[Federal Register Volume 59, Number 2 (Tuesday, January 4, 1994)]
[Notices]
[Pages 333-335]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 93-54]
[[Page Unknown]]
[Federal Register: January 4, 1994]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-338 and 50-339]
Virginia Electric and Power Company (North Anna Power Station,
Units No. 1 and No. 2)
Exemption
I
Virginia Electric and Power Company (the licensee) is the holder of
Facility Operating License Nos. NPF-4 and NPF-7 which authorize
operation of North Anna Power Station, Units No. 1 and No. 2 (NA-1&2,
the facility) at steady-state power levels not in excess of 2893
megawatts thermal. The licenses provide, among other things, that the
facility is subject to all the rules, regulations, and orders of the
Nuclear Regulatory Commission (the Commission) now or hereafter in
effect.
The facility employs pressurized water reactors (PWRs) located at
the licensee's site in Louisa County, Virginia.
The licensee is implementing a refurbishment and restoration
program for the NA-1&2 service water system (SWS). The program is being
conducted in several stages. The subject Phase 1, Stage 4 is to be
conducted for a period of time beginning January 3, 1994 and ending
October 13, 1994, and will be performed during dual unit operating
conditions. The scope of Stage 4 involves restoration of the two 24-
inch auxiliary supply lines from Lake Anna to the main SW headers. This
consists of approximately 900 linear feet of piping (450 feet per
line). Each 450-foot line consists of approximately 185 feet of direct
buried piping, 230 feet of concrete-encased piping and 35 feet of
exposed piping. To support the Phase 1, Stage 4 SWS restoration
program, the licensee has identified one temporary exemption required
at this time. The exemption is specified below.
II
The Code of Federal Regulations at 10 CFR part 50, Appendix A,
General Design Criterion-2 (GDC-2) requires that: Structures, systems,
and components important to safety shall be designed to withstand the
effects of natural phenomena such as * * * tornadoes, * * * without
loss of capability to perform their safety functions.
The licensee has requested the temporary exemption from GDC-2
because of planned maintenance which will expose portions of the SWS
piping to the potential effects of postulated missiles generated by
natural phenomena. Earth and concrete protect the piping systems from
the effects of severe weather events at the NA-1&2 site, such as
tornadoes, for conformance with the requirements of GDC-2. The
excavation of the auxiliary service water lines will affect only the
missile shield protection aspects of GDC-2, with seismic qualification
being retained. While producing a minimal increase in missile
interaction risk, excavation of the piping does not result in total
vulnerability to missiles. In the area of the planned excavation, the
lines are substantially below grade and are adjacent to the turbine
building structure. This will prevent some lateral aspects of missile
vulnerability.
The licensee is providing contingency measures with compensatory
actions to provide added assurance of safe operation of the facility
during the exemption period. Although the exemption is requested only
for missile protection, the risk to the plant due to construction
mishaps is more significant than the risk due to natural phenomena.
Therefore, the compensatory measures are geared toward preventing such
mishaps in addition to minimizing the potential for missiles generated
by severe weather. As stated in the staff's Safety Evaluation dated
December 27, 1993, these compensatory actions include but are not
limited to the following:
Electronic scanning and nondestructive locating methods
will be used to accurately determine underground locations of piping,
duct banks, and other buried utilities prior to excavation.
Machine excavation will be limited to an elevation that
does not pose a threat to the auxiliary service water (ASW) lines. The
remaining excavation will be performed by hand operated power and
manual tools.
Physical barriers will be used to keep vehicles a safe
distance from the excavation site.
Loose materials in and around the excavation will be
limited to only those absolutely necessary for activities in progress.
Lifting and rigging components will be inspected and load
tested. Lifting of equipment or construction materials over the
excavation will be performed with adequate precautions in accordance
with approved procedures.
Direct verbal communication (using dedicated radios if
necessary) will be maintained between equipment operators and
supervisors/observers.
Operable ASW lines will retain their seismic
qualification.
Engineering reviews will be performed for shoring and
temporary supports (if required) in the excavation area.
Gasoline powered equipment will be refilled using small
containers and the number of containers within the excavation area will
be restricted. This is in accordance with the existing station
procedures.
Worker training and shift briefings will be conducted for
all aspects of the project.
Severe weather procedures will be used to provide
notification to clear the area of vehicles and loose materials in the
event of a tornado watch or other high wind conditions.
Adequate wind protection and heating will be provided
during freezing weather conditions.
Considering the existing design features and compensatory measures
proposed by the licensee, the likelihood of damage to the exposed
auxiliary SWS lines from postulated missiles generated by natural
phenomena is minimal. Also, based on the compensatory measures
provided, assurance exists that the ability to bring the plant to a
safe shutdown will be maintained following any natural phenomena,
including tornadoes or other severe weather which could result in
airborne missiles. Therefore, there is reasonable assurance that the
proposed GDC-2 exemption will present no undue risk to public health
and safety.
III
The Commission has determined, pursuant to 10 CFR 50.12(a), that
special circumstances as set forth in 10 CFR 50.12(a)(2)(v). The
exemption would provide only temporary relief from the applicable
regulation (GDC-2). The exemption is requested for a specific time
period after which the facility would again be in conformance with all
the requirements of GDC-2. The licensee has made good faith efforts in
considering alternatives to the exemption requests and has concluded
that the Phase 1, Stage 4 SWS refurbishment and restoration program can
only be conducted without the subject exemption during a period when
both NA-1&2 are shut down and defueled. The impact of scheduling such a
dual-unit outage would have significant consequences in terms of power
supply, fuel storage, capacity, and replacement power costs. Finally,
the exemption will indirectly result in benefits to the public from
increased reliability of the upgraded safety-related SWS.
Based on the above and on review of the licensee's submittal, as
summarized in the Safety Evaluation dated December 27, 1993, the NRC
staff concludes that the likelihood of unacceptable damage to the
exposed auxiliary SW lines due to tornadoe-borne missiles during the
exemption period is low.
Based on the low probability of unacceptable events, coupled with
the comprehensive compensatory measures which the licensee has
committed to, the NRC staff finds the proposed exemption from GEDC-2
acceptable.
IV
Accordingly, the Commission has determined that, pursuant to 10 CFR
50.12, the subject 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)(v), are
present justifying the exemption; namely, that the exemption would
provide only temporary relief from the applicable regulations and that
the licensee has made good faith efforts to comply with the
regulations.
Therefore, the Commission hereby approves the following exemption:
NA-1&2 may operate without conforming to the requirements of GDC-2 as
they apply to the buried portions of the auxiliary SWS lines from Lake
Anna to the main SWS header providing that compensatory measures as
described herein are continued for the period of the exemption.
Pursuant to 10 CFR 51.32, the Commission has determined that
granting the above exemption will have no significant impact on the
quality of the human environment (October 7, 1993, 58 FR 52332).
The subject Phase 1, Stage 4 SWS GDC-2 exemption is effective from
its date of issuance through October 14, 1994.
Dated at Rockville, Maryland this 27th day of December 1993.
For the Nuclear Regulatory Commission.
Gus C. Lainas,
Acting Director, Division of Reactor Projects--I/II, Office of Nuclear
Reactor Regulation.
[FR Doc. 93-54 Filed 1-3-94; 8:45 am]
BILLING CODE 7590-01-M