ML20096C024
| ML20096C024 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/07/1992 |
| From: | Joshua Wilson TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M51203, TAC-M51204, NUDOCS 9205130124 | |
| Download: ML20096C024 (10) | |
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4 nn,nem.m. n e u +, n o., n o JL hon W o ht9 ted k p., # P!h i: Dor May 7, 1992 U.S. Nuclear Regulatory Commission ATTN: Docur..ent Control Desk Washington, D.C. 20555 Gentlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SQN) - DETAILED CONTROL ROOM DESIGN LEVIEW (DCRDR) IMPLEMENTATION STATUS REPORT (TAC No.M51203/51204)
References:
1.
TVA letter to NRC dated November 25, 198/, "Sequoyah Nuclear Plant (SQN) - Detailed Control Room Design Review (DCRDR) Supplement to Sunanary Report" 2.
TVA letter to NRC dated November 26, 1986, "Sequoyah Nuclear Plant (SQN) - Detailed Control Room Design-Review" The purpose of this letter is to inform NRC of the implementation status of resolutions for DCRDR human engineering deficiencies (HEDs).
The resolutions of these HEDs are commitments documented in the references.
During the Units 1 and 2 Cycle 4 refueling outages TVA implemented resolution of the Category 1 HEDs.
In addition, many Category 2 and 3
'HEDs involving modifications on the same panels affected by the Category _1-HEDs were implemented. The documentation supporting the resolution of the Category 1 HEDs has been verified and is maintained in retrievable status.
During the Unit 1 Cycle 5 refueling outage, the remaining Unit 1 Category 2 HEDs were resolved.
TVA reviewed the Category 2 HEDs identified -in Reference 2 to verify the appropriate categorization in view of facility changes since the original DCRDR evaluations. This review identified four Unit 1 Category 2 HEDs that were no longer considered to constitute Category 2 HEDs based on modifications completed and operational considerations as detailed in Enclosure 1.
Two of these HEDS have been downgraded to Category 3 and additional actions for resolution will be j
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'4ay 7, 1992 evaluated and implemented as necessary by the end of the Unit 1 Cycle 6 refueling outage.
The other two !!EDs were downgraded to Category 3, but have since been evaluated and determined to require no further actions.
These two llEDs have been closed.
Five Category 2 IIEDS were associated with common equipment and are being resolved during the present Unit 2 Cycle 5 refueling outage as stated in WA's connitment.
identifies these llEDs. Two Category 2 IIEDs for Units 1 and 2 were determined to require no action for resolution. The details of these determinations are contained in Enclosure 3.
TVA will resolve the remaining IIEDs-that meet the criteria for Category 2 by the end of the present Unit 2 Cycle 5 refueling outage. TVA will.
i review the remaining Category 3 IIEDs to verify they still meet the DCRDR criteria. These llEDs will be evaluated for cost-benefit considerations, and TVA management will determine the !!EDs to be resolved by the end of the Cycle 6 refueling outages.
TVA will provide NRC with the results of the !!ED evaluation and the justification for llEDs deleted f rom the DCRDR resolution offorts. provides the new commitment contained in this letter.
Please direct questions concerning this issue to 1:elth Weller at (615) 843-7527.
Sincerely,
.5 W
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l L. Wilson Enclosures cc (Enclos".res):
Mr. D. E. LaBarge, Project Manager i
U.S. Nuclear Regulatory Connission i
One White Flint,1 North l
11555 Rockville Pike Rockville, Maryland 20852 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 l
Mr. B. A. Wilson, Project Chief l
U.S. Nuclear Regulatory Commission Region 11 101'Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-l iL-
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ENCLOSURE 1 a
UNIT 1 CATEGORY 2 IlUMAN ENGINEERING DEFICID401ES (llEDs)
REEVALUATED AS CATEGORY 3 The following Unit 1 HEDs werr downgraded to Category 3 before start-up from the Unit 1 Cycle 5 refueling outage.
Further evaluations to determine th3 final resolutic-of these llEDs will be continued as category 3 items and will be completed by the end nf the Unit 1 Cycle 6 refueling outage.
HED 3173 Need better annunciation for Phase A. Phase B, and containment vent and indication of reset.
PROPOSED _CORRECIION Provide consistent Phase A, Phase B, and containment vent isolation and/or reset indication on a signal basis.
This llED is considered to have a partial correction because the recommendation for reset indication (addition of amber and blue light circuits) was determined to be unnecessary.
The clearing of an annunciator window will provide indirect indication whenever a signal has been reset.
ItAS_IS E01LCATEGORL3_CIASSIEICAT. ION The Category 2 corrective action for ilED 3173 was to add annunciation for Train A or B actuation of containment isolation Phase A, containment vent isolation, and auxiliary building isolation on main control room (MCR)
Panel 1-M-6.
Deletion of trained annunciation for control room isolation on MCR Panel 0-M-27B (two windows) and addition of a single window for Train A or B on MCR Panel 1-M-6 were implemented.
The above annunciators were placed together with containment isolation Phase B and feedwater isolation on MCh Panel 1-M-6.
Further actions beyond this grouping on MCR Panel 1-M-6 will be evaluated as a Category 3 item.
11ED 5020 Use of zone coding.
EROP_0 SED _CORRECIION Implement a plant standard for zone coding to be used on MCR and auxiliary control room meters; implement a plant procedure for the application of zone coding.
HED 5020 (Continued) l' AS I S_IOR_CATEGO RX1 CIA S SI EICAT10N The Category 2 <
welive actions for HED 5020 are as follows:
A design standard E18.1.22) has been implemented that provides a standard for zone co ing to be used on MCR and auxiliary control room indicating meters that are under design control.
This is referred to as
" color banding" in this standard.
For coding not within design control, SQN Standard Practice (SQA) 142 Revision 11. " Control of Operator Aids," has been written.
If associated with SQA 142, zone coding will be classified as an " operator ald" and controlled as such.
Zone coding has been added to indicators (1-EI-57-33, 1-EI-57-49, 1-El-57-60, and 1-El-57-76) located on MCR Panel 1-M-1.
Because 1-EI-57-39 L 66 have been replaced with updated digital meters, coding on these meters is not required.
Further evaluations to address operational concerns f or zone coding of specific instrumentation will be continued for this HED as a Categor) 3 item.
The following Unit 1 HEDs were downgraded to Category 3 before start-up from the Unit 1 Cycle 5 refueling outage.
Further evaluations have determined that the corrective actions taken have adequately resolved these concerns and no further actions will be required. These HEDs have been closed.
HED 379 Main steam line radiation monitors are needed.
PROPOSED _CQRRECTION Modify scope of Engineering Change Notice L6539 to include installation of equipment that detects steam generator (SG) tube leakage.
BASlS_ ERR _ CLOSURE Radiation monitors were installed in close proximity of the main steam lines with indication provided on MCR Panel 1-M-30 and recording on MCR Panel 1-M-31.
The radiation monitors are primarily used for postaccident monitoring of large tube leaks.
In addition to the radiation monitors, Abnormal Operating Instruction (AOI) 24, Revision 13, " Steam Generator Tube Leak," has been revised to instruct operators in dealing with two sizes of SG tube leaks:
1.
Leaks large enough to cause an increase in charging flow, but pressurizer level is maintained.
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Leaks small enough to not have a noticeable affect on charging flow, but large enough to be detected by condenser vacuum exhaust and SG blowdown radiation monitors.
Symptoms of a tube leak could be any of the following alarms or indications:
1.
Condenser vacuum pump air exhaust monitor high radiation alarm 2.
SG bir;wdown liquid monitor high radiation alarm 3.
SG blowdown 11guld sample monitor high radiation alarm 4.
Main steam line monitor high radiation alarm S.
Charging flow increases to maintain pressurizer level 6.
Increased make-up to volume control tank The instruction details the followin6 methods for identifying an SG with tube leakage:
1.
SG blowdown radiation monitoring 2.
Chemistry laboratory sampling 3.
Unexpected rise in SG 1evel 4.
Radiation survey of main steam or blowdown lines For small leaks, A01 24, Appendix A, details a system of SG tube leakage monitoring using existing plant equipment that is capable of responding to rapidly propagating SG tube cracks without reliance on time-consuming chemistry sampling.
SG blowdown and condenser vacuum radiation monitors have an output correlation to SG tube leakage detailed by the figures in the appendix.
HKD 3015 P
There are many alarms that require the operator to send for infonnation to determine required action.
ER0EOSED_CORRECIION Perform a further evaluation of annunciators that require information f rom outside the control room for determining required actions.
BASIE_ EOR _ CLOSURE A.
A new annunciator system has been installed tha has the capability to separately identify multiple input points that previously went to a common alarm window.
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The new system enhances the ability of the operator to identify inputs of discrete points that go to common windows, by adding cathode ray tubes in the MCR that will show the description of the point. This includes those points that were previously only recorded on the communications room sequence of events recorder.
C.
Alarms with multiple field contacts feeding a single signal. path normally require personnel to be dispatched to the area for observation _and initiation of any required corrective action. For example, blown fuse indicators require visual confirmation and fuse replacement at the fuse panel, as a minimum.
Since additional alarm information would not significantly change actions taken or personnel involvement in such ccses, no further corrective action was deemed necessary to resolve this HED.
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ENCLOSURE 2 CATEGORY 2 frJMAN ENGINEERING DEFICIENCIES (llEDs)
ASSOCIATED WITil COMMON EQUIPMENT IIED 217 Layout, demarcation, grouping and order discrepancies on Panci 0-M-271).
HED 219 Layout of Fanel 0-M-27A is confusing because of mirror imaging,.
disassociation of controls, and the presence of "depowered" hand switches.
IIED 320 Control room communications (horseshoe areas).
l-HED 2008 Communications - sound-powered phone systeas - improve system and equipment.
IIED 2010 Communicatior.s - hand-held radios - do not provide complete coverage of plant site.
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ENCLOSURE 3 CATEGORY 2.TJMAN ENGINEERING DEFICIENCIES (HEDs)
DETERMINED TO REQUIRE NO ACTION HED 210 The main feedwater (FW) bypass valves do not have control room indication of their status.
l'R0EOSED_ CORRECTION Add open and close limit switches to the FW bypass valves, and add status lights to main control room (MCR) Panel M-3 that utilizes a 2 by 4 matrix of MSC 800s with push to test circuits. Alternative Provide feedback of actual valvo position.
DAS.1E_ EOR _ CLOSURE FW from the pumps and heaters passes through the FW regulator valves; Flow Ccntrol Valves (FCV) 35, 48, 90, and 1038 and Bypass Valves FCV-3-35A, 48A, 90A, and 103A through FW flow indication Loops F-3-35, 48, 90, and 103.
From here, FW enters the steam generators (SGs) that are equipped with level transmitters (LTs) to indicate SG 1evel and alarm out-of-tolerance conditions.
The concern assoelated with this HED is the " operator not knowing if valve does not close on a FW isolation" signal. Also stated'in the HED is:
"The only main FW bypass valve position indication is from the demand indicators on the valve controllers. This is only a demand signal and not en actual position.
Even though the controller was sending a close signal, the cperator has no immediate way of identifying that the valve is not closed."
Further in:estigation of this HED revealed that the concern above-is not a significant problem. The operator can verify valve closure and FW isolation three ways 1.
If FW isolation does not occur, the level in the SG will rise and be indicated by the level changes detected by the LTs and displayed on various loop-associated instrumentation.
2.
If FW isolation does not occur, flow through the FW flow indication loops will be displayed on MCR Panel M-4 and be available via the Technical Support Center and P250 computer.
- 3.- -If bypass valve closure-does not occur, FW isolation can still be achieved by way of FW Isolation Valves FCV-3-33, 47, 87, and 100, which have valve position indication at their respective hand-switch controls on MCR Panel M-4.
SG 1evel indication, FW flow indication, and FW isolation valves indication are provided in the control room.- No additional indication is required for main FW bypass valves, as the operator can use any one of the above indicatic :s to determine FW bypass valve status.
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HED 210 (Continued)
This HED was downgraded to Category 3 before start-up f rom the Unit 1 Cycle 5 refueling outage.
Furl 5er evaluation by plant management has determined that there are no actions required to resolve this cencern and this HED has been closed.
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HED 2001 Communications - Paging System.
a ER0EQSED_ CORRECTION For each concern below, the following corttective actions are recommended:
Paging systems cannot be heard and/or understood in some areas (2001, 0283).
Provide loudspeaker with specialized functions to improve intelligibility.
Place them in appropriate designated areas.
Distortion in paging system and telephone system is not acceptable (2002, 2003).
j Provide intelligible and compatible paging and telephone systems.
A fast and reliable method of contacting auxiliary operators is required (2013).
Provide an efficient and reliable personnel paging system.
This HED is considered to have a partial correction because the proposed l-corrective actions are contingent upon the further in-depth study of the l
communication system recommended by the assessment-team in the report entitled, "A Preliminary Evaluation of the Communication System at the Sequoyah Nuclear Plant,-(July 1986)." The detailed design study will allow corrective act ions for t'm communication system to be implemented on an integrated basis.
BASJS FOR CIQSUKE iR.c basis for closure of the paging tystem HED is that the correction for plant radios (HED 2010) w111 provide new higher-wattage radios to assistant unit operators.
In addition, new battery chargers have been y rchased and the customer group is providing the Operations department with a program to properly maintain the batteries.
This action is the resolution of the results of a-test performed by the customer group on
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March _17, 1999., that identified inadequate radio battery maintenance as the root cause of the radio coverage problem.
These improvements to +.he L
plant radio system will provide acceptable communication to Operativas personnel in the plant and will eliminate the need to improve the plant paging-system. This alternate -corrective action for the concern on the plant paging system has been evait ated by experienced operstors and was found to be acceptable.
In summary, this HED has been closed based on the actions being implemented for the plant radio system.
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ENCLOSURE 4 i
- e IVA will provide NRC with the results of the evaluation of Sequoyah' V
Nuclear Plant human engineering deficiencies and the justification for deletions from the detailed control room design review resolu61on effort by-Febtuary;5. 1993.
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