[Federal Register Volume 60, Number 52 (Friday, March 17, 1995)]
[Notices]
[Pages 14468-14470]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-6616]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-373 50-374
Exemption
In the Matter of Commonwealth Edison Co., LaSalle County
Station, Units 1 and 2.
I
Commonwealth Edison Company (ComEd, the licensee) is the holder of
Facility Operating License Nos. NPF-11 and NPF-18, which authorize
operation of the LaSalle County Station, Units 1 and 2 (the facility),
at a steady state power level not in excess of 3323 megawatts thermal.
The facility consists of two boiling water reactors at the licensee's
site located in LaSalle County, Illinois. The licenses provide, among
other things, that they are subject to all rules, regulations, and
orders of the U.S. Nuclear Regulatory Commission (the Commission) now
or hereafter in effect.
II
Section III.A.6(b) of Appendix J to 10 CFR Part 50 states the
following in regard to performing Overall Integrated Containment
Leakage Rate (Type A) Tests (ILRT):
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.
The Type A tests performed during the first, third and fourth
refueling outages for LaSalle County Station, Unit 2, were considered
to be failures in the ``as-found'' condition due to penalties incurred
as a result of leakage measured in Type B and C local leak rate tests
(LLRT). Pursuant to Section III.A.6(b) of Appendix J, Type A testing
was performed during the fifth refueling outage for LaSalle County
Station, Unit 2, in December 1993. That Type A test satisfied the ``as-
found'' acceptance criteria. Section III.A.6(b) of Appendix J requires
an additional Type A test during the sixth refueling outage, currently
scheduled for February 1995, in order to fulfill the condition of two
consecutive successful tests prior to resuming the Type A test interval
of Section III.D.
As an alternative to performing the required Type A test, the
licensee has submitted a Corrective Action Plan to address excessive
local leakage in accordance with the guidance provided in NRC
Information Notice 85-71, ``Containment Integrated Leak Rate Tests,''
dated August 22, 1985. The Corrective Action Plan is in lieu of the
increased test frequency required by Section III.A.6(b) and, therefore,
an exemption from this requirement is needed.
Section III.D.1(a) of Appendix J requires ``* * * 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.'' The last refueling outage for Unit 2 during the first
10-year inservice inspection period is the sixth refueling outage
scheduled for February 1995. Therefore, in addition to the requirements
for additional testing specified in Section III.A.6(b), a Type A test
is required during the upcoming Unit 2 refueling outage as a result of
the periodic retest schedule contained in Section III.D.1(a). To
address the short-term desire not to perform a Type A test during the
sixth refueling outage for Unit 2 and avoid potential future problems,
the licensee has requested an exemption from this requirement such that
future Type A test would not need to coincide with the end of 10-year
inservice inspection periods.
The NRC may grant exemptions from the requirements of the
regulations, pursuant to 10 CFR 50.12, that (1) are authorized by law,
will not present an undue risk to the public health and safety, and are
consistent with the common defense and security; and (2) present
special circumstances. Section 50.12(a)(2) of 10 CFR Part 50 describes
special circumstances as including cases that would not serve the
underlying purpose of the rule or are not necessary to achieve the
underlying purpose of the rule.
III
The underlying purpose of the requirements in Appendix J is to
ensure that containment leakage remains below criteria established to
limit the release of radioactive materials in the event of a design
basis accident. The Type A test is defined in 10 CFR Part 50, Appendix
J, Section II.F, as a ``test 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.'' Containment leakage is measured during the
periodic testing required by Section III.D.1(a) and the additional
testing requirements of Section III.A.6 if the measured leakage exceeds
the established limits. The testing and other requirements contained in
Appendix J ensure that leakage from the containment structure and
penetrations remain below the acceptance criteria.
The licensee conducted four ILRTs during the first 10-year service
period for Unit 1. For Unit 2, ILRTs were performed during the first,
third, fourth, and fifth refueling outages. The Type A test history for
Unit 2 is that the measured leakage rates for Type B and C
penetrations, when added to the measured results from the Type A test,
resulted in an ``as-found'' integrated leakage rate above the
acceptance criteria. These test failures were the direct result of
leakage penalties from Type B and C LLRTs.
Leakage from specific containment penetrations that have been major
contributors to the failure of the integrated leakage rate acceptance
criteria for Unit 2 have been identified. These leakage paths include
isolation valves associated with the drywell equipment and floor drain
sumps, reactor water cleanup suction, transversing incore probe air
purge supply, residual heat removal shutdown cooling return, hydrogen
recombiners, and primary containment chilled water supply. The leakage
associated with the reactor water cleanup suction penetration provided
the overwhelming contribution of local leakage penalty that resulted in
the unsuccessful test during the fourth refueling outage. Leakage
through the various isolation valves has been attributed to causes
[[Page 14469]] such as the introduction of foreign materials,
misapplication of valve types, insufficient seating, defective valve
internals, and failure of valve motor operators. Specific corrective
actions have addressed the above contributors by improving foreign
material exclusion controls, replacing and refurbishing valves,
revising test procedures, and cleaning and lapping seating surfaces.
Overall performance of the identified penetrations has improved
significantly.
In addition to the specific corrective actions taken for the above
isolation valves, the licensee's Corrective Action Plan includes
programmatic changes to limit the leakage occurring from Type C
penetrations. These changes include development and implementation of
an improved trending program to track penetration and valve leakage
rate performance. The improved trending will be designed to help
determine any patterns or groups of valves that demonstrate either good
or poor leakage behavior. Those penetrations determined to be
susceptible to excessive leakage will also be subject to additional
testing requirements beyond that routinely performed during refueling
outages. Identified penetrations will be subject to Type B or C testing
during any non-refueling outage for which a unit is in cold shutdown
for fourteen days or longer. Poorly performing penetrations will also
be reviewed for possible improvements in testing methods as well as
possible repair, modification, or replacement of isolation devices.
As discussed in Information Notice 85-71, the staff has determined
that:
* * * if Type B and C leakage rates constitute an identified
contributor to this failure of the ``as-found'' condition for the
Type A test, the general purpose of maintaining a high degree of
containment integrity might be better served through an improved
maintenance and testing program for containment penetration
boundaries and isolation valves. In this situation, the licensee may
submit a Corrective Action Plan with an alternative leakage test
program proposals 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 test.
The licensee's Corrective Action Plan describes the modification,
testing and preventive maintenance programs implemented or planned to
decrease the leakage from poorly performing isolation devices. The
specific corrective actions performed to date and the programmatic
changes associated with ensuring future performance of penetrations
provide an equivalent degree of assurance that containment integrity
will be maintained as that provided by an additional Type A test
performed on the accelerated frequency specified by Section III.A.6(b)
of Appendix J. The NRC staff concludes that a return to the normal
retest interval of Section III.D of Appendix J is justified and that
the corrective actions taken and the creation of the Corrective Action
Plan for local leak rate testing adequately address the underlying
purpose of the requirements of Appendix J.
In the absence of the additional testing requirements of Section
III.A.6(b), a periodic retest schedule is specified in section
III.D.1(a). This retest schedule requires a minimum of three tests
during a 10-year service period with the third test coinciding with the
10-year plant inservice inspections. LaSalle, Unit 1, completed four
tests during the first ten year interval with the last test coinciding
with the 10-year plant inservice inspections. Due to experiencing Type
A test failures, Unit 2 has performed four tests during the first 10-
year service period and without the requested exemptions would be
required to perform a fifth Type A test during the sixth refueling
outage. The sixth refueling outage for Unit 2 is the last refueling
outage of the 10-year inservice inspection period and, therefore, the
Type A test is required based on the requirements of Section III.D.1(a)
as well as the previously discussed requirements of Section III.A.6(b).
Pursuant to Section II.F of Appendix J, the intent of Type A
testing is ``* * * to measure the primary reactor containment overall
integrated leakage rate * * * at periodic intervals. * * *'' The
licensee has conducted a total of eight ILRTs for LaSalle, Units 1 and
2. The tests conclude that the largest variations in the measured
overall leak rates result from the adjustments required to account for
leakage from Type B and C penetrations. Leakage from sources other than
those covered by Type B and C testing, such as the containment
structure itself, have repeatedly been well below the acceptance
criteria. The requested exemption from Section III.D.1(a) does not
affect the performance of local leak rate testing which would be
expected to detect the most probable sources of containment leakage. As
discussed above, the licensee will not only continue routine Type B and
C testing during each refueling outage, but will also attempt to
minimize local leakage in accordance with their Corrective Action Plan.
The proposed exemption from Section III.D.1(a) does not revise the
expected Type A test interval of between thirty and fifty months which
is derived from the requirement to perform three tests in each ten year
period at approximately equal intervals. For example, Unit 2 performed
a Type A test during the fifth refueling outage in December 1993 and,
with the proposed exemption, will perform another Type A test during
the seventh refueling outage scheduled to begin in late 1996. The
licensee has only proposed to exempt the requirement to perform a Type
A test during the 10-year plant inservice inspections. Given the
continued performance of Type A testing at approximately equal
intervals of forty months and the performance of Type B and C testing
at the required intervals to identify the most probable sources of
containment leakage, the NRC staff finds that performance of Type A
tests coincident with 10-year plant inservice inspections is not
necessary to achieve the underlying purpose of the rule.
On the bases of the above discussions related to Sections
III.A.6(b) and III.D.1(a) of Appendix J, the NRC staff finds that the
licensee has demonstrated that special circumstances are present as
required by 10 CFR 50.12. Further, the staff finds that providing a
one-time exemption of the additional testing requirements of section
III.A.6(b) and an exemption from the requirement to perform a Type A
test coincident with the first 10-year plant inservice inspections
pursuant to Section III.D.1(a) will not present undue risk to the
public health and safety. Although requested as a permanent exemption,
the exemption from the requirements of section III.D.1(a) of Appendix J
related to the third test coinciding with the 10-year plant inservice
inspections has been granted as a one-time exemption for the first 10-
year inservice inspection interval. The exemption is, in effect,
limited to the Type A test planned for the current Unit 2 outage since
Unit 1 has completed the required Type A tests during its first
inservice inspection interval. Future relationships between Appendix J
and inservice inspection intervals can be addressed by anticipated
changes to Appendix J or requests for exemptions from the current
requirements.
IV
Accordingly, the Commission has determined pursuant to 10 CFR
50.12, these exemptions are authorized by law and will not endanger
life or property or the common defense and security and are otherwise
in the public interest. Therefore, the Commission hereby
[[Page 14470]] grants an exemption from the additional testing
requirements of Section III.A.6(b) of Appendix J to 10 CFR Part 50 to
allow the licensee to resume the Type A test interval of Section III.D
for LaSalle, Unit 2, and an exemption from the requirements of Section
III.D.1(a) of Appendix J to allow the licensee to de-couple the Type A
testing and the first 10-year plant inservice inspections for LaSalle,
Unit 2.
Pursuant to 10 CFR 31.32, the Commission determined that the
granting of this exemption will have no significant impact on the
quality of the human environment (60 FR 13187).
Dated at Rockville, Maryland this 10th day of March 1995.
For the Nuclear Regulatory Commission.
Elinor G. Adensam,
Acting Director, Division of Reactor Projects III/IV, Office of Nuclear
Reactor Regulation.
[FR Doc. 95-6616 Filed 3-16-95; 8:45 am]
BILLING CODE 7590-01-M
