05000267/LER-1980-062, Forwards LER 80-062/01L-0

Forwards LER 80-062/01L-0

ML19340B890
Person / Time
Site:	Fort Saint Vrain
Issue date:	11/05/1980
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19340B891	List: 05000267/LER-1980-062, Forwards LER 80-062/01L-0
References
P-80393, NUDOCS 8011120523
Download: ML19340B890 (8)

LER-1980-062, Forwards LER 80-062/01L-0

Event date:
Report date:
2671980062R00 - NRC Website

text

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.S November 5, 1980 Fort St. Vrain Unit No. 1 P-30393 Mr. Karl V. Seyf rit, Director Nuclear Regulatory Coc=ission Region IV Office of Inspection and Enforcement 611 Ryan Pla::a Drive Suite 1000 Arlington, Texas 76012

REFERENCE:

Facility Cperating License No. DPR-34 Decket No. 50-267

Dear Mr. Seyfrit:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/S0-62/03-L-0, Preliminary, submitted per the requirenants of Technical Specification AC 7.5.2(a)9.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Cccurrence Report No. 50-267/30-62/0 3-L-0.

Very truly yours,

d.

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c-Don W. Ware = bourg Manager, Nuclear Production Fort St. Vrain Nuclear Generating Station DWW/alk OO}

Enclosure 3

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REPORT DATE:

November 5, 1980 REPORTABLE OCCURRENCE 80-62 Determined ISSUE O OCCURRENCE DATE:

Oc tober 22, 1980 Page 1 of 7 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE CC'4PANY OF COLORADO 16805 UEIJ COU:ITY ROAD 191/2 PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/80-62/03-L-0 Preliminary IDENTIFICATION OF OCCURRENCE:

On Thursday, October 21,1980, at 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br />, while the plant was operating at 47'; thermal power and 144 lNe, it was determined that the isolation valve for the A purification train (HV-2301) would not close either electrically or by the handjack and was theref ore considered inoperable at that time. The valve was closed manually using the handjack on October 22, 1980, at 0830 hours0.00961 days <br />0.231 hours <br />0.00137 weeks <br />3.15815e-4 months <br />.

This is reportable per Fort St. Vrain Technical Specification AC 7.5.2(a)9.

CONDITIONS PRIOR TO OCCURRENCE:

Steady State Power The major plant parameters at the time of the event were as follows:

Reactor Power 396:Wth, 47:';

~

Primary Coolant Pressure 672 psia Temperature 677'F Circulator Inlet Temperature 1,130*F Core Outlet Total Flow 2,430 Kib/hr, 69*.

Secondary Coolant Pressure 2,440 psig Temperature 970*F Flow 1,060 Kib/hr, 46%

Electrical Power 144 We, 42*;

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REPORTABLE OCCURRENCE S0-62 ISSUE O Page 2 of 7 DESCRIPTION OF OCCURRENCE:

s Fort St. Vrain has two parallel helium purification trains which remove the impurities f rom the primary coolant on a continuous basis. These trains are alternated as required with one train being in service while the other is shutdown to allow activity to decay and the train to be regenerated.

On October 21, 1980, it was determined the in service train, A, should be re-i moved from service for regeneration and train 3 placed in service. cperations personnel placed train 3 in service and then removed train A from service.

Train A was isolated f rom the purified helium system by closing HV-2303, the outlet isolation valve. Due to the inability to close HV-2301, train A could not be isolated from the primary coolant system at this time. Operations per-sonnel attempted to close the val"e manually, but could not get the manual operator engaged and therefore declared the valve inoperable at 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br />.

On October 22,1980, at 0830 hours0.00961 days <br />0.231 hours <br />0.00137 weeks <br />3.15815e-4 months <br />, Operations personnel and Electrical !!ain-tenance personnel again checked the valva controls and attempted to close the valve. The operator engaged the manual operator with no dif ficulty and closed the valve.

APPARENT CAUSE OI OCCURRENCE:

Design The actual cause of the operator f ailure cannot be deternined at this time be-l cause the valve is in a penetration in the PCRV top head and is inaccessible during reactor operation.

ANALYSIS OF GCCURRENCE:

From the electrical analysis of the valve, it appears that the valve operator motor is running but is not engaged. This indicates possible j amming or in-cerference with the manual operators. The valve has not been tested since it was closed manually, so it cannot be determined if the manual operation has corrected the problem.

See Figure 1.

The failure of HV-2301 or HV-2302 to operate must be ansty:ed for~two condicions. One condition is the postulated permanent loss of forced cooling where one of the two intet isolation valves, HV-2301 for train A or HV-2302 f or train 3, must be open so that a depressurization path is available.

The second condition is the postulated maximum credible accident which requires that the intet isolation valve, HV-2301 for train A or HV-2302 for train 3, be closed and remain closed if a leak to the purification regeneration system occurs.

REPORTA3LE OCCURRENCE 80-62 ISSUE D Page 3 of 7 ANALYSIS GF OCCURRENCE (continued):

The depressuriration path required by LCO 4.2.18 is based on the accident analysis of the Final Safety Analysis Report (7SAR) which requires that in the event of a permanent loss of forced cooling, the PCRV must be vented via the purification train. This depressurization path f rom the primary coolant systen is as follows: A-2301 or A-2302, high cenperature filter /adsorbers; HV-2301 or HV-2302, purifica tion inlet isolatier, valves; E-2301 or E-2332, helium purification coolers; A-2303 or A-2304, helium purification dryers; E-2303 or E-2304, low temperature gas to gas exchangers; A-2305 or A-2306, low temperature adsorbers: E-2303 or E-2304, low temperature gas to gas ex-mon pump down line to the ventilation exhau(}s)t system.

F-2302, purified helium filters; then at or This depressuritation path requirement can be met with either of the purification trains. At the time of this occurrence, both inlet isolation valves were open and depressuri-zation could have been accomplished satisfying the requirements of LCO 4.2.18.

The Maximum Credible Accident (Case 6) cescribed in Section 14.8 of the Final Saf ety Analysis Report consists of the largest credible identifiable accidental leakage frem the primary coolant system, resulting f rom a multiple f ailure accident involving the helium purification system regeneratien piping.

See Figure 2.

Primary Coolant Leakage Potential.

Leakage of the normally closed valve "A" between a helium purification train and the regeneration equipment could release primary coolant activity to :he gas vaste surge tanks in the radioactive gas waste system, but only if normally closed valve "B" be-tween the regeneration section and the gas waste system also leaks, and if normally closed valves "C", "Dl".

or "D2",

and "E" in the regeneration section are open. However, this leakage would not lead to uncontrolled release of activity to the atmosphere, and would be terminated with remote-manual closure of the normally open isolation valve "G" between the high temperature filter /ab-sorber and the helium purification cooler of the af f ected train.

Valve "G" described here is HV-2301 for train A and HV-2302 for train 8.

With HV-2301 inoperable this leakage could not be remote-manually terminated as described in the Final Safety Analysis Report.

In the Final Saf ety Analysis Report analysis of a leak f rom a purification train to the regeneration system the entire purification train is considered as doubly contained and a direct release of activity from this equipuent would require at least two unrelated f ailures.

CCRRECTIVE ACTION:

The valve was manually closed and is now considered operable on the handjack.

A determination of remote-manual operability will be made when plant condi-tions permit. The results of this determination vill be included in a future supplemental report.

• • g 4

REPORTABLE OCCURRE CE 80-62 ISSUE O Page !. of 7 CORRECTIVE ACTION (continue d:

In addition the Nuclear Projects Department will be asked to investigate pos-sible further eodifications to lessen chances of valve inoperability.

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Amendme n t 26

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1 REPORTABLE OCCURRENCE 80-62 ISSUE O l

Page 7 of 7 E

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Prepared by:

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