ML20003B907
| ML20003B907 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 01/09/1981 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | BOSTON EDISON CO. |
| Shared Package | |
| ML20003B908 | List: |
| References | |
| NUDOCS 8102260099 | |
| Download: ML20003B907 (6) | |
Text
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'JNITED STATES OF AMERICA 7590-01 NUCLEAR REGULATORY COPNISSION In the Matter of
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BOSTON EDISON COW ANY Docket No. 50-293 (Pilgrim Nuclear Power Station,
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Unit No.1)
ORDER FOR MODIFICATION OF LICENSE I.
The Boston' Edison Company (licensee) is the holder of Facility Operating License No. DPR-35 which authorizes the operation of the Pilgrim Nuclear Power Station, Unit No.1, at steady state reactor pwer levels not in excess of 1998 megawatts thermal (rated power).
The f acility consists of a boiling water reactor located at the licensee's site near Plymouth, Massachusetts.
1 II.
l During a routine shutdown of Browns Ferry Unit No. 3 on June 28, l'980, 76 of 185 control rod., 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 B)R Control Rod Drive Systems which indentified design deficiencies requiring both short and long-tem corrective measures. These measures are set forth in the Generic Safety Evaluation Report - BWR SCRAM DISCHARGE SYSTEM, dated Decetter 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 8102260 @
l 7590-01 2-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 Discharge 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 i
an event of this generil type (but with no adverse consequences) actually occurred at the Quad Cities Unit 1 reactor on January 3,1977.
l IE Bulletin 80-17 (Supplement 3) requires an immediate manual scram when I
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 l
the r.ucher of control rods that ate at high temperature. Beginning on December 1,1980, protection was also provided by continuous monitoring of the SCV 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 This continuous monitoring system and operator response provide procedures.
important protection against water accumulation in the SDV headers under slow fill conditions; however it does not address completely all the potential loss of air events.
In addition, a human factors evaluation determined that reliance on the operator to successf'J11y carry out a manual scram within a limited time frame may not be assure.. Therefore', in the short term in order to provide prompt added protection for credible degraded air conditions in BWR control air supply systems, it is necessary that an automatic system be operable to initiate control rod insertion by rapidly dumping the control air system header if the air pressure decreases below a prescribed value.
The NRC staff is developing revised design and safety criteria for a lono term solution to. this problem.
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l III.
The Generic Safety Evaluation Report (SER) of December.1,1980, reconnended ths.t this automatic air header dump syster be installed within two months. As a result of questions as to whether a reli.able 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 We have also reevaluated the human factors involved
- our original estimate.
in carrying out the requirements of IE Bulletin 80-17 (Supplement 3) which requires a manual scram of the reat tor on alarms related to the loss of l t air pressure in the air system. These alams provide some added assurance l
that the operator can trip the reactor before the scram discharge volume i
fills.
h As a result of these analyses I have detamined that the pu ic 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 E
period does not present an undue risk to the public health and safety.
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I have further determined based on staff evaluations of installed air c
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systems, and on staff discussions with industry rept,eser.tatives that a 90-day period will allow adequate time for design, procurement, t -
fabrication, installation, and testing for an automatic.3ir dump system of the type prescribed in this Order.
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7590 01_.
' As discussed above, altheigh (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 I have (3) the criteria for a long term fix are currently being developed.
determined that the public health and safety require the additional measures prescribed by this Order and their inplementation on this short time schedule. However, in view of the immediacy of the need for this system, the system being ma'nda'ted by this Order is not being made subject to the requirements of Appendices A and B to 10 CFR Pact 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 No. DPR-35 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 irisertion 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; l
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/ygo ui 5-(el Any required power supply should not be subject to any failure mode which could also initiate the degraded-air conditions, unless it can be demonstrated that an automatic scram will occur promptly because of the failure mode of the pcwer supply; (f} The, systen is not subject to the requirements of Appendices A
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and 8 of 10 CFR 50; (c) 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 conr;1eted; and (1) The system shall be functionally tested at och Unit shutdown, but need not be tested more than once each 90 days.
(2) After April 9,1981, the Automatic Dump System as described above shall be operable in all modes other than shutdown 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, b
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TheItcenseeoranypersonwhosetherestsmaybeaffectedby.this
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Order may request a hearing within 20 days of the date of publication of 4
this Order in the Federal Register. Ary requ?.st for a hearing will not stay the effective date of this Order. Any request for a hearing shall be addmssed to the Director, Office of Nuclear Reactor Regulation, U. S.
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Nucle'ar Regulatory Commission Washington, D. c. 20555. A copy of the
. -request should also be sent to the Executive Legal Dimetor, U. S. Nuclear Regulatory Commission, Washington, D. C.
20555.
If a person other than 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.
i VI.
If a hearing is held concerning this Order, the issue to be considered at the hearing shall be:
Whether the licensee should be required to have the automatic p
system required by Sectica IV to be operable by April 9,1981.
Operation of the facility on terms consistent with this Crder is not stayed L
by the pendency of any proceedings on the Order.
R THE NUCLEAR CGULATORY COM4ISSION t
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N Darrell G.
ise. hut Director Division of Licensing-Office of Nuclear Reactor Regulation 8
53I Dated:
Bethesda, Maryland t
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