ML20090E432: Difference between revisions
StriderTol (talk | contribs) StriderTol Bot insert |
StriderTol (talk | contribs) StriderTol Bot change |
||
| Line 17: | Line 17: | ||
=Text= | =Text= | ||
{{#Wiki_filter:: | {{#Wiki_filter:: | ||
7 n | 7 (j | ||
g n | |||
One Figrs Com calth Ealson s | |||
/ | |||
tionti Ptara. Clucago Ittmois | tionti Ptara. Clucago Ittmois | ||
/ Addrest Reply to: Post Offics Box 767 | |||
-^ | |||
November 20, 1975 | p Chicago, Illinois 60600 BBS Ltr. #769-75 Dres' den Nuc1 car Power Station R.R. #1 604)(y,. | ||
Mc,rris, Illinois November 20, 1975 f | |||
f li'[,. | |||
i | |||
- [/ O[p, ' ';l3 7. ! | |||
g | .'N o | ||
Mr. James G. Keppler, Regional Director - | ~ s, O..; | ||
j " S -u | g Mr. James G. Keppler, Regional Director - | ||
Directorate of Regulatory Operation - Region III | g j " S -u 8 | ||
Directorate of Regulatory Operation - Region III Of' 'J' A'q j(h ("'{W{Tij[V, U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 | |||
==SUBJECT:== | ==SUBJECT:== | ||
| Line 38: | Line 40: | ||
==References:== | ==References:== | ||
: 1) Regulatory Guide 1.16 Rev. 1 Appendix A | : 1) Regulatory Guide 1.16 Rev. 1 Appendix A | ||
: 2) Notification of Region III of U.S. Nuclear Regulatory Commission Telephone: Region III Headquarters, Duty Office. 0855 hours on November 16, 1975 | : 2) Notification of Region III of U.S. Nuclear Regulatory Commission Telephone: | ||
Telegram: J. Keppler, 1250 hours on November 17, 1975 Report Number: 50-237/1975-52 Report Date: November 20, 1975 Cccurrence Date: November 16, 1975 IDENTIFICATION OF OCCURRENCE Main steam isolation valve A0 2-203-1C closed in less than 3.0 seconds, which is contrary to section 3.7.D.1 of the Technical Specifications. | Region III Headquarters, Duty Office. 0855 hours on November 16, 1975 Telegram: | ||
J. Keppler, 1250 hours on November 17, 1975 Report Number: 50-237/1975-52 Report Date: November 20, 1975 Cccurrence Date: November 16, 1975 IDENTIFICATION OF OCCURRENCE Main steam isolation valve A0 2-203-1C closed in less than 3.0 seconds, which is contrary to section 3.7.D.1 of the Technical Specifications. | |||
CONDITIONS PRIOR TO OCCURRENCE Unit-2 was in the Run mode at a power level of 428 MWt and 103 MWe. Quarterly surveillance testing of the main steam isolation valves was in progress. | CONDITIONS PRIOR TO OCCURRENCE Unit-2 was in the Run mode at a power level of 428 MWt and 103 MWe. Quarterly surveillance testing of the main steam isolation valves was in progress. | ||
DESCRIPTION OF OCCURRENCE At approximately 0330 hours on November 16, 1975, main steam isolation valve 203-1C exhibited a closure time of 2.7 seconds'. Technical Specifications require that for closure time t, 10 sec. < t < 5.0 sec. The valve was Icft in the isolated position, and the unit was subsequently shut down. | DESCRIPTION OF OCCURRENCE At approximately 0330 hours on November 16, 1975, main steam isolation valve 203-1C exhibited a closure time of 2.7 seconds'. Technical Specifications require that for closure time t, 10 sec. < t < 5.0 sec. | ||
13509 8303310593 751120 PDR ADOCK 05000237 8 | The valve was Icft in the isolated position, and the unit was subsequently shut down. | ||
pyg | 13509 8303310593 751120 PDR ADOCK 05000237 8 | ||
^ | |||
pyg m | |||
r- | r-zq Mr. ~Jimea G. K pr | ||
zq | -2, Novrmb2r 20, 1975 | ||
,DESICNATION OF APPARENT CAUSE OF OCCURRENCE (Component Failure) | |||
Inspection of valve 203-1C revealed that the hydraulic biced-off valve was out of adjustment. The bleed-off valve controls the rate of oil exchange across the valve operator piston, thus controlling the valve's rate of closure. The biced-off valve adjustment discrepancy was attributed to normal valve wear. | |||
Inspection of valve 203-1C revealed that the hydraulic biced-off valve was out of adjustment. The bleed-off valve controls the rate of oil exchange across the valve operator piston, thus controlling the valve's rate of closure. The biced-off valve adjustment discrepancy was attributed to normal valve wear. | ANALYSIS OF OCCURRENCE All eight main steam isolation valves had been satisfactorily tested on September 9, 1975. Had a reactor scram occurred while valve 203-1C was out of adjustment, the resultant premature isolation of the "C" main stean line would have presented minimal se;fety implications. | ||
ANALYSIS OF OCCURRENCE All eight main steam isolation valves had been satisfactorily tested on September 9, 1975. Had a reactor scram occurred while valve 203-1C was out of adjustment, the resultant premature isolation of the "C" main stean line would have presented minimal se;fety implications. | The remaining three steam lines would have effectively equalized any pressure spike, thereby precluding the possibility of a significant transient within the reactor vessel. This' occurrence did not endanger plant personnel or the general public. | ||
CORRECTIVE AtrION Following shutdown of the unit, the bleed-off valve on 203-lc was readjusted to bring the valve closure time within specifications. At 1720 hours on November 16, valve 203+1C was successfully tested three times, with an average closure time of 3.6 seconds. The valve was then returned to service in preparation for unit start-up. | CORRECTIVE AtrION Following shutdown of the unit, the bleed-off valve on 203-lc was readjusted to bring the valve closure time within specifications. | ||
At 1720 hours on November 16, valve 203+1C was successfully tested three times, with an average closure time of 3.6 seconds. | |||
The valve was then returned to service in preparation for unit start-up. | |||
FAILURE DATA Four similar isolation valve timing. failures have occurred at Dresden since-1970. | FAILURE DATA Four similar isolation valve timing. failures have occurred at Dresden since-1970. | ||
The main steam isolation valves are air-operated, 20" Y-pattern globe. valves, manufactured by Crane Valve Co.- | The main steam isolation valves are air-operated, 20" Y-pattern globe. valves, manufactured by Crane Valve Co.- | ||
l ^- | l ^- | ||
ij) M% | |||
/ | |||
Sthphenson Superintendeet-BBS: CAR:aw | |||
e 4 | . File /NRC e | ||
e 4 | |||
r G | |||
r | r | ||
>}} | |||
Latest revision as of 14:21, 13 December 2024
| ML20090E432 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 11/20/1975 |
| From: | Stephenson B COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 13509, 769-75, AO-50-237-75-52, NUDOCS 8303310593 | |
| Download: ML20090E432 (2) | |
Text
7 (j
g n
One Figrs Com calth Ealson s
/
tionti Ptara. Clucago Ittmois
/ Addrest Reply to: Post Offics Box 767
-^
p Chicago, Illinois 60600 BBS Ltr. #769-75 Dres' den Nuc1 car Power Station R.R. #1 604)(y,.
Mc,rris, Illinois November 20, 1975 f
f li'[,.
i
- [/ O[p, ' ';l3 7. !
.'N o
~ s, O..;
g Mr. James G. Keppler, Regional Director -
g j " S -u 8
Directorate of Regulatory Operation - Region III Of' 'J' A'q j(h ("'{W{Tij[V, U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137
SUBJECT:
REPORT OF ABNORMAL OCCURRENCE PER SECEION 6.6. A 0F Tile TEC11NICAL SPECIFICATIONS RAPID CLOSURE OF UNIT-2 MAIN STEAM ISOLATION VALVE 203-lC
References:
- 1) Regulatory Guide 1.16 Rev. 1 Appendix A
- 2) Notification of Region III of U.S. Nuclear Regulatory Commission Telephone:
Region III Headquarters, Duty Office. 0855 hours0.0099 days <br />0.238 hours <br />0.00141 weeks <br />3.253275e-4 months <br /> on November 16, 1975 Telegram:
J. Keppler, 1250 hours0.0145 days <br />0.347 hours <br />0.00207 weeks <br />4.75625e-4 months <br /> on November 17, 1975 Report Number: 50-237/1975-52 Report Date: November 20, 1975 Cccurrence Date: November 16, 1975 IDENTIFICATION OF OCCURRENCE Main steam isolation valve A0 2-203-1C closed in less than 3.0 seconds, which is contrary to section 3.7.D.1 of the Technical Specifications.
CONDITIONS PRIOR TO OCCURRENCE Unit-2 was in the Run mode at a power level of 428 MWt and 103 MWe. Quarterly surveillance testing of the main steam isolation valves was in progress.
DESCRIPTION OF OCCURRENCE At approximately 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br /> on November 16, 1975, main steam isolation valve 203-1C exhibited a closure time of 2.7 seconds'. Technical Specifications require that for closure time t, 10 sec. < t < 5.0 sec.
The valve was Icft in the isolated position, and the unit was subsequently shut down.
13509 8303310593 751120 PDR ADOCK 05000237 8
^
pyg m
r-zq Mr. ~Jimea G. K pr
-2, Novrmb2r 20, 1975
,DESICNATION OF APPARENT CAUSE OF OCCURRENCE (Component Failure)
Inspection of valve 203-1C revealed that the hydraulic biced-off valve was out of adjustment. The bleed-off valve controls the rate of oil exchange across the valve operator piston, thus controlling the valve's rate of closure. The biced-off valve adjustment discrepancy was attributed to normal valve wear.
ANALYSIS OF OCCURRENCE All eight main steam isolation valves had been satisfactorily tested on September 9, 1975. Had a reactor scram occurred while valve 203-1C was out of adjustment, the resultant premature isolation of the "C" main stean line would have presented minimal se;fety implications.
The remaining three steam lines would have effectively equalized any pressure spike, thereby precluding the possibility of a significant transient within the reactor vessel. This' occurrence did not endanger plant personnel or the general public.
CORRECTIVE AtrION Following shutdown of the unit, the bleed-off valve on 203-lc was readjusted to bring the valve closure time within specifications.
At 1720 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.5446e-4 months <br /> on November 16, valve 203+1C was successfully tested three times, with an average closure time of 3.6 seconds.
The valve was then returned to service in preparation for unit start-up.
FAILURE DATA Four similar isolation valve timing. failures have occurred at Dresden since-1970.
The main steam isolation valves are air-operated, 20" Y-pattern globe. valves, manufactured by Crane Valve Co.-
l ^-
ij) M%
/
Sthphenson Superintendeet-BBS: CAR:aw
. File /NRC e
e 4
r G
r
>