ML20101F101
| ML20101F101 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 06/15/1992 |
| From: | Eliason L NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9206240274 | |
| Download: ML20101F101 (5) | |
Text
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l Northem States Power Company 414 Nicohet Mall Minneapohs. M.nnesota $$4011927 Telephone (612) 330-5500 June 15,1992 10 CPR Part 2 Section 2.201 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, DC 20555 PRAIRIE ISI.AND NUCLEAR GENERATING PLANT s
Docket Mos. 50-282 License Nos. DPR 42 50 306 DPR 60 Reply to a No: ice of Violation NRC Inspection Report No. 306/92006 Inadequate Procedure for Draindown to Midloop Pursuant to the provisions of 10 CFR Part 2, Section 2.201, the following is cubtaltted in response to the notice of deviation contained i
,our letter of May 21, 1992.
Violatipa During an NRC inspection conducted from February 20 through March 30, 1992, a violation of NRC requirements was identifled.
In accordance with the "Cencral Statement of Policy and Procedure for NRC Enforcement Actions," 10 CFR Part 2, Appendix C (1992), the Nuc' e' - Regula Nry Commission proposes to impose a civil penalty pursuant to Section 234 of the Atoale Energy Act of 1954, as amended (Act), 42 U.S.C. 2282, and 13 CFR 2.205.
The particular violation and associated civil penalty are set forth below:
10 CFR 50, Appendix B, Criterion V states, in part, that activities affecting quality shall be prescribed by documented instructions, procedures, or drawings of a type appropriate tc the circumstances.
Contrary to the above, on February 6, 1992, the licensee f.s s ue d procedure D2, "RCS Reduced Inventory Operations," Rtvision 21, for draining the Reactor Coolant System (RCS), which was not of a type appropriate to the circumstances of its ute in that:
1.
The procedure did not specify an indicated Tygon tube reading of RCS level at which the operator was required to verify that the wide range Emergency Response Co:tputer System (ERCS) RCS level indication was functioning.
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Northern States Power Company June 15, 1992 Page 2 2.
The procedure did not provide adequate direction for controlling frequency for recording RCS level or RCS pressure RCS pressure, a readings, or a precaution indicating RCS pressure higher than about three psig would prevent the ERCS RCS level indicators from functioning.
3.
The procedure did no sp(cify any frequency for calculating holdup tank volture for comparison with the change in volume based on the change in RCS level indication and did not clearly specify a level to volume ratio to be used to calculate hoidup tank volume This is a Severity !.evel 111 eiolation (Lupplement 1.>
Civil Penalty - $12,500.
Respon<e to Violation Northern States Power Coapany, Prairie Island Nucl( ar Gene rat ing Plant admits to the violation and concurs with its content.
The Civil Penalty was paid by wire on May 29 1992.
Denton for the ViolLLinu The root cause of th= vio.ation is an over reliance on experienced engineers in the control room t o su >plenent a less than adequate written procedure for draining the Reactor ' col mt System.
The draining procedure was written and reviewed within the en; in sering organization at a level such that it could best be performed with 6e experienced engineers available for guidance, The engineers supporting the draindown in previous reiuelings were involved with the development of the procedures and thus were overly-f amiliar with the procedures and consequently assumed the three examples stated in the violation were common knowledge when in fact. they were not.
These same engineers had always been present during past draindown operations.
The concept of engineers supporting operations has been established with operations personnel starting at a very junior level.
The System Engineer concept at Prairie Island lends itself to direct support of operations.
During draindewn operations, shiit-personnel allowed the experienced engineers to become too involved in directing the operation.
In the recent refueling, these experienced engineers were replaced with less experienced engineers and a new procedure.
These situations caused the draindown incident.
Corrective Steps That Have P,een Taken qnd the R e s ul_t : Achieved Immediate corrective actions to resolve the procedure deficiencies were implemented prior to subsequent draining of the Reactor Coolant System during
Northern States Power Company g
June 15, 1992 Page 3 the refueling outage Changes to the draining procedure consisted of.
1.
Specifying a hold point at which to coupare the ERCS level indication with the Tygon tube level to assure operability of the ERCS level indication.
2.
Venting the Reactor Coolant Syst c m t o cont ainment atmosphere which precludes level errors associated with any overpressure. With this change it was no longer necessary to perform any level corrections.
Further, direction was provided for the frequency of recording Reactor Coolant System level readings to assure control of the draindown.
3.
Providing an accurate level-to volume ratio for the holdup.ank Frequency of drained volume cor.parison to Reactor Coolant System level was not necessary because there was no benchmark available with which to compare As an additional change to the draindown procedure the operations and engineering roles were specifically defined and dedicated shift manar,ement and experienced engineering personnel were assigned to the draindown.
After incorporating the actions identiiled above, tva draindowns of the b
Reactor Coolant System were successfully coupleted with no incidents.
Once the Reactor Coolant System draining was completed during the February,
/.
1992 refueling outage, all draindown procedures were removed irom the approved procedure list to assure comprehensive review and revision prior to next use.
Corrective Steps to be Taken te Avoid Furt her V1RLalions Prairie Island has performed a thorough review of the draindown incident and, as a result of the review, the following activities will take place to preclude overdraining the Reactor Coolant System in the future:
1.
All corrective actions tiat have been completed to date pertaining to procedure inadequacies will be incorporated in future revisions to the procedures as appropriate 2.
a nelf-limiting hot leg drain path will be provided on the Reactor Coolant System, with the piping routed to limit the Reactor Coolant System lower level to just below the top of the inside diameter of the hot leg during the draining process.
A vacuum breaker is being provided to assure no siphoning takes place.
3.
The location of the tap off of the Reactor Coolant Systcm used for shutdown purification will be changed to the Loop A pressurizer spray line.
This location is at the centerline of the cold leg which would limit any potential overdraining while in the shutdown
l Northern Sta%s Power Company USNRC June 15, 1992 Page 4 mode.
The resulting level. if problems were encountered.
1.*
adequate to support residual heat raaval pur p operat ion and prevent any significant vortexirg.
This path also provider remote I
isolation capabilities from the control room.
4.
A communication path between the Lo o-A hot leg and cold leg will be installed, to be used durirg the draindown.
This line will assure equalization of pressure across Loop A of the Reactor Coolant System.
A communication path presently, exists for Loop B.
The vent path on the reactor head will be enlarged to assure more timely pressure equalization of the reactor head volume with the Reactor Coolant System loop volume during the draining process.
6.
A non-intrusive Reactor Coolant System level inlicarion system will he installed.
This new system will be unaffected by the pressure in the Reactor Coolant System, thereby providing continuous level indication during any potential losu of shutdown events. This indication will only monitor lovel in the diameter of the loon piping and not the total Reactor Coolant System level.
7.
Nitrogen vill no lorcer be added to the Reactor Coolant System in the over-pressurizati>n mode, rather. It will be added directly to the steam generators via a drain path in the Reactor Coolant System intermediate loop.
With this change it will no longer be necessary to drain to the mid loop ele"ation.
8.
New procedures for reduced inventory operat!ans with the Reactor Coolant System intact will he developed to support the new hardware These procedures will be develooed from within the operations organization assuring the necessary operations inputs.
9.
Section Work Instruction, Sk l %, "inirequently Performed Operations", will be implemented in the development of the new draindown procedures.
This SWI provides management input to assure there is the appropriate balance of engineering support, operatiots management and training it further defines the scope ci the pre-task briefing and raic.es the in port ance of the task to the appropriate management level.
This SW1 will also be used to review the adequacy of all other critical evolution procedures.
10.
To the extent practicable, the new procedures will be validated on a simulator, assuring their usability.
11.
The operations organization will receive t'torough training on the new draindown procedures.
Other plant groups will receive training to the extent needed for each group.
The modifications to the primary systems are presently scheduled for
4 Northern States Power Ccmpany USNRC June 15, 1992 Page $
irnplernentation during each of the next two refueling outages for each unit.
1 Cornple tion of all activities identified c.bove will be achieved prior to the next planned entry into a reduced inventory condition, presently scheduled for Spring of 1994 Unit 1 and Winter of 1995 for Unit 2.
11 an unplanned entry into reduced inventory becorr.es necessary, the Reactor Coolant system would be drained using a new procedure which implettents the appropriate corrective actions as defined above or th core vill be unloaded.
Date When Full Cortoliance Vill Be Achirved_
Full cornpliance has been achievea.
Please contact us if you have any questfors or wish turther information concerning this rnatter.
e Leon. E ason Vice Present Nuclear Generation c:
Regional Administrator, Region 111, NRC Senior Resident inspector, Monticello Sit e, NRC NRR Project Manager, NRC J Silberg i
I
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