ML20028G483
| ML20028G483 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/04/1983 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| 5211-83-040, 5211-83-40, GL-81-14, NUDOCS 8302090402 | |
| Download: ML20028G483 (9) | |
Text
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O P
r GPU Nuclear Corporation Nuclear
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Middletown, Pennsylvania 17057-0191 717 944-7621 TELEX 84-2386 Writer's Direct Dial Number:
February 4, 1983 5211-83-040 Office of Nuclear Reactor Regulation i
Attn:
J. F. Stolz, Chief l
Operating Reactor Branch #4 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.
2055
Dear Sir:
1 Three Mile Island Nuclear Station, Unit 1 (TM1-1)
Operating License No. DPR-50 Docket No. 50-289 EFW Seismic Qualification On January 7,1983, GPUN staff members met with representatives of NRC and Lawrence Livermore Labs to discuss unresolved issues resulting from the TER of November 1982 and GPUN responses to the issues raised in Generic Letter 81-14. Based on those discussions enclosed please find the responses to items discussed at that meeting with the exception of item 8 which will be addressed in a nubsequent letter.
Sincerely, f-I
. Hukil V.P. - TMI-1 HDH/kik Attachment cc:
R. Jacobs l
R. G. Haynes J. Van Vliet fooI 8302090402 830204 PDR ADOCK 05000289 P
PDR GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
Item 1.
Licensee will verify and describe analyses that assures adequate water supply to achieve cold S/D.
a) time for operator action to isolate break and establish flow.
b) access to valves (flooding, etc.)
c) inoications available to operator.
d) bounoing flow (hotwell vacuum vs. break to atmosphere).
Response-GPU Nuclear has performed analyses of the water inventory needed for the emergency feedwater (EFW) system to bring the plant to the point-where cooling' can be accomplished by the decay heat removal system. These analyses were based on cooling the plant to 2500F with EFW. From this point the plant can be cooled to 2000F (cold shutdown) by the decay heat removal system.
The assumptions used in these analyses are:
1.
No operator action for twenty minutes.
2.
Decay heat generation rates were taken as 1.2 times the values for infinite operating time as given in ANS 5.1.
3.
The condensate storage tanks (CST) are initially filled to the technical specification alarm level (which results in an inventory of 155,500 gallons per tank).
4.
The plant is to be cooled at a rate greater than or equal to 500F/hr.
and less than or equal to 1000F/hr.
5.
The heat to be removed by the EFW system includes that contained in the reactor coolant and reactor coolant system materials plus the decay heat from the fuel in the reactor.
Postulated events that might effect the water inventory in the condensate storage tanks were evaluated.
These evaluations determined the rate and quantity of water loss that would result from the postulated events. The l
evaluated events include:
l 1.
Those identified in Enclosure 2 to our letter of July 7,1982 (5211-82-150).
2.
Failure of the non-seismic category I portion of the EFW pump recirculation lines.
3.
Failure of the non-seismic category I portion of the piping connecting each CST to the condenser hotwell.
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O Page 2 4.
Transfer of water from the condensate storage tanks to the condenser hotwell as a result of the condenser being at vacuum and valves in the piping between a CST and the hotwell being open (i.e., " vacuum drag" situation).
For each of the above postulated events ~1t was assumed that no operator action to mitigate the event would be accomplished before twenty' minutes had elapsed. During the 20 minute period and depending on the event, water may be lost from the CST's.
The remaining water in the CST's is sufficient to cool the plant, to the point where the decay heat removal system can be put into-service to continue cooldown to cold shutdown conditions.
The valves that might require manual operation in order to_ provide EFW to the steam generators or terminate water loss from the CST's are CO-V14A, 8; CO-Villa, B; EF-V4, 5; EF-V8A, B, C, EF-V30A, B; and CO-V176.
All of these valves (except C0476 which is at elevation 305) are located in the basement of the Intermediate Building and all can' be reached from the basement floor.
The seismic I boundary for piping between valves C0-V14 A, B and the main condenser is located outside the Intermediate Building (under the Turbine Building floor). Therefore, seismic failure of these lines within the Intermediate Building will not occur.
Access to the Reactor Building hoop tendon is made from within the " alligator" pit which is within the Intermediate Building and below the building basement floor level. This pit is open to the Intermediate Building basement via grating at the top of the pit which is at the basement floor elevation. The 1
alligator pit has a capacity of 123,570 gallons. Therefore, in the event of one or more EFW pump recirculation line failures, the pit has ample capacity to contain the leakage. Maximum leakage from simultaneous failure of all three recirculation lines is approximately 320 gpm.
j All EFW equipment is located above the basement floor level. Flood water would have to'be at a level of 13-7/8" above the floor before it made contact i
with any EFW component that could be adversely affected by the flood water.
Such flooding will not occur from recirculation line failure, due to the ability of the alligator p3t to receive and contain the water.
The following actions and indications would alert an operator to a possible loss of CST inventory:
1.
CST low and lo-lo level alarms 2.
Initiation of EFW and the procedural requirement for an operator to be dispatched to the EFW valves in the Intermediate Building basement.
3.
Condenser hotwell level alarms and possible loss of condenser vacuum should water from the CST be discharging to the hotwell.
i
.Page 3 1
Two cases have been considered for determining bounding flow loss from the
. CST's. These'are as follows:
Case A:
Line Breaks Between COV 14 A, B and the Main Condenser
- For this case, both-lines from the CST's to the condenser are assumed to be broken outside the Intermediate. Building.. This results in inventory loss but no flooding in the Intermediate Building itself.
Results:
With the two lines ruptured and no isolation of the' ruptures.for a period of twenty minutes, the combined inventory remaining in then condensate storage tanks will be 160,000 gallons.
160,000 gallons is sufficient water capacity to cool the plant.for
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eleven hours and achieve reactor coolant temperature of 2500F. At this point the decay heat removal system can be put into service.
A more-rapid cooldown, ~within the technical specification-limit of :
1000F/hr. could be achieved with less water.
Case B:
The two lines connecting the CST's to the main condenser hotwell l
- are assumed open with the hotwell operating at a vacuum of 1.6" Hg (absolute).
Results:
Assuming twenty minutes of unchecked vacuum drag -flow toL the condenser hotwell, 155,000 gallons of condensate would ' remain in.
the Condensate Storage Tanks (total). This represents an eleven hour water capacity for bringing the plant down'to 2500F using the emergency feedwater system. Again, this is adequate to bring the-plant to the point of decay heat removal system initiation.
i Item 2.
GPUN confirm that cross tie line is seismic.
i
Response
GPUN has confirmed that the cross tie line for the condensate storage tanks containing COV 111A/B is seismic Class I as indicated in Figure 1 of our response of July 7, 1982 (82-150) (See also Fig. 10.4.1 of-the TMI-1 FSAR Upoate).
Item 3.
Confirm that level instruments fail low in all cases.
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Page 4
Response
GPUN has reviewed the failure modes in a seismic event for the condensate tank level instrument (LT 43/44 Foxboro 13 DM). The level instrument is shown in the schematic below:
' cst' vent LSL H
L g
@ (1004) VBA (1006)
Power for the transmitter originates from vital-bus A (inverter feo) and the power supply and electronics are located in cabinet B in the relay room.
Scenarios:
1.
Loss of power to transmitter - level indication-in the Control Room indicates zero and the alarm circuit will actuate. Operating and emergency procedures instruct the operators to close the appropriate isolation valves.
2.
Sensing line break due to transmitter falling - The transmitter high side will be vented and the output signal will correspond to a. low level signal and alarm.
3.
Sensing line crimp due to transmitter falling - Pressure is trapped on the diaphram.
The transmitter will continue to read level. However, the operator woulo note that no drawdown is incicated and investigate the problem.
It is increalble to assume that both transmitters wou3d fail in this manner therefore, at least one transmitter is expecteo to.
be available.
4.
Flooding of CST Meter Pit - the transmitter housing is NEMA 4 anc will leak.
If the power supply is faulted by flooding the low level alarm will sound.
The Foxboro transmitter is a high quality, very relisole instrument.
This transmitter is used industrially over a wide-range of applications in severe service.
It has a high mean time between failures anc an outstanoing performance record.
In accoroance with the instrument specifications the following vibration and acceleration and orientation information is provioeo:
a.
Vibration zero shift is less than 1%.of the span for vibrations at frequencies up to 100 Hz with amplitudes up to 6 mm (0.25 in.)
peak-to-peak or for acceleration up to 20 m/s (2"g"), whichever is smaller. The transmitter is anchorea to the pit wall below grace.
The design seismic ground motion for TMI-1 is.06g (see FSAR Section 2.8.1).
Page 5
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b.
. Position Effect for a-tilt of 900 from the vertical with the capsule remaining in the vertical plant the maximum zero shift is 1.0%.
The.above specified ground motion acceleration exceed the ground motion associated with TMI-1 (See FSAR Chapter 5).
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Item 4.-
Commit to rack out breakers to COV-10A/B
Response
GPUN will disable COV-10A/B whenever the EFW system is required to be operable.
These. valves are motor operated and normally open. In the event of loss of power these valves will fail as is (open)..These valves will be i
locked with the valve opened.
Item 5.
Confirm seismic replacement of recirc flow switches ~ for EFW 8A/B during Cycle 6.
Response
The re_ circulation flow switches for EFV 8A/C will be replaced with qualified-switches during Cycle 6 refueling.
Item 6:
Address operator actions to prevent, and consequence of S/G AFW overfill. Address deadheading of EFW pumps'(including closure ofL flow control valves).
Response
The TMI-1 Restart Report Question 2 C and D Supp. 1 Part 2 addresses operator-action to mitigate steam generator overfill by the EFW system which is now" included in the Operating Procedure 1106-6 Rev. 27 dated 12/15/82 " Auxiliary Systems Operating Procedures Emergency Feed".
Pluse note that in the analysis submitted with the above Restart Report reference, flow to the OTSG during an overfilling event was taken to be -1500 gpm. However, with the deletion of the Main Steam Line Rupture Detection System (MSL RDS) (See GPUN letter 82-153) dated August 2, 1982) we have installed cavitating venturies which will limit the flow to one (1)'OTSG to less than 700 gpm. This will essentially double the response time, given in the Restart report, for an operator to take control of an overfilling event.
With the closure of both the control valves--(EFV30A/B) and the recirculation valves (EFV-8A/C) deadheading of the EFW pumps would occur and would result in damage to the EFW pump (s) in a short period of time. Simultaneous closure of the control and recirculation valves is very unlikely as discussed below in response to item 7.
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Page 6 Item 7.-
Address failure modes of E-P converters.
Response
GPUN has reviewed the failure mode'in a seismic event for the E/P converter for the EFV 30A/B valves (Bailey RP 1211)..
+ 10v open E/P EFV - 10V close 300 ir Supply A
Scenarios:
1.
Loss of Air - control valves will open.
2.
Loss of Electrical Signal - control valves will go to mid position.
l 3.
Very unlikely failures - since the E/P converter is an electronic mechanical and pneumatic device, failures may result in any valve position.
However, these failures would be' low probability ano the most likely failures would resultLin the valve being.at the mid position.
GPUN has conoucted investigations, also on failure moces of the EFW Pump Recirc Valves controls with the following results.
The controllaf recirc is via a Flow Incicating switch (FIS-78 for EFW-P1 ano FIS-77, -79 for EF-P2A, 28), ITT Barton Model No. 277.
The failure modes are:
1.
opening of high side impulse line will open valve.
2.
opening of low side impulse line will close valve.
3.
crimping of high sice impulse line will open the valve on low flow.
4.
crimping of low side impulse liner will not open the valve on low flow.
5.
loss of power, causeo by shorts to ground will close the valve (power source 125 VDC).
Item 8.
Provide reference to analyses determining AFW elec. pump capacity and required AFW flow.
Response
Later.
x Page 7 Item 9.
Provide reference to analyses showing MSIV closure _ is not required for seismic events (address bypass valves)..
Response
The TMI-l FSAR update Section 14.1.2.9, Page 14.1-21 addresses the-simultaneous rupture of the four main steam lines outside the Reactor Building. This is considered the worst case' event that could be caused by_a-
- seismic event, and bounds the failure of the steam bypass lines to the condenser. The purpose of the MSIV's is for;the hypothetical tornado missile 4
and aircraft incidents which are described in Section 10.2.1.3 of TMI-1 FSAR &-
Tech' Spec. 4.8.
Item 10.
Identify cases where double valve protection does not exist on branch lines and justify each case.
L
Response
Normal Valve Purpose Location Position Justification COV-27A/B 6" Drain CST Closed All valves indicated are COV-128A/B' 1" Drain CST normally closed during 7
COV-129A/B.
1" Drain CST Discharge system operation. -Prior to-
[
00V-130A/S 1" Vent CST Discharge startup of EFW/ Condensate COV-131A/B 1" Drain CST Discharge System the cosition of these:
COV-134A/B 1" Drain X tie
. valves are checked and re-COV-135 1" Vent CST Discharge checked. Also, single valve EFV-17 1" Drain EFP Suction isolation for normally -
EFV-18 1" Vent EFP Suction closed valves is all that is EFV-23 1" Drain EFP Suction specified by R.G. 1.29.
EFV-24 1" Drain EFP Suction EFV-25 1" Drain EFP Suction EFV-26A/B 1" Vent EFP Discharge EFV-27A/B 1" Drain EFP Discharge EFV-28A 1" Vent EFP Suction / Discharge
=EFV-29 1" Drain EFP Discharge EFV-42A/B 1" Vent EFP Suction EFV-44 1" Vent EFP Discharge EFV-43A/B 1" Drain EFP Discharge Item 11.
Provide reference to seismic status of instrument air lines for 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> supply.
Response
See Restart Report Section 2.1.1.7, FSAR Update Section 9.10.3, GPUN letters i
dated September 29, 1981, July 7, 1982, September 29, 1982 and December 20, l
1982.
l
Page 8 Item 12.
Address AFW support systems such as HVAC, service water, lube oil, etc.
Response
a.
The lube oil systems for the EFW pumps are self contained and are cooled
'by water from the EFW pump discharge.' This piping is Seismic Class I.
b.
Single failures within the heating and ventilating system and its support systems will not adversely affect operation of the EFW system due to redundancy of those systems.- Power for the HVAC is derived from Class IE power sources. Common air delivery ductwork.in the HVAC system is seismically supported.
The Nuclear Service Cooling water system which serves the HVAC units is Seismic Class I.
c.
Other than the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> instrument air supply (See Item 11 above) no other auxiliary systems than those identified in a & b above are required to operate the EFW pumps.
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