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

Environmental Tritium is a powerful tracer of groundwater age and it is a key tracer of groundwater movement. Consequently, monitoring of Tritium concentration in groundwater can be a very useful tool for the determination of recent exchanges with surface water and for the presence and the traceability of anthropogenic contributions. Tritium (3H) is a radioactive isotope of hydrogen with a half-life of 12.3 years, which emits low- energy beta particles. It is a naturally occurring radionuclide through the interaction of high-energy cosmic rays with oxygen and nitrogen atoms in the upper atmosphere. The environmental levels of Tritium increased after nuclear weapon tests between 1945 and 1963, and after that it was mainly released from nuclear facilities, especially the heavy water reactor (HWR).However, Tritium concentrations in precipitation have exponentially declined over the past decades as the anthropogenic bomb tritium peak has all but disappeared. At the present, due to the natural decay of tritium and the prohibition of nuclear activities, the activity of tritium in water decreases year by year, and environmental tritium concentrations are close to natural levels of cosmic production. To detect low concentration of tritium in water, a certain degree of enrichment is essential to obtain adequate tritium count rates, through electrolytic system. The principle of electrolytic concentration of tritium is to use the isotope fractionation effect of hydrogen isotopes in the gas and liquid phases. Water samples contain mainly HHO, HDO and some HTO molecules, so by passing an electric current through a conductive water solution, the bonds of the water molecules are broken. Discharge of hydrogen from the cathode is highly isotope-selective for protium, thus, tritium and deuterium are concentrated, leaving most of the tritium in the residual water after reduction of the water sample. One method of 3H electrolytic enrichment was developed and implement in Italy by the ENEA’s Traceability Laboratory (FSN-SICNUC-TNMT – Brasimone research center). The ENEA electrolytic enrichment procedure, which precedes the counting of tritium by liquid scintillation counting (LSC), is performed by an electrolysis system consisting of 20 steel cells, a cooling system, a temperature control unit and three multiple distillation batches for the tritium samples. At present, given the decline in tritium activity in the atmosphere and hydrosphere, low tritium concentrations in groundwater can no longer be neglected, as they can be important indicators of anthropogenic pollutants. A good contribution to the assessment of the vulnerability of aquifers from anthropogenic impact could be offered by the determination of the low tritium in groundwater via the electrolytic enrichment methodology.

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.

New electrolytic enrichment system for tritium determination in water research institute in Bratislava and IT’S first results of tritium activity in precipitation

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

In order to determine the tritium concentration in environmental water samples, the electrolytic enrichment was carried out with (St) and without (S) addition of tritiated water of a certain concentration (deuterium-free) to the samples. With the use of the fundamental formulas on electrolytic enrichment, the deuterium concentration (Dit) before electrolysis for an environmental water sample is determined by liquid scintillation counting and densitometry for the sample St. Furthermore, the tritium concentration in the environmental water sample is determined by the above methods for the sample S, and by the substitution of Dit for Di in the formulas. Tritium concentrations in environmental water samples were found to be determined within an accuracy of 10% by this method when Vi/Vf was 14-25. It is considered that this method dispenses with the direct measurement of low deuterium concentrations (Di) before electrolysis, a special technique on the purification of water for densitometry, and moreover, excludes the possibility of cross contamination in the electrolytic enrichment by the spike cell method.

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.

Tritium monitoring around a nuclear power station in normal operation

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

Assessing the variability of tissue-free water tritium and non-exchangeable organically bound tritium in pine needles in Fukushima using atmospheric titrated water vapor

This prospective life cycle assessment (LCA) compares the environmental impacts of alkaline electrolyser (AE) and proton exchange membrane (PEM) electrolyser systems for green hydrogen production with a special focus on the stack components. The study evaluates both baseline and near-future advanced designs, considering cradle-to-gate life cycle from material production to operation. The electricity source followed by the stacks are identified as major contributors to environmental impacts. No clear winner emerges between AE and PEM in relation to environmental impacts. The advanced designs show a reduced impact in most categories compared to baseline designs which can mainly be attributed to the increased current density. Advanced green hydrogen production technologies outperform grey and blue hydrogen production technologies in all impact categories, except for minerals and metals resource use due to rare earth metals in the stacks. Next to increasing current density, decreasing minimal load requirements. improving sustainable mining practices (including waste treatment) and low carbon intensity steel production routes can enhance the environmental performance of electrolyser systems, aiding the transition to sustainable hydrogen production.

Monitoring of tritium concentration in Hanoi's precipitation from 2011 to 2016

Concentrations of tritium in environmental waters (precipitation, rivers, lakes, tap water) have been determined using electrolytic enrichment and liquid scintillation counting. In waters of big rivers (the Vistula and the Odra rivers), lakes and tap water the annual average concentrations were similar to each other being from 1.4 to 1.9 Bq·dm-3. These concentrations were similar to those in the precipitation in which they ranged from 1.7 to 2.2 Bq·dm-3. The lowest tritium concentrations were found in waters of the Seashore Region rivers (average for 1994–1999 was 1.1 Bq·dm-3). The tritium concentrations in surface waters and in precipitation are still higher than that of natural level. The data obtained show that tritium concentration in the water of rivers might depend on the size of drainage area. The observed seasonal variations of tritium concentration in the precipitation collected in Warsaw and at the Mount Sniezka indicate the stratospheric source of tritium. It was found that about 30% of tritium deposited with precipitation is removed to the Baltic Sea with river waters.

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.

Polygeneration system based on PEMFC, CPVT and electrolyzer: Dynamic simulation and energetic and economic analysis