atw - International Journal for Nuclear Power | 10.2020

atw Vol. 65 (2020) | Issue 10 ı October
520
VAK Kahl
Operator: VAK GmbH (RWE 80 %, E.ON 20 %)
Milestones:
p Start of construction June 1958
60 YEARS OF NUCLEAR POWER IN GERMANY
| Fig. 3.
The control room of the VAK, 1961.
| Fig. 4.
Decommissioning of the VAK, reactor building, 2005.
| Fig. 5.
„Green field“ of the former VAK site, September 2010.
p First criticality 13 November 1960
p First grid connection 17 June 1961
p Cost of new build (1960) 34 Mio. DM (about 17 Mio. EUR,
without adjustment of inflation)
p Scheduled final shut-down 25 November 1985
Technical data:
Boiling water reactor with 16 MW electrical and 60 MW thermal capacity
p Net electricity supply to grid 2.1 billion (109) kWh
p Time availability 69,9 %
p Operation time 149,050 hours
p Number of fuel elements 361
p Number of operating periods 24
Employees:
At start-up about 75 permanent staff; during peak periods up to 123 employees
| Tab. 2.
VAK Kahl: Some facts about build and operation.
continuously keep pace with the
increasing safety requirements.
During its 25 years of operation,
the VAK proved to be a valuable
test facility (Figure 3). The most
important contributions to the testing
were made by the VAK in the areas
of material and fuel element testing.
The aim of the materials testing
was to find out how materials for reactor
pressure vessels change as a result
of permanent irradiation. For this
purpose, material samples were
brought close to the core and thus
exposed to a much higher radiation
power in defined operating times
than would be the case in actual use.
By means of these practical and
anticipatory irradiation programmes,
reliable statements on the suitability
of the individual materials could
be made after subsequent material
analyses – important findings for the
construction of the following nuclear
power plant generation.
As a test facility for fuel elements,
the VAK made probably the most
important contribution to the further
development of nuclear technology.
A total of 50 different types of fuel elements
were used and put through
their paces. For example, mixed oxide
fuel elements (MOX; nuclear fuel
made of uranium and plutonium)
were tested for the first time and fuel
elements for the later hot steam
reactor were tested. With the results
of these tests, basic calculation
methods for fuel element planning
and reactor operation could be
developed which are in principle still
used today.
The training of the required personnel
posed a particular challenge.
In Germany, there were no nuclear
power plants and also not yet the
simulators that are common today.
Therefore, the first team was sent to
the Vallecitos nuclear power plant,
USA, where they were deployed,
among others, in shift operation.
Thus, the basis was established which
was continuously expanded in the
first years with the help of American
consultants.
In order to maintain the experimental
character of the VAK beyond
the operating phase, RWE and
Bayern werk agreed in advance
that the VAK should be completely
dis mantled to the “greenfield site”
immediately after the end of operation
(Table 2). This dismantling
was intended to restore the original
condition of the terrain with the proof
that no inadmissible radioactivity is
still present on the plant site. At
that time, there was no comparable
decommissioning project worldwide,
so that here, too, new ground was
broken (Figure 4).
The overall decommissioning
was then carried out by a company
specialised in this field and the use
of heavy demolition machines. In
September 2010, this work was
completed on schedule with the
construction of the “greenfield site”
(Figure 5).
Author
Dipl.-Ing. Christopher Weßelmann
Editor in Chief, atw
60 Years of Nuclear Power in Germany
60 Years of Nuclear Power in Germany – Starting with First Criticality at the VAK, Kahl ı Christopher Weßelmann