ML18009A855
| ML18009A855 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 04/03/1991 |
| From: | Richey R CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CON-NRC-749 HO-910034-(O), NUDOCS 9104080161 | |
| Download: ML18009A855 (10) | |
Text
ACCELERATED DISTRIBUTION DEMONSTRATION SYSTEM
'EGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
CESSION NBR:9104080161 DOC.DATE: 91/04/03 NOTARIZED: NO
'CIL:50-400 Shearon Harris Nuclear Power Plant, Unit 1, Carolina AUTH.NAME AUTHOR AFFILIATION RICHEY,R.B.
Carolina Power
& Light Co.
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
DOCKET 05000400 D
v
/
05000400 A
SUBJECT:
Responds to NRC 910403 ltr re violations noted in insp rept 50-400/91-01.Corrective actions:procedures have been revised require draining of RVLIS reactor head sensor
& plant procedures revised to require filling of reference leg.
DISTRXBUTION CODE:
IE01D COPIES RECEIVED:LTR J
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TITLE: General (50 Dkt)-Insp Rept/Notice of Vi&o ation Response NOTES:Application for permit renewal filed.
RECIPIENT ID CODE/NAME PD2-1 PD INTERNAL: ACRS AEOD/DEIIB DEDRO NRR SHANKMAN,S NRR/DOEA/OEAB NRR/DRIS/DIR NRR/PMAS/ILRB12 OE~L 02 EXTERNAL EG&G/BRYCEiJ H
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1 RECIPIENT ID CODE/NAME BECKER,D AEOD AEOD/TPAB NRR MORXSSEAU,D NRR/DLPQ/LPEB10 NRR/DREP/PEPB9D NRR/DST/DIR 8E2 NUDOCS-ABSTRACT OGC/HDS1 RGN2 FILE 01 NRC PDR COPIES LTTR ENCL 1
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A NOTE TO ALL"RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAMEFROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
OTAL NUMBER OF COPIES REQUIRED:
LTTR 24 ENCL 24 D
Carolina Power & Light Company P.O. Box 165 ~ New Hill,N.C. 27562 R. B. RICHEY Vice President Harris Nuclear Project HARRIS NUCLEAR PROJECT P.O.
Box 165 New Hill, North Carolina 27562 APR
- 3 1991 Letter Number.'HO-910034 (0)
Document Control Desk United States Nuclear Regulatory Commission Washington, DC 20555 NRC"749 SHEARON HARRIS NUCLEAR POWER PLANT DOCKET NO. 50-400 LICENSE NO. NPF-63 REPLY TO A NOTICE OF VIOLATION Gentlemen:
In reference to
'your letter of'arch 4,
- 1991, referring to I.ED Report RII:
50-400/91-01, the attached is Carolina Power and Light Company's reply to the violation identified in Enclosure 1.
It is considered that the corrective actions taken/planned are satisfactory for resolution of the item.
Thank you for your consideration in this matter.
Very truly yours, R. B. Richey Vice President Harris Nuclear Project MGW:kjc Attachment cc'.
Mr. R. A. Becker (NRC)
Mr. S.
D. Ebneter (NRC - RII)
Mr. J.
E. Tedrow (NRC - SHNPP)
~104080161 910403 POD ADOCK 0 000400 9
'DR MEM/HO-9100340/1/OS1
/(0
0 0
Attachment to CP&L Letter of Res onse to NRC I.E.
Re ort RII:
50-400 91-01 Violation Re orted Violation.'echnical Specification 6.8.1.a requires that written procedures be established and implemented covering procedures outlined in Appendix A of Regulatory Guide 1.33, Revision 2, February 1978.
Regulatory Guide 1.33, Appendix A, Paragraph 10, requires that written procedures be provided for draining the Reactor Coolant System.
Operations Procedure OP-ill, Rev. 4, Residual Heat Removal
- System, Section 8.1, Mid Loop Operation of the Reactor Coolant
- System, Step 8.1.1.3 requires that one train of Reactor Vessel Level Instrumentation System indication be operational as an initial condition for performance of this evolution.
Contrary to the
- above, on November 14,
- 1990, no channels of the Reactor Vessel Level Instrumentation System were operational because the licensee failed to fill a common Reactor Vessel Level Instrumentation System reference leg.
This resulted in instrument inaccuracies which exceeded the RVLIS design accuracy.
This a Severity Level IV violation (Supplement I).
Denial or Admission and Reason for Violation'.
The violation is admitted.
Prior to this event CP&L did not recognize the need to fill the Reactor Vessel Level Instrumentation System (RVLIS) reference leg.
Prior to commencing draindown of the Reactor Coolant System (RCS),
procedural prerequisites for entering reduced RCS inventory were satisfied.
During initial draining of the reactor vessel to mid loop on November 11,
- 1990, the RVLIS indication was detected to be approximately 19 inches higher than expected when compared to the standpipe reading.
Both trains of RVLIS displayed the same offset.
This offset was investigated and actions were taken to resolve discrepancies prior to mid loop operations.
Specifically, a
new curve of RVLIS versus standpipe level indication was provided to monitor level during mid loop operations.
Reactor vessel level tracked as expected along this revised curve as the level was lowered to mid loop.
During subsequent changes in reactor vessel
- level, standpipe and RVLIS indications began to deviate from expected correlation due to head venting problems.
- However, the RVLIS indications were proven to be correct for-the revised curve when a proper head vent was obtained.
Therefore, at least one train of RVLIS remained in operation during mid loop conditions.
MEM/HO-9100340/2/OS1
Denial or Admission and Reason for Violation'(continued)
Although not cited in the Notice of Violation, the inspection report stated that the failure to fill the reference leg resulted in unacceptable'onsequences with respect to 'he emergency response guidelines.
The vendor (Westinghouse) had previously stated that the RVLIS inaccuracies would not be a
concern since RVLIS is only used for trending purposes during a
large break LOCA.
CPGL provides the following additional response to these concerns:
Assuming the operator has stopped the reactor coolant pumps (RCPs) per the emergency procedures, the core cooling status tree actually considers two sets of sym'ptoms to determine a
red priority condition for core cooling:
1.
Core exit thermocouples (TCs) greater than 1200'F, or 2.
Core exit TCs greater than 730'F and RVLIS less than 39X.
If either of the above sets of symptoms is true, the operator is directed to FRP-C.l,
Response
to Inadequate Core Cooling (ICC).
In order of priority and occurrence, the operator would take the following major actions in FRP-C.1 to mitigate the ICC condition.'stablish safety injection flow.
Rapidly depressurize the steam generators (SGs) to depressurize the RCS.
Restart RCPs and open reactor coolant system (RCS) vent paths to containment.
If only one (but not both) of the symptoms in 2 above is true, the operator is directed to FRP-C.2,
Response
to Degraded Core Cooling.
This would be considered a slightly less severe or magenta priority condition for core cooling.
In FRP-C.2, the operator would take the following major actions.
Establish safety injection flow.
Initiate a
controlled SG depressurization to cooldown and depressurize the RCS.
It should be noted that for a large LOCA, the event for which the RVLIS accuracy is in question, the only meaningful actions in FRP-C.1 and FRP-C.2 that'he operator could take would be to establish SI flow.
The break itself would cause the RCS to depressurize.
The operator would also have been required to MEM/HO-9100340/3/OS1
0
Denial. or Admission and Reason for Violation: (continued) verify or establish SI flow previously in Path 1.
- Thus, the transition to FRP-C.1 and/or FRP-C.2 would merely be made as a
backup to Path 1.
Therefore,. it is appropriate that RVLIS only be used for trending purposes for a large break LOCA.
For small LOCAs (i.e.,
break sizes of roughly 4"
diameter or smaller),
the RVLIS accuracy is expected to be within 6X.
With this accuracy, the emergency procedures would direct the operator t'o take proper actions when required and not to take the more extreme actions in FRP-C.1 when it would not be appropriate.
Corrective Ste s Taken and Results Achieved:
Two reasons were identified to cause the errors in RVLIS indication.'Failure to properly fill the head sensor reference leg and failure of the head vent system to vent the reactor vessel head as the water level was lowered.
Failure of the head vent system created a
vacuum in the reactor vessel head and caused noncondensible gases in the RVLIS reference leg to come out of solution.
The noncondensible gases were present because the reference leg had not been backfilled during the reactor fill and vent procedure.
These gases displaced water from the reference leg, resulting in a higher RVLIS indication.
These problems were identified prior to the reactor vessel being in a
mid loop condition.
A temporary curve was provided to Operations personnel with the expected RVLIS indication versus standpipe level.
The reactor head was vented through the RVLIS refueling connection at approximately 1700 on November 17, 1990.
Initial assumptions for actual water level in the reEerence leg were confirmed correct (i.e.,
RVLIS level changed by the expected amount).
Corrective Ste s Taken to Avoid Further Violations:
Procedures have been revised to require draining of the RVLIS
, reactor head sensor when it is disconnected for head removal prior to entering mid loop operations.
This ensures that the actual water volume in the reference leg will be known and can be accounted for during future mid loop operations.
Plant procedures are being revised to require filling of the reference leg during the reactor filland vent procedure.
A positive vent that bypasses the restriction orifice in the head vent is being installed during the current refueling outage.
This modification will provide for proper venting during subsequent reactor vent operations.
MEM/HO-9100340/4/OS1
Date When Full Com liance Mill Be Achieved:
The actions stated above will be completed during the current refueling outage prior to the reactor fill and vent procedure in preparation for reactor startup.
The projected date for this is May 7, 1991.
MEM/HO-9100340/5/OSl
A~