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UNITED STATES Af ATOMIC ENERGY COMMISSION
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WASHINGTON. D.C. 20545
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April 25, 1972 Docket No. 50-265 Dr. Chester P. Siess Chairman, Advisory Comittee on Reactor Safeguards U. S. Atomic Energy Cammission Washington, D. C.
20545
Dear Dr. Siess:
Sixteen (16) copies of the following are transmitted for the Comittee's information:
'WX from Commonwealth Edison Company dated April 24, 1972, reporting an abnormal occurrence when the heat tracing on the pump section piping on the standby liquid control system for Quad Cities Nuclear Power Station Unit 2 wat discovered to be inoperable 1
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Sincerely, 5
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PDR Assistant Director THOMA%S PDR 40 for Reactor Operations Division of Reactor Licensing
Enclosures:
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SOFF1MNT NO.153 CATEGORY B 3
.Mk Omad Cities April 24, 1972 M
Details on the spent fuel cask enerzy absorbi g Jytejia are provided t
in a Commonwealth Edison letter dated April 17, 1972.- A 3' thick ACRS section of aluminum honeycomb is to be installed in _ the area when the cask is t'aised and louered, and an 8" thick section in - the ' area where the fuel handling operstions take place.
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No ACRS action is recommended.
This item should be incorporated in your set of project documents to maintain an up-to-date description of the plant, organization, procedurec, etc.
IM11 Chance No. I to the toch specs dated April 19, 1972 permits lowerinc 6
the turbine-control-oi1~ pressure scram a c:: pMut from 1100 psig to
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900 pig. This is necessary to reduce the frequency cf spur h scrams during startup, and was previously approved for Dresden 2 and 3.
'I No ACES action is reconssended.
This item should be incorporated in your set of project documents to maintain an up-to-date description of the plant, orgariaation, I-procedures, etc.
l 11M11 Failure of the RCIC system to operate on test is reported in a Common-wealth letter dated April 19, 1972. (lausediate testing of EPCI system showed satisfactory operation.) The problem was traced to a faulty transducer identified as the EGE ACTUATOR. After replacenant the RCIC system operated satisfactorily.
I No ACES action is recommended. The enclosed material may be discarded after your review.
IDGi Abnormal Occurret.ce 2-72-2 was nported by TWK on April 24. The problem was the inoperability of the best tracitut on the standby liesW centrol system for Unit 2.
No other details are provided. A more thsesugh written report presumably will follow.
FILE: Quad Cities Proj. & Cat B No ACRS action is recommended. The enclosed natarial may be discarded Files after your review.
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ANS 7.60 PROPOSED STANDARD FOR LEAKAGE-RATE TESTING OF CONTAINMENT STRUCTURES G
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Standards Committee Revised for Submittal to N/45
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111; AMERICAN NUCLEAR SOCIETY It is the policy and practice'of.'the Standards Committee -
of the American Nuclear Society through its' subcommittees to formulate and promulr, ate' proposed standards for the nuclear-
, industry.
This stanctard was prepared on' the consensus principle land is based'on the experience and.. knowledge available at the time.
This, standard is intended as a guide to aid the manufacturer, the consumer,.and the general ~public.
The existence of'a standard does not in any respect preclude any party from. manufacturing, selling, or using' products, processes, or procedures not con-forming to the standard.-
This standard is subject to periodic review and reaffirmation or revision.
The existence of this standard does not relieve its user from the_ requirement that he exercise good judgment in its application,.and that he provide himself with technical competence commensurate to his. activities, nor does complianc.s with ANS Standards assure acceptability to federal, state, or local authorities.
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FOREWORD
.(This fareword is not a part of the proposed standard.)
This proposed standard was initially prepared by Evan F.
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Wilson of the Allis-Chalmers Manufacturing Company, and on his retirement, by Stephen S. Bacharach, Consultant, in their capacities as members of Subcommittee ANS-7, Reactor Components, of the American. Nuclear Society Standards Committee..Dua work was initiated early in 1959, and the standard has undergone some 13 or more reviews and revisions.. Corrections.and additions were incorporated into six formal revisions, of which this is the latest.
Representatives of more 'than 20 companies involved in nuclear'research and development and other companies involved in the fabrication and construction of the containment vessels participated in the reviews of this standard.
The following are presently members of Subcommittee ANS-7:
S. S. Bacharach, Chairman, Consultant H. Hopkinr, Secretary, Gulf-General Atomic E. S. Brown, Idaho Nuclear Corporation D. D. Cannon, Oak Ridge National Laboratory A. W. Flynn, Ebasco Services, Inc.
F. W. Gettler, Gibbs and Hill, Inc.
K. C. Hoffman, Brookhaven National' Laboratory A. B. Holt, U. S. Atomic Energy Commission W.-C. Lip'nski, Argohne National Laboratory J. F. Matousek, Argonne National Laboratory R. K. Robinson, Douglas United Nuclear, Inc.
J. C. Rusc, General Electric Company A. W. Savolainen, Oak Ridge National _ Laboratory l
R. P. Schmitz, Bechtel Corporation C. Z. Serpan, Jr., Naval Research Company J. H. Taylor, Babcock & Wilcox Company D. E. Thorn, Westinghouse Atomic Power Division The standard was further considered by the ANS memberdhip as a whole by publication for comments as Nuclear Engineering Bulletin, Vol. 2, December 1964.
It was balloted on by the ANS Stanaards Commi ttee and finally approved on June 14, 1967.
Subsequent comments by members of USASI Subcommittee N 45 resulted in the i
present. issue dated Oct. 15, 1968.
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vii CONTENTS Section Page 1.
Pu rp o s e an d S c op e.......................................
1 1.1 Purpose............................................
1 1.2 Scope..............................................
1 2.
Conjunctive. Standards...................................
1 2.1 ~ Conditions of Applicability........................
1 2.2 Conjunctive Standards..............................
1 3
Definitions and Descriptions.of Terms...................
2 3.1 Containment Structure..............................
2 32 Leak.....................................&.........
2 33 Leakage............................................
2 3.4 Leakage Rate.......................................
'2 35 Maximum Allowable Leakage Rate.....................
2 l -
4.
Preliminaries to' Leakage-Rate Testing...................
2 4.1 Sequence of Tests..................................
2 4.2 Pressure Tests for Strength........................
3 i
l 43 Integral Pneumatic Leak-Detection Tests............
3
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4.4 Local Leak-Detection Tests.........................
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4.5 General Preparations for Test Pressurizing.........
3 4.6 Time Schedu. ling of the Leakage-Rate Test...........
4 1
5 Leakage-Rate Test Methods...............................
4 5.1 Applicable Test Methods............................
4 52 Description of Methods.............................
4 6.
Te s t Equipmen t and Facilities...........................
4 6.1 Pressurizing Facilities...........................
4 1
6.2 Temperature Measurements..k.........................
4
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6.3 Pressure Measurements..............................
-5 6.4 Instrument Accuracies..............................
l 7.
Test Procedures.........................'................
5 7.1 The Absolute Method................................
5 7.2 The Reference Vessel Method........................
5 73 Pressurizing.......................................
5 7.4 Temperature Measurements...........................
6 75 Personnel Access to Pressurized Containment Structures........................................
6 1
7.6 Period of Test.....................................
6 I
7.7 Humidity Monitoring................................
6 7.8 Recording of Data..................................
7 79 Computation of Leakage-Rate - General..............
7 7.10 Computation of Leakage-Rate - The Absolute Method..
7 7.11 Computation of Leakage-Rate - The Reference-Vessel Method............................................
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Appendix A.
Local Leak-Testing Procedures.................
13 A.1 Applic ability of Local Leak Tes ts.................
13 i
A.2 Water Submersion Test.............................
13 i
A.3 vacuum Test.......................................
13 I
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viii.
Section Page A.4 -Air-Ammonin Test...................................
13
'A 5 Halogen Sniffer Test...............................
13 A.6 Ultrasonic Leak Detector...........................
14
-Appendix.B. Derivation of Formulas for Containment Structure Leakage Rates..................................
15
-B.l.
Definition of: Symbols..............................
15 B.2 Determination.of Leakage Rate - The Absolute Method.15 B.3 Determination:of' Leakage Rate - The Reference-Vessel Method............................................
16 Appendix C.
Suggested Method for Verification of Leakage.
Test Accuracy................................
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PROPOSED STANDARD FOR LEAKAGE-RATE TESTING OF CONTAINMENT STRUCTURES FOR NUCLEAR REACTORS
- 1. Purpose and Scope 1.1 Purpose.
The purpose of this standard is to specify uniform methods for determining the ability of a reactor container to retain, within the limits of permissible leakage rates, any gases, vapors, liquid, or other fluid materials that would be of a hazardous nature if not contained and which might be present in the containment structure as a result of an energy release, rupture, or leak in the nuclear reactor components or accessories.
The need for restriction of leakage from the containment structure is based on the maintenance of public health and safety.
1.2 Scope.
The provisions of this standard specify the practices and ' test requirements for the quantitative determination of leak-age rates of containment structures for the housing of operating The provisions apply to containment structures nuclear reactors, for nuclear power, test, research, and training reactors, wherever a gas-tight containment structure is specified as a condition for operation.
- 2. Conjunctive Standards 2.1 Conditions of Applicability.
This standard shall be applied in conjunction with such other standards and codes as are specified in the containment construction contract.
Acceptance of a con-tainment structure with respect to the requirements of this standard shall not relieve the supplier of responsibility for compliance with other codes specified for design, fabrication, construction, inspection, proof testing, and maintenance.
Standardsorcodeswhichmaybe 2.2 Conjunctive Standards.
conjunctive to the present standard are the following:
2.2.1 ASME Boiler and Pressure Vessel Cope, Section 3, aules for Construction of Nuclear Pressure Vessels.
2.2.2 ASME Boiler and Pressure Vessel Code, Section 2, Material Specifications.
2.2.3 ASME Boiler and Pressure Vessel Code, Case Interpretations.
2.2.4 USA Standard B31.1.0 Code for Pressure Piping.
2.2.5 USA Standard A57.1-1952: American Institute of Steel Construction, Specifications for the Design, Fabrication, and Erection of Structural Steel for Buildings.
2.2.6 USA Standard A58.1-1955: Building Code Requirements for Minimum Design Loads in Buildings and Other Structures.
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2.2.7 USA Standard A89 1-1964: Building Code Requirements for Reinforced Concrete. (ACI-318-63) 2.2.8 National Fire Codes, National Fire Protection Association.
2.2 9 American Petroleum Institute, Recommended Rules for the Design and Construction of Large, Welded, Low-Pressure Storage Tanks.
2.2.10 USA Standard N6.2-1965: Steel Containment Structures.
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Definitions and Descriptions of Terras 3 1 Containment Struc ture.
A containment structure within the meaning of this standard shall be an erected building, vessel, or underground location that provides a housing for elements of the reactor system, including certain of the primary vessels, components, and accessories.
The function of the containment structure shall be the emergency and secondary retention of radioactive materials in the event of their accidental release from the reactor vessel or system into the containment structure.
q 3 2 Leak.
A leak, in the context of this standard, shall constitute an opening, however minute, that allows the passage of a fluid and which is detectable by the means and methods specified herein for leak detection or leakage measurement.
3.3 Leakage.
Leakage shall be interpreted as the measurable quantity of fluid escaping from a leak.
For the purposes of this standard, air shall be used as the reference fluid.
i 3.4 Leakage Rate.
Leakage rate is that leakage experienced during a specified period of time.
For the purposes of this standard, leakage rate shall be reported as the percentage by weight of the original content of air at the leakage-rate test pressure that could escape to the outside atmosphere during a 24-hr. test period.
The leakage rate shall be that experienced at the outside atmosphere and containment structure air conditions prevailing during the period of leakage-rate testing.
3.5 Maximum Allowable Leakage Rate.
The maximum allowable leakage rate governing the acceptability of the containment structure by those responsible for its reliability shall be that stipulated in the specification for the individual containment structure.
4.
Preliminaries to Leakage-Rate Testing 4.1 Sequence of Tests.
Initial construction proof leakage-rate testing or testing af ter major repairs requiring strength welding should be conducted after the inspection and testing of welded joints, penetrations, and mechanical closures; completion of repair measures for minimizing of leakage; and completion of any required containment structure pressure tests for strength.
Where the containment structure is to be subsequently covered with concrete or will other-wise be inaccessible for direct examination, particular care should L__-__________
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3 be given to inspection of these areas prior to such coverage.
Integral or local leak detection should preferably precede leakage-rate tests.
For retesting, en initial record test shall be conducted at time periods and pressures established by the responsible regulatory agency, before any preparatory repairs are made.
This will disclose the normal state of repairs of the containment structure.
If the results of this test prove unsatisfactory, local and integral tests may be performed and any necessary work done to bring the leakage rate within the specified limits.
A proof leakage-rate test shall then be msde to demonstrate that the maximum allowable leakage rate is not exceeded.
4.2 Pressure Tests for Strength.
Initial construction hydrostatic or pneumatic pressure tests to determine whether the containment structure complies with specified strength and design requirements, or pressure test required after major repairs requiring strength welding, shall precede leakage-rate testing.
Also, the results of pressure tests shall meet the contractual specifications before leakage-rate tests are initiated.
4.3 Integral Pneumatic Leak-Detection Tests.
The detection of individual leak locations, preliminary to leakage-rate testing, may be affected by local or integral pressurizing of the containment structure or both and the use of soap solution to provide air-bubble indications on exterior surfaces or other leak detecting methods of equal or greater sensitivity.
4.4 Local Leak-Detection Tests.
Localized pressure tests may be advantageously employed in some circumstances where the part or area is especially susceptible to leakage or it is wished to employ higher pressures than in the intergral-pressurizing detection test.
Local leak-detection methods may incilude the pneumatic soap-bubble test, vacuum testing, air-ammonia and halogen sniffer tests, or other tests developed for special examinations.
Local tests are particularly suitable for inspection of equipment prior to installation in the container and for inspection of moderately small but complex assemblies where leaks are difficult to locate and where the leakage-rate is especially slow.
Descriptions of local leak-detection methods are given in Appendix A.
If the local leak-detection test is carried out with internal pressurizing, a j
pressure of at least 5 psig shall be used if the design pressure of the containment structure is above 10 psig.
If the design pressure is 10 psig or less, a pressure of at least one half of the design pressure shall be used.
4.5 General Preparations for Test Pressurizing. Preparatory to test pressurizing for leakage-rate determination, contents of the containment structure that are sensitive to damage by a pressure differential, such as some instruments, should be removed or other-wise protected.*
Caution should also be used in the operation of fan and blower motors employed for air circulation where the load is a function of air density.
The protection of the structure from damage, such as by underpressure, should be assured by checking
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4 The vacuum-release the operative reliability of vacuum breakers.
devices should operate within 10% of their design pressures forPneumatic li internal or external loading.
that are, or may become, pressurized should be depressu of fluids to the containment volume during test.
Note that all engineered safety feacares, including instrumentation, required for orderly shutdown and post-accident operations must be The capable of withstanding full containment design pressure.
pressure tests provide an opportunity for demonstrating this capability, To assure favorable 4.6 Time Scheduling of the Leakage-Rate Test.
test conditions for leakage-rate tests without large or abrupt changes in atmospheric temperatures or barometric pressures, the scheduling of the test should be planned, insofar as feasible, Final weather in accordance with advance weather predictions.
checks to assure safety of the containment structure should be made just prior to and during the test to assure that radical decreases-verstressing of the in barometric pressure will not c&se To minimize temperature fluctuations caused by solar radiation, wind effects, or appreciable changes in temperature, a rel The a7ticipated weather conditions during the test should indicate little or moderate barometric pressure variations is preferred.
in order to improve the reproducibility of leakage-rate results.
5 Laakage-Rate Test _ Methods Leakage-rate test procedures applicable 5 1 Applicable Test Methods.
to this standard may be either the absolute method or the reference The choice of either method shall be a matter of agre6 ment between parties who are charged with responsible acceptance vessel method.
of the containment structure and those in charge of the leakage-rate test procedures.
5 2 Description of Methods. The absolute method of leakage-rate testing shall constitute the determination and calculation of air losses by containment-structure leakage over a stated p during the period of test, with temperature detectors properlyThe reference vessel located to provide an average air temperature.
method shall constitute the determination and calculation of air losses by observations of the pressure differentials between the containment structure and a gas-tight reference system, with the reference vessels located so as to represent, with an accurac of the aggregate containment air.
6.
Test Eouipment and Facilities Pressurizing facilities for containment 6.1 Pressurizing Facilities.
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5 structure leakage-rate teots should be of sufficient capacity to bring the structure pressure to the test level within a sufficient period of time for scheduling with reference to favorable q
weather conditions.
Valves and repressurizing facilitie s should i
be available for adjusting to sbsequent atmospheric changes as I
appropriate to specific test requirements.
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6.2 Temperature Measurements.
All thermometric equipment shall be compared over a normal range of atmospheric variations with a i
reference thermometer of established calibration.
Corrections based on the reference thermometer shall be available before the leakage-rate test is started.
6.3 Pressure Measurements.
Barographs for the recording of the outside atmospheric changes need be only of such accuracy as will indicate gross barometric changes pertinent to the scheduling of tests.
All pressure measuring equipment shall be. compared with a single reference instrument.
Hygrometers and/or psychrometer shall be available to determine relative humidities during the period of test within and outside the containment stracture.
Other instruments acceptable to the responsible regu]atory agency may be substituted.
Suitable facilities shall be provided for representative sampling of the containment air for determination of the vapor-pressure effects of airborne moisture.
Instrumentation for this l
purpose shall comply with ASTM Specification 337-62.
6.4 Instrument Accuracies.
The combined precision of all instruments used shall be. such that the accuracy of the collected data is consistent with the magnitude of the specified leak rate.
7.
Test Procedures 7.1 The Absolute Method.
The absolgte method of leakage-rate determination depends on the measurement of the temperature and pressure of the containment structure atmosphere, with suitable correction for changes in humidity, under a nearly constant pressure difference with respect to the atmosphere outside the structure.
It assumes that the temperature variations during the test will be insufficient to effect significant changes in the internal volume of the structure or the partial pressure of water vapor in the contained atmosphere.
7 2 The Reference-Vessel Method.
The reference-vessel method of leakage-rate determination depends on the changes in pressure of the containment atmosphere compared with that of hermetically closed reference vessels that may be at the same pressure as the containment at the start of the test or preferably may have a small negative differential.
The reference vessels shall be so placed and of such a geometry that they will assume the temperatures of the contained atmosphere within a time lag that is compatible with the frequency of the data taking.
The reference system shall be subject to leakage-rate determination in accordance with the absolute method before and after its use for containment-structure testing according to the applicable procedures of this standard or may be checked by the halogen-sniffer test, helium indicator test, or by retention of the vacuum, i
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6 7.3 Pressurizing.
Pressurizing for the leakage-rate test shall preferably be carried out under atmospheric conditions that provide relatively low air humidity in order to avoid moisture condensation within the containment structure.
To provide low humidity and to l
improve pumping efficiency, cool night air is usually preferred.
Reference vessels should be pressurized with dry air or gas.
The structure shall be pressurized to as near the design pressure as is possible under prevailing conditions or to pressures stipulated l
as a condition for test acceptance.
l 7.4 Temperature Measurements.
Area surveys within the structure shall be made in advance of leakage-rate testing to establish any tendencies to regional variations in temperature.
Additionally, thermometers and thermocouple shall be located at different parts of the structure wherever local variations may be expected in the course of the test.
Fans or other means for air circulation may be used to equalize temperatures in any region where representative temperature measurements are taken and appreciable temperature variations exist.
The temperature pattern revealed by the survey shall be employed in connection with the mean representative temperature determination for the absolute method of leakage-rate testing.
Location of reference vessels shall be made with consideration of the temperature pattern in order to reflect representative temperatures.
Where testing experience with containment structures of various con-figurations has established appropriate locations for reference vessels, temperature surveys may be eliminated for those containment structures having similar proportions.
7 5 Personnel Access to Pressurized Containment Structures.
Exposure of personnel to pressurized air an4 return to normal atmospheric pressures during the course of conta)inment-structure leakage-rate testing shall be governed by approved decompression procedures involving a controlled depressurizing rate and waiting periods at intermediate pressures.
For exposures of no longer than 200 min.
at pressures not greater than 14.3 psig, no i* intermediate holding periods or decompression stops are required provided the time period of pressure reduction in the air lock to atmospheric level is not less than 30 sec.
For exposures to pressurization in excess of 14.3 psig, and for exposure periods including repetitive exposure within 12 hr, the practices should conform to those stipulated in Section 1.5, Diving Tables of the U.S. Navy Diving Manual, NAVSHIPS 250-538, January 1959 7.6 Period of Test.
The leakage-rate test period shall extend to not less than 24 hr. of retained internal pressure.
Leakage-rate tests should not be started until essential temperature equilibrium has been attained.
Completion of the test should preferably be scheduled to coincide with atmospheric temperatures and pressures close to those at the start of the test, as far as is possible.
Check tests or repetition of tests shall be a matter of agreement between those responsible for the acceptance of the containment structure end those in charge of the leakage-rate testing.
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7.7 Hubidity Monitoring.. The relative humidity of the containment structure shall be monitored during the course of the lea ~kage-rate test so that vapor-pressure corrections can be made.
To minimize the effect of variation in the partial pressure of water vapor, it may be desirable to maintain the containment structure air at a reasonably constant temperature level, particularly 1
near the-completion of the test.
Air ~ conditioning may be employed to approach this c ondition.
Vapor pressures due to moisture content in the containment atmosphere shall be determined by a wet-and dry-bulb aspiration' psychrometer of the Assman type or by any other method of humidity measurement acceptable to the responsible regulatory agency.
7.8 Recording of Data.
Pressure, temperature,.mid humidity.
observations shall be made within the containment structure and recorded during the course of the leakage-rate test at hourly or more frequent intervals.
Pressure and temperature measurements of the outside atmosphere shall also be made and recorded at corresponding intervals and times.
The times of observations
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shall be denoted in hours and minutes.
A dated log of events and l
pertinent observations shall also be maintained during the test, and the correctness of data shall be attested to by those responsible for the test and, where specified, by a competent witness.
Records of the leakage-rate tests shall be maintained 'in accordance with the terms of agreements with those responsible for the acceptance
.cf the containment structures.
7.9 Computation of Leakage Rate - The Absolute Method.
Because of errors introduced by deviations from stable conditions during the performance of a-leakage test, the calculation of leakage rate frcm two sets of measurements taken 24 hrs. apart may prove unreliable.
Leakage rates shall therefore'be calculated on an hourly basis for at least 24 consecutive hours.
The'1eakage determined from these hourly calcula.tions shall be plotted against time, and a statistically averaged hourly leakage rate shall be obtained by a linear least-squares fit to the resulting graph.
The i,
24-hr. leakage rate shall be equal to 24 times this averaged hourly rate.
It is suggested that the hourly leakage rates be calculated and plotted continuously during the test in order to disclose any gross variations.
For the absolute method of leakage-rate testing, the calculation of the percent leakage of air from the containment structure in terms of the original amount contained and that which escaped during each hourly test period shall be made in accordance with the following formula.
The average of at least 24 consecutive hourly determinations shall be used in establishing the percent leakage during a 24 hr. period:
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TP12 Percent Leakage = l 1-
- 100, TP
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2y j
where T
= mean absolute temperature of the containment structure air 1
at the start of each hourly test period,
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T2' = mean absolute temperature. of the containment structure air-at the end of each hourly test period,.
P1 = total absolute pressure in the containment structure at' the start of each hourly test period, P2 = total absolute pressure in the containment structure at the -
end of each hourly, test period.
The derivation of this formula is'given in Appendix B.
Under leakage test conditions' where_ condensation or evaporation of moisture is of an order to cause error, the partial pressure of water vapor should be subtracted from the total containment pressure in accordance with the following modification of the base formula:
" T (P -PV2)'
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Percent Leakage =
l--
100 T (P ~EV1),
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L where P
water-vapor. pressure at the beginning of each hourly test yy= period, PV2= water-vapor pressure at the'end of each. hourly test period.
The' partial pressures due to the presence of water vapor may be determined in.accordance with the methods provided in "A Review of the Existing.Psychrometric Data in' Relation to Practical Engineering Problems," by W. H. Carrier and C. O. Mackey, Trans. A.S.M.E.,.
vol. 59, 1937, paper PRO-59-1, p 33 - 47.
l 7.10 Computation of Leakage Rate - The Reference-Vessel Method.- For I
the reference-vessel method of leakage-rate testing, the calculation of the percent leakage of air from the containment structure in terms of the original amount contained and that which escapes.during -
each 24 hr. test period, shall be ma'de in accordance with the following formula:
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Percent Leakage =
- 2
- (P(-P)
T (P -F )
1 100 i
2 TP P
2y y
where P ' and PI are, respectively, the absolute pressure of the 1
reference vessel at the start and completion of each 24 hr. test l
period.
Under leakage-test conditions in which condensation or evaporation of moisture is of an order as to cause error, the partial pressure of water vapor should be subtracted from the containment air pressure in accordance with the following modification of the basic formula:
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9 Percent Leakage =
T (P'-P'2-P2+PV2)
Pf-Pk-P1+P i
2 V
100.
T (P -Pyy) p _p 2
y 6
The partial pressures due to the presence of water vapor may be determined in accordance with the equation provided in ASTM Standard E 337-62.
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11 APPENDICES
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'13 Appendix A Local Leak-Testing Procedures (This material is informative only and is not a part of the Standard for Leakage-Rate Tes ting of Containment Structures for Nuclear Reactors.)
A.1 Applicability of Local Leak Tests.
Local leak tests may be selected for the qualitative inspection of specific-materials or components where methods other than air preFBurizing are not objectionable and provide a more searching and convenient method.
Such tests are particularly applicable to parts of or accessories to the containment s tructure.
A.2 Water-Submersion Test.
The water-submersion test consists of covering an area that may contain a leak with clean water on the low-pressure side of a differential pressure.
The water should be such as to provide full submergence with convenient observation of bubble formation.
Repeated bubble fonnation occurring within 5 min. af ter a previous bubble has been wiped away will indicate a leak.
A 3 Vacuum Test.
The vacuum test employs a vacuum box that can be over an area to be tested and evacuated to at least a 5-psi placed pressure differential with the atmospheric pressure where the edge seals provide a tight seating closure.
Air leakage through the area tested may be r3vealed by changes in a manometer level after the absence of seating leakage is determined by soap-suds indicators.
Where real leakage is a problem, a soap solution, applied to the test area before cov3 ring with the vacuum box, will reveal leaks by bubble formation visible through a glass-covered opening in the box during a 5 min. examination Speriod.
A suitable soap solution for air-leakage indication is one consisting The of equal parts of corn syrup, liquid detergent, and glycerin.
solution should not be prepared more than 24 hr. preceding,the test, and bubble formation properties should'be checked with a Several satisfactory sample leak every half hour during the test.
commercial solutions are also available.
A.4 Air-Ammonia Test.
The air-ammonia test is an air-pressurizing Where leaks method employing anhydrous ammonia as an indicator.
are present, the leakage permeation of ammonia is revealed by a white chemical fog on probing the atmosphere with a swab wetted with 0.1 N hydrochloric acid. (Care should be taken with materials subject to chloride stress-corrosion.)
Sulpher dioxide, such as from a sulphur candle, can also be used as the revealing reactant.
Other methods employing ammonia use 1.0% phenolphthalein in a solution of equal amounts of water and ethyl alcohol.
A cloth dampened with the phenolphthalein solution and placed over the test area shows the location of leaks by a pink discoloration.
The ammonia indicator can be introduced in anhydrous gas or by placing a cloth saturated with ammonia solution within the pressurized space.
i-s 14 A.5 Halogen Sniffer Test.
The halogen sniffer test employs a halogen compound leak indicator, such as freon gas, in the pressurized air.
About 0 3 ounces per cubic foot of air is commonly used.. Leakage is revealed by' traversing the test area with a detector that senses the effects of the halogen compound on ion emission from'a heated metal surface.
Locating the leak is best accomplished by holding the sniffer at about 1/2 in, from the surface to be examined and traversing this at a rate 'of-1/2 in./sec.-
A leak is indicated by a mil 11 ammeter pointer movement or audible signal'.
Detection is also made by flame coloration from halogen-indicator additions to the contained air.
It should be' realized that halogen detectors are sensitive to cigarette smoke or vapor from dry-cleaning flaids in recently cleaned clothing.
Also, if halogen compounds are used with stress-corrosion sensitive materials, chloride attack is possible unless thorough cleaning follows this test.
If retesting is necessary, the test area should be thoroughly ventilated to avoid interference with subsequent testing.
A.6 Ultrasonic Leak Detector. Minute and localized sources of leakage may be identified and located by devices sensitive to ultrasonic sounds of escaping gas and which convert these to an audible signal.
i:
i l
i
(
15 Appendix B Derivation of Formulas for Cont e nment Struc ture Leakage Rates (This material is informative only and is not a part of the Standard for Leakage-Rate Testing of Containment Structures for Nuclear Reactors.)
B.1 Definition of Symbols.
Py = total absolute pressure in containment structure at tne start of the hourly test period, P2 = total absolute pressure in containment structure at the end of the hourly test period, T1 = mean absolute temperature at the start of the hourly test period, *F + 459 7 or *c + 273,
T2 = mean absolute temperature at completion of hourly test period, original weight of contained air at the start of wl = hourly test period, w2 = final weight of contained air at the end of hourly test period, V
= internal volume of containment structure, assumed to remain constant, R
= gas constant for a perfect gas, applicable to air for the test conditions employed, Pyy= water-vapor pressure at the start of the leakage-rate test, PV2= water-vapor pressure at the end of the leakage-rate test, T, P,, V,= reference vessel c6nditions.
B.2 Determination of Leakage Rate - The Absolute Method. In the absolute method (O'I)
PV=w1RTy and P V = w2RT2>
1 2
wT V
wT V
11 22
( 6-2.)
and
=-
=-
P1 R
P2 R
Therefore, T
T w1 1 w2 2 (dejh P1 P2
~
-(
16
'hhereby wTP-wTP 221 112 wi =
and w2 *
(A ~ )
Accordingly,
[T P I
21 Leakage =
T1P2 ),1_ Y (g_ g.}
1~ E =
TP21 TP21 W 1 TP12 and TP5 f
12 Percent Leakage =
l 1-l100 (6-4 )
'L 2 ij Corrections for changes in water-vapor pressure in the contained atmosphere shall be made by modifying the base equation as i
follows:
t T (P -PV2)
(O'7) i 2
Percent Leakage =
100 T (P -Pyl),
I-2 1
B.3 Determination of Leakage Rate - The Reference-Vessel Method.
17 the reference-vessel method P(V'=w'RT and P'V'= w'RT
(/S.g}
y 2
p ( w RTi and P'='<*
1 y/
2 y/
P 'V PV f
1 2
(ie: Assumed, Constant w
=
j with rio system leakage)
=
RT'1 RT2 (S- / d) where the prime denotes the reference-vessel conditions.
In the containment structure P V = w RT and P V = w RT kf3'$
2 2
2'
I 17 1
1 P1=
and P2*
~
V V
PV 1
wi = RT
(, r5 - 13) 1 In the system of reference vessel and containment structure, the pressure difference between the two structures is expressed by 1 / /
1 O
1=P'-P1=R AP l
y j3 f
T w 'T '
wT (b " II )
AP2=P2-P2=E
~
ye y)-
By transposition r
f f V
wT AP w1 =
( y, (Mk
( -I7)
~
w2*
R Vw' T'
Th ), V A P AP I
(6-/%)
1 2
1 wi - w2= V (T1 T
i R
T2 T1 2)
Substituting for w# the terms (P,#V/RT{}anddividingtheexpression for (wl - w2) by the equivalent Of yl, or (P V/RT ), gives 1
1
~
Percent Leakage =
7 f
f 7
-r I
100 100
+
=
k w1 kT T')
TP l T1 T2 L *P1 j
_11 2
1 Since in the leakage-rate test made with the reference-vessel method it is assumed that there is temperature equalization between the reference vessel and the containment structure air, in the 1
equation above
]
=T[andT =T[
( 6-2 O T
2 This reduces the equation to a general expression for leakage:
Percent Leakage =
1 [d P AP) 1 T
P i-wI2.
T
'w 2
y 1
2 1
1
'100 -
'100 -
-4P1 100.
/
kW1 P1 T2 T1)
P1 T2 i
(0~*2I)
a i
18 The leakage rate is expressed in percentage values for a 24-hr period.
The general expression for leakage rate becomes
\\-
/
/
1 P '100
( (J.1 Q Ti(P2-P)
P 2
l l
or:
Percent Leakage =
~TP P
y 21 1
Under the conditions in which the test is started with the pressure in the reference vessel equal to that in the containment structure, j
Pi=P, and AP1 = 0; whereby 3
Percent Leakage = [ T AP I 1
2 100.
g,y Under the c,nditions in which the test is ended with the containment structure air temperature the same as that at the start, T1 = T2, and 2 -AP ) x 100 (G, a 4)
Percent Leakage =
(AP 1
1 4 P2 x 100 if A P = 0 (ie P =P') (6-2 f)
=
y l
1 P
i 1
C,rrections for ' changes in water "apor pressure in the contained atmosphere shall be made by modifying equation B-22 as follows:
Percent Loakage =
T (P'- P'2 - P2+PV2)
P[-P'y-P
+P 7
2 V
y y
7 2
100.
T (P
~
2 1
V1 1 -
V1
/
J e
19 Appendix C
- Suggested Method for Verification of Leakage-Test Accuracy.
(This material is informative only and is not' a part of the Standard for Laakage-Rate Tosting of Containment Structures for Nuclear Reactors.)
In recognition of uncertainties associated with the performance of leakage-rate tests,' it is desirable to use a supplemental method j
of 'erifying the "alidity of. the measurements.
A method that ser9es such< e purpore involves the accurate measurement of the leakage rate through a calibrated leak intentionally superimposed on the existing leaks in a containment structure.
A practical and simple arrangement for superimposing a controlled and measurable leak on the containment vessel employs the orifice leak of a microadjurtable instrument flow valve installed at a convenient penetration of the c,ntainment vessel.
The flow through the valve ~in measured by means of a suitable flowmeter or rotameter.
The leak orifice is selected to provide a flow under the. test-pressure condition approximately equivalent to the leakage. rate specified for the containment vessel.
The test procedure involves placing the calibrated leak system into operation af ter the leakage-rate test in progress is completed.
The flow meter. readings are then recorded hourly over an interval-of approximately 12 hr.
Concurrently, readings, of the vessel leakage-measuring s," stem, which now records the composite leakage of both the containment vessel leaks and the superimposed orifice leak, are' resumed on an hourly basiIs.
. The. readings of the flowmeter as a function of time enable calculation of the average leakage rate, Lo,.through the calibrated orifice.
From the analysis of the hourly readings taken with the "essel leakage-measuring system, the composite leakage rate, L, is determined.
The vessel leakage rate, L, through e
containment vessel leaks is then obtained by deducting the orifice-measured leakage rate from the composite leakage rate, L ; thus c
L'=L
-b b~
y c
o*
. If the result of the leakage measurements obtained prior to the introduction of the superimposed orifice' leak yields a leakage rate, L, in reasonable agreement with the calculated value, L'.
y the accuraev of the vessel leakage-measuring system is verified and the leakage-rate results validated.