ML19309B577
| ML19309B577 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/04/1980 |
| From: | Wilson R METROPOLITAN EDISON CO. |
| To: | Jay Collins NRC - TMI-2 OPERATIONS/SUPPORT TASK FORCE |
| References | |
| TLL-078, TLL-78, NUDOCS 8004040318 | |
| Download: ML19309B577 (6) | |
Text
~
l 10G K CT 4
!REGUXOR'l DDCKET i:lLE CO?Y Metropolitan Edison Company m.
I[*J f {')
Post Office Box 480 Middletown, Pennsylvania 17057 P
717 944 4041 Writer's Direct Dial Number March 4, 1980 TLL 078 TMI Support Attn:
J. T. Collins, Deputy Director U. 6. Nuclear Regulatory Commission c/o Three' Mile Island Nuclear Station Middletown, Pa.
17057
Dear Sir:
Three Mile Island Nuclear Station, Unit II (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 BOP Diesel Generators The present mode of decay heat removal at.TMI-II is by steaming OTSG "A" to the main condenser.
Heat is transferred from the core to the steam generator by natural circulation in the "A" primary loop.
This cooling mode requires the operation of circulating water pumps and condensate pumps.
These pump drives represent large electrical loads.
The original plant design provided that the power supply to these electrical loads was not vital.
Therefore, it was not necessary to provide a back-up source of emergency-electrical power.
After the accident a back-up power source to these busses was supplied by BOP diesel-generators and a 115 kV intertie for the unlikely event of loss-of-off-site power.
Because of the capability to provide power to the 115 kV intertie with combustion turbines, this power source has been classified as an acceptable back-up source of power for necessary equipment for the removal of decay heat from the reactor in the present mode of core cooling.
Since sufficient electrical power, in the normal mode and the emergency mode, is available to power the necessary core cooling equipment, removal of the BOP diesel-generators, as an additional back-up source of power, is justified.
Attachment A provides further details concerning this justification.
It is anticipated that this submittal provide adequate information to enable your evaluation of this proposal.
The schedule for removal of these diesel-generators from service is early April, 1980, dependent on the completion of the work necessary to implement the 115 ki' interties and/or alternate modes of reactor heat removal.
ce =ly, sh R. F. Wil on Director, TMI-II C~
RFW:LJL:hh 800.4040 W cc:
R. Vollmer
[
R. Fitzpatrick
0 Attachment A TLL 078 BOP DIESEL - GENERATOR REMOVAL INTRODUCTION Following the accident at TMI-II, secondary plant equipment was utilized to provide the necessary core decay heat removal.
To ensure a reliable
' source of power to this equipment in the event of loss of offsite power, udditional 2500 kw diesel generators and 10MVA transformer was leased and installed as shown in Figure 1.
The 10MVA transformer was connected to the 115 kv transmission grid which was separated from the normal 230 kv grid supplying the station auxiliary transformers.
Since the 115 kv grid could be backed up by combustion turbines this source was considered equiva' ent to an onsite power supply.
Table 1, Vital BOP Electrical Loads for TMI-II, is provided to tabulate those components, supplied from the non-vital busses, that are important for reactor decay heat removal.
The current mode of core cooling (steaming OTSG "A" to the condenser on natural circulation), in addition to the backup cooling mode (long term cooling using forced circulation of the secondary side of OTSG "B") require large secondary plant, non-vital electrical loads.
Among these loads are the condensate pumps, the circulating water pumps and the new high pressure pump, LTB-P-1.
Upon the improbable loss-of-off-site power to the non-vital busses, either the BOP diesel-generators or the installed 10MVA transformer can adequately supply these necessary electrical loads.
Because the capacity of the 10MVA transformer is adequate to supply the necessary secondary plant electrical loads and has been classified an adequate back-up power supply to the station auxiliary transformers, the BOP diesel-generators can be disconnected.
Moreover, the source of power for the 10MVA transformer has been determined to be an acceptable source of backup power for the core cooling components such as condensate pumps, circulating water pumps, etc.
Specifically, in a memorandum from V. Stello to R. C. Arnold, dated April 16, 1979, it is stated, "We find the design criteria for the use of the 13.8 kv construction power source as a back-up for the circulating water pumps to be acceptable."
Furthermore, NUREG 0557, Evaluation of Long-Term Post-Accident Core Cooling of Three Mile Island Unit II, Appendix B, states, "We find the addition of the 13.2 kv transmission line as a backup power source to be acceptable given the operational needs and time restraints present at Three Mile Island Unit II."
'S BOP DIESEL GENERATOR REMOVAL Attachment A (page 2)
TLL 078 TECHNICAL APPROACH The technical approach to be taken to implement this proposed change will be to supply the non-vital busses from the J0MVA transformer that is supplied from the 115 kv, combustion-turbine powered bus.
(Significantly, the combustion turbines have a " black start" capability.)
To implement this technical approach it is necessary to install new connections as shown on Figure 2.,
Because the capacity of the 10MVA transformer is adequate to provide power to the long-term cooling components required of OTSG "A" cooling or OTSG "B" cooling, the requirement to retain the BOP diesel-generators no longer exists.
l 1
l 4
From 115 KV Grid From 230 KV Grid
$r it if Leased W W 10 MVA MT XMF 2A Aux w y 28 Aux gy I,,
XMF XMF frn on gy gy To 6900V Buses bNC U NC NO o
Bus 2-5 Bus 2-6 dN0 J
NC N0 n NC u
c1 N0 r2 Bus 2-3 Bus 2-4 b NC bNC n N0 o NO Leased Leased DG A DG B B0P 2500 KW 2500 KW (Gray)
(White)
A F
1P O
n N0 a N0 m NC Bus 2-lE BUS 2-2E
- 'C NC N0 N0 y
()
n Safety Related DE-X-1A DE-X-1B DG DG 3000 KW 3000 KW
1 1
From 230 KV Grid
' From 1,,5 KV Grid e v WW Leased 10 m m MVA XMF W y 2B Aux wy 2A Aux
}6 XMF XMF an rn gw gn To 6900V Buses
[3 fiU NC a NC a
Bus 2-5 Bus 2-6 Ia N0 1
New onnectio n c,
NC a NC y N0 N0 r1 c3 Bus 2-3 l
Bus 2-4 N0 N0 O No c.New Connection D0P d
F O
O N0 El NO O NC Bus 2-1E Bus 2-2E NC NC NO Y
a NO n
Safety i
Related DE-X-1A DE-X-1B DG DG 3000 KW 3000 KW
=
VITAL BOP ELECTRICAL LOADS FOR THI-II OPERATION REQ'D IJDAD SIZE / SUPPLY COOLING HODE 13.8 KV CRAY Wil OTSG OTSG B FUNCTION SYSTDI COMPONENT BUS 1.I N E D.C.
D.C.
A II. P.
REMARKS t
i DECAY llEAT RDIOVAL Cir2. Wlter System Cire. Water Pump CW-P-1A 2-5 2250 tiP X
Une one of two pumps Cire. Water Pump Cu-P-lC 2-5 2250 llP X
Cire. Water PP Valves CW-V-1A, CW-V-lC 2-51 1 IIP X
i h
Condensate System Condensate Pumps CO-P-1A 2-3 900 IIP X
Use one of two only j
CO-P-lC 2-3 900 IIP 900 llP X
in OTSG A Cooling Schedule y
I long T;rm OTSC B New H.P. Pump B 2-4 700 Ilr X
i CooliIg Sec. S::rvices Closed Sec. Closed Cooling Cooling Water System PP SC-P-1B 2-41B 200 llP X
Use two of three i
Sec. Closed Cooling PP SC-P-lC 2-41B 200 IIP X
Sec. Closed Cooling PP SC-P-1A 2-31B 200 IIP X
Condine:r Vacuum System VA-P-18 2-31A DO IIP X
Two of Three Requited 2-41A Concurrently. VA-P-1B VA-P-lc 2-31 A 200 IIP X
may be swung to either VA-P-1A 2-31A 200 itP X
base.
Temporrry Auxiliary Bollar 2-41C 15 KW X
TABcE 1 TLL 078 0
9