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LER 80-091/01X-0:on 801223,IE Bulletin 80-11 Analysis Determined That Listed Walls Between Control Room & Stairway AB-1 Would Be Overstressed During Seismic Event.Caused by Outdated Analytical Methodology Used by A/E
	ML20010G303
Person / Time
Site:	Davis Besse
Issue date:	09/02/1981
From:	Mekbel C; TOLEDO EDISON CO.
To:	; NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20010G297	List: ML20010G296; ML20010G303; ML20010G307;
References
	IEB-80-11, LER-80-091-01X, LER-80-91-1X, NUDOCS 8109150555
	Download: ML20010G303 (13)
	v • d • e

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. 8 60 68 DOCAET NUUSER EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 10121 l (NP-32-80-17) The analysis required by NRC IE Bulletin 80-11 determined that durine a j the wall between the control room and stairway AB-1, walls 3307, 2047, I 10131l seismic event I

@ l 3167, 3187, 2337, 4806, 4817, 4826, 4837, 4847, 4857, 4647, 4016, 3407, 5207. 2297, 82 E l 4796, 4886, 4896, and a portion of 311D would be overstressed. Walls 3167, 3177, 3187j would be overstressed by compartment l Q l 4107, 4117, 4127, 3447, 3457, 3467, 3237, 3287 l 0 l 7 l l pressurization. The conditions are reportable per Technical Specification 6.9.1.8.1.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-80-17 DATE OF EVENT: December 23, 1980, February 17, March 10, March 27, April 21, May 7, May 13, June 11, June 12, June 29, July 29, August 5, August 11 and August 20, 1981.

FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Floor beam at the top of concrete block wall 5107, the floor beam at the top of concrete block wall 3307, the connection between concrete block wall 2047 and the floor, the connec-tion between wall 2337 and the floor, and floor beams at the top of walls 3167 and 3187 would be overstressed during a design basis seismic event. Walls 3167, 3177 and 3187, and walls 4107, 4117 and 4127 would be overstressed during a compartment pressurization. Walls 3447, 3457 and 3467 could fail during a seismic event or experience masonry over-stress following pressure loadings resniting from compartment pressuri-zation. Walls 4806, 4817, 4826, 4837, 4847 and 4857 could fail and wall 4647 could experience localized wall overstress during a seismic event.

The stresses in the masonry and in the top and bottom connections in wall 4016 could exceed design allowable stresses during a seismic event.

Connections of walls 3237 and 3287 could become overstressed when subjected to pressure loading resulting from a main feedwater line break.

The floor beam connected to the top of wall 3407 would be overstressed during a seismic event.

The floor beam connected to the top of wall 5207 and the masonry and expansion anchors on a portion of the east edge of wall 311D could become overstressed during a seismic event.

The floor beam connected to the top of wall 2297 and the edge connections 12 of walls 4796, 4886 and 4896 could become overstressed during a seismic event.

CONDITIONS PRIOR T3 OCCURRENCE: The unit was in Mode 1 with Power (MWT) = 1525 and Loa. (Gross MWE) = 289.

DESCRIPTION OF OCCURRENCE: While performing the analysis of concrete block walls required by NRC IE Bulletin 80-11, it was determined that during a seismic event the block wall between the control room and stair AB-1 would cause the floor beam above to be overstressed. This floor beam is attached to the wall and supports a portion of the floor above the control room.

It was determined that this condition was less conservative than assumed in the Final Safety Analysis Report (FSAR) and is being reported under Technical Specification 6.9.1.8.1. The NRC On-Site Inspector was notified at 0925 hours0.0107 days 0.257 hours 0.00153 weeks 3.519625e-4 months on December 23, 1980.

LER #80-091 E 4

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Additional analysis per NRC IE Bulletin 80-11 determined that during a seismic event the block wall between component cooling water heat exchanger and pump room (#328) and elevator number 2 would cause the floor beam above to be overstressed. This floor beam is attached to the wall and supports a portion of the floor above the component cooling water exchanger and pump room.

It was also determined that this condition was less conservative than assumed in the FSAR and is being reported under Technical Specification 6.9.1.8.1. The NRC On-Site Inspector was notified at 0935 hours0.0108 days 0.26 hours 0.00155 weeks 3.557675e-4 months on February 18, 1981.

Additional analysis per NRC IE Bulletin 80-11 determined that during a seismic event, the loads on block wall 2047 (between the two makeup pumps) from the attached piping systems would cause the stresses in the connection between the wall and the floor to be greater than code allow-ables.

It was determined that this condition was less conservative than assumed

' in the FSAR and is being reported under Technical Specification 6.9.1.8.i.

The NRC On-Site Inspector was notified at 1221 hours0.0141 days 0.339 hours 0.00202 weeks 4.645905e-4 months on March 11, 1981.

Analysis of additional walls per NRC IE Bulletin 80-11 determined that during a seismic event, walls 3167 and 3187 would cause the floor beams attached to the tops of these walls to become overstressed. It was also determined that the concrete masonry in block walls 3167, 3177 and 3187 >

would be overstressed when subjected to compartment pressurization originating from a pipe break. These walls form a cable chase in Mechan-ical Penetration Room #4 (Room 314) on the 585 foot elevation.

This condition was less conservative than assumed in the FSAR and is i being reported under Technical Specification 6.9.8.1.1. The NRC On-Site Inspector was notified at 1325 hours0.0153 days 0.368 hours 0.00219 weeks 5.041625e-4 months on March 30, 1981.

Additional analysis per NRC IE Bulletin 80-11 determined that during a design basis seismic event, the connection between wall 2337 and the floor could become overstressed. This wall is located in Mechanical i Penetration Room #2 on the 565 foot elevation.

It was determined that this condition was less conservative than assumed j

in the FSAR and is being reported under Technical Spccification 6.9.1.8.i.

l The NRC On-Site Inspector was notified at 1204 hours0.0139 days 0.334 hours 0.00199 weeks 4.58122e-4 months on April 22, 1981.

Additional analysis per NRC IE Bulletin 80-11 determined that after a main feedwater pipe break, the increase in pressure created could develop an overstressed masonry condition in block walls 4107, 4117 and 4127.

These walls located on elevation 603'-0" form a pipe chase in corridor 404.

It was determined that this condition was less conservative than assumed in the FSAR and is being reported under Technical Specification 6.9.1.8.i.

The NRC On-Site Inspector was notified at 1530 hours0.0177 days 0.425 hours 0.00253 weeks 5.82165e-4 months on May 7, 1981.

i LER #80-091 l 2

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Additional analysis per NRC Bulletin 80-11 determined +het during a seismic event, loadings are imposed on walls 3447, 3457 and 3467 whi-h could cause localized wall failure. It was also determined that these walls, which separate corridor 304 from corridor 310 and room 313 on floor elevation 585'-0" could also become overstressed when subjected to compartment pressurization originating from a main feedwater line break.

It was determined that this condition was less conservative than assumed in the FSAR and is being reported under Technical Specification 6.9.1.8.1.

The NRC Region III office was notified at 1040 hours0.012 days 0.289 hours 0.00172 weeks 3.9572e-4 months on May 14, 1981.

Additional analysis received June 11, 1981 per NRC Bulletin 80-11 deter-mined that during a seismic event, loadings are imposed on walls 4806, 4817, 4826, 4837, 4847 and 4857 which could cause the walls to fail (fall ovar). These walls serve as fireproofing for building columns located in Electrical Penetration Room No. 2 (room 427, elevation 603').

It was determined that this condition was less conservative than assumed in the FSAR and is being reported under Technical Specification 6.9.1.8.i.

The NRC On-Site Inspector was notified at 1400 hours0.0162 days 0.389 hours 0.00231 weeks 5.327e-4 months on June 12, 1981.

Addit.'onal analysis received June 12, 1981 per NRC IE Bulletin 80-11 determined that during a seismic event, loadings are imposed on wall 4647 which could create a localized masonry overstressed condition.

This wall is a firewall and part of the negative pressure boundary separating the cable spreading room at elevation 613'-6" from corridor 404 at elevation 603'-0".

It was determined that this condition was less conservative than assumed in the FSAR and is being reported under Technical Specification 6.9.1.8.i.

The NRC On-Site Inspector was notified at 1530 hours0.0177 days 0.425 hours 0.00253 weeks 5.82165e-4 months on June 15, 1981.

Additional analysis per NRC Bulletin 80-11 determined that during a seismic event, the masonry and wall connections in wall 4016 could become overstressed. This wall separates the low voltage switchgear room (No. 428) from Battery Room B (No. 428A) on Elevation 603 in the Auxiliary Building. It was determined that this condition was less conservative than assumed in the FSAR and is being reported under Technical Specification 6.9.1.8.i. The NRC On-Site Inspector was notified at 1500 hours0.0174 days 0.417 hours 0.00248 weeks 5.7075e-4 months on June 30, 1981.

Additional analysis per NRC I.E.Bulletin 80-11 determined that after a crack in the main feedwater line located in Room 313, the increase in pressure created could develop overstressed conditions in the expansion anchors in the connections at the south end of wall 3287 and the north end of wall 3237. Additionally, the floor beam at elevation 603'-0" to which the top of wall 3237 is connected could be overstressed in torsion when the wall is subjected to such a loading. Wall 3237 separates elevator No. 3 from Passage 310 and wall 3287 separates stairway AB-2 from Passage 310, on elevation 585'-0".

LER #80-091 3

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It was determined that this condition was less conservative than assumed in the F.S.A.R. and is being reported under Technical Specification 6.9.1.8.1. The NRC On-Site Inspector was notified at 1330 hours0.0154 days 0.369 hours 0.0022 weeks 5.06065e-4 months on July 30, 1981.

Re-analysis of masonry block walls required by NRC IE Bulletin 80-11 determined that during a seismic event, wall 3407 could cause the floor beam attached to the top of this wall to become overstressed. This wall located on floor elevation 585' separates the component cooling water heat exchanger and pump room (#328) from stairway AB-1.

It was also determined that this condition was less conservative than assumed in the FSAR and is being reported under Technical Specification 6.9.1.8.1. The NRC on-site inspector was notified at 1400 hours0.0162 days 0.389 hours 0.00231 weeks 5.327e-4 months on August 6, 1981.

Re-analysis of masonry block walls required by NRC IE Bulletin 80-11 determined that during a seismic event, wall 5207, separating the computer room (#510) from control cabinet room (#502), elevation 623, could cause the floor beam attached to the top of this wall to become overstressed.

It was also determined that wall 311D, on elevation 585 in the Diesel Generator Room (#318), could experience a localized overstressing of masonry and expansion anchors under a seismic loading.

It was found that these conditions were less conservative than assumed in the FSAR and is being reported under Technical Specification 6.9.1.8.1.

The NRC on-site inspector was notified at 1447 hours0.0167 days 0.402 hours 0.00239 weeks 5.505835e-4 months on August 12, 1981.

Re-analysis of concrete. masonry block walls required by NRC I.E.Bulletin 80-11 determined that during a seismic event, wall 2297 could cause the floor beam attached to the top of this wall to become overstressed.

This wall, located on elevation 565', separates Boric Acid Evaporator Rooms 234 and 235. Additionall';, it was determined that the top connections 12 of walls 4796, 4886 and 4896 and the bottom and east edge connections of wall 4886 could become overstressed during a seismic event.

It was determined that these conditions were less conservative than assumed in the F.S.A.R. and are being reported under Technical Specification 6.9.1.8.i. The NRC on-site inspector was notified at 1450 hours0.0168 days 0.403 hours 0.0024 weeks 5.51725e-4 months on August 21, 1981.

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DESIGNATION OF APPARENT CAUSE OF OCCURRENCE: This finding is due to a change in the analytical methodology used by the architect / engineer since the walls were designed in the early 1970's. Using the methods applicable at that time, the floor beam would be acceptable as built.

However, the change in the method treats wall section properties and seismic floor response inputs differently and is a dynamic instead of static analysis. Under the new methods, the floor beam design and the wall to floor connection is deficient.

For the seventh finding, the cause of the occurrence resulted from architect / engineer design error. Wall to lintel (support beam over door 309) connection associated with walls 3447, 3457 and 3467 was originally deficient in design when subjected to seismic loading.

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Compactment pressures generated by postulated pipe breaks were not originally considered when the architect / engineer designed the walls.

Re-analysis of these walls with the additional loading has resulted in the overstressed masonry condition.

For the eighth and ninth findings, the cause was an architect / engineer design error which resulted in the construction of walls 4806, 4826 and 4647 across a seismic joint leading to wall strength deficiencies when subjected to seismic loadings. Additionally, when walls 4806 and 4826 were originally designed, the loads from wall attachments were not coasidered. Subsequent analysis using dynamic instead of static methods and including wall attachment loadings resulted in an overstressed wall condition during a seismic event.

The finding on wall 4016 is the rerilt of a change in the analytical methodology used by the architect / engineer since the wall was originally designed. Additionally the loads from wall attachments were not origi-nally considered. Subsequent analysis using dynamic instead of static methods and wall attachment loadings resulted in an overstressed wall condition during a seismic event.

For walls 3237 and 3287 compartment pressures generated by a main feed-water line break were not originally considered when Architect / Engineer designed the walls.

The finding for wall 3407 is due to a change in the analytical method-ology used by the architect / engineer since the walls were designed in the early 1970's. Using the methods applicable at that time, the floor beam would be acceptable as built. However, the change in the method treats wall section properties and seismic floor response inputs differ-ently and is a dynamic instead of static analysis. Under the new methods, the floor beam design is deficient.

The finding for 5207 and 311D is due to a change in the analytical methodology used by the architect / engineer since the walls were designed in the early 1970's. Using the methods applicable at that time, the floor beam and wall connections would be acceptable as built. However, the change in the method treats wall section properties and seismic floor response inputs differently and is a dynamic instead of a static analysis. Under the new methods, the floor beam above wall 5207 and the masonry and wall connections associated with wall 311D are deficient.

The finding for walls 2297, 4796, 4886 and 4896 is due to a change in 12 the analytical methodology used by the architect / engineer since the walls were designed in the early 1970's.

ANALYSIS OF OCCURRENCE: There was no danger to the health and safety of the public or station personnel. The floor beams and wall to floor connection in question are only overstressed during a maximum probable earthquake. During all other postulated unit operating conditions, the stresses are within allowables.

LER #80-091 5

r A preliminary review of the portion of the floor above the control room supported by chis beam has been made. The results are not conclusive but indicate there is a potential that a portion of the floor above may undergo some structural distress. A more detailed analysis would take three months to perform. The modification to correct this condition consists of two small struts which could be installed in about two weeks. Therefore, in the interest of taking the most expeditious approach, Toledo Edi.on has decided to make the modification at this time without proceeding with further analytical effort.

Similarly, a preliminary review of the portion of the floor above the component cooling water heat exchanger and pump room supported by the beam has been made. The results are not conclusive but indicate there is a potential that a portion of the floor above may undergo some struc-tural distress. A more detailed analysis would take three months to perform. The modification to correct this condition consists of the installation of three plate stiffeners betweer the web of the floor beam and the floor above. This modification can be made in a shorter time than it would take to complete the detailed analysis of the floor.

Therefore, in the interest of taking the most expeditious approach, Toledo Edison has decided to make the modification at this time without proceeding with the detailed floor analysis.

Pipe supports 31-HCC-5H5, 31-HCC-5H6, 31-HCC-5H7 and 31-HCC-SH9 are attached to wall 2047. During a maximum probable earthquake thuce pipe supports impart loads to wall 2047 which causes the stresses in portion of the connection between wall 2047 and the floor to be greater than allowed by the Uniform Building Code (UBC) and American Concrete Institute (ACI) Code. The wall was analyzed as five wall strips. The stresses in the connection between the wall and the floor in only two of the wall strips were greater than allowable. However, even in these two strips, the factors of safety are greater than one, demonstrating that these strips are still stable.

'There is also an inherent conservatism in our analysis since the inter-action between wall strips is not considered.

The piping systems attached to the wall have been reanalyzed assuming i that there will be deflection in wall 2047. The resulting piping and support stress are all within the interim allowable stresses developed for IE Balletin 79-14.

Overstress of the masonry comprising block walls 3167. 3177 and 3187 is due to the postulated compartment pressure resulting from a break in the main feedwater line in room 314. During all other operating conditions, the stresses are within allowables. However, such a break in this room has a low probability of occurring. The portion of the pipe meets most of the criteria established by NRC Branch Technical Position MEB 3-1 to l

qualify as a "no break zone", the exception being that the piping was designed to ANSI B31.1 instead of ASME Se, tion III, Class 2. However, the Toledo , Edison procurement and Ir+ a11ation specifications required the same material and installation documentation as is required under ASME Section III, Class 2.

LER #80-091 6

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The effects of the wall deflection caused by the seismic loads on nuclear safety related conduit attached to these walls have been investigated and failure of the conduit will not occur. Additional analysis to determine if yielding of the floor beams would cause structural distress in a portion of the floor above would take approximately six menths to perform, while a modification to ensure the condition is conservative can be made in a shorter time.

In the case of wall 2337, the stresses created in the wall to the floor connection are greater than criteria allowables per the Uniform Building Code (UBC) and the American Concrete Institute (ACI) Code. However, the factor of safety on the connection was still greater than 1, thus demon-strating wall stability during a seismic event.

1 The stresses in the piping and conduit sys? ems attached to this wall have been reviewed assuming the wall would deflect during a seismic event, and found to be within allowable limits.

When a break in the main feedwater line in corridor 404, including the portion within the pipe chase is postulated, the masonry in walls 4107, 4117 and 4127, and all wall connections, could become overstressed due to the pressure loading. During all other postulated unit operating conditions, the stresses are within allowable limits.

The above postulated event (a main feedwater pipe break in corridor 404) has a low probability of occurrence. The affected portion of the main feedwater line has been reviewed against current design criteria. Our review indicates that this piping meets the requirements of Branch Technical Position MEB 3-1 (Section B.1.b) for Fluid System Piping in containment penetration areas where break need not be postulated, with the following exceptions: 1) the piping system was designed to ANSI B31.1 instead of ASME Section III, Class 2. However, the Toledo Edison procurement and installation specifications required the same material and installation documentation as is required under ASME Section III, Class 2; and, 2) this portion of the piping does not comply with Section Bl.lb(4) which requires that the length of the section of pipe for which breaks are not postulated be kept to a minimum.

During a seismic event, walls 3447, 3457 and 3467 could experience localized wall failure. Sections of these walls, if allowed to fail,

! could possibly impact the safety related conduits penetrating the walls, although further analysis would be required to analyze how the conduits would be affected. A partial modification to correct this condition has been designed and can be implemented more expeditous'.y than the time required for further analysis.

l j Additionally, the masonry comprising block walls 3447, 3457 and 3467 l could become overstressed following the postulated compartment pressure

! resulting from a break in the main feedwater line in either room 313 or f corridor 304. During all other operating conditions, the stresses are within allowables. However, such a break in this room has a low proba-bility of occurring. The portion of the pipe meets most of the criteria LER #80-091 l

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established by NRC Branch Technical Position MEB 3-1 to qualify as a "no break zone" with the exceptions being: 1) the piping was designed to However, the Toledo ANSI B31.1 instead of ASME Section III, Cless 2.

Edison procurement and installation specifications required the same material and isntallation documentation as is required under ASME Section III, Class 2; 3) the piping in room 313 or corridor 304 does not comply with Section Bl.1B(4) which requires that the length of the section of pipe for which breaks are not postulated be kept to a minimum.

Following a maximum probable earthquake, walls 4806, 4817, 4826, 4837, 4847 and 4857 could experience loss of structural strength due to wall attachment loadings and potential differential movement between seismic zones #6 and #7. Failure to construct a seismic joint in walls 4806, 4826, 4837 and 4857 between these zones contributes to their failure and that of walls 4817 and 4847.

A potential consequence of wall failure could be damage to the safety related conduits attached to these walls and possible damage to safety related items in the room adjacent to these walls. The degree of damage However, if the to these conduits has not conclusively been determined.

circuits contained within the damaged conduits are affected such that they cannot perform their designed function, safeaffected.

shutdown of the plant could still be provided by alternate systems not Failure to provide a seismic joint at the south end of masonry wall 4647 could create a localized overstressed masonry condition in this wall.

The masonry is overstressed in compres.sion due to in plane seismic loads Localized crushing of the generated by the absence of this joint.

masonry in the vicinity where the joint should have been constructed, This localized masonry crushing should not could occur as a result.

result in the loss of function of the safety related circuits contained within the conduits penetrating this wall for the following reasons:

1) the loadings on the steel conduits are reduced due to energy dissipa-tion when localized masonry crushing occurs; 2) radial compressive strength of the steel conduits is greater than the compressive strength of the masonry; and, 3) support for safety related conduits which pene-trate tha wall will not be affected.

When wall 4016 is subjected to a seismic loading, the masonry stresses in the wall and the stresses in the top and bottom wall connections exceed design allowables. Additionally deflection during a seismic event of the wall would cause attached conduits, some of which contain to exceed the acceptance criteria for nuclear safety related circuits, Failure of the entire wall or circuits contained the conduit deficction.

within the affected conduits has not been confirmed even though the allowable stress has been exceeded. The present analysis uses average material strengths and does not take any credit for load reductions If, however, attributable to localized failure (crushing) of masonry.

in the unlikely event that the nuclear safety related circuits contained within the affected conduits cannot perform their intended safety function, safe plant shutdown could still be provided by alternate systems not affected.

LER #80-091 0

During a postulated break in the main feedwater line in Room 313 the expansion anchors in the connections in walls 3237 and 3287 and the floor beam attached to the top of wall 3237 could become overstressed.

A potential consequence could be structural distress in a portion of the floor above the beam at elevation 603'-0". Further analysis would be required to determine if this portion of the floor would becomo over-stressed if yielding of the beam did occur. A modification to correct this condition can be designed and implemented more expeditiously than the 2 to 3 months required for a detailed analysis of the floor system.

Also, failure of the wall connections is not likely even though the factors of safety for the expansion anchors in the connections are less than the acceptance criteria. However, this factor of safety is greater than 2, specified as acceptable for short term operability by I.E.

Bulletin 79-02.

Additionally, a pipe break of this nature in Room 313 has a low probability of occurring. The portion of the pipe meets most of the criteria estab-lished by NRC Branch Technical Position MEB 3-1 to quality as a "no-break zone" with the exceptions being: 1) the piping was designed to ANSI B 1.1 instead of ASME Section III, Class 2. However, the Toledo Edison procurement and installation specifications required the same material and installation documentation as is required under ASME Section III, Class 2; 2) the piping in Room 313 does not comply with Section B.1.b (4), which requires that the length of the section of pipe for which breaks are not postulated be kept to a minimum.

When wall 3407 is subjected to seismic loadings from a maximum probable earthquake, the floor beam attached to the top of the wall could become overstressed. A preliminary review of the portion of the floor above the component cooling water heat exchanger and pump room indicates that there is a possibility that a portion of the floor above may undergo some structural distress. A more detailed analysis to verify this possibility would require two to three months to perform. The modifi-cation to correct this condition consists of structurally bracing the beam which could be accomplished in a shorter time than it would take to complete a detailed analysis of the floor system. Therefore, in the interest of taking the most expeditious approach, Toledo Edison has decided to make the modification at this time without proceeding with the detailed floor analysis.

When wall 5207 is subjected to seismic loadings from a maximum probable earthquake, the floor beam attached to the top of the wall could become overstressed. A preliminary review of the portion of the floor above indicates that there is a possibility that a portion of the floor may undergo some structural distress. A more detailed analysis to verify this possibility would require three months to perform whereas a modifi-cation to correct this condition could be accomplished in a shorter time. Therefore, in the interest of taking the most expeditious approach, Toledo Edison has decided to make the modification at this time without further analytical effort.

LER #80-091 9

Also, during a seismic event, wall 311D could experience localized failure. The area affected would be limited to a four foot long strip along the eastern wall edge. At one location the masonry is overstressed in shear and the expansion anchors have factors of safety less than one.

Because the indicated failure is local, gross wall failure is not expected to occur. Additionally, because of inherent strengths in the wall not considered, conservative assumptions in the analysis, and that the wall is reinforced, damage to safety related items in the immediate vicinity of the wall resulting from spalled masonry is considered remote.

When wall 2297 is subjected to a seismic loading, the floor beam attached to the top of wall 2297 could become overstressed. A preliminary review of the floor above Boric Acid Evaporator Rooms 234 and 235 indicates that there is a possibility that a portion of the floor may undergo some structural distress. A modification to correct the condition can be implemented more expeditiously than the time required for further analysis.

Additionally, during a seismic event, the welds fastening plates to the underside of the metal floor deck for the top connection of walls 4796, 12 4886 and 4896 are stressed beyond allowable limits. The bottom and east edge expansion anchors of wall 4886 are also stressed beyond allowable limits but exhibit factors of safety greater than 1.0. Wall failure is not expected as a result of the overstressed top connections because

1) wall bond or friction at the bottom and side connections was not considered and 2) arching effects of the wall would tend to lower the stress on the connections.

CORRECTIVE ACTION: Under Facility Change Request 80-277, two struts were added to the floor. beam above the wall between the control room and stairway AB-1. This work was completed March 6,1981.

l For the second finding, three plate stiffeners will be installed between the beam and floor above, under Facility Change Request 81-015.

I For the third finding, the condition will be corrected by removing the l pipe supports from wall 2047 and attaching them to the makeup pump room ceiling. This relocation work will be done under Facility Change Request 81-016 when station operating conditions permit.

l For the fourth finding, the condition will be corrected by the addition

! of a two-layered internal bracing system to the cable chase formed by j walls 3167, 3177 and.3187. The top layer of bracing will lower the j floor beam stresses to allowable limits by reducing the wall deflec-tions. The lower level internal bracing will reduce the masonry wall l

stresses (these caused by compartment pressurization) to within allow-l ables. These modifications will be made under Facility Change Request 81-018 when station operating conditions permit.

f LER #80-091 l

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For the fifth finding, the condition will be corrected by reinforcing the connection of the base of wall 2337 by adding steel angles connected to the wall and floor with thru-bolts and expansion anchors. This modi-fication will be made under FCR 81-017 when station operating conditions permit.

For the sixth finding, the condition will be corrected by the removal of walls 4117 and 4127, and replacement of wall 4117 with a steel jet impingement shield. Wall 4107 will be reinforced with u steel post anchored to the floor. This modification will be made under Facility Change Request 81-020 when station operating conditions permit.

For the seventh finding, Facility Change Request 81-019 has been issued for immediate implementation. This FCR will reduce the stress in the wall caused by a seismic event and compartment pressurization to within allowable limits. The initial portion of this FCR work will reduce the stresses caused by a seismic event. A supplement will be issued to also reduce the stresses caused by compartment pressurization and further refine the seismic portion of the modification.

For the eighth finding, the ceadition will be corrected by removing walls 4806, 4817, 4826, 4837, 4847 and 4857, fireproofing the buildir4 columns which were surrounded by the walls and relocating the existing wall attachments to satisfactory supports. This modification will be made under Facility Change Request 81-021 when station operating condi-tions permit.

The condition of wall 4647 will be corrected by constructing the required seismic joint in this wall per Facility Change Request 81-022 when station operating conditions permit.

The condition of wall 4016 will be corrected by removing 16" wide block sections at six locations for the full height of the wall and replacing them with steel box sections fastened to the floor below and floor beams above this wall. This modification will be made under Facility Change Request 81-023.

The condition of walls 3237 and 3287 will be corrected by bracing the floor beam to resist the loading from wall 3237 and reinforcing the south end connection of wall 3287 and the north end connection of wall 3237 with angles and expansion anchors. This modification will be made under Facility Change kequest 81-024.

Bracing will be added at four locations to the beam above wall 3407.

This modification will be performed under Facility Change Request 81-025.

The condition of wall 5207 will be corrected by bracing the floor beam i above to resist the loading from wall 5207. This will be done under Facility Change Request 81-027.

The eastern edge of wall 311D will be strengthened by the addition of a pilaster to the wall at this location. This modification will be made under Facility Change Request 81-026.

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i i The condition of the floor beam above wall 2297 will be corrected by bracing the beam with steel struts under Facility Change Request 81-031. The condi-

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i 12 tion of walls 4796, 4886, and 4896 will be corrected under Facility Change Request 81-028 which will consist of adding steel angles and expansion ,

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anchors to reinforce the top, bottom, and east edge connections.

1 Failure Data: The;e have been no previously similar reported occurrences.

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ML20010G303

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