SUMP PLUGGING ISSUE CONCERNING NPP EXPERIMENTAL … 2019 - Final Papers/06. Mattei J… · 28, 1992, the BARSEBACK-2 nuclear power plant loss-of-coolant accident has led to the ECCS

The 9TH European Review Meeting on Severe Accident Research (ERMSAR2019) Log Number: 006Clarion Congress Hotel, Prague, Czech Republic, March 18-20, 2019

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SUMP PLUGGING ISSUE CONCERNING NPPEXPERIMENTAL PROGRAM ON CHEMICAL EFFECTS

IMPACT OF INSULATION COMPOSITION: POSSIBLE CREATION OFSODIUM SILICATE

Jean-Marie MatteiIRSN

BP 17, 92262 Fontenay-Aux-Roses, [email protected]

Bo Ni, Jean RochBERTIN Technologies

10B, Avenue Ampère, 78180 Montigny le Bretonneux, [email protected]; [email protected]

Vojtech Soltesz, Jozef Batalik, Ivan VicenaVUEZ

Hviezdoslavova 35, P.O. Box 153, 93439 Levice, [email protected]; [email protected]; [email protected]

Marek Liska, Maria ChromcikovaAlexander Dubcek Trencin University

VILA - Joint Glass Center of the Institute of Inorganic Chemistry SASŠtudentská 2, Trenčín, SK-91150, Slovakia

[email protected]; [email protected]

ABSTRACT

The operational characteristics of the filtration function used on a reactor during the recirculation phase ofthe safety injection system (SIS) and containment spray system (SS), in the event of a primary system breakin the containment (loss of coolant accident (LOCA)) is one of the main concern of safety worldwide. The"Institut de Radioprotection et de Sûreté Nucléaire" (IRSN) has conducted a large program of research onthis issue. A general overview of the literature was conducted between October 1999 and November 2000.This led to a methodology and technical specifications for an experimental program, which was carried outuntil 2003. Results demonstrated that essential actions had to be performed to deal with the question of thefilter efficiency at all the plants. Nevertheless, certain questions remained open; in particular the LOCAinduced long-term debris effect, as a combined action of the temperature and the chemical composition ofthe solution in the sumps. The issue of chemical effects is the transformations of materials inside thecontainment due to the combined impact of temperature and chemicals. It includes the transformation ofdebris either already carried, on the strainers or in the containment. The head loss across the containmentsump screen in the post-LOCA environment could increase due to the collection of corrosion products onfibrous insulation.


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On this technical issue, a program aimed at increasing knowledge of the chemical effects on the fiber bedcreated on the filtering systems during recirculation was performed by IRSN with VUEZ Company andTRENCIN academy (SLOVAKIA). Using the results of this program, a model has been established.In 2011, additional topics to be assessed as downstream effects have been identified leading to carry out anew research program using the VIKTORIA loop inaugurated in 2012.This document presents a recent study related to the impact of insulation composition at high temperatureon chemical effects. The results underlined the fact that tests carried out at low temperature are not fullyrepresentative. They underlined also that depending on chemical composition of insulation, critical strainerhead loss can appear due to possible creation of sodium silicate.

Moreover, this phenomenon:- Could also take place at the level of the fuel assemblies during recirculation process and impact

significantly the primary cooling;- Could have a critical effect on recirculation process carried out at high temperature close to 140°C

during severe accident progression.Additional research program is necessary to be carried out to confirm the occurrence of this phenomenon.

KEYWORDSPWR, LOCA, filtering system, recirculation

1. INTRODUCTION

The assessment of the operational characteristics of the filtration function used during the recirculationphase of the safety injection system (SIS or ECCS) and containment spray system (SS), in the event of aprimary system break in the containment, is one of the most important concerns for reactor safety. On July28, 1992, the BARSEBACK-2 nuclear power plant loss-of-coolant accident has led to the ECCS failure dueto the plugging of its sump screens. To cope with this problem, the international community assessmentsfirstly focused on the BWR units and modifications were implemented till 1996, based on the existingknowledge at that time. Then, assessments on PWR units have been conducted or are in progress worldwide.

From 1999, a large assessment was performed by the "Institut de Radioprotection et de Sûreté Nucléaire"(IRSN) for the French pressurized reactors. A general overview of the literature was conducted betweenOctober 1999 and November 2000, which resulted in a definition for an approach methodology and in thewriting of technical specifications for an experimental program of studies on the sump plugging risk.

Studies were carried out for the different sizes of primary breaks: large, intermediate and small LOCA. Toestimate the risk involved in each case, the following points were assessed:

An inventory of debris generated. This consists of the following types: Glass wool thermal insulation fibers, Paints, particulates and dust present in the containment,

Vertical transfer of debris, Structural modification of debris in the containment, Horizontal transfer of debris at the bottom of the containment, Filtration efficiency and modification of sump hydraulics / air and debris ingestion.

The subjects giving rise to important questions were collected and it was decided to do a correspondinglarge scale experimental program in order to answer the questions raised from a preliminary study.


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The following points were currently under experimental investigation: IVANA loop (VUEZ / SLOVAKIA): study of mechanical action on the debris of falling water, VITRA loop (EREC / RUSSIA): study of horizontal transfer speed of debris, MANON loop (VUEZ / SLOVAKIA): study of strainer head loss, ELISA loop (VUEZ / SLOVAKIA): establishment of different correlations.

Nevertheless, questions remained open; in particular LOCA induced long-term chemical effects on thedebris, as a combined action of the temperature and the chemical composition of the solution in the sumps.The issue of chemical effects is the transformations of materials inside the containment due to the combinedimpact of temperature and chemicals. It includes the transformation of debris, either already carried on thestrainers or in the containment. The head loss across the containment sump screen in the post-LOCAenvironment could increase due to the collection of corrosion products on fibrous insulation. Concerns havebeen raised about the potential for different ion corrosion products to significantly block a fiber bed andincrease its head loss.

Little information was available on corrosion product release with representative post-LOCA conditions.No study has been performed in the world on this specific item. In 2003, IRSN managed a preliminary studyon the chemical effects with its contractor VUEZ which demonstrated the creation of precipitates increasingthe head loss of the fiber bed deposited on the filters of the Safety Injection System (SIS) and Spray system(SS).

A program to set up knowledge of the chemical effects on the fiber bed created on the filtering systemsduring recirculation was proposed, in 2004, and performed with the VUEZ and TRENCIN academy(SLOVAKIA). Using the results of these investigations, a head loss model was established depending ondebris characteristics, temperature and chemical characteristics of the sumps solution, on fiber bedcompression and on distribution of particles in the fiber bed.

To be able to qualify strainers with appropriate conditions of transport of the debris, construction of arelevant test facility, called VIKTORIA, was decided by IRSN/VUEZ in 2011. From 2012, IRSN/VUEZstarted test plan using VIKTORIA loop to study for foreign reactors chemical effects and downstream effectsand their impact on the main strainer head loss and to investigate also “in-core” downstream effects in thefuel assemblies due to possible deposition of debris and occurrence of chemical process on their anti-debrisand mixing grids [4, 5].

Considering the results of the carried out tests, IRSN intended to confirm that depending on insulationcomposition and on temperature, chemical phenomena occurring in the fiber bed could lead to head lossexceeding very quickly mechanical limits of the filter or avoiding a satisfactory cooling of the fuelassemblies. This thought was shared by VUEZ and considered as a research item covered commonly byIRSN, BERTIN and VUEZ [1].

This paper describes the test results of:- A test at high temperature (Tw) considering a loading debris case without particles,- A test at ambient temperature (Twamb) considering the same loading debris case without particles.

The objective of the proposed tests was to obtain data on effects of temperature, insulation composition onhead loss evolution of the strainer without consideration on chemical effects due to additional species likesoda or boric acid. For this purpose, the VIKTORIA loop was used.

Test procedure was in accordance with test plan [2].


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2. TEST EQUIPMENT

The VIKTORIA hydraulic test facility is used for the tests. This loop is specifically designed to performintegrated large scale chemical ECCS sump and downstream performance assessments. VIKTORIA loop isa flexible facility fully capable of performing traditional separate effects investigations such as strainer headloss tests, quantification of strainer fiber by-pass, and fuel assembly clogging tests.

The VIKTORIA hydraulic test facility consists of six main interconnected segments (Figure 1, Figure 2):1. Debris preparation tank – a tank where the debris that would be transported to the strainer is

introduced and homogenously mixed.2. Submerged material tank – a tank for placing coupons and samples of representative chemical

reactive materials that would be submerged in the post-LOCA pool.3. Spray system tank – a tank for placing coupons and samples of representative chemical reactive

materials that would be exposed to containment spray.4. Strainer tank – a tank for placing a full scale segment of a strainer. The debris preparation tank is

connected to the Strainer tank by a flume to prototypically simulate the debris transport to thestrainer.

5. Downstream modules – a series of parallel chambers that can be used to place fuel assemblies,valves, heat exchangers, or other components downstream of the strainer.

6. External tank - a tank for placing a full scale segment of a strainer and retention baskets dependingon the design of the reactor.

The VIKTORIA hydraulic test facility has 60 kilowatts of electrical heaters capable of up to 90°C steadystate operation. A bank of four parallel pumps is capable of generating flow rates up to 40m3/h through thestrainer. It has a full complement of flow, pressure, and temperature instrumentation for monitoring andprocess controls. A stand-by generator backs up the power supplies in the event of loss of off-site power.

Depending on the test objectives, two lines simulating fuel rods are used. The first one is equipped witha module including 289 (17x17 in compliance with the fuel assembly (FA) design of the NPP) surrogates’fuel rods and anti-debris and mixing grids. The second one is equipped with a module including 25 (5x5)surrogates’ fuel rods and anti-debris grid with 3 heated fuel rods.

Figure 1: VIKTORIA Loop


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Figure 2: VIKTORIA Loop / General layout


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3. TEST INPUTS

Quantity of all input materials are specified in chapter 4.

3.1. Solution

Test Tw was executed at high temperature and Twamb was carried out at ambient temperature. The testswere performed without addition of chemical species (H3BO3, NaOH).

3.2. Debris in the pool

Materials considered for the tests represented the significant structural materials transported to the bottomof the containment after a loss of coolant accident, which could interact with the solution carried from thesumps by the containment spray system (CSS) and the safety injection system (SIS). These materials wereplaced in the recirculating solution.

No metallic materials were used. Settled debris (not transported) and leached debris (debris not transportedbut contributing to corrosion process and consequently to chemical effects) were not installed.

For the test in agreement with the results of the upstream analysis, the debris bed contained insulations PSI713, 734QN, 725QN and 714 (Figure 3 – Figure 6).

The materials were thermally aged. Aging process consisted to heating of the debris at 300°C during 8h, asproposed in the NEI guide [3]. Samples after ageing process are presented on the left side of Figure 3 toFigure 6. The basic chemical composition of original and treated insulations was determined by X-rayfluorescence analysis (S8 TIGER spectrometer with QUANT-EXPRESS™ measurement method). Theamount of lubricant residual was determined by thermal gravimetric analysis (TGA).

Insulations PSI 713, 725 QN and 734 QN have a comparable chemical composition. All are glass fibers.The main difference is in the amount of lubricant which is organic compound.

Insulation 714 is mineral wool and has significantly higher amount of Al2O3 and ~ 20 w.% lower amount ofSiO2 then other insulation types. Content of Na2O and CaO is also different however total amount iscomparable (~22 w.% ) for each insulation type. The difference between the composition of original 714fibers and treated fibers can be explained by the inhomogeneity of analysed samples.

After this treatment, the debris transported to the screen were prepared using a high pressure water jet asproposed in the NEI guide [3]. The corresponding quantities used for the tests are provided in chapter 4.


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Figure 3: Insulation PSI 713

Figure 4: Insulation 714


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The chemical composition (weight %) of used fibers is provided in the following Table 1. Correspondinguncertainties are: 5 to 10% for values >10%; 10 to 30% for values from 0,1 to 10%, and 20 to 300% forvalues below 0,1%.


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Table 1: Chemical composition (weight %)

Comp.713 714 725 734

Original Treated Original Treated Original Treated Original Treated

SiO2 62.79 63.28 40.12 49.76 63.00 63.95 64.79 64.95

Na2O 14.90 15.00 7.21 10.29 15.59 15.71 15.37 15.44

CaO 7.42 7.48 14.01 12.25 8.04 8.15 8.26 8.27

MgO 2.89 2.86 2.48 2.62 2.19 2.25 2.33 2.33

Al2O3 2.34 2.32 22.21 15.90 1.83 1.86 1.77 1.79

SO3 0.81 0.61 0.11 0.22 0.21 0.21 0.21 0.18

K2O 0.65 0.64 3.75 2.76 0.65 0.66 0.63 0.64

MnO 0.39 0.42 0.22 0.31 0.64 0.63 0.54 0.54

Fe2O3 0.14 0.20 6.00 4.31 0.55 0.61 0.54 0.54

Cl 0.05 0.05 0.01 0.14 0.04 0.05 0.04 0.04

BaO 0.05 0.05 0.05 0.06 0.15 0.155 0.14 0.14

TiO2 0.03 0.04 1.04 0.73 0.15 0.16 0.15 0.16

Cr2O3 0.02 0.02 0.01 0.02 0.05 0.05 0.05 0.05

CoO - - - - - - <0.01 <0.01

CuO - - - - <0.01 <0.01 <0.01 <0.01

MoO3 - - 0.03 0.02 <0.01 <0.01 <0.01 <0.01

NiO - - - - - - - <0.01

PbO - - - - 0.01 0.01 0.01 0.01

SeO2 - - - - - - - <0.01

SrO - - - - 0.02 0.02 0.02 0.02

ZnO - 0.01 - 0.02 - - - -

ZrO2 <0.01 <0.01 0.11 0.07 0.01 0.01 0.01 0.01

Lubricantresidue(organic)

7.53 7.02 2.65 0.52 6.87 5.52 5.14 4.90


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3.3. Coolant pH

The tests were carried out using demineralised water and pH was measured to identify any corrosion process.

4. TEST PARAMETERS

4.1. Test matrix

Test matrix used for test Tw and Twamb is provided in Table 2.

Table 2: Test matrix

Summary informationQuantities

ParameterI/1 Sump Volume Containing Chemicals

10 m3

I/2 Sump Volume Containing DebrisI/3 Screen Size 2.67 m2

I/4 Flow Rate 21.10 m3/hI/5 Approach Velocity 0.22 cm/s

I/6 Temperature Profile80

Ambient °CI/7 Theoretical Debris Bed Thickness 9.84 cmI/8 Particulate to fiber mass ratio 0.644 -

II/1 PSI 713 Fiberglass (Glass Wool Panel)2.727 kg0.045 m3

II/2 734 QN Fiberglass (Glass Wool Mattress)2.155 kg0.067 m3

II/3 725 QN Fiberglass (Bulk Glass Wool)9.164 kg0.131 m3

II/4 714 (Glass Wool Performed Pipe Section)1.527 kg0.019 m3

II/5 Coatings - Inside ZOI N/A kgII/6 Unqualified Coatings - Outside ZOI N/A kgII/7 Latent Fibers 0.124 kgII/8 Latent Dirt/Dust N/A kg

III/1 PSI 713 Fiberglass (Glass Wool Panel)N/A kgN/A m3

III/2 734 QN Fiberglass (Glass Wool Mattress)N/A kgN/A m3

III/3 725 QN Fiberglass (Bulk Glass Wool)N/A kgN/A m3

III/3 714 (Glass Wool Performed Pipe Section)N/A kgN/A m3

III/5 Coatings - Inside ZOI N/A kgIII/6 Unqualified Coatings - Outside ZOI N/A kgIII/7 Latent Fibers N/A kgIII/8 Latent Dirt/Dust N/A kgIV/1 Aluminum areas 0 m2

V/1 Boron concentration range 0 ppmV/2 pH ~7-9 -V/3 NaOH additives 0 w.%


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4.2. Temperature profile

For first test: Tw, temperature was defined by the maximal temperature reached on VIKTORIA loop (closeto 80°C). The second test: Twamb was performed at ambient temperature.

5. TEST RESULTS

5.1. Test Tw

Test Tw was started 14th April 2016 at 08:00 and was terminated 15th April 2016 at 09:00. The test time isin table below (Table 3).

Table 3: Tw test time line

Time [hh:mm] Action14th April 2016

07:30 – 08:00

Stabilization of parameters Head loss 0.0 kPa; Flow-rate 21.1 m3/h; Temperature 81.6°C; pH 7.8

08:00 Batch # 1A08:10 Batch # 1B08:20 Batch # 2A08:30 Batch # 2B08:40 Batch # 3A08:50 Batch # 3B09:00 Batch # 4A09:10 Batch # 4B09:20 Batch # 5A09:30 Batch # 5B09:40 Batch # 6A09:50 Batch # 6B10:00 Batch # 7A10:10 Batch # 7B10:20 Batch # 8A10:30 Batch # 8B10:40 Batch # 9A10:50 Batch # 9B11:00 Batch # 10A11:10 Batch # 10B11:20 Batch # 11A11:30 Batch # 11B11:40 Batch # 12A11:50 Batch # 12B12:00 Batch # 13A12:10 Batch # 13B12:20 Batch # 14A12:30 Batch # 14B12:40 Batch # 15A12:50 Batch # 15B13:00 Batch # 16A13:10 Batch # 16B


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Time [hh:mm] Action

15:00

Head loss 0.7 kPa; Flow-rate 21.0 m3/h; Temperature 80.6°C; pH 8.1

19:00

Increase of head loss Head loss 1.1 kPa; Flow-rate 21.1 m3/h; Temperature 79.8°C; pH 8.2

15th April 2016

08:37 Head loss exceeds 20 kPa

09:00Test termination due to the high head loss.The sample of fiber bed and of the circulating fluid was taken for theanalyses.

The evolution of main parameters (versus time) during the test is provided in the figures below.

Figure 7: Tw test start up


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Figure 8: Head Loss and temperature evolution (Tw)

Figure 9: Head Loss and pH evolution (Tw)


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Figure 10: Head Loss and downstream turbidity evolution (Tw)

Figure 11: Total flow-rate and water level (Tw)


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5.2. Test Twamb

Test Twamb was started on 20th April 2016 at 08:00 and was terminated 22th April 2016 at 08:15 (Table 4).

Table 4: Twamb test time line


07:30 – 08:00

Stabilization of parameters Head loss 0.1 kPa; Flow-rate 21.1 m3/h; Temperature 14.3°C; pH 7.7

08:00 Batch # 1A08:10 Batch # 1B08:20 Batch # 2A08:30 Batch # 2B08:30 - 09:00 Injection line clean-up09:00 Batch # 3A09:10 Batch # 3B09:20 Batch # 4A09:30 Batch # 4B09:40 Batch # 5A09:50 Batch # 5B10:00 Batch # 6A10:10 Batch # 6B10:20 Batch # 7A10:30 Batch # 7B10:40 Batch # 8A10:50 Batch # 8B11:00 Batch # 9A11:10 Batch # 9B11:20 Batch # 10A11:30 Batch # 10B11:40 Batch # 11A11:50 Batch # 11B12:00 Batch # 12A12:10 Batch # 12B12:20 Batch # 13A12:30 Batch # 13B12:40 Batch # 14A12:50 Batch # 14B13:00 Batch # 15A13:10 Batch # 15B13:20 Batch # 16A13:30 Batch # 16B

15:00



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08:00


22th April 2016

08:00

Test termination. Head loss 3.4 kPa; Flow-rate 21.2 m3/h; Temperature 24.6°C; pH 8.6

The evolution of main parameters (versus time) during the test is provided in the figures below.

Figure 12: Twamb test start up


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Figure 13: Head Loss and temperature evolution (Twamb)

Figure 14: Head Loss and pH evolution (Twamb)


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Figure 15: Head Loss and downstream turbidity evolution (Twamb)

Figure 16: Total flow-rate and water level (Twamb)


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6. ASSESMENT OF THE RESULTS

6.1. Test Tw

The test Tw was started on 14th April 2016.

The initial head loss after the batching was 0.7 kPa. However at 19:00, an increase of head loss wasobserved. After 22:00, the gradient of increase raised to ~1 kPa/hour, and the final head loss was close to20 kPa on the next morning.

During the test, increase of pH (from 7.8 to 8.4) was noted due to the dissolution of alkalies from the fibers.The downstream turbidity decreased from 25 NTU to a constant value of 10 NTU even during the increaseof head loss showing that the fiber bed was not destroyed during the increase of head loss.

The test was interrupted on 15th April 2016 at 09:00 when the head loss increased above 20 kPa.

The aim of our corresponding assessment was to understand what was the origin of this sudden and criticalincrease of the strainer head loss. It was difficult to assume that this origin was linked with mechanicalphenomena like excessive compression of the fiber bed. Consequently, our assessment was mainly focusedon potential occurrence of chemical effects.

For this purpose, samples of fiber bed were assessed using SEM/EDS measurement. Results are providedin Appendix A (the samples are identified as B24w instead of Tw for the measurement by SEM/EDS).Nevertheless, they cannot be considered totally relevant because they were realized at the end of the testwith dried samples that are different from the conditions met during the completion of the test.

With regards to occurrence of chemical effects, we considered as probable the creation of sodium silicateand we tried to identify it.

Sodium silicate also called “water glass” is the common name for compounds with the formulaNa2(SiO2)nO) [https://en.wikipedia.org/wiki/Sodium_silicate].

Figure 17: Sodium silicate [https://en.wikipedia.org/wiki/Sodium_silicate].

The SEM/EDS results of the fiber bed sample confirmed the creation of sodium silicate type particles.

With regards to the group of corrosion species like SiO2-CaO-Na2O, they were also morphologically wellrecognised by their smooth surface resembling the frozen liquid (Figure 18). Thus, the formation of waterglass can be assumed in the corresponding areas.


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Figure 18: Corrosion products with “frozen liquid” morphology

The glass composition (especially high content of Na+; above 16.0 w.%) and mechanical properties of fibers(fiber diameter ~5µm) causing extremely low resistance of insulation against the hot water or alkali watersolution leads to high corrosion of fibers. Therefore, sticky layer (layer of sodium silicate) can be formedduring the interaction with solution (as it was shown by SEM/EDS during the test Tw).

This phenomenon was not really identified during previous tests involving metallic coupons as aluminum,but also a high quantity of particles.

6.2. Test Twamb

The second test Twamb was performed with the same configuration as test Tw but at ambient temperature.The aim of this test was to perform the same test with minimisation of potential corrosion effect of water tothe glass fibers. Test Twamb was started on 20th April 2016 at 08:00 and was terminated 22th April 2016 at08:15.

The head loss after the batching was 3.8 kPa. During the test, just the slight decrease of head loss independence on the increasing water temperature was observed.

During this test, the rising pH was also observed (increase from 7.7 to 8.6) due to the dissolution of alkalisfrom the fibers.


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7. CONCLUSION

By completion of this series of tests, IRSN and VUEZ have significantly increased their knowledge relatedto the behavior of fiber bed head loss depending on temperature and chemical composition of insulation.

They underlined also the fact that campaign of tests carried out at low temperature cannot be considered asrepresentative of all phenomena that can occur.

Critical increase of strainer head loss was observed at high temperature after 12 hours during Tw. Thisphenomenon was not really identified during previous tests involving aluminum and also a high quantity ofparticles. Its most probable origin can be attributed to chemical effects occurring during a stay at hightemperature.

Our assumption was that sodium silicate which constitutes a sticky compound was formed. Investigationand measurement confirmed this possibility that critical strainer head loss could appear due to the creationof sodium silicate depending on chemical composition of insulation and mainly on Na and K contents.

Moreover, we can assume that this phenomenon could also be observed depending of Arrhenius law, at anytemperature considering an increase of corrosion rate of a factor 2 for each step of 10°C. Consequently, thisphenomenon:- Could also take place at the level of the fuel assemblies during recirculation process and significantly

impact the core cooling;- Could have a significant effect on recirculation process carried out at high temperature close to 140°C

during severe accident progression.

Additional research program is necessary to be carried out to confirm the occurrence of this phenomenon.

REFERENCES

1. “Second revision of the Agreement between IRSN and VUEZ on the construction and operation of anuclear safety facility”, October 2010

2. J.M. Mattei (IRSN), “Impact of insulation types and retention baskets test plan”, August 20163. Nuclear Energy Institute, “ZOI Fibrous Debris Preparation: Processing, Storage and Handling”,

Revision 1, January 20124. NEA/CSNI/R(2013)12, Updated Knowledge Base for Long Term Core Cooling Reliability, 20th

December 20135. IRSN report DAI/2012/006: Experimental Program on Chemical Effects and Head Loss Modelling –

JM. Mattei, I. Vicena, V. Soltesz, J. Batalik, M. Liska, A. Klementova, 2012


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APPENDIX A

All samples were sputtered by a graphite layer to prevent charging during exposition by an electron beam.Sputtering of layer approximately 20 nm thick was performed by sputter coater Bal-Tec SCD 500.Analyses were performed by EDX (Energy Dispersive X-Ray Spectroscopy) on HITACHI electronmicroscope equipped with ThermoFisher SDD analyser of rtg. radiation. A picture recorded by electronmicroscope (scale is on the bottom right) proceeded analyses. On the picture analysed areas/points are drawnfrom where according X-Ray spectra were captured. Captured spectra with identified elements follow eachfigure. Quantitative analyses are based on the assumed stoichiometry as indicated by the present compoundsin the corresponding tables.

The SEM pictures of original 714, 725 QN and 734 QN fibers are presented on Figure A- 1 toFigure A- 3.

Figure A- 1: SEM Picture of original 714 insulation

Figure A- 2: SEM Picture of original 725 QN insulation


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Figure A- 3: SEM Picture of original 734 QN insulation

Hereafter are provided for different samples taken from the fiber bed created during Test Bw, the contentsof the assessed parts (Figure A-4 to Figure A-10 for SEM/EDS analysis of samples B24W20, B24W21,B24W24, B24W26, B24W27, B24W28, and B24W29).

The summary results comparing the chemical composition of initial insulation and analyses results ofevaluated areas/points are presented in Table A-1.

Figure A-4: SEM Picture of sample B24W20 Figure A- 5: SEM Picture of sample B24W21


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Figure A- 6: SEM Picture of sample B24W24 Figure A- 7: SEM Picture of sample B24W26

Figure A- 8: SEM Picture of sample B24W27 Figure A- 9: SEM Picture of sample B24W28


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Figure A- 10: SEM Picture of sample B24W29


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Table A- 1: Summary results

Sample/ Picture

Area/ point

Composition [w.%]

Na2O SiO2 CaO MgO AI2O3 K2O TiO2 Fe2O3 MnO SUMNa2O+SiO2+CaO

PSI 713 --- 15.00 63.28 7.48 2.86 2.32 0.64 0.04 0.20 0.42 92.2 85.76

714 --- 10.29 49.76 12.25 2.62 15.90 2.76 0.73 4.31 0.31 98.9 72.30

725 QN --- 15.71 63.95 8.15 2.25 1.86 0.66 0.16 0.61 0.63 94.0 87.81

734 QN --- 15.44 64.95 8.27 2.33 1.79 0.64 0.16 0.54 0.54 94.7 88.66

B24W20 B24W1 15.74 65.88 10.48 2.80 2.39 0.69 0.00 1.01 1.02 100.0 92.10

B24W26 B24W12 14.14 65.45 11.18 2.60 2.19 0.63 0.00 2.02 1.79 100.0 90.77

B24W27 B24W27 14.77 65.82 10.32 3.07 2.29 0.61 0.00 1.80 1.33 100.0 90.91

B24W28 B24W14 14.61 64.13 9.03 4.57 3.15 0.54 0.00 2.43 1.53 100.0 87.77

B24W29 B24W15 10.31 63.00 6.19 9.56 6.42 0.42 0.00 2.22 1.87 100.0 79.50

B24W21 B24W2 12.64 60.08 16.98 2.27 1.97 0.95 0.00 2.22 2.89 100.0 89.70

B24W21 B24W3 13.17 67.06 11.15 3.04 2.55 0.60 0.00 1.16 1.27 100.0 91.38

B24W24 B24W8 11.26 69.38 5.21 5.41 6.66 0.39 0.00 0.74 0.94 100.0 85.85

B24W24 B24W10 12.09 68.47 8.43 5.37 3.02 0.58 0.00 1.05 1.00 100.0 88.99

B24W24 B24W11* 9.42 36.07 49.50 2.04 1.91 0.00 0.00 0.52 0.53 100.0 94.99

B24W28 B24W13 20.33 58.46 5.51 8.01 4.39 0.35 0.00 1.61 1.34 100.0 84.30

B24W29 B24W16 9.54 60.25 5.16 13.87 6.55 0.37 0.00 1.87 2.39 100.0 74.95

*the composition of investigated precipitate is different from the others and contains mainly CaO

Documents

SUMP PLUGGING ISSUE CONCERNING NPP EXPERIMENTAL … 2019 - Final Papers/06. Mattei J… · 28, 1992, the BARSEBACK-2 nuclear power plant loss-of-coolant accident has led to the ECCS