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 2020-7

Back

Name:

Testing and Quality Control of Full Scale Bentonite Buffer Block Manufacturing

Writer:

Sjöblom, V., Rinta-Hiiro, V., Haapala, K.

Language:

English

Page count:

62

Summary:

This report is only published for Posiva's internal use.

The quality control work for the isostatically compressed buffer blocks are important part of the manufacturing process. The research for this working report was carried out during 2015–2016 and it was built upon the work done in 2008–2015. The objective of this work was to do quality control work for the isostatically compressed buffer blocks what are going to be used in the buffer block installation tests and FISST-project. During the production process, focus was on monitoring of block circumstances (temperature and relative humidity), block green body properties and machining of the blocks. The purpose of this work was to gain better understanding about the consequences of isostatic compression for the production of bentonite buffer components. In this study large isostatic full scale blocks were compressed at 17% water content with various compression pressures.

The machining work for the buffer blocks was successful, resulting in blocks with accurate dimensions and good quality surfaces. Also, lifting of the blocks using either lifting slings or the vacuum lifting device worked in a proper way. Turning the blocks upside down was very successful with the turntable used in welding work for handling large parts. The production of buffer blocks was time-consuming. Time for machining one block, including lifting, turning and packing of the block, was usually 3–4 working days. The machining itself took quite a long time due to the large amount to be machined. For example, for the R2 ring block, about 36% of the green body volume was to be turned. The reason for the high machining volumes was the test mould made for the fabrication tests of the first isostatic blocks. Because of test purpose, a reservation had been made in the mould for machining and sample drilling. The shrinkage of the green body and the uniformity of the shape were not known at the beginning, so an extra volume was reserved for the mould. In addition, the diameter of buffer blocks were larger, 1.70 m instead of the present diameter 1.65 m. Handling of the blocks, including lifting and turning, as well as proper packing after machining was time-consuming, because final equipment for block handling had not been purchased.

There were some challenges in keeping the desired RH in the surrounding air. The RH was sometimes lower than the target which was due to cold outdoor air. Humidity management was hampered by large production facilities where the machining area could not be compartmentalized. Some minor cracking was found from some of the blocks. Water was sprayed into the air with a high pressure pump to increase the humidity in the air. Increasing the humidity was also useful to remove bentonite dust from the air, which is important for the cleanliness and safety of the work. Along with the moisturizing system, a proper dust collection system is needed during the machining. The results of this work will be used in the development and design of the bentonite buffer manufacturing process and quality control.

Keywords:

Bentonite block, quality control, isostatic compression, factory-scale, bentonite pellets, buffer

File(s):


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