05000267/LER-1983-012, Forwards LER 83-012/03L-0.Detailed Event Analysis Encl

Forwards LER 83-012/03L-0.Detailed Event Analysis Encl

ML20073J624
Person / Time
Site:	Fort Saint Vrain
Issue date:	04/07/1983
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20073J626	List: 05000267/LER-1983-012, Forwards LER 83-012/03L-0.Detailed Event Analysis Encl 05000267/LER-1983-012-03, /03L-0:on 830308-15,reactor Dewpoint Exceeded Limits Three Times.Caused by Plant Upsets Resulting in Increased Moisture Levels & Subsequent Vaporization Exceeding Helium Purification Sys Removal Rate
References
P-83138, NUDOCS 8304190349
Download: ML20073J624 (6)

LER-1983-012, Forwards LER 83-012/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2671983012R00 - NRC Website

text

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public service company ce Odetrsde vn 16805 Road 19 1/2, Platteville, Colorado 80651-9298 April 7, 1983 Fort St. Vrain Unit No. 1 P-83138

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APR I i 1983 Mr. John T. Collins, Regional Administrator h:"

Region IV L-Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Reference:

Facility Operating License No. DPR-34 i

Docket No. 50-267

Dear Mr. Collins:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/83-012, Final, submitted per the requirements of Technical Specification AC 7.5.2(b)2.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Occurrence Report No. 50-267/83-012.

Very truly yours, Don Warembourg Manager, Nuclear Production DW/cis Enclosure cc:

Director, MIPC b

8304190349 830407 PDR ADDCK 0500026 S

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M REPORT DATE:

Aoril 7. 1983 REPORTABLE OCCURRENCE 83-012 ISSUE O CCCURRENCE DATE:

March 8, 1983 Page 1 of 4 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEVILLE, COLORADO 80651-9298 REPORT NO. 50-267/83-012/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

During the period March 8, 1983, through March 15, 1983, with the reactor operating and the average core outlet temperature between 725 and 1200 degrees fahrenheit, the reactor dewpoint exceeded the limits set forth by Figure 4.2.11-1 of LCO 4.2.11 on three separate occasions. Also during the sama period, with the average core outlet temperature greater than 1200 degrees fahrenheit, the total primary coolant oxidants exceeded limits set forth by LCO 4.2.10 on three separate occasions. All events constitute operation in a degraded mode of either LCO 4.2.11 or LCO 4.2.10 and are reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2.

EVENT

DESCRIPTION

Event #1 At 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on March 8, 1983, with the reactor operating at power and an average core outlet temperature near 970 degrees fahrenheit, the calculated reactor dewpoint entered the "non-acceptable" region of Figure 4.2.11-1 of LCO 4.2.11.

This condition existed until 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br /> on March 9, 1983, when the dewpoint returned to the

" limited acceptable" region.

The highest dewpoint reached was 51 degrees fahrenheit at an average core outlet temperature of 1030 degrees fahrenheit.

Event #2 At 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> on March 9, 1983, with the reactor operating at power and an average core outlet temperature near 1065 degrees fahrenheit, the calculated reactor dewpoint again entered the "non-acceptable" region of Figure 4.2.11-1 of LC0 4.2.11.

This condition existed until 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on March 10, 1983, when the dewpoint returned to the

" limited acceptable" region.

The highest dewpoint reached was 30 degree-fahrenheit at an average core outlet temperature of 1071 degrees fahrenheit.

s rep 0RTABLE OCCURRENCE 83-012 ISSUE O Page 2 of 4 Event #3 At 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br /> on March 11, 1983, with the reactor operating at power and the average core outlet temperature near 1004 degrees fahrenheit, the calculated reactor dewpoint again entered the "non-acceptable" region of Figure 4.2.11-1 of LCC 4.2.11.

This condition existed until 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> the same day when the dewpoint returned to the

" limited acceptable" region.

The highest dewpoint reached was 23 degrees fahrenheit at an average core outlet temperature of 1004 degrees fahrenheit.

Event #4 At 1115 hours0.0129 days <br />0.31 hours <br />0.00184 weeks <br />4.242575e-4 months <br /> on March 14, 1983, with the reacter operating at power, the average core outlet temperature increased beyond 1200 degrees fahrenheit with total primary coolant oxidants (sum of water, carbon monoxide, and carbon dioxide) above the 10 parts per million (ppm) limit of LCO 4.2.10.

This condition continued until 1230 hours0.0142 days <br />0.342 hours <br />0.00203 weeks <br />4.68015e-4 months <br /> the same day when the average core outlet temperature dropped below the 1200 degrees fahrenheit limit of LCO 4.2.10.

The highest oxidant concentration reached was 16.9 ppm.

Event #5 At 1515 hours0.0175 days <br />0.421 hours <br />0.0025 weeks <br />5.764575e-4 months <br /> on March 14, 1983, with the reactor operating at power, the average core outlet temperature again increased beyond 1200 degrees fahrenheit with total primary coolant oxidants atave the 10 ppm limit of LC0 4.2.10.

This condition continued until 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br /> the same day when the average core outlet temoerature dropped below the 1200 degree fahrenheit limit of LCO 4.2.10.

The highest oxidant concentration reached was 13.2 ppm.

Event #6 At 1900 hours0.022 days <br />0.528 hours <br />0.00314 weeks <br />7.2295e-4 months <br /> on March 14, 1983, with the reactor operating at power, the average core outlet temperature again increased beyond 1200 degrees fahrenheit with total primary coolant oxidants above the 10 ppm limit of LCO 4.2.10.

At 1015 hours0.0117 days <br />0.282 hours <br />0.00168 weeks <br />3.862075e-4 months <br /> on March 15, 1983, total primary oxidants exceeded 100 ppm. This condition continued until 1945 hours0.0225 days <br />0.54 hours <br />0.00322 weeks <br />7.400725e-4 months <br /> on the same day when the average core outlet temperature dropped below the 1200 degree fahrenheit limit of LCO 4.2.10.

The highest oxidant concentration reached was 289.8 ppm.

DESCRIPTION

Moisture was introduced into the prestressed concrete reactor vessel as the result of a buffer helium system upset which occurred on February 15, 1983, following an electrical system upset.

When subsequent startup operations commenced and primary coolant temperatures increased, the vaporization rate of the water which was present in the reactor vessel increased to a point where moisture was

s REPORTABLE OCCURRENCE 83-012 ISSUE O Page 3 of 4 being entrained in the primary coolant fa:ter than the helium purification system could remove it.

CORRECTIVE ACTION:

In the first three events, the helium purification system was used to reduce the reactor dewpoint to within the " limited acceptable" region of Figure 4.2.11-1 of LCO 4.2.11 for the appropriate average core outlet temperature.

In the last three events, the average core outlet temperature was reduced below 1200 degrees fahrenheit, making LCO 4.2.10 no longer applicable.

No further corrective actions are anticipated or required.

O O

REPORTABLE OCCURRENCE 83-012 ISSUE O Page 4 of 4 G

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Prepared By:

ltize Owen J.(Clayton d Senior fedhnical 36rvices Technician b

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Reviewed By:

A x Frank"J/NovaBek Techni(al Services Engineering Supervisor Reviewed By:

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- f L. M. McBride

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Station Manager l

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Approved By: b 2[d(N Oon Warembour( '

Manager, Nuclear Production l

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