ML20093N517
| ML20093N517 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 07/11/1984 |
| From: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 29822, NUDOCS 8408020015 | |
| Download: ML20093N517 (16) | |
Text
w Consumers Power James W Cook b
Vice President - Projects, Engineering and Construction General offices: 1945 West Parnell Road, Jackson, MI 49201 * (517) 788 0453 July 11, 1984 Mr Harold R Denton, Director Office of Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 MIDLAND ENERGY CENTER MIDLAND DOCKET NOS 50-329, 50-330 NRC REQUEST FOR ADDITIONAL INFORMATION ON VOLUME IX OF THE SEISMIC MARGIN REVIEW REPORT FILE:
B3.7.1 SERIAL: 29822
REFERENCE:
(1) LETTER FROM J W COOK TO H R DENTON DATED FEBRUARY 9, 1984 (2) LETTER FROM E G ADENSAM (NRC) TO J W COOK DATED MAY 25, 1984 ATTACHMENT: RESPONSE TO NRC QUESTIONS ON SEISMIC MARGIN REVIEW VOLUME IX In Reference (1), Consumers Power Company submitted Volurae IX of the Seismic Margin Review Report titled, " Balance of Plant Class 1, 2 and 3 Piping, Pipe Supports and Valves," for the Staff's review. Subsequently, in Reference (2) the NRC requested additional information on Volume IX.
As an attachment to this letter, Consumers Power Company is submitting responses to the questions contained in Reference (2).
It is expected that this information will enable the NRC Staff to complete its review of Volume IX of the Seismic Margin Review Report.
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~JWC/DRW/bjw CC DSHood, Midland Project Manager, US NRC, Washington DC JGKeppler, Administrator, NRC Region III Midland NRC Resident Inspector Office LJAuge, Manager, ETEC 8408020015 840711 PDR ADOCK 05000329 A
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CONSUMERS POWER COMPANY Midland Units 1 and 2 Docket No 50-329, 50-330 Letter Serial 29822 Dated July 11, 1984 At the request of the Commission and pursuant to the Atomic Energy Act of 1954, and the Energy Reorganization Act of 1974, as amended and the Commission's Rules and Regulations thereunder, Consumers Power Company submits additional information on the Seismic Margin Review Report Volume IX titled,
" Balance of Plant Class 1, 2 and 3 Piping, Pipe Supports., and Valves."
CONSUMERS POWER COMPAhT By amTs W Cook, Vice President
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Pro cts, Engineering and Construction Sworn and subscribed before me this g day of Ouf /9J V.
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Notary Public Jackson County, Michigan My Commission Expires _.
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SMA 13701.05M476 g
RESPONSE TO NRC QUESTIONS ON SEISMIC MARGIN REVIEW MIDLAND ENERGY CENTER PROJECT VOLUME IX d
BALANCE OF PLANT CLASS 1, 2, AND 3 PIPING i
PIPE SUPP0F.TS AND VALVES i
Question 1 Explain the derivation of EQ (5-1).
(pg. IX-5-3) a Y
Response (1)
-g
-A The vector sum of the three orthogonal components of acceleration y
including deadweight must be equal or less than 3.0g.
If the seismic q
portion of the three acceleration components are increased by a factor
]
FSME to a point that the resulting vector is 3.0g, the equation can be di written as:
'I (F
A y 2'h A )1 f
2 2
A, + 1)l j F
+
F
= 3.0
+
\\
x]
\\
}
\\
)-
1 A is the vertical seismic acceleration in g's, AX and Az are the two y
orthogonal horizontal seismic acceleration components in g's and 1 is the deadweight component in g's.
If both sides are squared and the equation rearranged, Equation 5-1 results.
2 2
4 5=
4 m
l d
1
=
d N
i Question 2.
Explain " Drawings of each pipe support were also reviewed in (Pg.IX-6-1) order to assess appropriateness of stiffness assumptions used in modeling." Was generic stiffness, estimated and/or calculated stiffness or NUPIPE default stiffness used?
Response (2)
The architect / engineer piping models used for design were used as infor-mation sources for geometry, valve weights, thermal anchor displacements, thermal loading cases, etc. For design, snubbers and other seismic re-straints were assumed to be rigid.
In the SME study, the design models were reconstructed for use in the NUPIPE computer code. During construc-tion of the NUPIPE models, piping isometrics and support drawings were
(
reviewed to verify the original design input.
In almost all cases, the assumption of rigid supports was judged to be reasonable.
In one model of the service water header, actual support stiffnesses for the 36-inch diameter header were calculated.- None of the models had fundamental frequencies above 10 Hz, consequently, fine tuning of support stiffness was not considered necessary.
Generic stiffnesses were input into NUPIPE to model the supports as essentially rigid except in the one case cited above.
2
c 1.-
Question 3.
Explain why two " Class 1 and 3/4" Class 1 lines were analyzed (Pg IX-6-5) in accordance with Class 2 rules because of the small line size."
Response.(3)
Two l'? and.3/4" Class 1 lines were analyzed in accordance with Class 2 rules because ASME subsection NB3630(d)(1) states that piping of 1" nominal pipe size or less which has been classified as Class 1 in the Design Specifications
- may be designed in accordance with the design requirements of subsection NC (Class 2).
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1
. Question 4 Explain your use of 3% (SSE) damping for the 12" nominal line.
(Pgs IX-6-6, This is not in agreement with Regulatory Guide 1.61 October IX-6-32) '1976.
The Regulatory Guide states that 2% (SSE) damping should be used for lines equal to or less than 12."
~
Response (4)
The damping used is consistent with the criteria and methodology initially proposed to the staff, Reference 1, and included in the Volume I, " Methodology and Criteria" report. Higher than Regulatory Guide 1.61 damping was proposed on the basis that experimental data supported increased damping for piping.
After an extensive review of the existing damping data, the pressure vessel research committee (PVRC) has recently recommended damping substantially in excess of the Regulatory Guide 1.61 damping (and the 3% used in the Seismic Margin Review Report) with no differentiation in pipe size, see Figure 4-1 for comparison of Regulatory Guide and PVRC damping. The recent PVRC recommenda-tion.does result in lower than Regulatory Guide 1,61 damping for large dia-meter pipes (greater than 12 inches) at frequencies above about 17 Hz.
' Fundamental frequencies for the two systems in question are 10 Hz and below.
-In the first model cited, there are six modes below 17 Hz and in the second model there are 8 modes below 17 Hz.
Above 17 Hz there is not a very signifi-cant difference in.the SME spectra between 2% and 3% damping.
o Reference 1.
Kennedy, R P and Stevenson, J D. Seismic Margin Review Criteria, Structural Mechanics Associates Report, SMA 13701.01, July, 1981.
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PVRC
-- - - - RG 1.41 5
i 4
)
SSE (D > 12")
33 SSE (D $ 12")
OBE ID > 12")
1 - - - - - - - - - - - - - - - - - - - - - -
08E 10 $ 12")
0 l
l I
I I
I O
5 10 15 20 25 30 Frequency (Hz)
FIGURE 4-1. PVRC proposed damping vs RG 1.61 damping.
t h
.r,_,___,,_.____s_-,w..--,____
,,,,,,.-..c,-._-,_
_,y.~,,_-4
.,....,y---. _. _.......
Question 5.
With respect to thermal anchor displacements, does the Z Pg IX-6-22 displacement include the radial expansion of the 36" diameter uf the 36" - 2 CCA-1 line?
Response (5)
Thermal displacements of the NSSS were provided by Babcock and Wilcox.
The maximum Z displacement specified was 0.007 inches at the pipe center-line. The branch piping model begins at the outside diameter of 36"-2CCA-1 and should have included piping radial displacement. The radial expansion is about 0.07 inches at 6000F. The branch line penetrates the 36" line at an angle of about 200 from the vertical (Y) axis. Thus, additional displacements of about 0.024 inches in the Z direction and 0.066 inches in the Y direction should have been included. The effect of neglecting these displacements is anticipated to be small since there is over 44 feet from the piping branch point to the first Z restraint at node 93 and over 40 feet to the first Y restraint at Node 98. The support margins at nodes 93 and 98 are 2.75 and 1.40 respectively relative to code allowables, (see Table IX-7-1). The seismic factors are substantially larger. The increased support reactors from additional radial thermal displacement are not considered to be signficant for such a flexible span of pipe and support margins ar judged to be affected very little.
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Question 6.
Explain why the assumption that the seismic displacement Pgs. IX-G-32 of the reactor building supports being out-of-phase with the IX-6-70 auxiliary building supports will always result in higher IX-6-83 support loads.
Response (6)
Building displacements are calculated using the response spectrum tech-nique. Resulting displacements are unsigned and could occur in either a positive or a negative direction at any point in time.
If a piping system is anchored to the reactor bulding at a penetration and is supported in the auxiliary building in the X, Y and Z directions, the largest displace-ment of the reactor building anchor point relative to the auxiliary building support point is to assume that the two building responses are exactly out-of-phase. That is, the peak displacements occur in diametri-cally opposing directions simultaneously. The relative displacement used as input is, therefore, the sum of the absolute values of the two building displacements. This results in an upper bound on required flexure of the piping and an upper bound on the support loading.
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Question 7.
Your statement "With the 3% damped spectra being Pg. IX-6-55 selected since virtually the entire system consists of large piping equal to or greater than 12-inch nominal diameter" does not agree with Reg. Guide 1.61 October 1976. Large piping is defined as greater than 12" and small piping is defined as equal to or
'less than 12".
Thus the 2% dampti spectra should be used for the 12" line 12"-1HCB-6. Justify or correct the value used.
Response (7)
See response to Question (4)
J t
, - _, ~.. _ _
_. _, _ _. ~. _ _
4 Question 8.
Explain why there is no Z earthquake anchor disp 1'acement Pg IX-6-83 for anchor nodes 800 and 875.
Response (8)
Z displacements were used in the analysis. Table IX-6-21 was cut off.
The missing information is provided in Table 8-1.
TABLE 8-1 ADDITIONAL ANCHOR DISPLACEMENTS FOR LOAD SET 3, MAKEUP #ND PURIFICATION SYSTEMS, UNIT 2 Translational X
Y Z
Set No Node In In In 3
800 0.00000 0.00000
.h0100 3
120 0.00000 0.00000
.08100 3
550 0.00000 0.00000
.06750 3
863 0.00000 0.00000
.08h60 3
875 0.00000 0.00000
.!^100 3
857 0.00000 0.00000
.07200 9
.... _.. _. _ _. _ -,. _ - _ - _ _ _. _. ~, _. _
Question 9.
Explain why all the thermal anchor displacements for Pg. IX-6-104 the four different operating cases are the same.
Response (9)
Anchor displacements were taken from the architect engineer's piping analysis model and were identical for all four modes. Actual displace-ments would be different for the four thermal modes. The anchor point in
. question is a nozzle on the 36" cold leg of the primary coo,lant loop.
Updated information from Reference 2 shows that maximum thermal anchor displacements occur at 100% power and are:
X 0.683 in.
Y 1.374 in.
Z 0.714 in.
Displacements for less than 100% power are lower. The updated maximum displacement values are less than those provided by the A/E and used in the SME study; thus, the constant values used are conservative and envelope all four' load cases.
Reference 2.
Babcox and Wilcox Specification 18-1235000012-09 for Reactor Coolant System Support and Foundation loadings, Rev. October 1982.
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o a
- Question 10. The snubber at Node 395(1-610-3-22) has a seismic margin Pg. IX-7-13 load of + 2802 lb and CM and FSME = 4.61.
The snubber at Node 406 (1-610-3-45) has a seismic margin load of + 2785 lb and a CM and FSME = 1.55.
Explain why there is a
'large difference in the CM values.
Response (10)
The snubbers are different sizes. The snubber at Node 395 has a rated load of 11,520 lbs vs 2300 lbs for the one at node 406. The margin for the larger capacity snubber (Node 395) is based upon the supporting steel being the weaker link whereas the margin for the smaller snubber (Node 406) is based upon the snubber rated load capacity, increased for faulted conditions.
i i
i I
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Question 11-The snubber at Node 214 (0-618-1-502) implies that it may be (Pg IX-7-24) a Pacific Scientific Snubber Model 10K or equivalent If this 3
is true explain why its stiffness which is 1.74 x 10 in was not included in the computer model for the 36" piping of the service water system along with the calculated beam and strain-er nozzle stiffness.
Response (11)
The snubber is an ITT Grine11 size 3 unit, see ITT Grine11 Catalogue, Fig 307N,. size 3.
It reacts in the Z direction on line 36" OHBC-15 (see Figure IX-6-76A). Without the snubber, the line would be very flexible in the Z direction due to the presence of a bellows joint at node 217; thus, the assumption that the support is rigid is justified based on the relative stiffness of the snubber vs the stiffness of the line.
12 MIO784-0283A-MPO4
o Question 12.- What ASME Section III Edition Stress Indices for Class 1 General Analysis did the NUPIPE computer code use?
Response (12)
The 1974 code with no addenda was used for Class 1 piping. See Volume I, Methodology and Criteria.
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Question 13. The staff assumes the following to be typographical errors.
Please confirm this assumption, or justify your position:
)
i Page Staff Comment IX-4-1 "SSE" should be "SME" (two places).
IX-5-8
" Snubber (z)" should be "Y Restraint."
See page IX-7-25.
IX-6-178 and
" Class 2 Stresses" should be IX-6-198 to 201
" Class 3 Stresses."
Response (13)
They are indeed typographical errors.
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