ML20150C832
| ML20150C832 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/11/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20127A683 | List:
|
| References | |
| NUDOCS 8803220334 | |
| Download: ML20150C832 (19) | |
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UNITED STATES
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8 NUCLEAR REGULATORY COMMISSION n
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t WASHINGTON, D. C. 20555 o
'+4.....,o SE000YAH NUCLEAR POWER PLANT, UNITS 1 & 2 SAFETY EVALUATION REPORT FOR EMPLOYEE CONCERN ELEMENT REPORT 223.2, "INSTRUMENT MOUNTING BRACXETS" 1.
SUBJECT Category:
Engineering (EN)
Subcategory:
(ISD) i Element:
Instrument Mounting Brackets The basis for Element Report 223.2(B), dated May 6, 1987 is Employee Concern IN-85-973-002 which' states:
"Typical instrument mounting brackets consisting of thin gauge, perforated sheetmetal (or similar material) are not strong enough to support the instruments (generic for typical mounts).
Constant bumping into, leaning against, and sitting on these brackets or instruments causes damage to both brackets and instruments.
CI could not provide specific instrument numbers, locations, etc., but stated all such installations should be subject to re-design. This was reported to manager (known) but no action was taken."
This concern was evaluated by TVA as potentially nuclear safety-related and potentially applicable to Sequoyah (generic).
II.
SUMMARY
OF ISSUES Four issues were identified by TVA; the first three are evaluated in this report and the last is addressed in element report 706.1.
1.
Instrument mounting brackets are not strong enough to support instruments.
2.
In heavy traffic areas, the brackets are susceptible to abusive treatment which causes damage to brackets and instruments.
3.
All such installations should be redesigned.
4.
This deficiency was reported to the manager, but no action was taken.
III. EVALUATION Sequoyah's design criteria in FSAR 3.10 and SQN-DC-V-10.3 and 10.4 states that Category I instrumentation shall be designed and installed so that 8803220334 880311 DR ADOCK 0500 8
. normally imposed loads plus loads imposed by the design basis earthouake will not cause failure or functional degradation of the instruments or the 1
control systems.
The majority of the instruments at Sequcyah are found on floor-mounted panels, although wall-mounted panels are also used.
Typically these panels are a combination of Unistrut-type metal brackets, angles, and clips with metal plates for attaching the instruments.
The panel is normally welded and instruments and instrument lines are attached by bolting.
The panels are bolted to the floor or the wall, although welds are sometimes used in place of bolts.
Most of the Unistrut-type material is steel ranging in thickness from 3/32 in, to 1/8 in.
Brackets and plates 1/4 in, thick have also been used.
TVA identified the brackets and design details relevant to the employee concern. A sample calculation was made of the 1/8 in, thick bracket that supports Foxboro pressure transmitter No. E11GM.
The results of the evaluation confirmed the support was adequate for design loads.
TVA admits that instruments and brackets are not immune to abuse and it is plausible that sitting or leaning on the components or bumping into them may cause damage. As an example, there was damage to two instruments at Watts Bar Nuclear Plant in September 1985.
TVA subsequently made a decision to double the thickness of the brackets to 1/4 in.
TVA reviewed construction and engineering nonconformance reports and SCRs and interviewed the cognizant engineers, but did not identify any instance of reported damage to Category I instrument support brackets. TVA admitted that mistreatment could cause damage of the components and stated that this issue is an important plant maintenance issue, but it is not a design issue.
In a related issue involving installation details of locally-mounted instruments, TVA committed to performfng field walkdowns of all instrument panel frames supporting category I instruments.
If the walkdown discloses damaged brackets, they will be strengthened or protected.
Damaged instruments will be repaired or replaced.
In a separate decision, TVA DNE committed to compiling a list of safety-related instruments mounted on light-gage brackets similar to those identified in the employee concern.
DNE will identify locations of the instruments and consider their susceptibility in view of the general traffic pattern.
TVA will perform a walkdown and identify any discrepancies.
TVA will initiate corrective action for each deficiency and, where necessary, develop stronger mounting details for replacing the instrument brackets.
IV.
CONCLUSIONS The NRC staff believes that the TVA investigation of the concern was adequate and their resolution of the concern as described in eierent report 223.2(B)isacceptable. At Secuoyah, a sample calculation showed that the brackets were adequate for their design loads and no damaged
. 1 brackets were identified.
TVA identified mistreatrrent of components as an important plant maintenance issue.
They committed to performing field walkdowns of all instrument panel frames supporting Category I instruments as well as safety-related instruments mounted on light-gage brackets that.
are located in the general traffic pattern.
The NRC will be monitoring I
the adequacy of the implementation of the proposed corrective action through the use of inspections and audits.
Contact:
P. Cortland X28734 l
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SEQUOYAH NUCLEAR POWER' PLANT, UNITS l'& 2-SAFETY EVALUATION REPORT FOR EMPLOYEE CONCERNS ELEMENT REPORT 223.3-SQN "INSTRUNENT SUPPORT DESION, LOCAL INSTRUMENT SEISMIC QUALIFICATION" I.
Subject category: Engineering
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Subcategory: Civil / Structural Element: Instrument Support Design, Local Instrument Seismic Qualification Concerns: IN-85-886-N04 The basis for Element Report 223.3-SQN, Rev. 2, dated June 3, 1987, is a previous NRC concern related to IN-85-886-001 which arose from review of QTC files that questioned the seismic qualification of local instruments and their supports being installed using "good engineering judgment" and without performing seismic analysis.
This concern was evaluated by TVA as potentially nuclear saf ety-related for Sequoyah (generic).
II.
Summary of Issues The stated concerns as defined by TVA are: (a) local instruments were Installed based on "good engineering judgment;" (b) no seismic analysis was done for different types of installation of local instruments; and (c) no seismic analysis was done for local instruments.
,i III. Evaluation TVA personnel and consultants conducted a review of the seismic qualifi-cation documentation and a walkdown of the as-built conditions of three local instruments, i.e., a force balance pressure transmitter, a pressure transmitter, and a temperature-switch.
Their investigations concluded that issue (a) yas valid, that issue (b) was valid for field-mounted but not for panel-and rack-mounted instruments because panels and racks were normally q allfled by seismic analysis and/or testing, and that issue (c)
. vas not valid because local instruments were normally qualified by tests in lieu of analysis.
The NRC staff reviewed TVA's investigations by per-forming a walkdown of the plant and auditing the seismic qualification documentation for the three local instruments previously reviewed by TVA, and concurred with TVA's findings.
During their walkdown the NRC staff found that the identification tag on the temperature switch was 'issing.
m TVA confirmed that such concern with the missing identification tag would be addressed in Element Report 301.15.
To resolve the concerns in issues (a) and (b), TVA developed a corrective action plan (CAP) which included three pre-restart and one post-restart items.
The pre-restart CAP covered the FSAR Chapter 15 events instruments in SON Unit 2, and the post-restart CAP was for the remaining (i.e., non-FS.iR Chapter 15 events) safety-related 4
instruments in Unit 2 and for all safety-related instruments in Unit 1.
1 The pre-restart CAP was to (1) compile a list of all safety related instru-ments required for FSAR Chapter 15 events at SON Unit 2, (2) perform a drawing search and field inspection for each instrument identified in item (1), and (3) perform a seismic qualification documentation search for each instrument identified in iten (1).
For the post-restart CAP, TVA will perf orm the document search and field inspection for the remaining safety i - -
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related instruments at Unit 2 and all safoty related instrumonts at Unit
'l 1.
The NRC staf f found the scope of the CAP to be adequate, but could not assess the adequacy of TVA's implementation of. the pre-restart CAP because the implementation is not yet completed.
IV.
Conclusions The NRC staff reviewed TVA's investigation of the employee concern and the CAP developed by TVA to address the concern.
The NRC staff believes that the TVA investigation of the concern was adequate, and their reso-lutlon of the concern as described in Element Report 223.3-SON, Rev. 2, is acceptable provided the implementation of the pre-restart CAP is adequately-completed.
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SEQUOYAH HUCLEAR POWER PLANT, UNITS 1 & 2 SAFETY EVALUATION REPORT FOR EMPLOYEE CONCERNS ELEMENT REPORT 224.5-SON "RACEWAY SUPPORT DESIGN,. SUPPORT OF CABLES" Subject Category: Engineering Subcategory: Civi1[ Structural Element: Raceway Support Design, Support of Cables Concerns: HAS-86-005 The basis for Element Report 224.5-SON, Rev. O, dated November 20, 1987, is Sequoyah Employee Concern HAS-86-005 which questioned the seismic capa-bility of the non-supported Flamastic-covered cables in the spreading room that penetrate the walls and ceiling.
This concern was etaluated by TVA as potentially nuclear safety-related for Sequoyah.
II.
Summary of Issues The stated concern as defined by TVA is that the non-laterally supported Flamastic-covered cables in the cable spreading room which penetrate the walls and ceilings may not be seismically safe.
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!!!. Evaluation l
TVA personnel conducted a seismic shake table test program to assess the l
seismic integrity of representative vertical cable bundles.
The objective of the testing was to demonstrate that the as-built condition would be acceptable without field modifications.
Representative cable loadings and input motions. were used during the test program to assess the ability of the cables to perform their intended functions.
In addition, walkdowns of the existing condition in the field were performed to verify that the boundary conditions in the field were sufficiently represented by those in the testing, and to investigate other possible aspects related to the employee concern.
TVA concluded that the vertical Flamastic-covered cables in the cable spreading room which penetrate walls and ceilings are sels-mically adequate and that no corrective action is required.
To evaluate the validity of TVA's conclusion, the NRC staff performed'a walkdown of the cable spreading room and reviewed all perUnent documents including the seismic test report for the vertical cables.
The NRC staff found that the seismic test results were acceptable and that the boundary conditions in the field were adequately simulated in the testing.
In addition, based on the walkdown, the NRC staf f verified TVA's investigation regarding the existence of adequate structural elements at the ceiling penetrations of the cable spreading room that support the vertical cable drops.
The NRC staff therefore concurred with TVA's conclusion regarding the seismic l
adequacy of the vertical Flanastic-covered cable drops in the spreadir; toom.. -
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.IV.
Conclusions The NRC staff reviewed TVA's investigation of the employee cocern.
The NRC' staff believes that the TVA investigation was adequate, and that their conclusion regarding the concern as described in Element Report 224.5-30N, Rev. O, is acceptable.
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o SEQUOYAH NUCLEAR POWER PLANf, UNITS 1 & 2
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SAFETY EVALUATION REPORT FOR EMPLOYEE CONCERNS ELEMENT REPORT 225.0-SQN "BATTERY SUPPORT DESIGN" I.
Subject Category: Engineering Subcategory: Civil / Structural Element: Battery Support Design Concerns: XX-85-122-017 The basis for Element Report 225.0-SQN, Rev. O, dated April 6, 1987, is Sequoyah Employee Concern XX-85-122-017 which questioned the acceptability of not having tie downs for both Class 1E and non-Class 1E battteries and the acceptability of using Unistrut supports for the batteries.
l This concern was evaluated by TVA as potentially nuclear safety related and potentially applicable to Sequoyah (generic).
l l
i II.
Summary of Issues The stated concerns as defined by TVA are: (a) Class 1E and non-Class lE batteries are unacceptably supported since they have no tie downs; and (b) Unistrut supports are unacceptably used. _._.
III. Evaluation TVA stated that for non-Class 1E services it was not necessary, from a safety or economic viewpoint, to apply the same seismic design requirements as those for class 1E services.
Thus TVA concluded that non-Class lE batteries need not have vertical tie downs to accommodate seismic events and that the strut used in their racks is acceptable.
The NRC staff con-curred with TVA's conclusion that non-Class lE batteries need not be sub-jected to the seismic design requirements for Class 1E services and hence the existing design and installation is acceptable.
The Class lE batteries include the Gould 125V vital battery system (Bat-teries I to V), which is located in the auxiliary building at Elev. 749',
and the CsD 125V diesel generator battery system, which is located ~ in the diesel generator building at Elev. 722' (at grade).
Only the C&D battery system was installed with the batteries positively tied down to the racks.
The side rails of the racks are Unistrut members.
The top side rails are above the center of gravity of the batteries, thus preventing the battery from possibly tipping over during seismic events.
The batteries and racks were seismically qualified by testing.
In addition, the racks were sels-mically qualified by analysis.
To investigate the employee concern with the Class 12 vital batteries and racks, TVA personnel and consultants first inspected all Unistrut fasteners on the Gould vital batteries I to IV for proper installation.
Several bolting installations of Unistrut fasteners in each of the four battery rooms were identified as not meeting design requirements.
By means of analysis, however, TVA concluded that the identifitd deficiencies in the as-built bolting installations of Uni-strut fasteners vould not affect the structural integrity of the racks 1
for vital batteries I to IV during seismic events.
TVA personnel then inspected the Unistrut fasteners on all vital battery racks for proper bolt torque, and retorques all bolts not meeting the prescribed torque value.
Finally, TVA consultants performed a walkdown of the vital battery rooms I, II and V in the auxiliary building, and battery rooms lA-4 and 2A-A in the diesel generator building, to make a general comparison of the as-built battery installation with the installation drawings and seismic qualifications.
They identified-one discrepancy.
That is, while the racks were bolted to the shake. table in the seismic qualification testing
-l of all SON vital batteries, the racks in vital battery rooms I and II were velded to the base embedded plate.
However, TVA consultants confirmed the adequacy of such discrepancy in the installation of the base anchor for the racks in vital battery rooms I aand I1.
Based upon the investi-gations described above, TVA concluded that the Class 1E batteries were
' acceptably supported with and without the use of vertical tie downs, as evidenced b'y the seismic qualification testing, and that the vital battery racks were adequately quallfled by testing and analysis.
Thus, TVA con-cluded that both issues in the employee concern were not valid and that no additional corrective actions were required.
To evaluate TVA's investigations for the employee concern with the Class 1E batteries and racks, the NRC staff audited (1) battery rack drawings, (2) seismic qualification test reports for all vital batteries, including the test methodology, input motion, mounting of batteries and racks, and required floor response spectrum, (3) TVA calculations which verified the acceptance of the several deficient bolting installations of Unistrut fasteners identified for the racks in vital battery rooms I to IV, and (4) the TVA evaluations that confirmed the adequacy of the welded base 3
r anchor of the racks in vital battery rooms I and II.
Based on their eva-luations, the ERC staff found TVA's investigations for the Class lE bat-teries to be thorough and adequate.
The NRC staff therefore concutred with TVA's finding that the employee concern was not valid and hence no j
further pre-restart actions were required.
i I V.' Conclusions The NRC staff reviewed TVA's investigation of the employee concern.
The NRC staff believes that TVA's In'restigation was adequate, and that their I
conclusion regarding the concern as described in Element Report 225.0-s0N, Rev. O, is acceptable.
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o-SEQUOYAH NUCLEAR POWER PLANT, UNI 7S 1 & 2 SAFETY EVALUATION REPORT FOR EMPLOYEE CONCERNS
-ELEMENT REPORT 226.0-SON "SEISMIC INTERACTION DESIGN, DESIGN OF LIGHTING FIXTURE SUPPORTS" Subject Category: Engineering.
Subcategory: Civil / Structural Element: Seismic Interaction Design, Design of Lighting Fixture Supports Concerns: WI-85-100-023 The basis for Element Report 226.0-SON, Rev. 2, dated January 9, 1987, is Watts Bar Employee Concern WI-85-100-023 regarding lighting fixtures not being properly restrained and caged to prevent them from becoming free or svinging missiles during seismic events.
This concern was evaluated by TVA as potentially nuclear safety-related and potentially applicable to Sequoyah (generic).
i II.
Summary of Issues The stated concern as defined by TVA is that the lighting fixtures are not properly designed to prevent them from becoming free or svinging mis-siles which might damage, through seismic interactions, nearby Category i
I equipment during a seismic event..
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III. Evaluation i
Investigations by TVA personnel and consultants concluded that supports for lighting fixtures were adequately designed to prevent them from be-coming free missiles but the issue of lights becoming swinging missiles was valid.
The NRC staff performed a walkdown of the plant and audited a number of SQN dgcuments including design criteria, drawings, and justifi-cations of seismic interaction, in particular, seismic interaction with small instrument tubings.
Based on their evaluations, the NRC staff con-curred with TVA's finding that the issue of lighting fixtures becoming i
free missiles was not valid and the issue of lighting fixtures becoming potential swinging missiles was valid.
In addition, the NRC staff per-formed a second walkdown of the plant to re-evaluate five worst possible cases of potential seismic interaction of lighting fixtures with small instrument tubings, and found TVA's investigation of the seismic inter-action fot small instrument tubing to be adequate.
To resolve the issue of lighting fixtures becoming potential swinging missiles, TVA developed a corrective action plan (CAP) consisting of two pre-restart and one post-restart actions.
For the pre-restart CAP, the first action was to provide (a) a complete program to describe and control the seismic interaction l
evaluation for current and future design activities, (b) a technical basis for the internal TVA memo specifying the seismic interaction inspection criteria, and (c) a re-review for adequacy of the written technical justifi-cation of the existing revision to calculation CEB-CAS-214.
The second pre-restart CAP action was to provide a walkdown and evaluation of the safety related areas which were excluded from TVA's investigations prior to the development of the CAP.
The post-restart CAP requires a 100% walkdown of i
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.p.
e lighting fixtures to resolve deficient conditions and to eliminate discre-pancies between design drawings and criteria.
TVA's justification for this post-restart action as a non-restart item was provided in CAQR SQP-871519, Rev. O, which states that the possible loss of on-site power emer-gency lighting system will not affect the plant operability because ECN's L6287 and L5984 added Category I 8-hour emergency light packs in areas that must be manned f,or safe shutdown and, in addition, portabic lanterns have been supplied to the operations staff as part of the compliance to Section
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III.J of 10CFR50 Appendix R.
The NRC staff found the scope of the CAP and the non-restart-justification for the post-restart action to be acceptable.
The implementation of the pre-restart ^ CAP ltems were completed, but the adequacy of the implemention has yet to be reviewed by the NRC staff.
IV.
Conclusions f
The NRC staff reviewed TVA's investigation of the employee concern and'the CAP developed by TVA to address the concern.
The NRC staff believes that the TVA investigation of the concern was adequate and their resolution of the concern with lighting fixtures at SQN becoming potential swinging missiles, as described in Element Report 22600, Rev. 3, is acceptable i
provided the implementation of pre-restart CAP is adequate.
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o SEQUOYAH NUCLEAR POWER PLANT, UNITS 1 & 2 SAFETY EVALUATION REPORT FOR EMPLOYEE CONCERNS ELEMENT REPORT 228.0-SON
- "UNISTRUT SUPPORT DESIGN" I.
Subject Category: Engineering Subcategory: Civil / Structural Element: Unistrut Support Design Concerns: XX-05-122-033 i
The basis for Element Report 228.0-SQN, Rev. 2,. dated January 26, 1987, is Sequoyah Employee Concern XX-85-122-033 which questioned th$'accepta-bility of using Unistrut material as seismic Category I supports for in-struments, pipes, conduits, control stations and panels, lighting, etc.
1 such that the supported ite::s will not f all or become missiles to damage other safety-related equipment.
This concern was evaluated by TVA as potentially nuclear safety-related fer Sequoyah (generic).
II.
Summary of Issues The stated concerns as defined by TVA are: (a) Unistrut is unacceptable for use as seismic Category I supports for instruments, pipes, conduits, control stations, panels, lighting, etc.; and (b) items so supported by Unistrut nay become missiles ant" endanger other safety-relatd equipment if the support fails... - - -..,.
!!I. Evaluation
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To address the Employee Concern XX-85-122-C33, TVA initially completed a sampling program for bolt tightening of Unistrut claaps and performed the necessary evaluations.
They then issued a new torque requirement for Uni-strut clamp bolts and committed to a' lor,g term bolt tightening program.
As a result of their investigation, TVA concluded that Unistrut materials are acceptable for use in supporting seismic category I conduits, tubing, pipe, etc.; however, two design deficiencies were found: (1) inccasistency in slip-through capacity of Unistrut p2558 series of clamp, size 2" to 4",
between TVA Singleton Laboratory and Unistrut Corp test results, and (2) unsubstantiated design of a double cantilevered conduit hanger in which the Unistrut p1000 member may be overstressed due to torsion.
To resolve i
the design deficiencies, TVA developed a corrective action plan (CAP) con-sisting of both pre-restart and post-restart actions.
To implement the pre-restart corrective actions, TVA (1) re-tested the slip-through capacity of the Unistrut p2558-20 to 40 clamps, in which the new results were con-sistent with the Unistrut Corp. test results, (2) revised the coreaponding slip-through allovables specified in TVA's pipe Support Design Manual (pSDH), and (3) verified the adequacy of the affected existing in-place supports on the basis of a "fit for service" criteria.
Through extensive valkdowns, TVA also verified that the double cantilevered hanger inquestion has not been installed in the plant.
I For d.e post-restart cap, TVA will confirm the adequacy of the Unistrut P-2558 series of clamps in the exisitng designs and installed conduit sup-ports based on the revised pSDM requirements, and provide fixes as needed.
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The NRC staff performed a walkdown of'the plant and audited TVA's previous investigations of the e,mployee concern as well as samples of TVA's implemen-tation of the pre-restart CAP.
The results of TVA's re-test of the slip-through capacity of the Unistrut P2558-20 to 40 clamps were found acceptable and TVA's verification that no double cantilevered conduit hanger has been installed in the plant was fcund reasonable.
The NRC staff therefore con-cluded that TVA's investigations of the concern and implementation of the pre-restart CAP were adequate.
The NRC staff also found the scope of the post-restart CAP sufficient.
8 IV.
Conclusions The use of Unistrut materials for seismic Category I supports, with proper design and installation, has been acceptable to the NRC staf f in other licensed plants.
The NRC staf f reviewed TVA's investigations and implemen-tation of corrective actions, and believes they are adequate as pre-restart resolution of the concern described in Element Report 228.0-SQN, Rev. 2.
The NRC staf f also f ound the scope of the post-restart CAP acceptable.
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