05000456/LER-2002-003, Isolated Loop Reactor Coolant System Boron Sample Outside of Technical Specification Frequency Requirement Due to Misapplication of the Implementing Procedure

Isolated Loop Reactor Coolant System Boron Sample Outside of Technical Specification Frequency Requirement Due to Misapplication of the Implementing Procedure

ML023230311
Person / Time
Site:	Braidwood
Issue date:	11/12/2002
From:	Vonsuskil J Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BW02118 LER 02-003-00
Download: ML023230311 (6)

LER-2002-003, Isolated Loop Reactor Coolant System Boron Sample Outside of Technical Specification Frequency Requirement Due to Misapplication of the Implementing Procedure

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
4562002003R00 - NRC Website

text

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Exelon Generation Company, LLC Braidwood Station 35100 South Rt 53, Suite 84 Braceville, IL 60407-9619 Tel 815-458-2801 www exeloncorp corn Nuclear November 12, 2002 BW020118 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457

Subject:

Submittal of Licensee Event Report Number 2002-003-00, Isolated Loop Reactor Coolant System Boron Sample Outside of Technical Specification Frequency Requirement Due to Misapplication of the Implementing Procedure The enclosed Licensee Event Report (LER) is being submitted in accordance with 10 CFR 50.73, "Licensee event report system", paragraph (a)(2)(i)(B). 10 CFR 50.73(a) requires an LER to be submitted within 60 days after discovery of the event; therefore, this report is being submitted by November 12, 2002.

Should you have any questions concerning this letter, please contact Amy Ferko, Regulatory Assurance Manager, at (815) 417-2699.

Respectfully, ate Vice President Braidwood Station

Enclosure:

LER Number 2002-003-00 cc:

Regional Administrator - Region IlIl NRC Braidwood Senior Resident Inspector 9

BwAP 1 205-3T1 Revision 8 BRAIDWOOD INDEPENDENT TECHNICAL REVIEW FORM ITR Number:

°>2 °Y/

Date:

Subject Review:

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Requested by:

(Print)

Extension:

2 J

Disciplines Required:

N' NPPT 9 RO El RE [II CH El RP El l&C El M&ES Nuclear Power Plant Technology Reactor Operations Reactor Engineering Chemistry Radiation Protection Instrumentation and Control Mechanical and Electrical Systems Is PORC also required?

O-YES (ITR Approval by Station Manager)

4 NO ITR Participants

OPS s-]

ITR Approval Position:

R4m ITR Membership Assigned by:

Systems Engineering Supervisor

/(- ; 2-I Date I

10CFR50.59 Screening is Required:

17 YES If yes, attach completed documentation.

r0NO I 10CFR50.59 Evaluation is Required:

If yes, attach completed documentation.

Findings and Recommendations:

RecC i'e7Alf c

Jtv E YES

' 7/ r4c tZE ZoK ITR Review Committee:

I Signature indicates concurrence with Findings and Recommendations including 10CFR50 59 Screening or Evaluation, if one was performed.

Discipline(s)

Date Pr

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_/70 I

/0^t it/ 1,)OZ_

PORC Approved on

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II____

Approved by:

Return original IT and a copy of Attachments to SED Clerk within 30 days.

ii 101.

(Final)

I

Abstract

Braidwood Station Technical Specification (TS) Surveillance Requirement (SR) 3.4.18.2 requires the isolated loop Reactor Coolant System (RCS) boron concentration to be verified to be greater than or equal to the required shutdown margin (SDM) boron concentration of the unisolated portion of the RCS within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> prior to unisolating the loop.

Braidwood has not always been in literal compliance with the SR time requirement.

During refueling outages, isolated loop boron concentration is determined from samples of the water used to fill the RCS loop.

However, these samples were often collected and analyzed greater than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> before the loop isolation valves were opened.

The root cause of the TS SR noncompliance was a misapplication of a note that was added to the procedure that directs RCS loop restoration (BwOP RC-8).

This procedure was relied upon as the implementing procedure to ensure the requirements of SR 3.4.18.2 were met.

The SR was interpreted, in the context of the note, as being met when the RCS loop fill boron concentration was compared to the required SDM boron concentration within the SR time requirements before unisolating the isolated loop.

The note was not properly reviewed in accordance with 10 CFR 50.59 to ensure literal compliance with the TS SR.

This event is applicable to both Braidwood Units.

This event is being reported pursuant to 10CFR50.73(a)(2)(i)(B).U.S. NUCLEAR REGULATORY COMILMISSION (1-200A)

LICENSEE EVENT REPORT (LER)

FACILITY NAMIE (1)

DOCKET (2)

LER NUMIBER (6 PAGE (3)

YEAR SEQUENTIALI REVISION Braidwood, Unit 1 STN 05000456 l 2 of 4 l

l 1

200 2 -

003 - 00 l

A.

Plant Operating Conditions Before The Event

Unit: 1 Event Date: 9/11/2002 Event Time: 1450 MODE: 1 Reactor Power: 100 percent Unit 1 Reactor Coolant System (RCS)(AB] Temperature: 586 degrees F Unit 1 RCS Pressure: 2235 psig Unit: 2 Event Date: 9/11/2002 Event Time: 1450 MODE: 1 Reactor Power: 100 percent Unit 2 Reactor Coolant System (RCS)[AB] Temperature: 580 degrees F Unit 2 RCS Pressure: 2225 psig Bo.

Description of Event

There were no structures, systems, or components inoperable at the start of the event that contributed to the event.

The surveillance requirement (SR) for verifying that the isolated loop boron concentration is greater than or equal to the required shutdown margin (SDM) boron concentration of the unisolated portion of the reactor coolant system (RCS) within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> prior to opening the hot or cold leg loop stop isolation valve (LSIV) in the isolated loop (SR 3.4.18.2) has not been complied with during refueling outages at Braidwood since approximately 1995.

A specific surveillance procedure has not existed to ensure the requirements of SR 3.4.18.2 are followed.

Instead, the operating procedure for restoring a RCS loop to service (BwOP RC-8, "Restoring a Reactor Coolant Loop to Service") has been relied upon as the implementing procedure to ensure compliance with SR 3.4.18.2.

The key procedure step (F.3) states, "Determine that the Boron Concentration in the Isolated RCS Loop is greater than or equal to the Required Shutdown Margin boron concentration of the unisolated portion of the RCS. (This must be determined within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> prior to opening the Loop Stop Valves.)" A note preceding this step states "Loop Boron Concentration can be inferred from samples of fill source during loop fill.

As long as no actions to dilute the isolated loop occur between loop fill and opening of stop valves, these results equate to Loop Boron Concentration."

This note was added to BwOP RC-8 in 1995.

Before the note was added to the procedure, the RCS loop boron concentration was controlled by a chemistry procedure and was required to be determined within the TS SR time requirement prior to opening the RCS loop isolation valves.

The RCS loop boron samples were locally obtained from a pressure tap on the loop flow transmitters.

The chemistry procedure was referenced in BwOP RC-8, but this reference was removed in the 1995 procedure revision.

The accompanying 10 CFR 50.59 screening for the procedure change determined that an evaluation in accordance with 10 CFR 50.59 was not required.

A Station On-Site Review (OSR) of the change and the accompanying note was not performed.

This note was essentially a TS interpretation inserted into the procedure.

A 10 CFR 50.59 evaluation and an OSR should have been performed for the TS interpretation to ensure the appropriate reviews were performed before implementing the change.

Station administrative procedures required a TS interpretation to have an Independent

NRC FORMI 366A U.S. NUCLEAR REGULATORY CONMMISSION (1-20W)

LICENSEE EVENT REPORT (LER)

FACILITY NAMIE (1)

.1 DOCKET (2)

LER NUMBER 6PAGE 3l YEAR SEQUENTIAL REVISION Braidwood, Unit 1 STN 05000456 l

l 3 of 4 2002 -

003 00 Technical Review, a Plant Operations Review Committee (PORC) review, NRC notification, and Station Manager approval.

Operating procedure BwOP RC-8 was changed for several reasons.

Since the loop could not be circulated to mix the contents of the loop, the sample results were not accurate or representative of actual boron concentration.

The time from when the sample was collected from the local RCS loop drain tap until it was analyzed often challenged the TS time requirement.

The sample had to be drawn locally from the isolated RCS loop, transported to the Chemistry lab, and then analyzed. A RCS sample also had to be collected and analyzed for boron concentration for comparison.

The boron concentration of the loop fill source was sampled during the loop fill to ensure the boron concentration was greater than or equal to the required SDM boron concentration.

The only other sources of water into the isolated RCS loop are RCS seat leakage past the LSIVs and RCP seal injection.

The boron concentration of both of these water sources is greater than or equal to the required SDM boron concentration. As long as no RCS dilutions had been performed since the RCS loop was filled, the valid conclusion is that the isolated RCS loop boron concentration is the same or greater than RCS loop fill boron concentration measured during the loop fill.

The common practice at Braidwood was to fill the isolated RCS loop and record the boron concentration of the fill source for each loop.

Before opening the RCS LSIVs, the boron concentration of the unisolated portion of the RCS was determined.

Within 30 minutes of opening the RCS LSIVs, the RCS loop temperatures were checked to be within the TS limit and the boron concentration of the unisolated portion of the RCS was compared to the fill source boron concentration.

If the temperatures and boron concentrations were within the TS limits, the RCS LSIVs were opened.

Comparing the fill source boron concentration to the TS required boron concentration within 30 minutes, regardless of when that boron concentration was actually determined, was believed to meet the TS SR time requirement.

C.

Cause of Event

The root cause of the TS SR noncompliance was the misapplication of a note that was added to the procedure that directs RCS loop restoration.

The note was not properly reviewed in accordance with 10 CFR 50.59 to ensure literal compliance with the TS SR.

This procedure was relied upon as the implementing procedure to ensure the requirements of SR 3.4.18.2 were met.

The sample frequency was interpreted, in the context of the note, as being met by comparing the RCS loop fill boron concentration to the required SDM boron concentration within the SR time requirements before opening the isolated loop isolation valves.

D.

Safety Consequences

The isolated RCS loops are filled with borated water of a known concentration.

The concentration is maintained greater than the required SDM boron concentration.

The only sources of water into the isolated RCS Loop are from the loop fill system, leakage past the LSIVs, and RCP seal injection.

Any leakage past the LSIVs would be the same concentration as the unisolated RCS system (i.e. greater than the required

NRC FORNI 366A U.S. NUCLEAR REGULATORY CONMIMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

FACILITY NAMIE DOCKET (2)

LER NUMIBER (6)

PAGE (3)

YEl SEQUENTIAL REVISION NUMBER NUMBER Braidwood, Unit 1 STN 05000456 l 4 of 4 2002 -

003 -

00 SDM boron concentration).

The RCP seal injection water boron concentration is the same as the RCS loop fill boron concentration or the unisolated RCS boron concentration.

Any dilution of the isolated loop would necessarily occur also in the unisolated RCS.

Since a RCS SDM boron concentration determination is required prior to opening the RCS LSIVs per BwOP RC-8, the potential to open the RCS LSIVs with diluted water from the isolated RCS loop is small.

The LSIVs have been opened several times without incident (i.e. no unplanned reactivity changes have occurred).

In addition, the requirements of the SDM TS ensure adequate SDM in the unisolated RCS.

Due to the above considerations, the safety consequences of this event are insignificant.

E.

Corrective Actions

Operating procedure BwOP RC-8 will be revised to correctly implement the requirements of SR 3.4.18.2 by sampling the isolated RCS loop within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of opening the isolated RCS LSIVs.

This action is due to be completed by January 10, 2003.

A license amendment request will be submitted to incorporate the note from BwOP RC-8 (i.e. "Loop Boron Concentration can be inferred from samples of fill source during loop fill.

As long as no actions to dilute the isolated loop occur between loop fill and opening of stop valves, these results equate to Loop Boron Concentration.") as a note in TS SR 3.4.18.2.

This action is due to be completed in 2003.

F.

Previous Occurrences

Licensee Event Report Number 2001-002-00, "Main Steam Isolation Valves Not Stroke Timed in Mode 3 as Required" was submitted on November 21, 2001 to report that Unit 2 Main Steam Isolation Valves were not stroked in Mode 3 as required by the Technical Specifications.

This was due to a misinterpretation of a TS SR Note during the conversion to improved TS.

The root cause for this event is unknown since the responsible individual could not be interviewed.

However, procedure changes were made to clarify the TS SR implementation.

The current event was not related to the TS conversion process.

G.

Component Failure Data

Manufacturer Nomenclature Model Mfg. Part Number