IR 05000267/1986017
| ML20238E070 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 09/03/1987 |
| From: | Heitner K Office of Nuclear Reactor Regulation |
| To: | Robert Williams PUBLIC SERVICE CO. OF COLORADO |
| References | |
| TAC-61491, NUDOCS 8709140116 | |
| Download: ML20238E070 (5) | |
Text
September 3,1987
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Docket No. 50-267~
Mr. R. O. Williams, Jr.
Vice President, Nuclear _ Operations Public Service. Company of Colorado P. O. Box 840 Denver, Colorado 80201-0840
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Dear Mr. Williams:
SUBJECT:
FORT ST. VRAIN LICENSEE EVENT REPORT 86-017 (TAC NO. 61491)
We are continuing to follow the events reported by you in Licensee Event Report (LER) No. 50-267/86-017 and your status report submitted on December 19, 1986 (P-86669).
Enclosure 1 is a request for additional information based on a review of these documents, by the staff and our contractor, Idaho National Engineering Laboratory (INEL).
We concur with INEL's finding that resolution of the problems raised by this-LER is not complete In order to provide a basis for finding that PSC has thoroughly addrested this LER, you should provide the additional information requested within 60 days of the date of this letter.
The information requested in this letter affects fewer than 10 respondents; therefore, OMB clearance in not required under P.L.96-511.
Sincerely, Id Kenneth L. Heitner, Project Manager Project Directorate - IV Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Regulation Reactor Enclosure:
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Docket 1No.'.50-267
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Mr.. R., Jr.
Vice President,' Nuclear Operations
'Public Service Company of Colorado
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'P. O. Box-840
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Denver,. Colorado 80201-0840
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Dear Mr. Williams:
SUBJECT:
FORT ST.'VRAIN LICENSEE EVENT REPORT 86-017'(TAC N0'. 61491)
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We.are continuing to follow the events reported by you in Licensee Event
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Report (LER) No. 50-267/86-017 and your status report submitted on December 19,
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(1986'(P-86669).
Enclosure 1 is a brief summary of our review of these documents, prepared by our contractor, Idaho National Engineering Laboratory'
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(INEL). ' Included'in'.this summary is a request for additional information.
We concur'with.INEL's finding that resolution.of the problems raised by this
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LER'is not complete.
In' order.to provide a basis for finding that PSC has thoroughly addressed this LER, you should provide the additional'information requested within 60 days of the date of this letter.
The information requested in this letter affects fewer than.10 respondents;
.therefore, OMB clearance ~in not required under P.L.96-511.
Sincerely, Kenneth~L.'Heitner, Program Manager Project Directorate - IV Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Regulation Reactor Enclosure:
.As stated
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cc w/ enclosure:
See=next page
- DISTRIBUTION '
Docket File NRC PDR Local PDR K. Heitner OGC-Bethesda E.~ Jordan PD4 Reading J. Partlow D. Crutchfield ACRS (10)
F. Schroeder 'PD4 Plant File P.'Noonan J. Calvo K. Heitner PD-b PD-4 $ f(
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Mr. R.,
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Public Service Company of Colorado Fort St. Vrain
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cc:
Mr. D. W. Warembourg, Manager Albert J. Hazle, Director Nuclear Engineering Division Radiation Control Division Public Service Company Department of Health of Colorado 4210 East lith Avenue P. O. Box 840 Denver, Colorado 80220 Denver, Colorado 80201 Mr. David Alberstein, 14/159A Mr. R. O. Williams, Acting Manager GA Technologies, Inc.
Nuclear Production Division Post Office Box 85608 Public Service Company of Colorado San Diego, California 92138 16805 Weld County Road 19-1/2 Platteville, Colorado 80651 Mr. H. L. Brey, Manager Nuclear Licensing and Fuel Division Mr. P. F. Tomlinson,. Manager public Service Company of Colorado Quality Assurance Division
. O. Box 840 Public Service Company of Colorado
,enver, Colorado 80201 16805 Weld County Road 19-1/2 Platteville, Colorado 80651 Senior Resident Inspector U.S. Nuclear Regulatory. Commission Mr. R. F. Walker P. 0. Box 840 Public Service Company of Colorado Platteville, Colorado 80651 Post Office Box 840
Denver, Colorado 80201-0840 d
Kelley, Stansfield & 0'Donnell Public Service Company Building Commitment Control Program Room 900 Coordinator 550 15th Street Public Service Company of Colorado Denver, Colorado 80202 2420 W. 26th Ave. Suite 100-0 Denver, Colorado 80211 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 l
Chairman, Board of County Commissioners of Weld County, Colorado
.Greeley, Colorado 80631 Regional Representative Radiation Programs Environmental Protection Agency 1 Denver Place 999 18th Street, Suite 1300 Denver, Colorado 80202-2413
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' ENCLOSURE 1
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FORT ST. VRAIN LER 50-267/86-017
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CORRECTIVE ACTIONS FOR SEVERE SNOWSTORM
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o REFERENCES:
(1) ' Letter, Public Service Company of Colorado (J. W. Gahm) to NRC, " Licensee
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' Event Report 86-017, Final Report," May 3, 1986, P-86349
(2)
Letter, NRC (K. L. Heitner) to Public' Service Company of Colorado (R. O. Williams, Jr. ),. " Fort St.. Vrain - Licensee Event. Report 86-017,"
September 26,.1986
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Letter, Public Service Company of Colorado (J. W. Gahm) to NRC (H. N. Berkow), " Status Report on LER 50-267/86-017," December 19,'1986, i
P-86669
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DISCUSSION AND REQUEST FOR ADDITIONAL-INFORMATION:
. Reference 1 provided the Licensee Event Report that described systems inter-actions that resulted from an unusually severe snowstorm.
Reference 2 provided'
a preliminary evaluation report on'the event and subsequent follow-up actions.
Reference'3 responded to the concerns raised by Reference 2 and provided additional'information on the event.
We have reviewed Reference 1 in concert with Reference 3 and have the following concerns:regarding the proposed changes.
(1) The statements such as " corrective actions have been' proposed," and "the susceptibility of these circuits to voltage transients has been considered for implementation during the next refueling shutdown", need further clari-
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fication.
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(2) Why is the bearing pump trip by the undervoltage relays prohibited below the 25% power level? The incident in Reference 1 occurred when the plant
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was operating at approximately 25% power.
No justification or analysis i
was provided in Reference 3 for bypassing the undervoltage trip below 25%
reactor power.
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(3) Both primary and back-up pumps are electric motor driven and supplied by the same source of AC power, and hence are equally affected by a severe f
electrical perturbation.
Both. automatic and manual start of the back-up i
pumps should ensure adequate bus voltage before starting the pumps.
L-Address _each of the following proposed corrective actions with reference to the
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above concerns and provide a schedule for the proposed evaluation and implemen-
.tation of the modifications with the necessary technical specification changes.
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Also provide a schedule for modifying procedures to incorporate any changes per IB, 10, and 1F.
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(1.
Be'aring water pump control circuit modifications.-
J Reference 3 states that corrective actions have been proposed. This includes:
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(A). Repla'ce existing undervoltage relays with high speed, adjustable setpoint relays.
L(B) Regular calibration of the replacement relays.
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-(C)' Addition of a prohibit circuit with the undervoltage relays to eliminate the trip (due to undervoltage) of the bearing water pump breaker when below 25% power.
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(D) Add administrative controls to ensure that the back-up bearing water pump circuit -(this is distinct from the back-up water pump system) is enabled upon reaching'25% power.
(E) Provide logic to close the bearing water supply valves when 480V bus 1 or 3 power is interrupted.
(F) Provide written operat'ing procedures for coping with severe electrical storms.
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2.
Helium purification system valve control circuit.
(A) The valve closure actuation signals were to be functionally tested and calibrated prior to power operation. Was this accomplished?
Address the need for this action to be performed regularly either through technical specifications or by using some other method of control.
(B) A commitment was made to investigate the susceptibility of the high temperature and high differential pressure current loops (in the control circuit) to voltage transients.
Has this investigation been completed? What are the results? Describe any circuit modifications and how it reduces the susceptibility to the voltage transients.
3.
Reference 1, in the " Safety Analysis" section, states that an in-depth review of the storm's effect on the reliability and the proper operation of the overall electrical grid (transmission system) and equipment (distribution system) would be conducted.
Provide the results of this review and describe any modifications that have occurred as a result of the review.
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