Information Notice No. 85-71: Containment Integrated Leak Rate Tests
SSINS No.: 6835
IN 85-71
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
August 22, 1985
Information Notice No. 85-71: CONTAINMENT INTEGRATED LEAK RATE TESTS
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or a
construction permit (CP).
Purpose:
This information notice is provided as a notification of a potentially
significant problem pertaining to containment integrated leak rate tests
(CILRTs). It is expected that recipients will review the information for
applicability to their facilities and consider actions, if appropriate, to
preclude a similar problem occurring at their facilities. However, the
suggestion contained in this information notice (namely, that licensees
review their programs with respect to the guidelines provided), does not
constitute an NRC requirement. Therefore, no specific action or written
response is required.
Description of Circumstances:
Recent staff reviews of the CILRTs performed at San Onofre, Kewaunee, and
Monticello nuclear power plants have indicated that many utilities are
misinterpreting the relationship between local leak rate testing and CILRTs.
10 CFR 50, Appendix J, discusses containment leakage testing in terms of
Type A, B, and C tests. The Type A test is a measurement of the overall
integrated leakage rate of the primary containment; whereas Type B and C
tests are local leak rate tests designed to detect and measure local leakage
across each pressure-containing or leakage-limiting boundary for primary
containment.
As a result of Type B and C tests, some utilities are performing repairs and
adjustments before conducting Type A tests without properly adjusting the
Type A test results for the Type B and C leakage rates. Without this
adjustment, the "as found" condition of the primary containment cannot be
properly determined.
In some cases, when this adjustment is made properly, a Type A test may fail
to meet the acceptance criteria if Appendix J with regards to the "as found"
condition. When two successive Type A test failures occur, Appendix J
requires more frequent CILRTs. However, if, Type, B and C leakage rates
constitute an identified contributor to this failure of the "as found"
condition for the CILRT, the general purpose of maintaining a high degree of
containment integrity might be better served through an improved maintenance
and testing program for
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containment penetration boundaries and isolation valves. In this situation,
the licensee may submit a Corrective Action Plan with an alternative leakage
test program proposal as an exemption request for NRC staff review. If this
submittal is approved by the NRC staff, the licensee may implement the
corrective action and alternative leakage test program in lieu of the
required increase in Type A test frequency incurred after the failure of two
successive Type A tests.
Discussion:
Sections III.D.1.a, 2.a and 3.a of Appendix J require that a set of three
periodic Type A tests be performed at approximately equal intervals during
each 10-year service period, and that Type B and C tests be performed during
reactor shutdown for refueling but in no case at intervals greater than 2
years. Under these test requirements, there are many occasions when Type A,
B, and C tests must be performed during the same reactor shutdown period.
Questions are frequently raised concerning the correct sequence of
conducting the Type A, B, and C tests and the potential impact of the
results of the Type B and C tests on the success or failure of a periodic
Type A test.
The NRC staff has previously provided partial guidance to utilities on these
questions on an individual case basis with respect to inspection and
enforcement activities (see Attachment 1). The staff position on these
questions, as previously employed in inspection and enforcement, may be
summarized as follows:
1. Section III.A.3 of Appendix J requires that all CILRTs be conducted in
accordance with the provisions of ANSI N45.4-1972. Paragraph 4.2 of
ANSI N45.4-1972 states that for periodic CILRTs no repairs or
adjustments are to be made to the containment structure prior to
conducting the test in order to disclose the normal state of repair of
the containment structure.
2. Type B and C tests may be performed either before the start of or after
completion of the periodic Type A test provided that the pretest
requirements of Paragraph 4.2 of ANSI N45.4-1972 and Section III.A.1.a
of Appendix J are met; i.e., no repairs or adjustments to the primary
containment boundary are made so that the containment can be tested in
as close to the "as is" condition as practical. As such, the leakage
information obtained from the "as is" (sometimes called "as found")
Type A test results can be used to assess the containment condition and
its integrity following a period of plant operation.
3. If repairs or adjustments performed as a result of the Type B and C
testing programs or for any other reasons are made to the primary
containment boundary before the Type A test sequence, local leak tests
must be performed on the affected portion of the containment boundary
to determine the minimum pathway leakage rates before and after the
repairs or adjustments are made. The minimum pathway leakage would be
the smaller leakage rate of in-series valves tested individually,
one-half the leakage rate
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for in-series valves tested simultaneously by pressurizing between the
valves, and the combined leakage rate for valves tested in parallel.
The "as found" Type A test results can then be obtained by adding the
differences between the affected minimum path leakage before and after
repairs or adjustments to the overall measured Type A test result. A
periodic Type A test would be called a "failure" if the "as found" Type
A test result (with appropriate correction from local leak tests),
exceeds the acceptance criteria of Appendix J.
4. The question has been raised by various utilities as to how far in
advance of the Type A test the Type B and C tests may be conducted
without having to add the leakage differences to the Type A test
results. The staff position on this question has been that after Type
B and C tests, the penetrations and valves should experience some
period-of normal service conditions before the Type A test. If the Type
B and C tests are conducted before the Type A test during the same
refueling outage, the service condition criterion would not be met. If,
however, some operating service time is achieved, the Type A test can
be conducted essentially independent of the time duration of exposure
to the normal service conditions. Thereafter, a Type A test could be
conducted without having to consider the local leak rate results in
determining the "as found" condition.
The continuance of containment leak-tight integrity is the primary
importance in performing Type A, B, and C tests. Therefore, it may be
beneficial for licensees to implement improved maintenance and testing
programs for containment penetrations to ensure that known or likely leaking
penetrations will not result in the overall loss of containment leak-tight
integrity and in the ensuing penalties for Type A test failure.
It should also be noted that containment leak-tight integrity is monitored
between CILRTs through the Type B and C test programs. Failure to meet the
acceptance criteria of Appendix J for those tests generally constitutes a
loss of containment integrity as defined in the Technical Specifications and
may be reportable by the licensee under the provisions of 10 CFR 50.73.,
Sections (a)(2)(ii) and (a)(2)(v)(C).
It is suggested that licensees review their CILRT program with respect to
the above guidelines.
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No specific action or written response is required by this information
notice; however, if you have any questions regarding this notice, please
contact the Regional Administrator of the appropriate NRC regional office or
the technical contacts listed below.
Edward L. Jordan Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contacts: Y. S. Huang, NRR
(301) 492-9493
D. C. Kirkpatrick, IE
(301) 492-4510
S. A. McNeil, IE
(301) 492-9602
Attachments:
1. Documentation from NRC to Utilities, Related to Repairs and
Adjustments Done Prior to Type A Tests
2. List of Recently Issued IE Information Notices
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Attachment 1
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Documentation from NRC to Utilities, Related to
Repairs and Adjustments Done
Prior to Type A Tests
1. Letter to Consumers Power Company from R. L. Spessard, "Big Rock Point
CILRT Schedule," February 3, 1983
This letter informed the licensee of the necessity to increase the
CILRT frequency because of the failure of two consecutive Type A tests
conducted in 1977 and 1982. During the 1982 refueling outage, Type B
and C tests were conducted and several valves were found to leak
excessively and were repaired. Subsequently the Type A test was
conducted and the licensee reported a successful test, but it did not
include the initial Types B and C leakage in the Type A test results.
The NRC staff reviewed the tests and determined that the Type B and C
leakage should be added to the Type A test results, because the plant
had not been in service between the time of the Type B and C tests and
the Type A test. With the addition of the Type B and C leakage to the
Type A test result, the leakage was excessive and the containment was
deemed to have failed the "as found" test condition.
2. Letter to Commonwealth Edison Company from R. L. Spessard, "Quad Cities
Unit 1 Containment Integrated Leak Rate Test Frequency" October 7,
1983.
This letter also informed the licensee of the necessity to increase the
CILRT frequency because of the failure of two consecutive Type A tests.
These tests were conducted in 1979 and 1982. Type B and C tests
conducted during the 1982 refueling outage, prior to the Type A test,
showed that the combined leakage from several valves exceeded the
allowable Technical Specification. In addition, the seal between the
drywell head and the drywell vessel flange was found to be leaking to
such an extent that the leakage could not be measured. The licensee
repaired these leaks and then conducted a Type A test that showed the
leakage to be within the allowable limits. The NRC staff, however,
determined that the containment had failed the CILRT with respect to
the "as found" condition. This determination was based on the position
that the Type B and C test results could be excluded from the "as found
condition" only if some period of normal station service existed
between Type B and C tests and the Type A test.
3. Inspection Report No. 50-305/84-19 (DRS), Kewaunee, November 27, 1984
and Notice of Violation to Wisconsin Public Service Corporation -
Docket No. 50-305, November 28, 1984.
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Attachment 1
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The inspection report discusses an exemption to Appendix J issued to
Wisconsin Public Service Corporation by the NRC. The exemption
permitted Type B and C tests and repair work on penetrations to be
performed at Kewaunee before Type A tests were conducted. The exemption
required that leakage reduction caused by the repairs be added to the
Type A test result for the purpose of evaluating the "as found"
condition. The licensee then wrote to the NRC stating that it did not
believe that an exemption was required to perform Types B and C tests
before performing a Type A test. The licensee based this on the belief
that Type A testing and Type B and C testing were two separate events
performed on two separate schedules.
In 1984, the licensee performed Type B and C tests before performing
the Type A test and failed to add the pre- and post-repair differential
Leakage to the "as found" Type A test results in its CILRT report. As
stated in the inspection report, the NRC staff did not agree with the
licensee's position because Type B and C testing (with repair) would
invalidate part of the purpose of the Type A test (that is, to
establish the "as found" condition). As a result, the notice of
violation covering this failure was issued on November 28, 1984.
4. Inspection Report No. 50-206/85-12 San Onofre Unit 1, April 5, 1985.
Paragraph 6 of this report discusses the results of the CILRT performed
at San Onofre during 1985. Type C testing and repair work was performed
on six sets of valves just before the Type A test was conducted.
However, differential leakage resulting from the repair was not added
to the Type A test results reported. As a result a notice of violation
covering this failure is under consideration.
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