ML17054B890
| ML17054B890 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/10/1985 |
| From: | Butler W Office of Nuclear Reactor Regulation |
| To: | Hooten B NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 8509230461 | |
| Download: ML17054B890 (20) | |
Text
Docket No. 50-410 SEP 10
]ging Mr. B. G. Hooten Executive Director of Nuclear Operations Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, N.Y. 13202
Dear her. Hooten:
SUBJECT:
OPERABILITY OF CONTAINMENT PURGE AND VENT VALVES FOR NINE MILE POINT 2 The staff has completed it's review of your January 25, 1985 submittal on con-tainment purge valves at Nine Mile Point 2 as supplemented by your March 29, 1985 letter.
The results of our review are discussed in the enclosed evaluation.
In summary, the staff's findings are as follows:
2) 3)
For valves AOV-106 (14 inch), AOV-108 (14 inch) and AOV-109 (12 inch),
satisfactory demonstration has been furnished that these valves can close from a fully opened position (90') against the rise in contain-ment pressure following onset of a DBA/LOCA; f
For valve AOV-104 (14 inch), satisfactory demonstration has been furnished as above, subject to implementation of certain modifications as discussed in the enclosed evaluation; and For valves AOV-105 (12 inch), AOV-107 (12 inch), AOV-110 (14 inch),
and AOV-111 (12 inch), satisfactory demonstration has not been furnished.
Accordingly, Niagara Mohawk should provide either a
commitment that these valves will be sealed closed in accordance with SRP Section 6.2.4 II-6.f or additional qualification information.
In order to support a fuel load date of February 1986, the additional commitment/information relative to Item (3) above should be submitted no later than November 15, 1985.
Also by this date, Niagara Mohawk should provide a
commitment to complete implementation of the modifications referred to in Item (2) above, prior to initial criticality.
Any questions concerning the enclosed evaluation should be forwarded to the Licensing Project Manager, Mary F. Haughey (301) 492-7897.
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Enclosure:
As stated cc:
See next, page Walter R. Butler, Chief Licensing Branch No.
2 Division of Licensing DISTRIBUTION:
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SEP 10 1985 Docket No. 50-410 Mr. B. G. Hooten Executive Director of Nuclear Operations Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, N.Y. 13202
Dear Mr. Hooten:
SUBJECT:
OPERABILITY OF CONTAINMENT PURGE AND VENT VALVES FOR NINE MILE POINT 2 The staff has completed it's review of your January 25, 1985 submittal on con-tainment purge valves at Nine Mile Point 2 as supplemented by your March 29, 1985 letter.
The results of our review are discussed in the enclosed evaluation.
In suIIWIary, the staff's findings are as follows:
2) 3)
For valves AOV-106 (14 inch), AOV-108 (14 inch) and AOV-109 (12 inch),
satisfactory demonstration has been furnished that these valves can close from a fully opened position (90')- against the rise in contain-ment pressure following onset of a DBA/LOCA; For valve AOV-104 (14 inch), satisfactory demonstration has been furnished as above, subject to implementation of certain modifications as discussed in the enclosed evaluation; and For valves AOV-105 (12 inch), AOV-107 (12 inch), AOV-110 (14 inch),
and AOV-ill (12 inch), satisfactory demonstration has not been furnished.
Accordingly, Niagara Mohawk should provide either a
commitment that these valves will be sealed closed in accordance with SRP Section 6.2.4 II-6.f or additional qualification information.
In order to support a fuel load date of February 1986, the additional commitment/information relative to Item (3) above should be submitted no later than November 15, 1985.
Also by this date, Niagara Mohawk should provide a
commitment to complete implementation of the modifications referred to in Item (2) above, prior to initial criticality.
Any questions concerning the enclosed evaluation should be forwarded to the Licensing Project Manager, Mary F. Haughey (301) 492-7897.
Enclosure:
As stated cc:
See next page Walter R. Butler, 'Chief Licensing Branch No.
2 Division of Licensing
1
Mr. B. G. Hooten Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Unit 2 CC:
Mr. Troy B. Conner, Jr.,
Esq.
Conner E Wetterhahn Suite 1050 1747 Pennsylvania Avenue.,
N.W.
Washington, D.C.
20006 Richard Goldsmith Syracuse University College of Law E. I. White Hall Campus
- Syracuse, New York 12223 Ezra I. Bialik Assistant Attorney General Environmental Protection Bureau New York State Department of Law 2 World Trade Center New York, New York 10047 Resident Inspector Nine Mile Point Nuclear Power Station P. 0.
Box 99
- Lycoming, New York 13093 Mr. John W. Keib, Esq.
Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202.
Mr. James Linville U. S. Nuclear Regulatory Coranission Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 Norman Rademacher, Licensing Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202 Regional Administrator, Region I U.S. Nuclear Regulatory Co(mission 631 Park Avenue King of Prussia, Pennsylvania 19406
Enclosure NINE MILE POINT NUCLEAR STATION, UNIT 2 K
.50-220 DEMONSTRATION OF CONTAINMENT PURGE AND VENT VALVE OPERABILITY Demonstration of operability of the containment purge and vent valves, partic-ularly the ability of these valves to close during a design basis accident, is necessary to assure containment isolation.
This demonstration of operability is required by BTP CSB 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 Descri tion of Pur e and Vent Valves The valves identified as the containment isolation valves in the purge and vent system are as follows:
Valve Ta No.
Valve Size Ihches 0 erator T
e Valve Location AOV<<104
. AOV-106 AOV-108 AOV-110 AOV-105 AOV-107 AOV-109 AOV-111 14 14 14 14 12 12 12 12
Air-Open, Air-Open, Air-Open, Air-Open, Air-Open, Air-Open, Air-Open, Air-Open, Spring-Cl ose Spring-Close Spring-Close Spring-Close Spring-Close Spring-Close Spring-Close Spring-Close Outside Containment Inside Containment Inside Containment Outside Containment Outside Containment Inside Containment Inside Containment Outside Containment The valves are all butterfly valves manufactured by Posi-Seal International (PSI) of North Stonington, Connecticut and are furnished with Bettis (air-open, spring-close)
Hodel Number N721C-SR80-H3HW actuators.
- 3. 0 Demonstration of 0 erabi 1 it 3.1 Niagara Mohawk Power Corporation (NHPC) has provided purge and vent valve operability demonstration information for the 12-inch and 14-inch purge and vent valves at the Nine Mile Point Nuclear Station, Unit 2 in their letters of January 25, 1985 and Harch 29, 1985 from C.
V. Hangan (NHPC) to A. Schwencer (NRC) and the following reports.
Reference A - Posi-Seal International Report No. 33375SL-001 entitled "LOCA and Sei smic Analysis."
Reference 8 - Posi-Seal International Seismic Functional Test 19157ST-01.
Reference C - Posi-Seal International Nuclear Seismic Analysis 19157Sg-01.
I
2 3.2 Enclosure 3 of Reference A describes model testing performed by PSI on valve sizes from 1-1/2 inch through 14 inch for both preferred and nonpre-ferred flow to obtain hydrodynamic to'rque factors that are used in calculating dynamic torques for all sizes and classes of trunnion valves.
Based upon the flow testing performed at PSI, the following general observations concerning hydrodynamic torque of trunnion valves can be made:
1.
For preferred flow, the hydrodynamic torque will always act to close the valve.
2.
For nonpreferred flow, the hydrodynamic torque will oppose valve closure from the 90'ull open position through 70'o 80'pen (the exact loca-tion varies with valve class).
Beyond this point to 0'closed),
the hydrodynamic torque will act to close the valve.
3.
Except for the 90'alve opening where the hydrodynamic torque factors are of equal magnitude for both preferred and nonpreferred flow, but of oppo-site sign, the nonpreferred hydrodynamic torque factors are considerably less in magnitude than those for preferred flow.
Posi-Seal International in Reference A derives aerodynamic torque equations for steam and water using the data from the hydrodynamic model testing program.
A constant peak containment pressure during the postulated LOCA of 45 psig is assumed for all the valves for conservatism since the larger the pressure drop, the larger the aerodynamic torques acting on the valve.
Actually, with valve (drywell) closure within 5 seconds (Tech.
Spec.) the containment pressure will have increased only to approximately 6 psig based on the LOCA containment pressure response curve.
Single valve closure is assumed for con-servatism since simultaneous valve closure would reduce the aerodynamic torque and flow.
3.3 Flow conditions as the valves close against the buildup of pressure in containment due to a
LOCA, are analyzed in Appendix B to Reference A "Oeter-mination of Flow Conditions."
Since the makeup of the media is not known, three different conditions are analyzed to determine which condition results in the largest aerodynamic torques.
This condition is then used in the remainder of the analysis.
The three conditions investigated are as follows:
Condition Media Air Air Steam Temperature (oF 135 340 292 (Saturated}
Condition 2 results in the largest aerodynamic torques and is assumed in the analysis as worst case.
3.3 Stress analysis results for the valve critical parts are shown on page 7
of Reference A.
Calculated stresses for the actuator bolt, bracket bolt,
- bracket, valve neck, stem and disc pin are compared to Section III ASME Boiler and Pressure Code allowable stresses.
3.4 Appendices C,
D and E to Reference A entitled "Determination of Closing Times" presents the results of a closure time analysis based on the equation shown below:
where:
T
= T
+ T
+ T
+ T TTO flow air spring packing and seal bearing
+ T TTTO Tf1 ow Tair Tspring Tpacking
=
and seal Tbearing
=
The net torque tending to open the valve (equals zero when the valve starts to close).
The torque due to aerodynamic flow caused by the LOCA.
The torque exert by the actuator as a result of the air acting on the actuator piston tending to open the valve.
The torque exerted by the actuator spring tending to close the valve.
Torque of the packing and the seal resisting the closihg motion of the val.ve.
The seal torque does not take effect until the disc begins to seal which occurs at approximately 3'rom fully closed.
The running torque of the packing is approximately
.6 times the break away torque.
Torque due to the zP acting across the valve which forces the stem/disc assembly into the bearings.
Closing times are calculated for each valve for opening angles of 90'nd 70'o closure.
For those valves installed in the nonpreferred direction, the closure times are also determined for the preferred direction of installation.
3.5 Seismic qualification analysis and seismic functional test data are provided by PSI in Reference B and Reference C.
3.6 Posi-Seal recommends based on their analysis that valve numbers AOV-105,
-104, and -110 presently installed in the nonpreferred direction either be reoriented in the preferred direction with the stem side of the disc upstream and the retaining ring downstream or be mechanically limited to a 70'aximum valve opening.
The reason for this is that the LOCA-induced dynamic loads oppose closure for these valv'es installed in the nonpreferred direction and exceed the actuator spring capability to close the valve.
Also recommended for valve number AOV-ill is a reorientation to the preferred direction and a
70'imitation on valve opening to preclude disc pin overstressing.
4.0 Evaluation 4.1 Posi-Seal's approach to dynamic torque predictions for the 12-inch and 14-inch'urge and vent valves at Nine Mile Point. Unit 2 is based on torque factors derived from hydrodynamic model tests coupled with torque equations
(Reference A) that determine the aerodynamic torques under LOCA conditions.
Conservative assumptions used by PSI for dynamic torque predictions include a
constant peak containment pressure during closure, selection of worst case media (air at 340'F), single valve closure (other valve failed open) and no credit taken for downstream pressure drops in piping.
The staff's findings (summari zed in Table
- 1) for each valve are as follows:
Valve Number AOV-104 (14 inch.
Operability for this valve is demon-strated pending smp ementatson of PSI recommendations to reorient the valve in the preferred direction or limit the opening angle to 70'.
Valve Numbers AOV-106 and -108 14 inch.
Operability demonstrated for ot va ves as insta e.
Valve Numbers AOV-110 (14 inch and AOV-105 (12 inch.
The staff concurs w>th P
s recommendatsons to reorient the va ve sn the preferred direc-tion or limit the opening to 70'n order not to exceed the actuator spring torque capability.
However, the disc pin calculated shear stress at the 80'pening angle exceeds the allowable shear stress as shown in Section 4.3.
Valve Number AOV-107 12 inch).
The disc pin calculated shear stress at t e 8
opening ang e exceeds the allowable shear stress.
(See Table 1
and Section 4.3.)
Valve Number AOV-109 12 inch.
Operability is demonstrated for thi s va ve as snsta ed.
Valve Number AOV-ll 12 inch).
The staff concurs with PSI's recommenda-t>ons to reorient t e va ve sn the preferred direction and limit the opening to 70'n order not to exceed the actuator spring torque capabil-ity.
However, the calculated shear stress at 70'xceeds the allowable shear stress..
(See Table 1 and Section 4.3.)
4.2 The largest LOCA induced valve torque of 9,584 in-lbs occurs at a valve closure angle of 80'or 14-inch valve number AOV-110 and compared to the Bettis N721C-SR80 actuator maximum allowable torque of 22,500 in-lbs provides an adequate structural margin.
4.3 The results of the valve critical parts stress analysis performed by PS I are shown in Table 2 taken from Reference A.
For the valve openings and flow directions analyzed, the allowable stresses shown in this table are not ex-ceeded by the calculated
- stresses, except for valve number AOV-111 which shows a disc pin overstress in shear at an 80'alve opening.
For this reason, PSI recommends that the valve be restricted to a maximum opening of 70'here the calculated disc pin stress is less than the allowable shear stress.
The staff finds the stress analysis results acceptable for each critical part analyzed.
However, the staff does not accept the allowable shear stress used for the disc pin.
The allowable shear stress used by PSI is 31,680 psi which is un-acceptably high compared to the 21,120 psi determined by the staff using the ASNE 8oiler and Pressure Vessel Code.
Table I Eva luatlon Sunmary Valve Number and SIze
( Inch)
AOY-104 (14)
AOY-106 (14)
AOY-108 (14)
AOY"110 (14)
AOV-105 (12)
AOV-107 (12)
AOV-109 (12)
Pre-ferred Non-preferred Insta I I ed Configuration Closure Against LOCA Torque Will NIII Not Close Close Disc Pin PSI Overstressed Recomme~da-(See tlon Section 4 3)
Comments Operability demonstrated pending im-plementation of PSI recommendations (3) ~
Operability denonstrated for valve as installed, Same as AOY-106
'perabi Ilty not demonstrated, Dlsc pin overstressed at 80'nd preferred orientation.
Stress may be within allowable at 70' Same as AV-110.
Operabl llty not demonstrated.
Disc pin overstressed at 80' Stress may-be within allowable at 70' Operablllty demonstrated for valve as Installed, AOV-111 (I2) 2CIosure from 90'ful I open) and 'Installed conf lguratlon.
LOCA-induced aerodynamic torque exceeds actuator capabl I Ity.
Reorient valve to preferred d'Irectlon or 70'ngle I Imitation 70'imit
& reor'lent Disc pin overstressed at 70'nd pre-ferred direction.
Stress may be within the allowable shear stress at 70'nd the nonpreterred direction,
Table 2 Results LOCA and Selsmlc Stresses (PSI)
Actuator Bolt Bracket Bolt Bracket Valve Neck Sten Disc Pln Size Valve Flow Tag No.
(In,)
Opening Dl rection Cele.
Alla>
Cele.
Allow Cele.
Al Icw Ca Ic.
Alla>
Cele.
Allov
- Gale, Alice AOV"106 AOV-104 AOV-108 AOV"110 AOV-I07 AOV-105 AOV-109 AOV-111 14 14 14 14 12 12 12 12 80'0'0'0'0'0'0'0'0'referred 15019 Nonpreferred 17018 Preferred 14788 Preferred 18168 Nonpreferred 14795 Nonpreferred 15107 Preferred 14376 Preferred 16632 Preferred 15265 37500 37500 37500 37500 37500 37500 37500 37500 37500 20400 37500 21557 37500 20255 37500 24240 37500 2'1162 37500 25495 31500 20817 37500 26431 37500 25590 37500 3765 18900 3983 18900 3701 18900 5150 18900 3313 18900
" 3443 18900 3179 18900 3903 18900 3492 18900 1722 23400 1805 23400 1705 23400 2166 23400 9640 23400 3118 23400 9551 23400 3376 23400 3198 23400 14522 52800 16761 52800 13902 52800 21138 52800 13005 52800 14258 52800 11297 52800 20203 52800 14885 52800 14808 31680 17614 31680 14035 31680 23002, 31680 22977 31680 25716 31680 19139 31680 38943 31680 27178 31680
~
I'
~0 7
I Using Table I-7.2 for Class 2,
3 components from the ASME Boiler and Pressure Vessel
- Code,Section III Appendix I, the allowable stress in tension (S) at 400'F for the SA564 GR630 H1075 disc pin material is 35,200 psi.
The allow-able stress in shear therefore is 0.6 x 35,000 or 21,120 psi and is exceeded by the calculated disc pin stresses for valve numbers AOV-110, -107, -105 and
-111.
Table 2 entitled "Evaluation Summary" lists the analysis results and staff comments regarding operability demonstration.
4.4 Seismic qualification of the 12-inch and 14-inch purge and vent valves at the Nine Mile Point Nuclear Station, Unit 2 is addressed in References B and C.
Reference C demonstrates by analysis that the valves are seismically qualified, with natural frequencies greater than 33 Hz, seismic stresses smaller than the allowables, and small actuator deflections.
Reference B con-tains test information that demonstrates that the valves retain the ability to operate in the intended manner when subjected to a static force equivalent in magnitude to the seismic load and applied at the actuator center of gravity.
5.0 Summary We have completed our review of the information submitted to date concerning the operability of the 12-inch and 14-inch valves used in the containment purge and vent system at the Nine Mile Point, Nuclear Station, Unit 2.
We find that the information submitted demonstrates the ability of valve numbers AOV-106, -108 (14 inch),
and -109 (12 inch) to close against the rise in con-tainment pressure in the. event of a'DBA/LOCA from the 90'frill: open) open-ing.
Operability under DBA/LOCA conditions has also been demonstrated for valve number AOY-104 (14 inch) pending implementation of PS! recommendations to reorient the valve in the preferred direction or mechanically limit'he valve opening to 70' We also find that the information submitted fails to demonstrate the ability of valve numbers AOV-110 (14 inch) and AOV-105, -107, and -111 (12 inch) to close against the rise in containment pressure in the event of a DBA/LOCA.
Section 4.3 of the evaluation is the basis for the con-clusion by the staff.
For thi s reason, these valves should be sealed closed in accordance with SRP Section 6.2.4.II-6.f.
Furthermore, these valves should be verified sealed closed at least once every 31 days.
C
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