ML17139B813
| ML17139B813 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 09/16/1983 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Curtis N PENNSYLVANIA POWER & LIGHT CO. |
| References | |
| NUDOCS 8309290449 | |
| Download: ML17139B813 (8) | |
Text
SEP 16 1S83 Docket No.:
60-387/388 Hr. Norman W. Curtis V'fce President Engineering and Construction - Nuclear Pennsylvania Power 8 Light Company 2 North Ninth Street Allentown, Pennsylvania 18101
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'B¹2 File EHylton RLPerch Region I
- ELJordan, DEQA: IE
- JHTaylor, DRP: IE
- Cutchin, OELD ACRS (16)
I ~
gV
Dear Hr,
Curtis;
Subject:
Susquehanna Steam Electric Station Drywell to Wetwell Vacuum Breaker Valves The NRC staff has completed fts review of the General Electric Report NEDE-22178-P that describes the methodology used to calculate the drywel'l to wetwell vacuum breaker response to certain transients fn Hark II Contafnments.
PPSL indicated that the use of the model identified fn the above report wfll predict very conservative impact velocities during pool swell transients and fnftfeted an effort to predict more realistic yet conservative impact velocities.
In a meeting held with representatfves of Shoreham, Susquehanna, Lfmerfck and Washington Nuclear Power-2 on June 7, 1983, an.:evaluation was presented on wetwell to drywell vacuum breakers under poo'I swell loading conditions that are generic to those plants.
The fnfomatfon presented durfng the meeting was submitted,by letter dated June 17, 1983 from D. H. O'onnor to R. W. Houston on behalf of Shoreham, Susquehanna and Lfmerfck.
In a letter dated June 27, 1983, PPSL indicated the adoption of the information presented fn the June 17, 1983 submittal for Susquehanna The NRC staff performed a detailed review of PP8L's submittal and finds that the analysis pres'ented fs acceptable for use fn predicting impact velocities for the vacuum breaker val,ve body and seat and fs acceptable for use fn qualifying the vacuum breakers.
The staff also finds the valve modi,fcatfon to accommodate these loads are acceptable.
The modified valves should be installed on Unit 2 prior to fuel load and for Unit 1 prior to startup following the first refueling outage.
The safety evaluation report fs enclosed.
Sincerely, Original signed by 8309290449 83091h PDR ADOCK 05000387 E
Enclosure:
As stated next a
e A. Schwencer, Chf ef Licensing Branch No. 2 Division of Lfcensfng oFFlcEII SURNAME)
DATEP DL:LB¹
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Susquehanna Mr. Norman W. Curtis Vice President Engineering and Construction Pennsylvania Power 8 Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 ccs:
Jay Silberg, Esquire
- Shaw, Pi ttman, Potts 5 Trowbridge 1800 M Street, N.
W.
Washington, D.
C.
20036 Edward M. Nagel, Esquire General Counsel and Secretary Pennsylvania Power 8 Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Mr. William E. Barberich Nuclear Licensing Group Supervisor Pennsylvania Power 8 Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Mr. G.
Rhodes Resident Inspector P. 0.
Box 52 Shickshinny, Pennsylvania 18655 Gerald R. Schultz, Esquire Susquehanna Environmental Advocates P. 0.
Box 1560 Wilkes-Barre, Pennsylvania 18703 Ms. Colleen Marsh P. 0.
Box 538A, RD 84 Mountain Top, Pennsylvania 18707 Mr. Thomas J. Halligan Correspondent The Citizens Against Nuclear Dangers P. 0.
Box 5
- Scranton, Pennsylvania 18501 Mr. J.
W. Millard Project Manager Mail Code 395 General Electric Company 175 Curtner Avenue San Jose, California 95125 Robert W. Adler, Esquire Office of Attorney General 505 Executive House P. 0.
Box 2357 Harrisburg, Pennsylvania 17120 Mr. E. B. Poser
.- Project Engineer Bechtel Power Corporation P. 0. Box 3965 San Francisco; California 94119 Dr. Judith H. Johnsrud Co-Director Environmental Coalition on Nuclear Power 433 Orlando Avenue State College, Pennsylvania 16801 Mr. Thomas M. Gerusky, Director Bureau of Radiation Protection Resources Commonwealth of Pennsylvania P. 0.
Box 2063 Harrisburg, Pennsylvania 17120
,SUPPLENENT TO THE SAFETY EVALUATION REPORT SUSQUEHANNA STEAN ELECTR I'C STATION (SSES)
The SSES containment is equipped with L
szmp e,
swing check valves to serve as vacuum breakers to equaL'h ize e pressure between the dryweLL and wetwell air space regions th t h
so a
t e reverse direction pressure across the diaphragm floor w*LL t
no excee the design d
value.
The vacuum relief valves (five assemblies) ar e mounted on selected downcomers inside the suppression pool air space region.
Fol Lowin h
'ng the onset of a Loss"of-coolant acc'd t
d d
en an urging the pool swell phase~ air f Lows from the dryweLL through the vent popes and the suppression pool into the suppression pool chamber air space resulting in a rise of the suppression pool surface and compression of the air space r egion abo t
Th ve a
as transient wetwell air space pressurization may cause the vacuum breaker valves to experience high opening and closing impact velocities.
To estimate the valve disc actuation velocities~ the Nar k II Owner's Group developed a vacuum breaker valve dynamic model (NEDE-22178-P(1))
which was submitted for review by the staff.
The Containment Systems Branch (CSB) has compLeted its review of NEDE-22178-P which describes the generic methodology used to calculate the response of the drywell-to"wetweLL vacuum breaker to certain transients in the Nark II containment (memorandum for T. Novak from T. Speis~
dated November 2~ I982.(2))
and found the approach acceptable.
(1)
"Nark II Containment DryweLL-to-QetweLL Vacuum Breaker Nodels~"
General Electric Company Repor t No.
NEDE 22178-P~
August 1982.
(2)
"Genera[ Electric To ic Report evi w "
Na k XI ray euc-ICoile cauli Facuum SreaIcer kolela 'ovember k fjI4
The applicant indicated that use of th ss model wilL Lead to predictions o+
ns o+ very conservative impact L
c ve oc~ties during pooL swell transients since the hhydrodynamic torque generated on the vaLve disc as a
con consequence of the pool sweLL d fferentiaL pressure upstream and downstream of thee valve very conservatively bounds ful'l scale test data.
Recognizing the above t he SSES applicant along with th L'
app acants for Shoreham and Limerick initiated ia e
an effort to predict more real~stzc yet conservative impact veloc't f
1es or use in the quaLi-fication of the vacuum breaker valves.
Dur ing a meeting held on June 7
1983 1n Bethesda, Naryland between the staff and the a
Li ca pp nts of Shoreham Susquehanna L
r e
nna~
smerick and MNP"2~
a presentation was made of the analy na ysss an redesign which produced a reduction in the valve va ve impact velocities during pool swe l L.
The material presented during that t'ee ing as documented in Reference 3.
Reduction of the valve impact veL t
d oca res ur ing pool swelL are attr ibuted to the use of more real' h
d ore rea 1stsc nydrodynamic torque on the valve di s ve disc.
The applicant stated that the hydrodynamic torque specified in Refe Reference 1
ss extr emely conservative.
Therefore the applicant proposed a reduction of conservat erva ism an the hydrodynamic tor que as a function of valve o
Lve opening ang le and demonstrated that~
even with the proposed reduction imp lemented in the model described (3)
"AGCO Vacuum Breaker Test Pro ra rogram Bechtel Power Corporation e
er rom D.
M. O'Conner to R.
M. Houston dated June 17~
1 983.
. ~
in Reference 1~ the predictions of d i sc impact ve locity are conservative when compared with test data.
Me have reviewed the applicant's sub tt L
mi a
s and conclude that the proposed reduction of the hydrodyna ro ynamic torque is reasonable and~ theref ore~
a cceptab Le.
Several changes were made to the val d
va ve esign~
whi ch contributed to a reduction of the impact velocities a
d t h
n o t e strentgh of the valve for withstanding these impact velocities.
The changes encompass the re uirem q
rements specified in License Condition 2.C.(16) in Susquehanna Steam Electric Station Unit 1
0 N o.
NP F-14 and i nc lude:
perat ing License Redesign of the spring cylinder L nk
(
L age sing e bar linkage instead of
- 4. bar Linkage) incorporat't f
/
io o
an actuating cy-Linder (double cylinder modification) f d
or amping; changes for a higher spring constant, thicker dome and ring f Lange use o
an internaL stop; repLacement of the shaft keys~
an pivot arm with d
higher stren th mate g
h materials; and a
change to increase the shaft bear-ing area.
The predicted paLLet impact velocities for the modified valve (using the dynami c model described in Ref erence 1, time dependent differential pressure loading across the vacuum breaker disc derived from the 4TCO test data and ad t
d t a jus e
to a peak vaLue of 5.5 PSID as recommended in NUREG"0808, and the mean hydrodynamic torque) are an opening impact velocity of Less than 1 radian/sec and a closing impact velocity of 5.8 radians/sec.
The modified a
v cuum breaker was subjected to opening and closing impact velocities higher than the predicted impact velocities.
Post-test visual inspect>on and Leakage t'est show that valve operability and integrit as a
y as a pressure boundary are maintained and~ therefore~
the wetweLL to drywell vacuum r eaker valves wi L L b
perform their function foLLowin th ing e onset of a
LOCA.
As analysis was performed for the Sh h
e ore am (opening impact
. velocity-of 12.7 r adians/sec and L
n c ossng impact velocity of 10.9 radians/sec) modified vacuum b
k d
m rea er esign to veri fy the valve's s tructural and pressure integrity.
A Linear elastic analys~s was used for the evaluation of alL valve components.
An addi tional p last 'c ana ysss was performed to L
evaluate the structural integrity of th
'd e
sps ers" for the poo L-swe L L impa ct loadings.
The "spiders" are spokes that are radially mounted on the valve disc and ar d
d are es~gned as energy absorbin members g
ers to absorb the energy associated with the disc impact Loads.
The loads and L
d b
oa corn donations were re-viewed and found to be in accordance with staff's acceptance crateraa.
The Loads were combined using the methodology in NUREG-0484. (Rev.
1)
Nethodo logy fot Combining Dynami c Responses."
The resultin str g
s resses in the, primary pressure retaining boundaries were within the ASNE Class 2 fault d
Ll bl
(
e a
owa es Servi ce Level D).
The resulting stresses in the shaft L
k an age~
an spring cylinder d
were wathan the ASNE CLass 2 emergency allowables (Service Level C) 0 The structuraL antegrzty of the spider s were verified by comparing the calculated L
p astic strain with the strain corresponding to the 4
~
allowable stresses as defined in Subparagraph F-1341.2 of Appendix F of the ASHE Boiler and Pressure Vessel Code.
Based on the analyses performed by the Shoreham applicant whi ch veri fi ed the valve structuraL a
d an pressure integrity and test results which demonstrated th L
e va ve operabi Lity and functionality~ the staff finds that the design of the modified vaccuum breaker valves for SSES s s acceptable and can accommodate the effects of pool swell impact Loadings following a design basis LOCA.
The staff concLusion is based on the analysis performed on the Shoreham valves which have the same modifications as SSES except for the additionaL actuating cylinder on the SSES valve for damping of the maximum impact velocity.
Thus~ the SSES valves wi Ll experience Lower impact velocities and corresponding Lower Loads than the Shoreham valves.