ML19319C485
| ML19319C485 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/04/1974 |
| From: | Maccary R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Moore V US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8002190933 | |
| Download: ML19319C485 (9) | |
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SEP 4 197 4 V. 4. Moore, Assistant Director for Li~ht 'iater ?.eactors, Group 2 Directorate of 7.icensin~.
DAVIS 303S2 SUCL?AR POUZ?, STATION UNIT 0:i:
Plant tae: Davis 2 ease Nucicar P e r Station Licensing Stago: OL Dacket '.;o.. 50-246 2esponsible *,ranc'a and Project Manager:
LU". 2-3, I. Paltier
'tequested Caepletica Date: 9/6/74 Applicant'a Respons.* Dste Vecessary for Couplation of " ext \\ction
?L2nned on Project:
N.A.
Description of Tesponse: Response to Positions / Request for Additional Information
eviev htus: A;;niting Response A retic's of the infor-ntion furnished by the apnlicant in the FIG anri amenhenta throush 122 has been conolete.1 hv the ".echanical F.agineering Branch. Positions and areas in which additional infor.xstion is required are identifisi in the enclosure.
Orid:mi sided by n n.Lcetry R.
?.. Itsecary, usiatant Director for ".n;i.iecrin;;
91rcetorate of Licensing
Enclosure:
Positions /'tequest for Additional Infor-ation O
O' ce w/enel:
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S. U. Hanswer, DRTA OQ F. Schroeder, L
)d A. Schwencer, L D
J. ?. I' night, L J
v I. A. ?citier, L L J. 3asnak, L Docket Files 50-346 L, Reading File cc w/o enc 1:
L:MEB File A. Ciambusso, L W. C. '4cDonald. L h
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o n o-Fore AEC-3tS (Rev. 9 5 3) AECM 0240 see cas se e s ses.e s ae.a e4 8002190fM
MECHANICAL ENGINEERING BRANCH DIRECTORATE OF LICENSING DAVIS BESSE NUCLEAR POWER STATICN UNIT ONE i
DOCKET NO. 50-346 POSITIONS / REQUEST FOR ADDITIONAL INFORMATION 3.6 Protection Against Postulated Pipe Rupture 1.
Provide the design margin utilized against the formation of a plastic hinge in those piping systems inside containment not directly using the criteria of Regulatory Guide 1.46, and in those piping systems outside containment not directly using the criteria of the A. Giambusso letter of December 15, 1972. These piping systems are discussed in the FSAR in Sections 3.6.2.2.1 and 3.6.2.2.2 and are those which utilize the " span length" method for postulating pipe break restraint locations.
2.
Clarify the response to Question 3.6.3 and Section 3.6.2.5.4 of the FSAR, Our position regarding the consideration of strain rate effects in the design of pipe whip restraints is that an increase in the specified minimum yield strength of not more than 10% may be used in the analysis to account for strain rate effects unless substantiated by applicable experimental results.
3.
Provide additional information in justifi. cation of the dynamic amplification factors and thrust coefficients used in the analysis to demonstrate that they have been conservatively selected.
Section 3.6.2.5.6 indicates that an overall v-lue of 1.67 has been used in
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the general case inside containment. This value is assumed to be a composite product of the thrust coefficient, the gap rebound effects factor and the dynamic Joad factor.
In Attachment A of our letter j
i of 8/28/73 we indicated that the thrust coefficient in the case of saturated steam or water should not be less than 1.26 and that the g
gap rebound factor should be 1.5 unless a lower value was otherwise t
justified by dynamic analysis. With a dynamic load factor of 2.0 I
and the above values for the other factore a composite product value of 3.78 is obtained. Justify the uea of 1.67 inside contain-ment and a value which is apparently 1.5 outside containment (as given in Section 3.6.2.5.9 of the FSAR) in lieu of more conservative multiplying factors.
4.
Section 3.6.2.7.1.5 indicates that only critical cracks were postulated in the coolant letdown system but it also indicates that the criteria of the A. Giambusso letter of December 15, 1972 were met.
Reconcile these statements with the fact that apparently circumferential breaks wer, not postulated.
Similar connents apply to the. reactor coolant makeup system and several of the other systems of Table 3-6a described in detail in Section 3.6.2.7 for which the text apparently indicates only critical cracks but not circumferential breaks have been postulated in systems over 1" nominal pipe size.
5.
Amplify the design details for the guard pipe provided on page j
3-115 of the FSAR by indicating the stress limit applicable to the loading pressure.
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1 Discuss the method of access provided to carry out inservice g
i inspection of the flued head to process pipe welds shown on h
Figures 3-12, 3-13 and 3-15.
Provide the number of openings, I
size, and pressure seating details.
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3.9 Mechanical Systems and Components 1.
The nacerial presented in Section 3.9.1.1 of the FSAR should be expanded to include the following in the piping preoperational vibration and dynamics effects test program:
(a) a list of selected locations for visual inspection and measurements, (b) the acceptance criteria that will be applied to establish that stress and fatigue levels are within design limits, (c) corrective action to be taken should the limits be exceeded.
2.
The response to Question 3.9.2 regarding loading combinations and stress limits is not adequate and should be clarified as follows:
(a) Section 3.9.2.2 (a) of the FSAR is assumed to cover the operating basis earthquake and the other loads acting concurrently including operating transients associated with the upset plant operating
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condition. The stress level produced by the sun of these loads should not exceed the allowable stress permitted by the ASME Code for the appropriate class of component at t e upset plant operating condition.
(b) Section 3.9.2.2(b) of the FSAR is assumed to cover the safe shutdown earthquake and the other loads acting concurrently including those due to faulted condition events such as pipe break.
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r The stress level produced by the sum of these loads should not exceed the allowable stress permitted by the iSME Code for the faulted plant condition for class 1 components.
In the case of class 2 and 3 components the Code does not provide such stress limits except as cove, red in Code Cases 1606, 1607, 1635 and 1636 and these limits should not be exceeded.
3.
The material which was provided on the operability assurance program for active pumps and valves should be expanded to verify that the program which covers ASME Class 1, 2 and 3 active pumps and valves includes the following:
(a) Provision for the testing of appurtenances vital to the operation of setive pumps and valves whenever documented 1
records of applicable previously conducted tests are not available. The testing of such appurtenances should meet i
1 (b) A requirement that the manufacturer of active pumps and valves stipulaten that each pump or valve will operate normally when subjected to the end connection loads associated with the faulted plant condition.
l The material in Section 3.10 and in the response to Question 3.10.1 appears to have already covered some of the information requested in (a) above.
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4.
Provide summary results of component mathematical analyses covering the normal, upset, and faulted plant operating conditions.
Include typical and maximum stress, deflection and fatigue results for representative load sets considered for each operating condition as appropriate. Provide Code or other permitted allow-able values with each reported result. This is applicable to ASMT.
Class 1, 2 and 3 components.
5.
Provide a diagram and the design details of the main steam isolation valves, particularly a discussion of the valves design adequacy to withstand the loading effects of fast closure.
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_y 3.10 Seismic Design of Category I Instrumentation and Electrical Equipment Amplify the response to Question 3.10.1 to demonstrate that:
(a) the single frequency input tests are adequate in that one of the following condicic us was pres.'nt:
(1) The characteristics of.the required input motion indicate that the motion is dominated by one frequency (i.e., by structural filtering effects).
(2) The anticipated response of the equipment is adequately represented by one mode.
(3) The input has sufficient intensity and duration to excite all modes to the required magnitude, such that the testing response spectra will envelope the corresponding response spectra of the individual modes.
(b) testing in which the input is applied to a single axis only is adequate in that it was previously shown rhat equipment response along the vertical direction is not sensitive to vibratory input along the horizontal direction and vice versa.
(c) fixture design used in testing is adequate since the following conditions were present in the test:
(1) Fixture simulated actual service mounting.
(2) Fixture caused no dynamic coupling to the test item.
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5.0 Reactor Coolant System 1.
(a) The response to Question 5.2.8 is partially acceptable. In addition verify that Table 5-13 containing stress limits t
applicable to pumps and vessels will agree with revised l
Table 5-12 now in the FSAR applicable to piping.
(b) See also Questi~on #4 in Section 3.9 which requests that summary results of component mathematical analyses be provided.
This request is also applicable to ASME Class 1 components.
(c) See also Question 12 in Section 3.9 which seeks a clarification on stress limits and loading combinations. This request is also applicable to ASME Class 1 components.
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