ML20003B543
| ML20003B543 | |
| 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 8102120377 | |
| Download: ML20003B543 (6) | |
Text
_
O UNITED STATES OF AMERICA 590 u NUCLEAR REGULATORY COMMISSION In the Matter of
)
)
COMMONWEALTH EDISON COMPANY AND
)
Docket No. 50-265 IOWA-ILLINOIS GAS & ELECTRIC COMPANY
)
(Quad Cities Nuclear Power Station.
)
Unit No. 2)
ORDER FOR MODIFICATION OF LICENSE I.
The Coninonwealth Edison Conpany,et al (licensee) is the holder of Facility Operating License No. DPR-30 which authorizes the operation of the Quad Cities Nuclear Power Station, Unit No. 2, 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 lice ~nsee's site near Cordova, Illinois.
II.
During 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 requiring both short and long-term corrective measures.
These measures are set forth in the Generic Safety Evaluation Report - BWR SCRAM DISCHARGE SYSTEM, dated Decenber 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 l
sion no 37 l
73 b.
the control rods. Sustained low pressure in the control air system could result in complete or partial opening of multiple scram outlet valves before opening' of the scram inlet valves, causing the Scram Discharge Volume (SDV) to fill rapidly, thus leaving a relatively short time for the operator to take ccrrective action before scram capability is lost.
It appears that an event of this g'eneral type (but with no adverse consequences) actually occurred at th'e Quad Cities Unit I reactor on January 3,1977.
IE Bulletin 80-17 (Supplement 3) requires an immediate manual scram when low 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 en 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 reactor scram, a question remains as to the adequacy of equipment and procedures. This continuous monitoring system and operator response provide l
l important protection againe' water accumulation in the SDV headers under
, low fill conditions; howe it does not address completely all the potential I
loss of air events.
In addi, 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 order to provide prompt added protection for credible degraded air conditions in SWR control air supply syster.s, it is necessary that an automatic system be operable to initiate control rod insertion by rapidly dumping the control 1
l air system header if the air pressure decreases below a prescribed value.
The NRC staff is developing revised design and safety criteria for a inne term solut'en to this problem.
m e
7590-01 -
III.
The Generic Safety Evaluation Report (SER) of December.1,1980, recemended that this automatic air header dump system be installed within two months. As a result of questions 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 lower probability for the loss of scram capability due to a loss of 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 alams provide some added assurance that the operator can trip the reactor before the scram discharge volume
.. -.... filis.
As a result of these analyses I have determined that the public health, safety and interest require that the automatic air dump system be in operation within 90 days of the date of this Order and that operation during this I
period does not present an undue risk to the public health and safety.
~
i have further detemined based on staff evaluations of installed air
~
systems, and on staff discussions with industry rep {es'entatives that
~
a 90-day period will allow adequate time for design, procurement, fabrication, installation, and testing for an automatic. air dump system of the type prescribed in this Order.
M g
- _y_,
. 75 5_
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 determined that the public health and safety require the additional measures prescribed by this Order and their implementation on this short time s chedule.
However, in view cf the immediacy 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 161i, and the Commission's rules and regulations in 10 CFR Parts 2 and 50, IT IS ORDERED THAT EFFECTIVE IMMEDIATELY, Facility Operating License No. OPR-30 is hereby amended to add the following provisions:
(1)
An automatic system shall be operable to initiate control rod insertion on low pressure in the control air header, which meets the following criteria:
(a) The system shall automatically initiate control rod insertion at 10 psi or greater above scram outlet valve opening pressure; (b) The system shall not degrade the existing safety systems (e.g.,
(c) The system shall allow for scram reset; (d) The design shall consider the potential for inadvertent or unnecessary scrams; i
f
1 7590 01, 5-(el Any required p:wer supply should not be subject to any failure mode which could also initiate the degrad,ed-air conditions, unless it can be demonstrated that an autorratic scram will occur prc=ptly because of the failun mode of the l
power supply; (f) The system is not subject to the requirerants of Appendices A and E 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 successfully completed; and (i) The, system shall be functionally tested at ear.h Unit shutdown, but need not be tested more than once each 90 days.
l l
(2) After April 9,1981, the Automatic Dump System as described above shall be operable in all modes other than shutdcrn and refueling or the unit shall be placed in a cold sliutdown condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> unless system operability is restored.
e I
~
.-.....,,.n.~. -
,.o i V.
The licensee or any person whose interests my be aff ted by this Order may request a hearing within 20 days of the date of publication of this Order in the Fe's.al Rectster. Any request for a hearing will not
~
stay the effective date of this Order.
Any request for a hearing shall be t
addressed to the Director, Office of Nuclear Reactor Regulation,U. S.
~'
Nucle'ar Regulatory Corr;::ission, Washington, D. C.
20555. A copy of the
~ ~ ~
request should also be sent to the Executive Legal Director, U. S. Nuclear If a person other thaN Regulatory Commission, Washington, D. C.
20555.
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 at the hearing shall be:
l Whether the licensee should be required to have the automatic system required by Section IV to be operable by April 9,1981.
Operation of the facility on terms consistent with this Order is not stayed by the pendency of any proceedings on the Order.
FOR THE NUCLEAh REGULATORY COMMISSION 1*
y h, hut Direct.or I
Z rre
. gsen i
Divisien of Licensing-Office of Nuclear Reacter Regulation ct gd. JMRY S
'351 5ethesda, Maryland i