ML20151H834
| ML20151H834 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 04/08/1988 |
| From: | Larson C NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation |
| References | |
| IEB-85-003, IEB-85-3, NUDOCS 8804200554 | |
| Download: ML20151H834 (9) | |
Text
'
, i, Northern States Power Company 414 Nicollet Malt Minnaapoks. Minnesota 55401 Telephone (612) 330 5500 April 8, 1988 IE Bulletin 85-03 Director of Nuclear Reactor Regulation U S Nuclear Regulatory Commission Attn:
Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 IE BULLETIN 85-03 FINAL RESPONSE Actions required by NRC Bulletin 85-03 have now been completed at the Prairie Island Nuclear Generating Plant.
The purpose of this letter is to provide a final report of actions taken in response to the Bulletin.
During the Prairie Island Unit 1,
1987 refueling outage and the Prairie Island Unit 2,
1988 refueling outage, maintenance, modi-fication and testing was performed on 42 motor operated valves (21 per unit) as required by NRC IEB 85-03 "Motor Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings".
This program at Prairie Island was implemented to ensure that valve operator switches are selected, set and maintained to arsure operational readiness of the motor-operated valves.
Prairie Island's program consisted of:
1.
A conservative determination of the maximum differential pressure expected during normal and abnormal events for both opening and closing the valves as defined in the Bulletin.
2.
From the above data, revised switch settings and switch setting methods were established.
Open torque switch settings were established using the M0 VATS calculation techniques or the maximum torque switch setting as provided by Limitorque.
If the Limitorque calculated open torque switch setting is more conservative than the MOVATS setting, it is used.
Closed torque switch settings were calculated using only the Limitorque calculation technique.
MOVATS calculations appear to be overly conservative and may cause excessive seat / disc wear, gg 8804200554 890408 I)
PDR ADOCK 05000282 m
ma
A L
D rectg j 8l i
Northem States Power Company
,1t Page 2 i
The open torque switch bypass was set at values greater than 20% full valve stroke.
This setting assures that the open torque switch will not inadvertently de-energize the motor during the large valve unseating loads when in a. differential pressure condition.
The red light indication (indicating that the valve is not fully closed) was set to provide the operator with the earliest indica-tion of valve movement.
To facilitate this the red light was rewired to a separate limit switch rotor than the torque switch bypass via modification 86L951.
The green light indication (indicating that the valve is not fully open) and the open limit are both on the same limit switch rotor.
This rotor is set such th&t the valve does not electrically backseat nor coast into the backseat.
All valves within the scope of the Bulletin do not utilize a closed limit.
Thermal overload settings for the motor operated valve intermittent duty motors are sized at 70% of the full load current.
This setting provides motor protection should it run in excess of the allowable period (15 min) at full load current.
Furthermore, during valve setup and testing the frequency of valve stroke cycles wac limited to prevent motor damage.
Refer to Table I for a summary of actuator data.
3.
Torque switch and limit switch setting methods were changed.
Rather that. using the original Limitorque data, each spring pack / torque switch was calibrated using MOVATS supplied equipment.
Each torque switch was setup, first being balanced, at a voltage equivalent to the desired stem thrust.
Limit switches and torque switch bypasses were setup based on the time scale of the resultant signatures.
In conjunction with the resetting of switches, each actuator was subject to detailed inspection and preventive maintenance.
The process for each actuator inspection consisted of:
a)
As found valve stroke timing b)
As found valve current and power signatures c)
Motor actuator isolation for work d)
Motor megger e)
Check tightness of actuator bolts to valve yoke f)
Lubrication of valve stem g)
Verification that the locking nut is staked
f
't Northem States Power Company Apri 8
19 8 Page 3 h)
Cleaning of grease relief tube 1)
Housing / handwheel gasket inspection j)
Grease sampling k)
Recording as-found torque switch settings 1)
Limit switch compartment inspection including wire insulation, wire harness heat, limit switch rotor condition and vent / drain plugs in place m)
Determination of limit switch compartment heaters n)
Changing limit switch grease o).
Cleaning and gauging of limit and torque switch contacts p)
Rewiring the red light indication to limit switch rotor #4 q)
Torque switch free operation check r)
Cleaning of operator spring pack s)
Spring pack / torque switch calibration and switch setup t)
Static differential pressure testing on all valves using a high capacity hydropump or equivalent while taking actuator signatures u)
Full flow differential pressure testing on pump discharge valves while taking actuator signatures.
Differential pressure testing has been performed on all the valves.
i When the testing was not performed at the design pressure, linear extrapolations were performed to assure adequate margin exists for valve operability.
Furthermore, open torque switches are bypassed for more than 20% of the valve stroke to assure unseating loads do not make the valves inoperable.
Pump discharge valves were also subjected to a full flow test using the system pump.
In this test, valves were tested going in the closed direction proving that they can close with flow under the seat.
During the differential pressure testing, all of the valves performed as designed with no further switch resetting required.
4.
New procedures were developed and existing procedures revised to reflect the new philosophies in switch settings.
An ongoing program is in place to rewire all motor actuators to allow for independent setting of the open torque switch bypass and the valve position indication.
All safety related motor actuators, including the Bulletin valves, are now incorporated into the preventive maintenance program which includes signature analysis.
The preven-tive maintenance procedures aggressively incorporate recommendations from the industry when applicable.
, ~..,_ _ _ -. _ -. _ _.. _. _ _ _.. _ _. _. _ - _
'l ect f
s h 6mm p
98 Page 4 To further ensure switch settings are maintained, valves are stroke timed in accordance with the ASME Section XI program.
Valve stroke times are trended to easily detect any degradation.
If maintenance is performed that could affect the valve stem thrust or actuator functions, necessary testing is performed to assure valve operability.
l Please contact us if you have any questions related to the actions l
we.have take n response to NRC Bulletin 85-03.
C E Lars n Vice Pres at Nuclear Generation c: Regional Administrator, Region III NRC Sr Resident Inspector, NRC NRR Project Manager, NRC G Charnoff Attachments i
l
2 UNITED STATES NUCLEAR REGUIATORY COMMISSION NORTHERN-STATES POWER COMPANY PRAIRIE IS1AND NUCLEAR GENERATING PIANT DOCKET NO. 50-282 50-306
- FINAL RESPONSE TO NRC COMPLIANCE 3ULLETIN 85-03 Northern States Power Company, a Minnesota corporation, with this letter is submitting information requested by NRC Compliance Bulletin 85-03.
This letter contains no restricted or other defense information.
NORTHERN STATES POWER COMPANY By
<M C E La son l
Vice Pre t Nuclear Generation On this k day of
_/[L
,/ @ before me a notary public in and
/
for said County, persfnally appeared C E Larson, Vice President Nuc-lear Generation, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made in it are true and that it is not interposed for delay.
A r:k-(1M1
~.
r a
MARCIA K taCORE NOTARY PUBUC-MINNES0TA HEMEPIN COUNTY My (tw.aca bpres Sept 24.1983 se:::::::::::::::::::::::::::::::::
I 6
N l
I 1
TABLE 1 IEB 85-03 ACTUATOR DATA
SUMMARY
Page 1 of 4 IEB 85-03 FINAL SWITCH EVAL
VALVE /
OPEN/CIDSE (PSI)
ADJUSTMENT BULLETIN AS FOUND VALVE IDENTIFICATION /
VALVE (S) 1 ACTUATOR l
FUNCTION l
PSI l OPEN/CLOSE I OPEN/CLOSE (#) l OPEN/CIDSE 1 OPERABILITY I REMARKS MV-32333 i Linatorque, i Condensate to l
14/14 1
144/11 i
N/A i
3651/2975 l Valves cycled i Rotork actuator replaced with l SMB-000 l Auxiliary i
l l
l with condensate l Limitorque actuator. AP testing MV-32335 1 1700 RPM i Feedwater Pump i
i 132/11 1
1 1790/1553 I storage tank i proved adequate margin is available I Suction l
l l
1 l head AP across I for valve operability. Furthermore, MV-32336 l 1
l l
138/138 l
l 2150/1961 l
them.
l T/S bypass set at greater than 20%
l l
l l
l l
l Satisfactory.
l valve stroke.
MV-32345 I l
l l
138/138 I
I 2033/1666 l
l l
l l
l l
I I
MV-32025 j Limitorque, i Cooltog Water to i 135/135 1
103/103 l
2789/3506 1
3325/3313 1 32G30 did not i Valves tested with cooling water i SMB-000 l Auxiliary l
l l
l l cycle with AP on I header pressure. Maximum thrust at MV-32027 l 1700 RPM l Feedwater Pump I
i 103/103 1
4223/2789 l
3190/3180 l initial attempt. I reduced pressure was sufficiently l
l Suction i
l l
l l Handwbeel was I low to not warrant full AP test MV-32026 1 1
I i
118/118 I
4223/4223 1
3985/3958 l available.
I pressure. Furthermore, T/S bypass l
I l
l l
l l Other three l set at greater than 20% valve stroke.
MV-32030 1 l
l l
118/118 l
2789/1355 1
4065/3559 i valves were i
I I
l l
l l
l satis f acto ry.
l I
I l
l l
I l
1 MV-320lb i Limitorque. 1 Main Steam Supplyl 1086/1086 l 980,450/980,l 7448/7448 1
6311/4606 i T/S settings l Reduced pressure AP was used.
I SMB-00 I to Turbine Driven!
1 450 l
l l were high enough l Thrust at lower pressure, MV-32017 1 1700 RPM l Auxiliary l
l 980,450/980,1 6690/6690 1
8167/3291 l to preclude
! extrapolated to 1086# still provides I Feedwater Pump i
! 450 I
i i inadvertent valvel adequate margin for valve MV-32019 l l
l l 600,820,930/l 6690/6690 1
7909/5169 I inoperability.
l operability. Furthermore, T/S bypass I
I l 950,820,600 I l
l T/S bypass set I set at greater than 20% valve stroke.
MV-32020 1 1
1 I 980,450/980,1 8207/8207 I
8363/4892 l af ter valve I
i l
l 450 l
l l unseating.
1 I
l 1
I l
l l
l MV-32238 i Limatorque, i Turbine Driven 1 1086/1780 11100/720,10201 8687/8687 l
14055/13003 1 T/S settings i Static AP tests performed with valve 1 SMB-00 l Auxiliary I
l l
l l were high enough l going open at 1100 psi; Satisf actory MV-32239 l 1700 RPM i Feedwater Pump i
11100/720,1020l 13368/13368 l
14383/12717 l to preclude valvel performance.
I I Discharge to i
l l
l l inoperability.
I Full flow AP tests performed at NV-32?46 l l Steam Generators 1 11100/680,390 1 11028/11028 l
14689/12215 i T/S bypass set I reduced pressure with valve going l
i I
i l
l l after valve I closed. Adequate margin exists for MV-32247 I i
i 11100/670,480 1 11028/11028 l
14326/12260 l unseating.
I full AP.
AP developed is a function i
l i
i l
l i of the turbine vs. pump curves.
I I
I f
I I
I i
- As found settings are calculated from Limitorque obtained data - accuracy does not include T/S balancing.
r.
TABLE 1 IEB 85-03 ACTCATOR DATA
SUMMARY
Page 2 of 4 EVAL
- SWITCH SETTING.
FINAL SWITCH IEB 85-03 SETTINGS IN AP MAX TEST AP PRIOR TO RESPONSE TO TEST METHOD DESCRIPTION /
VALVE /
OPEN/CLOSE (PSI)
ADJUSTMENT BULLETIN AS FOUND VALVE IDENTIFICATION /
VALUE(S) l ACTUATOR l
FUNCTION l
PSI I OPEN/CLOSE I OPEN/CLOSE (#) l OPEN/CLOSE l OPERABILITY l REMARKS l
1 l
i l
l l
l MV-32381 l Limitorque, 1 Motor Driven l 1086/1720 11100/1540, l
4905/4905 l
6053/6812 1 T/S settings l Static AP tests performed with valve l SMB-000 l Auxiliary 1
11420 l
I were high enough I going open at 1100 psi; Satisfactor:
MV-32382 l 1700 RPM i Feedwater Pump l
11100/1550, l
4905/4905 1
6675/6393 I to preclude valve] perfo rmance.
1 I Discharge to 1
11510 l
l 1 inoperability.
I Full flow AP tests performed at MV-32383 l l Steam Generator i 11100/1665, l
4905/4905 1
6518/6141 j T/S bypass set I reduced pressure with valves going l
l l
11630 I
I t af ter valve l closed. Adequate margin exists for MU-32384 l l
l
[1100/1660, 4705/4905 1
6455/6390 l unseating.
I full AP.
AP developed is a functior l
l
]
11450 l
l l
l of the pump suction pressure (i.e.
l l
l l
l l
l l did not want to put cooling water i
i 1
i l
l l into Stm Gen.)
MV-32081 l Limitorque, i Safety Injection i 23\\/23$
j 200/200 l
4688/4688 l 12184/10283 l With static BAST l aP test at 200 psid performed.
I SMB-00 1 Pump (s) Suction l l
l
[
l head valves l Satisfactory performance of all MU-32082 1 3550 RPM i from Boric Acid l l
[
4638/4688 l
9816/5333 l operated i valves was observed. Valves were I Storage Tank i
l l
l l satisfactorily. I reset for 200 psid. Original MU-32184 I l
l l
l 4688/4668 l
9918/7482 l T/S bypass set I settings were for static head.
l l
l l
l l
l af ter valve l
MV-32185 1 l
l l
1 6129/6129 l
8644/7200 l unseating.
1 I
l l
l l
I I
I MV-32079 i Limatorque, 1 Safety Injection 1 32h/32 1
200/200 1
5520/5520 l
9104/8669 l With static RWST l aP test at 200 psid performed.
I SMB-0 l Pump (s) Suction i l
l l
l head valves i Satisfactory performance of all MV-320&O I 3550 RPM l from Refueling l
l l
4908/4908 1
9098/8857 l operated i valves was observed. Valves were l
l Water Storage i
l l
l I satisfactoril. l reset for 200 psid. Original MV-32182 l l Tank l
l l
4664/6620 l
8427/3802 l T/S bypass set I settings were for static head.
l l
1 l
l l
1 between hammer-l MV-32183 I I
l l
l 4664/4664 l
7874/10286 l blow and valve l
I i
l l
l l
l unseating on l
l l
l l
l l
l 32182. Torque I
l l
I i
l i
l switches set highl l
l l
l l
l l enough for static l l
l l
l l
l l (325#) condition I i
l l
l l
l l to assure l
1 l
l l
l l
l operability.
l I
I I
I I
I I
I
- As found settings are calculated from Limitorque obtained data - accuracy does not include T/S balancing.
i l
'e
- e
.i TABLE 1 IEB 85-03 ACTUATOR DATA S129 TART p
3,g 4
-l
(
IEB 85-03 FINAL SWITCH l
EVAL
l VALVE /
OPEN/CIDSE (PSI)
ADJUSTMENT BULLETIN AS FOUND VALVE IDENTIFICATION /
VALVE (S) l ACTUATOR I
FUNCTION l
PSI I OPEN/CLOSE I OPEN/CLOSE (#) ! OPEN/CLOSE I OPERABILITT l REMARKS l
1 l
i l
i l
l l
f MV-32162 i Limitorque, 1 Safety Injection i 325/325 l 200/200 1
4578/4578 l
4954/2470 l With static RWST ( AP test at 200 psid performed.
1 l
1 SMB-00 1 Pump (s) Suction l l
l l
l head valves
[ Satisfactory performance of all l
MV-32163 1 3550 RPM i
l i
1 5711/5711 1
5232/2645 I operated l valves was observed. Valves were
.J t
l l
l l
l l
l satisfactorily. l reset for 200 psid. Original l
MV-32190 I l
l l
1 3444/3444 l
4240/2789 l T/S bypass set l settings were for static head.
i i
I I
l l
l l Past valve l
MV-32191 I l
l l
[
3444/3444 1
4548/2781 l unseating. T/S l l
l l
l l
l l set above valve l l
l l
l l
l l unseating load.
I l
l l
l l
l l
l l
[
t i
i i
i i
i I
l MV-32074 i Limitorque, l Reactor Safety 1 2510/2510 1700,1400,21001 7064/7064 l
11190/8103 l As found T/S
'l Full AP test in open direction.
1 SMB-00 l Injection l
l& 2525/2220 l l.
I settings were l Satisfactory. Full flow AP test in MV-32177 l 1700 RPM l Hot Leg Isolation l 1700,1400,21001 9350/9350 1
13437/7553 l above AP test l closed direction proved adequate l
l l
l 12230 & 2525/ l l
l thrusts. Adequate l. margin exists for the closed l
l l
12230 l
l l T/S bypass i direction.
.l 1
l l
l l
l l protection was l
1 l
[
]
l l
l provided.
l l
l l
l 1
l l
i MV-32172 l Limitorque, l Reactor Safety l 2510/2465 1 700, 1400, i 16543/16543 1 13112/11755 l Adequate T/S I Full AP test in open direction.
I SMB-00 l Injection hot i
! 2100 & 2525/l l
l bypass protection!. Satisfactory. Full flow AP test in r
l 1700 RPM l Leg Isolation l
l 2250 & 2150 l l
l was provided.
I closed direction proved adequate
(
l i
l l
l l
l In addition, T/S l margin exists for the closed MV-32170 l l
l l 700, 1400, i 13323/13323 l 15129/11445 I settings were 1 direction.
1 l
l 2100 & 2525/l l
I well above valve 1 l
i l
l 2230 & 2190 l l
l hammerblow l
I I
l l
l l
l tiirusts.
l l
MV-32069 I l
l l 700, 1400, l 16543/13323 l l'.793/11088 l l
i I
I l 2100 & 2525/l l
l 1
l 1
I l
l 2120 & 2210 l l
l l
l l
l l
1 1
1 I
MV-32067 I l
l l 700, 1400, i 19763/6882 1 14094/11702 l l
I i
i 1 2100 & 2525/l l
l I
i l
l 2080 & 2220 l l
l l
l I
I I
I I
I
- As found settings are calculated from Limitorque obtained data - accuracy does not include T/S balancing.
4 R
og s
- e TABLE I IEB 85-03 ACTUATOR DATA
SUMMARY
Page 4 of 4 IEB 85-03 FINAL SWITCH EVAL
VALVE /
OPEN/CLOSE (PSI)
ADJUSTMENT BULLETIN AS FOUND VALVE IDENTIFICATI0':/
VALVE (S) l ACTUATOR I
FUNCTION l
PSI l OPEN/CLOSE l OPEN/CLGSE (#) l OPEN/CLOSE l OPERABILITY
! REMARKS i
i i
i i
l i
MV-32202 i Limi to r<;ue. I Safety Injection i 2287 /2287)1 2300/-
13844/13844 l
15437/10828 l Adequate T/S I Full AP test performed in open l SMB-00 1 Pump (s) Mini-Flowl l
l l
l bypass protectioni stroke with satisfactory MV-32203 1 1700 RPM l Recirculation I
2300/-
l 13844/13844 1
14345/11864 I was provided.
I performance. Test in closing mode I Valves l
l l
l l In addition, T/S l not performed because it would MV-32204 l l
l l
2300/-
l 10971/10971 l
14695/11393 I settings were i potentially cause pump damage.
l l
l l
l l
l well above valve l Based on test results on MV-32172, Ifi-32205 l l
I l
2300/-
l 10971/10971 1
14669/11452 l hammerblow l 32170, 32069 and 32067 adequate l
l l
l l
l l
thrusts.
I margin exists for closing.
- As found settings are calculated from Limitorque obtained data - accuracy does not include T/S balancing.