ML17195A010
| ML17195A010 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, 05000000 |
| Issue date: | 11/04/1983 |
| From: | Wright R Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17195A009 | List: |
| References | |
| NUDOCS 8311080233 | |
| Download: ML17195A010 (5) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION DRESDEN, UNITS 2 AND 3 DOCKET NUMBERS 50-237 AND 50-249 QUAD CITIES STATION, UNITS 1 AND 2 DOCKET NUMBERS 50-254 AND 50-265 DEMONSTRATION OF CONTAINMENT PURGE AND VENT VALVE OPERABILITY (B-24)
- 1. 0 Regui rement Demonstration of operability of the containment purge and vent valves, parti-cularly the ability of these valves to close during a design basis accident, is necessary to assure containment isolation. This demonstration of opera-bility is required by BTP CS~ 6-4 and SRP 3.10 for containment *purge and vent valves which are not sealed closed during operational conditions 1, 2, 3, and
- 4.
2.0 Description of Purge and Vent Valves The valves identified as the containment isolation valves in the purge and vent system are as follows:
Unit No.
2 2
2 2
3 3
3 3
Unit No.
1 1
1 1
Dresden Station Units 2 and 3 Size Valve Number
{Inches}
Use A0-2-1601-21 18 Not given A0-2-1601-22 18 Not given A0-2-1601-23 18 Not given A0-2-1601-24 18 Not given A0-3-1601-21 18 Not given A0-3-1601-22 18 Not given A0-3-1601-23 18 Not given A0-3-1601-24 18 Not given Quad Cities Station Units 1 and 2 Size Valve Number
{Inches}
Use A0-1-1601-21 18 Not given A0-1-1601-22 18 Not given A0-1-1601-23 18 Not given A0-1-1601-24 18 Not given Location Outside containment Outside containment Outside containment Outside containment Outside containment Outside containment Outside containment
.Outside containment Location Outside containment Outside containment Outside containment Outside containment 2
A0-2-1601-21 18 Not given Outside containment 2
A0-2-1601-22 18 Not given Outside containment 2
A0-2-1601-23
--*18 Not given Outst.de containment 2
A0-2-1~01-24 18 Not given Outs~de containment
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The subject_ valves are butterfly type Model 2FII manufactured by H. Pratt Com-pany.
T~e Quad Cities valves are equipped with Tomkins-Johnson (part number AU-10-31) actuators and the Dresden valves with Miller (part number VPS-2502) actuators.
The valves are to be operated from their full open {0° =full open) position.
3.0 Demonstration of Operability 3.1 Commonwealth Edison (CE) has provided purge and vent valve operability demonstration information for Uresden, Units 2 and 3 and Quad Cities, Units 1 and 2 in the following submittals:
A.
July 6, 1981 letter, T. J. Rausch (CE) to G. C. Lainas (NRC).
B.
February 27, 1981 letter, R. F. Janecek (CE) to G. C. Lainas (NRC).
- c.
August 22, 1980 *letter R. F. Janecek (CE) -to G. C. Lainas (NRC).
3.2 Commonwealth Edison's (CE) dynamic torque (To) predictions. for the sub-ject 18-inch valves stem from dynamic torque coefficients (Cr) developed from a 6-inch (1/3 scale) model valve bench test program as documented in Appendix A of Reference C.
The inlet piping configuration used in the test program was configured to establish uniform approach flow to the test valve.
Flow tests were conducted with the valve. disc set at fixed opening angle rang-ing from 8° to 78° (0° = full open) in 10° increments.
Valve inlet pressures of 20 psia, 38 psia and 63 psia were established for each disc setting. Tor-que data measured off the 6-inch valve shaft was scaled to predict torques developed in the 18-inch inservice valve.
ln that the bench test program did not include inlet piping configurations involving elbow type fittings, CE provided additional information to show that the torque values used for the 18-inch valve stress analysis were conserva-tive regardless of the valve installation configuration.
CE reviewed each in service valve installation to determine if the piping involved an upstream elbow fitting (within 10 pipe diameters) and to determine*
the orientation of the valve shaft relative to the plane of the elbow.
The results of CE's review is summarized in the table below.
Va 1 ve Plant Number Dresden-2
-21
-22
-23
-24 Elbow Upstream Shaft in Plane x x El bow Up st ream Shaft Out of Plane x
No Elbow Effect x
.I.'
Pl ant Dresden-3 Quad Cities-1
(,Juad Cit i es-2 Valve Number
-21
-22
-23
-24
-21
-22
-23
-24
-21
-22
-23
-24 Elbow Upstream Shaft in Plane x x x x x
Elbow Upstream Shaft Out of Plane x
x No Elbow x
x x x x To account for the el bow-shaft out of plane installation configuration (worst case configuration relative to T0 prediction) CE effectively increased Cr (uniform flow) by a factor of 1.5 to establish the torque loads.
In their stress analysis, CE identifed the valve shaft as the critical valve part based on the stress at the disc to shaft pin location.
The maximum stress at this location was calculated to be 11,256 psi-resulting i-n a safety*
factor of 1.33 when using an allowable stress of 15,000 psi.
CE also compared the valve torque loads to the actuator torque output cap-ability and concluded that the actuators are capable of closing the valve during the OBA/LOCA.
4.0 Evaluation*
4.1 The T0 values predicted by CE for the _18-inch 2 Fil valves in the Dresden and Quad Cities plants are very low in comparison to To values given by H. Pratt for the 18-inch 2 Fll valves in the Prarie Island purge and vent system.
Comparing the maximum T0 values predicted, CE predicts a maximum T0 of 2,600 in-lbs where H. Pratt's prediction is approximately 18,000 i n-1 bs.
In addition to the Prarie Island information, torque information available for other valve designs also indicate that GE's To predictions are low for an 18-inch valve.
Based on the above, the staff finds that the T0s predicted by CE for the subject valves are not conservative, and therefore not acceptable to the staff.
4.2 Although CE does not have test data to quantify the effect of piping elbow configurations on Cr (uniform flow) values for the 2 FII design,
.~ '.
.,....... information available from other valve manufacturers indicated that for a given desig~ at the same conditions the ratio of Cr (elbow-shaft in plane) to Cr (uriiform flow) is greater than one and the ratio of Cr (elbow-shaft out of plane) to Cr (uniform flow) is greater than two in some instances.
Based on limited elbow testing information available, the staff believes that where bench tests did not include elbows in the piping configuration a factor of 1.5 times Cr (uniform flow) for an elbow-shaft in-plane configuration and a factor of 3.0 times the CT (uniform flow) for an elbow-shaft out of plane configuration would yield conservative values of T0*
Based on the above, the staff finds that the 1.5 factor used by CE is conser-vative for those valves identified as having straight pipe inlet or elbow-shaft in-plane piping configurations and is not conservative for the three valves identified as having elbow-shaft out of plane configurations.
To be acceptable to the staff, a factor of at least three times Cr (uniform flow) must be used for the three valves having elbow-shaft out of plane configura-tions.
4.3 CE indicated that.the minimum elbow to valve separation distance required to assure uniform approach flow to the valve is 10 pipe diameters.
CE should provide a source reference to justify using 10 Das the minimum.
The staff would accept the separation distances referenced in the Instrument Society of America Standard S39.4.
4.4 Based on the discussions in Section 4.1, 4.2, and 4.3 of this report, the staff finds that CE has not demonstrated that the critical valve parts have sufficient design margins to withstand the pressure related loads of the DBA/LOCA.
- 4.5 Based on the discussions in Section 4.1, 4.2, and 4.3 of this report, the staff also finds that CE has not demonstrated that the actuators are capable of stroking the valve closed during the DBA/LOCA nor has CE demonstrated that the actuators are structurally capable of withstanding the resultant torque loads where those loads act to close the valve disc.
4.6 CE indicated that the seismic qualification of the subject valves is being handled by the Systematic Evaluation Program (SEP) and NRC Bulletin 79-14.
CE should confi~m that the subject valves have been seismically qualified.
4.7 Dresden-2 valves A02-1601-56, -60, -63, and -55, Dresden-3 valves A03-1601-56, -60, -63, and -55, Quad Cities-1 valves AOl-1601-56, -60, -63, and -55, and Quad Cities-2 valves A02-1601-56, -60, -63, and -55 are not included in the review.
The staff assumes that these valves are maintained closed during Modes 1, 2, 3, and 4.
5.0
SUMMARY
The staff has completed its review of the infonnati.on submitted to date concerning
. operability of the 18-inch valves used in the containment purge and vent systems for Oresden, Units 2 and 3 and Quad Cities, Units l and 2.
The staff finds that the information submitted did not demonstrate that these valves have the abi*~ity to close against the buildup of pressure in the event of DBA/LOCA from the full open position. Sections 4.1, 4.2, 4.3, 4.4, 4.5, and 4.6 of the.
evaluation are the basis for these findings.
For this reason, these valves should be sealed closed in accordance with SRP Section 6.2.4.III.6.f. Furthermore; these valves should be verified to be closed at least once every 31 days.
6.0 ACKNOWLEDGEMENT R. J. Wright prepared this Safety Evaluation Date:
November 4, 1983