# System-level testing and qualification of environmental sensors for nuclear decommissioning

Alejandro Urena Acuna, Julien Favrichon, Eric Cantrel, Pierre-Alexis Robin, Aurelien Balier, Marie-Anne Lissandre, Tadec Maraine, Frédéric Saigné, Jérôme Boch

► To cite this version:

Alejandro Urena Acuna, Julien Favrichon, Eric Cantrel, Pierre-Alexis Robin, Aurelien Balier, et al. System-level testing and qualification of environmental sensors for nuclear decommissioning. EPJ Web of Conferences, 2023, Animma 2023, 288, pp.070014. 10.1051/epjconf/202328807014 . cea-05516014

HAL Id: cea-05516014

https://cea.hal.science/cea-05516014v1

Submitted on 17 Feb 2026

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# System-level testing and qualification of environmental sensors for nuclear decommissioning

## Introduction

Decommissioning of nuclear facilities uses electronic equipment (sensors, mobile vectors, robots, remotely operated arms, etc.) in an irradiating environment. However, the effect of radiation is one of the main factors affecting the reliability of electronic components and systems. The evaluation of electronic components and systems makes it possible to identify the technologies most tolerant to irradiating environments and to determine which sub-functions are the most sensitive.

Then, to characterize the radiation response of Components off-the shelf (COTS) devices, it is essential to design a strategy that allows us to qualify them and determine the blocks prone to fail during a mission in a civilian nuclear environment. Hence, this work explores a system-level testing and qualification methodology for COTS environmental sensors.

## System-level qualification

<figure><img src="image_2.png" /><figcaption>Fig. 1. System-level testing process.</figcaption></figure>

### Experimental setup & tested devices

Forty sensors of two different lots (L1 and L2) were irradiated to qualify their radiation response. The tested devices were 20 MCP9808 digital temperature sensor and 20 VL53L0X Time of Flight (ToF) distance sensor. Functional and electrical parameters were monitored before, during, and after irradiation. The consumption current ($I_{cons}$) was monitored using a Keysight N6705C power analyzer. The devices communicate under the $I^2C$ protocol with a microcomputer (Nvidia Jetson-nano) and a script was designed to acquire two measurements per second in a CSV file for post-data processing as shown in Fig 2. The VL53L0X was positioned at 160 mm from a target to get a distance reference.

<figure><img src="image_3.png" /><figcaption>Fig. 2. Experimental setup: MCP9808 temperature and VL53L0X ToF distance sensors.</figcaption></figure>

### Irradiation, biasing conditions and qualification criteria

All devices were irradiated with the PRESERVE platform at the Institut of Electronics and Systems (IES) in Montpellier, France with a 320 keV X-rays generator with a 2 mm aluminum filter to eliminate photons with low energies and under a $^{60}$Co source (Fig. 3). The applied dose rate was 240 Gy/h ($SiO_2$) for X-rays and 4,5 Gy/h for $^{60}$Co. All sensors were biased in two different modes during irradiation to determine the worst-case of biasing as depicted in Fig. 2. The “OFF” state, with all pins connected to the ground, and the “ON” state, where the sensor operates in normal biasing mode. The number of tested devices can vary in each experiment.

<figure><img src="image_4.png" /><figcaption>X-rays generator</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>Sensors at
X-rays generator</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>Sensors at
$^{60}$Co source</figcaption></figure>

<caption>Fig. 3. PRESERVE platform and irradiated devices.</caption>

## Results

We seek to demonstrate that the increase in consumption current produced by radiation beyond the datasheet current limit can induce total or partial loss of functions of the sensors. For this reason, a first parameter to monitor is the consumption current of the sensor as a function of the absorbed dose. As an additional qualification parameter, we propose a tolerance of 10% on the accuracy of the sensor measurements.

We observe in Figure 4 the radiation response of the MCP9808 temperature sensor. In Fig. 4(a) the consumption current measurements of lot 1 and 2 irradiated with X-rays. Lot 1 was irradiated in step-by-step mode while lot 2 in continuous mode (CM) with one measurement per minute. We noticed an increase in consumption current for both lots, and we observed that this produces errors in the accuracy of the temperature measurements as shown in Figure 4(b).

### MCP9808 Temperature sensor

<figure><img src="image_7.png" /><figcaption>a) Current ON-state</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>b) Temperature measurement ON-state</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>c) Current OFF-state</figcaption></figure>

<figure><img src="image_10.png" /><figcaption>d) Temperature measurement OFF-state</figcaption></figure>

<caption>Fig. 4. Radiation response of MCP9808 temperature sensors.</caption>

Figure 4 c) and d) show the consumption current and the measurements in the OFF state. In (c) we observe that the consumption current increases from the 240 Gy step. This produces errors in the precision of the measurements shown in Figure 4 d). Devices irradiated with $^{60}$Co showed almost the same behavior than the lot 2 X-rays devices.

### VL53L0X Distance ToF Sensor

<figure><img src="image_11.png" /><figcaption>a) Distance Measurement ON-state</figcaption></figure>

<figure><img src="image_12.png" /><figcaption>b) Distance Measurement OFF-state</figcaption></figure>

<caption>Fig. 5. Radiation response of VL53L0X distance sensor.</caption>

Figure 5 shows the VL53L0X distance sensors irradiated in the ON state. We observe that for lot 1 the consumption current exceeds the 40 mA current limit for the 480 Gy step. This has an impact on the measurements as shown in Figure 5(b), where a total loss of measurements is reported for lot 1. Lot 2 irradiated with X-rays and $^{60}$Co in both biasing modes never exceeded the current limit so, its functionality and accuracy were not affected during the irradiation. This is due to the lot-to-lot variability of the devices.

### Worst-case biasing

As observed in Figures 4 and 5, sensors irradiated in "ON" state showed the highest variation in current consumption and lower dose tolerance than those irradiated in OFF state. This is well known according to the literature, where the application of an electric field during radiation prevents the prompt recombination of charges in the insulating oxides of single transistors, producing a greater electrical degradation in the performance of the devices. Table 1 shows the qualified dose tolerance for both sensors.

<table><caption>Table 1. Qualified dose tolerance of the different sensors.</caption><thead><tr><th rowspan="2">Sensor</th><th colspan="2">Dose tolerance (Gy)</th><th rowspan="2">Worst case biasing</th></tr><tr><th>ON</th><th>OFF</th></tr></thead><tbody><tr><td>MCP9808</td><td>120 Gy L1<br>155 Gy L2</td><td>240Gy L1<br>480 Gy L2</td><td>ON</td></tr><tr><td>VL53L0X ToF</td><td>480Gy L1<br>3000Gy L2</td><td>&gt;3000Gy<br>L1 and L2</td><td>ON</td></tr></tbody></table>

### Conclusions & perspectives

In this paper we show the first steps of a system-level test methodology. In order to validate the test methodology, we confirm the results by a $^{60}$Co irradiation. But in the long term, we seek to use only high energy X-rays. This could represent multiple advantages in terms of speed of testing, maintenance and radioprotection. We have observed that an increase in the consumption current can induce functional failures. We were able to confirm the lot-to-lot variability that influences the radiation response of the devices in addition to determining the worst case biasing mode. These factors must be taken into account for the qualification methodology.

<footnote>A. Urena Acuna¹*, J. Favrichon¹, E. Cantrel¹, P. A. Robin², A. Balier², M. A. Lissandre², T. Maraine³, F. Saigné³, J. Boch³
¹ French Alternative Energies and Atomic Energy Commission (CEA), BP 17171, 30207 Bagnolès-sur-Côze, France, CEA, DES, ISEC, DPME, LNPA, Univ. Montpellier, Marcoule, France
² ISYMAP society 1075 Au Kennedy, 30130 Pont-Saint-Esprit, France.
³ Université de Montpellier, IES-UMR UMCNRS 5214, 660 Rue de St Prieil, Bat 5, 34090 Montpellier, France</footnote>

<footnote>The authors thank the Occitanie region for funding this work within the framework of the PRRI CASIMIR Project. X-rays and $^{60}$Co tests were performed using the PRESERVE platform, which was funded by the Occitanie Region and the EU via ERDF funds</footnote>