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public Service Company ff Odlneardb 16805 Road 19 1/2, Platteville, Colorado 80651-9298 v
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November 23, 1983 Fort St. Vrain Unit No. 1
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_" u' Mr. John T. Collins, Regional Administrator Region IV Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011
Reference:
Facility Operating License No. DPR-34 Docket No. 50-267
Dear Mr. Collins:
Enclosed please find a copy of Reportable Occurrence Report No. 50-267/80-62, Reportable Occurrence Report No. 50-267/83-045, and Reportable Occurrence Report No. 50-267/83-046,
- Finals, and Reportable Occurrence Report No. 50-267/83-011, Revised
- Final, submitted per the requirements of Technical Specification AC 7.5.2(a)9 and Technical Specification AC 7.5.2(b)2.
Also, please find enclosed one copy of the Licensee Event Report for Reportable Occurrence Report No. 50-267/80-62, Reportable Occurrence Report No. 50-267/83-045, Reportable Occurrence Report No. 50-267/83-046, and Reportable Occurrence Report No. 50-267/83-011.
Very truly yours, O, n wave L.,ey h 9 M Gc4 M Don Warembourg Manager, Nuclear Production DW/djm Enclosures cc: Director, MIPC o
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a PDR ADOCK 05000267
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REPORT DATE:
November 23, 1983 REPORTABLE OCCURRENCE 80-62 Determinec ISSUE 1 OCCURRENCE DATE:
October 22, 1980 Page 1 of 7 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEVILLE, COLORADO 80651-9298 l
REPORT NO. 50-267/80-62/01-X-1 l
Final IDENTIFICATION OF OCCURRENCE:
On Thursaay, 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 MWe, it was determined that the isolation valve for the A purification train (HV-2301) would not close either electrically oi by the handjack and was therefore 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 />.
l This event was 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 MWth, 47%
Primary Coolant Pressure 672 psia Temperature 677 F Circulator Inlet Temperature 1,180 F Core Outlet Total Flow 2,430 Klb/hr, 69%
REPORTABLE OCCURRENCE 80-62 s
ISSUE 1 Page 2 of 7 Secondary Coolant Pressure 2,440 psig Temperature 970 F Flow 1,060 Kib/hr, 46%
'I Electrical Power 144 MWe, 42%
DESCRIPTION OF OCCURRENCE:
Fort St.
Vrain has two parallel helium purification trains which remove the impurities from 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 removed from service for regeneration and train 8 placed in service.
Operations personnel placed train B in servfce and then removed train A from service. Train A was isolated from 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 l the primary coolant system at that time.
Operations personnel attempted to close the valve 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 Maintenance personnel again checked the valve controls and attempted to close the valve.
The operator engaged the manual operator with no difficulty and closed the valve.
IHV-2301 was manufactured by Velan Valve Corp.
It is a two inch, l 845 PSIG, stainless steel, Model P-33876-17, electric motor operated, l globe valve.
APPARENT CAUSE OF OCCURRENCE:
l Other l It appeared that the valve operator motor was running but was not l engaged. This indicated possible jamming or interference with the l manual operator.
Subsequent attempts of manual operation proved I successful, indicating possible lack of knowledge / experience as to I the correct method of engaging and manually operating this particular l type valve.
1 REPORTABLE OCCURRENCE 80-62 ISSUE 1 Page 3 of 7 ANALYSIS OF OCCURRENCE:
See Figure 1.
The failure of HV-2301 or HV-2302 to operate must be analyzed for two conditions.
One condition is the postulated permanent loss of forced cooling where one of the two inlet isolation valves, HV-2301 for train A or HV-2302 for train B, must be open so that a depressurization path is available. The second condition is the postulated maximum credible accident which requires that the inlet isolation valve, HV-2301 for train A or HV-2302 for train B, be closed and remain closed if a leak to the purification regeneration system occurs.
The depressurization path required by LCO 4.2.18 is based on the accident analysis of the Final Safety Analyses Report (FSAR) 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 from the primary coolant system is as follows:
A-2301 or A-2302, high temperature filter /adsorbers; HV-2301 or HV-2302, purification inlet isolation valves; E-2301 or E-2302, helium purification coolers; A-2303 or A-2304, helium purification dryers; E-2303 or E-2304, low temperature gas to gas exhangers; A-2305 or A-2306, low temperature adsorbers; E-2303 or E-2304, low temperature gas to gas exchanger; HV-2303 or HV-2304, purification outlet isolation valves; F-2301 or F-2302, purified helium filters;
([) or ($) transferring to the common pump down line to the then at ventilation exhaust system. This depressurization path requirement can be met with either of the purification trains. At the time of this occurrence, both inlet isolation valves were open and depressurization could have been accomplished satisfying the requirements of LCO 4.2.18.
The Maximum Credible Accident (Case 6) described in Section 14.8 of the Final Safety Analysis Report consists of the largest credible identifiable accidental leakage from the primary coolant system, resulting from a multiple failure accident involving the helium purification system regeneration piping.
See Figure 2.
Primary Coolant Leakace Potential.
Leakage of the normally closed valve "A" between a helium purification train and the regeneration equipment could release primary coolant activity to the gas waste surge tanks in the radioactive gas waste system, but only if normally closed valve "B" between the regeneration section and the gas waste system also leaks, and if normally closed valves "C", "D1",
or "02", and "E" in the regeneration section are open. However, this leakage would not lead tc 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 / absorber and the helium purification cooler of the affected train.
REPORTABLE OCCURRENCE 80-62 ISSUE 1 Page 4 of 7 Valve "G"
described here is HV-2301 tur train A and HV-2302 for train B.
With HV-2301 inoperable this leakage could not be remote-manually terminated as described in the Final Safety Analysis Report.
In the Final Safety Analysis Report analysis of a leak from a purification tr:in to the regeneration system the entire purification train is considered as doubly contained and a direct release of activity from this equipment would require at least two unrelated failures.
CORRECTIVE ACTION:
l The valve was manually closed and considered operable on the handjack I at 0830 hours0.00961 days <br />0.231 hours <br />0.00137 weeks <br />3.15815e-4 months <br /> on October 22, 1980.
l On July 1,
1981, during a plant outage for refueling, HV-2301 was l electrically tested and found to operate as designer.
I On July 8,1981, HV-2301 was declared operable either electrically or l manually.
l Manual operation instructions for HV-2301/02 are presently l incorporated in the system operating procedure for the helium l purification system.
l No further corrective action is anticipated or required.
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REPORTABLE OCCURRENCE 80-62 ISSUE 1 Page 7 of 7 Prepared By:
JJsf nc vp, Duane L. Frye f
Senior Technical Services Technician r
Reviewed By:
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d Frank 'JAvachek Tecnnical Services Engineering Supervisor l
Reviewed By:
MdIm ?'Thc4
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Station Manager Approved By:
d&M Don Warembourg Manager, Nuclear Pro ction i