05000446/LER-1996-001, :on 960107,allowed Outage Time Was Exceeded in Conjunction W/Enforcement Discretion for RCS Instrument Channel.Caused by Action Statement Requirements Not Being Met
| ML20097A159 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 01/29/1996 |
| From: | Kross D, Terry C TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LER-96-001, LER-96-1, TXX-96032, NUDOCS 9602050192 | |
| Download: ML20097A159 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(1) 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4461996001R00 - NRC Website | |
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C File # 10200 Ref. # 10CFR50.73(a)(2)(1)
TUELECTRIC C. Lance Terry Group Yko Prendent January 29, 1996 U. S. Nuclear Regulatory Commission s
Attn: Document Control Desk Washington, DC 20555 SUBJECT: COMANCHE PEAX STEAM ELECTRIC STATION (CPSES) UNIT 2 DOCKET NOS. 50 446 CONDITIONS PR0HIBITED BY TECHNICAL SPECIFICATIONS LICENSEE EVENT REPORT 446/96 001 00 REF: 1) TU Electric letter logged TXX 96009 from C. L. Terry to the NRC dated January 4, 1996
- 2) TV Electric Letter logged TXX-96010 from Mr. C. L. Terry to the NRC dated January 5, 1996 requesting enforcement discretion for wide range RCS temperature T n remote shutdown indication for one RCS loop
- 3) NRC letter dated January 11, 1996 from Mr. W. D. Beckner to Mr. C. L. Terry granting enforcement discretion (NOED No.
96-6 001)
- 4) NRC Inspection Manual. Part 9900, " Operations - Enforcement Discretion," dated November 2, 1995 Gentlemen:
Enclosed is Licensee Event Report (LER) 96 001 00 for Comanche Peak Steam Electric Station Unit 2. " Allowed Outage Time Exceeded in Conjunction With Enforcement Discretion For The Reactor Coolant System Instrument Channel."
Via Reference 1 and Reference 2. TU Electric requested enforcement discretion not to enforce the shutdown requirement following the 7 day Allowed Outage Time (A0T) for the failed Wide Range RC3 Te.np. T n Remote Shutdown Indication instrument channel for RCS Loop 1.
The enforcement discretion was granted via reference 3.
9602050192 960129 PDR ADOCK 05000446 S
--w-l P.O. Box 1002 Olen Rose. Texas 76043 n
The subject Licensee Event Repoit is being submitted to satisfy the requirements of 10CFR50.73(a)(2)(1)(B) and Reference 4, because the time requirements for the action statement were not met (see Reference 1 and Reference 2).
Sincerely, n
C. L. Terry I
OB:ob Enclosures cc:
Mr. L. J. Callan, Region IV Mr. W. D. Johnson, Region IV Resident Inspectors, CPSES A
Enclosur3 to TXX-96032
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Facity Name (1)
Docket Number (2)
Page (3)
COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 05000446 1
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j hIlhED OUTAGE TIME EXCEEDED IN CONJUNCTION WITH ENFORCEMENT DISCRETION FOR THE REACTOR COOLA i.
SYSTEM INSTRUMENT CHANNEL Evert Date ((5)
LER Number (6)
Report Dale (7)
Other FacNees Irwolved (5) n~
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DATE (15)
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ABSTRACT (Limit to 1400 spaces, I s., approximately 15 single-spaced typewritten lires) (16)
On December 31, 1995, at approximately 2:10 a.m. the Wide Range Reactor Coolant l
System (RCS) Temp. Tn for one RCS Loop was discovered to be inoperable.
Troubles %oting efforts indicated a ground. Location of the ground was isolated to t
an area !nside containment that is normally only accessible during periods of a j
reactor shutdown. Radiation levels, temperature and personnel safety considerations preclude l'urther trouble shooting and corrective actions without performing a plant shutdown and a possible cooldown. The subject Licensee Event Report is being i
submitted to satisfy the requirements of 10CFR50.73(a)(2)(1)(B), because the time i
requirements for the action statement were not met. TV Electrit: requested enforcement discretion not to enforce the shutdown requirement following the 7 day Allowed Outage Time (A0T) for the failed Wide Range RCS Temp.-T n Remote Shutdown
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Indication instrument channel for RCS Loop 1.
The enforcement discretion was granted. CPSES Unit 2 has no other outages planned during the 7 weeks prior to the i
scheduled start of the refueling outage on February 22,19%.
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Enc 19sure to TXX-96032 SlHiARY OF THE EVENT, INCLUDING DATES AND APPR0XIMATE TIMES On December 31, 1995, at approximately 2:10 a.m. the Wide Range RCS Temp. Tn for one RCS Loop was discovered to be inoperable.
Troubleshooting efforts indicated a ground. Location of the ground has been isolated to an area inside containment that is normally only accessible during periods of a reactor shutdown. Radiation levels, temperature and personnel safety considerations preclude further trouble shooting and corrective actions without performing a plant shutdown and a possible cooldown.
CPSES Unit 2 is scheduled to commence a refueling outage on February 22, 1996. CPSES Unit 2 has no other outages planned during the 7 weeks prior to the scheduled start of the refueling outage.
1 On January 5, 1996 at approximately 3:00 p.m. (CDT) during a j
teleconference with the NRC, TU Electric requested was granted a Notice of Enforcement Discretion (N0ED). The N0ED was requested to allow CPSES Unit 2 to continue to operate with the normal Wide Range RCS 4
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Enclosura to TXX-96032 NRC FC.M 366A U S NUCLEAR F.EGULATORY COMMISSION i
(4 05)'
LICENSEE EVENT REPORT (LER) l TEXT CONTINUATION Fecay Name (1)
W Year R
I COMANCilE PEAK STEAM ELEC1RIC STATION UNIT 2 05000446 9
6 0
0 1
0 0
3 6
OF Text (imore space is required, use adeuonal copes of NRC Form 366A) (17) 1 l
l (Reactor Coolant System) Temp.(Temperature) T n Remote Shutdown Indication for 1 of 4 loops inoperable. An exigent change to the 1
Technical Specifications to temporarily remove the requirement for the l
inoperable Tn instrument was submitted on January 5,1996. Without the requested enforcement discretion and the requested Technical Specification change, compliance with CPSES Technical Specification 3.3.3.2.1 would require that TV Electric initiate unnecessary mode changes without a corresponding safety benefit, thus resulting in an
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i unnecessary plant transient and unnecessary system realignments.
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i E.
THE HETH00 0F DISCOVERY OF EACH COMP 0NENT OR SYSTEM FAILURE OR i
PROCEDURAL ERROR l-The Inoperability of the T n instrument was discovered during a routine surveillance, TV Electric management recognized that the additional time required to 5
allow Unit 2 to operate until the scheduled refueling outage would exceed the required action statement.
II.
ANALYSIS OF THE EVENT
A.
SAFETY SYSTEM RESPONSES THAT OCCURRED Not applicable No Safety System responses occurred. The subject Licensee Event Report is being submitted to satisfy the requirements of j
10CFR50.73(a)(2)(1)(B) and NRC Inspection Manual Part 9900 "10 CFR Guidance", because the time requirements for the action statement were not n:ct.
B.
DURATION OF SAFETY SYSTEM TRAIN INOPERABILITY Not Applicable No safety system trains were inoperable during this event.
l Englosure to TXX-96032 us.wuct Anneoutucwecommssion ma reausee4, LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION I
Facety Name(1)
Docket g
COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 05000446 9
6 0
1 0
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OF akt more space is requred, use additories ccpsee of NRC Form 366A) (17)
C.
SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT The subject instrument is part of the CPSES design for shutdown from outside the control room (see CPSES Final Safety Analysis Report (FSAR) section 7.4.1.3).
The Hot Shutdown Panel (HSP) and the Shutdown i
Transfer Panel (STP) are provided as part of the CPSES unit design for shutdown outside the control room. Wide Range RCS Temperature indications are provided on the HSP for the RCS Loops. RCS temperature is used for monitoring the cooldown of the RCS and for the switch over to Residual Heat Removal (RHR). In the unlikely event that shutdown from outside the control room (during the duration of the enforcement discretion) is required, the inoperability of Wide Range Temp. T n for a single RCS Loop is expected to have no measurable impact on the ability of the operators to safely cooldown the RCS and switch over to RHR.
The Tn indication is used for monitoring natural circulation cooldown.
Steam Generator Pressure is the primary means of temperature control based on the saturated steam conditions in the Steam Generator. Under low steam flow conditions, the Steam Generator saturation temperature closely approximates cold leg temperature. Knowledge of the 7
saturation temperature corresponding to the observed steam pressure provides the best indicator of RCS conditions. T, and Tn indications i
lag behind the steam pressure indication, particularly under natural circulation conditions due to the loop transit time. For this reason, the Tn indication is a secondary indication to Steam Generator pressure.
For the situation of cooldown when there is forced RCS flow, there is a small differential temperature across the Steam Generator and T, is nearly the same as the T, and provides the same information as the inoperable Tn. For the situation of natural circulation, there is a larger differential temperature. However, the T n of the loop without indication is approximately the same as that indicated in the other active loop with Tn indication. Abnormal operating procedures for shutdown from outside the Control Room address the use of Steam Pressure as the primary indicator of RCS temperature for comparison to the RCS Pressure (also available on the HSP) to confirm adequate subcooling margin exists during the cooldown. The procedure specifically calls for the use of steam generator pressure in the
Encipsura to TXX-96032 jU 8 NUCLEAR f.EGULATORY COMMISSION (446i l
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION Facesy Narne (1)
Dociet z
y M
u-a.._m COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 05000446 9
6 0
0 1
0 0
5 6
Test (i more space a requred, use addnional capise of NRC Form 308A) (17) i determination of subcooling margin, cooldown rate and RCS temperature.
The operators are trained on these procedures and also to use all available instrumentation. With the operator training being refreshed, j
and the recently confirmed operability of the other remote shutdown
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indications, one Tn indication in an active loop provides sufficient confirmation for the operator to perform a controlled cooldown of the j
The worst case scenario for shutdown from outside the control room is i
for those instances involving,a fire in either the control room or the cable spreading room. The failed T n indication is one of two which have l
been analyzed to remain available for operation at the HSP following a
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fire per the Fire Safe Shutdown Analysis. Only two have been analyzed, as only those Steam Generators fed by the Train A Auxiliary Feedwater i
Pump are used for plant cooldown following a postulated fire. If this event were to occur, the operator would retain indication of RCS hot leg temperature from the remaining T n indication and use the
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correlations previously stated. For shutdowns other than post fire l
shutdown, the remaining Tn indicators (3) allow for plant cooldown.
1 Therefore loss of a single loop T n indicator should have minimal safety I
significance with no potential for negative consequences should use of j
the HSP be required.
III.
CAUSE OF THE EVENT
i Limiting Condition for Operation (LCO) 3.3.3.2.1, "R' mote Shutdown Instrumentation," requires, in part, that one Wide Range RCS Temp. T n per RCS Loop be OPERABLE in MODES 1, 2, and 3. ACTION Statement "a" requires that an inoperable instrument be restored to OPERABLE status within 7 days or be in at least MODE 4, HOT SHUTDOWN, within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
This event was considered reportable because the time requirement for the action statement was not met, An N0ED was requested and received before a violation of the Technical Specification occurred.
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Enc!osura to TXX-96032 NRC FeRM 366A U 8. NUCLEAR 7.EGULI, TORY COMMISSON
'p.95f LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION (8
Fac4ky Name (1)
Docket g_
COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 05000446 9
6 0
0 1
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6 Text W more space a rowed, use addeorW copies of NRC Form 366A) (IT)
IV.
CORRECTIVE ACTIONS
On January 5, 1996, prior to exceeding the allowed outage time, it was recognized by TU Electric management that the additional time would be required to allow Unit 2 to operate until the scheduled refueling outage would exceed the required action statement. TU Electric believes that the required actions taken to acquire the NOED and Technical Specification change are sufficient until corrective actions to repair the inoperable T n instrument during the upcoming Unit 2 refueling outage. Therefore, no further actions are warranted.
V.
PREVIOUS SIMILAR EVENTS
There have been other previous events which resulted in exceeding Technical Specification action statements (refer to LER 445/95 001 00 and LER 445/95-004-00). However, the causes for the aforementioned events were significantly different than the subject event. Corrective actions taken to resolve the root causes of the previous events would not have prevented this event,