[Federal Register Volume 64, Number 2 (Tuesday, January 5, 1999)]
[Notices]
[Page 534]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-99]
[[Page 534]]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-413 and 50-414]
Duke Energy Corporation, et al., (Catawba Nuclear Station, Units
1 and 2); Exemption
I
Duke Energy Corporation, et al. (the licensee) is the holder of
Facility Operating License Nos. NPF-35 and NPF-52, for the Catawba
Nuclear Station (CNS), Units 1 and 2. The licenses provide, among other
things, that the licensee is subject to all rules, regulations, and
orders of the Commission now or hereafter in effect.
These facilities consist of two pressurized water reactors located
at the licensee's site in York County, South Carolina.
II
Title 10 of the Code of Federal Regulations (10 CFR), Part 50,
Appendix A, specifies general design criteria for nuclear power plants.
General Design Criterion (GDC) 57, regarding closed system isolation
valves, states:
Each line that penetrates primary reactor containment and is
neither part of the reactor coolant pressure boundary nor connected
directly to the containment atmosphere shall have at least one
containment isolation valve which shall be either automatic, or
locked closed, or capable of remote manual operation. This valve
shall be outside containment and located as close to the containment
as practical. A simple check valve may not be used as the automatic
isolation valve.
The Commission may grant an exemption from the requirements of the
regulations pursuant to 10 CFR 50.12 if the 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
will not consider granting an exemption unless special circumstances
are present. Special circumstances are considered to be present under
10 CFR 50.12(a)(2) where application of the regulation in the
particular circumstances conflicts with other rules or requirements of
the Commission or where application of the regulation would not serve
the underlying purpose of the rule or is not necessary to achieve the
underlying purpose of the rule.
III
By letter dated September 2, 1997, the licensee requested an
exemption from GDC-57 for Containment Penetrations M261 and M393, which
are main steam penetrations. These lines penetrate the containment and
are not part of the reactor coolant pressure boundary, nor are they
connected directly to the containment atmosphere. Outside of the
containment, these lines branch into various separate, individual lines
before reaching the respective main steam isolation valves. From each
of these main steam lines, one branch supplies main steam to the
turbine-driven auxiliary feedwater pump (CAPT, using the licensee's
abbreviation).
Valves SA-1 and SA-4 are manual gate valves located in the Interior
Doghouse immediately downstream of the respective main steam piping.
These valves are locked open (with breakaway locks) and are only
capable of local manual operation. These valves are required to be open
by the Technical Specifications (TS) in order to supply steam to the
CAPT, which is part of the engineered safety features. From a
probabilistic risk assessment perspective, the CAPT is one of the most
risk-significant safety system components. Adding motor operators to
SA-1 and SA-4, so that they become automatic or capable of remote
operation (i.e., meeting GDC-57) would, thus, degrade the reliability
of the CAPT to mitigate an accident because the motor operators would
introduce a new failure mode. Keeping SA-1 and SA-4 closed (i.e.,
meeting GDC-57) during plant operation would violate a TS requirement.
Valves SA-1 and SA-4 can be manually closed, as needed during
certain accidents, to isolate the steam lines they serve. If SA-1 and
SA-4 are inaccessible due to post-accident environmental conditions,
the associated stop check valves can be used to isolate these steam
lines. The licensee stated that the amount of time needed by operators
to isolate steam using SA-1 and SA-4, or their associated stop check
valves, has been factored into the accident analyses and resultant dose
calculations in the Updated Final Safety Analysis Report.
Thus, as stated in the staff's safety evaluation, modifying valves
SA-1 and SA-4 so that they can meet the operational requirement
specified by GDC-57 would reduce the reliability of the CAPT, violate
an existing TS, or both. The time needed by operators to manually close
SA-1 and SA-4, or their associated stop check valves, during an
accident, has been factored into accident analyses and is bounded by
the design-basis accident scenarios and consequences. On such bases,
the staff concludes that literal compliance with the operational aspect
of GDC-57 is not desirable and the proposed exemption is acceptable.
IV
Accordingly, the Commission has determined that special
circumstances are present as defined in 10 CFR 50.12(a)(2)(ii).
Specifically, the Commission finds that application of GDC-57 with
respect to Valves SA-1 and SA-4 conflicts with existing TS and is not
necessary to achieve the underlying purpose of the rule. The underlying
purpose of GDC-57 is to ensure that reliable means exist to isolate
this type of line when isolation is needed. As previously discussed,
Valves SA-1 and SA-4 can be manually closed to isolate their respective
steam lines. Thus, the design of these valves and the existence of
appropriate procedures for manually closing these valves provide a
reliable method of isolating the steam lines when needed. The
Commission hereby grants the licensee an exemption from the requirement
of 10 CFR Part 50, Appendix A, GDC-57. Specifically, this exempts the
licensee from having to lock close Valves SA-1 and SA-4 against TS
requirements, or having to so modify them that they become automatic,
or are capable of remote manual operation.
Pursuant to 10 CFR 51.32, the Commission has determined that
granting of this exemption will have no significant effect on the
quality of the human environment (63 FR 71659, dated December 29,
1998).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 29th day of December 1998.
For the Nuclear Regulatory Commission.
Brian W. Sheron,
Acting Director, Office of Nuclear Reactor Regulation.
[FR Doc. 99-99 Filed 1-4-99; 8:45 am]
BILLING CODE 7590-01-P
