ML20132C710
| ML20132C710 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 07/26/1985 |
| From: | Mittl R Public Service Enterprise Group |
| To: | Butler W Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8507300434 | |
| Download: ML20132C710 (5) | |
Text
_
O PS G Company Pubbc Senace Electrc and Gas 80 Park Plaza, Newark, NJ 07101/ 201430-8217 MAILING ADDRESS / P.O. Box 570, Newark, NJ 07101 Robert L. Mitti General Manager Nuclear Assurance and Regulation July 26, 1985 Director of Nuclear Reactor Regulation U.S.
Nuclear Regulatorv Commission 7920 Norfolk Avenue Bethesda, MD 20814 Attention:
Mr. Walter Butler, Chief Licensing Branch 2 Division of Licensing Gentlemen:
SAFETY EVALUATION REPORT CONFIRMATORY ISSUE 1 HOPE CREEK GENERATING STATION DOCKET NO. 50-354 Enclosed, please find Public Service Electric and Gas Company's response to Safety Evaluation Report Confirmatory Issue 1.
This information will be incorporated into Amendment 12 of the Hope Creek Generating Station FSAR, as noted.
Should you have any questions in this regard, please contact us.
Very truly yours, O/
/
s
^
N, 8507300434 850726 PDR ADOCK 05000354 E
PDR C
D.
H.
Wagner USNRC Licensing Project Manager A.
R.
Blough t
USNRC Senior Resident Inspector The Energy People 954912 (3W 4 84
SER Confirmatory Issue No. 1 (SER Section 3.6.2)
Feedwater Isolation Check Valve Analysis In a letter dated August 15, 1984, the applicant provided a description of the analysis of the feedwater isolation check valves.
This analysis is to ensure that the feedwater isolation. check valves can perform their function following a postulated break of the feedwater lines outside contain-ment.
The applicant stated that the analysis will include:
(1) a thermal hydraulic analysis to determine the peak pressures upstream and downstream of the valve disk as well as the maximum disk angular speed.
(2) a sensitivity analysis to determine the break location and feedwater check valve selection that yield the
-most conservative results.
(3) an elastic or inelastic analysis of the feedwater check valves including valve internals.
The results of this analysis will be provided in November 1984.
Provided the final results meet the applicable allowable limits and design criteria of the feedwater check valves, the staff considers this approach acceptable and will report its final evaluation in a supplement to this SER.
Response
An analysis to determine the feedwater check valve dynamics and stresses following a double ended break of the feedwater line outside containment has been performed.
The results of
'the analysis indicated that the valve is qualified for the faulted condition based on the methods for analysis and design limits contained in Appendix F of the ASME B&PV Code,Section III.
The fluid dynamic analysis used the RELAP 5/ MOD 1 computer code with check valve simulation capability based on a
. generic model developed by Bechtel.
The feedwater line was assumed to be at a constant condition of 1000 psig pressure and 420*F temperature.
The break opening time was assumed to be one millisecond.
A sensitivity analysis was performed for this analysis in which the ef fect of uncertanties in input data (break opening time, valve resistance, etc.) and modeling aspects were examined.
MP 85 139 09 l-bp
As part ofLthe analysis, both the in-board and out-board valves were analyzed independently with the higher (out-board) disc angular velocity and peak line pressure at closure being used in the stress evaluation of the valve and disc.
The maximum calculated out-board check valve closure velo-
-city is 81.38 rad /sec. 'The valve closes in 110 milliseconds after break-initiation and the peak pressures upstream and 1
downstream of the valve are calculated to be 290 and 2811 psia respectively.
As part'of-the stress evaluation, the valve components of
' disc, hinge arm, valve-body, and seat ring were analyzed.
In the evaluation, two separate finite element models were used.
.The first is an axisymmetric model used to predict stresses <in-the disc and valve body.
The second is a
.two-dimensional model of'the hinge arm used to determine the maximum displacements and stresses due ' to centrifugal and impact loads.
The axisymmetric finite element model and an energy-equivalent quasi-static analysis technique were-used to analyze the disc impacting the valve seat.
In this analysis, the total energy prior to. impact is assumed to be absorbed in the. disc / valve assembly through application of-a unit static load applied to the disc.
The load was then increased incrementally until the total energy absorbed by the system was equal to the kinetic energy prior' to impact.
The kinetic energy prior to impact was conservatively estimated as 699,500 in-lbs.
In addition to the quasi-staticiloads which simulate the dynamic effects of the impact, the disc is also subjected to a differential pres-sure load due~to the fluid in the pipe.
The stress in the steel components of the disc and seat ring
. were obtained by averaging the finite element pesults across appropriate sections.
The associated stress intensities are compared to the allowable primary' stresses of 0.70 S as u
i specified in Appendix F, Table F-1322.2-1 of the ASME Code.
All stress intensities are below stress allowables except for those of the 1/16" stellite facing material.
Since the stellite stress intensity exceeds the allowable stress intensity, fracture of the stellite material ~is predicted.
This is acceptable since the stellite is'not a primary pressure retaining material.
The primary pressure boundary is formed by the steel portions of the disc and valve.
llP 85 139 09 2-bp
?
- The - hinge arm analysis considered the centrifugal force prior to impact and the impact. forces produced af ter closure of the valve.
' Applying the peak angular velocity and a
- determination"of the system frequency, the maximum centri-fugal acceleration and dynamic load factor, the deflections of the hinge arm were calculated.
It was determined that the deflections prior to impact.were insignificant and that
.t e max mum stresses in the hinge arm are below the stress h
i allowables of Appendix P' of the ASME B&PV Code.
As-stated earlier, the evaluation of the hinge arm under loads produced by closure of the valve used a quasi-static analysis technique.
The total kinetic energy of the hinge arm prior to impact is assuned to be absorbed by the hinge arm in elastic and plastic bending.
It is concluded from the analysis that the maximum stress intensities are less than the allowable of 0.70 s as specified by Appendix F, u
Table F-1322.2-1 of the ASME Code.
It is also noted that displacement calculations for this loading condition indicate that the-disc will seat properly.
The results obtained in this report are considered conservative.
In the analysis, all' kinetic energy is assumed to be absorbed as strain energy in the disc, seat ring and a portion of the valve body.
In reality, some kinetic energy of the disc will be transferred to other portions of the valve body and piping system.
Additionally, the flexibility of the piping system was not taken into account.
In addition, no increase in yield or ultimate strength was accounted for due to the high loading rates and subsequent strain rates incurred by the material.
In conclusion, for the faulted condition the 24-in 900-lb Anchor Darling feedwater swing check valve is considered in compliance with the applicable requirements of the ASME B&PV Code,Section III Nuclear Power Plant Components, Division I,-1974.
The response to FSAR Question 210.20 has been revised to reflect.the above' response.
MP 85 139 09 3-bp
QUESTION 210.20 (SECTION 3.6.2)
Provide the basis for assuring that the feedwater isolation check valves can perform their function following a postulated pipe break of the feedwater line outside containment.
RESPONSE
' b fee ater 1 e br ak out de the ontainme will e
simula d usin the RELAP5 mputer ode.
A eck v ve mode which as bee devey'oped s cifical for ca ulati s of th a natu e will use for o aining e valve dynami From this the alhyde/ulic nalysi, the p ak press ces up ream an do nstream f the valve isc as ell as t e maxi um disc-gular s eed will be ob ained.
As par of this analys's, a sen tivity nalysis ill b perfo med to etermin the be ak locat on and feedwate chec valv selecti n that telds e most c nservat e
stress esult.
The s ress nalys for t feedw. er swi check v Ive wil be perf rmed or fl id trang ent lo s indu ed by the pipe be k
eve t.
E astic and/or helasti analys s will be perform to de ermi the rimary ress i tensiti s and/or trains c itic loc ions.
or the ressur retainin boundar s such s va e bo and va ve disk the c culated Kimary s ess inte itie shall t excee Level
, Servic ' Limit (3.0 Sm).
For ther valve p ts such as sea ring, hi e, and tuator sh t,
ructura integri y will e evalua d based n strai
(
c ter determ ed by terial propertie.
The re ults of this
)
aly s will provi d in M y 1985.
___j
[' An analysis to determine the feedwater check valve dynamics and stresses following a double ended break of the feedwater line outside containment has been performed.
The RELAP 5/ MOD 1 computer code was used to predict the maximum valve disc angular velocity and the peak pressures upstream and i downstream of the valve disc following closure.
In addition, a sensitivity analysis was performed to select the feedwater check valve that yields the most conservative stress results.
An inelastic stress analysis was performed on the valve body, disc, hinge arm, and valve seat with the calculated stresses determined to be less than stress allowables.
In addition, the maximum displacement of the hinge arm before and af ter valve disc closure was determined and deemed acceptable.
Stresses were evaluated for the faulted condition based on the methods for analysis and design limits contained in Appendix F of the ASME B&PV Code,Section III.
210.20-1 Amendment 10.
l
-