Text

Forwards LER 82-011/03L-0.Detailed Event Analysis Encl
	ML20052H983
Person / Time
Site:	Fort Saint Vrain
Issue date:	05/12/1982
From:	Warembourg D; PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins; NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20052H984	List: ML20052H983; ML20052H988;
References
	P-82138, NUDOCS 8205240273
	Download: ML20052H983 (9)
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public Service Company CfOdamb l 5L -

d 16805 Road 19 1/2, Platteville, Colorado 80651-9298 1

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May 12, 1982 l Fort St. Vrain l Unit No. 1 P-82138 i o

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l MAY 171982 f : I Mr. John T. Collins, Regional Administrator L hb/

t Region IV Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011 1

Reference:

Facility Operating License ,

No. DPR-34 l 1

Decket No. 50-267

Dear Mr. Collins:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/82-011, 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 l Reportable Occurrence Report No. 50-267/82-011.

Very truly yours, 1

l s mu/ m a7 a l

o. , w - ,_ L...,

Don Warembourg l

Manager, Nuclear Production l

l DW/cis Enclosure cc: Director, MIPC l

l 8205240273 820512 64i PDR ADOCK 05000267 5 pon

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REPORT DATE: May 12. 1932 REPORTABLE OCCURRENCE 82-011 i ISSUE 0 OCCURRENCE DATE: Acril 12. 1982 Page 1 of 8 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEVILLE, COLORADO S0651-9298 REPORT NO. 50-267/82-011/03-L-0 4

i Final

, IDENTIFICATION OF

! OCCURRENCE:

During the period April 12, 1982, to April 20, 1982, with the reactor at power operation, the plant was operated in a degraded mode of LCO 4.2.11 on three separate occasions and LCO 4.2.10 on one occasion. These events are reportable per Fort St. Vrain Technical i

Specification AC 7.5.2(b)2.

EVENT l DESCRIPTION:

Event #1 i

With the reactor operating at approximately 10% power, the moisture level measured by dewpoint exceeded limits set by LCO 4.2.11. At 2200 hours0.0255 days 0.611 hours 0.00364 weeks 8.371e-4 months , April 12, 1982, with an average core outlet temperature of 754 F, the calculated reactor dewpoint was -15*F. This is in the

" limited acceptable" region of Figure 4.2.11-1 of LCO 4.2.11. This condition continued until 0912 hours0.0106 days 0.253 hours 0.00151 weeks 3.47016e-4 months on April 13, 1982, when the reactor scrammed, making LCO 4.2.11 not applicable. (See Table 1)

Event #1 With the reactor operating at approximately 5% power, the moisture level measured by dewpoint again exceeded LCO 4.2.11 limits. At 0400 hours0.00463 days 0.111 hours 6.613757e-4 weeks 1.522e-4 months on April 14, 1982, with an average core outlet temperature of 747 F, the calculated reactor dewpoint was -2 F. This is in the

, " limited acceptable" region of Figure 4.2.11-1 of LCO 4.2.11. This condition persisted until 2200 hours0.0255 days 0.611 hours 0.00364 weeks 8.371e-4 months the same day, when the reactor dewpoint entered the "non-acceptable" region of Figure 4.2.11-1 of '

LCO 4.2.11. The dewpoint remained in this region for a total of

]

12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months , when at 1000 hours0.0116 days 0.278 hours 0.00165 weeks 3.805e-4 months on April 15, 1982, the calculated i dewpoint returned to the limited acceptable region. At 1545 hours0.0179 days 0.429 hours 0.00255 weeks 5.878725e-4 months on April 15, 1982, the reactor scrammed, thereby making LCO 4.2.11 not applicable. (See Table 1)

I

_ . _ . . = - - . _=_ . . __. .

l REPORTABLE CCCURRENCE 82-011 ISSUE 0 Page 2 of 8 4

Event #3 At 2000 hours0.0231 days 0.556 hours 0.00331 weeks 7.61e-4 months on April 16, 1982, with the reactor operating at approximately 15% power, the limits of LCO 4.2.11 were exceeded once again. With the average core outlet temperature at 1041 F, the calculated reactor dewpoint of -19'F resulted in operation in the .

"l i.ni ted acceptable" region of Figure 4.2.11-1 of LCO 4.2.11. This

'. condition of limited acceptable continued until 1600 hours0.0185 days 0.444 hours 0.00265 weeks 6.088e-4 months on April 18,1982. At that time, the reactor dewpoint had noved into the " acceptable" region of Figure 4.2.11-1 of LCO 4.2.11. (See Table 1)

Event #4 At 1805 hours0.0209 days 0.501 hours 0.00298 weeks 6.868025e-4 months on April 19, 1982, with the reactor at approximately l 28% power, the average core outlet temperature increased above 1200 F. This temperature made LCO 4.2.10 applicable and LCO 4.2.11

, not applicable. LCO 4.2.10 restricts operation to under 10 parts per million (ppm) of total oxides which includes carbon monoxide (CO),

carbon dioxide (CO2 ), and water (H 2O). The chemistry sample taken at 1815 hours0.021 days 0.504 hours 0.003 weeks 6.906075e-4 months indicated 0 ppm of CO, 29.9 ppm of CO 2, and 6.4 ppm of H2 0, for a total oxidant ppm of 36.3. This constituted a degraded mode of LC0 4.2.10. Forty minutes later, at 1845 hours0.0214 days 0.513 hours 0.00305 weeks 7.020225e-4 months , the average core outlet temperature was decreased below 1200 F, making LCO 4.2.10 i no longer applicable. (See Figure 1)

I CAUSE DESCRIPTION:

The reactor plant had been in a shutdown or low power operation condition over a five month period for a major system modification l outage. During this period, the prestressed concrete reactor vessel

had been at subatmospheric pressure several times for various activities. These conditions allowed for a gradual buildup of moisture within the prestressed concrete reactor vessel. Subsequent i operation caused off gassing of the moisture from the core graphite, which resulted in the four events.

CORRECTIVE ACTION: ,

Events #1 and #2 I

The reactor scrammed during both of these events making LCO 4.2.11 no longer applicable.

._. - _ . . _. ._ _ . . _ _ _ _ . . _ . _ . _ _ . . .~._ _ _, ._.

T REPORTABLE OCCURRENCE 32-011 ISSUE O Page 3 of 8 Event #3 Reactor power was reduced to allow off gassing of the moisture to stabilize. Normal operation of the purification system subsequently reduced the moisture level, measured by dewpoint, to the " acceptable region" of Figure 4.2.11-1 of LCO 4.2.11.

Event #4 Reactor power was reduced to decrease the average core outlet temperature below 1200 F. Once back below 1200*F, LCO 4.2.10 was no longer applicable.

No further corrective action is anticipated or required.

) .

T*

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! REPORTABLE CCCURRENCE 82-011 ISSUE 0 Page 4 of 8 t

TABLE 1 l l l l Average Corel l l j l I 10utlet Temp-lCalculated Reactor l Figure 4.2.11-1 I I Date l Time!erature (*F)I Dewooint (*F) ! Region I l I i l l l 14-12-8212000l 683 l -16 l Acceptable [ '

[.___________________________ Event 1----------------------------I

! I I I I I I l 122001 754 l -15 l Limited Acceptable l 1 I I I I i

! !4-13-82l00001 870 1 -12 iLimited Acceptable l !

l l l 1 l l l 102001 1001 l -7 l Limited Acceptablel I I, I I I I l l04001 978 l 8 l Limited Acceptablel I I I I I i l l06001 989 1 7 ILimited Acceptable l l l 1 1 I I I 108001 985 l 10 [ Limited Acceptablel

1 I I I I i i 10912l Reactor Scram - LCO 4.2.11 No Longer Applicable I

I l l l l l j I4-14-82102001 666 I -7 l Acceptable I l----------------------------Event 2----------------------------I I I I I I i l 104001 747 l -2 l Limited Acceptablel

I I I I I i .

l 106001 940 l -1 [ Limited Acceptablel i I I I I I l 10800] 978 l -2 Ilimited Acceptablel I I I I I I

1 110001 1075 l -1 l Limited Acceptablel

! l I I l l l l 1 112001 1063 l 1 l Limited Acceptable l i l I I I I I i 114001 1031 1 3 l Limited Acceptablel

I I I I I I I l16001 1006 1 5 ILimited Acceptablel l I I I I I i 118001 1024 l -3 l Limited Acceptablel i l I I I l l l20001 1035 l 4 l Limited Acceptablel l I i i l l

I I22001 1105 1 0 INon-Acceptable l

1' REPORTABLE OCCURRENCE S2-011 i ISSUE O Page 5 of 8 i

l TABLE 1 (Cont'd) i I l l Average Corel I l 1 l 10utlet Temp-lCalculated Reacturl Figure 4.2.11-1 1

l Date lTimet erature ( F); Dewooint (*F) l Region i 1 l l l 1 I l

14-15-82100001 1108 l 7 lNon-Acceptaole [ .

! I I I l l l l l0200l 1110 1 7 INon-Acceptable I i' I I l I I l l l0400l 1104 l 7 lNon-Acceptable l j l l I l I l I 106001 1121 l 7 lNon-Acceptable l 1 l l l l l l l08001 1103 1 6 lNon-Acceptable l l l 1 l 1 I l l1000l 1074 l -2 l Limited Acceptablel l I l i I I I

1 l12001 1048 l -2 Ilimited Acceptable l >

I i 1 I l l

, l l1400l 1038 l -1 l Limited Acceptable l l l I l l I i l 11545l Reactor Scram - LCO 4.2.11 No Longer Applicable l l l l l l l l4-16-8211800l 1011 l -23 l Acceptable I

! l----------------------------Event 3----------------------------l 1 l l l I I I l Limited Acceptable l l l2000l 1041 l -19 l 1 l 1 1 I I i 12200l 1054 l -16 ILimited Acceptablel l l l l l I 14-17-82100001 1061 l -16 l Limited Acceptablel I I I I I l l l02001 1075 I -16 Ilimited Acceptablel l I I I I I l l04001 1063 l -13 l Limited Acceptable l 1 l l l I I l 10600l 1091 1 -12 [ Limited Acceptable l l l l l l l I

i 108001 1068 l -10 l Limited Acceptable'

I I l l l l l l10001 1060 1 -11 (Limited Acceptablel l l 1 l l l l 11200l 1077 1 -11 l Limited Acceptable l l l l l l l l l

l l14001 1117 l -10 lLimited Acceptable l l

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. T REPORTABLE OCCURRENCE 32-011 ISSUE O Page 6 of 3 TABLE 1 (Cont'd) l l l Average Corel l l l l 10utlet Temp-l Calculated Reactori Figure 4.2.11-1 l l Date ITimelerature (*F)I Dewooint PF) l Region l I I I I I I l 11600l 1102 1 -12 l Limited Acceptablel I I I l I I l l1800l 1103 l -12 ILimited Acceptable l l l l I l l l l2000l 1111 l -12 l Limited Acceptable l l l l l l l l l2200l 1106 l -15 l Limited Acceptable l l l 1 I I I l4-18-82100001 1112 l -15 l Limited Acceptable l 1 l 1 I I l l l02001 1129 l -15 l Limited Acceptable l 1 l 1 l l l l l0400l 1113 l -14 l Limited Acceptable l l l l l l l l l0600l 1112 l -15 l Limited Acceptable l l I I I I l l 108001 1114 l -15 l Limited Acceptable l l l l 1 l l l l1000l 1130 l -15 l Limited Acceptable l l l l l 1 l l 11200l 1107 l -18 l Limited Acceptablel l I l l l 1 l 11403l 1103 l -19 l Limited Acceptablel i I I I I I i 116001 1099 l -22 l Acceptable l l

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4 i REPORTABLE OCCURRENCE 82-011 i ISSUE O Page 8 of 8 1

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P;epared By: i " k , O r> - M OwenJ.C@ ton O Technical services Technician i

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Reviewed By: M Charles Fuller

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Reviewed By: E.f "Jf,'// 2, w#W c44 Edwin D. Hill 7

, Station Manager i

Approved By: 0- , LJ u e La n , -1 n :1} 1rj d A

! Don Waremocurg

! Manager, Nuclear Production i

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ML20052H983

Text

Reference:

Dear Mr. Collins:

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