ML18038A553

Forwards Info Provided at 810306 Meeting W/Nrc to Discuss Unstaggered Splices Re Dywidag Threadbear Sys.Approval by 810331 Requested to Use Sys in Unstaggered Applications Subj to Described Limitations & Conditions

ML18038A553
Person / Time
Site:	Nine Mile Point
Issue date:	03/18/1981
From:	Dise D NIAGARA MOHAWK POWER CORP.
To:	Youngblood B Office of Nuclear Reactor Regulation
References
NUDOCS 8103240374
Download: ML18038A553 (22)

Text

I e REGULATE INFORMATION DISTRIBUTION+'STEM (RIDS)

ACCESSION NBR 8103240374 e DOC, DATE 81/03/18 0 NOTARI2ED! NO DOCKET e FACIL:50-010 BYNAME Nine Mile Point Nuc'lear Station, Unit 20 Niagara Moha 05000010 AUTH AUTHOR AFFILIATION D

DISEUR ~ P ~ Niagara Mohawk Power Corp.

RECIP NAME RECIPIENT AFFILIATION YOUNGBLOODEB,J, Licensing Branch 1

SUBJECT:

Forwards info provided at 810306 meeting w/NRC to splices re DYNIDAG Threadbear Sys Approval by

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discuss'nstaggored 810331 requested to use sys in unstaggered applications subjt to described limitations 8 conditions.

DISTRIBUTION CODE: 0001S COPIESRECEIVED:LTR (. ENCL g SIZ 5:

TITLE". PSAR/FSAR AMDTS and Related Correspondence NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID LTTR ENCL ID CODE/NAME LTTR ENCL A/D LICENSNG CODE/NAME'CTION:

1 0 YOUNGBLOODgB 1 0 RUSHBROOKFM ~ 1 0 KIPERFKa 04 1 1 INTERNAL: ACCID EVAL BR26 1 1 AUX SYS BR 07 1 1 CHEM ENG BR 08 1 1 CONT SYS BR 09 1 1 CORE PERF BR 10 1 1 EFF TR SYS BR12 1 1 EMERG PREP 22;, 1 0 EQUIP QUAL BR13 3 GEOSC IENCES 14 1 1 HUM FACT ENG BR 1 1 HYD/GEO BR 15 2 2 I8C SYS'R 16 1 I 8 EI 06 3 3 LIC GUID BR 1 1 LIC, QUAL BR 1 1 MATL ENG BR 17 1 1 MECH ENG BR 18 1 1 MPA 1 0 NRC PDR 02 1 1 OELD 0 OP LIC BR 1 1 POWER SYS BR 19 1 1 PROC/TST REV 20 ' QA BR 21 1 1 1 S BR22 1 REAC SYS BR 23 1 IL 01 1 SIT ANAL BR 24 1 1 STRUCT G BR25 1 1 SYS INTERAC BR 1 1 EXTERNAL: ACRS 27 16 16 L.PDR 03 1 1 NSIC 05. 1 1 thAa ~ 5 Ij)3).

TOTAL NUMBER OF COPIES REQUIREDe LTTR 57 ENCL 51

1 sf'IIASARA 0 MQog@%K NIAGARA MOHAWK POWER CORPORATION/300 ERIE BOULEVARD WEST, SYRACUSE, N.Y, 13202/TELEPHONE (315) 474-1511 March 18, 1981 Mr. B.J. Youngblood, Chief Licensing Branch No. 1 Division of Licensing 5 Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission rn Washington, D.C. 20555 6 r 0

Dear Mr. Youngblood:

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I Re: Nine Nile Point Unit 2 Docket No. 50-410 Enclosed are the handouts provided at the March 6, 1981 meeting with members of the Commission Staff to address unstaggered splices. Your March 5, 1981 letter granted approval for the use of the DYWIDAG Threadbar System in staggered applications at Nine Mile Point Unit 2 provided the following conditions are met:

1) Compliance with the applicable provisions of Section III, Division 2 of ASME Boiler and Pressure Vessel Code, 1980 Edition, including the Summer 1980 addenda;

2) Compliance with the applicable provisions of Section 7.5 and 7.6 of ACI Code 349-76, "Code Requirements for Nuclear Safety Related Concrete Structures".

Additionally, Niagara Mohawk requests approval to utilize the DYWIDAG Threadbar System in unstaggered applications subject to the limitations and conditions described below:

1. Compliance with the above referenced codes.

2. Limited to bar sizes N6-Nll.

3. Limited to doweling at slab to wall junctions as typically shown in Sketch l.

4. The concrete design is in accordance with the strength method and allowable stresses as outlined in ACI-318-76 Code. 5 All seismic Class I reinforced concrete structures are designed I /I utilizing the load combinations for the operating design condition as specified in the Nine Mile Point Unit 2 Preliminary Safety Analysis Report Section 12.3.9. For Nine Mile Point Unit 2, the rebar dowels at wall slab junction of seismic Class I structures are designed for the maximum moment achieved from the worst loading combination for the operating or design condition.

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M'arch 18, 1981 Page Two In case of unstaggered splices at wall slab junction for the Unit 2 Project, the stress level in the dowels will be below 50Ã of the specified yield strength (as required by ACI-349) under all applicable load conditions (i.e., less than 20 ksi). A typical design calculation showing the stress levels at wall slab junctions for two elevations in the Reactor Building is contained in the attached handouts from the March 6, 1981 meeting.

5. The minimum spacing criteria for splices that will be used to avoid the formation of voids during concrete placement is also contained in the attached handouts from the March 6, 1981 meeting.

As requested at the March 6, 1981 meeting, Attachment 1'ompares the elongation and strain of spliced vs unspliced bars at stress levels of 50K of the specified yield strength. As shown by this table the elongation of a splice specimen is essentially identical with the elongation of the unspliced bar at this stress level.

The ACI 349-76 code assures that cracking in concrete due to slip in the splice is adequately controlled by:

l. Demonstrating through qualification testing that the strain in the spliced specimen at 0.9 of the specified yield strength does not exceed that of an unspliced specimen by more than 50Ã.

2. Limiting the maximum computed design load stress in the bar to less than 0.5 of the specified yield strength.

Therefore, Niagara Mohawk does not believe that group testing of unstaggered splices in concrete is necessary based on the commitment to comply with Sections 7.5 and 7.6 of ACI 349-76.

Based on the above, the approval for the limited use of the DYWIDAG Threadbar System in unstaggered splices as specified above, is requested by March 31, 1981.

Very truly yours, yg~ P Donald P. Disc Vice President Engineering

C Niagara Mohawk Power Corporation Nine Mile Point Unit 2 Docket No. 50-410 Presentation DYWIDAG Threadbar Introduction Code Requirements Unstaggered Splices Statistical Summary Calculations

'I Spacing Criteria

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Use of DYNIDAG splices will comply with the requirements of ASME II Code, Division II and ACI 349.

Test results have shown that DYWIDAG splice meets the requirements for unstaggered splices:

1, Strain over length of the full connector at 90K yield is less than 150K of an unspliced bar.

2. Maximum computed design load stress in spliced bar is less than .5 fy.

3. Splices develop at least 125K of the specified yield strength of bar in tension.

4 DYWIDAG Threadbar, grade 60 ksi, Splice System Statistical Summary of Elongation. in a Spliced Bar Specimen versus Elongation of an Unspliced. Bar Specimen at.90% of minimum required yield (54 ksi) 86: Elongation in 10 inch Average Spliced Specimen 0.0245 0.0270 0.0230 0.0265 0.0250 0.0210 0.0245 Unspliced Specimen 0.0195 E in% 26 38 18 36 28 26

87. Elongation in 12 inch . Average Spliced Specimen . 0.028 0.025 0.0285 0.028 0.027 0.022 0.0264 Unspliced Specimen 0.026 EinX 8. -4 10 4 ~ '15

/18: Elongation in 14 inch Average Spliced Specimen 0.037 0.0335 , 0.0365 . 0.033 0.032 0.031 0.0338 Unspliced Specimen 0.028 E in% 32 20 30 18 14 21 Elongation in 15 inch Average Spliced Specimen 0.038 0.0355 0.037 0.035 0.0365 0.039 0.0368 Unspliced Specimen 0.030 E in O/ 27 18 23 17 22 30 23 f/10 Elongation on 18 inch Average Spliced Specimen 0.0485 0.047 0.0465 0.0495 0.0465 0.045 0.0471 Unspliced .Specimen 0.035 E in  %/ 39 34 33 41. 33 29 35 811 Elongation in 18 inch Average Spliced Specimen 0.0455 0.0475 0.039 0.0415 0.046 0.0395 0.0431 Unspliced Specimen 0.034 EinX 34 40 15 22 35 16 27 II 14 Elongation in 22 inch Average Spliced Specimen 0.045 0.050 0.051 0.0505 0.0495 0.050 0.0493 Unspliced Specimen 0.042 Ein% 7 19 21 20 18 19. 17 C

Elongation in 30 inch Average

'6 II 18 Spliced Specimen 0.0845 0.079 0.081 0.076 0.0845 0.082 0.0812 Unspliced Specimen 0.056 Ein% 51 41 45 51 46 45

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MINIMUM SPACING CRITERIA FOR SPLICES TO AVOID FORMATION OF VOIDS DURING CONCRETE PLACEMENT:

1. THE CLEAR DISTANCE BETWEEN PARALLEL SPLICES IN A LAYER SHALL BE NOT LESS THAN THE NOMINAL DIAMETER OF THE BARS, NOR 1 IN.

2. IN CASE OF COMPRESSION MEMBERS, THE CLEAR DISTANCE BETWEEN LONGITUDINAL SPLICES SHALL NOT BE LESS THAN ONE AND ONE HALF TIMES THE NOMINAL BAR DIAMETER, NOR 1 1/2 IN.

THE ABOVE CRITERIA IS IN COMPLIANCE WITH ACI-349-76.

FOR NINE MILE POINT UNIT 2, THE MINIMUM CLEAR DISTANCE BETWEEN PARALLEL SPLICES WILL NOT BE LESS THAN SIX TIMES THE NOMINAL DIAMETER OF THE BAR NOR 6 IN.

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ATTACHNENT 1 OYWIDAG Threadbar, Grade 60 ksi, Splice System Statistical Summary of Elongation in a Spliced Bar Specimen versus Elongation of an Unspliced Bar Specimen at 50 percent of minimum required yield (30 ksi)

No. 6 Elongation in 10 inch Average Spliced Specimen 0.010 0.011 0.008 0.010 0.010 0.008 0.0095 Unspliced Specimen 0.011 Difference in 10 in, 0.001 0.0 -0.003 -0.001 -0.001 -0.003 -0.0015 Difference in Strain 0.0001 0.0 -0.0003 -0.0001 -0.0001 -0.0003 -0.00015 (in./in.)

No. 7 Elongation in 12 inch Spliced Specimen 0.012 0.012 0.013 0.013 0.013 0.011 0.0123 Unspliced Specimen 0.015 Difference in 12 in. -0.003 -0.003 -0.002 -0.002 -0.002 -0.004 -0.0027 Difference in Strain -0.00025 -0.00025 -0.00017 -0.00017 -0.00017 -0.00033 -0.00023 (in. /in.)

No. 8 Elongation in 14 inch Spliced Specimen 0.013 0.012 0.013 0.012 0.012 0.012 0.0123 Unspliced Specimen 0.017 Difference in 14 in. -0.004 -0.005 -0.004 -0.005 -0.005 -0.005 0.0047 Difference in Strain -0.00029 -0.00036 -0.00029 -0.00036 -0.00036 -0.00036 -0.00034 (in./in.)

No. 9 Elongation in 15 in.

Spliced Specimen 0.017 0.017 0.017 0.017 0.015 0.017 0.0167 Unspliced Specimen 0. 017 Difference in 15 in. 0.0 0.0 0.0 0.0 -0.002 0.0 -0.0003 Difference in Strain 0.0 0.0 0.0 0.0 -0.00013 -0.00002

( in. /in. )

No. 10 Elongation in 18 inch Spliced Specimen 0.021 0.021 0.019 .-

0.022 0.020 0.020 0.0205 Unspliced Specimen 0.019 Difference in 18 in. +0.002 +0.002 0.0 +0.003 +0.001 +0.001 +0.0015 Difference in Strain +0.0001 +0.00011 0.0 +0.00017 +0.00006 +0.00006 +0.00008 (in./in)

No. 11 Elongation in 18 inch Spliced Specimen 0.019 0.022 0.018 0.018 0.020 0.017 0.019 Unspliced Specimen 0.019 Difference in 18 in. 0,0 +0.003 -0.001 -0.001 +0.001 -0.002 0.0 Difference in Strain 0.0 +0.00017 -0.00006 -0.00006 +0.00006 0.00011 0.0 (in./in.)

No. 14 Elongation in 22 inch Spliced Specimen 0.020 0.021 0.021 0.023 0.021 0.022 0.0213 Unspliced Specimen 0.023 Difference in 22 in, -0.003 -0.002 -0.002 0.0 -0.002 -0.001 -0.0017 Difference in Strain -0.00014 -0.00009 -0.00009 0.0 -0.00009 -0.00005 -0.00008 (in./in.)

No. 18 Elongation in 30 inch Spliced Specimen 0.033 '0.032 0.031 0.029 0.033 0.031 0.0315 Unspl iced Specimen 0.031 Difference in 30 in. +0.002 +0.001 0.0 -0.002 +0.002 0..0 +0.0005 Difference in Strain +0.00007 +0.00003 0.0 -0.00007 +0.00007 0 o +0. 00002 (in./in.)

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