ML20028C067
| ML20028C067 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/27/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20028C065 | List: |
| References | |
| NUDOCS 8301050507 | |
| Download: ML20028C067 (8) | |
Text
l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.
23TO FACILITY OPERATING LICENSE DPR-77 TENNESSEE VALLEY AUTHORITY i
INTRODUCTION By letters dated May 25, August 6, August 12, September 9 and November 22, 1982, TVA proposed a significant number of revisions to the Sequoyah Nuclear Plant Unit 1, Operating License, DPR-77.
The proposed changes are requests to amend certain license conditions that cannot be completed during the designated period of time.
These conditions state that the specified modifications are to be completed prior to restart of Sequoyah Unit 1 after the first refueling.
Restart is expected on or about Decenber 24, 1982.
On September 29, 1982, a review meeting was held at the Sequoyah Nuclear Plant to discuss the reasons for TVA not fully complying with the license conditions.
One factor discussed at the meeting was the importance of maintaining the level of activities at the site to within the capabilities of the plant to reasonably nnage the workload at the site.
The number of modifications and their complexity were carefully reviewed by TVA in the preparation of the schedule for items to be completed during the planned outage.
Based on TVA's extensive experience with the Brown's Ferry facilities, it was detemined that the overall activities at Sequoyah during the outage of Unit 1, with Unit 2 at full power, must be limited to a 1900-2100 level of personnel on site. Representatives from Region II were generally in agreenent with the importance of limiting site personnel to the levels identified by TVA.
Having established an appropriate maximum manpower level for site activities, the outage manpower estimates for NRC commitments were reviewed in the context of other work that is on-going at the site.
The NRC licensed work was given hig.) priority among the items.
Also, it was evident that many of the NRC items are vefy exten-sive and require extremely high mar. power levels.
TVA stated that 45 days were added to the refueling and maintenance outage in order to complete as many NRC items as possible during this period.
Of particular interest, the installat?on of the permanent hydrogen mitigation system is identified as a critical path item, and this system will be comple ed during the current outage. We find that the TVA basis for manpower limitations and priorities is reasonable and acceptable.
The specific reasons for the delays of NRC license conditions were discussed in considerable detail to assure TVA pursued these items diligently and showed good faith in their efforts to complete the items.
A stsnmary of these discussions is provided below.
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. DISCUSSION Over/Under Voltage Protection License Condition 2.C.(18)(c) states that prior to startup after the first refueling, TVA shall have installed, demonstrated operable, proposed appro-priate Technical Specifications, and received NRC approval for an additional level of over/ undervoltage protection acceptable to the HRC staff.
The level of protection from the effects of power transients on safety-related equipment provided by Part I of the staff's " Degraded Grid Voltage Position,"
or equivalent, is required.
The undervoltage protection modification requires installation of new relays to provide the additional protection for safety-related electrical equipment in the event a degraded voltage condition develops in the offsite power supply.
The undervoltage relays have not perfomed satisfactorily.
Over the first several months of operation, the relay's setpoints were found to drift outside the tolerances allowed by plant technical specifications.
Surveillance intervals were increased in an attempt to keep the relays within their allowable range.
Experience to date has shown that a recalibration interval of less than a month is requirad to keep the relays within the allowable range (technical specifica-tion required surveillance interval is once each year).
The problem with the subject relays was initially thought to be just a matter of allowing sufficient burn-in time.
Experience since has shown that the relays are very temperature sensitive, and no improvement in performance is expected.
The manufacturer of these relays has developed a replacement relay which is presently being tested but will not be available for installation during the Unit I refueling outage.
Since completion of this modification requires a 2-unit outage, the earliest this modification can be planned is during the Unit 2 cycle 1 outage scheduled (at the earliest) for July of 1983.
This schedule t
would satisfy the Unit 2 license condition.
Low Temperature Overpressure Protection The 1.icense Condition 2.C.(20) states that prior to startup af ter the first refuel-ing, TVA shall install an overpressure mitigation system which meets 1RC require-ments.
Several instances of reactor vessel overpressurization have occurred in pressurized water reactors in which Appendix G limits have been exceeded.
The majority of cases have occurred during startup or shutdown operations while the primary coolant system was in a water solid condition.
The solution adopted for Sequoyah Unit 1 included (a) administrative procedures modification, (b) operator training, and (c) design modifications.
Item (c) was to be completed prior to startup of Unit 1.
Deferral of implementation of the low temperature overpressure mitigation system (OMS) on Unit 1 is required due to problems encountered by TVA with obtaining ade-quate operating times for the pressurizer PORVs at low pressures and on TVA's omce>
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. decision to use the pressurizer PORVs as a pressurizer vent system.
TVA modified the air supply to the PORVs at Sequoyah Unit 2 in an attempt to reduce the oper-ating time to meet the 2-seconds operating time required by the Westinghouse analysis.
The modification reduced the operating time to 2.8 seconds and resulted in TVA requesting a reanalysis of the setpoint.
Based on the Unit 2 modification, TVA cannot be certain that modification of the present valves will enable them to meet the times specified in the Westinghouse setpoint study.
TVA has decided to replace the air-operated PORVs presently installed at Sequoyah Unit I with electric solenoid-operated PORVs to be used as a " qualified" pressurizer vent system.
These new PORVs have operating times of 1.0 second in both the opening and closing dir-ections which is well within the setpoint limitations.
Expected delivery date for the new PORVs is Hay 1983.
Installation of the valves and associated instrumentation will require approximately 3,000 man-hours.
An outage duration of six weeks is required to install and test this equipment.
Control Room Design License Condition 2.C.(22)c states that prior to startup after first refueling, TVA shall complete the detailed Control Room Design Review.
As part of this review.
TVA shall consider benefits of installing da!.a recording and logging equipnent in the control room to correct the deficiencies associated with the trending of impor-tant parameters on strip chart recorders used in the control room.
By letter dated May 25, 1982, TVA stated that the detailed control room design review will be completed in accordance with the schedule to be specified for oper-ating reactors in NUREG-0700.
As part of this review TVA shall consider benefits of installing data recording and logging equipment in the control room to correct the deficiencies associated with the trending of important parameters on strip chart recorders used in the control room.
In the Sequoyah SER, Supplements 2 and 5, we stated that TVA has taken correc-tive actions to improve the operator effectiveness during an upset or accident condition.
The NRC concluded that Sequoyah could be safely operated with these improvements.
At the time the existing license condition was issued on Unit 1 of the Sequoyah Nuclear Plant, the license condition was thought to be consistent with the expected implementation schedule for the detailed control room review that would be included in NUREG-0700.
Since this schedule has changed significantly, and in order to be consistent with our understanding of the intent of the requirement as stated in SECY-82-111, TVA proposed changing the license condition to coincide with the sched-ule to be imposed on other licensees of operating reactors.
Reactor Coolant System Vents License Condition 2.C(23)E states that at the first outage of sufficient duration, but no later than startup following the first refueling outage, TVA shall install a reactor coolant system and reactor vessel head highpoint vents that are remotely nnnemhlo fem tho ennten1 rnert omct >
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. TVA has stated that the pressurizer PORVs would be utilized as highpoint vents.
This system meets the NUREG-0737 requirements with the exception of environmental quali fication.
As discussed in Section 5.2.2 on low temperature overpressure pro-tection, TVA plans to replace the existing PORVs with electric solenold-operated valves which will be environmentally qualified.
The schedule for this item will coincide with the aforenentioned item.
Additional Accident Monitoring Instrumentation 4
License Condition 2.C(23)D(2) states that at the Urst outage of sufficient dura-tion, but not later than startup following the first refueling outage. TVA shall install qualified monitoring instrumentation.
The following instrurnents will be delayed:
(a) Containment Pressure Monitor The design for a wide-range (minus 5 to plus 60 psig) containment pres-sure monitoring system qualified to the appropriate sections of Regu-latory Guide 1.97 as listed in appendix B of NUREG-0737 has been com-pleted for Sequoyah.
The equipment consisting of transmitters, power supplies, recorders, and indicators qualifted to IEEE 323-1974 was put out on bid invitation; the first bid invitation was opened January 8,.
1981. Three bids were received but none were responsive since they could offer only IEEE 323-1971 qualification.
The second bid invita-tion was opened on May 5, 1981. Only one bid was received and it was for IEEE 323-1971 equipment. The third bid invitation was opened on July 16, 1981, with only one bid and the same results.
liestinghouse is presently testing equipment to meet IEEE 323-1974 requirements.
The equipment failed the first test, and it is esti-mated that the retest will be finished "sometime" in September 1982.
Even if the retest is successful. TVA will receive the equipment too late for installation during the first refueling outage. Material delivery of qualified instrumentation for this modification is unknown.
Implementation of this modification will require a unit outage of approximately two weeks.
In the interim, TVA has installed redundant wide-range containment pressure indication utilizing IEEE 323-1971 equipment.
Pressure is indicated in the main control room. Other than in areas of quali-fications and the inability to record, the system meets the NRC requi rements.
(b)
Integrated Monitoring Assembly which will accomplish particulate, iodine, and noble gas monitoring TVA has not been able to procure an integrated nonitoring assembly which will monitor particulate, iodine, and noble gases and meet NRC design criteria.
Through discussions with NRC staff, several moni-tors were identified which NRC has found acceptable for satisfyina NUREG-072 7 requiremenus.
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. TVA design work and material procurement is continuing on this modi fication.
Bids for instrumentation that meet TVA specifications are expected to be awarded by January 1,1983, in hopes of material delivery by June 1,1983.
Final design work will not be possible until material contract award but is expected to be no later than the material delivery levels.
An outage of approximately two weeks may be required for each unit to tie in the sampling systems.
Detailed scoping will not be available until completion of final design.
TVA will inform NRC of a firm completion date upon con-tract award and completion of final design.
In the interim, Sequoyah will have installed high-range noble gas effluent monitors as follows:
A.
Monitors will be placed on the shield building vent and the condenser vacuun pump exhaust.
B.
Each monitor will' consist of two General Atanic Company monitors as follows:
1.
Model RD-1 with a range of 10~I to 10+4 MR/hr 3
2.
Model RD-23 with a range of 10 to 10 MR/hr The model RD-1 and R0-23 monitors each utilize an ionization chanber for the detector.
C.
The instrument readouts with continuous display and recording will be located in the main control room.
D.
The source of power for monitors will be preferred power (vital instrument bus).
Instrunents of Inadequate Core Cooling The license condition 2.C.(23)H.2 states that at the first outage of sufficient duration, but no later than startup following the first refueling outage. TVA shall install reactor vessel water level instrumentation and the system will meet seismic and environmental requirements.
The reactor vessel level systen is not scheduled for installation during the first refueling outage due to its severe impact on work activities at the site.
The system cannot be turned on until energency procedures utilizing the level system are developed, approved by NRC, and susbsequent operator training completed.
The Sequoyah Nuclear Plant procedure guidelines are being developed'as a generic effort CFFICE )
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i owners' group schedule. TVA estimates that the procedures cannot be in place and operator training completed until fall of 1983.
The level system therefore, if installed during this outage, could.not be used until very late into cycle 2 assuming an optimistic schedule. Delays in procedure development or NRC approval could. easily. prevent use of the level system until cycle 3.
Westinghouse has infomed TVA that additional analysis will.be necessary for plants utilizing ice condensers and/or upper head injection.
Sequoyah incorporates both in its design.
The magnitude of this work and the schedule for completion have yet to be deter-mined in view of the continuing uncertainties associated with this item.
i In addition, with present manpower limits, this modification cannot be completed
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as presently required.
The large amount of inside containment work.on this modi-fication requires a deferral-for completion because of the large amount:of inside containment work required by other NRC cemitment items.
The outside. containment t
4 work consisting of approximately 24,000 man-hours of the overall 55,000 man-hours will continue between the unit outages.
Post Accident Sampling The License Condition 2.C(23)F states that-at the first outage of sufficient dur-ation, but no later than startup following first refueling outage. TVA shall com-1 plete corrective actions needed to provide the capability to promptly obtain.and perform radioisotopic and chemical analyses of reactor coolant and containment-atmosphere samples under degraded core conditions with excessive exposure.
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TVA states that the probable material delivery date for all required material to cmplete this iten is March 1983.- Further vendor delivery problems could delay this-date by several months.
Implementation of this modification for both units :
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will require an additional 96,000 man-hours of nonoutage work and 41,000 man-hours of outage work.
Nonoutage duration after Unit 1, cycle 1 is approximately 39 weeks.
Approximately four weeks of outage time for each unit will be required after the nonoutage portion is complete for system tie in and testing. Because of the cur-rent schedule for the Unit 2, cycle 1 refueling outage, this will not allow TVA to
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complete this modification on Unit 1.
i In the interim, TVA procedures have been established to evaluate the primary cool-ant system activity depending on the accessibility of the sampling stations for particular degraded conditions.
Upgrade Emergency Support Facilities License Condition 2.C.(23)l(1) states that the installation of the TSC shall be completed prior to startup after the first refueling.- However, if an outage scheduled to last more than five weeks occurs after May 1,1982, installation of the necessary modifications to the control room and plant' instrumentation will be j
completed at that time and the-TSC hardware installation will be completed within eleven weeks of the start of this scheduled outage.
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7-In the response to NUREG-0694, TVA committed.to installing the permanent technical support center (TSC) by June 30, 1983. Since these license, conditions were estab-lished, equipment deliveries and design work have not kept pace with the expected schedule and will not be available to allow completion during the first refueling.
All required equipment delivery is expected to be complete by December 1982. The
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software program for the TSC computer system is being supplied by Westinghouse.
TVA's original schedule has not been met; expected delivery is now November 1982.
Modifications to this software package by TVA are expected by January 1,1983.
Implementation of this modification requires approximately 78,000 man-hours of non-j outage work and 7,000 man-hours of outage work for each unit. The nonoutage imple-i mentation duration is approximately 29 weeks. As currently scheduled, this will not be completed before Unit 2, cycle 1 outage work begins.
The outage work dur-ation is approximately 60 days for each unit. The magnitude of this work will not allow completion of the TSC before startup after the Unit 1 cycle 2 outage.
The relay room, which is adjacent to the main control room, is being used as the temporary Sequoyah TSC. The TSC meets the same habitability requirements as the main control room and is large enough to accommodate up to 25 people. The TSC communications include PAX telephones and-Bell telephones. The Bell telephones are l
administratively controlled, and system services can be reallocated during an emer-gency. Reference materials, including the REP, implementing procedures, plant drawings, FSARs, and selected plant procedures are present.
Respiratory protective l
devices are available if needed.
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I EVALUATION For each of the proposed items for deferral. TVA has identified equipment delivery delays, the unavailabilty of vendor material, the magnitude and complexity of the NRC effort required, and other problems that have impacted the schedules for com-pleting the listed items. Furthermore, TVA has set forth an integrated schedule for all activities during the planned outage to demonstrate that NRC commitments have high priority during this period and additional work within the outage period would exceed the capability of the plant to reasonably manage the activities. It is also noted that 45 days were added to planned outage period to perform as many NRC commitments as possible. The critical path item is the completion of the hydrogen mitigation system that will be completed during the outage.
The delay in the schedule of implementation of the items identified above, does not detract or reduce the level of safety existing at Sequoyah Unit 1.
We find the licensee has shown good faith and made a diligent effort to satisfy the license con-ditions.
TVA proposes that the delayed items be completed at the first outage of.-
suffichnt duration, but no later than startup following the second refueling outage.
This is acceptable to the staff.
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ENVIRONMENTAL CONSIDERATION We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any signif-icant environmental impact.
Having made this determination, we have further con-cluded that the amendment involves an action which is insignificant from the stand-point of environmental impact and, pursuant to 10 CFR Section 51.5(d)(4), that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
CONCLUSION We have concluded, based on the considerations discussed above, that: (1)because the amendments do not involve a significant increase in the probability or con-sequences of accidents previously considered, do not create the possibility of an accident of a' type different from any evaluated previously, and do not involve a significant decrease in a safety margin, the amendments do not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Comission's regula-tions and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date: December 27, 1982 Principal Contributor: Carl Stahle, Licensing Branch No. 4, DL F
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