ML20106B611
| ML20106B611 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 01/24/1985 |
| From: | Lee O PUBLIC SERVICE CO. OF COLORADO |
| To: | Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| P-85022, TAC-59936, NUDOCS 8502110703 | |
| Download: ML20106B611 (5) | |
Text
.s PUBLIC SERVICE COMPANY OF COLORADO P.
O.80X 84O DENVER.
COLORADO 8020s OSCAR R. HE January 24, 1985 vic' " * '"'
Fort St. Vrain Unit No. 1 P-85022 3 @ M OWB fia Regional Administrator "g li Region IV i
Nuclear Regulatory Comission FEB-4885 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011
_y Attn: Mr. E. H. Johnson
SUBJECT:
Fort St. Vrain Improvement Comittee Actions
REFERENCE:
H. R. Denton to R. F. Walker October 16, 1984, Audit of Fort St. Vrain Operations
Dear Mr. Johnson:
The above referenced letter identifies the requirement that Public Service Company (PSC) must develop a plan to carry out modifications recommended by the PSC " Moisture Ingress Comittee" that are determined by PSC to have a high potential to significantly _ reduce the frequency and severity of plant upsets involving injection of circulator bearing water into the primary system. Response to this issue was further addressed in the January 15, 1985 PSC/NRC meeting held in Arlington, Texas.
Public Service Company fully recognizes the seriousness of the l
moisture ingress events that are all too repetitious in the operation of Fort St. Vrain. Our concern with this issue and other impediments to obtaining realisitic plant operation has-prompted Corporate management to form the Fort St. Vrain Improvement Committee which, under the chairmanship of Mr.
R.
F.
Walker, President and Chief Executive Officer, has as its general charter to evaluate innovative and substantial modifications at Fort St. Vrain which would have the benefit of improved availability. The membership cf this comittee F
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P-85022 Paga 2 is presently.made up of Officers and Division Managers directly associated with the Pa nuclear program. This comittee is augmented by outside organizations with strong ties to the nuclear power industry.
The resources and responsibilities of the new Fort St. Vrain Improvement Comittee encompass but extend beyond those of the Moisture Ingress Comittee.
Because of this, an initial action of the Fort St. Vrain Improvement Comittee was to review the substantial efforts, both completed and ongoing, of the Moisture Ingress Comittee and then disbanded it.
Many issues either have been or are being addressed by these comittees. Most of the issues require time consuming engineering analysis because of the complexities of the Fort St. Vrain Circulator Auxiliary System and many have been. evaluated and found to lack benefit and were rejected.
A sample tabulation of the issues addressed by the Fort St. Vrain Improvement Comittee and/or the Moisture Ingress Comitee which are either under consideration or have been found acceptable are included as an attachment to this letter.
These are divided into the following four categories:
Issues currently under consideration by the Fort St.
Vrain Improvement Committee Circulator Auxiliary System modifications yet to be completed prior to startup Circulator Auxiliary System modifications to be completed prior to startup provided material availability and schedule permits Items identified by the Moisture Ingress Comittee which are installed and operational Public Service Company is totally comitted to the dependable operation of Fort St. Vrain and intends to vigorously pursue plant improvements to obtain this goal.
Very truly yours,
- 0. R. Lee, Vice President Electric Production ORL/ HLB:pa Attachment l
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-Issu:s Currently.
Under
. Consideration by the Fort.St.
Vrain
-Improvement Committee Investigate the -possibility of: installing motor driven, i
magnetic bearing' circulators into. Fort St. Vrain.
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Investigate the possibility of installing motor driven,. oil-bearing. circulators-into Fort--St. Vrain.-
Investigate installation of' hydrostatic seals on the existing Fort St. Vrain circulators.
Investigate seals currently designed into the conceptual i
large HTGR circulators for application to the existing Fort St. Vrain circulators.
3 Investigate replacement of the main bearing water drain control valve with a fixed orifice.
4 Plug the lower helium / water drain ports on the existing Fort St. Vrain circulator housings.
i
~ Investigate removal of the trip inhibit for the second circulator in a coolant loop.
Evaluate the addition of a water slinger onto-the existing Fort St. Vrain circulator.
i Evaluate the addition of a helium / water drain forced scavenging jet pump on existing Fort St. Vrain circulator auxiliaries.
Evaluate the replacement of the. buffer helium recirculator.
with an eductor system on the existing Fort St. Vrain l
circulator auxiliaries.
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e Circulator.. Auxiliary System Modifications Yet to be Completed Prior to Startup Install new positioners on the high pressure separator drain valves.
Install additional computer inputs to monitor helium circulator auxiliary system parameters relatad to moisture ingress.
Modify the
,ch pressure separator level control system and separate it from the main drain controls.
Replace the bearing water PDIS cables with shielded cables.
Modify helium circulator and control rod drive helium purge supply lines to accept future moisture removal and monitoring equipment.
Modify the normal bearing water isolation valves to close on specific bearing water pump signals.
Although not a
plant-modification, a
moisture ingress / removal manual will be finalized for the operator's use prior to plant startup.
Circulator Auxiliary System Modifications to be Completed Prior to Start Up Provided Material Availability and Schedule Permits Install electronic controls on the main drain control system for all circulators.
Replace the existing main-drain valve on one helium circulator with a Digital valve.
This modification would then be evaluated prior to installation on the other circulators.
Replace the laminar flow elements on "D" circulator buffer supply and return with subsonic Venturi type elements. This modification would then be evaluated prior to installation on other helium circulators.
Replace the Barton level indicating system on the buffer
.recirculators with a system of higher reliability.
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i Items Id:ntified by the Moisture Ingress Comittee Which Are Installed and Operational Indicating lights have been installed in the Control. Room to show the operator when an accumulator has been fired.
A seal-in circuit was added to interlock the back-up bearing water -2 valves with the normal bearing water supply valve and to require reset action to open the supply valve.
Evaluation of the accumulator firing program has been completed and found to be satisfactory.
System 21 instrument calibration frequency has been evaluated and necessary modifications made to these procedures.
The size of the drain line from the high pressure separator has been increased to handle up to 20 gallons per minute flow rate.
The. drain line from the high pressure separator has been rerouted-into the top of the bearing water surge tank rather than into the main drain line.
The helium water drain line from the circulator to the high pressure separator has been modified to eliminate the-loop seal which previo'isly. existed.
A Transient Improvement Comittee has been established to investigate all serious plant transients and to recomend plant modifications which might eliminate future transients from similar conditions.
A computerized System 21 data acquisition system was developed and placed in service to permit better analysis of plant transients.
(This system is being expanded at the present time).
As an interim measure, valve opening boosters were installed on the existing main drain pneumatic valves.
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