ML19347F143
| ML19347F143 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 04/29/1981 |
| From: | Varga S Office of Nuclear Reactor Regulation |
| To: | Dunn C DUQUESNE LIGHT CO. |
| References | |
| NUDOCS 8105150320 | |
| Download: ML19347F143 (3) | |
Text
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'o UNITED STATES
!%h(~g NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 j
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April 29, 1981
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r0, Docket No. 50-334 Mr. C. N. Dunn, Vice President t
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Operations Division Duquesne Light Company 435 Sixth Avenue Y
@p Pittsburgh, Pennsylvania 15219 c
Dear Mr. Dunn:
On February 29, 1980, we issued Amendment No. 26 to Facility Operating License No. DPR-66 which closed out the operability issue on containment purge and venting for Beaver Valley Power Station, Unit No.1.
However, our letter dated April 4,1980, expressed additional concerns about a potential problem with the electrical override or bypass of safety actuation signals. We have now completed our review of your subsequent submittals dated May 16, July.3, and August 7,1980 and it has been concluded that these electrical override / bypass concerns have been adequately addressed for your facility. Based on the above, it has been determined that the long term containment purge and vent requirements, as cur-rently defined, have been satisfied for Beaver Valley Power Station, Unit No.1.
However, the long-term review by the staff is continuing and a change in Technical Specifications (TS) may be required at a later date. You will be notified if any further action or a TS hange is required.
We have determined that additional modifications to ESF systems other than Containment Ventilation Isolation are necessary to provide appropriate physical features (e.g. key-lock switches) for manual override provisions and automatic system-level annunciation of the overridden status.
The interim measures taken by the licensee are sufficient to justify continued safe operation until the next refueling outage, at which time these modifications should be completed.
Additionally, your commitment, by letter dated February 23, 1981, to revise your procedures and conduct operator training to require operator action to manually cicse the feedwater isolation valves prior to using the associated reset features is a satisfactory interim measure to satisfy the staff concerns relating to over-ride of other engineering safety features actuation signals. Your commitment to complete, no later than the end of the next refteling outage, those electrical modifications necessary to prevent the automatic re-opening of these valves upon
" reset" is a satisfactory long term resolution of this concern.
G105150 W P
Mr. C. N. Dunn 2-A copy of our safety evaluation is enclosed for your information.
Please feel free to contact us if you have any questions or concerns.
Sincerely, l'N 1
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'[, /, hie teven rga Operating Reactors Br nch No. 1 Division of Licensi' g
Enclosure:
Safety Evaluation Report cc w/ enclosure:
See next page 6
6 i
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r Mr. C. N. Dunn Duquesne Light Compary s
cc: Gerald Charnoff, Esquire Mr. James A. Werling Jay E. Silberg, Esquire Plant Superintendent Shaw, Pittman, Potts and Trowbridge Beaver Valley Power Station
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1800 M Street, N.W.
P. O. Box 4 i
tlashington, D. C.
20036 Shippingport, Pennsylvania 15077 Karin Carter, Esquire Mr. John A. Levin Special Assistant Attorney General Public Utility Commission Bureau of Administrative Enforcement P. O. Box 3265 5th Floor, Executive House Harrisburs, Pennsylvania 17120 Harrisburg, Pennsylvania 17120 Mr. J. D. Sieber, Superintendent Mr. Roger Tapan of Licensing and Compliance Stone and Webster Ingineering Duquesne Lignt Company Corporation Post Office Sox 4 P. O. Box 2325 Shipping: ort, Pennsylvania 15077 Boston, Massachusetts 02107 Irwin A. Popowsky, Esquire Mr. F. Noon Office of Consumer Advocate R S D Center 1425 Strawberry Square Westinghouse Electric Corporation Harrisburg, Pennsylvania 17120 Euilding 7-303 Pittsburgh, Pennsylvania 15230 Mr. Charles E. Thomas, Esquire Thomas and Thoaas B. F. Jones Memorial Library 212 Locust Street 663 Franklin Avenue Box 999 Aliquippa, Pennsylvania 15001 Harrisburg, Pennsylvania 17108 Mr. John Carey, Director R2sident Inspector Nuclear Operations U. S. Nuclear Regulatory Commission Duquesne Light Company Port ??* ice Box 298 435 Sixth Avenue St ' f i n: port, Pennsylvania 15077 Pittsburgh, Pennsyl vania 15219
'ir. R. E. Ma rtin Duq 2esne Light Company 435 Sixth Avenue Pittsburgh, Pennsylvania 15219 Marvin Fein Utility Counsel City of Pittsburgh 313 City-County Building Pittsburgh, Pennsylvania 15219 9
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ENCLOSURE SAFETY EVALUATION REPORT BEAVER VALLEY UNIT 1 OVERRIDE OF CONTAINMENT PURGE ISOLATION AND OTHER ENGINEERED' SAFETY FEATURE ACTUATION SIGNALS Introduction i
i Instances have been reported at nuclear power plants where the intended automat'ic closure of the containment porge/ ventilation values during a postulated accident would not have occurred because the safety actuation signals were inadvertently overridden and/or Blocked, due to design deficiencies.
These instances were determined to constitute an Abnormal Occurrence (178-S). As a follow up action, NRR tssued a generic letter, requesting each licensee to take certain actions.
Evaluation The enclosed report was prepared for us by Franklin Research Center, as put of our technical assistance contract program. The report provides their technical evaluation of the conformance of the Beaver Valley 1 plant design ;o the HRt,cr'teria.
I The report concludes that the NRC criteria are not apolicable to the containment ventilation tsolation system at Beaver Valley Unit 1, because the purge and ventilation valves are required (by Technical Specifications) to be maintained closed when the reactor is above 200*F, in order to maintain a sub-atmospheric containment pressure. This sub-atmospheric pressure is maintained by a single 2-inch line, which exhausts to the waste gas system and is isolated by the Phase A Containment Isolation signal.
Regarding other Engineered Safety Features (ESF), the report concludes that these systems comply fully with three of the six NRC criteria, do not comply with two of the criteria, and certain systems deviate, in some technical details, from one criterion.
The two areas of non-conformance are:
(a) the manual override provisions do not incorprate sufficient physical features (e.g., key-lock switches) to facilitate adequate administrative control of their use, and (b) lack of _ annunciation of the overridden status of the affected safety systems.
The systems involved with these two items included Containment Isolation Phase A, Containment Isolation' Phase B, and Safety Injection. As an interim measure, the labels for the " reset" pushbuttons associated with the Solid State. Protection System have been replaced with new labels that indicate that the switches are actually " overrides." The new label plates are a distinct color. The reactor operators have received instruction regarding the consequences of asing these " overrides."
DUPE.
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2-The systems that deviate in some technical details from the criterion regarding automatic re-positioning of valves and dampers upon operation of the " reset" pushbattons are: control room ventilation isolation, main feedwater regolating valve controls, ECCS accumulator isola _ tion valve controls, and manual transfer of the ECCS to the Recirculation Mode. The control room venti-lation system ts isolated automatically either by high chlorine level or By Containment Isolation Phase "B" (CIB). The manual reset of control room isolation, as a separate single system, requires a separate act on the part of the operator subsequent to the clearing or overriding of Soth the high chlorine and CIB signals.
This deviation is acceptable, stnce the system meets the intent of our criteria, that is, that resetting the signal does not produce any inadvertent or undesired valve motion.
Upon " reset" (override) of the Safety Injection signal, all main feedwater control valves will re-open and return to their normal modulating positions.
Similarly upon " reset" (override) of the Feedwater Isolation Signal (i.e.,
" Reset Bypass Valves Blocked") all main feedwater bypass control valves will re-open and return to their normal modulating positions. The re-opening of these valves still leaves two isolation barriers against blowdown from the steam generator or frem the auxiliary feedwater system.
This is an acceptable level of protection. However, the re-opening of these valves leaves only a single isolation barrier against main feedwater flow into the steam generator if any of the feed pumps remain un-tripped (i.e., main feedwater pumos or condensate pumps) following a main steamline break. At this plant, the condensate pumps are not automatically tripped on Safety Injection or Feedwater Isolation. Since only a single isolation barrier exists in this case, we cannot agree with the contractor's recommendation and we conclude that the plant design must be improved.
The licensee has agreed (in nis letter of February 23,1981), as an intarim measure, to revise his procedures (and to train the operators accordingly) to require manual operator action to switch each feedwater main control valve and feedwater bypass control valve from automatic to manual control and to set the manual demand to "0% open" for both valves for all steam generators prior to using the " reset" features for either Safety Injection or Feedwater Isolation. The licensee has further agreed, as a long-term action, to complete those electrical modifications necessary to prevent.the automatic re-opening of these valves upon " reset."
These modifications are to be completed no later than the next refueling outage.
l For the ECCS accumulator isolation valves, the fact that the circuit breakers are " racked out" during reactor operation (by Technical Specification requirement) precludes any adverse impact from an overr de action by the control circuitry. Therefore, this deviation is acceptable.
For the transfer of the ECCS to the Recirculation Mode, the operator may use the system-level actuate features to effect this transfer. Upon such a manual. actuation all valves will go to completion. Upon such manual actuation, electrical contacts prevent a subsequent automatic actuation from trying to effect the same transfer. This deviation is acceptable, since it prevents the automatic system from interferring with the transfer sequence and since this feature will not adversely affect the transfer function.
Conclusion.
Based upon our review of Beaver Valley Unit 1 and upon our review of the contractor's technical report, we conclude that:
1.
The NRC criteria do not apply to the containment purge and ventilation system, at this plant.
2.
The licensee has agreed to make those modifications, at the next refueling, necessary to prevent the main feedwater control valves an'd the bypass feedwater control valves from automatically re-opening upon " reset" (i.e., override) of the Safety Injection or Feedwater Isolation signals.
3.
Additional modifications are necessary to ESF systems oi;her than Containment Ventilation Isolation (CVI) to provide:
a, Appropriate physical features (e.g., key-lock switches) for the manual override provisions.
b.
Automatic system-level annunciation of the overridden status, when an override is active.
We believe that the interim measures taken by the licensees are sufficient to justify continued safe operation until the next refueling outage, at wnich time these modifications should be completed.
I l
t TECHNICAL EVALUATION REPORT OVERRIDE AND RESET OF CONTROL CIRCulTRY IN THE VENTILATION / PURGE ISOLATION AND OTHER ENGINEERED SAFETY FEATURE SYSTEMS DUQUESNE LIGHT COMPANY BEAVER VALLEY UNIT 1 NRC DOCKET NO.
50-334 N RC TAC NO.
10473 FAC PROJECT C5257 6
NRC CONTRACT NO. NRC43-79-118 FRC TASK 182 Prepared by Franklin Research Center Author:
I. H. sargene ( 'sI)
The Parkway at Twentieth Street J. scene (nc)
Philadelphia, PA 19103 FRC Group Leader: J. scene Prepared for Nuclear Regulatory Commission Washington, D.C. 20555 Lead NRC Engineer:
J. T. Seard I
l January 20, 1981 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, I
makes any warranty, expressed or implied, or assumes any legal liability or resconsibility for any third party's use, or the results of such use. of any information, apparatus, product or process l
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