HomeMy WebLinkAbout841143.tiff ``Eaa a`CNe UNITED STATES
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W ' NUCLEAR REGULATORY COMMISSION
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REGION IV
0tb, 4. , r," 611 RYAN PLAZA DRIVE, SUITE 1000
a° ARLINGTON, TEXAS 76011
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June 4, 1984 DlF'? „ .,
Docket No. : 50-267
Mr. O.R. Lee, Vice President JUN
Electric Production 7198
Public service Company of Colorado
P.O. Box 840
Denver, Colorado 80201
Dear Mr. Lee:
During a meeting in the Region IV Offices on April 27, 1984, between
members of your staff and the staff from various NRC Offices, we agreed
to provide you some information concerning the fire protection
requirements for the Fort St. Vrain Station (FSV) . Specifically, the
question of compliance with the provisions of Section III.G. of Appendix
R to 10 CFR Part 50 required further clarification. Enclosure 1
provides the criteria for the Alternate Shutdown Capability for FSV and
Enclosure 2 provides the basis for these criteria. We request that you
evaluate these criteria so that we can discuss any interpretation
problems or possible alternative approaches during our fortmouriirg
meeting.
During the April 27, 1984 meeting we also made some specific comments on
the request for exemption to the various requirements of Appendix R,
which you submitted by letter dated March 2, 1984. Your sole reliance
on the previous fire protection review to the criteria of Appendix A to
BTP 9.5-1 was inappropriate given the backfit requirements of 10 CFR
50.48(b) . Our letter transmitting the fire protection rule to you
informed you of this position.
Section III.G. applies to FSV and you must reassess your plant for
conformance and modify the plant to conform or justify specific
deviations and request exemptions for those deviations. Enclosure 3
contains our guidance on the information that is needed to evaluate an
exemption application.
We agree that Section III .L. does not apply to FSV, however, Section
III .G. does apply and Enclosure 1 presents an acceptable method of
providing compliance. Section III .O. also does not apply to FSV since
the plant does not have reactor coolant pumps or a lubricating oil
system for the helium circulators. Therefore, no exemptions are needed
for Sections III.L. and III .O.
The exemption request for Section III.J. does not provide sufficient
information. Where central batteries with hardwired distribution
systems are used for emergency lighting, the licensee must analyze the
routing of all of the lighting distribution circuits to show that a fire
in the area under consideration cannot disable the emergency lighting in
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Mr. O.R. Lee -2-
any areas needed for safe shutdown following that fire including
emergency lighting for access or egress to those areas.
In summary, your March 2, 1984 requests for exemption from Sections
III .G. and III.J. require additional analysis and justification and no
exemption is required for Sections III.L. and III.O. Conformance to
Section II.G.3 should be evaluated against Enclosure 1 to this letter.
If you have any questions on this subject, please contact me at (817)
860-8127.
Sincerely,
Philip C. Wagner,
Senior Project Manager
Reactor Projects Branch 1
Enclosures: As Stated
cc: See Next Page
Public Service Company of Colorado
C. K. Millen Chairman, Board of County Comm.
Senior Vice President of Weld County, Colorado
Public Service Company Greeley, Colorado 80631
of Colorado
P. 0. Box 840 Regional Representative
Denver, Colorado 80201 Radiation Programs
Environmental Protection Agency
Donald J. Kowal , 15/148A 1860 Lincoln Street
GA Technologies, Inc. Denver, Colorado 80203
P. 0. Box 85608
San Diego, CA 92138 Don Warembourg
Nuclear Production Manager
Public Service Company of Colorado
P. 0. Box 368
J. K. Fuller, Vice President Platteville, Colorado 80651
Public Service Company
of Colorado Albert J. Hazle, Director
P. 0. Box 840 Radiation Control Division
Denver, Colorado 80201 Department of Health
4210 East 11th Avenue
Denver, Colorado 80220
G. L. Plumlee
NRC Senior Resident Inspector Kelly, Stansfield & O'Donnell
P. 0. Box 640 Public Service Company Building
Platteville, Colorado 80651 Room 900
550 15th Street
Denver, Colorado 80202
Darrell G. Eisenhut, Director
Division of Licensing
Office of Nuclear Reactor Regulation
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555
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Alternative Shutdown Capability for Ft. St. Vrain
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1. The alternative shutdown capability provided for a specific location
(area, room, or zone) shall be able to achieve and maintain sub-
critical reactivity conditions in the reactor.
During the post-fire shutdown for a fire in congested cable areas at
the G and J walls and the three room control complex, the Alternate
Cooling Method (ACM) shall ensure that plant conditions and public
health and safety consequences previously analyzed and approved for
Design Basis Accident Number 1 as defined in the FSAR Appendix D
(Revision 1) are not exceeded. To assure that a fire at the G and
J walls will not result in the loss of normal cooling systems and
the ACM, the existing manually activated sprinkler systems in these
areas shall be converted to an automatic ("pre-action" or "wet pipe")
sprinkler system that complies with the guidelines contained in
Nation Fire Protection Association (NFPA) Standard No. 13.
During the post-fire shutdown for fires in other locations of the plant,
the reactor coolant system process variables shall be maintained within
those limits predicted for a loss of normal a.c. power
2. The performance goals for the shutdown functions shall be:
a. The reactivity control function shall be capable of achieving and
maintaining a subcritical reactivity condition.
b. The pressure control function should be capable of achieving
depressurization through the helium purification system.
c. The PCRV liner cooling function should be capable of achieving and
maintaining the PCRV integrity.
d. The process monitoring function shall be capable of providing
direct readings of the process variables necessary to perform
and control the above functions.
e. The supporting functions should be capable of providing the process
cooling, lubrication, etc. necessary to permit operation of the
equipment used for safe shutdown functions.
3. The shutdown capability for specific locations may be unique for each
such area , or it may be one unique combination of systems for all such
locations. In either case, the alternate shutdown capability shall be
physically and electrically independent of the specific location and
shall accommodate post-fire conditions where offsite power is
available and where offsite power is not available for 72 hours.
Procedures shall be in effect to implement this capability.
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4. The number of operating shift personnel , exclusive of fire brigade
members , required to operate the safe shutdown equipment and systems
shall be onsite at all times the reactor is not in cold shutdown.
5. Shutdown systems installed to ensure post fire shutdown capability need
not be designed to meet seismic Category I criteria, single failure
criteria, or other design basis accident criteria , except where required
for other reasons, e.g. , because of interface with or impact on existing
safety systems, or because of adverse valve actions due to fire damage.
6. The safe shutdown equipment and systems for each location shall be
known to be isolated from associated circuits in that location so that
hot shorts, open circuits , or shorts to ground in the associated circuits
will not prevent operation of the safe shutdown equipment. . The separation
and barriers between trays and conduits containing associated circuits or
safe shutdown cables from the redundant division, or the isolation of
these associated circuits from the safe shutdown equipment, shall be such
that a postulated fire involving associated circuits will not prevent safe
shutdown.
enclosure 2
Basis for Alternative Shutdown Capability for Ft. St. Vrain
Section III .L of Appendix R to 10 CFR 50 provides the performance criteria
for Alternative and Dedicated Shutdown Capability for light water reactors.
Because of the unique design features of Ft. St. Vrain, a gas-cooled reactor,
all criteria of Section III .L are not applicable and revised acceptance
criteria have been developed. These criteria parallel the criteria for light
water reactors except for a fire in the three room control complex or in
congested cable areas at the G and J walls. For fires in these areas, the
worst case consequences include the loss of forced coolant circulation which
is Design Basis Accident Number 1 (DBA-1) as defined in the Ft. St. Vrain FSAR
Appendix D. The criteria in III .L include the requirement to have the
capability to achieve and maintain cold shutdown conditions within 72 hours
and to maintain the reactor coolant system process variables within those
limits predicted for a loss of normal a.c. power. The potential consequences
of DBA-1 for Ft. St. Vrain exceed this envelope.
The staff has considered the consequences of accepting a postulated fire
scenario that could proceed to the severity of DBA-1, which includes core
damage. The doses at the low population zone boundary for DBA-1 calculated
by the licensee and reported in Appendix D to the FSAR are: 0.37 mrem whole
body, 36 mrem thyroid, and 1.0 mrem bone. The NRC SER dated June 21, 1969
concludes that these doses are insignificant and acceptable. Based on
these consequences of DBA-1, the staff concludes that for a postulated fire
in the three room control complex or in congested cable areas at the G and
J walls, the substitution of acceptance criteria of DBA-1 in place of the
criteria in III .L relating to cold shutdown and limits or reactor coolant
system process variables is acceptable, provided that the fire protection
features in these areas are enhanced over the minimum requirements of
Section III .G.3 of Appendix R.
Enclosure 3
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CRITERIA FOR EVALUATING
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EXEMPTIONS TO SECTION III G OF APPENDIX R
OF 10 CFR PART 50
Paragraph 50.48 Fire Protection of 10 CFR Part 50 requires that all
nuclear power plants licensed prior to January 1 , 1979 satisfy the
requirements of Section III.G of Appendix R to 10 CFR Part 50.
It also requires that alternative fire protection configurations,
previously approved by an SER be reexamined for compliance with
the requirements of Section III.G. Section III.G is related to fire
protection features for ensuring that systems and associated circuits
used to achieve and maintain safe shutdown are free of fire damage.
Fire protection configurations must either meet the specific require-
ments of Section III.G or an alternative fire protection configuration
must be justified by a fire hazard analysis.
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The general criteria for accepting an alternative fire protection configur •
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ations are the following:
The alternative assures that one train of equipment necessary to -
achieve hot shutdown from either the control room or emergency control
stations is free of fire damage.
The alternative assures that fire damage to at least one train of
equipment necessary to achieve cold shutdown is limited such that• it can be repaired within a reasonable time (minor repairs with -
components stored on-site) .
Fire retardant coatings are not used as fire barriers.
Modifications required to meet Section III.G would not enhance
fire protection safety above that provided by either existing or
proposed alternatives,
Modifications required to meet Section III.G would be detrimental
to overall facility safety.
Because of the broad spectrum of potential configurations for which
exemptions. may be requested, specific criteria that account for all of
• • the parameters that are important to fird protection and consistent with
safety requirements of all plant-unique configurations have not been
developed. However, our evaluations of deviations from these require-
ments in our previous reviews and in the requests for III.G exemptions
received to date have identified some recurring configurations for which
specific criteria have been developed. a
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Section III.G.2 accepts three methods of fire protection. A passive
3-hour fire barrier should be used where possible. Where a fixed barrier
cannot be installed, an automatic suppression system in combination with
a fire barrier or a separation distance free of combustibles is used if
the configurations of systems to be protected and in-situ combustibles are
such that there is reasonable assurance that the protected systems will
survive. If this latter condition is not met, alternative shutdown capa-
bility is required and a fixed suppression system installed in the fire
•area of concern, if it contains a large concentration of cables. It is
essential to remember that these alternative requirements are not deemed
to be equivalent. However, they provide adequate protection for those
configurations in which they are accepted.
When the fire protection features of each fire area are evaluated; the
whole system of such features must be kept in perspective. The defense-
in-depth principle of fire protection programs is aimed at achieving an
adequate balance between the different features. Strengthening any one -
can compensate in some measure for weaknesses, known or unknown in others.
The adequacy of fire protection for any particular plant safety system or
area is determined by analysis of the effects of postulated fire relative
to maintaining the ability to safely shutdown the plant and minimize radio-
• active releases to the environment in the event of a fire. During these
evaluations it is necessary to consider the two-edged nature of fire
protection features recognized in General Design Criterion 3 namely, fire
protection should be provided consistent with other safety considerations.
• An evaluation must be made .for each fire area for which an exemption
is requested. During these evaluations, the staff considers the following
parameters: • ,
A. Area Description
- walls, floor, and ceiling construction
- ceiling height
• - room volume
- ventilation
- congestion
B. Safe Shutdown Capability
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- number of redundant systems in area
- whether or not system or equiment, is .required for hot shutdown
- type of equipment/cables involved
- repair time for cold shutdownaequipmnt within this area
- separation between redundant components and in-situ
concentration of combustibles •
- alternative shutdown capability
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C. Fire Hazard Analysis
- type and configuration of combustibles in area -
- quantity of combustibles
- ease of ignition and propagation
- heat release rate potential
- transient and installed combustibles
- suppression damage to equipment
- whether the area is continuously manned
- traffic through the area
- accessibility of the area .
0. Fire Protection Existing or Committed
- fire detection systems
- fire extinguishing systems - - -
- . hose station/extinguisher
• radiant heat shields .
A specific description of the fire protection features of the configuration
is required to justify the compensating features of the alternative. Low
fire loading is not a sufficient basis for granting an exemption in areas
where there are cables.
If necessary, a team of.experts, including a fire protection engineer,
will visit the site to determine the existing circumstances. This visual
inspection is also considered in the review process.
The majority of the III .G exemption• requests received to date are being
denied because they lack specificity. Licensees have not identified
the extent of the exemption requested, have not provided a technical basis
For the request and/or have not provided a specific description of the
alternative. We expect to receive requests for exemption of the following
nature:
1. Fixed fire barriers less than 3-hour rating.
2. Fire barrier without an automatic fire suppression system.
3. Less than 20 feet separation of cables with fire propagation
retardants (e.g. , coatings, blankets, covered trays) and an
automatic suppression system. •
4. For large open areas with few components to be protected and few in-situ
combustibles, no automatic suppression system with separation as in Item
3 above.
5. No fixed suppression in the control room.
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6. No fixed suppression in areas without a large concentration of cables for
which alternative shutdown capability has been provides.
Our fire research test program is conducting tests to provide information
that will be useful to determine the boundary of acceptable conditions for
fire protection configurations which do not include a fire rated barrier.
Based on deviations recently approved, specific criteria for certain
recurring configurations are as follows:
Fire Barrier Less than Three Hours
This barrier is a wall , floor, ceiling or an enclosure which separates
one fire area from another.
Exemptions may be granted for a lower rating (e.g. , one hour- or two hours)
where the fire loading is no more than 1/2 of the barrier rating. The fire
rating of the barrier shall be no less than one hour.
Exemptions may be granted for a fixed barrier with a lower fix rating
supplemented by a water curtain.
An Automatic Suppression System With Either One Hour Fire Barrier or
20-Foot Separation
This barrier is an enclosure which separates those portions of one division
which are within 20 feet of the redundant division. The suppressant may
be water or gas.
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Exemptions may be granted for configurations of redundant systems which
" have compensating features. For example:
A. Separation distances less than 20 feet may be deemed acceptable where:
1 . Fire propagation retardants (i .e. , cable coatings, covered trays,
conduits, or mineral wool blankets) assure that fire propagation •
through in-situ combustibles will not occur or will be delayed
sufficiently to ensure adequate time for detection and suppression.
2. Distance above a floor level exposure fire and below ceiling assures
that redundant systems will not be simultaneously subject to an
unacceptable temperature or heat 'flux.
B. The ommission of an automatic sup'pression system may be deemed acceptable
where:
1 . Distance above a floor level exposure fire and below ceiling assures
that redundant systems will not be simultaneously subject to an
unacceptable temperature or heat flux.
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2. The fire area is required to be manned continuously by the provisions
in the Technical Specifications.
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