ML20209D096
| ML20209D096 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 08/29/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20209D084 | List: |
| References | |
| NUDOCS 8609090197 | |
| Download: ML20209D096 (7) | |
Text
- K84 9'e g
UNITED STATES E
NUCLEAR REGULATORY COMMISSION g
g
+j WASHINGTON. D. C. 20555
% *** / SAFETY EVALUATION RY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 25 TO FACILITY OPERATING LICENSE NO. NPF-18 COMMON' ALTH EDISON COMPANY
)
LA SALLE COUNTY STATION, UNIT 2 DOCKET NO. 50-374
1.0 INTRODUCTION
In Supplement No. 7 to the La Salle Safety Evaluation Report and License Condition 2.C.(8), we concluded that interim operation was allowed for la Salle Unit 2 since the licensee committed to replace the two 8-inch and eight 26-inch valves used in containment isolation valves prior to startun af ter the first refueling. These valves have closure times of 40 seconds which are creater than the 15 seconds approved by the staff.
In addition these valves were blocked from opening creater than 50 degrees since these valves were not cualified to close from a complete open position during a desian basis accident of loss-of-coolant or steam line break. Demonstration of operability is necessary to assure containment isolation. This demen-stration of operability is required by Branch Technical Position (BTP),
Containment System Branch (CSB), 6-4 and Standard Review Flan 3.10 for these containment purce and vent valves which are not sealed closed durino all operational modes, i
The vent valves identified as the containment isolation valves in the purge and vent system ara as fellows:
l Valve Number Size Unit 2 (Inches)
Function location 2VQO26 26 Intake Outside Containment 2V0027 26 Intake Outside Containment il 2VQO29 26 Intake Outside Containment 2VQO30 26 Intake Outside Containment 2VA031 26 Exhaust Outside Containment 2V0034 26 Exhaust Outside Containment 2V0036 26 Exhaust Outside Containment 2VQ040 26 Exhaust Outside Containment 2V0042 8
Intake Outside Containment 2VQ043 8
Intake Outside Containment 2VQO32 2
Bypass Outside containment 2VQO35 2
Bypass Outside Containment 2VQ047 2
Bypass Outside Containment 2VQ048 2
Rynass Outside Containment 2VQ050 2
Bypass Outside Containment 2VQ051 2
Bynass Outside Containment 2VQ068 2
Bypass Outside Containment I
8609090197 860829 PDR ADOCK 05000374 i
P PDR
The 8-inch and 26-inch valves are being reolaced by Tricentric Butterfly Valves which are manufactured by the Clow Corporation. These valves are eouipped with air open-spring close actuators manufactured by Bettis.
Model Number NT820-SP3 actuators are installed on the 26-inch valves _and NT312-SR3 actuators on the 8-inch valves.
?.0 EVALUATION The licensee, in its acplication dated June II,1986, indicated that the two 8-inch and the eioht 26-inch vent and purge valves are being replaced by high performance air operated butterfly valves which have closure times of equal or less than 10 seconds.
In addition these valves are qualified to close from any position including the full open (90*) position.
The purge and vent valves to be installed at la Salle Unit 2 are qualified by a combination of test and analysis found in Clow Corporation Report No.
7-25-85 entitled " Purge and Vent Operability Qualification Analysis."
Tests were initially performed for 12, 24, 48, and 96-inch scale model valves (scaled to 3-inch pipe size) in a straioht run of pipe for both choked and unchoked flow conditions to determine the mass flow and aero-dynamic toroue characteristics. The obtained data were evaluated and sub-sequently-a computer program *, CVAP, was developed using the measured data base to predict flow and torque values for full size valves in a straight run of pipe. To address the concerns reoarding the effect that the upstream configuration would have on the dynamic torque characteristics, a second series of model tests and analyses were performed to determine how the aerodynamic torque characteristics of the Clow valves varied with installed piping conditions such as elbows, tees and reducers. The results of these tests and analyses demonstrated that the upstream elbow effects on the torque characteristics diminished sionificantly at a distance of 4 pipe diameters and were barely detectable at a distance of 8 diameters.
To substantiate the mode tests and analysis, a full size 12-inch valve assembly operational test under choked flow conditions was performed. The test results showed that the valve would operate under the choked flow con-ditions, that mass flows were as predicted, and that use of the CVAP program to predict torques was conservative. The peak measured torque was approxi-mately 65% of the predicted value.,
In the analysis and test performed, the following assumptions have been employed to indicate the conservative approach toward demonstrating operability:
Containment pressure is at a maximum value and full flow has been developed prior to initiation of valve closure.
- See Attachment 1.
i
The pressure downstream of the valve is atmospheric.
Worst case upstream piping configuration (mitered elbow worse than radius elbow) and distance considered.
Torque coefficients used in the CVAP program are worst case values.
Scaling of torques to larger size values by the D3 method may be largely conservative as shown by test en IP-inch valve (Vought testi.
The methods utilized have been reviewed and are found acceptable to the staff.
Review of the stress analysis (using the ANSYS finite element computer pro-gram) for the critical parts of the valve assembly reveals ample margin between the code allowables and the pro,iected values. The elements con-sidered in the Qualification Report, Design Report, and the Structural Analysis Report are summarized in Tables 1 and 2.
An additional conserva-tism in the analysis is the 45 psid pressure assumed across the valve.
The Bettis actuators are shown in the submittal to have a maximum spring torque at 90 full open positive.
For valve V0031, the aerod.vnamic torques for the first 3 to 5' from full open resist closure. However, for all valves a positive torque margin exists i.e., actuator torque delivered is greater than any of the forces resisting closure.
In addition, these new Clow valves do not contain resilient seals; and therefore, the once per 97 days leakage surveillance is no longer required.
Also, since these valves are air-operated no thermal overload bypass func-tions are required.
In view of the above, the staff finds the information submitted has demon-strated the ability of the valves to close against the buildup of contain-ment pressure in the event of a design basis accident. Therefore, Technical Specifications 3.6.1.8, 4.6.1.8 and associated basis 3/4.6.1.8 can be revised to remove the 50 limit on valve opening. In addition, Technical Specification 4.6.1.8.2 is deleted and Technical Specification 3.8.3.3 is revised to delete these valves from Table 3.8.3.3-1 since these valves do not contain resilient seals and are air-operated. With respect to adding these valves at the first refueling outage, this is in accordance with the license condition.
3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in the installation and use of a facility component located within the restricted area as defined in 10 CFR Part 70 and changes in surveillance requirements. The staff has determined that this amendment involves no significant increase in the amounts, and no significant chance in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumula-tive cccupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards
. l consideration and there has been no public comment en such finding. Accord-ingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.2?(b),
no environmental impact Ftatement or environmental assessment need be prepared in connection with the issuance of this amendment.
4.0 CONCLtlSION The Commission made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (51 FR 27279) on Wednesday, July 30, 1986, and consulted with the state of Illinois. No public comments were received, and the state of Illinois did not have any comments.
i The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not he endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regula-tions and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
A. Bournia, BWP Project Directorate No. 3, DBL Dated:
August 29, 1986
l Sumary of Allowable Stresses. 26-inch Valve Table 1.
(Loads per Generic Report)
Stress Allowable Stress Material (psi)2 Value (psi)
Location 6703 Valve Body SA 516 17500 GR.70 3540 SA 516 17500 Disc GR.70 3044 Drive Shaft SA 564 34500 Type 630 H-1100 2
29120 SA 516 31500 Operator Mapter 342003 GR.70 P1 ate 29120 on SA 193 25000 20736 x Mapter P1 ate Bolts (7 g)
GR.B7 5807 SA 516 17500 Cover M ate GR.70 12276 en SA 193 25000 172 x Cover R ate GR.B7 Bolts 2 er ASME Section III, Tables I-7.1 - I-7.3 (for 7.0 g P
seismic load).
2Per ASME,Section III, Subsection NC, Article NC3520.
3 Evaluated Against.9ay.
)
Table 2.
Sumary of Allowable Stresses, 6-inch Valve (Loads per Generic Report)
Allowable Stress Stress Location Material (psi)1 Value (psi)
Valve Body SA 516 17500 7088 GR.70 Disc SA 516 17500 6767 GR.70 Drive Shaft SA 564 34550 27610 Type 630 H-1100 Operator Adapter SA 516 1 (ASME "S")
2718 om P1 ate GR.70
= 17500 4
1.5 (ASME "S")
25313 omb
= 26250 Adapter Pla te SA 193 25000 55374 on Bolts (7 g)
GR.B7 20602 2 Cover P1 ate SA 516 17500 30 GR.70 Cover Pinte SA 193 25000 4195 oN Bolts GR.B7 172 x PerASMESectionIII,TablesI-7.1-I-7.3(for7.0p 2
seismic load).
. i.
2 lthough the stresses for the adaptor plate bolts ishown in A
column four of the table are higher than the allowable stress values shown in column three, the bolt stresses are within the ASME Code limits as specified in ASME Section III, Appendix XVII Subarticle 2460. The allowable bolt stresses per Appendix XVII are based on the ultimate tensile strength of the material as shown in Appendix 1. Table I-7.3.
The ultimate tensile strength of SA 193 GR.87 material is 125.000 psi as compared to a 25,000 psi allowable stress.
i Using model test data, dynamic torques are calculated by a computer program, Clow Valve Analysis Program (CVAP), developed for use in predicting valve sperating characteristics.
In the computer program, mass flow rates are predicted by standard equations for flow through an ideal converging nozzle adjusted with coefficients developed in the tests. Torques are predicted on the basis of the equation:
3 T=CaPD T
y where:
T predictedaerodynamictorque(in-lb)
=
C torque coefficient developed in model tests h
==
2 pressure differential across the valve (lb-in )
D nominal valve diameter (in).
=
y The power of three used in the equation and the CVAP program is a derived value obtained by use of the equations for a general control volume. A test perfomed on a full size 12-inch valve indicated that torques were approximately 65% of the values obtained for the same valve from the CVAP program, thus demonstrating additional conservatism in the analysis.
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