05000267/LER-1981-013, Forwards LER 81-013/01T-0.Detailed Event Analysis Submitted
| ML20003B743 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 02/17/1981 |
| From: | Warembourg D PUBLIC SERVICE CO. OF COLORADO |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| Shared Package | |
| ML20003B744 | List:
|
| References | |
| P-81056, NUDOCS 8102250427 | |
| Download: ML20003B743 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| 2671981013R00 - NRC Website | |
text
._
puhuc servlee company ce ceDonde p.
16805 ROAD 19%
PLATTEVILLE, COLORADO 80651 P
m*
February 17, 1981 Fort St. Vrain Unit No. 1 P-81056 Mr. Karl V. Seyfrit, Director Nuclear Regulatory Commission Region IV Office of Inspection and Enforcement 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76012
Reference:
Facility Operating License No. DPR-34 i
Docket No. 50-267
Dear Mr. Seyfrit:
Enclosed please find a copy of Reportable Occurrence Report No. 50-267/
81-013, Final, submitted per the requirements of Technical Specification AC 7. 5. 2 (a)2.
Also, please find enclosed one copy of che Licensee Event Report for Reportable Occurrence Report No. 50-267/81-013.
Very truly yours,
.j w/
Don Warembourg Manager, Nuclear Production DR/cis Enclosure N
cc: Director, MIPC 5
I(
f 8102250 g
REPORT DATE:
February 17, 1981 REPORTABLE OCCURRENCE 81-013 Determined ISSUE O OCCURRENCE DATE:
Februarv 3.1981 Page 1 of 7 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY RCAD 19 1/2 PLATIEVILLE, COLORADO 80651 REPORT NO. 50-267/81-013/01-T-0 Final IDENTIFICATION OF OCCURRENCE:
On Tuesday, February 3,1981, at 1115 hours0.0129 days <br />0.31 hours <br />0.00184 weeks <br />4.242575e-4 months <br />, it was determined that the con-centration of tritium in an unrestricted area following liquid waste release number 429, which was made on January 23 and 24,1981, exceeded the limit specified in LCO 4.8.2(a).
At the time of the occurrence, the reactor was operating at approximately 46% chermal power and 130 MR electrical.
This event is reportable per Fort St. Vrain Technical Specification AC 7.5.1(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 429, 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.
Ef ents from the reactor building sump (
) and the liquid waste system (
) are discharged to a common line (
) leading to the Goosequill Ditch D
).
Circulating water blowdown (
) is ad-mitted for dilution purposes prior to the effluent raaching the Goosequill Ditch. Radiation monitors RIS-6212 and RIS-6213 ( 1 and 2 ) in the com-mon discharge line alarm at preset values on high activity in effluent dis-charged from either the reactor building sump or the liquid waste system and provide a s al to crip the liquid waste transfer pumps ( (}) ), close HV-6212 (
, and if the release is from the reactor building sump, close HV-7204-2
), thus terminating the release.
61020"t
REPORTABLE OCCURRENCE 81-013 ISSUE O Page 2 of 7 DESCRIPTION OF OCCURRENCE:
(Cont'd)
Circulating water blowdown flow is monitored by flow switch FSL-4101 ( ([) )
and at a preset value of low blowdown flow provides a signal to close HV-6212 an to tri the liquid waste transfer pumps and reactor building sump pumps
(
)(
on Figure 1).
Under normal conditions, discharge from the reactor building sump (System 72) is at a flow rate less than or equal to 10 gpm. However, discharges at a rate in excess of 10 gpa (up to a maximum of approximately 50 gpm with one reactor building sump pump in service) can be made, provided the sump con-cents are previously analyzed to assure compliance ich LCO 4.8.2 and 4.8.3.
Flow rate is then increased by opening a bypass ( 8 ) in parallel with the radiation monitors. Under these conditions, a preportionate sample flow con-tinues to pass through the radiation monitors to provide a means for termi-nation of the release on high activity by closing HV-6212 and HV-7
- - 2 and directing the effluent to the liquid waste system via HV-7204-1 (
).
Releases from the. liquid waste system (System 62) are governed by the require-ments of Technical Specification LCO 4.8.2.
Prior to release, a maximum dis-charge rate is established based on radionuclide concentrations in the liquid wasta effluent. Based on the calculated release rate, it may be necessary to
~ increase the blowdown flow to greater than-the nominal 1100 gpm to provide
~
sufficient dilution to assure that radionuclides in concentrations greater than MPC are not released to unrestricted areas. It may also be necessary to change the trip setpoints of the radiation monitors or to reduce the al-
- - lowable release rate to assure that the discharge is within the specified li mits.
However, the design of tho'11q waste system did not take into account the effects of an oil separator (
) in the discharge line connon to the reactor building sump and liqui waste discharge system. 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 gallons. 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 up in the oil separator down-stream of the monitoring equipment.
f Furthermore, if 'a release from the reactor building sump were to be made fol-Llowing a liquid waste release at a ralease rate higher than that allowable for the liquid waste release,.the radioactive liquid which had been held up
~in the oil separator-would be released at an unacceptable release rate.
- - This higher release rate would result in a smaller' dilution factor than originally calculated for the. liquid ' waste release. This. reduced dilution could result in discharges to the' unrestricted area in excess of the allow-able radionuclide. concentrations contained in LCO 4.8.2(a).
REPORTABLE OCCURRENCE 81-013 ISSUE O i
Page 3 of 7 DESCRIPTION OF j
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 immedi-ately af ter terminating a liquid waste release.
(See corrective action #1 of R0 80-52.) The release rate from the sump is to be less than or equal to the release rate authorized for the liquid waste release. This procedure has been followed on liquid waste releases made subsequent to October 10.
In addition to che 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 waste release and for the entire duration of the reactor building sump release (see corrective action #2 of RO 80-52).
Liquid waste release number 429 was initiated at 1911 hours0.0221 days <br />0.531 hours <br />0.00316 weeks <br />7.271355e-4 months <br /> on January 23,
.i 1981. The recommended release rate was 3.0 gpm, with a cooling cover blow-1-
down (dilution) race of 2300 gpm.
Subsequent analysis indicated a calcu-laced average release rate of 1.5 gpm and a calculated average blowdown rate of 2548 gpm.- The 6000 gallon reactor building sump release was begun at 1920 hours0.0222 days <br />0.533 hours <br />0.00317 weeks <br />7.3056e-4 months <br /> on January 24, 1981, and secured at 0220 hours0.00255 days <br />0.0611 hours <br />3.637566e-4 weeks <br />8.371e-5 months <br /> on January 26, 1981. The reactor building sump flow race was adjusted by operations per-sonnel so thac the sump flow rate recorder, FR-7216, read approximately 3 gpm.
Health physics personnel collected liquid samples per the' Health Physics Order during the liquid waste release and on an hourly basis during the sub-sequent reactor building sump release. Analysis of the samples taken during the sample release indicated the following results:
Sample Date/ Time Sample Number 3H uCi/cc 1-23-81/1910 RC 17358 1.25E-4' 1-23-81/2010 RC 17359
- 2. 90E-3 1-23-81/2110 RC 17360 3.39E-3*
1-23-81/2210 RC 17361 3.29E-3*
1-23-81/2310 RC 17362
- 3. 5 7E-3*
1-24-81/0010 RC 17363 3.23E-3*
1-24-81/0111 RC 17364 1.48E-3 The results of ' subsequent samples indicated compliance with LCO 4.8.2(a).
- Results in excess of LCO 4.8.2(a) 3H limiting concentration in an unre-stricted area (3.0E-3 pC1/ce).
REPORTABLE OCCURRENCE 81-013 ISSUE O Page 4 of 7 DESCRIPTION OF OCCURRENCE:
(Cont'd)
It should be noted that the samples indicating a concentration of tritium exceeding the limit of LCO 4.8.2(a) were takea.Jrom the Goosequill Ditch, considered to be in the unrestricted area air, hough located on 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 with-in the limits of LCO 4.8.2(a).
APPARENT CAUSE OF OCCURRENCE:
The design of the Fort St. Vrain liquid waste discharge system was inade-quate to preclude problems of this nature from arising.
ANALYSIS OF 0CCURRENCE:
Deviation #80-445 to Surveillance Procedure Number SR 5.8.2be-M was written in October, 1980, 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 gallon flush of the oil separator in the dis-charge line common to the reactor building sump and liquid waste discharge systems,. following a radioactive liquid waste release, at a rate less than or equal to the recommended liquid waste release race.
Following liquid waste release number 429, operations personne' correctly followed the requirements of SR 5.8.2bc-M and left HV-6212 ( 4 ) 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 controller for HV-6212, HC-6212, lo-cated on the 4771' elevation of the Reactor Building, by hand, while a Re--
actor Operator in the Control Roon ebserved the flow rate meter TR-7216.
FR-7216 is a linear. flow rate recorder with a range of 0 - 123 gpm, incre-mented by 2.5 gpm. Accurate confirmation of a small (less than 5 gpm) re-lease rate using FR-7216 is not possible. An analysis of the FR-7216 re-corder subsequent to the occurrence confirmed that no useful information can be obtained for release rates less than 5 gpm.
FIQ-7216 indicated an hourly average flow rate from the sump of'1.2 gpm from 1910 to 2010 hours0.0233 days <br />0.558 hours <br />0.00332 weeks <br />7.64805e-4 months <br /> on Janu-ary 24, 1981, and an hourly average of 1.9 gpm from 2010 to 2110 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.02855e-4 months <br />. The fact that the results of the liquid sample taken at 2110 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.02855e-4 months <br /> on January 24, 1981, indicated a concentration of tritium in excess of LCO 4.8.2(a) limits, shows that spikes in reactor building sump flow rates existed in the early stages of the sump release. FR-7216 and FIQ-7216 are. inadequate to ensure a low (less than 5 gpm) release rate from the reactor building sump using the 50 gpm sump pumps. This inability to accurately establish the 3.0 gpm al-lowable release rate from the reactor building sump contributed to exceeding the limit of LCO 4.8.2(a).
I REPORTABLE OCCURRE' ICE 81-013 ISSUE O Page 5 of 7 CORRECTIVE ACTION:
- 1) Liquid waste releases from Fort St. Vrain were immediately suspended upon discovery of the occurrence. The suspension was effective until definitive corrective action was taken to prevent recurrence.
- 2) Change Notice 1299 was approved and issued. The Change Notice provides for the installation of a bypass around the oil separator to be utilized during a liquid waste release. Installation was completed on Febru-ary 8, 1981.
- 3) The liquid waste system operating procedure and associated surveillance requirement were revised to remove the 6000 gallon reactor building sump release and provide for the use of the oil separator bypass. The re-maining dead leg in the liquid waste discharge system piping, approxi-mately 150 gallons, is to be flushed with clean water subsequent to liquid waste releases, at the recommended liquid waste release rate.
No further corrective action is anticipated or required.
FAILURE DATA /SIMILAR REPORTED OCCURRENCES:
Reportable Occurrence 80-52 and Reportable Occurrence 80-67 deal with re-laced subject areas.
PROGRAMMATIC IMPACT:
None CODE IMPACT:
None
FIGil':E I Circulating Wate r Illowdown c-p I
L
_leS I.
- - -.{
1 1
FSL-101 50 gpm hypass h
a close on high.setivity M
,' or low blowdown flow 6212 6213
. IIV-6212 i
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- G v,
Coosequ 11 e
l l
l Ditch I- -,- - :
Cadioactive I.2 quid llaste (System 62) e e
a e
Proposed I.ocaLIon of s_----------s 011 Separator yg.,
My a llV-7204-2 hy
- ob o
Close On y
l~
r~ ~ 'l~~
1 7-
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liigh Activity N
e o
n P_.g.._L_____-
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IJOTE: For simplicity, only those components 8
ggy_7394 g referenced in this report have been Reactor lluilding., i,_ __
y included on this drawing. Actual m
Sump (System 72)
To 1.1<lu id valve positions will depend upon the f
e Waste System operation taking place, Trip on low blowdown flow
REPORTABLE OCCURRENCE 81-013 ISSUE O Page 7 of 7 d/Alclc N
Prepared By:
~
Fiederick J. B(1st Senior Plant Engineer Reviewed By:
J.W.Iphm J
Technical Services Supervisor i
Reviewed By:
dd)7((e.wd f["r Frank M. A this/ /
Operations Manager Approved By:.((@ b k-Don Wardsbourg' /
Manager, Nuclear Production