Appendix J to Part 50 - Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors
10:184.108.40.206.220.127.116.11.32 : Appendix J
Appendix J to Part 50 - Primary Reactor Containment Leakage Testing
for Water-Cooled Power Reactors
This appendix includes two options, A and B, either of which can
be chosen for meeting the requirements of this appendix.
Option A - Prescriptive Requirements Table of Contents
II. Explanation of terms.
III. Leakage test requirements.
A. Type A test.
B. Type B test.
C. Type C test.
D. Periodic retest schedule.
IV. Special test requirements.
A. Containment modifications.
B. Multiple leakage-barrier containments.
V. Inspection and reporting of tests.
A. Containment inspection.
B. Repordkeeping of test results.
One of the conditions of all operating licenses under this part
and combined licenses under part 52 of this chapter for
water-cooled power reactors as specified in § 50.54(o) is that
primary reactor containments shall meet the containment leakage
test requirements set forth in this appendix. These test
requirements provide for preoperational and periodic verification
by tests of the leak-tight integrity of the primary reactor
containment, and systems and components which penetrate containment
of water-cooled power reactors, and establish the acceptance
criteria for these tests. The purposes of the tests are to assure
that (a) leakage through the primary reactor containment and
systems and components penetrating primary containment shall not
exceed allowable leakage rate values as specified in the technical
specifications or associated bases; and (b) periodic surveillance
of reactor containment penetrations and isolation valves is
performed so that proper maintenance and repairs are made during
the service life of the containment, and systems and components
penetrating primary containment. These test requirements may also
be used for guidance in establishing appropriate containment
leakage test requirements in technical specifications or associated
bases for other types of nuclear power reactors.
II. Explanation of Terms
A. “Primary reactor containment” means the structure or vessel
that encloses the components of the reactor coolant pressure
boundary, as defined in § 50.2, and serves as an essentially
leak-tight barrier against the uncontrolled release of
radioactivity to the environment.
B. “Containment isolation valve” means any valve which is relied
upon to perform a containment isolation function.
C. “Reactor containment leakage test program” includes the
performance of Type A, Type B, and Type C tests, described in II.F,
II.G, and II.H, respectively.
D. “Leakage rate” for test purposes is that leakage which occurs
in a unit of time, stated as a percentage of weight of the original
content of containment air at the leakage rate test pressure that
escapes to the outside atmosphere during a 24-hour test period.
E. “Overall integrated leakage rate” means that leakage rate
which obtains from a summation of leakage through all potential
leakage paths including containment welds, valves, fittings, and
components which penetrate containment.
F. “Type A Tests” means tests intended to measure the primary
reactor containment overall integrated leakage rate (1) after the
containment has been completed and is ready for operation, and (2)
at periodic intervals thereafter.
G. “Type B Tests” means tests intended to detect local leaks and
to measure leakage across each pressure-containing or
leakage-limiting boundary for the following primary reactor
1. Containment penetrations whose design incorporates resilient
seals, gaskets, or sealant componds, piping penetrations fitted
with expansion bellows, and electrical penetrations fitted with
flexible metal seal assemblies.
2. Air lock door seals, including door operating mechanism
penetrations which are part of the containment pressure
3. Doors with resilient seals or gaskets except for seal-welded
4. Components other than those listed in II.G.1, II.G.2, or
II.G.3 which must meet the acceptance criteria in III.B.3.
H. “Type C Tests” means tests intended to measure containment
isolation valve leakage rates. The containment isolation valves
included are those that:
1. Provide a direct connection between the inside and outside
atmospheres of the primary reactor containment under normal
operation, such as purge and ventilation, vacuum relief, and
2. Are required to close automatically upon receipt of a
containment isolation signal in response to controls intended to
effect containment isolation;
3. Are required to operate intermittently under postaccident
4. Are in main steam and feedwater piping and other systems
which penetrate containment of direct-cycle boiling water power
I. Pa (p.s.i.g.) means the calculated peak containment internal
pressure related to the design basis accident and specified either
in the technical specification or associated bases.
J. Pt (p.s.i.g.) means the containment vessel reduced test
pressure selected to measure the integrated leakage rate during
periodic Type A tests.
K. La (percent/24 hours) means the maximum allowable leakage
rate at pressure Pa as specified for preoperational tests in the
technical specifications or associated bases, and as specified for
periodic tests in the operating license or combined license,
including the technical specifications in any referenced design
certification or manufactured reactor used at the facility.
L. Ld (percent/24 hours) means the design leakage rate at
pressure, Pa, as specified in the technical specifications or
M. Lt (percent/24 hours) means the maximum allowable leakage
rate at pressure Pt derived from the preoperational test data as
specified in III.A.4.(a)(iii).
N. Lam, Ltm (percent/24 hours) means the total measured
containment leakage rates at pressure Pa and Pt, respectively,
obtained from testing the containment with components and systems
in the state as close as practical to that which would exist under
design basis accident conditions (e.g., vented, drained, flooded or
O. “Acceptance criteria” means the standard against which test
results are to be compared for establishing the functional
acceptability of the containment as a leakage limiting
III. Leakage Testing Requirements
A program consisting of a schedule for conducting Type A, B, and
C tests shall be developed for leak testing the primary reactor
containment and related systems and components penetrating primary
containment pressure boundary.
Upon completion of construction of the primary reactor
containment, including installation of all portions of mechanical,
fluid, electrical, and instrumentation systems penetrating the
primary reactor containment pressure boundary, and prior to any
reactor operating period, preoperational and periodic leakage rate
tests, as applicable, shall be conducted in accordance with the
A. Type A test - 1. Pretest requirements. (a)
Containment inspection in accordance with V. A. shall be performed
as a prerequisite to the performance of Type A tests. During the
period between the initiation of the containment inspection and the
performance of the Type A test, no repairs or adjustments shall be
made so that the containment can be tested in as close to the “as
is” condition as practical. During the period between the
completion of one Type A test and the initiation of the containment
inspection for the subsequent Type A test, repairs or adjustments
shall be made to components whose leakage exceeds that specified in
the technical specification as soon as practical after
identification. If during a Type A test, including the supplemental
test specified in III.A.3.(b), potentially excessive leakage paths
are identified which will interfere with satisfactory completion of
the test, or which result in the Type A test not meeting the
acceptance criteria III.A.4.(b) or III.A.5.(b), the Type A test
shall be terminated and the leakage through such paths shall be
measured using local leakage testing methods. Repairs and/or
adjustments to equipment shall be made and Type A test performed.
The corrective action taken and the change in leakage rate
determined from the tests and overall integrated leakage determined
from local leak and Type A tests shall be included in the summary
report required by V.B.
(b) Closure of containment isolation valves for the Type A test
shall be accomplished by normal operation and without any
preliminary exercising or adjustments (e.g., no tightening of valve
after closure by valve motor). Repairs of maloperating or leaking
valves shall be made as necessary. Information on any valve closure
malfunction or valve leakage that require corrective action before
the test, shall be included in the summary report required by
(c) The containment test conditions shall stabilize for a period
of about 4 hours prior to the start of a leakage rate test.
(d) Those portions of the fluid systems that are part of the
reactor coolant pressure boundary and are open directly to the
containment atmosphere under post-accident conditions and become an
extension of the boundary of the containment shall be opened or
vented to the containment atmosphere prior to and during the test.
Portions of closed systems inside containment that penetrate
containment and rupture as a result of a loss of coolant accident
shall be vented to the containment atmosphere. All vented systems
shall be drained of water or other fluids to the extent necessary
to assure exposure of the system containment isolation valves to
containment air test pressure and to assure they will be subjected
to the post accident differential pressure. Systems that are
required to maintain the plant in a safe condition during the test
shall be operable in their normal mode, and need not be vented.
Systems that are normally filled with water and operating under
post-accident conditions, such as the containment heat removal
system, need not be vented. However, the containment isolation
valves in the systems defined in III.A.1.(d) shall be tested in
accordance with III.C. The measured leakage rate from these tests
shall be included in the summary report required by V.B.
2. Conduct of tests. Preoperational leakage rate tests at
either reduced or at peak pressure, shall be conducted at the
intervals specified in III.D.
3. Test Methods. (a) All Type A tests shall be conducted
in accordance with the provisions of the American National
Standards N45.4-1972, “Leakage Rate Testing of Containment
Structures for Nuclear Reactors,” March 16, 1972. In addition to
the Total time and Point-to-Point methods described in that
standard, the Mass Point Method, when used with a test duration of
at least 24 hours, is an acceptable method to use to calculate
leakage rates. A typical description of the Mass Point method can
be found in the American National Standard ANSI/ANS 56.8-1987,
“Containment System Leakage Testing Requirements,” January 20,
1987. Incorporation of ANSI N45.4-1972 by reference was approved by
the Director of the Federal Register. Copies of this standard, as
well as ANSI/ANS-56.8-1987, “Containment System Leakage Testing
Requirements” (dated January 20, 1987) may be obtained from the
American Nuclear Society, 555 North Kensington Avenue, La Grange
Park, IL 60525. A copy of each of these standards is available for
inspection at the NRC Library, 11545 Rockville Pike, Rockville,
(b) The accuracy of any Type A test shall be verified by a
supplemental test. An acceptable method is described in Appendix C
of ANSI N45.4-1972. The supplemental test method selected shall be
conducted for sufficient duration to establish accurately the
change in leakage rate between the Type A and supplemental test.
Results from this supplemental test are acceptable provided the
difference between the supplemental test data and the Type A test
data is within 0.25 La (or 0.25 Lt). If results are not within 0.25
La (or 0.25 Lt), the reason shall be determined, corrective action
taken, and a successful supplemental test performed.
(c) Test leakage rates shall be calculated using absolute values
corrected for instrument error.
4. Preoperational leakage rate tests. (a) Test
pressure - (1) Reduced pressure tests. (i) An initial
test shall be performed at a pressure Pt, not less than 0.50 Pa to
measure a leakage rate Ltm.
(ii) A second test shall be performed at pressure Pa to measure
a leakage rate Lam.
(iii) The leakage characteristics yielded by measurements Ltm
and Lam shall establish the maximum allowable test leakage rate Lt
of not more than La (Ltm/Lam). In the event Ltm/Lam is greater than
0.7, Lt shall be specified as equal to La (Pt/Pa). 1
1 Such inservice inspections are required by § 50.55a.
(2) Peak pressure tests. A test shall be performed at
pressure Pa to measure the leakage rate Lam.
(b) Acceptance criteria - (1) Reduced pressure
tests. The leakage rate Ltm shall be less than 0.75 Lt.
(2) Peak pressure tests. The leakage rate Lam shall be
less than 0.75 La and not greater than Ld.
5. Periodic leakage rate tests - (a) Test
pressure. (1) Reduced pressure tests shall be conducted at
(2) Peak pressure tests shall be conducted at Pa.
(b) Acceptance criteria - (1) Reduced pressure
tests. The leakage rate Ltm shall be less than 0.75 Lt. If
local leakage measurements are taken to effect repairs in order to
meet the acceptance criteria, these measurements shall be taken at
a test pressure Pt.
(2) Peak pressure tests. The leakage rate Lam shall be
less than 0.75 La. If local leakage measurements are taken to
effect repairs in order to meet the acceptance criteria, these
measurements shall be taken at a test pressure Pa.
6. Additional requirements. (a) If any periodic Type A
test fails to meet the applicable acceptance criteria in
III.A.5.(b), the test schedule applicable to subsequent Type A
tests will be reviewed and approved by the Commission.
(b) If two consecutive periodic Type A tests fail to meet the
applicable acceptance criteria in III.A.5(b), notwithstanding the
periodic retest schedule of III.D., a Type A test shall be
performed at each plant shutdown for refueling or approximately
every 18 months, whichever occurs first, until two consecutive Type
A tests meet the acceptance criteria in III.A.5(b), after which
time the retest schedule specified in III.D. may be resumed.
B. Type B tests - 1. Test methods. Acceptable
means of performing preoperation and periodic Type B tests
(a) Examination by halide leak-detection method (or by other
equivalent test methods such as mass spectrometer) of a test
chamber, pressurized with air, nitrogen, or pneumatic fluid
specified in the technical specifications or associated bases and
constructed as part of individual containment penetrations.
(b) Measurement of the rate of pressure loss of the test chamber
of the containment penetration pressurized with air, nitrogen, or
pneumatic fluid specified in the technical specifications or
(c) Leakage surveillance by means of a permanently installed
system with provisions for continuous or intermittent
pressurization of individual or groups of containment penetrations
and measurement of rate of pressure loss of air, nitrogen, or
pneumatic fluid specified in the technical specification or
associated bases through the leak paths.
2. Test pressure. All preoperational and periodic Type B
tests shall be performed by local pneumatic pressurization of the
containment penetrations, either individually or in groups, at a
pressure not less than Pa.
3. Acceptance criteria. (See also Type C tests.) (a) The
combined leakage rate of all penetrations and valves subject to
Type B and C tests shall be less than 0.60 La, with the exception
of the valves specified in III.C.3.
(b) Leakage measurements obtained through component leakage
surveillance systems (e.g., continuous pressurization of individual
containment components) that maintains a pressure not less than Pa
at individual test chambers of containment penetrations during
normal reactor operation, are acceptable in lieu of Type B
C. Type C tests - 1. Test method. Type C tests
shall be performed by local pressurization. The pressure shall be
applied in the same direction as that when the value would be
required to perform its safety function, unless it can be
determined that the results from the tests for a pressure applied
in a different direction will provide equivalent or more
conservative results. The test methods in III.B.1 may be
substituted where appropriate. Each valve to be tested shall be
closed by normal operation and without any preliminary exercising
or adjustments (e.g., no tightening of valve after closure by valve
2. Test pressure. (a) Valves, unless pressurized with
fluid (e.g., water, nitrogen) from a seal system, shall be
pressurized with air or nitrogen at a pressure of Pa.
(b) Valves, which are sealed with fluid from a seal system shall
be pressurized with that fluid to a pressure not less than 1.10
3. Acceptance criterion. The combined leakage rate for
all penetrations and valves subject to Type B and C tests shall be
less than 0.60 La. Leakage from containment isolation valves that
are sealed with fluid from a seal system may be excluded when
determining the combined leakage rate: Provided, That;
(a) Such valves have been demonstrated to have fluid leakage
rates that do not exceed those specified in the technical
specifications or associated bases, and
(b) The installed isolation valve seal-water system fluid
inventory is sufficient to assure the sealing function for at least
30 days at a pressure of 1.10 Pa.
D. Periodic retest schedule - 1. Type A test. (a)
After the preoperational leakage rate tests, a set of three Type A
tests shall be performed, at approximately equal intervals during
each 10-year service period. The third test of each set shall be
conducted when the plant is shutdown for the 10-year plant
inservice inspections. 2
2 Such inservice inspections are required by § 50.55a.
(b) Permissible periods for testing. The performance of Type A
tests shall be limited to periods when the plant facility is
non-operational and secured in the shutdown condition under the
administrative control and in accordance with the safety procedures
defined in the license.
2. Type B tests. (a) Type B tests, except tests for air
locks, shall be performed during reactor shutdown for refueling, or
other convenient intervals, but in no case at intervals greater
than 2 years. If opened following a Type A or B test, containment
penetrations subject to Type B testing shall be Type B tested prior
to returning the reactor to an operating mode requiring containment
integrity. For primary reactor containment penetrations employing a
continuous leakage monitoring system, Type B tests, except for
tests of air locks, may, notwithstanding the test schedule
specified under III.D.1., be performed every other reactor shutdown
for refueling but in no case at intervals greater than 3 years.
(b)(i) Air locks shall be tested prior to initial fuel loading
and at 6-month intervals thereafter at an internal pressure not
less than Pa.
(ii) Air locks opened during periods when containment integrity
is not required by the plant's Technical Specifications shall be
tested at the end of such periods at not less than Pa.
(iii) Air locks opened during periods when containment integrity
is required by the plant's Technical Specifications shall be tested
within 3 days after being opened. For air lock doors opened more
frequently than once every 3 days, the air lock shall be tested at
least once every 3 days during the period of frequent openings. For
air lock doors having testable seals, testing the seals fulfills
the 3-day test requirements. In the event that the testing for this
3-day interval cannot be at Pa, the test pressure shall be as
stated in the Technical Specifications. Air lock door seal testing
shall not be substituted for the 6-month test of the entire air
lock at not less than Pa.
(iv) The acceptance criteria for air lock testing shall be
stated in the Technical Specifications.
3. Type C tests. Type C tests shall be performed during
each reactor shutdown for refueling but in no case at intervals
greater than 2 years.
IV. Special Testing Requirements
A. Containment modification. Any major modification,
replacement of a component which is part of the primary reactor
containment boundary, or resealing a seal-welded door, performed
after the preoperational leakage rate test shall be followed by
either a Type A, Type B, or Type C test, as applicable for the area
affected by the modification. The measured leakage from this test
shall be included in the summary report required by V.B. The
acceptance criteria of III.A.5.(b), III.B.3., or III.C.3., as
appropriate, shall be met. Minor modifications, replacements, or
resealing of seal-welded doors, performed directly prior to the
conduct of a scheduled Type A test do not require a separate
B. Multiple leakage barrier or subatmospheric
containments. The primary reactor containment barrier of a
multiple barrier or subatmospheric containment shall be subjected
to Type A tests to verify that its leakage rate meets the
requirements of this appendix. Other structures of multiple barrier
or subatmospheric containments (e.g., secondary containments for
boiling water reactors and shield buildings for pressurized water
reactors that enclose the entire primary reactor containment or
portions thereof) shall be subject to individual tests in
accordance with the procedures specified in the technical
specifications, or associated bases.
V. Inspection and Reporting of Tests
A. Containment inspection. A general inspection of the
accessible interior and exterior surfaces of the containment
structures and components shall be performed prior to any Type A
test to uncover any evidence of structural deterioration which may
affect either the containment structural integrity or
leak-tightness. If there is evidence of structural deterioration,
Type A tests shall not be performed until corrective action is
taken in accordance with repair procedures, non destructive
examinations, and tests as specified in the applicable code
specified in § 50.55a at the commencement of repair work. Such
structural deterioration and corrective actions taken shall be
included in the summary report required by V.B.
B. Recordkeeping of test results. 1. The preoperational
and periodic tests must be documented in a readily available
summary report that will be made available for inspection, upon
request, at the nuclear power plant. The summary report shall
include a schematic arrangement of the leakage rate measurement
system, the instrumentation used, the supplemental test method, and
the test program selected as applicable to the preoperational test,
and all the subsequent periodic tests. The report shall contain an
analysis and interpretation of the leakage rate test data for the
Type A test results to the extent necessary to demonstrate the
acceptability of the containment's leakage rate in meeting
2. For each periodic test, leakage test results from Type A, B,
and C tests shall be included in the summary report. The summary
report shall contain an analysis and interpretation of the Type A
test results and a summary analysis of periodic Type B and Type C
tests that were performed since the last type A test. Leakage test
results from type A, B, and C tests that failed to meet the
acceptance criteria of III.A.5(b), III.B.3, and III.C.3,
respectively, shall be included in a separate accompanying summary
report that includes an analysis and interpretation of the test
data, the least squares fit analysis of the test data, the
instrumentation error analysis, and the structural conditions of
the containment or components, if any, which contributed to the
failure in meeting the acceptance criteria. Results and analyses of
the supplemental verification test employed to demonstrate the
validity of the leakage rate test measurements shall also be
Option B - Performance-Based Requirements Table of Contents I.
Introduction. II. Definitions. III. Performance-based leakage-test
requirements. A. Type A test. B. Type B and C tests. IV.
Recordkeeping. V. Application. I. Introduction
One of the conditions required of all operating licenses and
combined licenses for light-water-cooled power reactors as
specified in § 50.54(o) is that primary reactor containments meet
the leakage-rate test requirements in either Option A or B of this
appendix. These test requirements ensure that (a) leakage through
these containments or systems and components penetrating these
containments does not exceed allowable leakage rates specified in
the technical specifications; and (b) integrity of the containment
structure is maintained during its service life. Option B of this
appendix identifies the performance-based requirements and criteria
for preoperational and subsequent periodic leakage-rate testing.
3 Specific guidance concerning a performance-based leakage-test
program, acceptable leakage-rate test methods, procedures, and
analyses that may be used to implement these requirements and
criteria are provided in Regulatory Guide 1.163, “Performance-Based
Containment Leak-Test Program.”
Performance criteria means the performance standards
against which test results are to be compared for establishing the
acceptability of the containment system as a leakage-limiting
Containment system means the principal barrier, after the
reactor coolant pressure boundary, to prevent the release of
quantities of radioactive material that would have a significant
radiological effect on the health of the public.
Overall integrated leakage rate means the total leakage
rate through all tested leakage paths, including containment welds,
valves, fittings, and components that penetrate the containment
La (percent/24 hours) means the maximum allowable leakage
rate at pressure Pa as specified in the Technical
Pa (p.s.i.g) means the calculated peak containment
internal pressure related to the design basis loss-of-coolant
accident as specified in the Technical Specifications.
III. Performance-Based Leakage-Test Requirements A. Type A Test
Type A tests to measure the containment system overall
integrated leakage rate must be conducted under conditions
representing design basis loss-of-coolant accident containment peak
pressure. A Type A test must be conducted (1) after the containment
system has been completed and is ready for operation and (2) at a
periodic interval based on the historical performance of the
overall containment system as a barrier to fission product releases
to reduce the risk from reactor accidents. A general visual
inspection of the accessible interior and exterior surfaces of the
containment system for structural deterioration which may affect
the containment leak-tight integrity must be conducted prior to
each test, and at a periodic interval between tests based on the
performance of the containment system. The leakage rate must not
exceed the allowable leakage rate (La) with margin, as specified in
the Technical Specifications. The test results must be compared
with previous results to examine the performance history of the
overall containment system to limit leakage.
B. Type B and C Tests
Type B pneumatic tests to detect and measure local leakage rates
across pressure retaining, leakage-limiting boundaries, and Type C
pneumatic tests to measure containment isolation valve leakage
rates, must be conducted (1) prior to initial criticality, and (2)
periodically thereafter at intervals based on the safety
significance and historical performance of each boundary and
isolation valve to ensure the integrity of the overall containment
system as a barrier to fission product release to reduce the risk
from reactor accidents. The performance-based testing program must
contain a performance criterion for Type B and C tests,
consideration of leakage-rate limits and factors that are
indicative of or affect performance, when establishing test
intervals, evaluations of performance of containment system
components, and comparison to previous test results to examine the
performance history of the overall containment system to limit
leakage. The tests must demonstrate that the sum of the leakage
rates at accident pressure of Type B tests, and pathway leakage
rates from Type C tests, is less than the performance criterion
(La) with margin, as specified in the Technical Specification.
The results of the preoperational and periodic Type A, B, and C
tests must be documented to show that performance criteria for
leakage have been met. The comparison to previous results of the
performance of the overall containment system and of individual
components within it must be documented to show that the test
intervals established for the containment system and components
within it are adequate. These records must be available for
inspection at plant sites.
If the test results exceed the performance criteria (La) as
defined in the plant Technical Specifications, those exceedances
must be assessed for Emergency Notification System reporting under
§ 50.72 (b)(2)(i), and for a Licensee Event Report under § 50.73
V. Application A. Applicability
The requirements in either or both Option B, III.A for Type A
tests, and Option B, III.B for Type B and C tests, may be adopted
on a voluntary basis by an operating nuclear power reactor licensee
as specified in § 50.54 in substitution of the requirements for
those tests contained in Option A of this appendix. If the
requirements for tests in Option B, III.A or Option B, III.B are
implemented, the recordkeeping requirements in Option B, IV for
these tests must be substituted for the reporting requirements of
these tests contained in Option A of this appendix.
1. Specific exemptions to Option A of this appendix that have
been formally approved by the AEC or NRC, according to 10 CFR
50.12, are still applicable to Option B of this appendix if
necessary, unless specifically revoked by the NRC.
2. A licensee or applicant for an operating license under this
part or a combined license under part 52 of this chapter may adopt
Option B, or parts thereof, as specified in Section V.A of this
appendix, by submitting its implementation plan and request for
revision to technical specifications (see paragraph B.3 of this
section) to the Director, Office of Nuclear Reactor Regulation.
3. The regulatory guide or other implementation document used by
a licensee or applicant for an operating license under this part or
a combined license under part 52 of this chapter to develop a
performance-based leakage-testing program must be included, by
general reference, in the plant technical specifications. The
submittal for technical specification revisions must contain
justification, including supporting analyses, if the licensee
chooses to deviate from methods approved by the Commission and
endorsed in a regulatory guide.
4. The detailed licensee programs for conducting testing under
Option B must be available at the plant site for NRC
[38 FR 4386, Feb. 14, 1973; 38 FR 5997, Mar. 6, 1973, as amended at
41 FR 16447, Apr. 19, 1976; 45 FR 62789, Sept. 22, 1980; 51 FR
40311, Nov. 6, 1986; 53 FR 45891, Nov. 15, 1988; 57 FR 61786, Dec.
29, 1992; 59 FR 50689, Oct. 5, 1994; 60 FR 13616, Mar. 14, 1995; 60
FR 49504, Sept. 26, 1995; 72 FR 49508, Aug. 28, 2007; 73 FR 5723,
Jan. 31, 2008; 84 FR 63568, Nov. 18, 2019; 84 FR 65644, Nov. 29]