ML19318B658
| ML19318B658 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 06/23/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8006270269 | |
| Download: ML19318B658 (9) | |
Text
s TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II June 23, 1980 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Denton:
In the Matter of the
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Docket Nos. 50-259 Tennessee Valley Authority
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50-260 50-296 Enclosed is Tennessee Valley Authority's (TVA) response to D. G. Eisenhut's May 7, 1980, letter to All Operating Reactor Licensees regarding five additional TMI-2 related requirements to operating reactors. TVA intends to be fully responsive to these additional requirements; however, we believe that a margin of flexibility (for good cause shown) in implementing these requirements is essential for the following reas;ns.
1.
As discussed in a May 29, 1980, presentation to the NRC staff, the modification schedule for Browns Ferry Nuclear Plant (BFNP) over the next two years is extremely tight and any additional modification requirements above and beyond those already scheduled will likely extend the existing schedule.
2.
Many of these requirements involve feasibility cr verification analyses before modifications can be implemented. These analyses must be per-formed on a very tight schedule in conjunction with General Electric (GE)
(and probably with support from the BWR Owners' Group). These analyses may indicate that the proposed modifications are unnecessary, counter-productive, or that additional modifications may be required. Therefore, these analyses have a high probability of impacting the proposed implemen-tation schedule.
3.
Many of these requirements will involve unreviewed safety question (USQ) determinations (per 10 CFR 50.59) and will likely require proposed changes to the BFNP technical specifications. These considerations will also have the potential to impact the implementation schedule.
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An Equal Opportunity Em;: foyer
. Mr. Harold R. Denton June 23, 1980 i
As previously stated, TVA intends to be fully responsive to the require-ments of the staff's May 7, 1980, request. We will make a best-faith effort to meet the proposed modifications schedules. However, in view of the above stated uncertainties, we cannot categorically commit at this time to meeting the proposed i=plementation schedule for these requirements.
Following a more comprehensive review of these requirements (by TVA, GE, and the BWR owners' Group), we may wish to meet with your staff to discuss specific problems (interpretation, schedule, etc.) regarding these requirements.
Very truly yours, TENNESSEE VALLEY AUTHORITY
.%M L. M. Mills, Manager Nuclear Regulation and Safety Enclosure i
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ENCLOSURE BROWNS FERRY NUCLEAR PLANT RESPONSE TO MAY 7,1980, NRC LETTER - FIVE ADDITIONAL TMI-2 ITDiS e
Item 1 - I.A.l.3 - Shift Manning TVA Responso - TVA withholds commitment on this item pending receipt of clarification documents referenced in your May 7, 1980, letter.
Item 2 - I.A.3.1 - Licensing Examinations TVA Response - TVA is incorporating the recommendations of the March 28, 1980, letter into our training program. Many of the provisions had been already included as a result of improvements recommended by TVA's nuclear review program following the TMI-2 incident.
TVA does not foresee schedule difficulty with the NRC dates with the exception of items D, E, and F of enclosure 3, of the March 28, 1980 letter, which will be included in the 1981 requalification programs.
This delay is due to the time to develop and incorporate the relatively new information required by these items.
Item 3 - I.C.5 - Licensee Dissemination of Operating Experience TVA Response - TVA will review and, if necessary, upgrade our present operating experience review procedures to comply with'the NRC outline.
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. Item 4 - II.K.3 - LOFW and Small Break LOCA General Review Matters Note: Many of the II.K.3 items will be handled in conjunction with the BWR Owners Group.
II.K.3.3 - Reporting Safety and Relief Valve Failures and Challenges 1
TVA Response - TVA will comply with the requirements of position II.K.3.3.
Plant procedures will be revised to require prompt notification if a relief valve fails to close. This prompt notification will be made.via
-the telephone line used to report 10 CFR 50.72 events; technical specifications l
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will not be amended.
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II.K.3.13 - Separation of HPCI and RCIC System Initiation Levels -
Analysis and Implementation' TVA Response - TVA will evaluate the feasibility of separating the HPCI/RCkC initiation setpoints and adding auto-restart capability to RCIC.
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II.K.3.15 - bbdify Break Detection Logic To Prevent Spurious Isolation i
of HPCI and RCIC Systems TVA Response - TVA has previously modified the differential pressure sensor configuration on HPCI to minimize spurious isolations from pressure spikes. We will evaluate modifying the differential pressure sensor configuration on RCIC.
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II.K.3.16 - Reduction of Challenges and Failures of Relief Valves -
1 Feasibility Study and System Modification
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j TVA Response - Browns Ferry utilizes eleven safety / relief valves with of fset actuation setpoints to minimize the number of valve openings per challenge.
In addition, we have lowered the MSIV isolation level setpoint by 20 inches. This modification significantly reduces reactor vessel isolation and subsequent relief valve ' actuation and gives the operator additional time to manually initiate high pressure injection systems or return the'feedwater system to service prior to vessel isolation.
i Challenges to the relief valves have been substantially reduced by the i
above methods. However, TVA will initiate a feasibility study in an attempt tof identify methods / techniques to further reduce relief valve challenges.and failure rates..
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~II K.3.17 - Report on Outage of ECC Systems - Licensee Report and Proposed Technical. Specification Changes
.TVA Response - TVA will provide the requested information.
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II.K.3.18 - Modification of ADS Logic - Feasibility Study and Modifications for Increased Diversity for Some Event Sequences TVA Response - TVA will conduct or participate in a study to evaluate the f easibility and risk assocf ated with the need for eliminating the need for manual ADS actuations during specific events.
II.K.3.21 - Restart of Core Spray and LPEI Systen.s on Low Level - Design and Modification TVA Response - TVA will evaluate the potential benefits and risks associated with adding auto-restart capability to both RHR and core spray systems. However, we do not believe that auto-restart of RHR and core spray is warranted.
The proposed modification will significantly increase the complexity of a complex logic system, has the potential to adversely effect overall system reliability due to the increased com-plexity, may have an adverse effect on shutdown boards and standby power systems due to increased loading from CS and RHR pump auto-restart, and will reduce operator flexibility when responding to abnormal events.
II.K.3.22 - Automatic Switchover of RCIC System Suction - Verify Procedures and Modify Design TVA Response - Procedures exist for manual switchover from the 375,000-gallon condensate storage tank to chi suppression pool. With a discharge capacity of 500 gpm and a 375,000-gallon suction source, TVA sees no benefit in adding automatic switchover capability to RCIC. During events that require significant amounts of high pressure coolant injection, the 5,000 gpm HPCI system is relied on to provide the required coolant flow.
Failure of HPCI to operate would result in operation of the auto-matic depressurization system and the low pressure injection systems.
RCIC is not relied on during events that require a significant amount of coolant addition.
Consequently, TVA does not plan to add automatic switchover capability from the condensate storage tank to the suppression pool.
II.K.3.24 - Confirm Adequacy of Space Cooling for HPCI and RCIC Systems TVA Response - As discussed in our response to Browns Ferry FSAR questions 4.8 and 4.9, the RCIC and HPCI systems are expected to operate for up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.. We will reevaluate TVA's basis for that position to determine if additional testing is required.
II.K.3.25 - Effect of Loss of AC Power on Pump Seals TVA Response - TVA does not consider additional demonstration of recir-culation pump seal adequacy as necessary.
Recirculation pump operation is not required to mitigate accidents and transients.
The sufficiency of natural circulation to maintain adequate core cooling has been demon-strated in numerous analyses.
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, Cooling water to remove the heat of the sealing surfaces is provided to prevent damage.to the pump seals.
On loss of cooling water, operating procedures call for removal of the pump from service.
Seal cavity temperature indications, seal pressure indications, and seal flow Hi/Lo annunciators are available in the control room.
Total leakage from the seal assembly, assuming total failure of both seals, would be limited to about 60 gpm by the breakdown bushing.
Remote isolation of the pump is still possibic in this condition by closing the pump suction and discharge valves.
II.K.3.27 - Provide Common Reference Level for Vessel Level Instrumentation TVA Response - TVA does not find the present level instrumentation
' configuration confusing. Further, each control room has a vessel level instrument range chart posted on the control panel which can be used to quickly interrelate any level measurement.
II.K.3.28 - Study and Verify Qualification of Accumulators on ADS Valves TVA Response - Air to the ADS is normally supplied by the compressed air system. However, the air supply may be swit'ched to the plant air system i
to provide an additional air source with independent supply line and header. These air supplies are periodically tested to prevent excess leakage. The ADS valves have " soft seat" check valves and are periodi-cally tested to ensure leak tightness.
TVA will reexamine the present' testing methods to determine if additional testing is necessary.
.K.3.30 - Revised Small-Break LOCA Methods to Show Compliance with
.0 CFR 50, Appendix K TVA Response - TVA withholds commitment on this item pending receipt of NUREG-0660.
1 II.K.3.31 - Plant Specific Calculations to Show Compliance with 10 CFR 50.46 TVA Response - TVA withholds commitment on this item pending receipt of NUREG-0660.
II.K.L44 - Evaluation of Anticipated Transients with Singic Failure j
to Verify No Fuel Failure t
f TVA Responso - The analyses requested by this item appear generic. - TVA j
proposes to work with Cencral Electric Company or the BWR Owners' group l
to Identify cases which may have not been,previously identified.
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. II.K.3.45 - Evaluation of Depressurization with Other Than ADS TVA Response - TVA will work through General Electric or the BWR Owners' group to provide the requested analyses.
II.K.3.46 - Response to List of Concerns from ACRS Consultant TVA Response - TVA commits to review the General Electric response to the Michelson concerns as they relate to Browns Ferry.
II.K.3.57 - Identify Water Sources Prior to Manual Activation of ADS TVA Response - TVA will ensure that the emergency procedures that require or direct manual ADS initiation have provisions to verify availability of low pressure water sources.
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. Item 5 - III.D.3.4 - Control Room Habitability TVA Response - TVA will review control room habitability to ensure that workers are adequately protected f rom radioactivity, radiation, and other hazards, and that the control room can be used in the event of an emergency.
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