend when lowering the curved sections to the seabed. Discussions are presented to the feasibility of the concept including the proposed ways of mitigation for the aforementioned potential issues. The paper will also show an improved prediction of pipe twist/roll by comparing a published analytical 2D plane solution against the 3D FEA model prediction. The improved prediction, which considers the out of plane bending component of the pipe catenary, results in an increase of pipe twist in the sagbend section. This reduces the bending moment in the residual curved section when entering the sagbend and increases the probability to roll the curved section over to the horizontal plane on the seabed.