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J Radiat Prot > Article-in-Press
Saleh and Kim: Assessment of Source Terms and Potential Doses Due to Steam Generator Tube Rupture of VVER-1200 at the El Dabaa Nuclear Power Plant in Egypt

Abstract

Background

As Egypt ventures into nuclear energy, ensuring the safety and security of its nuclear facilities is paramount. The ongoing construction of the El Dabaa Nuclear Power Plant (NPP) directs the necessity for Egypt to meticulously evaluate the potential outcomes of any conceivable accidents. A focused analysis on design-based accidents such as steam generator tube ruptures (SGTR) is imperative for assessing their impact on the local populace and the environment. Through comprehensive assessments, Egypt aims to enhance the safety protocols of its NPP. This preemptive strategy facilitates the identification and minimization of risk, along with the formulation of efficient emergency response frameworks. Such diligent preparations are essential for cultivating public confidence while ensuring compliance with international safety norms and securing the long-term sustainability of Egypt’s nuclear energy program.

Materials and Methods

The hypothetical scenario of a SGTR at the El Dabaa NPP was modeled using the Radiological Assessment System for Consequence Analysis (RASCAL) code. This model examined the potential consequences of such an accident by incorporating meteorological data from 2013 to 2023 across all seasons to compute the source term, total effective dose equivalent (TEDE), and thyroid dose. Then, these metrics were evaluated against established safety thresholds to determine compliance. The outcomes of this analysis provide critical insights and aid in formulating strategies for effective response to an accident, especially if the calculated doses exceed the permissible limits.

Results and Discussion

The analysis of the worst-case scenario for the SGTR accident at the El Dabaa NPP involves a U-tube breakage above the water level, exacerbated by a concurrent station blackout. This condition potentially leads to a considerable dispersal of radioactive materials, especially within a 0.4 km radius, with a TEDE reaching 4.80×103 mSv during autumn. However, the severity of this worst-case scenario fluctuates with seasonal weather conditions; notably in spring, the highest TEDE was 15 mSv at a 40 km distance. The source term distribution indicates that noble gases account for 31.6%, iodine group for 32.0%, and other sources constitute 36.4% of the total radioactive release. These findings confirmed that TEDE and thyroid dose exceeded the permissible thresholds, thereby highlighting the importance for protective measures to mitigate the potential risks of such accidents.

Conclusion

A comprehensive assessment of SGTR accidents at the El Dabaa NPP emphasizes the critical necessity for stringent safety protocols and protective interventions in worst-case scenarios. By preemptively addressing these risks, Egypt can fortify its nuclear safety framework, emergency response capabilities, and adherence to global safety standards. This proactive stance not only assures the long-term sustainability of Egypt’s nuclear energy program but also solidifies public confidence.

Introduction

Under the stewardship of the Nuclear Power Plants Authority (NPPA), the El Dabaa Nuclear Power Plant (NPP) marks Egypt’s inaugural foray into nuclear energy. The project capacity is 4.8 GW through four Generation III+Vodo-Vodyanoi Energetichesky Reactor (VVER; water–water energetic reactor)-1200 reactors [1]. Rosatom is tasked with the development and construction of this facility, which was designated for nuclear power generation in 1983. The NPPA was granted permission for the El Dabaa NPP in April 2019, and the construction license for the first reactor was issued in 2021. Situated approximately 320 km northwest of Cairo, the first reactor is projected to start commercial operations by 2028. To support the construction, more than 80 structures will be erected at the El Dabaa site through a collaborative effort between Rosatom’s subsidiary Atomstroy export and Korea Hydro & Nuclear Power (KHNP). In addition, Egypt will procure turbine island equipment from KHNP [2, 3].
The U.S. Nuclear Regulatory Commission (NRC) identifies steam generator tube ruptures (SGTR) as a prevalent cause of significant incidents in operational pressurized water reactors (PWRs). Unlike other loss of coolant accidents (LOCA), SGTR requires immediate operator intervention. To curb these failures, the nuclear sector has adopted various strategies including secondary side inspections, advancements in steam generator (SG) design, water chemistry management, and the refinement of eddy current tube inspection techniques. Despite these preventative measures, the risk of SGTR poses a threat of releasing contaminated coolant into the environment via secondary side safety and relief valves. Notably, accumulation of water in the secondary side of the SG can lead to overfill scenarios, thereby exacerbating the radiological impacts and increasing the probability of further failures [4].
The SGs in Russian VVER-1200 are horizontal-shell and tube-heat exchangers that transfer heat from the primary reactor coolant to generate steam for the turbine generators on the secondary side. Factors such as tube degradation, vibrations, stress corrosion, or water hammer can lead to SGTR. In the event of a rupture, the high-pressure coolant and radioactive-steam escapes through the relief valves or condenser off-gas [5]. Over two decades of NPP operations have witnessed SGTR incidents at facilities including Point Beach 1, Surry 2, Prairie Island 1, Ginna, Fort Calhoun, North Anna 1, McGuire 1, Palo Verde 2, Indian Point 2, and Oconee 2 [4, 6], thereby underscoring the importance of diligent oversight and continuous improvement in safety protocols.
The International Atomic Energy Agency mandates that NPP operators undertake a comprehensive assessment of potential risks employing a graded approach, considering even the most unlikely events. This assessment must prioritize the implementation of precautionary and urgent protective measures to prevent or mitigate severe deterministic effects before the release of any considerable amount of radioactive material. To reduce the deterministic impacts and the possibility of stochastic effects, protective actions, and responses should be implemented both preemptively and in the aftermath of radioactive material discharge through ongoing monitoring and assessment of the radiological conditions [7, 8].
This study aims to examine the radiological consequences of a SGTR event with and without offsite power to identify the protective measures for safeguarding the public and the environment from radiological hazards. This analysis utilizes the Radiological Assessment System for Consequence Analysis (RASCAL) computer code [9] to focus on the radiological impact in the vicinity of the NPP unit at the El Dabaa site. The findings can inform the development of an evacuation policy and preparedness plan, facilitating the enactment of effective safeguards against internal and external environmental risks.

Materials and Methods

1. Study Area

Weather data across all four seasons for 10 years (2013 to 2023) at the El Dabaa site were analyzed using the Wind and Rain Rose Plots software (WRPLOT) [10]. Simulations of SGTR events coinciding with station blackout (SBO) and SGTR scenarios with available offsite power were conducted using the RASCAL 4.3.3 code and the study methodology is shown in Fig. 1. In addition, we used Minitab software (Minitab Inc.) [11] to represent the findings of our statistical investigation.

1) Wind rose models

Wind rose diagrams illustrate the average wind patterns and velocities within a specific area over time, which is crucial for predicting the dispersion of radioactive materials following nuclear disasters. These models represent each of the four seasons and provide essential insights into prevalent wind directions (WDs) and frequencies. Figs. 25 display the dominant WDs and speeds for each season, offering a foundational understanding of the environmental factors affecting radiological dispersion.

2) Weather information

The analysis of weather data over a decade (2013 to 2023) included variables such as temperature (T), wind speed (WS), precipitation (R), stability classification (SC), and WD, with statistical evaluations performed using Minitab software. The objective was to identify the representative values for each meteorological parameter. Table 1 presents the representative meteorological data.
Statistical analysis indicated a p<0.005 from the Anderson-Darling test across all weather conditions, leading to the rejection of the null hypothesis that posits a normal data distribution. Consequently, the data were identified as not normally distributed. Based on these findings, representative metrics were selected as the first quartile (Q1), third quartile (Q3), and median to aptly characterize the dataset given its non-normal distribution as illustrated in Figs. 6 and 7 for statistical analysis of temperature in the spring and fall seasons. In addition, the frequencies of each stability class are analyzed according to the Pasquill category, extremely unstable (A), moderately unstable (B), slightly unstable (C), neutral (D), slightly stable (E), moderately stable (F), and extremely stable (G) [12]. Figs. 8 and 9 show the stability classifications during the summer and spring.

3) RASCAL simulation model

The RASCAL software was developed by the Protective Measures Team of the U.S. NRC Operations Center. It serves as an independent tool for predicting the radiation doses and effects in case of radiological incidents, aiding in decision-making and emergency response. RASCAL uses the source term to dose model to estimate the radiation exposure caused by radioactive material to individuals in affected areas.
The latest version, RASCAL 4.3.4, incorporates dose pathways including inhalation of the plume, ground shine from deposited radionuclides, and cloud shine from the airborne plume. Utilizing Gaussian plume modeling, RASCAL simulates the spread of radioactive materials. The fundamental Gaussian puff model in RASCAL, expressed as Equation (1), employs the superposition principle to expand the one-dimensional diffusion equation solution to three dimensions [9, 13].
(1)
X(x,y,z)Q=1(2π)32σxσyσzexp[-12(x-x0σx)2]×exp[-12(y-yσy)2]×exp[-12(z-z0σz)2]
where Q denotes the amount of unconfined material (in Bq or g), and σ indicates the dispersion parameter (in m), which depends on the distance from the release point when combined with a transport device to pass through the center of the puff (x0, y0, z0), and χ denotes the concentration (in Bq/m3 or g/m3).
Radiological assessment studies across various NPPs and accident scenarios have enhanced our understanding of the potential impacts of nuclear incidents. At the Ninh Thuan 1 NPP, the research focused on determining radiation doses from radioactive releases during an International Nuclear Event Scale (INES) level 7 catastrophe, triggered by SBO and LOCA events [14]. Similarly, an assessment for the Advanced Power Reactor (APR)-1400 reactor at Shin Kori Unit 3 estimated radionuclide concentrations and radiation doses in the early phases of serious nuclear incidents, including LOCA and a long-term station blackout (LTSBO) [15]. The Rooppur NPP study assessed the outcomes of a total grid power failure on the Unit-1 VVER-1200 reactor, considering the impact of passive safety emergency core cooling systems (ECCS) during both dry and wet seasons [16]. For El Dabaa, previous research delineated offsite emergency-planning zones for the Egyptian NPP, employing a probabilistic safety assessment to evaluate a major accident scenario (LOCA) in a 1,200 MWt PWR, considering varying atmospheric conditions and their probabilities [7].

(1) Technical specifications

The technical specifications of the VVER-1200 type reactor for the El Dabaa site are listed in Table 2 [13, 14, 17, 18].

(2) RASCAL accident assumptions and scenarios

RASCAL simulations consider the location of the tube rupture in relation to the water level of the SG. A rupture below the water level, termed “partitioned,” results in mixing of SG water with primary system water, thereby diluting the radionuclide concentrations in the steam because of a “partitioning factor.” Conversely, a rupture above the water level, described as “not partitioned,” causes most of the primary coolant to vaporize, thereby considerably increasing the radionuclide emissions.
The simulations consider the release of noble gases relatively unaffected by partitioning, given their stable presence in primary coolant leaks. The assumption for these simulations posits the SGTR above the water line, which represents a worst-case scenario [9, 19].
A prior research [20] developed a database of fission product retention in SGTR sequences and models to assess the effectiveness of different accident control measures for such events. Another study [21] focused on simulating an SGTR accident in the Personal Computer Transient Analyzer (PCTRAN) VVER-1200 nuclear reactor, considering the complete rupture of a single tube. This analysis examined the safety protocols and system responses to assess the potential repercussions of the accident and the capacity of the facility to lessen its impacts. Furthermore, a radiological scenario evaluation for the APR-1400 [22, 23] considered LOCA, SBO, and SGTR incidents. Utilizing PCTRAN APR-1400 for source term derivation and HOTSPOT for dose calculations [24], the study aimed to devise an emergency response strategy to mitigate the radiological consequences under varied meteorological conditions.
Additionally, a study examined the specific characteristics of the corrosive-mechanical damage in the primary circuit header to SG vessel branch welds in VVER-1000 NPPs as shown in Fig. 10 [13]. This analysis also explored the preventive approaches for analogous concerns in VVER-1200 SGs, focusing on operational safety and economic viability. Another study explored the probability of radioactive dissemination following a steam-line breach in a VVER-1200 nuclear power facility. Their findings suggested that effective safety mechanisms considerably reduce the likelihood of radioactive release into the environment, employing the PCTRAN for safety system evaluation [15].
This research further delved into a LOCA scenario to highlight the vitality of the containment system in confining the radioactive materials. Additionally, a computational analysis addressed a grave incident involving LOCA, SBO, and ECCS failure within the VVER-1200 reactor core [9]. This particular study contemplated two scenarios: SGTR concurrent with an SBO (S1) and SGTR with available offsite power (S2), which highlights the paramount importance of preparedness and response mechanisms in nuclear safety management.

① Scenario 1 (no offsite power)

During a LTSBO scenario, the El Dabaa NPP encountered a complete loss of both offsite and onsite alternating current (AC) power, which rendered the AC-powered safety systems nonfunctional. As time progressed, the direct current batteries were also exhausted. This led to the closure of the stop valve of the turbine generator, causing the water to evaporate from the SGs.
A worst-case scenario was assumed when a full double-ended rupture occurred in a U-tube within the SG above the water line that caused steam to be vented from the secondary circuit through the safety relief valve (steam dump valves to atmosphere BRU-A) into the atmosphere.
The subsequent reduction in the SG water levels uncovered the reactor core, causing temperatures to rise. The reactor was manually shut down at 0:00 AM, with radionuclide emissions from the core commencing after an 8-hour interval, according to the default LTSBO delay period outlined in the State-of-the-Art Reactor Consequence Analyses (SOARCA) study. The leakage rate into the SG was recorded at 2 m3/hr, employing the RASCAL default steaming rate starting from 8:00 AM. Overall, this scenario involved a cascade of events including power loss, the sealing of the turbine generator’s stop valve, steam discharge from the secondary circuit, and core exposure, culminating in the release of radionuclides.

② Scenario 2 (offsite power available)

At the onset of this scenario at the El Dabaa NPP, a precipitous decline in the primary system pressure coincided with simultaneous rise in the secondary pressure at 0:00 AM. The reactor was promptly shutdown in response to the drop in primary system pressure, which is speculated to result from a SGTR. Operator interventions estimated a compensatory makeup flow, inclusive of safety injections, at approximately 34,019 kg/hr. The surge in secondary pressure triggered the activation of the high-pressure safety relief valve (BRU-A). This scenario presupposes the rupture site to be above the water line, indicative of a worst-case scenario, with the discharge point located 42.2 m above the ground level.

(3) Input data for meteorological conditions

The transportation and dispersal of radionuclides in the atmosphere are significantly influenced by meteorological variables such as WS, WD, R, and atmospheric SC. RASCAL 4.3.4 mandates the incorporation of meteorological data from 2 hours prior to the release for accurate modeling [9]. To simulate the variances in seasonal weather conditions, specific dates across different months were carefully selected. February was selected to represent winter conditions, November for autumn, July for summer, and April for spring. This approach ensures an accurate representation of weather patterns related to each season during the simulation. To a comprehensive overview of the meteorological trends, Table 1 compiles 96-hour historical weather data for the El Dabaa site, covering the designated periods for the modeling assessment.

Results and Discussion

1. Distribution of the Source Term

Two accident scenarios involving SGTR were selected based on their probability and the potential impact on the surrounding area. The simulations were performed to assess the atmospheric dispersion of hazardous materials at a specific location. RASCAL calculates approximately 70 source terms for the VVER-1200 reactor, representing the release of radionuclides during an accident. These simulations provide insights into the potential radiological environmental effects and assist in establishing exposure limits for at-risk individuals.
The contribution of a radionuclide to the source term is influenced by several critical factors, including the yield of fission products, the physical state and chemical activity of the nuclide, reaction to reduction mechanisms, and the severity of the accident. Fig. 11 presents a comparison of actual activity levels for eight groups in the S1 and S2 SGTR scenarios upon conclusion of the RASCAL simulation. The data indicates that for S1, Noble gases and halogens are predominant in the source term, with total activities of 6.29×1016 Bq and 6.44×1016 Bq, respectively. In scenario S2, alkali metals and noble gases exhibited stronger activities at 8.50×1012 Bq and 5.41×1012 Bq, respectively. The distribution of radionuclide types (noble gases, I, and others) into the atmosphere for both scenarios is illustrated in Figs. 12 and 13. In S1, apporximately 31.6% of noble gases and 32% of I were released, while in S2, these percentages shifted to 34.4% for noble gases and decreased to 3.9% for I. Other groups remained significant contributors, accounting for 36.4% and 61.7% in each scenario, respectively. In condition S1, the ratio of noble gases to I-131 was 3:1, whereas in case S2, the ratio of noble gases to I-131 activity increased significantly to 27:1.
Fig. 14 details the source terms and their cumulative activities of total effective dose equivalent (TEDE) pathways during the transit of the plume for two distinct accident scenarios. Among the radionuclides included in the RASCAL source terms, 18 in S1 and 16 in S2 were identified as the most significant contributors to these pathways. Cs-137, Cs-134, Ru-106*, I-131, I-133, La-140, and Ce-144* consistently exhibited the highest activities in both scenarios, attributed to their lengthy half-lives relative to the interval from shutdown to release. Nonetheless, a pronounced variation in released activity levels was observed between the scenarios.
The particulars of each scenario, such as the specific accident conditions and operating parameters, were crucial in determining the production of H-3 and Co-58. In S2, accentuated by a coolant contamination factor of 30, notable releases of H-3 (8.3×1012 Bq), Co-60 (3.4×109 Bq), and Co-59 (1.4× 1011 Bq) were recorded. Conversely, scenario S1 exhibits significant contributions from radionuclides such as Pu-241 and Te-132, which are derivatives of Am-241 and I-132, respectively, and are generated in larger volumes during SGTR accidents lacking offsite power. The specific volume of activity released depends on a multitude of accident-specific factors including reactor design, scenario nuances, fuel composition, and operational conditions, whereas other radionuclides in the source term posed a minimal impact on the overall dose.

2. Radiological Doses

In the initial stages of a severe nuclear incident, several measures and strategies are undertaken to mitigate the aftermath and effectively manage the crisis. Protective action guidelines (PAGs) are instrumental in this phase, directing decision-making processes and safeguarding public health and safety. PAGs are established by regulatory authorities and are based on scientific and technical considerations. Certain key aspects of the PAGs during the early phase of a nuclear accident are listed in Table 3 [25].
The immediate hours post-accident are critical for executing decisions aimed at protecting the populace and the environment, enabling an evaluation of the consequences and impact of the incident [26]. Figs. 15 and 16 present the maximum TEDE in mSv relative to downwind distance for two distinct accident scenarios (S1 and S2), under varying meteorological conditions delineated in Table 1. Fig. 15 reveals that the peak maximum TEDE is observed at approximately 0.4 km from the emission source, diminishing with the increased distance. In extreme scenarios such as during autumn and spring, doses at 0.4 km reach 4,800 and 4,200 mSv, respectively, with a reduction observed as distance extends. The spring season consistently exhibits increased dose levels, peaking at 15 mSv at 40 km.
These dose fluctuations are attributed to variations in atmospheric SC ranging from B (moderately unstable), C (slightly unstable), D (neutral), and E (slightly stable), among other meteorological parameters. Fig. 16 demonstrates the maximum TEDE under scenario S2 with offsite power availability, noting a peak dose of 0.44 mSv at 0.4 km, which gradually lessens to 0.02 mSv at 3.2 km during autumn. In spring, the plume extends to approximately 6.4 km, with a maximum dose of 0.01 mSv. These differences in dose levels are influenced by a combination of onsite elements such as source terms, operational conditions, safety system availability, and mitigation efforts, as well as offsite factors including atmospheric stability, WS and direction, temperature, and proximity to the source term.
The doses illustrated in Fig. 13 align closely with those reported for the VVER-1200 nuclear reactor in Bangladesh [16]. Specifically, under a LTSBO scenario both without and with the operation of ECCS over 24 hours during the monsoon season, doses of 4,400 mSv and 3,600 mSv were recorded, respectively, based on site-specific meteorological data. These figures present a contrast to simulations for the El Dabaa site, where a significant leak from the primary to secondary circuit leading to core damage was modeled using the RASCAL code, yielding maximum doses of 1,170 mSv and 2,950 mSv at 2 km distance under stability classes D and F, respectively [7].
Moreover, at the Rooppur NPP in Bangladesh, simulations of a large break LOCA with SBO for the VVER-1200 reactor utilizing Oak Ridge Isotope Generation and Depletion Code-Scale (ORIGEN-S) and HOTSPOT codes calculated doses of 1.01×102 Sv at 0.4 km during the summer. For winter, the maximum dose reached 1.28×102 Sv at 0.4 km, and during the rainy season, it escalated to 1.03×104 Sv at 0.01 km distance [27]. These discrepancies are attributable to differing assumptions across accident scenarios, meteorological data variations, and levels of conservatism in the analyses.
Figs. 17 and 18 depict the thyroid dose distribution across the fall, spring, summer, and winter seasons for two SGTR accident scenarios. Both scenarios exhibited a consistent pattern with elevated doses near the site during the fall, especially within 0.4 km. In scenario 1 (S1), the dose at this proximity is 4.6×104 mSv, whereas in scenario 2 (S2), it is 4.40×101 mSv. As the distance increases in the downwind direction, the doses sharply decline to 40 km, except during the spring.
In S1, the dose at 40 km is 160 mSv, whereas in S2, the plume extends up to 4.8 km with a dose of 0.012 mSv. The reduction in plume concentration is influenced by variations in weather conditions and the presence of the I group, comprising 32% in S1 and 3.9% in S2. Conversely, with varied weather typified by stability classes D and F under LOCA conditions at El Dabaa, thyroid doses at 2 km were reported as 8.00×100 Sv and 2.1×101 Sv, respectively [7].
According to this study, no protective actions are required for SGTR S2. In contrast, the protective effects recommended for SGTR S1 are summarized in Table 4.

3. Pathways’ Relative Importance

In the worst-case scenario S1 (spring season), the temporal effects on the three pathways to TEDE near the release point are analyzed. During the initial plume passage (0 day), inhalation is identified as the predominant pathway, accounting for 99% of the total dose potential. Cloudshine contributes 1.4%, while the ground shine is considered negligible. The dominance of inhalation doses is attributed to a substantial contribution of I-131 to TEDE (31% at 0 day). Conversely, a smaller fraction (2.4%) from the Xe group results in a lesser cloudshine dose. After plume passage, the groundshine dose emerges as the primary contributor to TEDE. The groundshine fraction of the total dose potential progressively increases to 0.95, 0.94, 0.99, 0.99, and 1.0 at 1, 7, 30, 183, and 365 days, respectively. During these intervals, inhalation shifts to a secondary pathway, whereas the impact of cloudshine remains minimal, as depicted in Fig. 19.
In scenario S2, also during the spring season, inhalation significantly outweighs other pathways, contributing 99.9% of the total dose potential at the time of plume passage (0 day). Ground shine poses a minimal effect, with cloudshine accounting for 0.3%. The larger percentage of I-131 in TEDE (25% at 0 day) signifies the predominance of inhalation doses. Furthermore, a reduced proportion (0.2%) from the Xe group yields a lesser cloudshine dose. After the plume disperses, the groundshine dose becomes the key source of TEDE contribution. The groundshine portion of the total dose potential rises to 0.76, 0.81, 0.96, 1.0, and 1.0 at 1, 7, 30, 183, and 365 days, respectively. In these periods, the cloudshine posed minimal influence, with the inhalation serving as the secondary pathway, as illustrated in Fig. 20.
Monitoring and evaluating the deposition of radionuclides from the plume to the ground post-severe accidents is critical. The degree of ground deposition directly influences the permissible groundshine doses to the public, necessitating a thorough assessment owing to its potential impact on flora and fauna. In instances of significant deposition, stringent food consumption restrictions may be required to safeguard public health.

Conclusion

The comprehensive analysis of the potential outcomes from a SGTR incident at the El Dabaa NPP offers critical insights into the hazards such an event may pose. The worst-case scenario examined, featuring a U-tube rupture above the water line during a SBO, demonstrates the risk of substantial release of radioactive material near the facility. Using the RASCAL code along with a decade of meteorological data, the study highlights the significance of assessing potential impacts under various weather conditions. The analysis determined that the TEDE exceeded the acceptable thresholds, reaching 4.80×103 mSv within a 0.4 km radius of the plant during autumn. Nonetheless, the intensity of this worst-case scenario fluctuated with changing weather conditions, noting the highest TEDE at 15 mSv at 40 km away during spring.
The investigation into the source term distribution revealed that noble gases constituted 31.6% of the total activity, with the I group at 32.0% and other sources accounting for 36.4%. These results underline the necessity for effective management and mitigation strategies for the dispersion of various radioactive materials in the event of an SGTR accident. The analysis clearly demonstrates the importance of enacting protective measures to mitigate risks associated with such incidents. Exceedances of TEDE and thyroid dose beyond established thresholds emphasize the critical need to safeguard the local community and the environment.
By preemptively addressing these risks and using the insights gained from this comprehensive analysis, Egypt can enhance the safety protocols and emergency preparedness at the El Dabaa NPP. These proactive measures affirm a dedication to adhering to international safety standards and play a crucial role in fostering public confidence in Egypt’s nuclear energy agenda.
This investigation lays a robust groundwork for the ongoing refinement of safety and emergency response strategies at the El Dabaa facility. Leveraging the insights from this comprehensive review, Egypt is poised to sustain and securely advance its nuclear energy program, ensuring its longevity and safety.

Notes

Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Ethical Statement

This article does not contain any studies with human participants or animals performed by any of the authors.

Data Availability

All datasets used and/or analyzed in the current study are available from the corresponding author on reasonable request.

Author Contribution

Conceptualization: Saleh W. Methodology: Saleh W. Data curation: Saleh W. Formal analysis: Saleh W. Supervision: Kim J. Funding acquisition: Kim J. Project administration: Kim J. Investigation: Saleh W. Visualization: Saleh W. Resources: Saleh W. Software: Kim J. Validation: Saleh W. Writing - original draft: Saleh W. Writing - review & editing: all authors. Approval of final manuscript: all authors.

Acknowledgements

This research was supported by the 2023 Research Fund of the KEPCO International Nuclear Graduate School (KINGS), Republic of Korea.

References

1. Katona TJ. Long-term operation of VVER power plants. In: Tsvetkov P. Nuclear power: deployment, operation and sustainability. IntechOpen. 2011;152-196.

2. World Nuclear News. Contract signed for El Dabaa turbine islands [Internet]. WNN; 2022 [cited 2024 Feb 22]. Available from: https://www.world-nuclear-news.org/Articles/Contract-signed-for-El-Dabaa-turbine-islands?fbclid=IwAR1KQ3BoYS11EjM61Q__ifBwgqmIUQgAa2fkBFaQjtNCfcOR1QmJGcinhdw

3. Dabaa Nuclear NS ENERGY. El Power Project [Internet]. NS ENERGY; 2024 [cited 2024 Feb 22]. Available from: https://www.nsenergybusiness.com/projects/el-dabaa-nuclear-power-project

4. United States Nuclear Regulatory Commission. 0523-R504P-Westinghouse advanced technology: 04:6-Steam generator tube rupture [Internet]. U.S.NRC; 2011 [cited 2024 Feb 22]. Available from: https://www.nrc.gov/docs/ML1121/ML11216A088.pdf

5. MacDonald PE, Shah VN, Ward LW, Ellison PG. Steam generator tube failures. United States Nuclear Regulatory Commission. 1996.

6. Wu JM, Chuang CF. Consequence analysis of a steam generator tube rupture accident. Nucl Technol. 1984;67(3):381-406.
crossref
7. Bakr WF, Abdien AK. Assessing the emergency planning zones for the Egyptian nuclear power plant site. IOSR J Appl Phys. 2018;10(5):76-85.

8. Buglova E. IAEA safety standards in the area of emergency preparedness and response: reference levels, generic criteria and operational criteria. International Conference on Radiation Safety: Improving Radiation Protection in Practice. 2020 Nov 9–20. Vienna, Austria. 353-354.

9. Ramsdell JV, Athey GF, McGuire SA, Brandon LK. RASCAL 4 description of models and methods. United States Nuclear Regulatory Commission. 2012.

10. Jesse L, Cristiane L, Johnson MA. Wind and Rain Rose Plots for meteorological data [Internet]. Lakes Environmental Software; 2016 [cited 2024 May 3]. Available from: https://www.weblakes.com/products/wrplot/resources/lakes_wrplot_view_user_guide.pdf

11. Alin A. Minitab. Wiley Interdiscip Rev Comput Stat. 2010;2(6):723-727.
crossref
12. Jeong HS, Jeong HJ, Kim EH, Han MH, Hwang WT. The annual averaged atmospheric dispersion factor and deposition factor according to methods of atmospheric stability classification. J Radiat Prot Res. 2016;41(3):260-267.
crossref
13. Arzhaev A, Arzhaev A, Makhanev V, Antonov M, Emelianov A, Kalyutik A, et al. Possible in-service damages of steam generators at VVER-1000 and VVER-1200 NPP units and their impact on long-term operation. E3S Web Conf. 2020;209:03005.
crossref
14. Khai NT, Cuong LD. Assessment of radioactive gaseous effluent released from Ninh Thuan 1 nuclear power plant under scenario of INES-level 7 nuclear accident. Commun Phys. 2015;25(4):375.
crossref
15. Uddin GMB, Kim J. Nuclear emergency management using accident consequence analysis code. J Korean Soc Hazard Mitig. 2019;19(4):215-225.
crossref
16. Faisal SI, Islam MS, Soner MAM. Prediction of radioactivity releases for a long-term station blackout event in the VVER-1200 nuclear reactor of Bangladesh. Nucl Eng Technol. 2023;55(2):696-706.
crossref
17. International Atomic Energy Agency. Status report 108: VVER-1200 (V-491) (VVER-1200 (V-491)) [Internet]. IAEA; 2011 [cited 2024 Feb 22]. Available from: https://aris.iaea.org/PDF/VVER-1200(V-491).pdf

18. The State Atomic Energy Corporation ROSATOM. The VVER today: evolution, design, safety. ROSATOM Overseas. 2013.

19. Kowalczik J. Welcome to Rascal Training [Internet]. United States Nuclear Regulatory Commission, Office of Nuclear Security and Incident Response; 2024 [cited 2024 May 3]. Available from: https://ramp.nrc-gateway.gov/landing-page?destination=/codes/rascal/training

20. Jokiniemi J. Steam generator tube rupture scenarios [Internet]. VTT PROCESSES, Aerosol Technology Group; 2000 [cited 2024 Feb 22]. Available from: https://cordis.europa.eu/docs/projects/files/FIKS/FIKS-CT-1999-00007/66628891-6_en.pdf

21. Saha A, Fyza N, Hossain A, Rashid Sarkar MA. Simulation of tube rupture in steam generator and transient analysis of VVER-1200 using PCTRAN. Energy Procedia. 2019;160:162-169.
crossref
22. Alrammah IA. Analysis of nuclear accident scenarios and emergency planning zones for a proposed Advanced Power Reactor 1400 (APR1400). Nucl Eng Des. 2023;407:112275.
crossref
23. El-Hameed AA, Kim J. Machine learning-based classification and regression approach for sustainable disaster management: the case study of APR1400 in Korea. Sustainability. 2021;13(17):9712.
crossref
24. Homann SG, Aluzzi F. HotSpot health physics codes version 3.0 user’s guide. Lawrence Livermore National Laboratory. 2013.

25. International Atomic Energy Agency. Actions to protect the public in an emergency due to severe conditions at a light water reactor. IAEA. 2013.

26. Baeza A, Corbacho JA, Miranda J. Design and implementation of a mobile radiological emergency unit integrated in a radiation monitoring network. IEEE Trans Nucl Sci. 2013;60(2):1400-1407.
crossref
27. Fairuz A, Sahadath MH. Assessment of the potential total effective dose (TED) and ground deposition (GD) following a hypothetical accident at the proposed Rooppur Nuclear Power Plant. Appl Radiat Isot. 2020;158:109043.
crossref pmid

Fig. 1
Study methodology. RASCAL, Radiological Assessment System for Consequence Analysis; TEDE, total effective dose equivalent; SGTR, steam generator tube rupture.
jrpr-2023-00248f1.jpg
Fig. 2
Wind speed and direction for the El Dabaa site in spring.
jrpr-2023-00248f2.jpg
Fig. 3
Wind speed and direction for the El Dabaa site in autumn.
jrpr-2023-00248f3.jpg
Fig. 4
Wind speed and direction for the El Dabaa site in summer.
jrpr-2023-00248f4.jpg
Fig. 5
Wind speed and direction for the El Dabaa site in winter.
jrpr-2023-00248f5.jpg
Fig. 6
Temperature statistical analysis during spring.
jrpr-2023-00248f6.jpg
Fig. 7
Temperature statistical analysis during the fall.
jrpr-2023-00248f7.jpg
Fig. 8
Stability classification during the summer.
jrpr-2023-00248f8.jpg
Fig. 9
Stability classification during the spring.
jrpr-2023-00248f9.jpg
Fig. 10
Steam generator of the Vodo-Vodyanoi Energetichesky Reactor [13]. 1: Steam header, 2: Feedwater inlet, 3: Feedwater header, 4: Heat exchange tubes, 5: Main coolant inlet, 6: Main coolant outlet.
jrpr-2023-00248f10.jpg
Fig. 11
Radionuclide activity levels in various groups.
jrpr-2023-00248f11.jpg
Fig. 12
Contribution of all radionuclide groups as a percentage (steam generator tube ruptures concurrent with an station blackout [S1]).
jrpr-2023-00248f12.jpg
Fig. 13
Contribution of all radionuclide groups as a percentage (steam generator tube ruptures with available offsite power [S2]).
jrpr-2023-00248f13.jpg
Fig. 14
Top-ranked source terms and their cumulative activities on total effective dose equivalent pathways.
jrpr-2023-00248f14.jpg
Fig. 15
Maximum total effective dose equivalent (TEDE [mSv]) as a function of downwind distance under four different weather conditions for the steam generator tube ruptures concurrent with an station blackout (S1) accident scenario.
jrpr-2023-00248f15.jpg
Fig. 16
Maximum total effective dose equivalent (TEDE [mSv]) as a function of downwind distance under four different weather conditions for the steam generator tube ruptures with available offsite power (S2) accident scenario.
jrpr-2023-00248f16.jpg
Fig. 17
Four seasons thyroid dose variation with distance during the steam generator tube ruptures concurrent with an station blackout (S1) accident scenario.
jrpr-2023-00248f17.jpg
Fig. 18
Thyroid dose variation with distance during the steam generator tube ruptures with available offsite power (S2) accident scenario across four seasons.
jrpr-2023-00248f18.jpg
Fig. 19
Relative importance of pathways to total effective dose equivalent (TEDE) (steam generator tube ruptures concurrent with an station blackout [S1]).
jrpr-2023-00248f19.jpg
Fig. 20
Relative importance of pathways to total effective dose equivalent (TEDE) (steam generator tube ruptures with available offsite power [S2]).
jrpr-2023-00248f20.jpg
Table 1
El Dabaa Meteorological Data for RASCAL Simulation
Season Time (mo/d/hr) WS (m/s) WD (º) R (mm) T (ºC) SC
Autumn 11/17 6:00 AM 3.0 270 No rain 26 C
11/18 3:00 AM 3.0 270 26 D
11/19 3:00 AM 2.0 270 25 E
11/19 3:15 AM 2.0 270 25 E
11/20 3:30 AM 3.0 248 26 D
11/20 3:45 AM 3.0 270 26 D
11/20 4:00 AM 3.0 248 26 D
11/20 6:00 AM 3.0 270 26 D

Spring 4/17 6:00 AM 2.0 293 No rain 19 E
4/18 3:00 AM 4.0 315 18 D
4/19 3:00 AM 2.0 338 18 E
4/19 3:15 AM 5.0 293 20 D
4/20 3:30 AM 5.0 315 18 C
4/20 3:45 AM 5.0 315 20 C
4/20 4:00 AM 4.0 315 18 D
4/20 6:00 AM 2.0 315 18 E

Summer 7/17 6:00 AM 3.0 338 No rain 27 D
7/18 3:00 AM 4.0 293 26 B
7/19 3:00 AM 5.0 315 27 C
7/19 3:15 AM 3.0 315 27 D
7/20 3:30 AM 3.0 293 26 D
7/20 3:45 AM 4.0 293 27 C
7/20 4:00 AM 3.0 315 26 B
7/20 6:00 AM 4.0 315 26 D

Winter 2/17 6:00 AM 2.0 270 No rain 19 C
2/18 3:00 AM 3.0 270 18 C
2/19 3:00 AM 2.0 270 18 C
2/19 3:15 AM 3.0 225 17 D
2/20 3:30 AM 2.0 248 17 C
2/20 3:45 AM 3.0 270 18 C
2/20 4:00 AM 2.0 248 17 E
2/20 6:00 AM 2.0 270 17 C

RASCAL, Radiological Assessment System for Consequence Analysis; WS, wind speed; WD, wind direction; R, precipitation; T, temperature; SC, atmospheric stability classes.

Table 2
Technical Specifications of the VVER-1200 Reactor for RASCAL Simulation
Parameter Value
Type Generic PWR with large, dry containment [9]
Latitude 31.0472°
Longitude 28.5009°
Time zone World offset from GMT/UTC +2
Reactor power 3,200 MWth [17, 18]
Average burnup in the reactor 40,000 MWd/MTU [17, 18]
Discharge burnup in spent fuel storage 50,000 MWd/MTU [17, 18]
Number of assemblies in the core 163 [17, 18]
Containment volume 2.5×106 ft3 [14]
Coolant mass 1.728×107 kg [17, 18]
U-tubes inside each SG 10,978 [17, 18]
Primary coolant flow rate per SG 4,479.166667 kg/s [17, 18]
Coolant flow rate per SG tube 0.408012996 kg/s [17, 18]

VVER, Vodo-Vodyanoi Energetichesky Reactor; RASCAL, Radiological Assessment System for Consequence Analysis; PWR, pressurized water reactor; GMT, Greenwich Mean Time; UTC, Coordinated Universal Time; MWth, megawatts thermal; MWd/MTU, megawatt-days per metric ton of uranium; SG, steam generator.

Table 3
Importance of Protective Action Guidelines and Related Preventative Measures in the Early Phases
Protective actions PAGs [25]
Evacuation 10–50 mSv (TEDE)
Sheltering

Iodine tablets thyroid blocking 250 mSv (thyroid dose)

PAG, protective action guideline; TEDE, total effective dose equivalent.

Table 4
Suggested Protective Actions for Steam Generator Tube Ruptures S1
Dose calculated for this study Suggested protective action for S1
Max TEDE, 15 mSv (40 km) worst-case (spring) Evacuation or sheltering
Thyroid dose up to (24 km) 330 mSv Distribution of Iodine thyroid blocking tablets

S1, scenario 1; TEDE, total effective dose equivalent.

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