ML20082V243
| ML20082V243 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, 05000000 |
| Issue date: | 12/14/1983 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 7782N, NUDOCS 8312200035 | |
| Download: ML20082V243 (12) | |
Text
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.N Comm2nwxith Edison O ) One First Nahonal Plaza, Chicago, Ilhnois C 7 Address Reply to Post Office Box 767 Chicago, Illinois 60690 December 14, 1983 Mr. Harold R. Denton, Director Of fice of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Byron Generating Station Units 1 and 2 Braidwood Generating Station Units 1 and 2 Fire Protection NRC Docket Nos. 50-454, 50-455, 50-456, and 50-457 References (a):
August 9, 1983 letter from B.
J.
Youngblood to D. L. Farrar.
(b):
September 20, 1983, letter from T. R.
Tramm to H.
R. Denton.
(c):
November 7, 1983 summary of October 28, 1983 meeting on fire protection.
Dear Mr. Denton:
This is to provide additional information regarding fire protection st Byron and Braidwood stations.
In reference (b) we provided responses to the eighteen fire protection concerns which remained unresolved after the Byron fire protection audit in July, 1983.
As documented in reference (c), those responses have been reviewed and commented upon by the NRC.
Enclosed are revised responses to nine of the The responses to concerns 8 and 18 are still being revised and concerns.
will be provided as soon as possible.
tilso enclosed is an advance copy of the response to FSAR question 280.1 regarding inadvertent actuation of the fire suppression system in the fuel oil storage rooms.
This response will be incorporated into the FSAR at the earliest opportunity.
Please address further questions regarding this matter to this o f fice.
Ont signed original and fif teen copies of this letter and the enclosure are provided for NRC review.
8312200035 831214 PDR ADOCK 05000454 Q[m F
PDR T. R.
Tramm Nuclear Licensing Administrator q,
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7782N
Revision 1
+
BYRON - 1 RESPONSES TO FIRE PROTECTION SITE AUDIT CONCERNS Concern No. 1 In the August 16, 1982 revision to the Fire Protection Report, the applicant committed to seal fire barrier penetrations with material having a fire resistance rating comparable to the ratings of fire walls and floor /cciling assemblies.
This necessitates that sealant material be installed to an appropriate depth consistent with its UL listing.
We observed that RTV silicon sealant material was installed in the plant in thicknesses greater than the depth of the concrete floor slab.
This configuration does not appear to be consistent with the listing of the material.
We are concerned that this sealant material will not be able to withstand anticipated fire exposures.
The applicant'should verify that penetration seals featuring silicon foam, as installed in the plant, are equivalent to the structural assembly.
Response
The sealant fire test reports for the different fire stop materials used in " electrical" openings in walls, floors, or ceilings address the amount of fire stop natorial required in order to meet the required fire ratings of these fire barriers.
This information is transmitted to the installation contractor via drawings which give specific installation requirements for each openiag requiring a fire stop.
The only openings in fire rated barriers which are required to be sealed with a fire stop material in a configuration i
with a depth greater than the concrete floor, are certain electrical openings being sealed with CT Gypsum.
For these specific openings a detail has been shown on the installation drawings specifying how the required thickness is to be attained.
The type of detail used for attaining a thickness of fire stop greater than the floor or wall thickness is shown on drawing BY-E-0-5A (copy attached).
United States Gypsum Company report entitled " Concrete Floor Fire-stop Test of IEEE 383 Qualified Cable Penetrations" (copy attached) tests the fire stop material in the specific configuration shewn on the above drawing.
The fire stop sealant test reports also address the installation of plugs in installed fire stops.
For this testing an installed fire stop was drilled to make an opening and then resealed with the same fire stop material.
The instal-lation was subsequently exposed to fire tests.
The applicable test reports for the fire st.op materials used in
" electrical" openings in floors, walls, and ceilings at Byron /
Braidwood are listed below.
These test reports are currently under review to verify that the fire stops meet all applicable require-ments.
1.
CT Gypsum - Transco Test Report TR-109 2.
High Density Silicone - Transco Test Reports TR-110+TR-121 3.
Medium Density Silicone - Transco Test Report TR-lll
i Revision 1 BYRON - 1 RESPONSES TO FIRE PROTECTION SITE AUDIT CONCERNS pm Concern No. 4 In the August 16, 1982 revision to t'he Fire Protection Report, the applicant committed to comply with Section C.S.d of BTP CMEB 9.5.1 and with Section C.7.b, with the exception that an automatic fire suppression system will not be installed in " offices" in the control room complex.
We observed that the computer related storage area adjacent to the control room is not equipped with an automatic fire suppression system which is not consistent with these commit-ments.
Response
The estimates of combustible material inventories and the resulting fire loadings for the rooms in question have been revised.
As a result, the fire loadings have been substantially reduced.
The initial estimates were made over five years ago and were extremely conservative.
They reflected the uncertainty at that time regarding the expected use of these rooms.
At this time, the expected use of these rooms is much more clearly defined.
Fire Zone 2.1-1 (Record Storage Room) will be utilized as an office for two people.
Its estimated maximum combustible materials inventory is 1100 lbs.
of paper, including a transient load.
The resulting combustible loading for this room is 42,300 BTU /ft2 Fire Zone 2.1-2 (Record Storage and Toilet Room) will be used to store paper for control room recorders.
Up to 1010 lbs. of paper (a one months supply) will be stored here.
The resulting combustible loading is 2
43,900 BTU /ft.
The new combustible material inventory is consis-tent with the expected use of the rooms, while still maintaining a degree of conservatism.
These combustible inventories are consistent with those of typical office spaces.
From Table 5-9C of the NFPA Fire Protection Handbook, the average combustible inventory per square foot of floor area for 2
office spaces is 0 - 14.9 lbs/f t2 (0 - 120,000 BTU /ft ) for 60% of the floor area, 15.0 - 29.9 lbs/ft2 (120,000 - 240,000 BTU /ft ) for 2
19% of the floor area, and 30.0 - 86 lbs/ft2 (240,000 - 688,000 2
BTU /ft ) for the remaining 22% of the floor area.
The combustible loadings for these two rooms are well within the lower range listed for office space from the NFPA Fire Protection Handbook.
In fact they represent a fire hazard of light severity.
On this basis, the applicant concludes that there is no need for an automatic suppression system for either of these rooms.
The existing detection system and manual fire fighting equipment provide adequate protection for these rooms.
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The applicant further agrees that should the usage of these rooms substantially change at any time in the future, a new fire hazards analysis will be prepared and submitted to the NRC staff for approval.
The adequacy of the existing fire protection for these rooms will be re-evaluated at that time.
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Revision 1
- c.
- BYRON - 1 RESPONSES TO FIRE PROTECTION SITE AUDIT CONCERMS
' 's Concern No. 6 In the August 1G, 1983 revision to the Fire Protection Report, the applicant committed to seal fire barrier penetrations with material having a fire resistance rating comparable to the rating of fire walls and floor / ceiling assemblies.
Information was unavailable during the audit to verify that bus duct penetrations of fire rated assemblies have been sealed internally with an appropriate fire rated material.
The applicant should confirm that auch penetrations are sealed to maintain the integrity of the barrier.
In addition, we observed that fire dampers were installed in a
" ganged" configuration in several large ventilation openings in fire barriers, such as the diesel generator room exhaust vents.
This arrangement does not appear to be consistent with the listing of the damper.
The applicant should verify that the installation of the dampers in a ganged configuration will achieve a fire rating equivalent to that of the barriers in which they are installed.
Response
The bus ducts (which consist of aluminum conductors and housing with no combustibles inside) are provided with fire and smoke barriers betwaen the bus and the housing at each point where the bus duct penetrates a fire rated assembly.
For the purpose of providing further protection for safe shutdown i
equipment, all bus duct penetrations whose postulated loss could effect both trains of safe shutdown equipment will be sealed with a fire stop material with a fire rating equal to the rating of the fire barrier through which it penetrates.
We have looked at all of the bus duct penetrations and have determined that the specific bus duct penetrations which will be fire stopped are those between the Division 11 ESF Switchgear Room on Elevation 426 ' and the Non-Segregated Bus Duct Area on Elevation 439'.
The bus duct penetra-tions in the Division 12 ESF Switchgear Room will not be fire stopped since their postulated failure will not effect both trains l
of safe shutdown equipment.
Ganged fire dampers are multiple parallel fire dampers within a singular fire damper sleeve.
A,ll fire dampers at B/B are UL listed.
Revision 1 J
- e 3YRON - 1 RESPONSES TO FIRE PROTECTION SITE AUDIT CONCERNS em Concern No. 7 In the August 16, 1982 revision to the Fire Protection Report, the applicant committed to comply with NFPA Standards 13 and 15 in the design and installation of fixed water extinguishing systems.
We observed that manual discharge valves for the water deluge fire suppression systems protecting charcoal filters would be inaccessible during a fire because of their closeness to the filters and the limited access in the area.
This condition appears contrary to the commitment.
Response
The applicant takes exception to this concern.
The manual dis-charge valves in question are for the water deluge system for the charcoal filters.
The charcoal filters are enclosed by a housing constructed of 1/4-inch steel plate, and are provided with two-stage temperature alarms.
Ignition temperature of the charcoal is approximately 700*F.
The first stage set point of the temperature detector is 200*F, well below the charcoal ignition point, ensuring that the alarm would be actuated prior to development of a significant fire.
The alarm is annunciated in the main control room.
An operator would be quickly dispatched to the area to investigate the cause of the temperature alarm, and to determine if the second-stage high temperature indicator provided at the local control panel has been energized.
In all likelihood, the operator would reach the area before a fire could grow to a large enough size to render the area inaccessible.
This is especially true when the shielding offered by the steel plate filter housing is considered.
A pre-fire strategy will be developed for this area to alert the fire brigade members to the locations of the manual discharge valves.
The strategy will ensure that one of the first tasks for fire brigade members entering this area following receipt of a' first-stage temperature alarm in the charcoal filters will be to ensure that the charcoal deluge system manual discharge valves I
are accessible.
It will also cover steps to take if one or more valves are rendered inaccessible to heat from a charcoal fire.
In particular, the area around a particular valve or valves could be wetted down and cooled using manual hose stations.
In summary, the applicant believes that the high temperature alarms which annunciate in the control room will allow response to any potential fire in the charcoal filters rapidly enough that the area in which the manual discharge valve for the water deluge system is located would still be accessible.
A fire s
severe enough to render the area totally inaccessible within the short period of time during which an operator would respond to the high temperature alarm is not credible.
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Revision 1 g,
e BYRON - 1 RESPONSES TO FIRE PROTECTION SITE AUDIT CONCERNS Concern No. 10 In our Safety Evaluation Report, we stated that an oil collection system for each reactor coolant pump was required in accordance with Section C.7.a of BTP CMEB 9.5.1.
Based on observations of conditions in containment as they pertain to the fire hazard posed by the reactor coolant pumps, our conclusion regarding the need for an RCP oil collection system remains unchanged.
Response
A drip pan system which muets the guidelines of Appendix R to 10CFR50 has been designed for the Reactor Coolant Pump (RCP) motors for the Byron and Braidwood Nuclear Power Stations.
These pans are being fabricated and will be installed prior to fuel load.
Five drip pans will be installed on each pump.
These five pans will collect oil drips from all potential leakage points and route this oil to a safe collection point.
The following five pans are installed on each pump:
A drip pan inside the motor housing below the lower motor bearing.
A drip pan under the bottom of the oil cooler.
A drip pan around the oil cooler under the upper flange.
A drip pan which encloses the oil lift pump.
A drip pan under the oil level alarm and sight gauge.
The pans are designed such that all external piping connections are above the pans.
A piping system collects all the oil drips and seepage and routes the oil to closed containers in the contain-ment which are sized to collect the amount of oil expected to be collected between outages.
In the event of a major leak, an overflow line from the containers will transfer the oil directly into the containment oil collection vault.
In the unlikely event the vault is overfilled, the oil would back up into the containment floor drain sump.
Under no conditions would the oil drain into an area which is not closed.
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.*v Rnvision 1 BYRON - 1 RESPONSES TO FIRE PROTECTION SITE AUDIT CONCERNS Concern No. 11 In the August 16, 1982 revision to the Fire Protection Report, the applicant committed to comply with NFPA Standard No. 20 regarding the installation of fire pumps.
We observed that an unlisted controller has been installed for the electric motor driven fire pump which is not consistent with that commitment.
Response
Due to the location of the motor driven fire pump (in the River Screen House), it was necessary to drive the pump with a 4000V motor.
Since Underwriters Laboratories (UL) labels are not supplied on motors or starters rated over 600V, it was not possible to meet the specific commitment in NFPA Standard No. 20 requiring that the controller for the electric motor driven fire pump must be UL listed.
However, in an effort to meet the intent of the NFPA standard, it was required that the 4kV -
motor and controller should utilize components with approved documented reliability equal to UL or Factory Mutual labled controllers.
All fire pumps and controllers are subjected to a final field acceptance test.
Based on these requirements, M&M Protection Consultants have determined that the fire pumps and controllers are acceptable.
NFPA 20, Chapter 7, Section 7-6 " Controllers Rated in Excess of 600 Volts" lists the specific requirements for electric motor driven fire pumps rated in excess of 600 Volts.
The Byron /
Braidwood design is in compliance with this section with the following exceptions:
7-6.5
" Low-Voltage Control Circuit" - This subsection specifies that the low voltage control circuit t
i be supplied from a stepdown control circuit transformer whereas the B/B design has the control l
circuit powered from the 125VDC system.
The B/B design is more reliable sinoa the source is safety-related.
7-6.6
" Alarm and Signal Devices on Controller" - This subsection specifies that a pilot light be provided on the controller to indicate that power is avail-able.
This feature is not included in the B/B design since there are alarms for pump running, failure to start, and loss of power which are located in the main control room.
Revision 1
BYRON - 1 RESPONSES TO FIRE PROTECTION SITE AUDIT CONCERNS Concern No. 12 In the August 16, 1982 revision to the Fire Protection Report, the applicant committed to comply with Section C.5.d(l), " Control of Combustibles" of BTP CMEB 9.5.1.
In the diesel generator rooms and at the Auxiliary Fuel Pump Room, we observed that curbs were not provided at doorways into these areas and therefore, a potential existed for a diesel fuel fire to propagate through the doorway into adjoining areas.
The applicant should provide curbs at these doorways to be consistent with their commitment.
Response
The applicant's position has been in the past, and continues to be, that curbs are not required for either the diesel generator rooms or for the diesel-driven auxiliary feedwater pump room.
The existing Byron /Braidwood design provides adequate protection against a postulated spill of diesel fuel.
A description of the existing design and the justification for the applicants position are documented in Attachment A to the September 20, 1983 letter from Mr. T. R. Tramm (CECO) to Mr. H. R. Denton (NRC).
Neverthe-less, in order to avoid any delay in the Byron unit 1 fuel load date, the applicant will install curbs in these rooms.
The diesel generator rooms will be provided with 3/4 inch high threshholds underneath the rolling steel door and the personnel access door.
Due to the large floor area of these rooms, the 3/4 inch height of the threshholds will be sufficient to contain any postulated i
oil spill.
The diesel-driven auxiliary feedwater pump room will have a curb installed of sufficient height to contain any postulated oil spill in this room.
These modifications will be completed prior to fuel load.
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BYRON - 1 RESPONSES TO FIRE PROTECTION SITE AUDIT CONCERNS Concern No. 14 To comply with Section C.S.g(l) of BTP CMEB 9.5.1, fixed self-contained lighting consisting of flourescent or sealed beam units with individual 8-hour minimum battery power napplies should be provided in all plant areas that need to be manned for safe shut-down and all routes to these areas.
We observed that the Essential Safety Features Switchgear Room has not been provided with 8-hour battery powered emergency lighting as required.
All other areas of the plant that are accessed for safe shutdown have been provided with emergency lighting off of individual battery units or the station batteries.
The use of station batteries represents a deviation from our fire protection guide-lines.
To be considered acceptable, the applicant would have to demonstrate that a fire in an area containing emergency lighting off of the station batteries would not affect battery powered emergency lighting in all other plant areas.
Response
The applicant agrees that the ESF switchgear rooms should have been provided with 8-hour battery powered emergency lighting.
A design change to add such lighting to both ESF switchgear rooms has been initiated.
In addition, the applicanc agrees to provide 8-hour battery powered emergency lights along access routes from the control room to other areas or rooms which may require access for safe shutdown.
These other areas include the Remote Shutdown Control Room on elevation 383'-0" (access via stairwell near 23/L), the fire hazards panel in the electrical penetration area on elevation 426'-0" (access via stairwell near r
23/L, the elevation 426'-0" auxiliary building general area, and the fuel handling building), the ESF switchgear rooms on elevation 426'-0" (access via the turbine building main floor and the stairwell near 7/L), and the Auxilairy Electric Equipment Room adjacent to the Control Room.
The lighting provided for these areas and the access routes identified above will be individual 8-hour battery powered emergency lights.
The new lighting will be installed prior to fuel load.
Revision 1
,;. 3 BYRON - 1 RESPONSES TO FIRE PROTECTION SITE AUDIT CONCERNS Concern No. 17 We observed that, because of the absence of an automatic fire suppression system and the lack of a fire wall between redundant divisions, both RHR pumps and related cabling are vulnerable to a fire located in the. containment spray pump area.
To satisfy the guidelines in Section C.5.b of BTP CMEB 9.5.1, the unprotec-ted openings in the wall separating the Division 11 RHR pump room from the containment spray pump area should be protected to prevent the passage of smoke and heat.
Response
It is the applicant's position that the residual heat removal pump rooms are already adequately separated, and that upgrading one or both of the intervening pump cubicle walls to a rated fire barrier is not warranted.
The reasons for this are as follows:
The division 11 RHR pump cubicle is separated from the division 12 RHR pump cubicle by over 70 feet.
The intervening rooms contain the division 11 and 12 containment spray pumps.
The combustible loading 2in these rooms is conservatively estimated to be 10,300 BTU /ft (division 11 CS pump room) and 36,200 ETU/ft' (division 12 CS pump room).
The majority of this material consists of cable insulation and jacket materials.
Because these are controlled access areas, no transient combustibles are assumed.
All of these rooms are p'rovided with ionization type fire detection.
These combustible loadings are quite small, and the materials constitute a low fire hazard.
Any fire which could occur in these CS pump rooms would not be of sufficient severity to propagated to the adjoining RHR pump rooms.
The RHR pump cubicle walls, and door, while not fire rated, are of substantial construction, and could withstand a fire of the severity which might occur here without structural failure.
In addition, the RHR pumps are not required for normal plant operation nor to maintain the plant in hot standby.
They are only used to bring the plant to cold shutdown.
Thus, as allowed by Appendix R, credit can be taken for making repairs in the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> interval prior to the time when the pumps are required.
- Thus, any cables which may have suffered fire damage due to a fire in the CS pump cubicles coula be replaced or repaired during this time.
The Byron pre-fire plans will be revised to alert the fire brigade to the potential repairs which may be required in these rooms.
The specific repair procedure which would be used in this instance has not yet been completed.
- However, it will be completed, approved and implemented prior to fuel load.
The Auxiliary Systems Branch has accepted this commitment in Section 9.5.1.4 of Supplement No. 3 of The Byron SER.
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For these reasons, the applicant believes that upgrading the PHR pump cubicle walls to fire rated barriers is not required.
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3 B/B-FSAR
,CUESTION 280.1 "In the Fire Protection Report you state that the primary fire suppression system for the fuel oil storage tan'<
rooms is an automatic protein foam extinguishing system.
You further state that inadvertent operation of this foam water system would not affect the equipment -(fuel oil transfer pumps) in the room, since spillage would be rapidly removed by the sump pumps.
We disagree with this statement.
The fire protection system, the controls, and the sump syatem are non-safety related systems which are not qualified for seismic events or harsh environ-ments, even though they are seismically supported.
Show that spurious action of this fire protection system will not affect the availability and operability of the fuel oil transfer pumps."
RESPONSE
In the unlikely event of an inadvertent actuation of the foam suppression system in a diesel oil storage tank room, the function of one train of diesel oil transfer pumps could
,be lost.
To insure that a single failure would not result in a loss of both diesel operations, a cross connection between the two day tanks is being provided.
This cross connection includes a normally closed manual valve to. main-tain system separation under normal conditions.
In the event it becomes necessary to supply a diesel from the opposite 4
train day tank, approximately one hour will be available to open the valve.
The cross-connecting piping is sized to allow adgquate flow for full power diesel operation.
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