Пособие к учебнику технического английского языка «Nuclear English. Language Skills for a Globalizing Industry»

Sweden, France, and the USA, though in the USA there have been political delays. In Canada and the UK, deep disposal has been selected and the site selection process has commenced.

Vocabulary: waste packaging, repository, radionuclides, deep groundwater; nuclear waste management, disposal.

Mined repositories

The most widely proposed deep geological disposal concept is for a mined repository comprising tunnels or caverns into which packaged waste would be placed. In some cases the waste containers are then surrounded by a material such as cement or clay (usually bentonite) to provide another barrier (called buffer and/or backfill). The choice of waste container materials and design, as well as the buffer/backfill material varies depending on the type of waste to be contained and the nature of the host rock-type available.

Excavation of a deep underground repository using standard mining or civil engineering technology is limited to accessible locations, to rock units that are reasonably stable and without major groundwater flow, and to depths of between 250m and 1000m. The contents of the repository would be retrievable in the short term, and if desired, longerterm.

The Swedish proposed KBS-3 disposal concept. It uses a copper container with a steel insert to contain the spent fuel. After placement in the repository about 500 metres deep in the bedrock, the container would be surrounded by a bentonite clay buffer to provide a very high level of containment of the radioactivity in the spent fuel over a very long time period. In June 2009, the Swedish Nuclear Fuel and Waste Management Company (SKB) announced its decision to locate the repository at Östhammar (Forsmark).

Finland's repository programme is also based on the KBS-3 concept. Spent nuclear fuel packed in copper canisters will be embedded in the Olkiluoto bedrock at a depth of around 400 metres. The country's nuclear waste management company, Posiva Oy, expects the repository to begin disposal operations in 2023. Its construction was licensed in November 2015.

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The deposits of native (pure) copper in the world have proven that the copper used in the final disposal container can remain unchanged inside the bedrock for extremely long periods, if the geochemical conditions are appropriate (low levels of groundwater flow). The findings of ancient copper tools, many thousands of years old, also demonstrate the long-term corrosion resistance of copper, making it a credible container material for long-term radioactive waste storage.

Vocabulary: packaged waste, waste container, barrier material; excavation of a repository, retrievable contents of a repository; copper container, high level of containment; groundwater flow, corrosion resistance, radioactive waste storage, long term storage.

Deep boreholes

As well as mined repositories, which have been the focus of most international efforts so far, deep borehole disposal has been considered as an option for geological isolation for many years, including original evaluations by the US National Academy of Sciences in 1957 and more recent conceptual evaluations. In contrast to recent thinking on mined repositories, the contents would not be retrievable.

The concept consists of drilling a borehole into basement rock to a depth of up to about 5000 metres, emplacing waste canisters containing used nuclear fuel or vitrified radioactive waste from reprocessing in the lower 2000 metres of the borehole, and sealing the upper 3000 metres of the borehole with materials such as bentonite, asphalt or concrete. The disposal zone of a single borehole could thus contain 400 steel canisters each 5 metres long and one-third to half a metre in diameter. The waste containers would be separated from each other by a layer of bentonite or cement.

Boreholes can be readily drilled offshore (as described in the section below on sub seabed disposal) as well as onshore in both crystalline and sedimentary host rocks. This capability significantly expands the range of locations that can be considered for the disposal of radioactive waste.

Deep borehole concepts have been developed (but not implemented) in several countries, including Denmark, Sweden, Switzerland, and the USA. Compared with deep geological disposal in a mined underground repository, placement in deep boreholes is considered to be more

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expensive for large volumes of waste. This option was abandoned in countries such as Sweden, Finland, and the USA, largely on economic grounds. The borehole concept remains an attractive proposition for the disposal of smaller waste forms including sealed radioactive sources from medical and industrial applications.

An October 2014 US Department of Energy (DOE) report said:

“Preliminary evaluations of deep borehole disposal indicate a high potential for robust isolation of the waste, and the concept could offer a pathway for earlier disposal of some wastes than might be possible in a mined repository.” In January 2016 the DOE commissioned a team led by Battelle to drill a 4880-metre test borehole into crystalline basement rock in North Dakota.

Vocabulary: deep borehole disposal, waste canisters, vitrified radioactive waste; large volumes of waste, smaller waste forms.

Mined repositories – development examples

Boom clay & Opalinus clay, Europe

The Belgian disposal concept proposes that spent fuel and HLW is placed in high integrity steel containers and then emplaced in excavated tunnels 230 metres deep within a ductile (self-sealing) clay – the Boom clay. The very low permeability of the clay leads to virtually no groundwater flow over long time periods. Waste would be backfilled with excavated clay or, alternatively, could be emplaced into unlined secondary tunnels where the clay would be allowed to 'creep' into contact with the waste containers. Similar systems have been proposed in the Netherlands and, using less plastic clays, in France and Switzerland (Opalinus clay). Clay is generally suitable for heatgenerating HLW.

The French radioactive waste disposal agency, Andra, is designing a deep geological repository in clays at Bure in eastern France. This will be for disposal of vitrified HLW and long-lived ILW. The repository is designed to operate at up to 90ºC, which is likely to be reached about 20 years after emplacement.

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Vocabulary: HLW (high-level waste), high integrity steel containers, ductile (plastic) clay, low permeability, vitrified high-level waste, longlived ILW (intermediate level waste).

Yucca Mountain, USA

At the end of 1987, the Nuclear Waste Policy Act was amended to designate Yucca Mountain, located in the remote Nevada desert, as the sole US national repository for spent fuel and HLW from nuclear power and military defence programs. An application by the US DOE to construct the repository was submitted in June 2008.

The repository would exist 300 metres underground in an unsaturated layer of welded volcanic tuff rock. Waste would be stored in highly corrosion-resistant double-shelled metal containers, with the outer layer made of a highly corrosion-resistant metal alloy, and a structurally strong inner layer of stainless steel. Since the geological formation is essentially dry, it would not be backfilled but left open to some air circulation. Drip shields made of corrosion-resistant titanium would cover the waste containers to divert possible future water percolation and provide protection from possible falling rock or debris. Containment relies on the extremely low water table, which lies approximately 300 metres below the repository, and the long-term durability of the engineered barriers.

The project has experienced many delays since its inception and following the 2009 presidential election the Barack Obama administration decided to cancel it. However, in June 2010, the Nuclear Regulatory Commission's Atomic Safety and Licensing Board (ASLB) rejected the DOE's motion to withdraw the licence application, and in August 2013 the federal Appeals Court ordered the NRC to resume its review of the DOE's application for a licence to construct and operate the Yucca Mountain repository. The final volumes of the NRC‟s safety evaluation report were published early in 2015, which contain the agency's technical review of safety of the repository. In May 2016, the NRC released its final supplement to the US DOE's environmental impact statement on the proposed Yucca repository. Both the environmental impact assessment and the NRC's experts established that the repository design would prove safe for one million years.

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Vocabulary: unsaturated layer of rock, highly corrosion-resistant metal containers, double-shelled metal containers, inner layer of stainless steel, corrosion-resistant titanium, engineered barriers; safety evaluation report, environmental impact assessment.

Disposal in layered salt strata or domes

Geological salt environments have a very low rate (perhaps even an absence) of groundwater flow and feature gradual self-sealing of the excavations due to creep of the salt, which is plastic. Salt is generally suitable for heat-generating HLW.

The Waste Isolation Pilot Plant in New Mexico for defence transuranic wastes (long-lived ILW) has been operational since 1999. For this repository natural rock salt is excavated from a Permian layer several metres thick, between other types of rock, 650 metres below ground level. The wastes placed in these excavations contain large volumes of long-lived ILW, usually in steel drums. These are then placed on pallets and stowed in excavated rooms or caverns. The salt is plastic and will eventually seal the wastes and isolate them permanently. Containment of the radionuclides in the wasteform mostly relies on the almost complete absence of water flow in the salt. To July 2013, there had been 11,500 road shipments of wastes to WIPP from 12 DOE sites, and 87,500 cubic metres of ILW disposed.

Following an exhaustive site selection process the state government of Lower Saxony in 1977 declared the salt dome at Gorleben to be the location for a German national centre for disposal of radioactive wastes. Following a new law in early 2017, Gorleben is now considered one possible site for geological disposal of HLW. The site could be available as a final repository from 2025, with a decision to be made about 2019.

Some €1.5 billion was spent over 1979 to 2000 researching the site.

Work then stopped due to political edict, but resumption of excavation was approved following a change of government in 2009.

Vocabulary: geological salt with low level of groundwater flow, transuranic waste, long-lived ILW (intermediate level waste), steel drums, radionuclides.

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Nirex Phased Disposal Concept, UK

The UK's Nirex Phased Disposal Concept (or Phased Geological Disposal Concept) has been developed for relatively large volumes of ILW and LLW, usually cemented into stainless steel containers. These containers would be emplaced into a repository in a host rock environment below the water table. The waste would be monitored and remain retrievable and the groundwater managed to prevent contact with the wastes, until such a time that the repository is sealed. When this happens, the waste will be surrounded (backfilled) by specially formulated cement and the repository allowed to resaturate. The cement would provide a long-lasting alkaline environment that contributes to containment of the waste by preventing many radionuclides from dissolving in the groundwater. Similar cement-based schemes for ILW disposal have been proposed in France, Japan, Sweden and Switzerland.

Vocabulary: large volumes of ILW and LLW (low-level waste), steel containers, specially formulated cement, to be allowed to resaturate, long-lasting alkaline environment.

Unit 9

NUCLEAR APPLICATIONS Vocabulary activator on the topic.

Match the term and its definition. Radioisotope, sealed source, diagnosis, iodine, ionizing, cobalt, radiopharmacy, radiopharmacist.

Encapsulated radioactive material;

Preparation of radioactive compounds used for diagnosis and radiotherapy;

Determining the cause of an illness;

Chemical element, the radioisotope iodine-131 is used to treat thyroid disease;

Of radiation, capable of breaking chemical bonds in the matter through which it passes;

A healthcare professional who is considered an expert in cancer medications.

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Chemical element – radioactive cobalt-60 was often used in radiotherapy;

A naturally occurring or artificially created radioactive isotope of a chemical element: used in medical therapy, biological research, etc

PART ONE

Study the text about Magnetic resonance imaging and fill in the gaps with the given words for each passage.

Magnetic Resonance Imaging (MRI) at National Institute of Biomedical Imaging and Bioengineering.

(available at www. nibib.nih.gov, accessed 03.2017) What is MRI?

non-invasive (done without cutting the body), detection, rotational, tissues (materials which form part of the body)

MRI is a _______ imaging technology that produces three dimensional detailed anatomical images without the use of damaging radiation. It is often used for disease __________, diagnosis, and treatment monitoring. It is based on sophisticated technology that excites and detects the change in the direction of the ________ axis of protons found in the water that makes up living ________.

How does MRI work?

protons, equilibrium, sensors, realign (align again, arrange in a line), molecules

MRIs employ powerful magnets which produce a strong magnetic field that forces ______ in the body to align with that field. When a radiofrequency current is then pulsed through the patient, the protons are stimulated, and spin out of ________, straining against the pull of the magnetic field. When the radiofrequency field is turned off, the MRI

________ are able to detect the energy released as the protons _____

with the magnetic field. The time it takes for the protons to realign with the magnetic field, as well as the amount of energy released, changes depending on the environment and the chemical nature of the ______.

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Physicians are able to tell the difference between various types of tissues based on these magnetic properties.

How is an MRI image obtained?

blur (make smth difficult to see, unclear), Gadolinium (Gd), intravenously (into a vein), brighter

To obtain an MRI image, a patient is placed inside a large magnet and must remain very still during the imaging process in order not to

______ the image. Contrast agents (often containing the element

_________) may be given to a patient ________ before or during the MRI to increase the speed at which protons realign with the magnetic field. The faster the protons realign, the _______ the image.

What is MRI used for?

Ionizing, knee and shoulder, differentiate, frequent, x-rays

MRI scanners are particularly well suited to image the nonbony parts or soft tissues of the body. They differ from computed tomography (CT), in that they do not use the damaging _________ radiation of x- rays. The brain, spinal cord and nerves, as well as muscles are seen much more clearly with MRI than with regular x-rays and CT; for this reason MRI is often used to image _______ injuries.

In the brain, MRI can ________ between white matter and grey matter and can also be used to diagnose tumors. As MRI does not use

______ or other radiation, it is the imaging modality of choice when

______ imaging is required for diagnosis or therapy, especially in the brain. However, MRI is more expensive than x-ray imaging or CT scanning.

Are there risks?

Emit, exerts, containing, decibels, ear-protection precaution, tolerate

Although MRI does not ______ the damage that is found in x-ray and CT imaging, it does employ a strong magnetic field. The magnetic field extends beyond the machine and _____ very powerful forces on objects of iron, some steels, and other magnetizable objects. It is strong enough to fling a wheelchair across the room.

When having an MRI scan, the following should be taken into consideration:

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•People with implants, particularly those ________ iron, should not enter an MRI machine.

•Loud noise commonly referred to as clicking and beeping, as well as sound intensity up to 120 _______ in certain MR scanners, may require special ________.

• MRI scans should be avoided especially in the first trimester of pregnancy.

•People with even mild claustrophobia may find it difficult to

______ long scan times inside the machine.

Fill in the gaps with the given prepositions: to, from, for, for, on, off, with, in, to, from.

1.Some patients may require special care in case of loud noise commonly referred ___ as clicking and beeping.

2.There is a risk of a twitching sensation. It sometimes results ____

the rapidly switched fields in the MRI.

3.MRI is chosen when frequent imaging is required ____ diagnosis or therapy, especially in the brain.

4.Researchers are developing an optical tracking system which could make MRI a viable option for many patients who are unable to remain still for the exam and reduce the amount of anesthesia used ____

MR exams.

5.MRI is based ____ sophisticated technology which produces a strong magnetic field.

6.When the radiofrequency field is turned _____, the MRI sensors are able to detect the energy released.

7.MRIs employ powerful magnets which produce a strong magnetic field that forces protons in the body to align ____ that field.

8.The Magnetic Resonance Elastography (MRE) device is safe and comfortable for the patient. Since MRE is able to recognize very slight differences ___ tissue density, there is the potential that it could also be used to detect cancer.

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9.Contrast agents may be given ____ a patient intravenously before or during the MRI to increase the speed at which protons realign with the magnetic field.

10.MRI scanners differ ____ computed tomography (CT), in that they do not use the damaging ionizing radiation of x-rays.

(Prompt for prepositions: refer to, result from, required for, used for, based on, turned off, align with, differences in, give to, differ from.)

Pay attention to the following speech patterns.

1.The faster the protons realign, the brighter the image.

2.A patient must remain very still during the imaging process in order not to blur the image.

Make up several phrases to practice these patterns.

You are given several passages about MRI technology. Find the terms which mean:

1. A medical doctor specially trained in radiology, the branch of medicine concerned with radioactive substances and their use for the diagnosis and treatment of disease.

The images from an MRI examination are called slices, because they are acquired in very small (millimeter-size) sections of the body. The image slices are displayed on a computer monitor for viewing or printed as a film. A specialist called a radiologist interprets the images produced during the MRI examination.

2. Fear of small, enclosed spaces.

Newer MRI scanners have shorter patient openings that allow the patient's head to remain outside the machine during body scans. Open MRI scanners are available with columns and open sides to alleviate claustrophobia.

3. An imaging technique in which cross-sectional x-rays of the body are compiled to create a three-dimensional image of the body's internal structures.

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