ACTIVATE SHELTER: An Adaptive Shelter Infrastructure in Rooppur, the Nuclear Arena of Bangladesh

Bangladesh University of Engineering & Technology, Department of Architecture, Faculty of Architecture and Planning, Dhaka

Project idea

Background
Bangladesh started her nuclear journey on November 04, 2017, through the inauguration of the construction work of the Nuclear Reactor I in Rooppur Nuclear Power Plant, Pabna. This is the country’s largest project to address the ever-increasing power crisis. It is expected that the first of the two 2.4Gw reactors will go in operation by 2025. About 25,000 workers (domestic and foreign) with 5000 Russian employees are working under a leading Russian company ‘Rosatom’ for the construction of RNPP. Bangladesh Govt. has built a condominium of 20 storied apartment complex named ‘Rooppur Green City’ for the accommodation of Russian officials in Rooppur. Rooppur union has a population numbering 18,225, with an ever-increasing density of 647 prs/sq km. Most of the local people are farmers, fishermen and construction workers and their living environment is outdoor oriented, as they dwell in courtyard centric homesteads and work in agricultural lands, brick fields and the adjacent river Padma.
The initiation of RNPP evokes a set of questions about the radiation safety of this mass population in case of an extreme scenario, as history indicates at a great loss of lives, livelihood and shelter in cause of the recurrence of nuclear disasters around the world naming Chernobyl, Fukushima, Three mile island etc.

Aim & Objectives
This project head starts with these core questions on the table:
1. What will be the solution for protecting local people from exposure to direct radiation in a disaster scenario in Rooppur, Bangladesh?
2. If the solution is a shelter, what will be its shielding mechanism?
3. How will the shelter perform as a regular building during normal times, especially in the climate of Bangladesh, where it’s necessary to invite daylight and wind flow inside a building, contradicting the basic mechanism of a fallout shelter, as these two are the most dangerous elements to let inside in disaster scenario?
4. What will be the functional purpose of the shelter in normal scenario and why?
This project investigates into these questions and attempts to provide a design solution for a safe and adaptive infrastructure in such environmental and socioeconomic context of Rooppur, Bangladesh.

Findings of Literature Review
Shelter / Evacuate
For reducing radiation exposure, there are 3 principles: time, distance, and shielding. Radiation levels are extremely dangerous immediately after the disaster, but the levels reduce rapidly, in just hours to a few days. Availing shelter is the immediate step according to radiation safety regulations. After the fallouts have precipitated, it is safest to leave shelter and participate in an orderly evacuation.

Access of Radiation in a Building
Nuclear fallout consists of radioactive dust that spread with the wind immediately after the disaster. After the fallout settles onto the ground and roofs of buildings, the rays can access the buildings in various ways. The means of access of radiation are:
1. Ground direct contribution: Rays coming from the ground directly into the shelter without interacting with the intervening wall barriers.
2. Wall scattered contribution: Rays coming from the ground into the shelter after interacting with particles of material in the wall barrier.
3. Sky-shine contribution: Rays entering the shelter after inter- acting with air particles or foreign matter suspended in the air.
4. Roof contribution: Radiation coming from fallout on the roof, and entering the shelter through the roof material.
Another source of radiation is the surrounding big trees. Their brunches and leaves accumulate radionuclides.


Control of Exposure
The fallout shelter must withstand radiation in both times, when the radionuclides are in the air as well as when they have precipitated over the ground. It needs to proof radiation for at least the timeframe from disaster outbreak to orderly evacuation. There are three basic ways for protection from radiation.
1. Geometry, design so that shelter occupant is out of the direct path of radiation
2. Barrier, placing a heavy shield between radiation and the shelter occupants
3. Distance, getting away from the source of radiation.

In areas where basements can be built, geometry is normally the least expensive. Material with high radiation absorption capacity such as water, mustard green field (landscape), concrete (building material) work as good barriers of radiation.

Project description

Identification of Vulnerable Sector & Selection of Site
According to keyhole concept, after an explosion the most vulnerable zone around a nuclear powerplant is the 2-mile ring (3.2 km) and the 5-mile (8 km) downwind zone. Rooppur’s wind rose map indicates southeast and northwest wind flows. Therefore the vulnerable zones can be identified. For planning purpose, the area around RNPP is divided into 160 sectors by a web of radial and circular grid spaced 1 km each. The sectors’ density has been analyzed in the 2-mile (3.2 km) ring to identify the denser sectors. The sectors in exclusion zone (1.6 km radius) where no habitation is allowed, needs relocation of population. The other sectors are grouped into less vulnerable and more vulnerable types by the basis of the presence of nearby potential shelters that can hold mass population in times of disaster. Rooppur Green City and Ishwardi EPZ (Export Processing Zone) are such potential shelters. As per the travel distance to the safe air zone, the farthest sector is identified as more vulnerable. The site for the shelter is selected nearby. The site is located just out of the 2-mile (3.2 km) ring.

Mapping Site Forces
The site has a central position surrounded by communities, which ensures easy access in the shelter. It is surrounded by waterbody and mustard field, that have high radiation absorption capacity. The earth is excavated to expose the water beneath. The mound of excavated earth can be used to cover the shelter.

Functionalize Shelter in normal times
The shelter has been designed to make it perform as a communal facility, in this case, a school, in normal scenario. A school is a well-known communal facility where diverse group of people daily meet. It will enhance the possibility of local people’s engagement with it in disaster scenario.

Formation
The building has an aerodynamic form with less air surface and positioned in northwest to southeast direction over the site. 2 primary one-storied shelter masses are sandwiched in between 3 two-storied masses with tilted roofs. The ground floor is surrounded by earth mound. The tilted roof helps to make radionuclides falling in direction.

Technical information

Design Features

The Shelter
The shelter has 2 major features:
1. Surrounding landscape: In normal scenario, the landscape (waterbody, mustard green field, earth mound, roof garden) works as a binder between school and community. The nearby field and plaza for outdoor social gathering will generate a belongingness between the space and the community. In disaster scenario, the landscape works as a protector. The earth mound over ground creates natural boundary.
2. The building: The building ensures ground access for its users from 3 sides of the area. It has two types of shelters: primary and secondary. Primary shelter on the ground floor surrounded by earth mound is activated immediately after the disaster. Secondary shelter on the upper floor is activated after a few days when the air is less dangerous as a percentage of radionuclides precipitate over time.

Primary Shelter Protection Layers
The primary shelter has several layers of protection consisting of landscape components intertwined with building components, such as, water wells, earth on rooftop, deep overhangs, sunshades, radioprotective doors, thick concrete shear walls and roof slabs etc. It activates by closing 10 radioprotective doors. Light wells bring light during regular times. In disaster scenario, these shut off by closing radioprotective doors.

Primary Shelter Functions
Primary shelter functions include main shelter area (multipurpose hall) and service area. Services include toilet, kitchen, food storage, medical room etc. These can work in normal times also for the school. The machine room nearby is for backing up communication with the outer world.
Primary shelter can accommodate 1000 persons at full capacity.

Secondary Shelter Protection Layers
The secondary shelter is the circulation between classroom masses on the upper floors. In disaster times, these classrooms shut off and become protectors for the secondary shelter, same as the way mass protects the core. Mustard on tilted roof provide protection against radiation from roof contribution.

The School
The colorful landscape of the school will attract children. They will discover interesting spaces along the terrain. In normal times, primary shelter is used as a multipurpose hall. The radioprotective doors remain open. Light wells and water wells bring light inside the multipurpose hall. The circular ramp in the light well creates secondary circulation. The classrooms have natural light and ventilation with open strip windows.

Structure, Facade & Building Material
The building has a concrete shear wall structure. Concrete has high radiation absorption capacity. The facade is an envelope of textured concrete, which gives it a rough surface to deviate rays. Bamboo (local) shuttering is used in construction of the textured concrete surface. The radioprotective doors are made of lead encased in hard wood box panels. The windows and skylight in lightwell are made of radioprotective glass.

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