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Nuclear #3, Radiologic Risk.

Nowadays, it is common to find NRBQ (Nuclear, Radiologic, Biologic, Chemical) teams among emergency services.

To achieve success it is very important to train a lot and to have a deep knowledge of this kind of risks.

Today, in this post, I am going to talk about radiologic risk and its Spanish legislation, which is written by the Nuclear Authority in Spain (Consejo de Seguridad Nuclear).


Emergency groups

The first point to consider it is how to identify the teams which are going to manage the emergency. The NRBQ emergency teams are not going to do recuperation works, their target is the security of the citizens and save their lives (in Spain).

We can find the max level of exposition for the emergency teams  in the RD 1564/2010. Moreover CSN (Nuclear Security Board) advertised a technic guide to inform how to apply that legislation.

Group 1

Urgent actions in the accident place.

(Save lives, prevent serious injury or prevent a worsening of the accident that could result insignificant doses to the public)

The director of the emergency, through the radiological group, makes every effort to keep the dose levels of the staff below the level of occurrence of severe deterministic health effects included in Annex Table VI.5 VI.

International recommendations by the CSN  recommended to the Spanish Regions a max value of  dose for this group in 500 mSv. Exceptionally, and to save human lives may exceed these values.

The people who will do these jobs could receive higher dose limits for exposed workers laid down in RPSRI * so  they must be informed, trained and volunteers and it should be excluded pregnant women.

However, Table 5.5 of the CSN technical guide collects quantitative radiological criteria for implementing protective measures taken from the International Basic Safety Standars (BSS) of the IAEA (International Atomic Energy) established as a measure of protect medical advice before a new exposure or if the employee so requests in dose limit of 200 mSv.

Group 2

Emergency protection measures and other actions to protect the population.

The emergency director through radiologic group will do all efforts to reduce the dose to the staff during the emergency below max annual dose limit for the exposure in one year requirement  in 50 mSv effective dose by RPSRI.

It has to be taken into account when setting the dosimeters of the staff who will intervene in the emergency.

Emergency zones and intervention development

Very similar to the zones of hazardous material intervention but with different nomenclature and taking into account that the end of one and the beginning of the next is determined by the dose rate.

Urgent measures zone

It is the interior of the bounded zone, in which it is necessary to take certain protective measures to prevent the emergency teams of receiving higher doses than laid down in DBRR for staff intervention group 2 and to prevent the population receive higher doses than the doses established in the intervention levels for urgent protective measures. This area will include the zone where the exposure level exceed 5 mSv / h.

Alert zone

It is the zone in which it is necessary to take protective measures to prevent the population receives doses higher than emergency teams. This area will include the zone where the exposure is expected to exceed 100 mSv / h.

Free zone

Outside the warning area, which is not necessary to apply protective measures because the doses are lower than those established intervention levels . The next figure show the definition of the areas of planning, showing the arrangement of zones and zone criteria apply in both cases.

In the first moments of an emergency you may not have the means to determine the level of exposure around the stage in which it has occurred. In these cases the DBRR provides the following criteria to determine the scope and dimensions of the zones, in open spaces and indoors.
In open spaces:

  • Urgent measures zone will be the circle whose centre is the focus of risk and whose radius is 100 mts.
  • Alert zone is the annulus whose centre is the source of risk and whose inner radius is 100 mts and 200 mts outside.
  • Free zone is outside the Alert Zone.

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Nuclear #2, Manual para primeros actuantes en emergencias radiológicas


Este documento es complementario al artículo sobre el curso de gestión de emergencias radiológicas que os dejé anteriormente. En el se detallan todo sobre los procedimiento y normas de actuación en las emergencias de este tipo.

Sigue leyendo Nuclear #2, Manual para primeros actuantes en emergencias radiológicas

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Nuclear #1, Gestión de emergencias radiológicas

En este artículo voy a compartir documentación relativa al curso de «Gestión de emergencias radiológicas» realizado en la Escuela Nacional de Protección Civil e impartido por el Consejo de Seguridad Nuclear.

Este creo que es un tema muy interesante a tener en cuenta ya que muchas veces, es más el miedo debido al desconocimiento lo que nos bloquea y no nos deja actuar correctamente.

¿Qué es la radiación?

El fenómeno de la radiación consiste en la propagación de energía en forma de ondas electromagnéticas o partículas subatómicas a través del vacío o de un medio material.

La radiación propagada en forma de ondas electromagnéticas (rayos UVrayos gammarayos X, etc.) se llama radiación electromagnética, mientras que la radiación corpuscular es la radiación transmitida en forma de partículas subatómicas (partículas α, neutrones, etc.) que se mueven a gran velocidad en un medio o el vacío, con apreciable transporte de energía.

Si la radiación transporta energía suficiente como para provocar ionización en el medio que atraviesa, se dice que es una radiación ionizante. En caso contrario se habla de radiación no ionizante. El carácter ionizante o no ionizante de la radiación es independiente de su naturaleza corpuscular u ondulatoria.

Son radiaciones ionizantes los rayos X, rayos γ, partículas α y parte del espectro de la radiación UV entre otros. Por otro lado, radiaciones como los rayos UV y las ondas de radio, TV o de telefonía móvil, son algunos ejemplos de radiaciones no ionizantes.

En el siguiente documento os dejo las presentaciones del curso de «Gestión de riesgos radiológicos», espero que sean de vuestro interés. Este es el primer artículo de los tres que voy a escribir sobre este curso, en las próximas publicaciones compartiré el manual de primeros actuantes y la directriz básica, no te los pierdas!

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Second point to consider in fires of steel-framed buildings (3/11)

Emergency Response Plan

If we have knowledge about the emergency response plan we will be able to know where the hazardous areas are and what kind of materials are there accumulate inside the structure and we will know the protection fire system implemented in that area.

The first step when developing an emergency response plan is to conduct a risk assessment to identify potential emergency scenarios. An understanding of what can happen will enable you to determine resource requirements and to develop plans and procedures to prepare the building. The emergency plan should be consistent with your performance objectives.

At the very least, every facility should develop and implement an emergency plan for protecting employees, visitors, contractors and anyone else in the facility. This part of the emergency plan is called “protective actions for life safety” and includes building evacuation (“fire drills”), sheltering from severe weather such as tornadoes, “shelter-in-place” from an exterior airborne hazard such as a chemical release and lockdown. Lockdown is protective action when faced with an act of violence.




The emergency response plan it’s an alive document, it means this document is always being updated by the responsible and the emergency services have to participate actively. This let emergency services have a deep knowledge of the situation in case of emergency.

But, what are the most important questions are we going to ask ourselves in steel-framed buildings to develop the emergency response plan?

  1. Fire load inside the structure and situation.
  2. Fire protection systems.

The first it’s the main point for emergency services because on this depends available time before the structure collapse.

In this link you will find an interesting guide to develop industry emergency response plans.

If you need some help with your emergency response plan don’t hesitate contact me.

Links: Ready

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First point to consider in fires of steel-framed buildings (2/11)


The time

Tic, tac, tic, tac…The bell rings and the firefighters go to the fire but, for how long has been the fire running?

This is the most important question we have to ask ourselves when we go to fire in a steel-framed buildings.

We can estimate approximately when the fire has started but it depends if it occurs in the morning, in the afternoon, in the evening or at night. The most difficult task is estimate the fire time at night.

But how could we try to prevent an accident and save our lives in steel framed buildings?

Firstly, I’m going to analyse the steel composition in order to know how the material behaviour is in high temperatures.

Analyzing steel composition

Creep Strength

The high temperature strength of materials is generally expressed in terms of their «creep strength» – the ability of the material to resist distortion over long term exposure to a high temperature. In this regard the austenitic stainless steels are particularly good also stipulate allowable working stresses of each grade at a range of temperatures. The low carbon versions of the standard austenitic grades (Grades 304L and 316L) have reduced strength at high temperature so are not generally used for structural applications at elevated temperatures. «H» versions of each grade (eg 304H) have higher carbon contents for these applications, which results in significantly higher creep strengths. «H» grades are specified for some elevated temperature applications.

Although the duplex stainless steels have good oxidation resistance due to their high chromium contents, they suffer from embrittlement if exposed to temperatures above about 350°C, so they are restricted to applications below this.

Both martensitic and precipitation hardening families of stainless steels have high strengths achieved by thermal treatments; exposure of these grades at temperatures exceeding their heat treatment temperatures will result in permanent softening, so again these grades are seldom used at elevated temperatures.

Structural Stability

The problem of grain boundary carbide precipitation was discussed under intergranular corrosion. This same phenomenon occurs when some stainless steels are exposed in service to temperatures of 425 to 815°C, resulting in a reduction of corrosion resistance which may be significant. If this problem is to be avoided the use of stabilised grades such as Grade 321 or low carbon «L» grades should be considered.

A further problem that some stainless steels have in high temperature applications is the formation of sigma phase. The formation of sigma phase in austenitic steels is dependent on both time and temperature and is different for each type of steel. In general Grade 304 stainless steel is practically immune to sigma phase formation, but not so those grades with higher chromium contents (Grade 310) with molybdenum (Grades 316 and 317) or with higher silicon contents (Grade 314). These grades are all prone to sigma phase formation if exposed for long periods to a temperature of about 590 to 870°C. Sigma phase embrittlement refers to the formation of a precipitate in the steel microstructure over a long period of time within this particular temperature range. The effect of the formation of this phase is to make the steel extremely brittle and failure can occur because of brittle fracture. Once the steel has become embrittled with sigma it is possible to reclaim it by heating the steel to a temperature above the sigma formation temperature range, however this is not always practical. Because sigma phase embrittlement is a serious problem with the high silicon grade 314, this is now unpopular and largely replaced by high nickel alloys or by stainless steels resistant to sigma phase embrittlement, particularly 2111HTR (UNS S30815). Grade 310 is also fairly susceptible to sigma phase formation in the temperature range 590 to 870°C, so this «heat resistant» grade may not be suitable for exposure at this comparatively low temperature range and Grade 321 is often a better choice.

In the following video we can see how the structural stability is affected and finally the building collapse.


Environmental Factors

Other factors which can be important in the use of steels for high temperature applications are carburisation and sulphidation resistance. Sulphur bearing gases under reducing conditions greatly accelerate the attack on stainless alloys with high nickel contents. In some instances Grade 310 has given reasonable service, in others grade S30815, with a lower nickel content is better, but in others a totally nickel-free alloy is superior. If sulphur bearing gases are present under reducing conditions it is suggested that pilot test specimens be first run under similar conditions to determine the best alloy.

Thermal Expansion

A further property that can be relevant in high temperature applications is the thermal expansion of the particular material. The coefficient of thermal expansion is expressed in units of proportional change of length for each degree increase in temperature, usually x10-6/°C, μm/m/°C, or x10-6cm/cm/°C, all of which are identical units. The increase in length (or diameter, thickness, etc) can be readily calculated by multiplying the original dimension by the temperature change by the coefficient of thermal expansion. For example, if a three metre long Grade 304 bar (coefficient of expansion 17.2 μm/m/°C) is heated from 20°C to 200°C, the length increases by:

3.00 x 180 x 17.2 = 9288 μm = 9.3 mm

The coefficient of thermal expansion of the austenitic stainless steels is higher than for most other grades of steel.


Analyzing the Cardington Test

In the slide 31, we can see that the highest temperature was achieved in 57 minutes, if I know exactly when the fire started I can find out approximately which the structure situation is. But if I don’t know this task and I have to go into the building to rescue a person, how could I do this with security? In that case we will need to be able to read the structure signals.


Thermo-cameras are frequently used in firefighter services, we can use this great tool to analyse the structure situation.

The slide 32 show how can we notice the difference between heating and cooling, the squares of the structure are the last part of the structure in heating and the last in cooling, in fact we can estimate what phase occurs at the moment. Moreover, with the thermo-camera we can see which the beam temperature is and know how it is affected.

But it isn’t enough to determinate the security into the structure, there are other points we must be able to evaluate to guarantee the success in this kind of emergency, we will see the second point in the next post.  Please leave your comment, I would be grateful for your feedback.

Source: Atlas Steels Australia