ML17054A132
| ML17054A132 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/21/1983 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML17054A131 | List: |
| References | |
| NUDOCS 8310060578 | |
| Download: ML17054A132 (10) | |
Text
NINE MILE POINT 1
DOCKET NO. 50-220 DEMONSTRATION OF CONTAINMENT PURGE AND VENT VALVE OPERABILITY 8-24 l.Q ~Ri Demonstration of opef.ability of the containment purge and vent valves, and particularly, 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.
BFV 201-07 BFV 201-08 BFV 201-17 BF V 201-16 BFV 201-09 BFV 201-31 BFV 201-10 BFV 201-32 Valve Size Inches 20 20 20 20 24 24 24 24
~Ty e Butterfly Butterfly Butterfly Butterfly Butterfly Butterfly Butter fly Butterfly Use Suppression chamber purge and vent.
Dry well purge and vent.
Location Outside containment Outside containment Outside containment Outside containment Outside containment Outside containment Outside containment Outside containment The butterfly valves are manufactured by Allis Chalmers.
The 24-inch valves are used for purging and venting the drywell and the 20-inch valves purge and vent the suppression chamber.
All lines have two valves in series; with the inboard valves being air operated and the outboard valves motor operated.
All valves are mechanically blocked for a 50'aximum opening (90'-full open).
The pneumatic operators are manufactured by Bettis and the electric motor operators are made by Limitorque.
Model numbers for the operators are not furnished in the licensee's submittals.
No information is provided in the submittals concerning the pilot solenoid valves.
3.0 Demonstration of 0 erabilit Niagara Mohawk Power Corporation (NMPC) has provided operability demonstration information for the containment purge and vent system isolation valves at thei r Nine Mile Point puclear station in the following submittals:
Reference A -
NMPC letter of January 29,
- 1982, T.
E.
Lampages to D.
B. Vassallo (NRC).
83i0060578 83092i PDR ADQCK 05000220 P
PDR'~
~J t
Reference B - Niagara Mohawk Power Corporation, letter of December 17,
- 1979, D.
P. Disc to T. A. Ippolito (NRC).
Reference C - Allis Chalmers test report for containment isolation valves 9
- i. i980
<<hd ltf A.
3.1 Niagara Mohawk's approach to operability demonstration is based on the test report from Allis-Chalmers (Reference C).
The test report includes a
tabulation for each valve, from 90'open) to 0'closed) in 10'ncrements of the dynamic torque coefficient (Ct), the dynamic torque (TD), the bearing torque (Tb), the combined dynamic and bearing torques (TO =
TD + Tb) and at each increment of angle, the available operator torque.
Although not
- stated, the dynamic torque coefficients are derived from the model testing program; the results of which are presented in the Allis Chalmers report VER-0209.
Allis Chalmers conclusions in the test report (Reference C) are that all valves except for 201-07, -08, and
-17 have operators that are more than adequate, to provide closure during the worst case D.B.A.
Valves 201-07 and
-17 should be blocked at 75'pen, and that the operator for valve 201-08 should either be replaced with a larger unit or reset to provide a faster stroke time.
3.2 Peak drywell containment pressure from the LOCA pressure response curve is assumed at the start of closure from the 90'pen position with a 0 sec delay time..
3.3 The maximum allowable shaft torques are stated as 2,050 fi. l~~ for the 20-inch valves and 2,200ft lbs)for the 24-inch valves.
The largest required operating torques calculated are -1,376)ft-Wbs for the 20-inch valves and
-913 A-lbs for the 24-inch valves.
The. required operating torque is obtained by combining the dynamic torque TD and the bearing torque TB with the negative sign denoting torque assisting valve closure.
The maximum required operating torques occur at the 90'full open) valve position.
The maximum shaft allowable torques although not
- stated, are taken from Table 1 of ANSI/AWWA Standard C504.
4.0 Evaluation
- 4. 1 The bearing torques (Tb) tabulated in the Allis Chalmers test report for valve No. 201-07 have an error in sign.
Tb always opposes valve closure and should be assigned a negative sign.
The combined torque To in this case would therefore be larger than listed in the tabulation for this valve (201-07) since the dynamic torques are all negative and oppose closure.
From the tabulation sheet for this valve (201-07), selecting 50'pen:
TO = -541Ift-lbs TB = 62lft-lbs To = 541
+ 62
= -479(ft-lbs Using the proper sign fdr Tg, To
= -541~+-62)
= -603Ft-1 bs DesPite the increase in To from (-)479~ft-to (-)603f~t-lbs the resul-tant torque margin of 497f~bs is adequate (available operator torque
=
1 100 ft-H)s
).
4.2 The 24-inch valves have large torque margins and are capable of closure against the buildup of containment pressure during the postulated LOCA.
4.3.
The Allis Chalmer test report (Reference C) presents calculated valve torques predicated upon a peak LOCA containment pressure of 34.5 psig occurr-ing when the valve starts closure from full open (90')
and a declining pres-sure ramp for the other valve positions calculated to valve closure.
A "0" second delay is also assumed and the valve closure time used for the analysis is 60 sec.
Since the licensee has chosen to block all the valves at 50'pen, it would be more approproate to calculate the valve torques based on closure from 50'pen.
For~<<p~e recalculating the 20-inch butterfly valve 201-17 assuming 34.5 psig peak LOCA containment pressure and "0" sec delay at the 50'pening corresponding to start of closure, indicates insufficient operator torque capacity as shown below.
Using the standard equation for calculating dynamic torque TP
= CT (03)
ZP where TO = dynamic torque in'ft-lbs CT = the dynamic torque coefficient 0
= disc diameter in ft = 20/12 LP
= pressure drop across the valve in psi.
CT and bP are determined by using the appropriate tables in Allis Chalmers model test report VER-0209.
The Allis Chalmers test report (Reference C) uses Test No.
21 data contained in VER-0209, therefore using the Test No.
21 data the following values are obtained:
P1
= 40 psig Valve angle
= 50'T
= -11.4 and zP
= 29 psi
4 Pl = 30 ps ig Valve angle
=
50'or 34.5 psig Valve angle
= 50' from the above CT = -8.5 and aP
= 24.5 psi CT and hP are obtained by interpol ation.
P1
= 34.5 psig TD = CT (D3) LP CT = -9.81 aP
= 26.53 psi
= -9.81 26.53 203 12
= -1,2091 ftTs Note:
The (-) sign for TD indicates torque opposing closure.
Bearing torque (TB) must also be determined and combined with TD to obtai n the required operating torque (T0).
The standard valve industry equation used to determine bearing torque is TB 4.71 D2dfgP TB = Bearing torque,~ft-lbs D
= Disc diameter in ft d
= Shaft diameter in inches f
= Friction coefficient aP
= Pressure drop across valve in psi.
Using the value of -3.93 from the Allis Chalmers test report:
4.71 D df = -3.93 TB = -3.93 x 26.53
= -104 Required operating torque or TO = TD + TB Note:
The (-) sign indicates torque opposing closure
= -1,209 +~104)
= -1 313]ft-'Ibs The available operator torque for valve No. f01-17 listed in the Allis Chalmers test report (Reference C) is 1,10G ft-lbs! Thus the operator has inadequate torque for closure from 50'pen.
Since the valve is blocked open at 50', concern exists not only with the long-term acceptability but also with meeting the interim operability position.
4.4 The licensee has not provided a stress analysis for critical valve parts and operator mounting hardware that combined LOCA and seismic loads.
However, since the plant received a construction permit prior to
October 27, 1972, these load combinations are not currently required.
- But, Niagara Mohawk Power Corporation should confirm that a seismic analysis was performed for these components.
5.0
~Summer We have completed our review of information submitted to date concerning the operability of containment purge and vent valves for Nine Mile Point l.
Section 4.3 and 4.4 are the basis for the conclusion drawn by the staff.
We find the information submitted failed to demonstrate the ability of both the 20-inch and 24-inch valves to close against the buildup of con-tainment pressure in the event of a LOCA.
For this reason, the purge and vent valves should be sealed closed in accordance with SRP Section 6.2.4, II.6.f.
Furthermore, these valves should be verified to be closed at least once every 3l-days.
Princi al Contributor:
R., Hermann, R. Wright Dated:
September 21, 1983
)