[Federal Register Volume 69, Number 159 (Wednesday, August 18, 2004)]
[Notices]
[Pages 51334-51336]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-18885]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-263]
Nuclear Management Company, LLC; Monticello Nuclear Generating
Plant; Exemption
1.0 Background
The Nuclear Management Company, LLC (NMC) is the holder of Facility
Operating License No. DPR-22, which authorizes operation of the
Monticello Nuclear Generating Plant (MNGP). NMC provides, among other
things, that the facility is subject to all rules, regulations, and
orders of the U.S. Nuclear Regulatory Commission (NRC, the Commission)
now or hereafter in effect. The facility consists of a boiling-water
reactor located in Wright County, Minnesota.
2.0 Request/Action
Title 10 of the Code of Federal Regulations (10 CFR), Section
50.48(b), ``Fire Protection,'' specifies that Appendix R, ``Fire
Protection Program for Nuclear Power Facilities Operating Prior to
January 1, 1979,'' established fire protection requirements to satisfy
10 CFR Part 50, Appendix A, General Design Criterion 3, ``Fire
Protection.'' Appendix R, Section III.G.2.b, specifies that (1) Cables
and equipment and associated non-safety circuits of redundant trains be
separated by a horizontal distance of more than 20 feet with no
intervening combustible or fire hazards, and (2) fire detectors and an
automatic fire suppression system be installed in the fire area.
In Northern States Power's (the licensee for Monticello at that
time) letter of June 30, 1982, it requested a permanent exemption from
the automatic suppression system requirements of Appendix R, Section
III.G.2.b for the suppression pool torus area. Northern States Power
justified the exemption by stating the following:
* * * the area is separated from other plant areas by three-hour
fire rated barriers. Fire protection consists of smoke detectors,
manual hose stations, and portable fire extinguishers. The only
redundant safe shutdown equipment in the area consists of
instrumentation for measuring the water temperature and level in the
torus. The redundant trains are separated by one hundred feet and
are free of intervening combustibles. Essentially no combustible
material is stored or located in the area. Furthermore, all surfaces
are concrete except for the torus, which is steel. All cables are
installed in conduit.
The technical requirements of Section III.G.2 were not met in fire
zone 1F (the torus compartment at MNGP) because cables and components
of redundant shutdown divisions were not protected with area-wide
automatic sprinkler system.
The NRC's letter of June 16, 1983, granted the exemption request,
citing the following:
* * * because of the restricted access to this area, the
probability of an exposure fire from the accumulation of transient
combustibles, during normal operation, is low. We find that this
feature, in conjunction with the one hundred feet of separation
between redundant trains and early warning fire detection, provides
reasonable assurance that one train will be maintained free of fire
damage.
NMC's letter of September 15, 2003, as supplemented February 24,
2004, resubmitted its request for a permanent exemption from the
requirements of Section III.G.2.b for fire area IV/fire zone 1F,
stating the following:
* * * in 1985, a new safe shutdown analysis crediting only the
minimum systems and equipment required to achieve safe shutdown was
developed. This new shutdown methodology required the use of Core
Spray, Safety Relief Valves and Residual Heat Removal (RHR) in the
Suppression Pool Cooling mode. Prior to that time, these systems
were not required to achieve safe shutdown given a fire in Fire Area
IV/Fire
[[Page 51335]]
Zone 1F. Both Division I and Division II components and cables for
the Core Spray and Residual Heat Removal systems are contained
within this fire area. Only one division of Safety Relief Valve
control and indicating cables is located with this fire area. The
impact of this revised shutdown methodology on the Fire Area IV/Fire
Zone 1F exemption was not addressed when the shutdown model was
revised. In addition, the Division II suppression pool temperature
cable exit from the Torus Compartment and the location of the
Division II suppression pool level transmitter were incorrectly
depicted in Enclosure 2 of Reference G.2.
* * * As a result of internal assessments of the MNGP Fire
Protection Program, NMC determined that the existing exemption from
10 CFR 50, Appendix R, Section III.G.2.b for the Torus Compartment *
* * did not bound the existing plant configuration and the current
MNGP Appendix R Safe Shutdown Analysis. The NMC has completed an
investigation into the Torus Compartment design basis and has
determined that an exemption is appropriate for this area.
The results of the NRC staff's evaluation of NMC's request are
provided below.
3.0 Discussion
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 exist
if it is not necessary to apply the technical requirements of 10 CFR
Part 50 to achieve the underlying purpose of the regulation. The
underlying purpose of Appendix R, Section III.G.2.b to 10 CFR Part 50
is to assure that one train of redundant safe shutdown equipment will
be maintained free of fire damage.
The NRC staff analyzed the following items in the suppression pool
torus area at MNGP to satisfy the requirements of 10 CFR 50.12 for
granting the exemption from the automatic suppression system
requirements of Appendix R, Section III.G.2.b:
Minimal amount of fixed and transient combustibles
Smoke detector provisions
Existing separation between redundant trains of core spray
valves, RHR cooling valves, suppression pool level transmitters, and
the suppression pool temperature monitoring system (SPOTMOS).
NMC's letter of September 15, 2003, stated that fixed combustibles
consist of a single \3/4\-inch diameter radiax antenna cable, routed
around approximately 70 percent of the perimeter wall. Other cables
within the torus compartment are in conduit except for short runs of
exposed cable that may exist between a device and its associated
junction box or conduit. This amount of fixed combustibles is
negligible. NMC also said that transient combustibles were controlled
by procedure.
The NRC staff sent NMC a request for additional information (RAI)
dated January 30, 2004, asking NMC to clarify the type and quantity of
transient combustibles it allowed into fire zone 1F. NMC's RAI response
letter of February 24, 2004, disclosed the transient combustible
loading for fire zone 1F. The loading consisted of two gallons of
general-purpose solvent and three fiberglass ladders for a total of 1.7
million British thermal units (BTUs) equating to 142 BTUs per square
foot. NMC evaluated additional combustibles for outage pre-staging that
have been in the fire zone and totaled them to be 2.4 million BTUs.
This is less than 1100 BTUs per square foot. These amounts of transient
combustibles are minimal.
The arrangement of the core spray valves is shown on Figure 1 of
NMC's September 15, 2003, submittal. Division 1 core spray valve MO-
1749 is located just below the ceiling of the torus compartment near
column lines N and 8.9. Division 2 core spray valve MO-1750 is located
in the same compartment near column lines N and 3.1. Approximately 130
feet separate these valves and their associated cables. The drywell
also blocks the direct line-of-sight. Smoke detectors, that are
annunciated in the control room, are near each core spray valve with
three more detectors intervening on each of the two paths around the
torus compartment.
The arrangement of the RHR cooling valves is also shown on Figure 1
of NMC's submittal. Division 1 RHR cooling valves MO-2006 and MO-2008
are located in the torus compartment between column lines N and P and
7.9. Division 2 RHR cooling valve MO-2009 is located in the same
compartment between column lines N and P and 4.1 and 5.1. Approximately
130 feet separate the Division 1 valves and their associated cables
from the Division 2 valves. The drywell also blocks the direct line-of-
sight. Smoke detectors, that are annunciated in the control room, are
near each RHR cooling valve with three more detectors intervening on
each of the two paths around the torus compartment.
As previously discussed in Section 2.0 of this evaluation, the
NRC's letter of June 16, 1983, granted an exemption for the suppression
pool level transmitters. However, during the NRC staff's evaluation of
NMC's September 15, 2003, exemption request, the staff identified
discrepancies between Figures 1 and 2 concerning the routing of conduit
for Division 1 and Division 2 suppression pool level transmitters
LT7338A and LT338B. The NRC's RAI of January 30, 2004, questioned the
location of the conduit and the associated penetrations exiting the
fire zone. NMC's RAI response corrected the location and placed all of
the information on Figure 2 of the revised submittal. Division 1 and
Division 2 components are separated by at least 75 feet. Smoke
detectors that are annunciated in the control room are near each level
transmitter, with additional detectors intervening between the
divisions in the torus compartment.
The SPOTMOS at MNGP consists of two redundant divisions. Each of
the divisions has eight resistance temperature detectors (RTDs).
Cabling inside conduit connects the RTDs in each division, runs around
the suppression pool in close proximity to each other, and then exits
the fire zones at least 75 feet apart. NMC's letter of September 15,
2003, stated that the system could operate in an ``operable but
degraded'' mode to support post-fire safe shutdown with as little as
one detector in one train being operable.
Due to the close proximity of the conduits, and the concern that a
single fire could involve both Division 1 and Division 2 conduits, the
NRC staff requested further information on the SPOTMOS in its RAI.
Specifically, the NRC staff requested NMC to address how the SPOTMOS
would automatically eliminate (1) a failed temperature sensor, and (2)
a fire-induced failure (hot short, short to ground, open, or increased/
decreased resistance or voltage) of the cable to the temperature
elements that is inside conduit. NMC's RAI response of February 24,
2004, described the operation of the system, addressing each of the
failure modes. The critical distance between Division 1 and Division 2
for operation in the operable-but-degraded mode is at least 85 feet
(where the cables enter the torus compartment). Smoke detectors, that
annunciate in the control room, are located near each cable entry.
Additional smoke detectors are distributed throughout the torus
compartment.
The NRC staff concludes that NMC has met the underlying purpose of
Appendix R, Section III.G.2.b, without having an automatic fire
suppression system in the suppression pool torus area at MNGP
considering the following:
[[Page 51336]]
Minimal amount of fixed and transient combustibles present
Smoke detector provisions
Separation between redundant trains of core spray valves,
RHR cooling valves, and suppression pool level transmitters
Ability of SPOTMOS to continue to operate with at least
one RTD on one train in the operable-but-degraded mode for any fire in
fire zone 1F that involved both conduit trains
The NRC staff further concludes that pursuant to 10 CFR
50.12(a)(2)(ii), application of the regulation in these particular
circumstances is not necessary to achieve the underlying purpose of the
rule. Therefore, NMC's exemption request is acceptable.
4.0 Conclusion
Accordingly, the Commission has determined that, pursuant to 10 CFR
50.12(a), 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. Also, special circumstances are present.
Therefore, the Commission hereby grants NMC a permanent exemption from
the requirements of 10 CFR Part 50, Appendix R, Section III.G.2.b, to
not provide an automatic fire suppression system for fire area IV/fire
zone 1F at MNGP.
Pursuant to 10 CFR 51.32, the Commission has determined that the
granting of this exemption will not have a significant effect on the
quality of the human environment (69 FR 46187).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 6th day of August 2004.
For the Nuclear Regulatory Commission.
Ledyard B. Marsh,
Director, Division of Licensing Project Management, Office of Nuclear
Reactor Regulation.
[FR Doc. 04-18885 Filed 8-17-04; 8:45 am]
BILLING CODE 7590-01-P