[Federal Register Volume 60, Number 116 (Friday, June 16, 1995)]
[Notices]
[Pages 31737-31738]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-14791]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-499]
Exemption
In the Matter of Houston Lighting & Power Company, City Public
Service Board of San Antonio, City of Austin, Texas; (South Texas
Project, Unit 2).
I
Houston Lighting & Power Company, (the licensee) is the holder of
Facility Operating License No. NPF-80, which authorizes operation of
the South Texas Project, Unit 2. The operating license provides, among
other things, that the licensee is subject to all rules, regulations,
and orders of the Commission now and hereafter in effect.
The facility consists of a pressurized water reactor at the
licensee's site in Matagorda County, Texas.
II
Section III.D.1.(a) of Appendix J to 10 CFR Part 50 requires the
performance of three Type A containment integrated leakage rate tests.
(CILRTs), 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 inspection.
III
By letter dated March 16, 1995, Houston Lighting & Power requested
relief from the requirement to perform a set of three Type A tests at
approximately equal intervals during each 10-year service period. The
requested exemption would permit an interval extension for the second
Type A test of approximately 18 months (from the currently scheduled
outage, Fall 1995, until the next planned refueling outage, Spring
1997). This request does not alter the requirement that the third Type
A test shall be conducted when the plant is shutdown for the 10-year
plant inservice inspection.
The licensee's request cites the special circumstances of 10 CFR
50.12, paragraph (a)(2)(ii), as the basis for the exemption. The
underlying purpose of the requirement to perform three Type A CILRTs,
at approximately equal intervals during each 10-year service period, is
to assure that leakage through the primary reactor containment is
detected and does not exceed allowable leakage rate values. The
licensee has stated that the existing Type B and C local leak rate test
(LLRT) programs are not being modified by this request, and will
continue to effectively detect containment leakage caused by the
degradation of active containment isolation components as well as
containment penetrations. It has been the consistent and uniform
experience at South Texas during the two Type A tests conducted in 1988
(the pre-operational Type A test) and 1991 (the first periodic Type A
test), that any significant containment leakage paths are detected by
the Type B and C testing. The Type A test results have only been
confirmatory of the results of the Type B and C test results.
Therefore, consistent with 10 CFR 50.12, paragraph (a)(2)(ii),
application of the regulation in this particular circumstance is not
necessary to achieve the underlying purpose of the rule.
IV
Section III.D.1.(a) of Appendix J to 10 CFR part 50 states that a
set of three Type A leakage rate tests shall be performed at
approximately equal intervals during each 10-year service period.
The licensee proposes an exemption to this section which would
provide an interval extension for the Type A test by approximately 18
months. The Commission has determined that pursuant to 10 CFR
50.12(a)(1) that this exemption is authorized by law, will not present
an undue risk to the public health and safety, and is consistent with
the common defense and security. The Commission further determines that
special circumstances, as provided in 10 CFR 50.12(a)(2)(ii), are
present justifying the exemption; namely, that application of the
regulation in this particular circumstance is not necessary to achieve
the underlying purpose of the rule.
The NRC staff has reviewed the basis and supporting information
provided by the licensee in the exemption request. The NRC staff has
noted that the licensee has a good record of ensuring a leak-tight
containment. Both previous Type A tests were within the acceptance
limits, and both passed with significant margin. In addition, at the
staff's request, the licensee has verbally committed to perform the
general containment inspection specified in Section V.A of appendix J
even though this inspection is only required prior to a Type A test.
The NRC staff has also made use of a draft staff report, NUREG-
1493, which provides the technical justification for the present
Appendix J rulemaking effort which also includes a 10-year test
interval for Type A tests. The integrated leakage rate test, or Type A
test, measures overall containment leakage. However, operating
experience with all types of containments used in this country
demonstrates that essentially all containment leakage can be detected
by local leakage rate tests (Type B and C). According to results given,
in NUREG-1493, out of 180 ILRT reports covering 110 individual reactors
and approximately 770 years of operating history, only about 3% of
leakage that exceeds current requirements is detectable only by CILRTs,
and those few failures were only marginally above prescribed limits.
This study agrees well with previous NRC staff studies which show that
Type B and C testing can detect a very large percentage of containment
leaks. The South Texas Project, Unit 2 experience has also been
consistent with this.
The Nuclear management and Resources Council (NUMARC), now the
Nuclear Energy Institute (NEI), collected and provided the NRC staff
with summaries of data to assist in the Appendix J rulemaking effort.
NUMARC collected results of 144 ILRTs from 33 units; 23 ILRTs exceeded
1.0La. Of these, only nine were not due to Type B or C leakage
penalties. The NEI data also added another perspective. The NEI data
show that in about one-third of the cases exceeding allowable leakage,
the as-found leakage was less than 2La; in one case the as-found
leakage was less than 3La; one case approached 10La; and
[[Page 31738]]
in one case the leakage was found to be approximately 21La. For
about half of the failed ILRTs the as-found leakage was not quantified.
These data show that, for those ILRTs for which the leakage was
quantified, the leakage values are small in comparison to the leakage
value at which the risk to the public starts to increase over the value
of risk corresponding to La (approximately 200La, as
discussed in NUREG-1493).
Based on generic and plant-specific data, the NRC staff finds the
basis for the licensee's proposed exemption to allow a one-time
exemption to permit a schedular extension of one cycle for the
performance of the Appendix J Type A test to be acceptable.
Pursuant to 10 CFR 51.32, the Commission has determined that
granting this Exemption will not have a significant impact on the
environment (60 FR 28431).
This Exemption is effective upon issuance and shall expire at the
completion of the 1997 refueling outage.
Dated at Rockville, Maryland, this 9th day of June 1995.
For the Nuclear Regulatory Commission.
John N. Hannon,
Acting Deputy Director, Division of Reactor Projects--III/IV, Office of
Nuclear Reactor Regulation.
[FR Doc. 95-14791 Filed 6-15-95; 8:45 am]
BILLING CODE 7590-01-M
