Environmental Engineering Reference
In-Depth Information
accompanied by radiation leaks and creation of conditions for the initiation
of an accident with nuclear consequences (in the case of fracture of two
or more pipes).
Adoption of the full volume of the guidelines excludes the possibility
of pipe rupture during operation. The probability of pipe rupture becomes
zero after complete implementation of the guidelines. Some results of
evaluating the reliability of steam generator pipes in relation to measures
taken are shown in Fig. 9.35. It can be seen that the set of events of the
last variant (chemical washing (CW), hydraulic tests (HT) at a pressure of
240 atm, the pneumo-hydraulic method for inspecting density (PHI), and
plugging of leaking HETs ensures that the steam generator tubes cannot
fail even in the most severe conditions - in the case of a pressure drop
in the SG secondary circuit (e.g. as a result of a steam generator rupture).
Increasing the reliability of eddy current testing. Following the
recommendations of the guidelines full, the reliability of ECT doubles
(curves in Fig. 9.38).
Increasing the detectability of the pneumo-hydraulic method for
monitoring the density and integrity of the steam generator pipe. The
detectability of the pneumo-hydraulic method for monitoring the density and
integrity of the steam generator pipes after implementation of the guidelines
in full increased from 50% to 100% (points in Fig. 9.38).
Reduced cost of operation of steam generator with damaged tubes. As
a result of application of the guidelines, other results were also achieved
that have both technical and economic importance to the plant, namely:
1) increase in power generation by eliminating unplanned shutdowns of
units because of leaks between in SG circuits, as well as by reducing the
timing of planned maintenance work in which the eddy current testing of
steam generator pipes was in the 'critical path' of these works;
2) reduction in maintenance costs of steam generators due to the fact that
the volume of eddy current testing and plugging of leaky pipes is reduced.
￿ ￿ ￿ ￿ ￿
After
After
Balakovo plant
unit 2, 1996
Novovoronezh
plant
unit 3, 2003
Before
Before
Operating periods
9.37 Increase the number of leaky pipes in a steam generator
prior to applying the system concept and after. 
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