ML20094H592
| ML20094H592 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/04/1992 |
| From: | Skolds J SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | George Wunder NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9203110137 | |
| Download: ML20094H592 (6) | |
Text
_
5,o 11 Cetohne Klutr4 4 Gu Cornpsny of n 6o a
"'"1"%'**"*
f;;f'"y;"l:]f "
SCEAG March 4, 1992 Document Control Desk U. S. Nuclear Regulatory Conunission Washington, DC 20555 Attention: Mr. 6, f. Wunder Gentlemen:
f
Subject:
VikGil C, SUM)tfR NUCLEAR STAT'% (VCSNS) 00CKEi NO. 60/395 OPERATING LICENSE NO. NPF-1 SAFETY EVALUA110H REPORT OH 'i41104 BLACK 0UT ANALYSIS (REG 88000i H South Caroline Electric & Gas Company has revived the Safety Evaluation Report (SER) for VCSNS Station Blackout (SBO), vepared by the NRC staff, and tne icchnical Evaluation Report (TER), preparea by its centractor Science ApplicationsInternationalCorporation(SAIC). SCELG responses to the recommendations presented in the SER are documented in Enclosure 1.
If you have any qut.stions concerning this matter, please contact Mr. tknuel W. Gutierrez at (803)345-4392.
Very truly yours, hN)
A}W C OJ (/TL.hwMC John L. Skolds MWG:JLS: led Enclosure c:
- 0. W. 01,on,lr.
General Manager R. R. Mahon NRC Resident inspector R. J. White J. B. Knotts Jr.
S. D. Ebneter RTS (REG 880002)
G. f. Wunder file (811.05, Reg. Guide 1.155) l l
NUCLEAR fXCitLENCE - A SUMK R 1RADillfMI l'
I 9203110137 920304 l
PDR ADOCK 05000395 l
p PDR
4 f nclof,ure 1 to Doccment Control liesis letter REG 880002 Page 1 of 5 VIRGli C. SOHMLR HUCtLAR SIAll0N RfSPONSL 10 NRC'S SAffly LVAtVA110N RlFORI ON VLSNS $1A110N OIACK00l ANALYSIS i
ilE.Jtu.ID01Llr.193'PLthedLSd!t 1gg;mgr1diqn:
Ihe licensee should provide.issurance of the habit ability z
in the areas where the above-cited valves are located for the duration of an SB0 event." Above-cited valves refers to air operated valves needed for coping with an SB0: Steam Generator power Operated i<elief Valves (SG PORVs) andEmergencyfeedwaterControlValves(LfWCVs),
t 1(B 9 Rei!Lqniq:
11gmJgn.eratpr Pggr_QPXf.ded ReIiCf_Yll.t1 l
Air operated SG PORVs requiring u nual operator action for decay heat removal are located in relatively large areas (east and west penatration access areas and adjacent intermediate Building).
The heat input into these areas is f rom t
insulated steam lines and piping ac:essortes attached to these lines.
Ventilation systems in these areas have been routinely removed f rom service to support maintenance activities for periods of time longer than four hours, and operator accees to these areas for routine activity has been nalntained.
i Ambient temperatures for the two relief valves in the penetration access areas have been determined by actual testing as indicated on page 7-26 of VCSNS Station Blackout Evaluation, gal Report No. 2782.
lhe testing was conducted during normal plant operation by shutting down all ventilation supply and exnaust f ans in the area and allowing the temperature to rise, lhe heat input during normal operation results in higher temperatures inan an
$80 event due to the increased number of heat sources.
The only heat source present during an $80 event is the main steam piping up to the main steam isolatior, valves.
The maximum ambient temperature recorded was 130*f in the east penetration access area, while the west penetration area reached a peak temperature of 120*f in a time period well in excess of six hours, lhe third relief valve is contained in an adjcining area of the Intermediate Building, whose volume is bounded by the test area volumes and with a section of main steam p pe providing a heat source whose surface arco is bounded by the main steam pipe surface in the. test araas. Thus, the test data of page 7-?6 is considered to demonstrate habitability for operation.
fRtD110Sy._[fta w a t tE lpAtre i V a 1 e gh The three emergency feedwater control valves requiring manual operation during an 500 event are Incated in an area in the Intermed1 ate Building with a vulume at least twice the size of the penetration access areas.
The only
--.,_.,.,r
i e
v w-
[ntiosure 1 to Document Control Desk tettor PEG 880002 Page 2 of '>
heat source in this area during an $oO event is the 4-inch main ". team supply line to the emergency feedwater pump turbine.
Therefore, reasonable assurance is provided for access to these areas to perform the required actions in response to an 500 event.
SIR kMlion P.PdddOMTELEQRm and R lt 03_ Boon!
"EtW!MLl#URO:
lhe licensee should reevaluate the temperature rise in the control room and relay room using conservative initial temperatures, corresponding to the technical specification temperature limit nr the urimum values allowed under administrative procedures, and using conservative parameters, as described in the SAIC 1[R for the heat-up calculations.
If the licensee's administrative procedures do not specify an operating temperature limit, the licensee should establish administrative procedures or revise the existing procedures to maintain the control room and relay room temperatures at or below the initial room temperatures used in the heat-up analysis, in addition, the licensee should provide a procedure which will requir? the operators to open the instrument cabinet doors within 30 minutes following an 500 event in accordance with the guidance described in huMARC 87-00."
EGLBUE2Mt C ntrg Lgene 2
The most significant heat loads are those associated with inverter and bat'.ery backed loads, as identified in Attachment 7 of gal Report No. 2/8P.
These loads were determined by reviewing existing calculations and load lists along with conservative assumptions, for which rational justification is provided. AC and DC loads were addressed, lhe heat load calculation for the control room considers the heat transfer across interfaces (through walls, including gypsum board, false ceilings, etc.).
For the adjaceret Technical Support Center and of fices, it is assumed that no heat flow is transferred through the walls. Since these areas would heat up less rapidly than the control room and any heat flow would be out of the control room, this is conservative.
Operating personnel were not included in the calculation since a staff of eight (8) members under strels condition will generate less than two (2) KW, and the total load generated from energized equipment for the -
(4) hoJr 500 duration was 14.8 KW.
The existing calculation for establishing average area ambient conditions within the control room, assuming total loss of power and subsequent loss of INAC, provides for a total continuous load of 29 KW, which envelopes the additional 2 KW for operating parsonnel.
This load (29 KW) results in a temperature increase to 120*f at the end of four (4) hours following a loss of ac power (reference Sheet 1 of Attachment 7 to gal Report 2782).
l 1
fnclosure I to Document Control Desk letter REG 880002 Pa'ge 3 of 5 lhe following initial temperatures were used in the heat ep calculation:
Control room /3*f, Outside air 10/'f, Adjacent rooms /7"i (reference VC$NS/ gal AlA Calculation Code 2.4.8.1).
Redundant air handling units are provided. Lach unit is designed to provide fJll flow tempered air and maintain the Control room ten.pcrature at irf 3 2'f, under worst beat load conditions.
The control room temperature is nnnitored and recorded once per shif t.
Review of recorded temperatures indicate that the control room is rnintained at less than 7 9F greater than 98% of the time.
fquipment and components required for coping with an $80, located within cabinets in the control room, were evaluated and justification for a
operability was provided in section 7.2.4.2 of VCSNS Station Blackout tvaluation, gal Report No. U S2. A listing of the vital components required for coping with an SB0 esent is provided in the above section and in attachment 7 to section 7 of the same report.
Reasonable assurance for operabliity was addressed based on establishing that the equipment and components were tested and exposed to temperatures equal to or greater than the 120*f calculated ambient room temperature, and were demonstrated to remoir. operable during or following the test. Main Control Board components were evaluated based on temperatures used Juring aging tests and SB0 operability limits established by Appendix f to NUMARC 87 00 Nuclear instrumentation cabincts and installed components were exposed to two 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> temperature cycles of 120*f for a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Internal temperatures for the nuclear instrumentation cabinets will not exceed the temperature experienced during extreme tests, internal temperatures for the main control board were not calculated, but the temperatures to which its Class lE, SB0 required, non-solid state or electronic components were subjected during tests significantly exceeded the 120*f SB0 temperature.
The closed door configuration of these cabinets is the seismically qualified configurctton.
Ethy RUM During our recent refueling outage, Itf6, the six Westinghouse 7.5 KVA inverters were replaced with four 10 KVA inverters.
Their efficiencies, based on actual load conditions as provided by the vendor, will be used to deterfdne new heat loads.
The relay room heat-up calculation is being revised to account for this change.
Preliminary evaluation indicd es little or no change to the heat load.
The relay room temperature was determined by c'eveloping a transient thermal model using the TSAP computer program.
The model considers room air condliions, energy addition from equipment, energy flow tc and absorption by concrete walls, f loors. ceilings, and energy f low to and f rom adjacent rooms through the wall or natural circulation through an opened door. Heat
En'elosure 1 to Document Control Desk letter RIG 080002 Pa'ge 4 of S 3
transferacrossallinterfaces(walls, floors,andceilings)isconsidered.
Wall gradients are calculated based on appropriate boundary temperature before thr: beginning of the transient.
The relay room terrperature is initially assumed to be at 71*f. The calculated worst case environaental zone temperature is 74T. Adjacent areas are initially at 77'f, and the turbine-building is held at 104*f, In order to reduce the relay room ambient temperatures, the area i
time / temperature calculation took credit fot opening doors to the Nrth and east electrical chases and the double doors to the turbine building.
Rodandant full capacity air handling units, each capable of providing f ull (104 tempered air, are designed to maintain tot relay room temperature at 7b*f 1 2*f-and the worst case heat load conditions and normally maintain the relay room temperature at near 707. 1he relay room temperature is not normally monitut ed or recordedt however, en alarm, set at 80T provides an indica *.lon of a high temperature condition in the relay room.
Although the initial-temperature used in the calculation could be more conservative, the relay room temperature used is still a conservative rapresentation of the nperating condition. A minor ductwork air path modification was made (reference MRf 20171A) to mal.itain lower re16y room temperature.
Post modification testing verifled that tht room tea.perature was reduced from 77T to 707. Additionally, $CL&G will record the temperature in the room t'or a period of time which will allo.i acquisition of temperature data te further verify that the temperature is maintained below 777. Based on existing data SCE&G has the confidence that the relay room temperature is maintained below 7/7 freater than 90% of the time.' Certain areas adjacent to the concrete walls of the relay reon could be assigned more conservative temperatures but t, ele tenperatures will not bring Significant changes to the relay room temperatm. More conservative temperatures for these areas adjacent to the relay room will be used in the ongoing re.lsion of the temperature calculation for tne relay room, which is taking into account the new inverters.
51R_ l E l190 1 2 4.2. St uaa lgthine Dni, yen AfW Pumo Bagm "Bgc& gn gtiqn:
Thelicenseeshould(1)verifyandconfirmthatallthe potential heat sources have been considered in its analysis, and (2) veriff and confirm that the surface temperature of 50*C used in the analysis for high energy.. lines is consistent with that of an SB0 esent."
S M a.3 2 i E 2 nt w The temperature calculation f or this area assumes approximately 100%
addition 6 load, above the major piping in this area, to account for miscellaneous small piping, drains, traps,'etc. A closer review of the small piping and piping accessories in this area reduces the allowed margin to about 700 Therefore, the calculated heat load is not affected by the
-inclusion of miscellaneous small piping in the area.
n
... _.. _ ~. - - - - - _ ~ -. - - -
, g
[n' closure I to Document Control Desk letter Rf,0. 80000?
Page 6 of b f
1he 60"C for the insulation surface temperature was chosen for personnel protection. A rcview of entsting pipe insulation and fluid temperatures following an SB0 event indicates that the surface temperature would be less i
than 60*C.
iherefore, actual room temperature would be less than 144*l.
4 1
MR..$CE11911. i'd TCL2'!EtDndgUng:
The Licensee should verify and coriftra that the $80 4
l equipment is or will be covered by an appropriate QA program cons htent with 1
the guidance of RG 1.155, Appendix A.
Verificction that such a program is in place should be included as part of ther documentation supporting the SB0 rule."
l t
5.{.RQ_ftiD9 Ele i
i
[quipment required to cope with an 5B0 event is under the VCSNS Quality l
Assurance Program that neets the requhtaents of Regulatory Guide 1.155,
- Appendix A.
ERLStG139 Eld "R.ggnrnenddign:
It is the M off position that an LDG reliability piogram should ba implemented which meets, as a stiinimum, the guidance of RG 1.155, i
Section 1.2.
If an EDG reitebility program currently exists, the program should be' evaluated and adjusted in accordance with RG 1.155, Section 1.7."
i Mf.!13Mp201C
' I i
VCSNS has an [DG reliability program which meets the guidance of RG 1.155 Section 1 ?.
Current VCbHS [DG reliability is greater than 95%.
l T
6
( '
i i
i l
[
l l
i vg-,w-, vv y - g y-
=wrew--,+,
- sy rw pr w v' w 'ps ' =
T-
'v-vre - v v-M + w r e
=wv fw w +- Frer ve--a vo' r=&w e - e rrwt r w-p m se = = t v e-ar'r'* *vwv '"* m tw r er w ev'e =f v +*- to v - ~*==w w er-www-*-w. a m ' ve m wre.--,we---*wrvw
- er y v e-
-