ML18150A171: Difference between revisions

From kanterella
Jump to navigation Jump to search
(Created page by program invented by StriderTol)
(StriderTol Bot change)
 
(4 intermediate revisions by the same user not shown)
Line 3: Line 3:
| issue date = 06/12/1987
| issue date = 06/12/1987
| title = LER 87-011-00:on 870516,low Flow Reactor Trip Occurred. Caused by Hot Leg Loop Stop Valve Stem Failure Permitting Disc to Drop,Blocking Loop Flow.Procedure Revised to Reduce Stress on Valve stem.W/870612 Ltr
| title = LER 87-011-00:on 870516,low Flow Reactor Trip Occurred. Caused by Hot Leg Loop Stop Valve Stem Failure Permitting Disc to Drop,Blocking Loop Flow.Procedure Revised to Reduce Stress on Valve stem.W/870612 Ltr
| author name = SAUNDERS R F
| author name = Saunders R
| author affiliation = VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
| author affiliation = VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
| addressee name =  
| addressee name =  
Line 16: Line 16:


=Text=
=Text=
{{#Wiki_filter:POW 28-06-01 *.* -NIIC Form 391} U.S. NUCLEAR REGULATORY COMMISSION 19-83) APPROVED OMII NO. 3150-0104 LICENSEE EVENT REPORT (LER) EXPIRES: 8/31185 FACILITY NAME 11) I DOCKET NUMBER 121 I PAG~ 131 Surrv Power Station. Unit 1 o I 5 I o I o I o I 2 I R In 1 OF n I -:i TITLE 1'1 Reactor Trip on Low RCS. Flow Due to Failure of Loop Stop Valve. EVENT DATE 16) LER NUMBER 161 REPORT DATE 171 OTHER FACILITIES INVOLVED (Ill MONTH* DAY YEAR YEAR /{ SEQUENTIAL
{{#Wiki_filter:POW 28-06-01 U.S. NUCLEAR REGULATORY COMMISSION NIIC Form 391}
() REVSSION MONTH DAY YEAR FACILITY NAMES DOCKET NUMBERISl NUMBER NUMBER *.-01s1010101 I I o Is , I 6 011 -ol ,1 , -o I o ol6 112 sl1 0151010101 I I 8 7 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Ch.c:k on, or mor, of th1 following)
19-83)                                                                                                                                                                                                         APPROVED OMII NO. 3150-0104 EXPIRES: 8/31185 LICENSEE EVENT REPORT (LER)
(111 MODE (II) N 20.402(bl 20.40ll(cl X II0.73(o)(21Civl 73.7,Cbl -I----POWER 20.406(0)(1 )Ii) II0.31Cc)l11 II0.73(o)(2llvl 73.7,Ccl LEVEL ----(10) ,, 0 I 0 20.406(0)(1  
FACILITY NAME 11)                                                                                                                                                                           IoDOCKET NUMBER 121 I 5 I o I o I o I 2 I R In I
)(Iii 60.311(c) 121 60.73(oll211vlll OTHER (S~ify in Abstr,ct -----b1tow ,nd in Text. NRC Form ., ...... :*.**:*. *.*.:;.* .*.;.;.; 20.40llloll1  
1 OF PAG~ 131 nI            -:i Surrv Power Station. Unit 1 TITLE 1'1 Reactor Trip on Low RCS. Flow Due to Failure of Loop Stop Valve.
)(Ill) 50.73(01121111 II0.7311112llwiiillAI 366A) 1*.*.*.* *.*.*.;. *:-::*:*:*:*
EVENT DATE 16)                                           LER NUMBER 161                                 REPORT DATE 171                                               OTHER FACILITIES INVOLVED (Ill DOCKET NUMBERISl MONTH*                 DAY               YEAR           YEAR   /{     SEQUENTIAL NUMBER      () REVSSION NUMBER MONTH                     DAY               YEAR                 FACILITY NAMES 01s1010101                                     I           I o Is , I 6                                   8 7 011
.*.*-*. :*.*.*. :*.*.*:* .*.*-*.; , ... , .... --:*:*:*:*:*:
                                                                      - ol           ,1 , - o I o ol6                                 112               sl1                                                         0151010101                                     I           I THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR                                           §: (Ch.c:k on, or mor, of th1 following) (111 OPERATING MODE (II)
.... ,. *.* .. *.* .*.-*.;.*.;.*
N         20.402(bl                                     20.40ll(cl                                             X     II0.73(o)(21Civl                                 73.7,Cbl I-POWER LEVEL 20.406(0)(1 )Ii)                             II0.31Cc)l11
20.40ll(o)(1 lflvl li0.73(111211ill II0.731oll211wlllllBI , ...........
                                                                                                                                                                      --      II0.73(o)(2llvl 73.7,Ccl OTHER (S~ify in Abstr,ct (10)                         0 I0                20.406(0)(1 )(Iii                             60.311(c) 121                                                 60.73(oll211vlll b1tow ,nd in Text. NRC Form 1*.*.*.*
...... * *:*:* .-.*.*: ----, ...... , .*.*.*.**.-.
20.40llloll1 )(Ill)                           50.73(01121111
*:*:*::-.*
                                                                                                                                                                      -      II0.7311112llwiiillAI                           366A) 20.40ll(o)(1 lflvl 20.40llloll1 llvl li0.73(111211ill
*.;.*.-.;.-.
                                                                                                                &0.73(oll2lliiil
:*:* 20.40llloll1 llvl &0.73(oll2lliiil 60.73(oll211xl LICENSEE CONTACT FOR THIS LER (121 NAME TELEPHONE NUMBER AREA CODE R. F. Saunders, Station Manager 0 1 o, q 3 I 51 7 I -13 I 1 I 8 14 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (131 MANUFAC-REPORTABLE . ;.;;.;. .*.**.; . ;,;.;.*.*  
                                                                                                                                                                      -      II0.731oll211wlllllBI 60.73(oll211xl LICENSEE CONTACT FOR THIS LER (121 NAME                                                                                                                                                                                                             TELEPHONE NUMBER AREA CODE R.           F. Saunders, Station Manager                                                                                                                                     0 1 o, q 3 I 51 7 I - 13 I 1 I 8 14 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (131 REPORTABLE         .;.;;.;. .*.**.;. ;,;.;.*.* ;.*..*.*                                                 MANUFAC-MANUFAC-
;.* .. *.* MANUFAC-R ~~o~;:~iE  
                                                                                                                    .*.**.*. .*.*,*.*. *.*.:*.*                  SYSTEM        COMPONENT CAUSE            SYSTEM                    COMPONENT TURER          TO NPRDS CAUSE                                      TURER          R ~~o~;:~iE ':J::1111:1::11:1:11111:1::1111:J:f     i!iiliil!i:iiiji
':J::1111:1::11:1:11111:1::1111:J:f i!iiliil!i:iiiji CAUSE SYSTEM COMPONENT TURER TO NPRDS .*.**.* . . *.*,*.*. *.*.:*.* CAUSE SYSTEM COMPONENT TURER *.* .. *.* *.*:*.*.*
                                                                                                              *=*=**=- :-:**.*. .....*.*.* *:*::*:
*.*::-:-*:*
y             .....,.; ;.;.,;.; ......,.;..,.,*.*.                                                             ,*                           *:*:         .;.;                 .;.
*=*=**=-:-:**.*. ..... *.*.* *:*::*: ;.;.-.* . .;,; :-:,::,:*
X              AIB                  I 1S1V I               A1319 11                                                                                      I           I   I   I         I   I I                   I I       I         I     I     I                         ..
.;,::,:-:,:,:, ... ;,; .. ;,; :; ;.;._.;. ;.;,;, X AIB I 1S1V I A1319 11 y ..... ,.; ;.;.,;.; ...... ,.; . . ,.,*.*. I I I I I I ,* *:*: . ;.; .; . *.* .. *.-*.* .. *.* *.*. ........ *.*.*:*:**:*:
                                                                                                                                  ;           ,;,;*.;.*.*.           I            I I      I        I    I    I                        ;.-.     :*:**:*:     ....   .*:*.*:*: :,:-:-:,:
*:* :*:*:*:,:
SUPPLEMENTAL REPORT EXPECTED 114)                                                                                                                 MONTH           DAY                 YEAR EXPECTED lxl           YES (If yos, compl*r* EXPECTED SUBMISSION DATE/
,;,;*,;. I I I I I I I *:*:*: *:*::*:* .... ;.;,; :-:**:* I I I I I I I *:* *:; .. *.* *.*: ,;.; .. ;,; ;., .... ; .-.*,;.:, ,;,;*.;.*.*.  
ABSTRACT (Limit to 1400 SPIJCSs. i,tJ,, *PfJroxim,ttJly fifts6n singts-spacs typswrirrsn lim,s} (16) h                NO SUBMISSION DATE 1151 018          310                  817 On May 16, 1987 at 0824 hours, with Unit 1 at 100% power, a low flow reactor trip occurred when "A"loop reactor coolant system (RCS) {EI IS-AB} flow decreased to 47%.                                                                                               Following the reactor trip, the source range channels {EIIS-DET} did not automatically reinstate. All other protection and control systems functioned properly. Operators followed appropriate plant procedures and stabilized the plant following the reactor trip.
;.-. :*:**:*: .... . *:*.*:*: :,:-:-:,:
This event occurred when the. II A" hot leg loop stop valve (EIIS-ISV} stem failed, permitting the disc to drop, partially blocking loop flow. A detailed metallurgical analysis is being performed to determine the failure mode and mechanism of the valve stem. The preliminary report indicates that failure was due to stress or fatigue. To reduce the stress on the valve stem, the operating procedure is being revised to normally operate the valves*off the backseat. The failure of source range channels to reinstate was due to the under compensation of the intermediate range channel NI-36. The source range channels were manually reinstated, and technicians readjusted the intermediate range compensating voltage.
SUPPLEMENTAL REPORT EXPECTED 114) MONTH DAY YEAR EXPECTED h NO SUBMISSION lxl YES (If yos, compl*r* EXPECTED SUBMISSION DATE/ DATE 1151 018 310 817 ABSTRACT (Limit to 1400 SPIJCSs. i,tJ,, *PfJroxim,ttJly fifts6n singts-spacs typswrirrsn lim,s} (16) On May 16, 1987 at 0824 hours, with Unit 1 at 100% power, a low flow reactor trip occurred when "A"loop reactor coolant system (RCS) {EI IS-AB} flow decreased to 47%. Following the reactor trip, the source range channels {EIIS-DET}
8706230353 870612 Itl'-
did not automatically reinstate.
PDR            ADOCK 05000280                                                                                                                                                          \     (\
All other protection and control systems functioned properly.
s                                         PDR NRC Form 386 19-83)
Operators followed appropriate plant procedures and stabilized the plant following the reactor trip. This event occurred when the. II A" hot leg loop stop valve (EIIS-ISV}
stem failed, permitting the disc to drop, partially blocking loop flow. A detailed metallurgical analysis is being performed to determine the failure mode and mechanism of the valve stem. The preliminary report indicates that failure was due to stress or fatigue. To reduce the stress on the valve stem, the operating procedure is being revised to normally operate the valves*off the backseat.
The failure of source range channels to reinstate was due to the under compensation of the intermediate range channel NI-36. The source range channels were manually reinstated, and technicians readjusted the intermediate range compensating voltage. Itl'-,..,;.., 8706230353 870612 \ ( \ PDR ADOCK 05000280 s PDR NRC Form 386 19-83)
NRC l'orm 366A * (9-83) FACILITY NAME (1) POW 28-06-01 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION APPROVED 0MB NO. 3150--0104 EXPIRES: 8/31/88 DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) YEAR ::::::::::
SEQUENTIAL
::::::::::*
REVISION *::::::::::
NUMBER .'."."."." NUMBER Surry Power Station, Unit 1 o 1s Io Io Io I 2 I 81 O 81 7 -011 I 1 -0 I O Ol 2 OF O I 3 TEXT '" more IP"C9 i& "'flUired, U&tl *dditiona/
NRC Form 36flA '&/ (17) NAC FOAM 366A (9-83) 1.0 Description of the Event On May 16, 1987 at 0824 hours, with Unit 1 at 100% power, a low flow reactor trip occurred when "A" loop reactor coolant system {EIIS-AB} (RCS) flow decreased to 47%. Following the reactor trip, the source range channels {EIIS-DET}
did not automatically reinstate.
All other protection and control systems functioned properly.
Operators followed appropriate plant procedures and stabilized the plant following the reactor trip. 2.0 Safety Consequences and Implications The low flow reactor trip automatically trips the reactor to maintain sufficient margin above a DNBR of 1.3 with a loss of RCS flow. The complete loss of flow in one loop from a reactor power of 100% (2441 MWt) with three loops operating is an analyzed event. During the event, "A" loop flow was maintained at approximately 47% and total core flow remained at 84%. A confirmatory analysis performed by Nuclear Engineering concluded that DNBR was maintained above the accident analysis value of 1.3. In addition, all other safety related systems remained operable during the event, and plant parameters remained well within the bounds of the accident analysis.
Therefore this event did not constitute
*an unreviewed safety ques*tion and the health and safety of the public were not affected.


===3.0 Cause===
POW 28-06-01 NRC l'orm 366A
The cause of this event was a failure of the "A" RCS hot leg loop stop valve (MOV-1590)
* U.S. NUCLEAR REGULATORY COMMISSION (9-83)
{EIIS-ISV}.
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION                                         APPROVED 0MB NO. 3150--0104 EXPIRES: 8/31/88 FACILITY NAME (1)                                                        DOCKET NUMBER (2)                                                             PAGE (3)
The valve stern failed, permitting the disc to drop, partially blocking the loop flow. The valve stern is being analyzed for failure mode and mechanism.
LER NUMBER (6)
A supplemental LER will be submitted when this analysis is completed.
YEAR  :::::::::: SEQUENTIAL ::::::::::* REVISION
The preliminary report indicates that failure was due to fatigue or stress. The failure of the source range channels to reinstate was due to the under compensation of the intermediate range channel NI-36.
                                                                                                        *::::::::::   NUMBER   .'."."."." NUMBER Surry Power Station, Unit 1 o 1s Io Io Io I 2 I 81 O 81 7 -           011  I1 -             0  I O Ol 2  OF    OI 3 TEXT '" more IP"C9 i& "'flUired, U&tl *dditiona/ NRC Form 36flA '&/ (17) 1.0            Description of the Event On May 16, 1987 at 0824 hours, with Unit 1 at 100% power, a low flow reactor trip occurred when "A" loop reactor coolant system {EIIS-AB} (RCS) flow decreased to 47%. Following the reactor trip, the source range channels {EIIS-DET} did not automatically reinstate.
NRC Form 366A. (9-831 FACILITY NAME (1) POW 28-06-01 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION APPROVED 0MB NO. 3150-0104 EXPIRES: 8/31 /88 Dq<:KET NUMBER (2) YEAR LER NUMBER (6) ::::::::::
All other protection and control systems functioned properly. Operators followed appropriate plant procedures and stabilized the plant following the reactor trip.
SEQUENTIAL
2.0            Safety Consequences and Implications The low flow reactor trip automatically trips the reactor to maintain sufficient margin above a DNBR of 1.3 with a loss of RCS flow. The complete loss of flow in one loop from a reactor power of 100% (2441 MWt) with three loops operating is an analyzed event.
:::::::::::
During the event, "A" loop flow was maintained at approximately 47% and total core flow remained at 84%.
REVISION ::::::::::
A confirmatory analysis performed by Nuclear Engineering concluded that DNBR was maintained above the accident analysis value of 1.3. In addition, all other safety related systems remained operable during the event, and plant parameters remained well within the bounds of the accident analysis. Therefore this event did not constitute *an unreviewed safety ques*tion and the health and safety of the public were not affected.
NUMBER ::::::::::
3.0           Cause The cause of this event was a failure of the "A" RCS hot leg loop stop valve (MOV-1590) {EIIS-ISV}. The valve stern failed, permitting the disc to drop, partially blocking the loop flow.
NUMBER PAGE (3) Surry Power Station, Unit 1 0 1s101010121a10 817 -01111-olo oh &deg;Fo 1~ TEXT /ff more /J/NJCl1 is n,quired, U/ltl 11dditionsl NRC Form 3lil!iA '*) (17) NRC FORM 366A (9-83) 4.0 Inunediate Corrective Action The Operators performed all appropriate emergency procedures and function restoration procedures to ensure the plant was returned to a stable condition.
The valve stern is being analyzed for failure mode and mechanism. A supplemental LER will be submitted when this analysis is completed. The preliminary report indicates that failure was due to fatigue or stress.
This included manually reinstating the source range channels.
The failure of the source range channels to reinstate was due to the under compensation of the intermediate range channel NI-36.
Also, the STA performed the critical safety function status tree review to ensure specific plant parameters were noted and that those parameters remained within safe bounds. 5.0 Additional Corrective Actions The unit was placed in the cold shutdown condition and the stem of the hot leg loop stop valve was replaced.
NAC FOAM 366A (9-83)
The stems of the other five Unit 1 loop stop *valves were ultrasonically tested and found to be satisfactory.
Technicians readjusted the intermediate range compensating voltage. 6. O Actions Ta-ken to Prevent Recurrence A detailed metallurgical analysis is being performed to determine exact cause of the valve stem failure. To reduce the stress on the valve stem, the operating procedure is being revised to normally operate the valves off the backseat.  


===7.0 Similar===
POW 28-06-01 NRC Form 366A.                                                                                                            U.S. NUCLEAR REGULATORY COMMISSION (9-831 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION                                    APPROVED 0MB NO. 3150-0104 EXPIRES: 8/31 /88 FACILITY NAME (1)                                                              Dq<:KET NUMBER (2)                                                  PAGE (3)
Events A similar failure occurred on the Unit 1 "B" loop Hot Leg Isolation Valve on December 1, 1973. 8.0 Manufacturer/Model Number Anchor Darling/Drawing nos. 95-11778 and 95-11779.
LER NUMBER (6)
* June 12, 1987 U.S. Nuclear Regulatory Commission Document Control Desk Oi6 Phillips Building Washington, D.C. 20555 Gentlemen:
YEAR :::::::::: SEQUENTIAL ::::::::::: REVISION
e VIRGINIA ELECTRIC AND POWER COMPANY Surry Power Station P. 0. Box 315 Surry, Virginia 23883 Serial No.: Docket No.: Licensee No.: 87-013 50-280 DPR-32 Pursuant to Surry Power Station Technical Specifications, Virginia Electric and Power Company hereby submits the following Licensee Event Report for Surry Unit 1. REPORT NUMBER 87-011-00 This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be reviewed by Safety Evaluation and Control. Very truly yours, R. F. Saunders Station Manager Enclosure cc: Dr. J. Nelson Grace Regional Administrator Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323 _._J}}
::::::::::  NUMBER    :::::::::: NUMBER Surry Power Station, Unit 1                                            0 1s101010121a10 817 -01111-olo oh &deg;Fo 1~
TEXT /ff more /J/NJCl1 is n,quired, U/ltl 11dditionsl NRC Form 3lil!iA '*) (17) 4.0              Inunediate Corrective Action The Operators performed all appropriate emergency procedures and function restoration procedures to ensure the plant was returned to a stable condition. This included manually reinstating the source range channels.
Also, the STA performed the critical safety function status tree review to ensure specific plant parameters were noted and that those parameters remained within safe bounds.
5.0              Additional Corrective Actions The unit was placed in the cold shutdown condition and the stem of the hot leg loop stop valve was replaced. The stems of the other five Unit 1 loop stop
                                                  *valves were ultrasonically tested and found to be satisfactory.
Technicians readjusted the intermediate range compensating voltage.
: 6. O            Actions Ta-ken to Prevent Recurrence A detailed metallurgical analysis is being performed to determine exact cause of the valve stem failure.
To reduce the stress on the valve stem, the operating procedure is being revised to normally operate the valves off the backseat.
7.0             Similar Events A similar failure occurred on the Unit 1 "B" loop Hot Leg Isolation Valve on December 1, 1973.
8.0             Manufacturer/Model Number Anchor Darling/Drawing nos. 95-11778 and 95-11779.
NRC FORM 366A (9-83)
* e VIRGINIA ELECTRIC AND POWER COMPANY Surry Power Station P. 0. Box 315 Surry, Virginia 23883 June 12, 1987 U.S. Nuclear Regulatory Commission                    Serial No.:         87-013 Document Control Desk                                  Docket No.:         50-280 Oi6 Phillips Building                              Licensee No.:           DPR-32 Washington, D.C. 20555 Gentlemen:
Pursuant to Surry Power Station Technical Specifications, Virginia Electric and Power Company hereby submits the following Licensee Event Report for Surry Unit 1.
REPORT NUMBER 87-011-00 This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be reviewed by Safety Evaluation and Control.
Very truly yours, R. F. Saunders Station Manager Enclosure cc: Dr. J. Nelson Grace Regional Administrator Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323
_._J}}

Latest revision as of 04:39, 23 February 2020

LER 87-011-00:on 870516,low Flow Reactor Trip Occurred. Caused by Hot Leg Loop Stop Valve Stem Failure Permitting Disc to Drop,Blocking Loop Flow.Procedure Revised to Reduce Stress on Valve stem.W/870612 Ltr
ML18150A171
Person / Time
Site: Surry Dominion icon.png
Issue date: 06/12/1987
From: Saunders R
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
87-013, 87-13, LER-87-011-01, LER-87-11-1, NUDOCS 8706230353
Download: ML18150A171 (4)


Text

POW 28-06-01 U.S. NUCLEAR REGULATORY COMMISSION NIIC Form 391}

19-83) APPROVED OMII NO. 3150-0104 EXPIRES: 8/31185 LICENSEE EVENT REPORT (LER)

FACILITY NAME 11) IoDOCKET NUMBER 121 I 5 I o I o I o I 2 I R In I

1 OF PAG~ 131 nI -:i Surrv Power Station. Unit 1 TITLE 1'1 Reactor Trip on Low RCS. Flow Due to Failure of Loop Stop Valve.

EVENT DATE 16) LER NUMBER 161 REPORT DATE 171 OTHER FACILITIES INVOLVED (Ill DOCKET NUMBERISl MONTH* DAY YEAR YEAR /{ SEQUENTIAL NUMBER () REVSSION NUMBER MONTH DAY YEAR FACILITY NAMES 01s1010101 I I o Is , I 6 8 7 011

- ol ,1 , - o I o ol6 112 sl1 0151010101 I I THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Ch.c:k on, or mor, of th1 following) (111 OPERATING MODE (II)

N 20.402(bl 20.40ll(cl X II0.73(o)(21Civl 73.7,Cbl I-POWER LEVEL 20.406(0)(1 )Ii) II0.31Cc)l11

-- II0.73(o)(2llvl 73.7,Ccl OTHER (S~ify in Abstr,ct (10) 0 I0 20.406(0)(1 )(Iii 60.311(c) 121 60.73(oll211vlll b1tow ,nd in Text. NRC Form 1*.*.*.*

20.40llloll1 )(Ill) 50.73(01121111

- II0.7311112llwiiillAI 366A) 20.40ll(o)(1 lflvl 20.40llloll1 llvl li0.73(111211ill

&0.73(oll2lliiil

- II0.731oll211wlllllBI 60.73(oll211xl LICENSEE CONTACT FOR THIS LER (121 NAME TELEPHONE NUMBER AREA CODE R. F. Saunders, Station Manager 0 1 o, q 3 I 51 7 I - 13 I 1 I 8 14 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (131 REPORTABLE .;.;;.;. .*.**.;. ;,;.;.*.* ;.*..*.* MANUFAC-MANUFAC-

.*.**.*. .*.*,*.*. *.*.:*.* SYSTEM COMPONENT CAUSE SYSTEM COMPONENT TURER TO NPRDS CAUSE TURER R ~~o~;:~iE ':J::1111:1::11:1:11111:1::1111:J:f i!iiliil!i:iiiji

  • =*=**=- :-:**.*. .....*.*.* *:*::*:

y .....,.; ;.;.,;.; ......,.;..,.,*.*. ,* *:*: .;.; .;.

X AIB I 1S1V I A1319 11 I I I I I I I I I I I I I ..

,;,;*.;.*.*. I I I I I I I  ;.-.
*:**:*: .... .*:*.*:*: :,:-:-:,:

SUPPLEMENTAL REPORT EXPECTED 114) MONTH DAY YEAR EXPECTED lxl YES (If yos, compl*r* EXPECTED SUBMISSION DATE/

ABSTRACT (Limit to 1400 SPIJCSs. i,tJ,, *PfJroxim,ttJly fifts6n singts-spacs typswrirrsn lim,s} (16) h NO SUBMISSION DATE 1151 018 310 817 On May 16, 1987 at 0824 hours0.00954 days <br />0.229 hours <br />0.00136 weeks <br />3.13532e-4 months <br />, with Unit 1 at 100% power, a low flow reactor trip occurred when "A"loop reactor coolant system (RCS) {EI IS-AB} flow decreased to 47%. Following the reactor trip, the source range channels {EIIS-DET} did not automatically reinstate. All other protection and control systems functioned properly. Operators followed appropriate plant procedures and stabilized the plant following the reactor trip.

This event occurred when the. II A" hot leg loop stop valve (EIIS-ISV} stem failed, permitting the disc to drop, partially blocking loop flow. A detailed metallurgical analysis is being performed to determine the failure mode and mechanism of the valve stem. The preliminary report indicates that failure was due to stress or fatigue. To reduce the stress on the valve stem, the operating procedure is being revised to normally operate the valves*off the backseat. The failure of source range channels to reinstate was due to the under compensation of the intermediate range channel NI-36. The source range channels were manually reinstated, and technicians readjusted the intermediate range compensating voltage.

8706230353 870612 Itl'-

PDR ADOCK 05000280 \ (\

s PDR NRC Form 386 19-83)

POW 28-06-01 NRC l'orm 366A

  • U.S. NUCLEAR REGULATORY COMMISSION (9-83)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVED 0MB NO. 3150--0104 EXPIRES: 8/31/88 FACILITY NAME (1) DOCKET NUMBER (2) PAGE (3)

LER NUMBER (6)

YEAR  :::::::::: SEQUENTIAL ::::::::::* REVISION

  • NUMBER .'."."."." NUMBER Surry Power Station, Unit 1 o 1s Io Io Io I 2 I 81 O 81 7 - 011 I1 - 0 I O Ol 2 OF OI 3 TEXT '" more IP"C9 i& "'flUired, U&tl *dditiona/ NRC Form 36flA '&/ (17) 1.0 Description of the Event On May 16, 1987 at 0824 hours0.00954 days <br />0.229 hours <br />0.00136 weeks <br />3.13532e-4 months <br />, with Unit 1 at 100% power, a low flow reactor trip occurred when "A" loop reactor coolant system {EIIS-AB} (RCS) flow decreased to 47%. Following the reactor trip, the source range channels {EIIS-DET} did not automatically reinstate.

All other protection and control systems functioned properly. Operators followed appropriate plant procedures and stabilized the plant following the reactor trip.

2.0 Safety Consequences and Implications The low flow reactor trip automatically trips the reactor to maintain sufficient margin above a DNBR of 1.3 with a loss of RCS flow. The complete loss of flow in one loop from a reactor power of 100% (2441 MWt) with three loops operating is an analyzed event.

During the event, "A" loop flow was maintained at approximately 47% and total core flow remained at 84%.

A confirmatory analysis performed by Nuclear Engineering concluded that DNBR was maintained above the accident analysis value of 1.3. In addition, all other safety related systems remained operable during the event, and plant parameters remained well within the bounds of the accident analysis. Therefore this event did not constitute *an unreviewed safety ques*tion and the health and safety of the public were not affected.

3.0 Cause The cause of this event was a failure of the "A" RCS hot leg loop stop valve (MOV-1590) {EIIS-ISV}. The valve stern failed, permitting the disc to drop, partially blocking the loop flow.

The valve stern is being analyzed for failure mode and mechanism. A supplemental LER will be submitted when this analysis is completed. The preliminary report indicates that failure was due to fatigue or stress.

The failure of the source range channels to reinstate was due to the under compensation of the intermediate range channel NI-36.

NAC FOAM 366A (9-83)

POW 28-06-01 NRC Form 366A. U.S. NUCLEAR REGULATORY COMMISSION (9-831 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVED 0MB NO. 3150-0104 EXPIRES: 8/31 /88 FACILITY NAME (1) Dq<:KET NUMBER (2) PAGE (3)

LER NUMBER (6)

YEAR :::::::::: SEQUENTIAL ::::::::::: REVISION

NUMBER  :::::::::: NUMBER Surry Power Station, Unit 1 0 1s101010121a10 817 -01111-olo oh °Fo 1~

TEXT /ff more /J/NJCl1 is n,quired, U/ltl 11dditionsl NRC Form 3lil!iA '*) (17) 4.0 Inunediate Corrective Action The Operators performed all appropriate emergency procedures and function restoration procedures to ensure the plant was returned to a stable condition. This included manually reinstating the source range channels.

Also, the STA performed the critical safety function status tree review to ensure specific plant parameters were noted and that those parameters remained within safe bounds.

5.0 Additional Corrective Actions The unit was placed in the cold shutdown condition and the stem of the hot leg loop stop valve was replaced. The stems of the other five Unit 1 loop stop

  • valves were ultrasonically tested and found to be satisfactory.

Technicians readjusted the intermediate range compensating voltage.

6. O Actions Ta-ken to Prevent Recurrence A detailed metallurgical analysis is being performed to determine exact cause of the valve stem failure.

To reduce the stress on the valve stem, the operating procedure is being revised to normally operate the valves off the backseat.

7.0 Similar Events A similar failure occurred on the Unit 1 "B" loop Hot Leg Isolation Valve on December 1, 1973.

8.0 Manufacturer/Model Number Anchor Darling/Drawing nos. 95-11778 and 95-11779.

NRC FORM 366A (9-83)

  • e VIRGINIA ELECTRIC AND POWER COMPANY Surry Power Station P. 0. Box 315 Surry, Virginia 23883 June 12, 1987 U.S. Nuclear Regulatory Commission Serial No.: 87-013 Document Control Desk Docket No.: 50-280 Oi6 Phillips Building Licensee No.: DPR-32 Washington, D.C. 20555 Gentlemen:

Pursuant to Surry Power Station Technical Specifications, Virginia Electric and Power Company hereby submits the following Licensee Event Report for Surry Unit 1.

REPORT NUMBER 87-011-00 This report has been reviewed by the Station Nuclear Safety and Operating Committee and will be reviewed by Safety Evaluation and Control.

Very truly yours, R. F. Saunders Station Manager Enclosure cc: Dr. J. Nelson Grace Regional Administrator Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323

_._J