Text

Forwards LER 80-067/01X-1.Detailed Event Analysis Encl
	ML19352B183
Person / Time
Site:	Fort Saint Vrain
Issue date:	04/30/1981
From:	Warembourg D; PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K; NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19352B184	List: ML19352B183; ML19352B206;
References
	P-81135, NUDOCS 8106030278
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Mr. Karl V. Seyfrit, Director

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Region IV d,y

.. d /j \ p Office of Inspection and Enforcement 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76012 Re fe rence : Facility Operating License No. DPR-34 Docket No. 50-267

Dear Mr. Seyfrit:

Enclosed please find a copy of Paportable Occurrence Report No. 50-267/

80-67, Final, submitted per the requirements of Technical Specification AC 7.5.2 (a)2.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Occurrence Report No. 50-267/80-67.

Very truly yours,

&C%/s Don Warembourg Manager, Nuclear Production DW/ cis Enclosure cc: Director, MIPC 007 5

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.L' OCCI'RRENCE REPORT DISTRIBUTION Number of Cootes De pa r tme n t o f E ne r gy - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 (P Letter)

San Francisco Operations Of fice Atta: California Patent Group 1333 Broadway Oakland, California 94612 De p ar tmen t o f Ene rgy - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

ltr. Glen A. Newby, Chief 1 (P Letter) dTR 8tanch Division of :Tucletr Power Development w

..a11 Station 5-107 washington, D.C. 20545 Depar tment o f Ener gy - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 (P Letter) ,

Atts: Project Manager 110 Vest A Street. Suite 460 San Diego, California 92101 6 Mr. Karl V. Seyfrit Director .------------------------ 1 (original of P Letter Region IV and Copy of LER) ,

office of Inspection and Enforcement Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76012 Di re c t o r - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 (P Letter, IIR)

Office of Management Infornation and Program "introl U. S. Nuclear Regulatory Consnission Washington. D.C. 20555 Mr . 'xich a rd Phe lp s - _ . - - . . . . - ~ . ..

TSV. CA. Site J '- - - - - - - - - - - - - - - - - - - - - - - - - - - - 10 (Original of F?LG Letter-Representative plus Two Copies. One

".,eneral Aconic Company Copy of P Letter. One

?. O. Sox a26 Copy of LER)

Platteville, Colorado 80651 Mr . S i l l Lava te e - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 (P Letter. LER)

Nuclear Safety Analysis Center 3412 E111 view Avenue P. C. Sox 10412 Palo Alto. California 94303 NRC Resident Site Inspector -------------------------- 1 7 Letter. LER) i I

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l REPORT DATE: April 30, 1981 REPORTABLE OCCURRENCE 80-67 Determined ISSUE 1 OCCURRENCE DATE: November 7,1980 Page 1 of 7 R)RT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE CONPANY OF COLORADO 16805 WELD COUNTT ROAD 191/2 PLATIEVILLE, COLORADO 80651 REPORT NO. 50-267/fJ-67/01-X-1 Final IDENTIFICATION OF OCCURRENCE:

On Friday, November 7,1980, at 0740 hours0.00856 days 0.206 hours 0.00122 weeks 2.8157e-4 months , it vs.s determined that the con-centration of critium in an unrestricted area following radioactive liquid release number 412, which was made on October 23, 1980, exceeded the limit specified in LCO 4.8.2(a). At the time of the occurrence, the plant was operating at less than 2% thermal power.

This event is reportable per Fort St. Vrain Technical Specification AC 7.5.2(a)2.

CONDITIONS PRIOR TO OCCURRENCE:

The conditions prior to occurrence or at the time of reportability deter-mination are not germane to this report.

DESCRIPTION OF OCCURRENCE :

During an analysis by plant personnel of the results of samples associated with radioactive liquid waste release number 412, it was determined that the concentration of tritium in an unrestricted area exceeded the limit specified in LCO 4.8.2(a) .

Refer to Figure 1. Eff uents from the reactor building sump ( ) and the liquid waste system ( B ) are dischargea to a common line ( ) leading to the Goosequill Ditch ( D ). Circulating water blowdown ( ) is ad-mitted for dilution purposes prior to the effluent reaching *he Goosequill ,

Ditch. Radiation monitors RIS-6212 and RIS-6213 ( 1 and 2 ) in the com- j mon discharge line alarm at preset values on high activity in effluent dis-charged from either the reactor building sump or the liquid wast system i

and provid signal to trip the liquid waste transfer pumps ( 3 ), close HV-6212 ( , and if the release is from the reactor building sump, close HV-7204-2 ( ), thus terminating the release.

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a Pr?ORTABLE OCCURRENCE 80-67

.IS3UE 1 Fage 2 of 7 DESCRIPTION OF OCCURRENCE: (Cont'd)

Circulating water blowdown flow is monitorsd by flov switch FSL-4101 ( @ )

and at a preset value of low blowdown flow provides a signal to close HV-6212 sump pumps and( hto) trip

( )theonliquid Figurewaste 1). transfar pungis and reactor building Under normal conditions, discharge from the teactar building sump (Sys-tem 72) is at a flow rate less than or equal to 10 gpm. However, discharges at a rate in excess of 10 gpm (up to a maximua of approximately 50 gpm with one reactor building sump pump in service) can be ande, provided the sump contents are previously analyzed to assure compli. tace with CO 4.8.2 and

- 4.8.3. Flow race is then increased by opening a bypass ( 8 ) in parallel with the radiation monitors. Under these conditicus, a proportionate sample flow continues to pass through the radiation. monitors to provida a means for termination of the release on high activity by cluing HV-6212 and HV- 4-2 and directing the effluent to the liquid waste syecem via HV-7204-1 ( ).

Releases from the liquid waste system (System 62) are governed by the re-quirements of Technical Specification LCO 4.8.2. P rior to release, a maxi-mum discharge rate is established based on radionue Lide concentrations in the liquid waste effluent. Based on the calculated release rate, it may be necessary to increase the blowdown flow to greater :han the nominal 1100 gpm to provide sufficient dilution to ast are that radicauclides in concentrations greater than MPC are not released to unrestricted l areas. It may also be necessary to change the trip setpoints of the radiation monitors or to re-duce the allowable release rate to assure that thd discharge is within the specified limits. l

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However, the design of the liquid waste system dill not take into account the effects of an oil separator ( h ) in the discharge line common to the re-l actor building sump and liquid waste discharge sylst.em. The oil separator has a capacity of approximately 3200 gallons; the! normal volume of a liquid waste release is in the range of 2200 to 2300 gal!1ons. As detailed in Re-portable Occurrence 80-52, it is conceivable that! .a good portion of the volume of a liquid waste release could be held upl En the oil separator down-stream of the monitoring equipment.

Furthermore, if a release from the reactor buildbg sump were to be made fol-lowing a liquid waste release at a release rate higher than that allowable for the liquid waste release, the radioactive li' quid which had been held up in the oil separator would be released at an unalcceptable release rate.

This higher release rate would result in a small.ee dilution factor than origisally calculated for the liquid waste reles.sa. This reduced dilutics I could result in discharges to the unrestricted area in excess of the allowable radionuclide concentrations contained in LCO 4 lL2(a).

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REPORTABLE OCCURRENCE 80-67 ISSUE 1 )

Page 3 of 7 i DESCRIPTION OF OCCURRENCE: (Cont'd)

In order to ensure against a possible violation of the limits of LCO 4.8.2(a),

as a result of the above-mentioned circumstances, Deviation #80-445 to Sur-veillance Procedure SR 5.8.2bc-M, " Radioactive Liquid Effluent System Instru-mentation Functional Test" was prepared and was subsequently approved by the Plant Operations Review Committee on October 10, 1980. This deviation calls for initiating a 6000 gallon release from the reactor building sump innedi-ately after terminating a liquid waste release. (See corrective action #1 of RO 80-52) . The release rate from the sump is to be less than or equal to the release rate authorized for the liquid wasta release. This procedure has been followed on liquid waste releases made subsequent to Orober 10.

In addition to the above flush of the oil separator, on October 21, 1980, an order was placed in the Health Physics Order-Book calling for the collection of cooling tower blowdown samples 'once per two hours during the last half of the liquid wasta release and for the entire duration of the reactor building sump release (see corrective action #2 of R0 80-52).

Liquid waste release number 412 was initiated at 1730 hours0.02 days 0.481 hours 0.00286 weeks 6.58265e-4 months on October 22, 1980, and secured at 0623 hours0.00721 days 0.173 hours 0.00103 weeks 2.370515e-4 months on October 23, 1980. The recommended re-lease rate was 3.0 gpm, with a cooling tower blowdown (dilution) rate of 2300 gpm. Subsequent analysis indicated a calculated release rate of 2.6 gpm and a calculated blowdown rate of 2733 gpm. Due to an apparent clog in the reactor building sump discharge line, the flush was not begun until approximately 1645 hours0.019 days 0.457 hours 0.00272 weeks 6.259225e-4 months on October 23, and was secured at 1800 hours0.0208 days 0.5 hours 0.00298 weeks 6.849e-4 months on October 24. The reactor building sump flow rate was adjusted by operations personnel so that the sump -flow rate recorder, FR-7216, read approximately 3 gpm. Subsequent to the oil separator flush, an analysis of the reactor building sump flow integrator, FIQ-7215, indicated that the flush had been performed at an average release rate if 4.8 gpm,1.8 gpa greater than the reconsmanded release rate.

Health Physics personnel collected liquid samples, per the Health Physics Order, during the liquid waste release and subsequent flush. Subsequen t analysis of the sample taken at 1800 hours0.0208 days 0.5 hours 0.00298 weeks 6.849e-4 months on October 23 indicated a tritium concentration in the unrestricted area of 3.23E-3 uC1/cc. The limiting con-centration of tritium per LCO 4.8.2(a) is 3.00E-3 uCi/cc in the unrestricted area. Results of samples taken prior to and subsequent to the 1800 hours0.0208 days 0.5 hours 0.00298 weeks 6.849e-4 months sample indicated tricium concentrations within the limit of LCO 4.8.2(a).

It should be noted that the sample indicating a concentration of tritium ex-ceeding the limit of LCO 4.8.2(a) was taken from the Goosequill Ditch, con- I sidered to be in the unrestricted area, although located "t Public Service Company of Colorado property. The Goosequill Ditch flows into a 25 acre farm pond, also on Company property, the overflow of which drains into the South Platte River. The additional dilution provided by the pond ensures that the concentration of liquid flowing into the South Platte River is within the limits of LCO 4.8.2(a).

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1 REPORTABLE OCCURRENCE 80-67 ISSUE 1 Page 4 of 7 i

APPARENT CAUSE 0F OCCURRENCE:

' Deviation #80-445 to SR 5.8.2bc-M was inadequate as written to avoid prob-less arising from the design of the reactor building sump discharge system.

ANALYSIS OF OCCURRENCE:

Deviation !80 445 to Surveillance Procedure Number SR 5.8. Ibe-M was written to address the concerns raised in Reportable Occurrence RO 80-52 with respect to the possibility of exceeding the limits of LCO 4.8.2(a), concentrations of radioactive liquid in an unrestricted area. The deviation calls for a 6000 ganon flush of the oil separator in the discharge line common to the reactor building sump and liquid waste discharge systems, following a radi-oactive liquid waste relense, at a rate less than or aqual to the recommended -

liquid waste release rate.

Following liquid waste release number 412, operations personnel correctly fonowed the requirements of SR 5.8.2bc-M and left HV-6212 ( 04 ) in the open position. Upon initiation of the reactor building sump release, oper-ations personnel again correctly followed SR 5.8.2bc-M and attempted to con-trol the release rate by throttling the controner for HV-6212, HC-6212, located on the 4771' elevation of the Reactor Building, by hand, while a Reactor Operator in the Control Room observed the flow race meter FR-6217.

FR-6217 is a linear flow rate recorder with a range of 0 - 125 gpm, incre-mented by 2.5 gpm. Accurate confirmation of a small (less than 5 gpm) re-lease rate using FR-6217 is not possible. This inability to accurately es-tablish the 3.0 gpa allowable release rate from the reactor building sump contributed to exceeding the limit of LCO 4.8.2(a).

Another problem area involves the possibility of obstructions in the reactor building sump discharge system, as noted under the " Description of Occur-rence" portion of this report. It is possible that the sump flow rate could be established while an obstruction existed in the discharge line.

Subsequently, the obstruction could clear itself, resulting in a higher than allowable discharge rate.

CORRECTIVE ACTION:

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1. Change Notice 1299 was approved and issued. The Change Notice provided for the instanation of a bypass around the oil separator, to be uti-lized during a liquid waste release. Instanation was completed on Feb-ruary 8, 1981. This precludes the accumulation of contaminated water in the oil separator and eliminates the need to flush the oil separator following a liquid waste release.

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REPORTABLE OCCURRENCE 80-67 ISSUE 1 Page 5 of 7 CORRECTIVE ACTION: (Cont'd)

2. The liquid waste system operating procedure and associated surveillance requirement were revised to provide for the use of the oil separator bypass during a liquid taste release. The remaining dead leg in the liquid waste discharge system piping, approximately 150 gallons, is flushed with non-domestic clean water subsequent to liquid waste re-leases, at the recounsended liquid waste release rate.

No further cor metive action is anticipated or required.

FAILURE DATA /SIMILAR REPORTED OCCURRENCES:

None -

PROGRAMMATIC IMPACT:

None CODE IMPACT:

None I

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REPORTABLE OCCURRDICE 80-67 ISSUE 1 Page 7 of 7 Prepared By: dBtidh h.

Frederick J. Bors '

Senior Plant Eng.neer Reviewed By: M

. iff. aTim eennical Services Supervisor Reviewed By:

Frank M. Mathie Operations Manager Approved By:

Don Warembourg h W !% /'

Manager, Nuclear Production l

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ML19352B183

Text

Dear Mr. Seyfrit:

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