ML20064F141

/03X-1 on 780510:while Oper at 40% Pwr,Moisture Concentrations in Pcrv Exceeded Limits of 4.2.11.Moisture Was Introduced During Previous Loop 1 Shutdown & Collected in Pcrv Insulation

ML20064F141
Person / Time
Site:	Fort Saint Vrain
Issue date:	11/22/1978
From:	Gahm J PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML20064F139	List: ML20064F137 ML20064F141
References
LER-78-016-03X, LER-78-16-3X, NUDOCS 7811280289
Download: ML20064F141 (4)

Text

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E 60 61 OOMET N lYSER 66 69 EVENT DAT2 REPORT DATE EVENT DESCRIPTION AND PRO 9ABLE CONSEQUENCES h lol2l l While operating at approximately 40% reactor power. moisture concentrations exceeded I 1ol3l l the limits of LCO 4.2.11 for about 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. This constitutes operation under a de- l I o 14 I l graded mode permitted by LCO 4.2.11, and is reportable per Fort St. Vrain Technical  !

Io}sl l Specification AC 7.5.2(b)2. This report submitted as a final supplement to Report l I O Is 1 l No. 50-267/78-16/03-L-0. I 10171 i I T5-f?I y \g g l

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33 3 36 40 42 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l3 jo l Moisture was indroduced into PCRV during previous Loop 1 shutdown, and accumula ted in I

[;,ij l PCRV insulation. Reactor operation evaporated moisture and caused moi =ture inc*anca I

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. * , REPORT DATE: Nov;mbar 22, 1978 REPORTABLE OCCURRENCE 78-16

- . ISSUE 1 OCCURRENCE DATE: May 10, 1978 Page 1 of 3 a

FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 361 PLATTEVILLE, COLORADO 80631 REPORT NO. 50-267/ 78-16/03-X-1 Final Supplement IDENTIFICATION OF OCCURRENCE:

For a period of about 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> on May 10, 1978, the moisture concentration in the PCRV exceeded the limits of Figure 4.2.11-1.

-This constitutes operation in a degraded mode permitted by LCO 4.2.11, and is s

reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2. This re-(/ port is submitted as a final supplement to Reportable Occurrence Report No.

50-267/78-16/03-L-0.

EVENT ,

DESCRIPTION:

As previously reported, a marked increase in the primary coolant moisture con-centration occurred approximately six hours after recovery from a Loop 1 shut-down. Subsequent increases in the moisture concentration resulted in a reactor dew point in excess of that allowed by Figure 4.2.11-1 of the Technical Specifi-ca tions . This condition existed for about 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. During this time the reactor power was reduced and primary coolant flow was increased. Both of these acticns were takea in an effort to reduce the ccre average outlet temperature. Refer to Report No. 50-267/78-16/03-L-0 for further details.

CAUSE (s-', DES CRIPTION:

Recently it was shown that the operation of "A" circulator has been directly re-laced to the moisture and oxidant problems experienced since May 10, 1978. Two possible explanations for this relationship exist:

1) Moisture had been introduced into the PCRV via the "A" circulator upper journal bearing seals during a previous transient.

2) Water had been introduced into the PCRV during the loop shutdown, and had accumulated in the PCRV insulation near the circulator suction plenum. The removal rate of this water depended on the speed of "A" circulator.

, REPORTABLE OCCURRENCE 78-16 ISSUE 1 Pags 2 of 3 CAUSE DESCRIPTION (continued)

Extensive testing supports the second explanation. Apparently, the Loop 1 shutdown introduced water into the PCRV. During the loop recovery, "A" circulator was restarted and began to evaporate liquid water from the PCRV insulation near the circulator inlet. Increasing the primary coolant flow (to lower the core average outlet temperature and increase the permissible reactor dew point) increased the evaporation rate and the primary coolant moisture concentration.

CORRECTIVE ACTION:

Periodic reactor operations specifically designed to remove moisture from the primary coolant have taken place since May,1978. The most effective of these moisture removal operations were conducted throughout most of October,1978.

The reactor was operated at low power levels with "A" circulator running at C_)3 high speed in Loop 1 and "C" and "D" circulators at normal speeds in Loop 2.

This circulator combination maximized the removal rate of water in the PCRV insulation, and initially increased the moisture concentration. However, on October 30, 1978, the moisture concentration began a rapid decline (approximately 1 vpm/ hour) that has continued to the present cancentration of less than 1 vpm.

This indicates that essentially all water has been removed from the PCRV, and no moisture ingress problem exists.

Currently the reactor is operating at about 35% power with a normal circulator line-up. No moisture problems are being experienced. No further corrective action is anticipated or required.

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REPORTABLE OCCURRENCE 78-16

. ISSUE 1 Page 3 of 3 4

Prepared by: b -. t a Charles H. Fuller Technical Services Technician Reviewed by: . -

W. (ahm

/echnical Services Supervisor Reviewed by:

Frank M. Mathie Operations Manager Approved by: Y _

Don Warembourg g Manager Nuclear Production O