| ABSTRACT: | LEAK TESTING OF PRODUCTS UNDER TRANSIENT CONDITION.
I.I.Loktev1, V.V.Rozhkov1, A.B.Aleksandrov1, I.A.Tichomirov2
1OJC “NCCP”,Russia; 2TPU, Russia
Leak-testing of a nuclear fuel elements must be carried out with high sensitivity, a leakage norm
is in region of 10-10m3Pa/s. It is better to do it in static mode of operation of test device or with using
accumulation of a probe gas.
The static mode testing begins after evacuation of test chamber, engaging of leak detector and
having stationary flowing in test system. At this moment the leak detector shows true leakage of the parts
under testing.
But transition to static state takes too much time for test system with a chamber of big volume. It
can be deduced a formula for leak flow, which the detector shows during transient into static state of test
system:
,
where QLT - leakage, shown by test system,
QN - normal leakage of tested parts,
S0 - speed of pumping of leak detector,
V - volume of test chamber,
Pl - limit of pressure of detector pump.
It can be proposed three way of leak-testing in transient regime with using this expression:
1- at quasistatic regime of testing, when they execute reading of leak detector a 0,9T, where T -
transient time, (t<0,9T), condition of quality control is QLT ?QN.
2 - at current transient regime, when they execute reading of leak detector at any time t, condition
of quality control is:
3- at transient regime with threshold, when they execute reading of leak detector after time
interval of Ttest , condition of quality control is:
Conclusion.
A way of leak-testing with accumulation of probe gas, which is under consideration at the report
also, and three mentioned methods are ways of acceleration of transient and increasing of sensitivity of
testing.
Mentioned ways of leak-testing were approved during developing of leakage control process of
nuclear fuel for atomic power plant.
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