ML20080C829
| ML20080C829 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/23/1983 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0578, RTR-NUREG-0737, RTR-NUREG-578, RTR-NUREG-737 5211-83-232, NUDOCS 8308290340 | |
| Download: ML20080C829 (14) | |
Text
.
GPU Nuclear Corporation y
gf Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057-0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
August 23, 1983 5211-83-232 Office of Nuclear Reactor Regulation Attn:
J.
F. Stolz, Chief Operating Reactor Branch No. 4 Dvision of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Sir:
Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Long Term EFW Mods (NUREG 0737 II.E.1.1)
In response to NUREG 0737 Item II.E.1.1 and as discussed in the meeting at TMI-l on July 11, 1983 with members of your Staff and those of mine, enclosed please find a description of the modifications to the Emergency Feedwater (EFW) System to be completed prior to startup f rom the Cycle 6 refueling.
The purpose of these modifications is to upgrade the EFW system to a safety grade system in order to provide increased reliability in its capability to mitigate the effects of design basis accidents when the main feedwater system is not available. These modifications will be made in accordance with the requirements of NUREG 0578 Sections 2.1.7.a and 2.1.7.b, NUREG 0737 Sections II.E.1.1 and II.E.1.2, Atomic Safety and Licensing Board (ASLB) Partial Initial Decision Section II, Subsection Q, and using the acceptance criteria of Standard Review Plan Sections 9.2.6, 10.4.9 and associated Eranch Technical position ASB 10-1 as principal guidance.
The modifications being implemented as part of this upgrade include mechanical system configuration changes, mechanical (seismic) and electrical (environ -
mental) equipment qualification upgrades, changes to the control system for EFW components and seiomic upgrade of piping sections in the Main Steam, Emergency Feedwater and Main Fcedwater Systems.
4 Sincerely, s
8308290340 930823
[
PDR ADOCK 05000289
. D. Hudill f
P PDR Director, TMI-l III IIDil:LWil:vj f I
cc:
R.' Conte, J. Van Vliet GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporstion
mEPGE!CY FEEDWATER SYSTm IING TERM SAFEIY GFADE MODIFICATIONS
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I.
Ih"IRCDICTION A.
This document describes the functional, design, quality assurance, health and safety, and licensing requirements for
-the installation and operation of modifications to the Fr.ergency Feedwater (EN) System of Unit No.1 of the 'Ihree Mile Island Nuclear Station ('IMI-1).
B.
The EN System shall remain generally as presently configured with modifications to insure the addition of emergency feedwater to both OISGs asstraing a single active failure comurrent with loss of offsite power.
In addition, the
. modified system shall be capable of providing controlled emergency feedwater flow to an intact OrSG for at least two hours without relying on alternating current (AC) power.
Conversion of direct current (EC) from the station batteries to alternating current is acceptable for this application.
1.
All automatic initiation features provided for the E m f
system shall be retained. A new automatic E m control system for controlling OrSG level independent of the Integrated Control System (ICS) shall be provided. In f.
b addition, the capability to manually control EN flow and set an automatic level setpoint from the main control room shall be provided.
I 1
2.
All the equignent required to initiate or control EN or to realign the water source to the EN pui..ps with the exception of valves EF-V4 and 5 shall be operable from the main control room.
3.
A redundant control valve shall be installed in the flow path to each OrSG in parallel with the existing control valve. A normally open block valve shall be installed downstream of each control valve to provide additional isolation capability of E N flow to an OrSG. A cavitating venturi has been provided in the E m flow path to each OrSG to limit flow.
4.
The installation and arrangement of cavitating venturis, control valves and block valves shall provide accessibility for plant maintenance, inservice inspection and operability of the cceponents.
A
.__._m...
l 5.
The installation and arrangement of electrical, instrumentation and control ccx ponents shall provide testability of equignent and maintenance of electrical separation.
6.
Fhchanical, electrical, instrumentation and control ccrrponents shall not be located in high energy line break jet zones unless they are shielded from such jets. Components shall be located such that they are
~
not subject to damage from high energy pipe whip.
II.
Fwchanical Systeras neauirements and bbdifications A.
Requiremnts 1.
Process pipire design temperature and pressure shall be consistent with the original design basis of the EEW and related service systems as identified in GAI specification SP-5544 unless system modifications call for more stringent requirefr.ents.
2.
All new piping which is part of the EEW system shall be designed, fabricated, inspected, tested and erected in acx:ordance with ANSI B 31.1 " Power Piping Code".
3.
Inspectiora required by ANSI B 31.1 shall be performed.
4.
The seismic design criteria for the piping and support system shall be in accordance with Seismic Class I design bases as defined in GAI specifications SP-5544, item 2:15, " Plant Piping for 'IMI" and the 'IMI-l FSAR.
Seismic identification syzrbol shall be S-I.
5.
Installation, erection and testire of all piping shall be in accordance with ASFE Secticn XI.
6.
Installed cleanness class shall te Class B in accordance with GPIRC Spec. 3050B-001.
7.
All new valves and the cavitatire venturis shall be designed and fabricated in accordance with ASFE Section ITI, Class 3.
.B.
bbdific.tions 1.
Add Cavitatirg Venturis in each Once Through steam Generator (OTSG) EEW Line.
(Complete) l I
a.
This modification has been implemented to limit the flow of DW to a ruptured MSG in order to ensure sufficient EEW flow to the intact MSG and to limit the mass and energy release within the reactor building for overpressure prevention. The venturis will limit the flow to the MSG in order to reduce excessive reactor coolant system (RCS) overcooling.
2.
Provide Redundant Safety Grade EIW Control and Block i
Valves a.
This is being provided to prevent a single active failure from preventing the addition of av to an MSG and to ensure the capability to isolate DW flow to a ruptured MSG.
b.
The control valves shall have sufficient range to control the EEW flow to the MSG (s) when the plant is being cooled and the MSG (s) are being depressurized and the DW flow requirement is less than that initially required.
c.
The DW system block valves shall normally be open, and in addition, the DM initiating signals shall also provide an open signal to the block valves. Each valve shall be provided with an electric motor operator and shall fail "as is" on loss of power. ne valves shall also have remote manual operation capability from the main control room.
III.
Structural Recuirements and Modifications A.
Requirements 1.
All conponents which are nart of the EEW System or which are required to act in m
- of this system shall be qualified for Safe Shutdoc c uthquake (SSE) loadings to ensure structural integrity and functional operability of active camponents during and after an earthquake.
l All existing DV system components shall be seismically qualified by analysis or by type tests if required. The qualification of new components shall be accomplished by either analysis or testing.
l 2.
We structural design of the DV system modifications j
shall be consistent with the original design basis of l
the EEW system and the related service systems as 1
i --
identified in the DTI-l FSAR and GAI specifications SP-5544 and SP-5661. Where practicable, all portions of the EEW system shall be installed indoors within seismic Class S-I aircraf t-hardened structures. All portions of the system required to perform the safety function shall be designed to Seismic Class S-I requirements.
3.
Portions of the EFW system located outdoors shall be designed to Seismic Class S-I requirements and shall be designed to withstand the effects of the design basis natural phenomena identified in the 'IMI-l FSAR Section 2.
4.
All piping and valves shall be connected and supported in such a manner that any stress due to weight, thermal effects, internal piping corditions and external environment will be within the maximum allowable stresses required by the ANSI B. 31.1 " Power Piping Code".
5.
Structural steel shall be designed in accordance with AISC-70 (including latest supplements) using ASni-A36 steel, except weld unit stresses shall be as specified in Table 9.3.2.1 of AWS Dl.1, -79 " Structural Steel Welding Code".
B.
Modifications 1.
Upgrade the EEW pumps recirculation line from recirculation control valves (EF-V-8A/B/C) to Condensate Storage Tank (CO-T1B) to Seismic Class I requirements, a.
This modification will ensure that failure of this piping due to a seismic event shall not occur and thus prevent depletion of the required CST inventory for the EFW function.
2.
Evaluate and modify the vent stacks for safety valves MS-V22A/B and atmospheric dump valves PS-V4A/B to Seismic Class I requirements.
a.
The vent stacks for safety relief valves B -V-22A/B and atrospheric dtr:p valves MS-V-4A/B are routed through the Intermediate Building floors. This modification will prevent the release of main steam to the Intermediate Building as a result of vent stack failure due to a seismic event.
Therefore, this mcdification will reduce the possibility of overpressurization in the building and protect the mergency Feedwater system components form the exposure to the hostile l
)
environment and gravity missiles.
3.
Intermediate Building Flood Protection from a Main Feedwater Line Break.
a.
This modification is being implemented to mitigate the effectc of flooding due to a poctulated rain feedwater line break in the Intermediate Building by allowing water to flow into the tendon access gallery and portions of the alligator pit which are presently isolated. By removing the upper half of the "stop walls" in the alligator pit and opening entrance "A" and "C" to the tendon access gallery, the time required for water to flood EL.
295' in the Intermediate Building will be increased from 86 seconds to approximatey 25 minutes.
IV.
Electrical Recuirements and bbdifications A.
Requirements 1.
The electric power and control system shall be designed as a Class lE system. Components of the system required to operate during a loss of all AC power (Station Blackout) shall be powered from the non-interruptable vital AC or DC buses.
2.
Each train of EFW to each orSG shall be powered from its associated power sources to facilitate safety grade initiation and control of EFW to each OTSG.
3.
Electrical equipnent shall be qualified in accordance with applicable sections of IEEE 323, IEEE 344, IEEE 382, and NURE -0588 or the Division of Operating Reactor Guidelines appended to I.E. Bulletin 79-OlB as appropriate.
B.
Modifications l.
Provide a safey grade power supply to valves CO-V-lllA/B and upgrade the cable routit.< for power supply to valves CO-V-14A/B to meet Seismic Cless I requirements.
J a.
This modification shall provide the capability to isolate a damaged Condensate Storage Tank (CST) from the EFW system by closing COV-lllA/B from the Main Control Room so that the intact CST will have sufficient water available for the EN system furction.
Similarly, the ability to close CO-V-14A/B from the Main Control Room, will allow isolation of non-EEW functions from the CST.
i These features will be used in conjunction with revised E N plant operating procedures to close CO-V-14A/BV and CO-V-lllA/B whenever there is an EEW initiation and the CST has reached the Technical Specification limit for E N inventory.
2.
Delete the existing cross connect between electrical busses that allows a control room operator to load both EEW punp motors onto a single diesel generator in order 4
to ensure electrical separation of the busses. (Ccuplete) 3.
A review shall be conducted of the emergency power bus loadings to assure that changes in bus loadings resulting from these modifications will maintain the bus loadings within acceptable limits.
V.
Instrunentation and Control Recuirements and Modifications A.
Requirements 1.
New control systems shall be installed to initate and regulate EFW flow. Control of EEW flow to each orSG shall be indeperdent of control for the other OTSG.
Each control system shall be of Class lE (safety grade) design. Electric power for the control systems shall be from safety grade uninterruptable sources.
2.
The control systems shall be designed so that no single active failure will prevent delivery of the required emergency feedwater to an OTSG. Also, the probability of a single failure causing inadvertent injection of EFW into an OTSG shall be minimized, i
3.
The control system shall be designed to enable control of emergency feedwater for at least two hours during loss of all (on-site and off-site) alternative current (AC) power sources with the exception of the battery backed 120 VAC vital sources. During the loss of all AC. _ -__ _
.~
me power condition for two hours, only the turbine driven emergency feedwater controls are required to be functional.
4.
The design of the safety grade controls shall be in accordance with applicable sections of IEEE 308, IEEE 279 and its supple.ments and IEEE 379. System level
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Iranual initiation shall not be provided as recommended by IEEE-279. Instead, the system components shall be provided with a manual starting or control capability as
~
appropriate for each component.
5.
All cable routing of electrical and instrumentation shall be checked to cocply with Appendix R of 10CFR50 (i.e., Fire Protection Evaluation).
6.
The alligator pit flood detection system shall consist of level indication located in the alligator pit.
Condenser hotwell low-low level alarm can be accmplished via the existing hotwell low-low level signals.
7.
The EFW systen shall receive automatic initiation signals for the following conditions:
a.
Ioss of both Main Feedwater Pumps, or b.
Loss of four (4) Reactor Coolant Pumps (ICP), or c.
Feedwater line break as detected by high Main Steam to Feedwater differential pressure, or d.
Iow OISG water level.
8.
The EEW system block valves shall normally be open and, in addition, the EEW initiating signals shall also provide an open signal to the block valves. A control switch shall be provided for each block valve for remote operation from the control room. Direct indication of actual valve position shall also be provided in the g
control room.
9.
The capability to manually control EIW flow from the control room shall be provided. This capability shall irclude features to allow independent control of each flow control valve and position indication from each control valve.
g 10.
The capability of selecting an automatic level control setpoint shall also be provided.
11.
The failure mode of the control valves shall be fail-closed on loss of either instrument air, electrical l
power, or control signal.
[ i l
l i
I 12.
New steam generator level instrurents external of ICS i
shall be provided for the following functions. Level is l
expressed as distance above the top of the lower tubesheet:
a.
Automatic control of EEW at 30" for the condition of at least one BCP operating and 240" for loss of all four PCP's.
b.
Initiation of EEW at a low-low OPSG water level of 18".
c.
High level alarn at 337".
l d.
Low level alarm at 23".
e.
High-high level alarm to indicate OPSG overfilling. Alarm is to occur at a water level of 380".
f.
Isolation of main feedwater (MEW) on a high-high level of 370" (which is above the ICS high level limit control point of 346").
g.
Operator selected auto level setpoint for use following a IOCA.
13.
In addition, the ICS shall utili.ze the instruments for the following purposes:
a.
OTSG level control during heat tp b.
High OPSG level limit during power operation t
c.
Low OrSG 1evel limit during power operation d.
Or5G 1evel control after the reactor trip.
14.
The modification of the OPSG level instruments shall use the top of the lower tubesheet as a reference point and use the same measurement unit (i.e., inch). These instruments shall be compensated for process pressure and environmental temperature to aid plant startup and post trip level control.
15.
Automatic EEW initiation signals for feedwater line break as detected by high main steam to feedwater differential pressure, or low OTSG water level shall be generated by using four (4) channels of level measurement and 2 out of 4 (2/4) logic for each actuation (Train A and B).
y
-g.--,c-,
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.+-, +
16.
EEW control valve modulation shall utilize two (2) channels (one for each EFW control valve) of OTSG level measurement out of a total of four (4) channels.
Howver, EEW initiation on low water level shall be dependent upon a 2 out of 4 (2/4) logic. Capability shall be provided to bypass this initiation from the main control room.
17.
Main feedwater (MEW) control shall be performed by the existing Integrated Control System (ICS). Isolated fully compensated level signals from one (1) of the four (4) channels of level measurements shall be utilized by the ICS as described above. Main feedwater isolation upon high OTSG 1evel shall be initiated by a 2 out of 4 (2/4) logic utilizing these same level signals. This shall be performed external of the ICS. Existing level instr'.unents associated with ICS shall be removed.
18.
Pain feedwater isolation shall also be initiated on a feedwater line break utilizing a 2 out of 4 (2/4) logic based upon differential pressure between main steam and feedwater system and by the Main Steam Line Rupture Detection System (MSLRDS). The MSLRDS also utilizes a 2 out of four (2/4) logic for detection of main steam pressure below 600 psig.
19.
Two (2) safety grade wide range OTSG level indications shall be provided in the control room for each OTSG.
20.
A safety grade water level indication and low-low water level alarm shall be provided in the control room for each condensate storage tank.
21.
All instrumentation independent of the ICS and control ecuipment shall be qualified for operability during a Safe Shutdown Earthquake and, when instruments are to be located in the Intermediate Buildirg, for the environmental conditions existing in the Intermediate Buildirg following a main steam line break.
B.
Modifications 1.
Deletion of the Main Steam Line Rupture Detection System (MSLRDS) Signals to the emergency feedwater control valves EF-V-30A/B.
(Conplete) f.
The deletion of the MSLRDS signals to the EFW System
[
improves the availability of the OrSG's as a heat sink i
f I
l.-
)
and improves the reliability and capability of EEW flow to the MSG (s) durirg loss of normal feedwater flow.
2.
Provide safety grade EEW initiation and main feedwater isolation on high main stea:r/feedwater differential pressure.
High main steam pressure relative to main feedwater pressure is an indication of a main feedwater line rupture. This indication along with low MSG level) anticipates failure of the secondary heat sink due to a main feedwater failure.
3.
Provide a safety grade MSG level instrumentation and signals for main feedwater (MEW) M SG high water level isolation and MSG low water level initiation of the EEW system.
The isolation of main feedwater on MSG high water level protects against MSG overfilling caused by failure of the feedwater control system within the Integrated Control System (ICS).
4.
The control system shall be of dual setpoint design with the setpoints dependent on whether or not the reactor coolant (RC) pumps are running.
On loss of all fou (4) reactor coolant (RC) pu:rps, the control system shall open and control the EEW flow control valves to maintain a higher MSG water level setpoint as required to achieve reactor natural circulation cooling within the Reactor Coolant System (ICS).
If at least one RC pump is operating, the control system shall control M SG water level to a lower setpoint sufficient for forced circulation RCS cooling.
5.
Provide a safety grade automatic control system independent of the Integrated Control System (ICS) that permits the Emergency Feedwater System to control MSG 1evel without control interaction with the main feedwater system.
6.
Upgrade the controls for the Main Steam Line Rupture Detection System to safety grade such that a single failure of the control system will not prevent isolation I
when required. The probability of a single failure causing inadvertent actuation shall be minimized.
The MSLRDS shall identify a ruptured MSG when the main steam pressure falls below 600 psig and shall then automatically isolate the main feedwater to that MSG.
8.
Provide an overspeed trip alarm in the Main Control Room for the turbine driven emergency feedwater pump (TDEWP) EF-P-1.
This alarm will provide indication of a loss of a portion of the EEW system.
9.
Provide an " alligator pit" flood detection alarm using safety grade components and a control grade main cordenser hotwell low-low level alarm in the Pain Control Room.
This modification will provide an operator with a control room alarm indicating a possible main feedwater line break.
10.
Evaluate the Emergency Feedwater and Engineered Safeguard (ES) Electrical Pcr'er, Control, and Instrumentation Cables that are presently routed through the alligator pit.
The EEW and ES electrical power, control and instrumentation cables need to be evaluated to determine their capabilty of performing their safety furrtion after a main feedwater line break incident and subsequent alligator pit flooding.
11.
A portion of the existing EEW system controls is within the ICS. This interface is being replaced with the modification as identified in previous sections. OTSG level measurements associated with the EEW system shall be provided to the ICS through suitable isolation.
VI.
Miscellaneous Criteria A.
Electrical and Control Equipment Environmental Qualification Equipment which is part of the EEW cystem or which is required to act in support of this system and which is located in the Intermediate Building, shall either be uograded to be qualified for the hostile environmental conditions resultirg from a Main Steam Line Break (MSLB) in this building or be replaced with qualified equipment or be relocated to an environmentally acceptable location which is otherwise suitable for their safety furction.
- -. = -
i B.
Paintenance Maintenarce of valves, instrumentation and controls shall te i
accanplished in accordance with manufacturcr's instructions and reconnendations. Pipe routirg and equipment location j
shall be selected to facilitate maintenance and be consistent i
with the requirements of Section I.B.
I J
C.
Surveillance and In-Service Inspection f
i Inservice inspection requirements of ASME B&PV Code Section XI for system design and inspection apply to the design of these l
modifications.
l The system shall be designed to allow functional testirg of all new equipnent during cold shutdown conditions. It shall also be designed to allow for periodic testing in accordance with the 'IMI-l 'Ibchnical Specifications, Section 4.9.
The design shall be consistent with requirements of the 'IMI-1 i
'Ibchnical Specifications limiting conditions for operation of l
the turbine cycle, Section 3.4.
D.
Interfacing Systems
}
These modifications require interfaces with the Main j
Feedwater, Main Steam, Condensate, Instrument Air and Class lE electrical systems as specifically identified in previous i
sections.
Charges to any of these systems shall not degrade the ability j
of these systems or any other plant systems to perform their j
design functions.
5 E.
Testirg Requirement j
Adequate provisions shall be made in the design of the system i
modifications to allow hydrostatic testing of the piping system, calibration of instrumentation, and functional testirn of the controls and alarms.
l
{
F.
Quality Assurance This modification is classified as Important to Safety.
i Quality Assurance requirements shall be in accordance with the "Crerational Quality Assurance Plan for 'Ihree Mile Island i
i Nuclear Station, Unit 1," with specific requirements as indicated.
4 i, _.. _ - -.
G.
Htrran Factors Human factors reviews of the man-machine interfaces shall be performed to aid in the develegnent of the system modifications. The interface points of type, location and arrangement of controls and display, system labelling, alarm / warning system logic, maintenance requirements, and procedural guidelines shall be reviewed and documented.
H.
AIAFA
'Ihe desien of this sytem shall implement AIARA concepts for both the construction activities and for the operating and maintenarce aspects of these modifications. The AIARA inpact of these modifications on other systems and personnel access shall also be considered in the design of these modifications.