Databank

Databank

Posiva publishes Working Reports and Posiva Reports. From the year 2006 nearly all the reports have been published on our webpage and they can be found in the databank. In the databank you can also find our Annual Reviews and some other publications as well. You can also find print-quality pictures and useful links in the databank.

Recent publications


Workreport 2008-56

Back

Name:

Backfilling Techniques and Materials in Underground Excavations: Potential Alternative Backfill Materials in Use in Posiva’s Spent Fuel Repository Concept

Writer:

Dixon, D. A. & Keto, P.

Language:

English

Page count:

74

Summary:

A variety of geologic media options have been proposed as being suitable for safely and permanently disposing of spent nuclear fuel or fuel reprocessing wastes.  In Finland the concept selected is construction of a deep repository in crystalline rock (Posiva 1999, 2006; SKB 1999), likely at the Olkiluoto site (Posiva 2006).  Should that site prove suitable, excavation of tunnels and several vertical shafts will be necessary.  These excavations will need to be backfilled and sealed as emplacement operations are completed and eventually all of the openings will need to be backfilled and sealed. Clay-based materials were selected after extensive review of materials options and the potential for practical implementation in a repository and work over a 30+ year period has led to the development of a number of workable clay-based backfilling options, although discussion persists as to the most suitable clay materials and placement technologies to use.  

As part of the continuous process of re-evaluating backfilling options in order to provide the best options possible, placement methods and materials that have been given less attention have been revisited.  Primary among options that were and continue to be evaluated as a potential backfill are cementitious materials. These materials were included in the list of candidate materials initially screened in the late 1970’s for use in repository backfilling. Conventional cement-based materials were quickly identified as having some serious technical limitations with respect their ability to fulfil the identified requirements of backfill. Concerns related to their ability to achieve the performance criteria defined for backfill resulted in their exclusion from large-scale use as backfill in a repository. Development of new, less chemically aggressive cementitious materials and installation technologies has resulted in their re-evaluation. Concrete and cementitious materials have and are being developed that have chemical, durability and mechanical properties that should allow their use in limited quantities in a repository (e.g. grouts, shotcrete or concrete plugs/seals). Widespread use of cemented backfill materials is still not a viable option for backfilling of Posiva’s repository although some of the technologies developed for materials placement in the mining industry have potential for repository application.

Extensive work has been done in order to identify a range of potentially suitable clay-based backfilling materials and technologies that could be used to install them in a repository environment. As a result of these efforts a suite of materials and technologies are available for backfilling of repository openings and although many have not yet been demonstrated at full-scale in an underground environment there is considerable confidence that one, or more of these options will prove suitable.

Keywords:

spent nuclear fuel, disposal, backfill, assessment, concept

File(s):

Backfilling Techniques and Materials in Underground Excavations: Potential Alternative Backfill Materials in Use in Posiva's Spent Fuel Repository Concept (pdf) (1.7 MB)


Back


Share article:
This website stores cookies on your computer. These cookies are used to improve our website and provide more personalised services to you.
Close

Cookies

To make this site work properly, we sometimes place small data files called cookies on your device. Most big websites do this too.

1. What are cookies?

A cookie is a small text file that a website saves on your computer or mobile device when you visit the site. It enables the website to remember your actions and preferences (such as login, language, font size and other display preferences) over a period of time, so you don’t have to keep re-entering them whenever you come back to the site or browse from one page to another.

2. How do we use cookies?

A number of our pages use cookies to remember your actions and preferences (such as login, language, font size and other display preferences.)

Also, some videos embedded in our pages use a cookie to anonymously gather statistics on how you got there and what videos you visited.

Enabling these cookies is not strictly necessary for the website to work but it will provide you with a better browsing experience. You can delete or block these cookies, but if you do that some features of this site may not work as intended.

The cookie-related information is not used to identify you personally and the pattern data is fully under our control. These cookies are not used for any purpose other than those described here.

3. How to control cookies

You can control and/or delete cookies as you wish – for details, see aboutcookies.org. You can delete all cookies that are already on your computer and you can set most browsers to prevent them from being placed. If you do this, however, you may have to manually adjust some preferences every time you visit a site and some services and functionalities may not work.

Close