ML20003B536
| ML20003B536 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities  |
| Issue date: | 01/09/1981 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML20003B528 | List: |
| References | |
| NUDOCS 8102120362 | |
| Download: ML20003B536 (6) | |
Text
i 7590 01_
h UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of
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COMMONWEALTH EDISON COMPANY AND
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Docket No. 50-254 IL'A-ILLINOIS GAS & ELECTRIC COMPANY
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(Quad Cities Nuclear Power Station,
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Unit No. 1)
ORDER FOR MODIFICATION OF LICENSE I.
The Comonwealth Edison Conpany,et al (licensee) is the holder of Facility Operating License No. DPR-29 which authorizes the operation of the Quad Cities Nuclear Power Station, Unit No.1, at steady state reactor power levels not in excess of 2511 megawatts thermal (rated power). The f acility consists.of a boiling water reactor located at the licensee's site near Cordova, Illinois.
II.
Ouring a routine shutdown of Browns Ferry Unit No. 3 on June 28, 1980, 76 of 185 control rods failed to fully insert in response to a manual scram from approximately 30% power. All rods were subsequently inserted within 15 minutes and no reactor damage or hazard to the public occurred. However, the event did cause an in-depth review of the current BWR Control Rod Drive Systems which indentified design deficiencies requ' ring both short and long-term corrective measures. These measures are set forth in the Generic Safety Evaluation Report - SWR SCRAM DISCHARGE SYSTEM, dated December 1,1980, prepared by the NRC staff. One of the deficiencies identified was a failure mode of the control air system, which can conceivably cause an inability to scram 8102120 V
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7590-01_ the control rods.
Sustained low pressure in the control air system could result in complete or partial opening of multiple scram outlet valves befort opening of the scram inlet valves, causing the Scram Discharga Volume (SDV) to fill rapidly, thus leaving a relatively short time for the operator to take corrective action before scram capability is lost.
It appears that an event of this cieneral type (but with no adverse consequencesi actually occurred at th'e Quad Cities Unit i reactor en January 3,1977.
IE Bulletin 80-17 (Supplement 3) requires an immediate manual scram when icw pressure occurs in the Control Rod Drive (CRD) air system or when other indications occur, such as multiple rod drift alarms or a marked change in the number of control rods that are at high temperature.
Beginning on December 1,1980, protection was also provided by continuous monitoring of the SDV as required by IE Bulletin 80-17 (Supplement 1). However, since only a short time could be available for the operator to successfully initiate a reac'er scram, a question remains as to the adequacy of equipment and p m cedures. This continuous monitoring system and operator response provide im;;rtant protection against water accumulation in the SDV headers under slew fill conditions; however it does not address completely all the potential t
loss of air events.
In addition, a human factors evaluation detennined that reliance on the operator to successfully carry out a manual scram within a limited time frame may not be assured. Therefore, in the short term in l
order to provide prompt added protection for credible degraded air conditions in Bh"A control air supply systems, it is necessary that an automatic system be operable to initiate control red insertion by rapidly dumping the control air system header if the air pressure decreases below a prescribed value.
. The NRC scaff is developing revised design and safety criteria for a lona term i
solution to this problem.
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7590 01 III.
The Generic Safety Evaluation Report (SER) of December.1,1980, recommended that this automatte air header dump system be installed within two months. As a result of questio'ns as to whether a reliable system could be installed within two months, the staff continued to review this require-ment. We have performed a more detailed risk assessment which has shown a 1cwer probability for the loss of scram capability due to a loss af air than our original estimate. We have also reevaluated the human factors involved in carrying ~ out the requirements of IE Bulletin 80-17 (Supplement 3) which requires a manual scram of the reactor on alarms related to the loss of air pressure in the air system. These alanns provide some added assurance that the operator can trip the reactor before the scram discharge volume fills.
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As a result of these analyses I have determined that the public health, I h..
safety and interest require that the automatic air dump system be in operation l ^
within 90 days of the date of this Order and that operation during this period does not present an undue risk to the public healt'. and safety, i have further determined based on staff evaluations of installed air systems, and on staff discussions with industry repr,e's'entatives that a 90-day period will allow adequate time for design, procurement,
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fabrication, installation, and testing for an automatic air dump
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i system of the type prescribed in this Order.
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7590-0 As discussed above, although (1) the failure of the control air system is a low probability event, (2) the actions already required provide a significant measure of assurance that such an event will not occur and (3) the criteria for a long term fix are currently being developed, I have detemined that the public health and safety require the additional measures pre' scribed by this Order and their implementation on this short time s chedule.
However, in view of the imediacy of the need for this system, the system being mandated by this Order is not being made subject to the requirements of Appendices A and B to 10 CFR Part 50.
IV.
Accordingly, pursuant to the Atomic Energy Act of 1954, as amended, including Sections 103 and 1611, and the Comission's rules and regulations in 10 CFR Parts 2 and 50 IT IS ORDERED THAT EFFECTIVE IMMEDIATELY, Facility Operating License fio. DPR-29 is hereby amended to add the following p rovisions:
(1)
An automatic system shall be operable to initiate control rod insertion on low pressure in the control air i.Gder, which meets the following criteria:
(a) The system shall automatically initiate control rod insertion at l
10 psi or greater above scram outlet valve opening pressure; (b) The system shall not degrade the existing safety systems (e.g.,
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(c)
The system shall allow for scram reset; (d)
The design shall consider the potential for inadvertent or unnecessary scrams; l
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(.el Any required p:wer supply should not be subject to any failure mcde which could also initiate the degraded-air conditions, unless it can be demonstrated that an automatic scram will occur promptly because of the failu a mode of the power supply;
(,f) The system is not subject to the requirements of Appendices A and B of'10 CFR 50; (g)
There shall be a documented independent design review of the system; (h)
Before the system is declared operable, a documented pre-operational test of the system will be sue:essfully completed; and (i) The, system shall be functionally tested at each Unit shutdown, but need not be tested more than once each 90 days.
(2) After April 9,1981, the Autcmatic Dump System as described above shall be operable in all modes other than shutdown and refueling or the unit l
l shall be placed in a cold sfiutdown condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> unless l
system operability is restored.
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7590'01 6-Y.
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Th'e Itcensee or any person whose interests may be affected by. this Order may request a hearing within 20 days of the date of publication of this 3rder in the Federal Register. Any request for a hearing will not
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stay the effective date of this Order.
Any request for a haaying shall be
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addressed to the Director, Office of Nuclear Reactor Regulation. U. S.
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Nucle'ar Regulatory Cort: ission, Washington, D. C.
20555. A copy of the request should also be sent to the E.xecutive Legal Director, U. S. Nuclear Regulatory Commission, Washington, D. C.
20555.
If a person other tha$
the licensee requests.a hearing, that person shall set forth with particularity the nature of their interest and the manner in which such interest may be affected by this. Order.
l VI.
If a hearing is held concerning this Order, the issue to be considered I
at the hearing shall be:
Whether the licensee should be required to have the automatic j.
system required by Section IV to be operable by April 9,1981.
Operation of the facility on terms consistent with this Order is not staved l
by the pendency of any proceedings en the Order.
s R THE NUCLEAR ~GULATORY COMMISSION
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DarrepG.lse.. hut, Director
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Division of icensing 1
Office of Nuclear Reactor Regulation
- 8 I53I Dated:
l 5etnesda, Maryland