RADON CORRECTIVE ACTIONS Effectiveness Tested in the pilot ...

RADON CORRECTIVE ACTIONS

Effectiveness Tested in the pilot house

Dr. Borja Frutos Vázquez. Phd. Architect.

Institute for Building Science Eduardo Torroja - (CSIC)

Radon generation

Transport/Entry:

Accumulation : RISK for occupants

Advection : (PB > PA) and Diffusion

Main mechanism of radon entry

Convection

Institute for Building Science Eduardo Torroja (CSIC). Borja Frutos


Common pathways

1 . Air gaps through walls

2. Diffusion through slabs materials.

Advection in cracks and joints

3. Diffusion/advection in walls

4. Through drainage pipes and water waste systems.

5. In crawl space bad ventilated.


Borja Frutos. Instituto de Ciencias de la Construcción Eduardo Torroja (CSIC)

Contribution to radon concentrationTheoretical Approach

Concrete Slab (DIFFUSION)Cracks and Joints (ADVECTION)

E. Muñoz y B. Frutos (2017)

“A finite element model development for

simulation of the impact of slab thickness,

joints, and membranes on indoor radon

concentration”


Joints have the main contribution

Nuclear Safety Council. 2017

Radon estimation.

Maps and LimitsRegulation

Fuente Existing buildings New Buildings

European Recomendation. (90/143/EURATOM): 400 Bq/m3 200 Bq/m3

WHO (2009) 100 Bq/m3 100 Bq/m3

Eurpean Directive (BSS-2013) 300 Bq/m3 300 Bq/m3


Strategies

In soil depressurization

To evacuate gas before entering into building

Radon Barrier

To reinforce gas tightness

Ventilation

By gas dilution with external air

Remediation Action can be referred: 3 basics strategies

Natural

Mechanical


SUMPS:

Objective: Extend the pressure field

• Number of suction points, net, etc.

• Area, soil permeability

COLECTOR.

To evacuate the gas

AIR OULET

Natural (Wind, Stack) or Forced.

- Power of the fan (if necesary)

Extractor

Colector

Sump, drenaige net

Depressurization Systems


The aim:

Designing a depressurization system for the area to be treated.

(Extension of the pressure field): Guaranty value -10Pa in all area

Parameters

• Building area (m2) to be covered

• Taking into account foundation barrier

• Sub slab aggregate permeability

Number of suction points.. Or NET

Power of the mechanical fan



Sumps and caption elements



Using crawl space

Pressurization

Big areas



Existing buildings.

Radon sump and

radon Well.

New buildings

Existing buildings.

Walls foundations!!!

Barrier Systems


Reduce radon transport by diffusion

Need to be installed in every Surface in contact with the soil.

Membranes Characteristics

- Low diffusion coefficient. (Order 10-11 m2/s)- High mechanical resistances: To adapt differential movements , joints, cracks, etc.

• Tear resistance. (Structural movements)• Puncture resistance. (For root resistance, operators footstep, etc) • Elongation and traction resistance (Joints, differential movements between

elements) • Long life durability. Chemical compatibility

Under slab Above the slab

Barrier Systems


- MANUFACTURED. MULTILAYER DESIGN: With Alum FoilWith fiber mesh….

- SPRAYED “IN SITU”. LIQUID

Barrier Systems


Multilayer: Example: RMB 30 (Monarflex)Polietileno + poliéster fiber..

SINGULAR POINTS.

Solutions for: Overlap. Joints Pipes

2 ways:

1. Dilution by air change

External air (10-20 Bq/m3)

Indoor air (>100 Bq/m3)

2. Pressure state modification (only in mechanical ventilation not balanced)

P int

P soil

P int

P soil

Ventilation

Mixture concentration


Effectiveness study. Pilot House

Objetive:

“To study the effectiveness of remedial actions”

a) To build a housing prototype in a very high radon concentration area

b) To study radon entry. Radon generation and accumulation.

c) To install some remedial actions (different periods) and to study effectiveness

Coordinated project

• Institute for Building Science Eduardo Torroja - CSIC

• University of Cantabria

Founded by: Spanish Nuclear Safety Council (CSN)


Soil properties Location: Cuidad Rodrigo. Salamanca.Uranium Mine

Spain. Exposure potential radon map (CSN) Radio content in soil. (1.012 Bq/kg) more than 20 times a “common” soil

Radon concentration in soil (1 m depth) 250.000 Bq/m3.

Permeability: 10-12 m2

Rn Index

(building)

222Rn Bq/m3 (SOIL)

Perm.Low

< 4. 10-13 m2

Perm. Medium

4. 10-13 m2

4. 10-12 m2

Perm. High

> 4.10-12 m2

Low<200 Bq/m3 <30.000 <20.000 <10.000

Medium200 – 400

Bq/m3

30.000 –100.000

20.000-70.00010.000-30.000

high> 400 Bq/m3 >100.000 >70.000 >30.000


Building Prototype

2 floors: Communications between two spaces

Constructions caracteristiques

• Walls made of bricks.

• Concrete slab in basement.

• Soil aggregate under slab 150 mm thickness. •Gravel 10-30 mm.

•No waterproof membrane


Building Prototype


Laboratory

Building Prototype


1st Phase. Radon evolutionAverage radon concentration (4 winter months)

• Basement 39 385 Bq/m3

• 1st floor 6 855 Bq/m3

Correlation • Atmospheric Pressure drop of 3 000 Pa (30 mBar)

Increase of 90 000 Bq/m3 225 % more

• Increase or pressure (300 Pa) due wind velocity (8 m/s)

Increase of 900 Bq/m3 2.3 %

• Temperatures varying (night and day)

Radon diary varying

• Rains. (Also pressure drop)

increase Radon concentration.

Humidity in soil make it less permeable and so, the dry terrain beneath the house can act as a sump.


2nd Phase. Radon mitigation solutions

Radón en

el terreno

Succión

natural

Radón en

el terreno

Succión

natural

Radón en

el terreno

Succión

forzada 80w

Radón en

el terreno

Succión

forzada 80w

Radón en

el terreno

Presión

forzada 80w

Radón en

el terreno

Ventilación forzada en

sótano de 80 w

Radón en

el terreno

Barrera frente al paso de radón

Testing remedial solutions by strategies:

Sump in natural conditions.

a) Under concrete slab

b) Outside foundation

Sump with mechanical fan

a) Under concrete slab

b) Outside foundation

Sump with positive pressurization

Under concrete slab

Basement with a mechanical ventilation Underfloor ventilation

Radon barrier

Elastomer Liquid system

(Effect of the foundation barrier)


1- Sump in natural conditions.Underneath concrete slab

Suction in sump under concrete slab by wind effect

Radón en

el terreno

Succión

natural

PVC 125mm pipe

Sump made in situ with bricks


System installed

0

10.000

20.000

30.000

40.000

50.000

60.000

70.000

80.000

90.000

100.0001-4

-06

2-4

-06

3-4

-06

4-4

-06

5-4

-06

6-4

-06

7-4

-06

8-4

-06

9-4

-06

10-4

-06

11-4

-06

12-4

-06

13-4

-06

14-4

-06

15-4

-06

16-4

-06

17-4

-06

18-4

-06

19-4

-06

20-4

-06

21-4

-06

22-4

-06

23-4

-06

24-4

-06

25-4

-06

26-4

-06

27-4

-06

28-4

-06

29-4

-06

30-4

-06

Co

ncen

tració

n R

n (

Bq

/m3)

Sotano (Bq/m3)

Planta 1 (Bq/m3)



Radon concentration

Temperature:

Wind

In days (8-10 m/s)

Atmospheric pressure

Rains

CORRELATION

BasementBq/m3

%

Average period

1.742 96

Days with 8 m/s

300 99

1- Sump in natural conditions.


2- Sump in natural conditions.External location

Radón en

el terreno

Succión

natural

Suction in sump located outside foundation.

Allow working outside of the living area.

Suspected: The influence of the foundations as a barrier in sub slab depressurization technique


2- Sump in natural conditions.External location

Basement % 1st floor %

Average16.607 Bq/m3

583.213 Bq/m3

53

Windy days1.200 Bq/m3

96300

Bq/m395

Possible explanation for lower effectiveness: The influence of Foundation as a barrier


3 and 4- Sump with a fan

2 different locationFan: Up to 160 Pa with 50 watt

Radón en

el terreno

Succión

forzada 80w

Radón en

el terreno

Succión

forzada 80w


3 and 4- Sump with a fan

Baseme

nt

(Bq/m3)

1st Floor

(Bq/m3)

Basem

en %

1st

Floor

1 %

Sump Inside. Natural 1 742 603 96 % 91 %

Mechanical 349 479 99 % 93 %(2%)

(40%)Sump Outside. Natural 16 607 3 213 58 % 53 %

Mechanical 327 480 99 % 93 %

The fan can solve the barrier of the foundation


5- Positive pressurization

INITIAL (Bq/m3) AFTER (Bq/m3) REDUCCTION (Bq/m3) REDUCCTION %

basement 1st Floor basement 1st Floor basement 1st Floor basement 1st Floor

39 385 6 855 271 388 39 114 6 467 99 94

Mechanism of reduction:Pressurization of soil under de building forces the gas to look for other ways

Radón en

el terreno

Presión

forzada 80w

Fan 80 W

Other possibilities


6- Under floor ventilation



39 385 6 855 10 072 307 29 313 6 548 74 96

Radón en

el terreno

Ventilación forzada en

sótano de 80 w

Fan 80 W

Mechanism of reduction:The under floor space (basement in this case) acts as a sump

Inflow

Outflow. Fan


7- Radon Barrier



39.385 6.855 1.446 434 37.939 6.421 96 94

Mechanism of reduction: Barrier to stop (reduce) radon flux.

Diffusion coefficient (1,96.10-9 m2/s); Liquid apply (no joints), Polyurethane 1000 kg/m3

Mechanical properties: 200% Elongation ( allow differential movements); Tensile Strength 120 kg/m2

Radón en

el terreno

Barrera frente al paso de radón


Sump

200

400

800

1.6

00

3.2

00

6.4

00

12.8

00

25.6

00

51.2

00

0

39.385

6.855P. 1ª

P. Sótano

1.742

603

16.607

3.213

409

368

349

479

327

480

271

380

10.072

307

1.446

434

Límite de riesgo

P. Sótano

P. Sótano

P. Sótano

P. Sótano

P. Sótano

P. Sótano

P. Sótano

P. Sótano

P. 1ª

P. 1ª

P. 1ª

P. 1ª

P. 1ª

P. 1ª

P. 1ª

P. 1ª

CO

NC

EN

TR

AC

IÓN

IN

ICIA

L E

N P

LA

NT

A 1

CO

NC

EN

TR

AC

IÓN

IN

ICIA

L E

N S

ÓT

AN

O

6.8

55 B

q/m

3

39.3

85 B

q/m

3

INITIAL

• underneath

• outside

• Underneath 56 W

• Underneath 80

W

• Outside 80 W

mech

an

ical

Natu

ral

Pressurization

Under floor

ventilation

Radon barrier

39.3

85 B

q/m

3

6.8

55 B

q/m

3

Actuation Limit (EURATOM 90)

Effectiveness


Effectiveness


Barriers

Indoor ventialtion

Crawl space Natutalventilation

Crawl space Forcedventilation

Pressurization

Sump. Natural

Sump. Forced

Presencia interior de Radón ( Bq/m3)Tipo de solución

BRE (Building Research Establishment. UK)

Thank you for your attention

Institute for Construction Sciences Eduardo Torroja. IETcc-CSIC

(www.ietcc.csic.es)

Borja Frutos: [email protected]


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