[Federal Register Volume 61, Number 72 (Friday, April 12, 1996)]
[Notices]
[Pages 16270-16272]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-9145]
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NUCLEAR REGULATORY COMMISSION
Commonwealth Edison Company (LaSalle County Station, Unit Nos. 1
and 2)
[Docket Nos. 50-373, 50-374]
Exemption
I
The 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
facilities). The licenses provide, among other things, that the
facilities are subject to all rules, regulations, and orders of the
Nuclear Regulatory Commission (the Commission) now or hereafter in
effect.
The facilities consist of two boiling water reactors located at the
licensee's site in LaSalle County, Illinois.
II
Section 50.54(o) of 10 CFR Part 50 requires that primary reactor
containments for water-cooled power reactors meet the leakage rate test
requirements in either Option A or B of Appendix J, to 10 CFR Part 50.
Appendix J, Option B, ``Primary Reactor Containment Leakage Testing for
Water-Cooled Power Reactors,'' contains performance-based requirements,
schedules, and acceptance criteria for tests of the leak tight
integrity of the primary reactor containment and the systems and
components which penetrate the primary containment. The Commission, in
its letter dated March 11, 1996, authorized the licensee to adopt
Option B of Appendix J for the LaSalle Station. Section III.B of
Appendix J, Option B, requires, in part, that leak rate testing must
demonstrate that the sum of the leakage rates at accident pressure
(Pa) of Type B tests, and pathway leakage rates from Type C tests,
is less than the performance criterion (i.e., La) with margin, as
specified in a plant's Technical Specifications (TSs).
The version of Appendix J in effect at the operating license review
stage for the LaSalle Station is now identified as Option A of Appendix
J. Both Options A and B of this appendix implicitly require that the
measured leakage past the inboard and outboard main steamline isolation
valves (MSIVs) be included in the evaluation of the Type B and C tests.
This combination of measured leakages is identified as the combined
local leak rate test results.
When LaSalle was originally licensed, ComEd requested an exemption
from
[[Page 16271]]
this requirement which the staff granted in March 1981. The LaSalle,
Units 1 and 2, Safety Evaluation Report (SER) (NUREG-0519) discusses
the current exemption from 10 CFR Part 50, Appendix J, Option A,
Sections III.C.2(a) and III.C.3, which is based on the conclusions
that: (1) The MSIV leak testing methods for the LaSalle Station were
acceptable alternatives to the cited requirements of Appendix J; and
(2) the measured MSIV leakage rates could be excluded from the
evaluation of the Type B and C tests. These conclusions and their bases
are presented in Section 6.2.6.1 of the LaSalle SER.
Specifically, the LaSalle SER described that in the event of a
loss-of-coolant-accident (LOCA), the LaSalle MSIV leakage control
system (LCS) would maintain a negative pressure between the inboard and
outboard MSIVs and that the effluent from the LCS will be discharged
into the standby gas treatment system (SGTS) in the reactor building
before being released through a stack to the environment. In evaluating
the licensee's requested exemption in the LaSalle SER, the staff based
its decision to grant the exemption on the results of its independent
radiological analysis assuming a TS leak rate limit of 11.5 standard
cubic feet per hour (scfh). This TS limit and the subject exemption
were subsequently modified in Supplement No. 6 to the LaSalle SER
(issued in November 1983) to raise the TS allowable MSIV leakage rate
for each of the four main steamlines to 25 scfh. The subject exemption,
its description, and conditions have remained in force from that time
to the present.
The staff concluded in the LaSalle SER that the LaSalle Station
testing procedure, in which two MSIVs on one steamline are tested
simultaneously using a reduced test pressure of 20.2 pounds per square
inch gage (psig) applied between the inboard and outboard MSIVs, was
also acceptable. The use of this LaSalle MSIV test procedure was
thereby granted as an exemption from certain of the testing
requirements of Appendix J, Option A, to 10 CFR Part 50.
In summary, the staff concluded that the current exemption granted
in March 1981, as modified in November 1983, was acceptable based on:
(1) The method of MSIV testing; (2) a radiological analysis that
assumed a 25 scfh MSIV leak rate for each of the four main steamlines
and whose radiological consequences for all primary containment leakage
were within the radiation exposure guidelines of 10 CFR Part 100 and
met the requirements of 10 CFR Part 50, Appendix A, General Design
Crierion (GDC) 19; and (3) the licensee's commitment to periodically
test the MSIVs to ensure that the measured MSIV leakage did not exceed
the TS allowable MSIV leakage rates.
The deletion of the MSIV LCS and use of an alternate leakage
treatment (ALT) pathway (i.e., the main steamlines, the steam
drainlines and the main condenser) as proposed in the licensee's letter
dated August 28, 1995, as well as the licensee's proposal to raise the
TS allowable MSIV leak rates, affects the description of one part of
the subject exemption; i.e., that part which allows the exclusion of
the measured leakage from the evaluation of the combined local leak
rate test results. Accordingly, the licensee requested in its letter
dated August 28, 1995, as supplemented in its letter dated March 4,
1996, a modification to part of the subject exemption from the
Commission's regulations in Appendix J. The proposed modification to
the subject exemption is from the requirements of 10 CFR Part 50,
Appendix J, Option B, Section III.B. which would allow the licensee to
(1) continue using a reduced test pressure for the leakage testing of
the MSIVs, and (2) continue to exclude the measured MSIV leakage from
the combined local leak rate test results.
The licensee also submitted in its letter dated August 28, 1995, a
request for license amendments for the LaSalle Station in conjunction
with the proposed modification of the existing exemption. The proposed
license amendment would revise the LaSalle TSs to reflect the deletion
of the MSIV LCS, utilize an ALT pathway and raise the TS allowable MSIV
leakage. This proposal is based on the Boiling Water Reactor Owners
Group (BWROG) method summarized in General Electric Report NEDC-31858P,
Revision 2, ``BWROG Report for Increasing MSIV Leakage Rate Limits and
Elimination of Leakage Control System,'' dated September 1993. When the
license amendments are granted, part of the original exemption from the
Appendix J leakage test requirements will not be applicable because the
description and conditions of the original exemption will be
significantly altered.
An important element in the evaluation of the licensee's request to
delete the MSIV LCS is whether the components of the proposed ALT
pathway for MSIV leakage remain functional under design basis accident
(DBA) conditions. In this regard, the staff reviewed the capability of
the ALT pathway to withstand the seismic loads resulting from a safe
shutdown earthquake (SSE) and remain functional. The staff's review of
this aspect found that there was sufficient margin in all ALT
components against gross failure under SSE conditions. Further, the
staff found that the two redundant paths leading from the MSIVs to the
main condenser provided an acceptable level of reliability for the
proposed ALT pathway. Finally, the staff found that motor operated
valves which define the boundaries of the ALT pathway either have: (1)
reliable power sources; (2) will remain in their required open or
closed position; or (3) will be administratively controlled. On this
basis, the staff found that the proposed ALT pathway would remain
functional under DBA conditions.
The staff performed an independent assessment of the radiological
consequences of the licensee's proposal to delete the present LCS and
establish an ALT pathway to control and process the leakage past the
MSIVs as well as the licensee's proposal to increase the TS allowable
MSIV leakage rate. This radiation dose assessment evaluated the effect
of the proposed hardware modifications and TS revisions separately and
then combined these doses with those resulting from all other leakages
from the LaSalle primary containment. The staff found in its
radiological assessment of the proposed modification of the existing
exemption that the potential offsite and control room doses to
personnel remain within the applicable criteria of 10 CFR Part 50,
Appendix A, GDC-19 and 10 CFR Part 100 and is consistent with the
guidance in Standard Review Plan (SRP) Section 6.4.
The proposed hardware and TS changes associated with deletion of
the MSIV LCS do not affect the bases for part of the current exemption.
The modification and implementation of the TS change requests will not
alter the procedure for MSIV testing (i.e., the test may be performed
at a minimum pressure of 20.2 psig applied between the inboard and
outboard MSIVs). Furthermore, when Option B was added to Appendix J in
September 1995 (60 FR 49495 (1995)), this version stated in Section
V.B.1 that specific exemptions to Option A that have been formally
approved by the NRC, are still applicable. On this basis, the staff
finds that the portion of the existing exemption (i.e., the application
of test pressure to its MSIVs) remains in force and no further
consideration is required for this portion of the subject exemption
request.
As part of its evaluation of the TS change to delete the MSIV LCS,
the NRC staff concluded that there is reasonable assurance that: (1)
the current MSIV leak testing method (i.e., a minimum
[[Page 16272]]
test pressure of 20.2 psig applied between the inboard and outboard
MSIVs) is an acceptable method for testing MSIV leakage; (2) the
proposed MSIV leakage ALT pathway will withstand the seismic loads from
an SSE and remain functional; and (3) the calculated radiation doses
assuming an MSIV leakage rate limit of 100 scfh per main steamline, not
to exceed 400 scfh for all four main steamlines, are within the
radiation exposure guidelines in 10 CFR Part 100, meet the requirements
of GDC-19 of Appendix A to 10 CFR Part 50 and are consistent with SRP
Section 6.4. On this basis, the staff finds it acceptable to continue
to exempt LaSalle, Units 1 and 2, from the 10 CFR Part 50, Appendix J,
Option B, requirements to include the measured MSIV leakage rate from
the combined local rate tests since the radiological consequences of
the MSIV leakage are acceptable and continue to meet the underlying
intent of the rule. Therefore, the staff finds that the requested
modification to the existing exemption in the licensee's submittal
dated August 28, 1995, as supplemented on March 4, 1996, may be
granted.
III
Pursuant to 10 CFR 50.12, the Commission may, upon application by
any interested person or upon its own initiative, grant exemptions from
the requirements of 10 CFR Part 50 when: (1) the exemptions are
authorized by law, will not present an undue risk to public health and
safety, and are consistent with the common defense and security; and
(2) when special circumstances are present. Special circumstances are
present whenever, according to 10 CFR 50.12(a)(2)(ii), ``Application of
the regulation in the particular circumstances would not serve the
underlying purpose of the rule or is not necessary to achieve the
underlying purpose of the rule * * * .''
The underlying purpose of the rule is to assure leakage through the
primary reactor containment, and systems and components penetrating
primary containment do not exceed allowable leakage rate values and
that periodic surveillance is performed so that proper maintenance and
repair are made. The staff analysis has demonstrated that an adequate
margin can be maintained even if leakage past the MSIVs through the ALT
pathway occurs at the TS allowable MSIV leakage rates of 100 scfh for
each main steamline, not to exceed a total of 400 scfh for all four
main steamlines.
IV
Accordingly, the Commission has determined that, pursuant to
Section 50.12 of 10 CFR Part 50, an exemption is authorized by law and
will not present an undue risk to public health and safety, and that
there are special circumstances present, as specified in 10 CFR
50.12(a)(2). An exemption is hereby granted from the requirements of
Sections III.B, of Appendix J, Option B, to 10 CFR Part 50 regarding
testing the MSIVs at accident pressure and including MSIV leakage rates
in the sum of the Type B and C leakage rates. The exemption allows: (1)
leakage testing of the MSIVs using a minimum test pressure of 20.2 psig
applied between MSIVs and a TS leakage rate limit of 100 scfh per main
steamline past the MSIVs, not to exceed 400 scfh for all four main
steamlines; and (2) exclusion of the measured MSIV leakage rate from
the evaluation of the combined local leak rate tests.
Pursuant to 10 CFR 51.32, the Commission has determined that the
granting of this exemption will have no significant impact on the
quality of the human environment (61 FR 14837).
This exemption is effective upon issuance and will be implemented
prior to startup of LaSalle, Unit 1, from its present refueling outage
and implemented for LaSalle, Unit 2, prior to startup from its
refueling outage scheduled to start in September 1996.
For the Nuclear Regulatory Commission.
Dated at Rockville, Maryland, this 5th day of April 1996.
Jack W. Roe,
Director, Division of Reactor Projects--III/IV, Office of Nuclear
Reactor Regulation.
[FR Doc. 96-9145 Filed 4-11-96; 8:45 am]
BILLING CODE 7590-01-P
