ML20064E103
| ML20064E103 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 11/08/1978 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| TAC-6587, TAC-8730, NUDOCS 7811140143 | |
| Download: ML20064E103 (16) | |
Text
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NORTHERN STATES POWER COMPANY M I N N E A f*C U S. M I N N E G OTA 55401 Novec:ber 8, 19 78
,f Director of Nuclear Reactor Regulation U S Nuclear Regulatory Commission Washiraton, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PIANT Docket Nos.
0-28 License Nos. DPR-42 50-306 DPR-60 Additional Informmation Concerning The Prairie Island Fire Protection Program on Sep tembe r 13, 1978 and September 19, 1978, Northern States Power Company received from the NRC Staff, reques ts for additional informa-tio n conce rning the fire protection program at the Prairie Island Nuclear Generating Plant.
The info rmation requested was provided in draft form to the NRC inspection team at the beginning of the fire protection inspection which took place the week of October 16, 1978.
The purpose of this letter is to transmit the additional information requested by the Staff. The information provided in the attachment is subs tantially the same information made available to the NRC inspection team during their site visit.
Please contact us if you have any questions relating to the information we have provided.
L 0 Mayer, PE Manager of Nuclear Support Services LOM/DMM/deh cc: Director IE-III G Charnoff Attachment 2 2/H.4's/,U3 1
c;
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Attachment to letter dated November 8,1978 L 0 Mayer, NSP, to Director of NRR, USNRC PRAIRIE ISLAND NUCLEAR GENERATING STATION UNITS 1 & 2 Recuest for Additional Information l
8.
Provide a revised list of equipment required for achieving hot shutdown considering the following shutdown fuctions:
1.
Placing the reactor in subcritical condition and maintaining the reactor subcritical indefinitely.
2.
Bringing the reactor to hot shutdown conditions and maintaining it at hot shutdown for an extended period of time (i.e., longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />) using only normal sources of cooling water.
D 3.
Maintaining the reactor coolant system inventory indefinitely using only normal sources of makeup water.
4.
Bringing the reactor to cold shutdown conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Primary system makeup and boration capability should be considered when developing the list of equipment required for hot shutdown.
RESPONSE
Equipment required to place and maintain reactor in suberitical g dition or hot shutdown Steam Generator (SG) safety valves a.
b.
2 cooling water (CL) pumps c.
CL to component cooling (CC) heat exchanger valves:
MV-32145 MV-32146 MV-32160 MV-32161 CV-31381 CV-31411 CV-31383 CV-31384 d.
SG Ievel indication
1,
Auxiliary feedwater pump (AFWP) and associated valves e.
l Valves:
Unit 1 Unit 2 MV-32333 MV-32336 or MV-32335 or MV-32345 MV-32243 MV-32249 MV-32239 MV-32384 MV-32382 MV-32247 1
or MV-32242 or MV-32248 MV-32381 MV-32246 MV-32238 MV-32383 f.
1 CC pump per unit and associated valves.
Valves:
Unit 1 Unit 2 MV-32120 MV-32122 MV-32121 MV-32123 CV-31202 CV-31215 CV-31252 CV-31253 MV-32095 MV-32130 g.
Pressurizer level indication h.
I charging pump per unit 1.
Letdown flow Path Unit 1 Unit 2 CV-31226 CV-31230 CV-31255 CV-31279 CV-31326 CV-31347 CV-31339 CV-314 30 CV-31203 CV-31216 CV-31204 CV-31217 CV-31205 CV-31251 CV-31330 CV-31422 CV-31210 CV-31222 CV-313 33 CV-31424 MV-32199 MV-32210 MV-32166 MV-32194
4 i j
- j. I boric acid (BA) storage tank per unit 1 BA transfer pump per unit and heat tracing ET 40, 30B, 19, 23, 30A for Unit 1 ET 22, 24, 31, 43 for Unit 2 or 1 refueling water storage tank (RWST) per unit and associated valves Valves: Unit 1 Unit 2
.i j
MV-32060 MV-32062 MV-32061 MV-32063
.i k.
Pressurizer heaters 1.
Pressurizer pressure indication m.
SG power operated relief valves:
4 Unit 1 Unit 2 31089 31102 or 31084 or 31107 121,122,123,124 or 125 air compressor n.
Reactor Makeup Sources i
Charging pumps or Safety Injection (SI) pumps may be used.
Charging pumps:
l
- a. Flow from charging pump to reactor coolant system (RCS) i i
1.
seal injection flow path 2.
CV-31198
- 3. VC-7-10 b.
Suction supply 1.
Blender - requires Reactor makeup water (RM) pump l
BA. transfer pump i
Heat tracing -
ET 3C, 19, 23, 30A, 30B, 30C, t
41, 42
- 2. RWST - requires following valves Unit 1 Unit 2 MV-32060 MV-32062 MV-32061 MV 32063
S1 Pumps:
Allow RCS pressure to sag to 2000 psig by turning of f heaters and operating pressurizer power operated relief valves (POR) a.
2 CL pumps b.
CC pump c.
Valves:
Unit 1 Unit 2 MV 32079 MV-32182 or or MV-32080 MV-32183 MV-32162 MV-32190 or or MV-32163 MV-32191 MV-320 73 MV-32176 MV-320 70 MV-32173 or of MV-32068 MV-32171 d.
1 SI pump per unit
_ Additional Equipment Required to go to Cold Shutdown a.
RCS temperature indication I
b.
Accumulator isolation valves Unit 1 Unit 2 MV-32071 MV-32174 l
MV-32072 MV-32175 c.
1 RHR pump per unit Valves: Unit 1 Unit 2 MV-32164 & 32165 MV-32192 & 32193 or 32230 & 32231 or 32232 & 32233 MV-32066 MV-32169 CV-31237 CV-31240 CV-31236 or 311235 CV-311238 & 31239 l
d.
CC supply valves to RHR pumps Unit 1 Unit 2 MV-32093 or 32094 MV-32128 or 32129 b
4 9.
Discuss the role of the charging pumps in achieving hot shutdown.
RESPONSE
l The charging pumps have three functions in achieving hot shutdown.
Firs t, they provide a means of adding boric acid to the core.
i Second, they supply makeup water to the reactor coolant system (RCS). Third, they supply seal flow to the reactor coolant pumps (RCP's).
10.
Discuss the role of the component cooling water system and the cooling water system in achieving hot shutdown.
RESPONSE
I The cooling water (CL) system's role in achieving and maintaining hot shutdown consists of:
- 1) Maintains component cooling (CC) system at less than 95 F
- 2) Provides a secondary source of make up to the steam generators
- 3) Provides cooling water to:
j a) Containment coolers b) Lube-oil system on aux feedvater pumps c) Chiller units d) Diesel generators (only on loss of of fsite power) e) Air compressors The CC system's role in achieving hot shutdown consists of :
- 1) Maintain a backup thermal barrier for reactor coolant pumps
- 2) Cool letdown flow (seal water and normal letdown)
+
3)
Provide cooling for reactor coolant pump motors j
11.
Discuss any limitations for cooling the main coolant pump seals and thermal barriers that exist during hot shutdown conditions.
J
RESPONSE
i Two separate methods are provided for cooling the RCP seals and radial bearing. Either of the methods is capable of providing adequate cooling for the seals' and' bearing..These methods are:
1)
Injection System - Three charging pumps are provided on each i
unit, with one normally in service providing flow adequate to l
protect the seals and radial bearing from overheating.
a
- 2) Thermal Barrier - Component cooling, at approximately 40 gpm, is provided to the thermal barrier to protect the seals and radial bearing from overheating in the event seal injection is lost.
4
. 12.
Discuss the function of the startup neutron channel in achieving hot shutdown.
RESPONSE
The source range diannels do nothing in achieving hot shutdown.
They are not required for hot shutdown operation (Table TS.3.5-2 of the Technical Specifications).
13.
Discuss the role of the boric acid pumps and associated valves and tanks in maintaining hot shutdown conditions for an extended period of time.
RESPONSE
The boric acid pumps, valves, and tanks serve two basic functions in the maintenance of hot shtudown. First, they supply concen-trated acid to the charging pump suction, which is then injected i
into the RC system. Second, they supply concentrated acid to the l
blender, which is blended with reactor makeup water and injected i
into the RC sys tem.
This makes up for RC leakage and letdown flow that is routed to the holdup tanks.
14.
Discuss the need for pressurizer heaters in achieving hot shutdown.
RESPONSE
The pressurizer heaters and sprays are needed to maintain the reactor coolant system pressure during insurges and outsurges while reducing load to hot shutdown. Failure to provide the heaters for pressure control would result in minimal operator inconveience and no damage to the reactor coolant system while
. achieving hot shutdown.
If the heaters are los t, heat loss from the pressurizer and bypass 1
spray would result in subsequent decay in reactor coolant sys tem pressure. To maintain the reactor coolant pump net positive i
suction head, and prevent steam formation in locations other than the pressurizer, the reactor coolant system would also have to be cooled.
l 15.
Describe any manual valve operations needed to achieve hot s hu tdown,
l considering a loss of offsite power.
I
RESPONSE
The operating procedure for station blackout was made available to the dRC inspection team during their visit.
In general, motor operated valves will be powered f rom on-site power following a loss of off-site power.
- 16 Discuss the source and capacity of makeup feedwater during extended hot shutdown operations when using the atmospheric steam dump valve.
RESPONS!!
Plant Equipment :
a.
Three condensate tanks of 150,000 gallons each, b.
Water treating system consists of two trains, each with a capacity of 200,000 gallons.
c.
Each unit has two auxiliary feedwater pumps (one electric and steam) with a capacity of 200 gpm each.
one Sequence of Events:
a.
On Trip - one of two feedwater pumps stay on line b.
Steam generator level control for first hour or so af ter trip is by feedwater pump operation Af ter the feedwater heaters and associated piping have cooled, c.
an auxiliary feedwater pump is started for steam generator level control and the main feedwater pump is stopped d.
At this time in the cooldown, the water demand is approximately 75 gpm e.
Two condensate tanks of 300,000 gallons would give 66 hours7.638889e-4 days <br />0.0183 hours <br />1.09127e-4 weeks <br />2.5113e-5 months <br /> supply f.
Supply from one demin train (200,000 gals) would provide an additional 44 hours5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br /> g.
Second train would supply additional 44 hours5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br /> g3 h.
A train can be regenerated in 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, so it's conceivable the pla nt could stay in the mode of using demin trains indefinitely 1.
The ultimate backup would be use of river water through the cooling water system 17.
Provide drawings at the start of the site visit scheduled for October 16-20, which show actual separation distance of redundant cables required for safe shutdown that are located in the same fire zone.
RESPONSE
All available drawings showing cable separation were made available to tne NRC inspection team during their visit.
18.
Identify any equipment required for safe shutdown that is subject to spurious operation as a result of a fire. Particular attention is directed to valves and valve position indicators. Discuss the ef fects on safe shutdown of such spurious operation.
RESPONSE
During a fire, most of the components listed in question 8 are subject to spurious operation. As a result, no specific pieces of equipment are assumed operable from the control room, and field operation will be specified.
1
_8_
19.
Describe the function of the instrument and station air system in achieving and maintaining both hot shutdown and cold shutdown conditions. Identify any fire areas which contain components or piping of the air system and air operated valves whose position must change for shutdown. Verify that the loss of the air system will not prevent shutdown operations.
RESPONSE
The station air system has no function in shutting down the plant.
During hot shutdown, instrument air is required to support the following f unctions:
Maintain charging pump speed above minimum and control charging a.
rate b.
Control blending flow c.
Control RC letdown d.
Control SG pressure below the main steam safety valve setting Maintain CC temperature control e.
j To achieve cold shutdown, the air system is required to support the following additional functions:
RHR flow control The fire zones that have air system piping or air operated valves are 1, 31, 32, 58, 59, 60, 68, 71, 72, 73, 74, and 75 The essential shutdown functions can be performed without instrument air.
s
20.
Provide a list of remotely operated valves, with their fail positions, in safe shutdown systems.
RESPONSE
The list of valves is contained in question 8.
The motor valves (MV) fail as is.
Control valves will fail in the following manner. EU means fail open, and FC means fail closed.
VCT indicates return to volume control tank.
CV-31381 / CV-31202 FU CV-31411 / CV-31252 FC CV-31383 / CV-31215 F0 CV-31384 / CV-31253 FC CV-31226 / CV-31230 FC CV-31255 / CV-31279 FC CV-31326 / CV-31347 FC CV-31339 / CV-31430 FC CV-31203 / CV-31216 F0 CV-31204 / CV-31217 VCT CV-31205 / CV-31251 VCT CV-31330 / CV-31422 FC CV-31210 / CV-31222 FC CV-31333 / CV-31424 VCT CV-31089 / CV-31102 FC CV-31084 / CV-31107 FC 21.
Provide a failure analysis which verifies that a sit.3 e failure 1
does not impair the prLaary and backup fire suppression capabilities.
The analysis should include consideration of failures in the sup-pression system, the fire detection system or the power sources for such systems.
RESPONSE
The fire system consists of three pumps plus cross over piping.
from the cooling water system. Two pumps are at signed to normal fire duty - one electric and one diesel. The third pump is normally used for screen wash duty, but when the isolation valve between screen wash and fire header is opened, the screen wash function is automatically isolated.
The plant is circled with a 10" pipe loop with yard valves providing sectional control. A 10" plant header is provided and it has sectional valves to isolate turbine / auxiliary buildings east / west and north / south.
l Power supplies to equipment are as follows:
1.
Motor driven fire pump - 480 volt non-safeguard bus l
(incorrectly listed as a safeguards supplied load in earlier submittal) 2.
Diesel driven - dual loop battery starting. Controller and battery charger powered by DC panel 117 (a safeguard bus).
3.
Screen wash pump - 4160 volt - Bus 23 from 2M or 1R transformers.
4.
Detection system is powered from non-interruptable panel 116 which in turn is powered from safeguard bus 16.
, 22.
Describe the means provided to prevent lightning from initiating fires which could damage safety-related equipment. Describe the means provided to prevent lightning f rom damaging the fire pro-tection system.
RESPONSE
Lightning strikes to date have all been to se.ondary plant equip-ment or the plant substation. The major plant buildings were analyzed for and are protected against strikes by rods and ground-ing systems. Safeguards and fire protection equipment is located within the reinforced concrete areas of thz main plant and the sc ree nhouse.
23.
Identify any safety-related systems or their auxiliaries which are interlocked to and could be disabled by operation of a fire fighting system.
RESPONSE
Crossovers between the cooling water system and fire systems are fitted with check valves and isolation valves. Seven of the eight valves are normally closed with the eighth, a 3" line in the 4
screenhouse, open under Shif t Supervisor control. Normally the plant has operated with this valve open. Operation of the fire system would have no ef fect on the cooling water system with this one valve open.
i 6
?
. 24.
Identify the areas containing combustible liquids that are not provided wfth floor drains. Describe the drainage path and provisions for containing or diverting the combustible liquid in those aress without drains. In those areas with drains, state the capacity and location of the drain reservoirs and describe the provisions to prevent the spread of flammable liquid fires via the drain system in areas which may jeopardize safety-related equipment.
RESPONSE
Originally 'he D/G rooms had floor drains, but because of the possibility of chromates used in the diesel cooling system reaching the circulating water system and river, the lines were plugged.
Sumps are provided of approximately 3800 cu ft around each diesel.
Over flowing of the sump would allow water to run out doors to the service building sumps.
The cable spreading room and auxiliary building drains go to the alreated drain tank located in a large concrete enclosed sump below the ground level of the auxiliary building. The alreated tank has a 600 gallon capacity. Two pumps of 20 gpm each, pump from the tank to the waste holdup tank which has a capacity of 25000 gallons. If the tank over-flows, two additional 20 gpm pumps are provided to take suction from the sump and pump it to the holdup tank.
Batte ry and safeguard bus rooms do not have drains. Water would run out of the doors ending up in the turbine room sump. Water used in the control room would seep into the area below the false floor. When this area is filled, it would run out of the doors to the turbine room sump.
Level in the turbine room sump is controlled by two 250 gpm pumps which discharge to the circulating water sys tem.
From the diesel cooling water pump rooms, water can flow to the strainer room which has drains, or to a trench (9" x 9" x 48"), which drains to the screenhouse intake.
25.
Provide the results of an analysis which shows that the fire barrier penetration seals for pipe penetrations and ventilation ducts are adequate to prevent the spread of smoke fire through the barrier considering the combustible loading and possible air pressure differential.
RESPONSE
Flamemastic and thermal insulating. wool (TIW) seals are used for all penetrations of rated walls and are considered adequate.
A study of ventilation ducts through fire zone walls has been completed. In several areas where dampers were installed for one unit, they were not installed in the other. Purchase orders for engineering, purchase, and installation of dampers for deficient areas have been written. Depending on the contractor's schedule, we expect to have these dampers installed shortly after the first of the year.
We have been unable to locate qualification test results for the flamemastic;TIW seals in use at Prairie Island.
A 26.
Provide the results of an analysis that shows that curbed areas surrounding combustible liquid tanks (can hold the contained liquid)
J plub the quantity of water required for extinguishment of a fire invol-ving the combustible liquid.
RESPONSE
The only areas in the plant which have curbed restrictions around combustible liquid tanks are the oil storage room and the turbine oil reservoir tanks. These areas drain to a concrete underground vault, designed to handle the contents of the tanks and the water f rom the deluge spray system installed to protect them.
The only safeguard areas witu combustible liquid tanks are the diesel generator and diesel cooling water pump rooms. The diesel generator rooms have sumps of greater capacity then the day tanks, and the diesel cooling water pump rooms have drains.
27.
Identify all piping containing flammable. gas or combustible liquid which is routed through areas containing safety-related equipment, safety-related cables or though which personnel must pass to reach safety-related equipment for local operation. Provide an analysis to show that a fire involving the liquid or gas will not prevent safe shutdown or result in the loss of function of a safety-related sys tem.
RESPONSE
One oxygen (3/4") and one hydrogen line (l"' pass from the gas house through the east end of the turbine *uilding into the auxiliary building through fire zone 58 and part of 73. Pipes are routed over walkways in pipe runs and not over equipment or cables used for normal shutdown. The hydrogen line is fitted with a security (high flow) shut of f, the oxygen line is a low volume, low pressure supply to recombiner system that has a manual emergency shut off in a separate fire zone. The importance of isolating these pipes, due to a fire or other plant problems, is stressed in operator training classes on the gas system.
28.
Desc ribe the means provided to automatically and/or manually stop dae transfer of diesel oil f rom the bunker tanks to all diesel fuel day tanks in the event of a fire in the area housing the day tank, or through which the fuel oil transfer piping is routed.
RESPONSE
The pump selector switches are located within each diesel room, but at the opposite end of the room from the day tanks.
If entry into the room was not possible, the pumps 'can be stopped by opening breakers in a differtat fire zone, or the isolation valves from the storage tanks can be closed. Storage tanks are located.
underground outside the main plant. All piping is underground until it reaches the diesel room.
n
. 29.
In all the areas where manual fire fighting is proposed as either primary or backup means of suppression, describe the methods which would be used for heat and smoke removal using either fixed or portable air handling equipment.
If the plant HVAC systems are proposed for such service, provide design data to show that these systems are rated for the conditions (temperature and capacity) required when used for this service.
RESPONSE
The turbine building has roof exhaust fans as well as smoke hatches that are fitted with automatic releases. The probability of losing both the turbine room supply and vent fans is very small due to the very light or non-existant combustible loading in their immediate areas.
1he auxiliary building has no automatic venting hatches. The installed ventila tion equipment, although not designed for heat and smoke renoval, has the capability to f unction in that mode.
It is the opinion of vendor and plant personnel that this equipment will f unction in an emergency, and operate until there is damage to the equipment, most probably a bearing f ailure. There are dual auxiliary building normal exhaust f ans.
Loss of one fan would not affect the other resulting in a single operating fan exhausting the entire auxiliary building.
30.
Describe the m.anner in which fire and smoke are prevented from spreading fron areas via the ncrmal and emergency ventilation systems in all parts of the plant areas. Describe the location, acutation method and fire ratirg of dampers used for fire and smoke control in both air supply and return air systems. Describe the details of interlocks for ventilation system shutdown or mode change that can be utilized for fire and smoke control.
RESPONSE
It is assumed that during a fire in the auxiliary building, the ventilation system will be shut down or isolated in affected areas. During this period smoke will spread to other areas on the same level as well as upper levels where stairways 'are not enclosed.
The ventilation system can be started up and run as necessary once the fire is under control.
The safeguard rooms in the turbine building are or will be fitted with dual 1-1/2 hour rated fire dampers. Once the dampers are actuated, portable f ans will be used for smoke removal. There are no automatic interlocks provided in this design.
31.
Identify the areas where ventilation system power supplies or controls are located within the areas they serve. Provide the basis for leaving ventilation systems power and control cables within the area they serve,
RESPONSE
Ventilation system power. cables and controls are located near their associated fans in areas of the plant with trivial fire loading.
-.