ML20101F678
| ML20101F678 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/15/1984 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML20101F655 | List: |
| References | |
| NUDOCS 8412270269 | |
| Download: ML20101F678 (7) | |
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TENNESSEE:lWdi1EE,[
rhRITY CH ATTAP D G '.
NES EE 37401 400ChestnutStreetToDrb 84 0C122 A October 15, 1984 U.S. Nuclear Regulatory Ccamission Region II ATTN: James P. O'Reilly,. Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
Dear Mr. O'Reilly:
Enclosed is our response to your September 13, 1984 letter to H. G. Parris transmitting Severity Level III Violation (No Civil Penalty)
EA 84-82 Violation Resulting from Design Review Deficiencies (Inspection Report Nos. 50-259/84-20, -260/84-20, -296/84-20) for our Browns Ferry Nuclear Plant which appeared to have been in violation of NRC regulations. We have enclosed our response to the Notice of Violation.
If you have any questions, please call Jim Domer at FTS 858-2725.
To the best of my knowled7e, I declare the statements contained herein are complete and true.
Very truly yours, TENNESSEE VALLEY AUTHORITY Y
L. M. Mills, Manager Nuclear Licensing Enclosure 8412270269 841121 i
PDR ADOCK 05000259 An Equal Opportunity Employer
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BVCLOSURE
' RESPONSE ID SEVHtITY LEVEL III VIOLATION (NO CIVIL PENALTY) EA84-82 VIG.ATI(N RESULTIMi FROM DESIGN REVIEN DEFICIIFCISS (REFERENG INSPEC1' ION REPORT NOS. 50-259, -260, -296/84-20)
I, 10CFR50, Appendix B, Criterion III requires that measures shall be y
established to assure that applicabl a regulatory requirements and the de sign ba sis, as defined in 10 CFR 50.2 and as specified in the license applica tion, for those structures, sy st em s, and components to which Appendix B applies, are correctly translated into specifications, I
drawings, procedure s, and instructions.
f A.
Contrary to the above, this requirement was net met in that if an accident signal had been present, the diesel generators would have been innibited from working in parallel operation to supply all required loads for the long term (greater than 10 minutes) saf e shutdown and cooldown of all three units in the event of loss of off-t site power and a design basis accident in any one unit, as called for in the S af e ty De si gn Ba sis (FS AR, Sec tion 8.5).
B.
Contrary to the above, dhe exhaust f ans and recirculating air conditinning units for cooling the shutdown board rooms for units 1, 2, and 3 were designed such that sufficient support equipment might not have been available to cool the shutdown boards during an accident with a coincident loss if off si te power.
C.
Contrary to the above, the Ecgine%> cd G:f ognard bystem indepe ndence criteria and design basf for electrical cable sepa.ation criteria (FSAR, section 8.9) for the installation I electrical cables for the automatic depressuriza tion syt sem (ADS). 2d the high pressure coolant inj ection (HPCI) system were not met.
D.
Facility operating licensee of units 1 and 2, as amended respectively by Amendment 27 for paragraph 2.C(4)
.d Amendment 14 f ir para graph d
g 2.C(5), permit the f acilities ' to be modified as described in Section X of " Plan for Evalua tion, Repa i r, and Return to rervice of Browns Ferry Units 1 and 2 (March 22.1975)" dated April 13, 1975, and revisions thereto.
"Pl an for Evalua tion, Repair, and Return to Service of Browns Ferry Unit s 1 and 2 (March 22,1975)" dated April 13,1975, Part I, Section A.3.1.2, as revised, requires that cables associated with valves a ssigned to the ADS be separated from cable s associated with manual relief valves by rerouting as necessary in separate conduit s and cable trays.
Contrary to the above, initial modification to achieve the required separation for units 1 and 2 was inadequate and subsequently made verse by later modifications.
E.
Contrary to the above, six building heating line s be tween the turbine building and the reactor building are neither seismically qualified nor do they contain isolation valves.
1.
Admission or Denial of the Allened Violation
'IVA admit s the viola tion as discussed in items A through E.
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'2. ' Reason for Violation A. ' This error occurred during origina1 ' design because the designer assumed the accident signal would not be present af ter 10 minutes, when in fact it did not reset. - This factor was also overlooked g
during the early plant de, sign review.
Ei B.
Due to a misinterpretatios'of? the 10-minute rule, the discrepancies were not discovered duridt the ' initial design review process Design N
personnel assumed an accident signal' would not be present af ter 10 Bs minute s and then plant op'erators woul'd be able to re set the b
ventilation syst em. -
Additionc11,. conflicting design criteria 7
j statements for the ventilation and cooling system caused redundant i
loads to be powered from the same electrical board, in some J
in st a nce s.
1 U.
Electrical separation requirasoEts were developed while Browns-Ferry (BFN) was in the design stage. ' General Electric Specifica tion 22 A2 809 R1 ~, Elecrical Equipment, Separation for Safeguard Sytems, f o rme d the ba si s f or BFN ele c t ri c al se para tion.
Two electrical divisions were defined.
ADS was assigned to Division I and HPCI was b
a ssigned to Division II.s '(yoth syst ems are single trained and are considered redundant to each other.
Since the HPCI is driven by reactor steam, its steamline isolation valves are part of the primary All p' imary containment inboard -
containment and must be redundant.
r isolation valves were assigned to Division I,,and the outboard valves were assigned to Division II.
Hence, redundant functions were placed l
in the same division. This led to ADS cables being routed in the same cable trays as cables for the HPCI statuline finboard isolation valves.
NRO-OIE Information Notice (IN) 79-32 was issued to provide utilities l
an early notification on a potential prbblen,concerning HPCI and ADS cabl e separation. TVA investigated this condition for applicability 5
to BFN.
3 The conclusion of this investigation was that while TVA design criteria on divisional separations of the controls for these systems had been met, the condition documented in IN 79-32 did exist at BFN.
H ow ev'e r, IVA f ailed to track this item through to re solution.
t D.
During 'the BFN fire recovery effort, it was recognized that a cable t sy fire potentially could disable all safety relief valves (SRV) remote actuation capabilities, the inboard main steam isolation valves (MSIVs), and the Peactor Core Isolation Cooling System (RCIC),
and HPCI syst ems.
In October 1975, a modification was proposed to separate the manual SRVs from the SEVs with the ADS logic to address this cable tray fire concern.
Two errors occurred during the design of this modification. First, only the control cables were separated.
Potential causon routing of the SRV power cables was not inv estiga ted, and problems did exist which were not corrected.
Second, the cable schedules were issued without an intended note j'
documenting the manual versus ADS cable separation reqcirements.
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- Duriss 1976, modificaticos intended to provide ccre symmitriosi Ioads on the torus when actuating the ADS SRVs were designed which removed the ADS logic from four SRVs (making them manual), and placed this logic on four manual SRVs.
To maintain manual versus ADS separation requirements, cable reroutes should have been perf ormedp l
h ow ev e r, the manual versus ADS separation requirements were
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ov erl ooke d. -
E.
'The violation is attributed to the lack of of fective engineering procedures a t the time of the issue of the design drawings (January 1969).
3.-
Corrective Stens Taken and Results Achieved A.-
Immediate corrective action was to revise plant operating instructions to include temporary procedurcs to establish paralleling capabili ty.
Approval f or modifications to correct the design violations was giron on May 11, 1984. Field change requests were issued for all three units to allow immediate wiring change s.
An ECN P5096 was issued on May 10, 1984, to revise all af fected de sign drawings per the applicable FCRs. The logic wiring changes have been impl emented f or all units, and paralleling of the diesel generators has been succe ssf ully tested.
B.
The plant operating instructions and emergency operating instructions were revised to include appropriate action to be taken upon loss of air-conditioning or ventilation for the various shutdown board rooms.
These instructions include jumpering the 480V load s'aed logic contacts on. units 1 and 2 fans that are affected within the first hour of losing ventilation and/or providing an exhaust path in the f an duc twork.
C.
A saf ety evaluation was conducted which concluded that no saf ety concerns existed different f rom the situation discussed in IN 79-32.
Consi stent wi th IN 79-32 recommenda tions, fire watches were established to monitor areas of inadequa te cable separation. The roving fire watch and administrative controls remain in effect as compensatory measures until long-term modifications are completed.
D.
A GE study (NEDD-24266) has been performed to support ADS single f ailure evalsstions. The study concludes that manually actuating four SRVs with an assumed 10-minute delay in operator action preserves adequa te depressurization capability. Based on this, th e SRV cable routings were reviewed for both power and control circuits.
If four SRVs (manual mode) were not separated by the FSAR requirements for divisional separation, then the HPCI Division I cable routing was reviewed to see if HPCI plus one SRY (manual mode)
I would be available. Units 1 and 3 met the se limit s.
Unit 2 and interactions which invovled HPCI and 11 of 13 SRVs.
This lef t two SRVs available in the manual mode.
Unit 2 had been operating at about 60 percent f ull power level to provide a longer operating cycl e.
An evaluation concluded that depressurizing with two SRVs would remain within FSAR analyzed conditions if the power level was l l
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1.icited to 60 percont.- To providr be ttcr cargin, a =odificatics ecs
'made f or unit 2 ' to make f our SRVs available if HPCI plus one 'SRV were not available.
Operating ' instructions were revised to address these considerations and live time training provided to operations personnel.
Upin completion of the unit 2 modifications, the administrative controls were-revised to reflect the modifica tion, were reviewed by PORC, and approved.
Live time training was conducted again. Al so, the fire watches which had been posted since May 8,1984, were r em ov ed.
These fire watches were reposted following concerns expressed in a telecon with NRC-OIE, Region II, on Way 30,1984. A modified version of these fire watches remains in effect.
E.
An analysis was performed to determine if secondary containment i..tegrity can-presently be assured with these line s open, based upon the latest secondary containment leak testing data.
The analysis showed that there is adequata reserve f an capacity in the standby gas treatment syst em (SGTS) to ensure the necessary negative pressure inside secondary containment under postaccident condi tion s.
One of the following two options will be implemented for final resolution of the viola tion:
- 1) Rev ise the existing surveillance instructions for the SGIS to include allowance in the flow tests for the openings in the six building hea ting line penetra tions, or
- 2) Qualify these line s.
4.
Corrective Steos Taken to Avoid Further Nonconnliance A.
Engineering procedures training and utilization program initiated on February 26, 1982, required documented training for applicable personnel in OE procedures including procedures governing all aspects of de sign review. This ongoing program should prevent any future i
noncampliance in this area.
Onsite design personnel will al so be avail able - f or quick and effective action for any additional problems that might be l
discovered.
B.
Same a s A.
A design study is currently in progress to recommend a long-term l
corrective action to include a manual restarting of the exhaust f ans and making the ventilation system redundant to the air-conditioning system by changing their power supplies -(see item 5.B for schedule).
C.
Long-term corrective action will consist of separating the U)S from the HPCI Division I cables to ensure that the single f ailure criteria is met.
E04 P-0753 has been written to accomplish this modification and separation criteria has been defined for this specific change.
In addition, a BFN design criteria for electrical separation will be
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prepared to provide a' single; corres documset on this subj ect.
This de' sign : criteria will include the general requirement s and special cases (such as the ADS versus HPCI Division I cables). Use of this document will provide be tter understanding among 'IVA. designers of BFN's electrical separation-scheme and will lead to more consistent applica tion of the licensing basis requirements..
With regard to review and resolution of ins, circulars,.etc.,
,.~.ernal procedure-were revised in 1983 to ensure better.
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documentation of excestiga tions.
In addition, action items for
. perfonains invesi sations of NRC information notices and circulars are being inputed in the Tracking and Reporting Open Items (TROI) system to ensure management attention is given to investigation re solutions. All ins and circulars received from 1979-1983 will be reviewed to ensure inve stiga tions were completed. This review cambined with the previously revised procedures will provide better assurance that ins and circulars are properly reviewed and resolved.
D.
As part of BFN's compliance with 10CFR50, Appendix R,. SEV control and power cables will be separated to meet Appendix R requirements so that four SEVs (manual mode) wil1 ~ be available for a fire located anywhere within the reactor building.
ECN P0822 has been prepared to install this modification as part of.the modifications being proposed to meet Appendix R.~
Please note that separation of manual SRVs frca
- ADS SRVs is not being committed to, as the Appendix R modification (ECN P0822) will supersede the commitment made in section I of " Plan for Evalua tion, Repai r, and Return to Service of Browns Ferry Units 1 and 2 (March 22,1975)" dated April 13, 1975, and revisions thereto.
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A program is being established to document th e de si gn ba si s f or th e Appendix R modifications and required equipment.
The overall de sign process will include a review of this Appendix R design basis documentation for all further design modification proposals.
The review will be to ensure the proposed modification will not adversely affect the Appendix R de sign ba sis.
E.
No additional action to prevent further noncompliance is required since EN DES-Engineering Procedures 3.10 - De sign Verification l
Nethods and Performance of Design Verifications, and 4.01 -
Signatures / Initials For Preparation, Rev iew, and Approval of IN DES Drawings were issued to provide for design review and verification necessary for compliance with 10CFR50 Appendix B.
These procedures l
were issued August 8,1974, and September 4,1973, respectively, f
5.
Date When Full Como11ance Will Be Achieved A.
Field modifications (rewiring of logic controls) for the diesel generators have been ' completed and the diesel generators have been tested for their paralleling capability. Drawings reflecting thess modif ica tions, per ECN P5096, are in the review process and are scheduled for issue on October 31, 1984, i
B.
LER BFR0' 50-259/ 84022, revision 2, dated August 8,1984, commits TVA j
to address the long-term proposed changes in a memorandum by J anua ry 1, 1985. -
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,a C.
ADS and HPCI Divisics I esbles will b3 separated during the next scheduled refueling outage f or each unit.
Thus the schedule is:
natt 2/C5, unit 1/C6, and unit 3/C6. The BFN de sign criteria for
- el ect rical suparation will be issuet by September 1985. The review and identification of all outstanding items for all ins and circulars received f rca 1979-1983 will be completed by February 28, 1985.
l D.
Em P0822 will be scheduled for installation in accordance with the six year integrated schedule currently being reviewed by NRO-NRR.
'Ihe Ap.pendix R de sign basis documentation will be issued before final implementa tion of Em P0822.
E.
The -EN DES Engineering Procedures which control _ de sign review and verification were effective as of the issue dates noted in item 4.
Therefore, full compliance to prevent recurrence has been achieved.
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