CONSEQUENCES OF THE RUPTURE OF A PRESSURE TUBE OR OF A COMPLETE CHANNEL IN AN ORGEL-???? REACTOR. (Final Report)

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CONSEQUENCES OF THE RUPTURE OF A PRESSURE TUBE OR OF
A COMPLETE CHANNEL IN AN ORGEL-ΤΥΡΕ REACTOR - Final Report
by H. HOLTBECKER, M. MONTAGNANI and G. VERZELETTI
Commission of the European Communities
ORGEL Programme
Joint Nuclear Research Center - Ispra Establishment (Italy)
Engineering Department - Technology
Luxembourg, June 1970 - 208 Pages - 149 Figures - FB 275
This report considers the problems raised by the failure of an organic liquid
cooled channel in the heavy-water-moderated reactor ESSOR. It describes the
test rig, consisting of a 1 : 1 scale model of the vessel, connected to an organic-
liquid circuit capable of delivering, when the channel fails, the same throughput
of escaped coolant as would occur in actual operational failure.
The results are given of the variously obtained measurements of the mechanical
effects of the pressure waves generated by decompression of the coolant at
the moment of the channel failure, by evaporation of the organic liquid and
EUR 4493 e
CONSEQUENCES OF THE RUPTURE OF A PRESSURE TUBE OR OF
A COMPLETE CHANNEL IN AN ORGEL-ΤΥΡΕ REACTOR - Final Report
by H. HOLTBECKER, M. MONTAGNANI and G. VERZELETTI
Commission of the European Communities
ORGEL Programme
Joint Nuclear Research Center - Ispra Establishment (Italy)
Engineering Department - Technology
Luxembourg, June 1970 - 208 Pages - 149 Figures - FB 275
This report considers the problems raised by the failure of an organic liquid
cooled channel in the heavy-water-moderated reactor ESSOR. It describes the
test rig, consisting of a 1 : 1 scale model of the vessel, connected to an organic-
liquid circuit capable of delivering, when the channel fails, the same throughput
of escaped coolant as would occur in actual operational failure.
The results are given of the variously obtained measurements of the mechanical
effects of the pressure waves generated by decompression of the coolant at
the moment of the channel failure, by evaporation of the organic liquid and by the formation and collapse of steam bubbles created by the heat exchange
between the organic liquid and the water.
Thermal stress calculations are presented.
by the formation and collapse of steam bubbles created by the heat exchange
between the organic liquid and the water.
Thermal stress calculations are presented. ­ 3 ­
TABLE OF CONTENTS
gage
1 . INTRODUCTION 5
2. RIGCHARACTERISTICS5
3„ STATICANDDYNAMIC LOADS ON A CHANNEL DUE TORUPTUREOF
THEPRESSURETUBEΤ
3.1 BehaviouroftheSAP Tube at the Time of Explosion7
3*2 r of the Calandria Tube at the Moment of Rupture
10
of the Pressure Tube
3·2,1 Local Internal Damage to the Zr­2 Channel 14
3*3 Behaviour of the Channel StructuresattheBottom '4
3.3.1 Rubber Seals 14
3·3«2 ExpansionBellows'5
3.3»3 Travel­LimitingRods16
3.4 BehaviouroftheFuel Element17
4. BURSTOFBOTHPRESSURE AND CALANDRIA TUBES; LOADINGOF
CHANNELS,GUIDINGTUBES AND FUEL ELEMENT 19
4.1 Test Section Design19
4.2 Behaviour of Bursting Channel 19
4.3 r of the FuelElement20
4.4 Curve of Static PressureintheVessel During Organic
Injection 22
4*5 DynamicLoadsontheVessel25
4.6 FeasibilityofDrainingWater­Organic Mixtures from
Vessel26
4*7 LoadsonVesselInternals27
4.7.1 Decompressionofthe Organic Liquid 27
4.7.2 Temperature Rise in ChannelsAffectedbyOrganicJet29
4.7.3 Determination of the ThermalStressesonanInternally­
Insulated Channel Affected byanOrganicJet51
4.7.4 Channel Loads in the First TenthofaSecond Afterthe
Failure of a Neighbouring Channel55
4.7.5 Channel Loads Caused by Pressure Waves Generated by
Collapsing Vapour Bubbles 57
4.7.6 Effect ófthePresenceofReactor Channels onthe
PropagationofPressureWaves59
4.7.7 ApplicationoftheResults Obtained to Other Channel
Geometries 40
4.7.8 AccidentDetection40
ANNEXES42­82
REFERENCES84
LISTOFFIGURESACKNOWLEDGEMENTS
The test rig was designed and constructed in collaboration with the
firm of CIFA, Milan, and more especially with Messrs. G. Ausenda,
E. Cacciari, S. Balzanelli and C. Petronilli.
Mr. P. Golinelli, ably assisted by Mr. E. Soma, carried out the
machanical assembly of the test-section and the preparation of the
experiments.
Mr. V. Andrighetti and Mr. W. Schnabel were responsible for the
instrumentation of the test section.
The pressure measurements with standard and specially constructed
transducers were effected by Mr. E. Jorzik. - 5 -
1. INTRODUCTION *)
The rupture of a pressure tube is one of the severe accidents
which one has to consider in the hazards analysis of a pressure-tube-
type reactor. An experimental programme was undertaken to study the
rupture of a channel of an ORGEL (organic-cooled heavy-water-moderated)
reactor.
Although the geometry of the facility reproduces the core
lattice of the ESSOR reactcr, most of the results are also valid for
an ORGEL prototype reactor.
The present status of knowledge of these problems will be dis­
cussed as follows:
(a) dynamic and static loading of a channel caused by the failure of
the pressure tube;
(b) dynamic and static loading in the vessel and other channels
resulting from pressure waves and thermal stresses caused by the
failure of both the pressure tube and the calandria tube;
(c) fuel element loading during rupture of the channel.
As will be seen, not all of the problems quoted can be solved
by a direct quantitative calculation and therefore some of them require
experimental study.
The experiments carried out simulated the essential parts of
the actual geometry and coolant but light instead of heavy water was
used. (A detailed description of the plant is given in Ref. 1).
Annex 3 contains the diagrams of the measurements carried out, a table
of the results obtained and a brief description of each test.
2. RIG CHARACTERISTICS
The failure of an ORGEL channel was simulated by reproducing
the maximum pressure and temperature (30 atm, 420°C) and injecting
into the vessel, through the crack in the channel, the organic through­
put calculated from the ESSOR multiple circuit geometry (see Fig. 1).
*) Manuscript received on 16 January 1970 - 6 -
This calculation was performed on an analog computer, it being
assumed that the organic remains in the liquid phase. It will be
seen that in this case the calculating conditions increase the flow-
rate of the coolánü.
As the flowsheet shows (Fig. 2) the organic liquid passed from
the pump enters tank S2 (3 m capacity) and then the test channels,
after which it enters tank S3, which simulates the expansion tank
(2 nr capacity). Tank S2 permits the simulation of the two pumps by
means of a gas blanket which reproduces their driving head.
The design data for the circuit are:
pressure: 50 atn«
temperature: 450 C
The water circuit is connected to the vessel and to