ML17054A353
| ML17054A353 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 01/10/1984 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Rhode G NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 8401190224 | |
| Download: ML17054A353 (18) | |
Text
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Y'<.Ufy-V p Docket No.:
J Utullf') ST@,TES NL EAR REGULATORY COYiiVIISSION~DISTRIBUTION.
'LVASHlNGTON,O. C. 20555 Document Control g January TO, 1'984 NRC PDR L
PDR NSIC PRC LB¹2 File EHyl ton HHaughey Region I
- ELJordan, DEJA:IE
- JHTaylor, DRP:IE Bor denick, OELD ACRS (16) 50-410 Mr. Gerald K.
Rhode Senior Vice President Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202 Dear Hr. Rhode
Subject:
Safety Issues Involving Hark II Containments A former General Electric Company lead systems engineer for containment, Hr. John
- Humphrey, has identified certain safety issues involving the Hark III containments.
Since some of the issues identified by Hr. Humphrey may apply to the Hark I and Mark II containments for BWR plants, the enclosed list of issues has been trans-mitted to licensees and applicants with Hark I and Mark I'I containments.
Please provide a response to each of the concerns in the enclosure applicable to your containment within 60 days of receipt of this letter.
Response
should be submitted as changes to the FSAR.
Sincerely, If you have any questions concerning the enclosed requests for additional informa-tion, please call the Licensing Project Manager, Mary F.
Haughey, at (301) 492-7897.
o."miael signed Bpi
Enclosure:
As stated A. Schwencer, Chief Licensing Branch No.
2 Division of Licensing cc w/enclosure:
See next page DL:LB¹2+
MFHaughey:lf 1//0/84 DL:LB¹2/BC ASchwencer 1/lO /84 8401i90224 840ii0 PDR ADOCK 05000410 A
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4 ~ 4 4.5 4.6 vherc the suction is located vt11 be as much as 74'F cooler thaa thc bulk pool temperature.
Thus, thc heat-transfer through the RBR heat exchanger will bc less than expected.
The long term analysis of containmeat pressure/temperature response assumes that the, vetwell airspace is in thermal equilibri~ vith the suppression pool water at all times.
The calculated bulk pool temperature is used to determine the airspace temperature.
Tf pool thermal stratification vere considered, the surface temperature, which Is in direct contact with the airspace, vould be higher.
Therefoze the aizspace tempexature (and prcssure) would be higher A number of factors may aggravate suppression pool thermal stratification.
The chugging produced through the fizst row of horizontal vents villnot pxoduce any mixing from the suppression pool layers below the vent. row.
An uppez pool dump may contribute to additioaal suppression pool temperature stratification.
The large volume of water from the uppex pool'further submerges EHR heat exchanger effluent discharge vhich vi11 decrease edging of thc hotter, uppex'egions of the pool.
Finally, operatioa of the containment spzay eliminates the heat exchanger efflueat discharge 5et vhich contributes to nxlxing.
The initial suppression pool temperatuze Is assumed to bc 95'F while the
'aximum expected service water temperature is 90'F for all GGNS accident analyses as noted In PSAR table 6.2-50.
Zf the service vater temperature is consistently higher than expected, as occurzed at Kuosheag, thc RHR system may be required to operate nearly continuously in order to maintain suppression pool temperature at or belov the maximum perm'.ssible value ~
4.8 4
9 All analyses completed for the Hark IIIare generic in nature and do aot consider. plant specific Iateradtioas of tae RBR suppression pool suction and discharge.
Operation of the RHR system In the contaiameat spray mode vill decrease the heat traasfer coefficient through thc RHR heat cxchangers due to decreased system flov.
Thc FSAR analysis assumes a constant heat transfex'ate fxom the suppression pool even with operation of thc containment spray.
The effect on the loag term containment response aad the opexability of the spray system due to cycling the containment.
sprays on and off to maximize pool cooling aeeds to be addressed.
Also pzovide and )ustify the cx'iteria used by'he operatox for switching fxom the coatainmeat spxay mode'to pool cooling mode, and back again.
(pp.
147-148 of 5/27/82 transcript) 4.10 Justify that the curxcnt ariaagcmcnt of.the discharge aad suction points of the pool cooling system maximizes pool mixing.
(pp. 150-l55 of 5/27/82 transcx'ipt)
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5.1 5.2 D
ell to Contaiamcat B
ass Leaka e
Thc vorst case of dryvell to contaiameat bypass leakage has been established as a small brcak accident.
An intermediate brisk'ace!ident villactually produce the mast s~ificant dzyvell to containment leakage prior to Laitiatioa of coatainmcnt sprays.
Wa Undcz Technical Specification Umf.ts, bypass leakage corresponding to A/QK~ O.l ft.a coastitute acceptable operating conditions.
SmaQcr-than-IBA-sized breaks can maintain break flov into the dzyvell for long time periods, hovever, because the RPV vould bc d~eressurired over a 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> period.
Given, for example, an SBA vith A/~K~ 0.1 ~
pro)ected time period for contaiamcnt pressure to reach 15 psig is 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
In thc latter 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of the deprcssurization the containment vould presumably experience ever-increasing ovezpzessur&ation.
3.3 Leakage from the dryvcll to coataiament vi11 inczease thc temperature and prcssure in thc containment'hc operators villhave to use the coatainments spray in order to maintain contaiameat temperature and prcssure control.
Given the deczeased effectiveness of the RHR system ia accomplishing this ob]ective in the containment spray mode, the bypass leakage may increase the cyclical duty of the containment sprays.
5.4 5.5 Direct leakage from the dzyvcll to thc containmcat may dissipate hydrogen outside the region vhcre the hydrogca recombinezs take suction.
The anticipated leakage exceeds the capacity oi the dryvell purge compressors.
This could lead to pocketing of hydrogen vhich exceeds the
'oncentration limit of 4Z by volume.
Equipment may be exposed to local conditions vhich mccced the envizonmcntal qualification envelope as a result of direct Gryvcll to containment bypass leakage 5.6 N/A for Mark I and Hark II Containments
~ 5.7 5.8 Thc possibility of high temperatures ia the dryvell vithout reaching the 2 psig high pressure scram 1evcl because of bypass leakage through the dzyvelL vali should be addressed.
(pp. 168-174 of 5/27/82 transcript) 0
8.2 8.3
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~M coats'inment pzessurc equaL to ambient (0 psig) a temperatuze near maximum operating (90 F) and do aot limit the drywell pressure equal to the contsiament pzessure.
The Tech Specs operation under conditions such as a positive containmcnt pressurp (1 K,prig}, temperatures le'ss t~
maximum (60 oz 70'F) and drywi'.ll pkeksure csa be negative with respect to the containment
(-0.5 psid). Allof thes'c differences vcuid result in transient response different than the CESAR descziptions.
The dzaft GGHS technical specifications permit opczation of thc plant with containment pressure ranging between 0 aad -2 psi.g.
Xnitiatloa of containment spray at, a prcssure of -2 psig may reduce thc containment pressure by an additional 2 peig which could lead to buckliag snd failures in the contsiameat liner plate.
Xf the containmcnt is maintained at -2 psig, the top row of vents could admit blowdovn to the suppreseioa pool during an SBA without a LOCA signal being developed.
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Describe all of the possible methods bbth before snd after aa accident of creating a condition of low air'ass inside the containmcnt.
Diseuse the effects on the containment design external pressure of actuating the containment sprays.
(pp. 190-195 of-5/27/82 transcript) 9.
Final D ell Air Hase 9.1 Thc current'ESAR analysis is based upon continuous in]ection of relatively cool ECCS water into the dzyvell thxough s brokea pipe following a design basis accident.
Thc EPG's direct the operator to throttle ECCS operation to maintain reactor vessel level at about level 8.
Thus, instead of zcleasiag relatively cool ECCS vster, the brea'k villbe releasing saturated steam vhich might produce higher conts$ nmcnt prcssurisations than currently anticipated.
Therefore, thc drywell sir which vould have been drsva back into the dryvc11 villremain in the containment and higher pressures villresult ia both the
~ containment snd the dzywell.
9.2 The continuous steaming produced by throttling thc KCCS flowvill cause'ncreased direct leakage from t%c drywcll to the coatsinment.
This could zesult ia increased coatsinmcnt pressures.
9.3 Tt appears that some confusion exists as to vhethcr SBA's and stuck open SRV accideats szc treated as transients or design basis accidents.
Clarify hov they are treated snd indicate whether the initial conditions vere set st nominal or licensing values.
(pp. 202-205 of 5/27/82 trsnsczipt) 10.
D c11 Floodin Caused b
U er Pool Du 10.
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N/A for Nark I and Mark II Containments
6.'.1 6.2 RHR Permissive on Containment S ra Genexal Electric had recommende'd that the dryve11 purge compressofs "and the hydzogen recombiners be hetivtced'if the zeactox'essel'eater level drops to within one foot of the top of active fuel.
This 'requirement
@as not incorporated in the emergency procedure guidelines.
m e General Electric has recommended that an Interlock be provided to require containment spray prior to starting the recombiners because of the large quantities of h at input to the containment.
Incorrect implementation of this Interlock could result In inability to operate the x'ecombiners.
without containment spray.
6 3 The recombiners may produce "hot spots" near the zecombiner exhausts vhich might exceed the environmental qualification envelope or the containment design temperature.
6.4 Foz the containment air monitoring sysiem furnished by General Electric,.
the analyzers are not capable of measuriag hydrogen concentration at volumetric steam concentzations above 60K.
Effective measurement is precluded by condensation of steam in the equipment.
6.5 Discuss the possibility of local temperatures due to recombiner operation being higher than the temperature qualification profiles foz equipment in the region around and above the recombiners.
State what instructions, if any, are available to the operator to actuate containment sprays to keep this temperature belev designmalues.
(pp. 183-185 of 5/27/82 transcript)
Containment Pressure Res onse 7.1 7'2 The containment is assumed to be in thermal equilibzium vLth a pexfectly mixed, uniform temperature suppression pool.
As noted undez topic 4, the surface tempex'ature of the pool vigil be higher than the bulk pool temperature.
This may produce higher than expected containment tcmpezatures and pressuxes.
The computer code used by General Electric to calculate environmental qualification parameters considex's heat transfex from the suppression pool surface to the containment atmospheze.
This is not in accozdance viih the existing licensing basis for Mazk III environmental qualification.
Additionally, the bulk suppression pool temperatuxe vas used in the analysis instead of the suppression pool surface temperature.
7.3 The analysis assumes that the containment airspace Is in thermal equilibrium with the suppression pool.
In the short term this is non-conservative for Hark XII due to adiabatic compression effects and finite time required for heat and mass to be tzansferred between the pool and containment volumes.
8.
Containment Air Mass Effects 8
1 This issue is based on consideration that some Tech Specs allcnr operation at parameter values that differ from the values used in assumptions for FSAR transient analyses.
Normally analyses 'are done assuming a nominal
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Emer en Procedure Guidelines The EPGs contain a curve which specifies limitations on sup)ressMn"pool level and reactor pressure vcseel pressure.
The cuzvc present1y do'es not adequately account for upper pool dump.
At present, the operator would be required to initiate automatic depzesiurization'when the only'ction required is the opening of one additional SRV.
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Effects of Insulation Debris 18.1 18.2 19 Failures of reflective insulation in thc dzywell may lead to blockage of the gratings above thc weir annulus.
This may increase the pressure zequized in the dzywell to clear the first row of drywell vents and pertuzb the existing load definitions.
Insulation debzis may be transported through the vents in thc drywell wall into the suppression pool.
This debris could then cause blockage of the suction strainers.
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4ubmcz ence Effects on Chu in Loads 19 1
N/A for Hark I and Mark II Containments
- 19. 2 N/A for Mark I and Mark II Containments 20.
Loads on Structures Pi in and E ui ment in the D
ell Durin Reflood N/A for Mark I and Mark II Containments 21.
Containment Makeu Air Poz Backu Pur e Regulatory Guide 1.7 requires a backup purge II2 zemoval capability.
This backup, purge for Mark IIIis via the dzywcll purge line which discharges
'to the shield annulus which in turn is exhausted through the standby gas treatment system (SGTS) ~
The containment air is blown into the drywell via the drywcll puzge compressor to provide a positive purge.
The compzessors draw from the containment, however, without hydrogen'lean air makeup to the containment, no reduction in containment hydrogen concentration occuzs.
It is necessary to assuzc that the shield annulus volume contains a hydrogen lean mixture of air to be admitted to thc containment via containmcnt vacuum breakers.
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10.2 N/A for Mark I and Mark II Containments
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erational Control of D cll to Containment Differentia.-pressures 12.
0 o Hark IIIload definitions arc based upon the levels in the suppression pool and the drywell weir annulus being the same.
The GGHS technical specifications permit elevation differences between these pools.
This may effect load definition for vent clearing.
Sun ression Pool Makeu LOCA Seal In N/A for Mark I and'ark II Containments 13.
Kinet Second S ra Dela N/A for Mark I and Mark II Containments 14.
RHR backflow Throu h Containment S ra A failure in the check valve in thc LPCI line to the reactor vessel could result in direct leakage from rhe pressure vessel to thc containment atmosphere This leakage might occur as the LPCI motor operated isolation valve is closing and the motor operated isolation valve in the containment spray line is opening.
This could produce unanticipated increases in the containment spray 15.
Seconda Containment Vacuum Breaker Plenum Re onse The STRIDE plants had vacuum breakers between the containment and the secondary containment.
Qith sufficiently high flows through the vacuum breakers to containment>
vacuum could bc created in the secondary containment o 16.
Effect of Su ression Pool Level on T eraturc Measurement Some of the suppression pool temperature.
sensors arc located (by 'GE recommendation) 3" to 12" below the pool surface to provide carly warning of high pool temperature.
However, if the suppression pool is drawn down below the level of the temperature
- sensors, thc operator could be misled by erroneous readings and required safety action could be delayed.
0 Mr. Murray R.
Edelman Vice President, Nuclear. Group The Cleveland Electric Illuminating Company P.
0.
Box 5000 Cleveland, Ohio 44101 CC:
Jay Silberg, Esq.
Shaw, Pittman, Potts 8 Trowbridge 1800 M Street, N.
W.
lfashington, D.
C.
20006 Donald H. Hauser, Esq.
The Cleveland Electric Illuminating Company P. 0.
Box 5000 Cleveland, Ohio 44101 Resident Inspector's Office U. S. Nuclear Regulatory Commission Parmly at Center Road
- Perry, Ohio 44081 U. S. Nuclear Regulatory Commission Mr. James G. Keppler, Regional Administrator, Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 Oonald T. Ezzone, Esq.
Assistant Prosecuting Attorney 105 Main Street Lake'ounty Administration Center Painesville, Ohio 44077 Ms.
Sue Hiatt OCRE Interim Representative 8275 Munson Mentor, Ohio 44060 Terry J.
- Lodge, Esq.
618 N. Michigan Street Suite 105
- Toledo, Ohio 43624 John G. Cardinal, Esq.
Prosecuting Attorney Ashtabula County Courthouse Jefferson, Ohio 44047
ENCLOSURE (2)
PERRY NUCLEAR POWER PLANT UNITS 1
AND 2
REQUESTS FOR ADDITIONAL, INFORNATION CONCERNING THE EFFECTS OF HIGH ENERGY LINE BREAKS ON CONTROL SYSTENS (OPEN ITEN NO.
14) 420.03 Provide an identification of the Locations (elevations/
areas) which contain high energy piping systems and in which components -for the nonsafety related controL sys" tems are Located
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ReLate these to the adverse condi-tions discussed in your Letter dated Narch 14, 1983.
420.04 Provide a detai Led analysis for the turbine trip with" out bypass event (FSAR Section 15.2.3) in conjunction wi th a high energy Line break that causes a
Loss of feed" water heating (and subsequent increase in reactor power Level).
Without operator action, the staff is concerned 0
that this event pass event from analyzed.
could Lead to a turbine trip without by-a higher power Level than previously 420.05 If used, provi de the result's of a zone ana Lysi s and a
plant walkdown.
If zone analysis was "not used, describe the procedure by which the Locations of non-safety re-Lated controL system components affected by HELBs were determined.
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