ML19207B079
| ML19207B079 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 08/08/1979 |
| From: | Mattson R Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19207B080 | List: |
| References | |
| TAC-11431, NUDOCS 7908230352 | |
| Download: ML19207B079 (10) | |
Text
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of
)
)
DUQUESNE LIGHT COMPANY
)
OHIO EDIS0N COMPANY
) Docket No. 50-334 PENNSYLVAtlIA POWER COMPANY
)
)
(Beaver Valley Power Station, Unit No.1)
)
ORDER I.
The Duquesne Light Company, Ohio Edison Company, and Pennsylvania Power Company (the licensee) are the holders of Facility Operating License No. DPR-66, which authorizes operation of the Beaver Valley Power Station, Unit No.1 (the f acility) at power levels up to 2652 megawatts thermal (ratid power). The facility, which is locater at the licensee's site in Beaver County, Pennsylvania, is a pressurized water reactor used for the commercial generation of electricity.
II.
Because certain safety-related piping systems at the facility had been designed and analyzed with a computer code which sunned earthquake loads algebraically, the potential existed for compromising the basic defense-in-depth provided by redundant safety systems in the event of an earthquake. This is due to the fact that the technique of algebraic summation can be non-conservative. The safety implications of ' algebraic summation resulted from the possibility that an eartaquake, of the type for which plants must be designed, could cause a raattor coolant system pipe 79082303 @i
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. rupture as well as degrade the emergency core cooling system and other systems designed to mitigate such an accident. Therefore, by Order of the Director
' of Nuclear Reactor Regulation (the Director) for the Nuclear Regulatory Commission (NRC), dated March 13,1979 (44 FR 16511, March 19,1979),
the licensee was ordered to show cause:
1.
Why the licensee should not reanalyze the facility piping systems for seismic loads on all potentially affected safety systems using an appropriate piping analysis computer code which does not combine loads algebraicaily; 2.
Why the licensee should not make any modifications to the facility piping systems indicated by such reanalysis to be necessary; and 3.
Why facility operation should not be suspended pending such reanalysis and completion of any required modifications.
In view of the importance to safety of this matter, the Order was made immediately effective and the facility was required to be placed in the cold shutdown condition and remain in that mode until further Order of the Commission.
III.
The facility is currently in the cold shutdown condition. Pursuant to the March 13, 1979 Order, the licensee filed a written answer to
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. the Order by letter dated March 31, 1979.
In that response the licensee stated that it was reanalyzing all potentially affected safety systems
.for seismic loads using an appropriate method which does not sum loads algebraically.
By ietter dated June 19, 1979, the licensee submitted a document entitled,
" Report on the Reanalysis of Safety-Related Piping Systems for Beaver Valley No. 1 Unit," dated June 15, 1979.
Revisions to this report were submitted In their letters, the licensee by letters dated July 11,18, and 27,1979.
requested that the Commission's March 13, 1979 Order, which requires the plant to remain in a shutdown condition, be modified to permit operation of the unit for a period of six to seven weeks at which time the plant would be shut down for refueling. This request is based on the licensee's finding acceptable results of the ra.nclysis of the safety-related piping and supports (except as described below) for the Design Basis Earthquake (DBE) loading condition and on their commitment to: (1) shut down the facility if a seismic event occurs which results in accelerations greater than an acceleration level of 0.01 g, the setpoint of the facility accelerometers, and (2) inspect those piping systems and supports wnich have not veen shown to be fully acceptable for the Operating Basis Earthquake (OBE) case (ground acceleration of 0.06 g). This commitment is required ]nly until such time that the reanalysis for the OBE 1oading condition, and cny necessary modifications, is completed.
The exceptions to the completion 'of safety-related systems reanalysis involves the Fuel Pool Cooling and Purification Systen (FPCPS), the River Water
-n The FPCPS is defined in the FSAR System (RWS) and the OBE conditions.
However, since the facility has not completed as a safety-related system.
its first nuclear fuel cycle there is no spent fuel in the fuel pool and The failure of this system, the FPCPS is not required to be operational.
the public in the unlikely event of an earthquake, will have no e.'fect on For the purposes health and safety, plant operation, or plant integrity.
Show Cause Order, this system is not included in of the March 13, 1979 The licensee has committed the reanalysis required for facility startup.
to complete the reanalysis of the FPCPS using acceptable analfsis techniques and complete any necessary modifications to supports before spent fuel is placed in the pool.
The River Water System has an overstress condition in two branch connections Failure of these located on the discharge line in the turbine building.
branch connections in this location will not deprive any component of necessary cooling water and will not affect the functioning and structural integrity The RWS at this point is of any safety-related systems or components.
downstream from the coolant supply to vital safety components and since the RWS is a once-through system, failure of this portion caused by a seismic A portion of the discharge line event is clearly not a safety concern.
of the Raw Water Pumps that supplies cooling water to the turbine plant Although this portion of the piping was originally has not been reanalyzed.
seismically analyzed using algebraic summation, this portion of the line does not perform a safety-related function and since it is located in the its failure will not affect the functioning forebay of the intake structure The licensee has committed of any safety-related systems or components.
to complete the reanalysis of the RWS and make any necessary modifications
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prior to startup following the refueling outage.
The licensee has committed to reanalyze the safety-related piping to the OBE conditions and until that reanalysis is completed, to shut down and inspect the facility if a seismic event occurs which results in acceleratians Shutdown is the response greater than an acceleration level of 0.01 g.
This commitment essentially required by 10 CFR Part 100 for the OBE (0.06 g).
resets the OBE for the plant at 1/6 its previous valve and assures that no degradation of piping, supports, or nozzles will occur which might affec The accelerometer alarm is annunciated their capability to withstand the DBE.
The staff finds the 0.01 g for shutdown and inspecticii in the control room.
to be an acceptably conservative level for resumption of operation and until the OBE reanalysis is completed.
By letter dated July 23, 1979, the licensee requested the March 13, 1979 Show Cau n Order be terminated in its entirety based on the stated commit-nents and criteria in that letter and in Chapter Seven of the licensee's This was based on the fact that the licensee has June 15,1979 report.
completed the reanalyses for the DBE loading condition, including requir modifications, of all safety-related systems with the exception of the Fuel Pool Cooling and Purification Syste11 and the River Water System.
The commi',ments by the licensee in their July 23, 1979 letter would provide a consistent and more detailed " calculations-of-record" of all piping systems Al though and supports where computer analyses for pipe stress are required.
this additional effort is not intende. to provide an increase in the safety of the plant and is not required by the NRC for facility startup, the effort dification will establish a record by which the licensee can expedite facility mo in the future.
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_6-The licensee has stated its intent to complete the calculation-of-record effort before startup following the first refueling outage.
Based on the above, the licensee concludes that the analyses and modifications completed to date and commitments made in the July 15, 1979 (as revised) Report and in the July 23, 1979 letter demonstrate that, (1) why the suspension of facility operation good caJse has been shown:
should not be continued and the facility be permitted to operate and (2)
Show Cause Order shculd be terminated in its entirety.
the March 13, 1979 The licensee's analyses for operation are being performed using the SH0CK computer codes, which combine earthquake responses in a 3 and NUPIPE c'..
manner acceptable to the NRC staff. The reanalyses have resulted in sone stresses calculated above allowable.
In such cases, the licensee has recalculated the stresses using soil structure interaction (SSI) methodology with a 20 percent increase in the seismic acceleration between the fundamental The staff required this 20 percent increase periods of 0.4 to 0.55 sec.
to be applied to each pipe run after computer calculation of stress and This support loads in order to ensure an added factor of conservatism.
methodology, with the 20 percent increase, was approved by the NRC stati in its letter to the licensee dated May 25, 1979.
The neans by which piping responses are combined in the codes that are currently a basis for the facility design are summarized below:
rh PSTRESS/SH0CK 3_
This code combines the intramodal responses by the absolute value of response due to the vertical earthquake excitation to the (SRRS*) combin-ation of the responses due to the two horizontal eartheuake components.
The intermodal components are calculated by the SRRS method.
NUPIPE-SW This code combines intramodal** responses by the SRRS nethod and combines intermodal responses by SRSS or absolute sum for closely spaced modes.
(NUPIPE-SW and SSI methodology will be the basis for the calculation-of-record effort).
The NRC staff has determined that an algebraic summation of responses The NRC staff was not incorporated into any of the above listed codes.
has further concluded that these codes are acceptable for analyzing the f acility piping.
Based on the NRC stz.'f's Safety Evaluation, Actachment A, the staff finds that all safety-related piping systems including the reactor coolant system, engineered safety features, emergency core cooling systems, and all piping systems required to achieve and maintain safe shutdown or require <1 for accident nitigation have been reanalyzed and any required modification impiemented.
- SRSS - Square Root of the Suu of the Squares.
- " odes are defined as dynamic Diping deflections at a given frequency.
Intranodal responses are the conconents of force, nonent and deflection Intermodal responses are the components of force, moment within a mode.
and deflection of all modes.
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- IV.
The licensee to date has completed all of the actions identified in paragraphs
.1 and 2 of the Order to Show Cause dated March 13, 1979, except for (1) the fuel Pool Cooling and Purification System, (2) the River Water System, and (3) the OBE conditions.
In addition, the licensee has provided (1) justification for plant operation without the FPCPS in service and with overstressed areas in the RWS, (2) ccmnitm, ots for reanalyses of the FPCPS before spent fuel is placed in the 'uel pool, (3) commitments to reanalyze and modify the RWS prior to stt rtup following the refueling outage and (4) conmitments to shut down tN facility and inspect all affected systems if seismic accelerations at the site accelerometers exceed 0.01g.
The licensee has, pursuant to paragraph 3 of the Order, shown cause why operation of the facility should not remain suspended.
In the July 23,1979 letter, the licensee has also requested the March 13, 1979 Order be terminated.
The licensee's answer to the Order did not request a hearing. On April 2, 1979, the Pennsylvania Public Utility Commission (PUC) filed a request for a hearing and petition for leave to intevene. On April 9,1979, the PUC amended the April 2,1979 petition to state that it was requesting a hearing only if one or more of the following conditions exists:
f 1.
Any other party is granted hearing.
It is determined by the staff of the Nuciear Regulatory Commission 2.
that an extended period of cold shutdown for Beaver Valley Unit Mc.1 shall be necessary in order to make safety related modifications.
The Nuclear Regulatory Commission staff determination vis-a-vis 3.
the shutdown at Beaver Valley Unit No.1 is not forthcoming within a reasonable period of time.
With respect to these Conditions:
1.
No other party has requested a hearing.
Since this Order provides for operation, it does not 2.
mandate an extended shutdown to make modifications required as a result of this Order.
The PC staff has not received any objection from the PUC 3.
regarding the reasonableness of the time within which this action was taken.
Accordingly, pursuant to the Atoric Energy Act of 1954, as amended, the Commission's Rules and Regulations in 10 CFR Parts 2 and 50, and IT IS DETERMINED THAT:
The public health, interest or safety does not require the continued shutdown of the facility, AND IT IS HEREBY effective this date, the proceeding initiated by the ORDERED THAT:
Order is terminated and the following commitments of fi3rch 13,1979 the licensee are confirmed and required:
- r0 The spent fuel storage pool shcIl not be used to store spent fuel 1.
until an acceptable analysis and any necessary modification have been made to the Fuel Pool Cooling and Purification Systen.
The reanalysis of and modifications to the River Water System shall 2.
be completed prior to startup following the first refueling outage.
The Beaver Valley Unit No. I shall be shut down if the site accelerometers 3.
exceed 0.01 g and the licensee will inspect all safety-related piping systems which have not been reanalyzed and shown to be acceptable at Prior to resuming operations the licensee the 0.06 g level of the OBE.
will demonstrate to the Commission that no functional danage has occurred to those features necessary for continued operation without undue risk to the health and safety of the public.
FOR THE NUCLEAR REGULATORY COMMISSION Roger J. Mahson, Ac ing Director Office of Nuclear Re tor Regulation Dated at Bethesda, Maryland this day of ja+ j!9l7 hh
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