05000369/LER-1982-023, Forwards LER 82-023/03L-0.Detailed Event Analysis Encl

Forwards LER 82-023/03L-0.Detailed Event Analysis Encl

ML20052A448
Person / Time
Site:	McGuire
Issue date:	04/08/1982
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20052A449	List: 05000369/LER-1982-023, Forwards LER 82-023/03L-0.Detailed Event Analysis Encl 05000369/LER-1982-023-03, /03L-0:on 820312,after Filling & Venting of RCS, Sample Indicated Boron Concentration at 1,025 Ppm.Caused by Procedural Deficiency Due to Operating Boric Acid Blender W/O Concentration Verification During Addition to RCS
References
NUDOCS 8204280341
Download: ML20052A448 (3)

LER-1982-023, Forwards LER 82-023/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691982023R00 - NRC Website

text

r e e e

DUKE.

WsR COhiPANY Powru Bunt.orwo d[

422 Sourn Cnuncu STazzT; Crunn.oTTE, N. C. 28242

,c"

. April 8, 1982 wlLLIAM O. PA R W F R, J R.

WCF PRESsOENT TELEPHONE:ARE4 704 STEAM PeoouctioN 373-4083 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission l Q, sff Region II

/.Q, la a orgi 3b30 g

C gs'. [.k y

Q

~49, ;O, ',

Re: McGuire Nuclear Station Unit 1 Docket No. 50-369

\\ (9 Cn y

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/82-23. This report concerns T.S.3.1.1.2, "The shutdown margin shall be greater than or equal to 1.0% Delta k/k".

This incident was considered to be of no significance with respect to the health and safety of the public.

Very truly yours, he -

'_ U./

William O. Parker, Jr.

PBN/jfw Attachment cc: Director Records Center Office of Management and Program Analysis Institute of Nuclear Power Operations U. S. Nuclear Regulatory Commission 1820 Water Place Washington, D. C.

20555 Atlanta, Georgia 30339 Mr. P. R. Bemis Senior Resident Inspector McGuire Nuclear Station OFFICIAL COPY M, c4 L

' /

8 2 0 4 2 8G~S% \\

6

)

r O

DUKE POWER COMPANY McGUIRE NUCLEAR STATION REPORTABLE OCCURRENCE REPORT NO. 82-23 REPORT DATE: April 8, 1982 FACILITY: McGuire Unit 1, Cornelius, NC IDENTIFICATION: Reactor Coolant System (NC) Approached Shutdown Margin DISCUSSION: During filling and venting of the NC System on March 12, the boron concentration approached the required shutdown margin, 1030 ppm, for cold shutdown, Mode 5.

Fill sources were the Recycle Holdup Tank B, 18,700 gallons at 1075 ppm boron, and the boric acid blender, approximately 20,000 gallons at an unknown baron concentration. After filling, a Chemical and Volume Control System sample indicated the NC System boron concentration was 1025 ppm.

Immediately the system was declared below the shutdown margin, and approximately 600 gallons of boric acid from Boric Acid Storage Tank A were added to the system. After sufficient recirculation time, a sample was taken and the NC system boron concentration declared above the shutdown margin.

This incident resulted from a Procedural Deficiency, due to the practice of opera-ting the blender without concentration verification during large scale additions to the NC system. In this instance, blending at a concentration less conservative than the shutdown margin, as identified in Section 3.1.1.2 of Technical Specifica-tions, resulted in diluting the NC system boron concentration.

EVALUATION: After the boric acid flow indication in the Control Room appeared faulty, the Chemical and Volume Control System (NV) boric acid flow element (Barton Turbine Rotometer, model 7101) was removed and inspected during the scheduled maintenance outage on March 11.

The turbine blades were found to be missing due to an unknown reason; however, this same phenomenon had been exper-ienced previously. The flow element was replaced and the system returned to ser-vice on March 11, the same day the NC fill through NV began. The new flow element indicated a higher flow than the previous element; therefore, settings for boration were partially based on previous operating experience and the Boration and Dilution Tables. Blending at a lower than expected boron concentration resulted in a fill l

source of approximately 20,000 gallons of low concentration makeup, less than l

1030 ppm boron.

Daily samples indicated the NC system boron concentration was less than expected; however, the Volume Control Tank (VCT) concentration indicated blender output was sufficient to meet the shutdown requirement. The VCT boron concentration apparently had been increased at the blender prior to the daily sample being taken. Filling l

of the NC system was completed shortly after the samples were taken and little i

makeup was required during venting. After the NC pumps were operated, the system concentration was determined to be 1025 ppm boron.

The shutdown margin specification may or may not have been violated, based on the experimental error of ill ppm as per the procedure, " Chemistry Procedure for the l

Determination of Boron in Aqueous Boric Acid Solutions". However, sample data does indicate the shutdown margin was approached and a margin above the requirement was not maintained, i

i t

Report No. 82-23 Page 2

SAFETY ANALYSIS

With T less than 2000F, a 1% delta K/K shutdown margin providesadequateprotechYbntopreventinadvertantcriticalitywithone inoperable control rod.

Based on the calculated shutdown margin and the chemical analyses, the boron concentration approached the shutdown margin after the NC pumps had operated during venting.

If the boron concentration did drop slightly below the 1% shutdowm margin with all control rods operable, the reactor would remain sub-critical due to a conservative safety margin.

The health and safety.of the public were not compromised by this event.

CORRECTIVE ACTION

Immediate boration of the NC system was implemented when the sample indicated a boron concentration less than the shutdown margin. A sufficient volume of boric acid was added to restore the boron concentration well above the required shutdown limit.

Procedure changes will be incorporated to require verification of blender outlet concentration during large scale NC system makeup.

Westinghouse has identified a potential problem with the turbine rotometer blades both at McGuire and at least one other Westinghouse plant. Presently they are evaluating the problem to identify the cause(s) and corrective action (s).

Corrective measures to prevent the boric acid flow element deteriation will be determined utilizing the results of the Wcstinghouse evaluation.

i i

I