ML19341B210
| ML19341B210 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 01/09/1981 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| Shared Package | |
| ML19341B211 | List: |
| References | |
| NUDOCS 8101300453 | |
| Download: ML19341B210 (6) | |
Text
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UNITED STATES OF AMERICA O
NuttEAR RtGu'ATORv COMMISSION In the Matter of
)
)
PHILADELPHIA ELECTRIC COMPANY, E~ AL
)
Docket No. 50-277
)
(Peach Bottom Atomic Power Station,
)
Unit No. 2)
ORDER FOR MODIFICATION OF LICENSE l
1.
l Philadelphia Electric Company (licensee) and three other co-owners are the holders of Facility Operating License No. DPR-44, which authorizes the operation of the Peach Bottom Atomic Power Station, Unit No. 2, at steady state reactor power levels not in excess of 3293 megawatts thermal (rated power).
The facility consists of a boiling water reactor located' at the licensee's site in Peach Bottom, vork County, Pennsylvania.
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 I
from approximately 301, power. All rods were subsequently inserted within 15 minutes and no reactor damage or hazard to the public occurred. However, i
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 December 1,1980, prepred by the NRC staff. One of the deficiencies identified was a failure mode of'the control air system, which can conceivable cause an inability to scram 8101300450
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. 759001 the control rods.
Sustained low pressure in the control air system could result in complete or partial opening of multiple s' ram outlet valves before c
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 an event of this general type (but with no adverse consequences)' actually occurred at th'e Quad Cities Unit 1 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 (LRD) 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 reactor scram, a question remains as to the adequacy of equipment and precedures. This continuous monitoring system and operator response provide l
important protection against water accumulation in the SDV headers under slow fill conditions; however it does not address completely all the potential l
l loss of air events.
In addition, a human factors evaluation determined I
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 cond'itions r
in BWR control air supply systems, it is necessary that an automatic system 1
be operable to initiate control rod insertion by rapidly dumping the control air system header if the air pressure decreases below a prescribed value.
. Tne NRC staff is developing revised design and safety criteria for a inna term solution to this problem.
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III.
The Generic Safety Evaluation Report (SER) cf December.1,1980, recomended that this automatic air header dump system 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 raview 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 ir 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
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air pressure in the air system. These alarms provide some addad assurance that the operator can trip the reactor before the scram discharge volume fills.
As a result of these analyses I have determined that the public heal h, safety and interest require that the automatic air dump system be in operation within 90 days of the date of this Order ar.d that operation during this period does not present an undue risk to the public health and safety.
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I have further detemined based on staff evaluations of installed air systems, and on staff discussions with industry repr,esentatives that
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a 90-day period will allow adequate time for design, procuremen' t, j
fabrication, installation, and testing for an automatic. air dump system of the type prescribed in this Order.
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4 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 of the imediacy of the need for this system, the system being mandated b) 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 No. DPR-44 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; I
(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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f 590 01 5-(.el Any required power supply should not be subject to ary failure mode which could also initiate the degrad,ed-air conditions, unless it can be demonstrated that an automatic scram will occur proaptly because of the failure mode of the power supply; (f) The system is not subject to the requirements of Appendices A
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and B ok10 CFR 50;
(.g) There shall be a documented independent design review of the system; l
(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 each 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 shutdown 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.
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Y-Theilicensee or any person whose interests may be aff ted by,this Order may request a hearing within 20 days of the date of publication of this Order in the Federal Recister. Any request for a hearing will not
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l sta?.he effective date of this Order.
Any request for a hearing shall be
~
addressed to the Director, Office of Nuclear Reactor Regulation, U. S.
Nuch r Regulatory Comission, Washington, D. C.
20555. A copy of the 1.
request should also be sent to the Executive Legal Director, 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 ir,terest may be affected Lp this. Order.
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VI.
t If a, hearing is held concerning this Order, the issue to be considered at the hearing shall be:
h 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 l.
by the pendency of any proceedings on the Order.
F R THE NUCLEAR REGULATORY COMMISSION l..
I m
arre Ei erihu.,
1 rector Division of LMeensing-Office of Nuclear Reactor Regulation b
Dated: JMUMy s 19 3 ;
Bethesda, Maryland
UNITED STATES OF AMERICA y r 349 g
w-3 NUCLEAR REGULATORY C04 MISSION In the Matter of
)
PHILADELPHIA ELECTRIC COMPANY, ET AL Docket No. 50-278 (Peach Bottom Atorde Power Station,
)
Unit No. 3)
ORDER FOR MODIFICATION OF LICENSE I.
Philadelphia Electric Company (licensee) and three other co-owners are the holders of Facility Operating License No. DPR-56, which authorizes the operation of the Peach ~ Bottom Atomic Power Station, Unit No. 3, at steady state reactor power levels not in excess of 3293 megawatts the
'l (rated p ower).
The facility consists of a boiling water reactor loct-at the licensee's site in Peach Bottom, York County, Pennsylvania.
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. How' eve r, the event did cause an in-depth review of the current BWR Control Rod Drive Systens which indentified design deficiencies requiring both short and long-l l
term corrective measures. These neasures are set forth in the Generic Safety l
Evaluation Report - BWR 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 1
1 I
l
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 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 corrective action before scram capability is lost.
It appears that an event of this general type (but with no adverse consequencesf actually occurred
~
at th'e Quad Cities Unit 1 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 on Decerber 1,1980, protection was also provided by continuous monitoring of the SDV as required by IE Bulletin 80-17 (Supplement 1).
However, since only j
a short time could be available for the operator to successfully initiate a reactor scram, a question rema, ns as to the adequacy of equipment and procedures. This continuous monitoring system and operator response provide important protection agcinst water accumulation in the SDV headers under i
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 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 EhR 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.
Tne NRC staff is developing revised design and safety criteria for a inna term solution to. this problem.
7590 01_
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III.
The Generic Safety Evaluation Report (SER) of December.1,1980, recommended that this autcmatic air header dump system be installed within f
two months. As a result of ouestions as to whether a relf.able system could be installed within two months, the staff continued to review this require-ment. We have performed a more detailed risk a:sessment whf ch has shown a I
lower probability for the loss of scram capability due to a loss of air than I
our original estimate. We have also reevaluated the human factors involved I
in carrying out the requirements of IE Bulletin 80-17 (Supplement 3) which i
requires a manual scram of the reactor on alarms related tc the loss of i
air pressure in the air system. These alarms provide some added assurance r-that the operator can trip the reactor before the scram discharge volume fills.
As a result of these analyses I have deterrined that the public health, h._..
safety and interest require that the automatic air dump system be in operation I
within 90 days of the date of this Order and that operation during this H.._.
1" period does not present an undue risk to the public health and safety.
l I have further detennined based on staff evaluations of installed air systems, and on staff discussions with industry repr,elentatives 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 system of the type prescribed in this Order.
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4 3_1 As discussed above, although (1) the fail. e 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 inplementaticn on this short time schedale.
However, in view of the imediacy of the need for this system, the :ystem being mandated by thi's 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 No. DPR-56 is hereby amended to add the following provisions:
l (1)
An automatic system shall be operable to initiate control rod insertion
\\
I on low pressure in the control air header, which meets the following l
criteria:
l (a) The system shall automatically initiate control od insertion at l
l 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;
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7590 01 5-(.el Any required power supply should not be subject to any i
l failure mode which could also initiate the degrad,ed-air conditions, unless it can be demonstrated that an automatic scram will occur promptly because of the failure mode of the power supply;
(.f) The, system is not subject to the requirements of Appeitdices A andBob10IFR50; (g) There shall be a documented independent design review of the system; l
l (h) Before the system is declared operable, a documented pre-operational test of the system will be successfully completed; and (1) The' system shall be functionally tested at each Unit sh'utdown, but need not be tested more than once each 90 days.
l (2) After April 9,1981, the Automatic Dump System as described above shall l
be operable in all modes other than shutdown and refueling or the unit l
shall be placed in a cold shutdown 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.
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The licensee 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 Order in the Federal Re;1 ster. Any request for a hearing will not stay the effective date of this Order.
Any request for a hearing shall be
~
addressed to the Director, Office of Nuclear Reactor Regulation, U. S.
l Nucle'ar Regulatory Comission, ashingten, D. C.
20555. A copy of the request should also be sent to the Executive Legal Director U. S. Nuclear I
Regulatory Comission, Washington, D. C.
20555.
If a person other tha$
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the licensee requests.a hearing, that person shall set forth with particularity the nature of their interest and the manner in which such e
interest may be affected by this. Order.
t l
VI.
If a hearing is held concerning this Grder, the issue to be considered at the hearing shall be:
Whether the licensee should be required to have the automatic r,
system re;uired by Section IV to be operable by April 9,1981.
Operation of the facility on terms cm,% tent with this Order is not stayed by the pendency of any proceedings on the Order.
FOR THE NUCLEAR REGULATORY COMMISSION h,
Darrell G. Ettenhut, Director Division of Licensing Office of Nuclear Reactor Regulation JMUARY !
1331 Dated:
Sethesda, Maryland
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