ML20032A272
| ML20032A272 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 10/16/1981 |
| From: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20032A271 | List: |
| References | |
| NUDOCS 8110290227 | |
| Download: ML20032A272 (4) | |
Text
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October 16, 1981 t, 7 s c h,,%,%/8g7 c
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N,k qd Mr. Harold R. Denton V.
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Office of Nuclear Beactor Regulation U. S. Nuclear Regulatory Ctenission Washington, D. C.
20555
Subject:
Virgil C. Sumer Nuclear Station Docket No. 50/395 Alternate Shutdown Systm
Dear Mr. Dentcn:
In response te a tele @one conversation with NRC staff members cn September 2,1981, South Carolina Electric and Gas Cmpany provides the following inform;. tion.
Safe shutdown can te achieved utilizing the Cbntrol Rom Evacuation Panel (CREP) for pstulated fires in the control rom, relay room, and the two cable spreading rooms (control cxxnplex). As documented in the SGSG Fire Pici.cction Evaluation, fires outside the control cmplex do not require operation frm CREP.
In the event of a fire requising utilization of the CREP concurrent with total loss of offsite pwer, the turbine driven emergency feedwater pump, the corresponding flow control valves a.d n
the steam code safety valves are the initial equipnent required for maintainance of a Hot Standby conditicn for at least two hours. 'Ihe turbine driven energency feedwater pznp and diesels start autcmatically cn a loss of offsite pwer. An alternate control power sugly is not needed since the steam valve for the turbine fails open on loss of power and/or air. 'Ihe code safety valves are autmatic mechanim i devices. 'Ihe flow control valves (IFV 3536-EF, IW 3546-EF, and IW 3556-EF) can be controlled fran the CREP if control air is available; without air, one man is required to control these l
valves locally. Steam generator level indicators with circuits and pwer supplies independent of the control bui3 ding are available at I
the CREP (LI 477B, LI 487B, LI 4978). PMin ccanunication is l
available between the CREP and the valve operating station.
Calculations have shown that reactor coolant systen makeup is not needed for more than two hours after a reactor trip and loss of l
offsite pwer. However, operating procedure EOP-8 is arranged to ensure the capability for makeup can be established within a snort I
time after the start of the incident. Establishing the capability 5
j for makeup requires the following:
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Iccal manual tripping of the switchgear breaker for the i
offsite source to coe of the two main Class lE buses and l
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- 10. Harold R. Denton October 16, 1981 Page 2 local manual closure of the associated diesel generator breaker.
2.
Starting a service water pmp using controls at the CREP (these controls have an alternate source of control that is independent of the control cmplex.)
3.
Startig the associated chilled water ptrnp with local manual operation of the switchgear treaker.
4.
Starting a chiller frm local control switch in the chiller control package and subsequent local manual operation of the switchgear breaker.
5.
Starting c. charging pump by local manual operation of the switchgear breaker.
6.
Provide an initial source of borated weter to the charging pump by opening valve XVI 8104-CS and starting boric acid transfer pmp XPP 13B-G.
Both the valve and pump can be conttolled frm the CREP (these controls have a source of control power independent of the control emplex). Also, boric acid tank level indication (LI-161 and LI-163 which have pwer supplies independent of the control cxxnplex) are available at the CREP.
7.
Pressurizer level indication (LI-459B Miich has power supply independent of the control emplex) is available at the CREP.
@e various HVAC systes listed in Attachment I to the Fire Protection Evaluation are needed to ensure the long term reliable operation of the associated process system equipnent. Recent preliminary evaluations have shown that HVAC systes are not required for sme time after the start of the incident.
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@ e design method for depressurization in the event that shutdown utilizing the CREP is required is the use of the Eressurizer power operated relief valves (PORV's). Valves PCV 445 A and PCV 444 B can both be operated frm the CREP, have electrical pwer sources independent of the control cmplex and have nitrogen accumulators which makes their operation independent of the instrument air system.
'Ibe staff questioned whether we rely on making any repairs to equipnent as a result of fire rather than provide separation or an alternate system. A fire in the area of the A train RHR pump cooling unit could pssibly damage cables for both trains of the cooling unit. A tauru.ary cable is provided therefore to repair the damaged B train cables. Shutdown of the plant under this scenario is frcm the control rom.
W e staff requested that this repair be identified on the cold shutdown equipnent table (Refer to May 14, 1981 letter to NRC).
Since the purpse of this table, was to identify equignent and i
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6 Mr. Harold R. Dentm October 16, 1981 Page 3 circuits maary for shutdown given a fire anywhere in the plant, we prefer not to emplicate the table further with notes such as this. 1his prticular repair is identified in the Fire Fi:ct.ection Evaluation.
The staff requested that doceentation of a I:reviously pedvs.:a test (en the implementation of EOP-6) be Irovided. The tast that was performed was a walk through test and was not groperly documented, i
It was confirmed that the actions could be -lished in a reasonable time. A more detailed test will be clanducted in the upcming hot functional test.
Testing will be conducted to denonstrate that the plant can be maintained in Hot Staadby, and cooled down apgraximately 50 F frm Hot Standby. This testing will.h==nt the time to energize the Control Ro m Evacuation Panel and to implement plant operating 4
'n procedure E0P-8, " Control Ibm Evacuation"..1his testing will also demonstrate the capability to initiate Residual Heat Removal frm outside the Control Room by implenenting plant operating suci: Jure GDP-8, " Plant Shutdown from Hot Standby to Cold Shutdown with Control Rom Inaccessible". Please find attached these two operating Irocedures (EOP-8 and GOP-8) that will be implemented to accmplish this testing. E0P-8 is in draft form and will be apgroved in approximately one week.
There will be a separate Startup gvcidure to h= ant the results.
Regarding the staff position that an 1 % ndent source range monitor be provided at the CREP, it is the Ensition of SCE&G that this is unnac====_ry becanaa of the increase in shutdown margin before cooldown. An inadvertant boren dilution, considerireJ a loss of offsite power, is an unlikely W ant because the available sources of water are borated. The reactor makeM2p pumps would not supply non-borated water since there is a fail close valve in the flow path.
The only water available for make-up to the Beactor Coolant System (RCS) is borated either fr m the Boric Acid Tanks, as described in the svei:dare or fra the Refueling Water Storage Tank (RWST). To w Mate for the system leakage by maintaining pressurizer level, make-up as described results in a significant increase in shutdown margin. Additional make-up required to m,u Mate RCS volume contraction during cooldown using the boric acid stoiage will insure that the reactor is maintained in a subcritical conditicn.
We trust that the information provided above will resolve your renaining concerns on our alternate shutdown capability and with the information Irovided in our letters dated July 16,1981, and
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Mr. Harold R. Denton Oce b e 16, 1981 Page 4 August 21, 1981, should allow you to close SER open itans 1.6.10.
If you have any questions, please let us know.
Very truly yours,
/
4
'A T. C. Nichols, Jr.
NEC:TCN:lkb Attachment cc:
V. C. Suraner G. H. Fischer T. C. Nichols, Jr.
H. N. Cyrus
-J. C. Ruoff D. A. Nauman W. A. Williams, Jr.
R. B. Clary O. S. Bradham A. R. Koon M. N. Browne B. A. Bursey J. L. Skolds J. B. Knotts, Jr.
H. E. Yoccm J. B. Cookinham i
NPCF File l
l l
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