ML20199G185
| ML20199G185 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 04/02/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20199G176 | List: |
| References | |
| NUDOCS 8604090082 | |
| Download: ML20199G185 (7) | |
Text
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UNITED STATES 8
NUCLEAR REGULATORY COMMISSION o
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WASHINGTON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION
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SUPPORTING AMENDMENT NO.37 TO FACILITY OPERATING LICENSE NO. NPF-11 COMMONWEALTH EDtSON COMPANY LA SALLE COUNTY STATION, UNIT 1 DOCKET NO. 50-373
1.0 INTRODUCTION
In Supplement No. 7 to the LaSalle Safety Evaluation Report, we concluded that interim operation was allowed for La Salle Unit 1 since the licensee committed to replace the two 8-inch and eight 26-inch valves used in containment isolation valves prior to startup after the first refueling.
These valves have closure times of 40 seconds which are greater than the 15 seconds approved by the staff.
In addition these valves were blocked from opening greater than 50 degrees since these valves were not, qualified to close from a complete open position during a design basis accident uf loss-of-coolant accident or steam line break, and demonstration of oper-ability is necessary to assure containment isolation. This demonstration is required by Branch Technical Position (BTP), Containment of operability (CSB), 6-4 and Standard Review Plan 3.10 for these containment System Branch purge and vent valves which are not sealed closed during all operational modes.
The vent valves identified as the containment isolation valves in the purge and vent system are as follows:
Valve Number Size Unit 1 (Inches)
Function Location IVQO26 26 Intake Outside Containment IVQO27 26 Intake Outside Containment IVQO29 26 Intake Outside Containment IVQO30 26 Intake Outside Containment IVQO31 26 Exhaust Outside Containment IVQO34 26 Exhaust Outside Containment IVQ036 26 Exhaust Outside Containment IVQ040 26 Exhaust Outside Containment IVQ042 8
Intake Outside Containment IVQ043 8
Intake Outside Containnent IVQO32 2
Bypass Outside Containment IVQO34 2
Bypass Outside Containment IVQ047 2
Bypass Outside Containment IVQ048 2
Bypass Outside Containment IVQ050 2
Bypass Outside Containment IVQ051 2
Bypass Outside Containment IVQ068 2
Bypass Outside Containment 8604090082 860402 PDR ADOCK 05000373 P
. The 8-inch and 26-inch valves are being replaced by Tricentric Butterfly
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Valves which are manufactured by the Clow Corporation. These valves are equipped with air open-spring close actuators manufactured by Bettis.
Model Number NT820-SR3 actuators are installed on the 26-inch valves and NT312-SR3 actuators on the 8-inch valves. Due to their size, operability demonstration of the 2-inch valves is not required, since these 2-inch valves are normally kept closed when the plant is operating.
2.0 EVALUATION The licensee, in its application dated October 2, 1985, indicated that the two 8-inch and the eight 26-inch vent and purge valves are being replaced by high performante air operated butterfly valves which have closure times of equal or less than 30 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 LaSalle are qualified by a combination of test and analysis found in Clow Corporat?on 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 straight run of pipe for both choked and unchoked flow conditions to determine the mass flow an'd aerodynamic torque characteristics. The obtained data were evaluated and subsequently 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 regarding 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 tha Clow valves varied with installed piping conditions such as elbows, tees and reducers. The results of these tests and analyses determined that the upstream elbow effects on the torque characteristics diminished significantly at a distance of 4 pipe diameters and were barely detectable at a distance of 8 l
diameters.
To substantiate the model 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 conditions, that mass flows were as predicted, and that use of the CVAP l
program to predict torques was conservative. The peak measured torque was approximately 65% of the predicted value.
l In the analysis and test performed, the following assumptions have been employed to indicate the conservative approach toward demonstrating operability:
- See Attachment 1.
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a Containment pressure is at a maximum value and full flow has been
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developed prior to initiation of valve closure.
The pressure downstream of the valve is atmospheric.
Worst case upstream pi' ping 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 D# method may be largely conservative as shown by test on 12-inch valve (Vought test).
The methods utilized have been reviewed and are found acceptable to the staff.
Review of the stress analysis (using the ANSYS finite element computer program) for the critical parts of the valve assembly reveals ample margin between the code allowables and the projected values. The elements considered in the Qualification Report, Design Report, and the Structural Analysis Report are summarized in Tables 1 and 2.
An additional conservatism 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 VQO31, the aerodynamic 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 92 days ledage surveillance is no longer required.
Also, since these valves are air-operated no thermal overload bypass functions are required.
In view of the above, the staff finds the information submitted has demonstrated the ability of the valves to close against the buildup of containment 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 l
these valves do not contain resilient seals and are air operated.
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3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes in surveillance requirements. The staff has determined that the amendment involves no significant increase in the amounts, and no l
significant change in tne types, of any effluents that may be released offsite, and that there is no significant increase in individual or l
cumulative occupational radiation exposure. The Connission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has bt.en no public comment on such f
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, finding. Accordingly, this amendment meets the eligibility criteria for
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categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
4.0 CONCLUSION
The Commission made a proposed determinstion that the amendment involves no significant hazards consideration which was published in the Federal Register (50 FR 43023) on October 23, 1985.
No public comments were received, and the state of Illinois did not have any comments.
We have concluded, based on the consideration discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations 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:
J. Lombardo, PWEB Dated: Ayx c., 3,g
-m
Using model test data, dynamic torques are calculated by a computer program, Clow Valve A.;alysis Program (CVAP), developed for use in predicting valve operating characteristics.
In the computer program, mass flow rates are predicted by standard equations for flow through en 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 predicted aerodynamic torque (in-lb)
=
C torque coefficient developed in model tests
=
af 2
pressure differential across the valve (Ib-in )
=
nominal valve diameter (in).
D
=
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 performed 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.
t I
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Table 1.
Summary of Allowable Stresses, 26-inch Valve (Loads per Generic Report)
Allowable Stress Stress Location Material (psi)1 Value (psi)
Valve Body SA 516 17500 6703 GR.70 Disc SA 516 17500 3540 GR.70 Drive Shaft SA 564 34500 3044 Type 630 H-1100 Operator Adapter SA 516 315002 29120 P1 ate GR.70 342003 Adapter M ate SA 193 25000 29120 on Bolts (7 g)
GR.B7 20736 t Cover R ate SA 516 17500 5807 GR.70 Cover R ate SA 193 25000 12276 en Bolts GR.B7 172 x IPer ASME Section III, Tables I-7.1 - I-7.3 (for 7.0 g seismic load).
2Per ASME,Section III, Subsection NC, Article NC3520.
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Evaluated Against.9ay.
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r Tabh 2.
Summary 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 cm Pl ate GR.70
= 17500 1.5.(ASME"S")
25313 om+b
= 26250 Adapter Ma te SA 193 25000 55374 cN Bolts (7 g)
GR.B7 20602 i Cover pl ate SA 516 17500 30 GR.70 Cover Ra te SA 193 25000 4195 cN Bolts GR.B7 172 x 1per ASME Section III, Tables I-7.1 - I-7.3 (for 7.0 g seismic load).
2 lthough the stresses for the adaptor plate bolts ' hown in A
s 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 i
l 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.B7 material is 125,000 l
psi as compared to a 25,000 psi allowable stress.
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