ML19347A792
| ML19347A792 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 09/26/1980 |
| From: | Sylvia B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| 685, NUDOCS 8009300249 | |
| Download: ML19347A792 (9) | |
Text
._
w VinorwrA Er.ucrnic ann Powna COMPANY Rzenxown,Vamosm ze can61 September 26, 1980 Mr. Thomas Novak, Assistant Director Sarial No. 685 for Operating Reactors N0/RMB Division of Licensing Docket No. 50-338 U. S. Nuclear Regulatory Commission License No. NPF-4 Washington, D. C.
20555
Dear Mr. Novak:
MULTI STRUCTURE ARS CONCERN NORTH ANNA UNIT 1 This is in response to your letter dated July 25, 1980 requesting additional information regarding the Multiple Structure ARS Evaluation of North Anna Unit 1 piping systems design.
Your letter requested that we summarize the results of our Phase I evaluations, describe the evaluations performed. list the systems found acceptabic during the Phase I evaluation, and provide the bases for their acceptability.
In addition, you requested that we provide the results of our Phase II evaluation which was initially scheduled for completion on Unit No. I by September 15, 1980.
Our letter to you of the same date, July 25, 1980, provided a summary of the results of Phase I on North Anna Unit No. I and changed our target date for completion of Phase II to December 31, 1980 since Phase II will be completed concurrently on Units 1 & 2.
It is therefore the intent of this letter to respond to item no. 1 only of your request for additional information.
Items 2 and 3 cf your request will be addressed following completion of the Phase II evaluation.
Our response to item no. 1 is given below:
NRC Request 1.
Summarize the results of your Phase 1 evaluations.
Include a des-cription of the evaluations performed and provide the bases for their acceptability. List the problems and systems found acceptable af ter the Phase I evaluations and bases for their acceptability.
Response
1.
As stated in our letter Serial No. 649, dated July 25, 1980, the Phase I engineering ef fort of the Multiple Structure ARS Evaluation of Unit I has been completed.
Of the 68 stress problems requiring review, 36 were found acceptable, and the remaining 32 were classi-fled as requiring reanalysis in Phase II.
Table 1 identifies the status of each problem and provides the basis for acceptability under the Phase I effort.
l 80 09 3 0 0 2 'f P
t o
Mr. Thomas Novak ho ws4 Et.rctnic Axo Powen Coxrm to The objective of the Phase I engineering evaluation was to determine the offect on piping systems which span more than one s true :ure, when subjected to multiple structure amplified response spectri (ARS).
This evaluation was performed by reviewing the steps of the c:,mputer-ized design basis analysis for effects of revised ARS.
The effect on the overall results can, in many cases, be determined without computerized reanalysis.
As a first step in the evaluation, the acceleration IcVels and response frequencies of the original design ARS were compared to those of the alternate structure's ARS to determine the frequency range, if any, within which the alternate ARS exceeds the design ARS.
The modal analysis of the piping model is then examined to determine whether any significant piping system vibration modes fall within areas (f retuencies) where the alternate ARS is higher.
If no taodes fall within these non-enveloped areas, then the original design basis is unaffected and the problem is acceptable.
Where one or more piping system modes fall within a non-enveloped area, further examination is required to evaluate the overall effects.
For each af fected mode, modal response was reviewed to determine the expected response increase due to increased acceleration. The review includes examination of relative mass participation, identification of the piping region and associated supports most affected, and evaluation of applicable combined results for all the system modes.
Insignficant response increases were shown for many cases where small increases in acceleration or low mass participation for an affected mode applied.
In some cases, significant increases in one or more vibration modes do not appreciably affect the combined results due to the modal SRSS technique employed. Although one mode's response (forces, deflections) may be significantly increased, the effect on the total combined system response may be small. This determination considers the possible effect on support loads as well as piping stress levels.
For problems showing moderate increases in total response, an esti-mate of magnitude of increase was made to compare system stresses and support and equipment loads with their respective maximum calculated loads.
Where this comparison indicated that the loads would be acceptable, they were placed in Category A.
Because of inherent complexities in certain problems and their analy-ses, not all problems lent themselves to a deterministic evaluation using the simplified methods described above.
If the magnitude of expected response increase could not be determined by simplified means, or if it became evident that a more rigorous analysis was appropriate, the problem was classified as Category B.
The Category B problems will receive a more detailed examination, such as computer reanalysis, within the Phase II effort of the evaluation program.
o Vat'oisir ELECTRIC AND POWER COMPANY TO As stated previously, we will provide our response to items 2 and 3 of your request for additional information following completion of the Phase II evalu-ation.
Please let us know if you have any question or comment concerning the information provided above.
Very truly yours,
[
. S Ivia nager - Nuclear Operations and Maintenance RMB/smv:SC3 cc:
Mr. Robert A. Clark, Chief Operating Reactors Branch No. 3 Division of Licensing Washington, D. C.
20555 Mr. B. J. Youngblood, Chief Licensing Branch No. 1 Division of Licensing
^.,
Washington, D. C.
20555 Mr. James P. O'Reilly, Director Office of Inspection & Enforcement Region IT Atlantn, GA 30303
TABLE 1 - N.A. UNIT NO. 1 PHASE I PIPING PROBLEM DESCRIPTION CATEGORY BASIS FOR ACCEPTABILITY MSK-105F SERVICE WATER:
Supply to Recire. Spray Heat Exchanger A
Piping problem has no modes whose frequencies fall within regions where the alternate ARS MSK-105J SERVICE WATER:
exceeds the design basis ARS Flow to the Containment Recire. Spray A
Heat Exchanger MSK-111N SAFETY INJECTION:
i?ot Leg Injection A
SSR-11 CIIARGING:
Piping Upstream of Regenerative A
Heat Exchanger MSK-103C COMPONENT COOLING:
Return from "A" RHR Heat Exchanger A
Affected modes have negligible response increases due to insignificant increases MSK-103D COMPONENT COOLING:
in acceler.ation or low mass participation Return from "A" RCP A
MSK-103K SAFETY INJECTION:
Cold Leg Injection A
MSK-103AP COMPONENT COOLING:
Return from "B" RCP A
MSK-111S SAFETY INJECTION:
Hot Leg Injection A
MSK-118A COMPONENT COOLING:
Supply to RCP "C" A
MSK-118E COMPONENT COOLING:
Return from RCP "A" and "B" A
MSK-1180 COMPONENT COOLING:
Return from Recire. Air Cooling A
~
Pag? 2 TABLE 1 - N.A. UNIT NO. 1 PHASE I PIPING PROBLEM DESCRIPTION CATEGORY BASIS FOR ACCEPTABILITY MSK-103G COMPONENT COOLING:
A Affected modes exhibit significant increases Supply to "B" RCP in individual modal response, but effects on combined analysis results will be negli-MSK-103J COMPONENT COOLING:
gible.
Supply to "A" RHR Heat Exchanger A
MSK-103AE SAFETY INJECTION:
llot Leg Injection A
MSK-103AN COMPONENT COOLING:
Supply to "A" RCP A
MSK-104F RESIDUAL HEAT REMOVAL:
Pump Back Tc RWST After An Outage A
MSK-104G QUENCH SPRAY:
Flow To Spray Header "B" Pump t.
MSK-104H QUENCH SPRAY:
Flow To Spray Header "A" Pump A
MSK-107C QUENCH SPRAY:
Pump Discharge To Containment "B" Pump A
MSK -107D QUENCH SPRAY:
Pump Discharge To Containment "A" Pump A
MSK-111Q SAFETY INJECTION:
Discharge of Boron Injection Tank A
MSK-121-E CONTAINMENT VACUUM:
Line To Air Ejector /Used in Startup A
SSR-7 (SA-7236)
SEAL INJECTION:
Manifold To "A",
"B",
& "C" RCP's A
SSR-14 LETDOWN:
Piping Downstream of Reg. Heat Exchanger A
Pega 3 TABLE 1 - N.A. UNIT NO. I s
PHASE I PIPING PROBLEM DESCRIPTION CATEGORY BASIS FOR ACCEPTABILITY MSK-101C MAIN STEAM:
A Modal response increases have moderate Main Steam From "B" Generator effects on combined results, but increased stresses and support and equipment loads MSK-101D MAIN STEAM:
are expected to be within design capabili-Main Steam from "C" Generator A
ties.
MSK-102A FEEDWATER:
Feedwater To "A" Steam Generator A
MSK-102B FEEDWATER:
Feedwater to "B" Steam Generator A
MSK-103F COMPONENT COOLING:
Paturn From "C" RCP A
MSK-105G SERVICE WATER:
Return From Recire. Spray Heat Exchanger A
MSK-105H SERVICE WATER:
Flow From The Containment Recire. Spray A
Heat Exchanger MSK-114B QUENCH SPRAY:
"B" Pump DischarRe To Spray IIcader A
MSK-114D RECIRC. SPRAY:
"D" Heat Exchanger To Spray Header A
MSK-114G RECIRC. SPRAY:
"B" Outside Pump To "C" Heat Exchanger A
MSK-118H COMPONENT COOLING:
Supply To Recire. Air Cooling A
Pcg2 4 TABLE 1 - N.A. UNIT NO. 1 PHASE I PIPING PROBLEM DESCRIPTION CATEGORY BASIS FOR ACCEPTABILITY MSK-101A MAIN STEAM:
B Acceptability to be determined in the Main Steam To Turbine Phase II effort.
MSK 101B MAIN STEAM:
7 Main Steam From "A" Generator B
MSK-102C FEEDWATER:
Feedwater To "C" Steam Generator MSK-102D FEEDWATER:
Feedwater To Generators B
MSK-103B COMPONENT COOLING:
Supply To "B" RNR Heat Exchanger
'l MSK-103E COMPONENT COOLING:
Return From "B" RHR Heat Exchanger n
MSK-103R SAFETY INJECTION:
Cold Leg Injection
'l MSK-103AC SAFETY INJECTION:
Hot Leg Injection R
MSK-103AM COMPONENT COOLING:
Supply To "C" RCP M
MSK-104A LOW HEAD SAFETY INJECTION:
Pump Discharge To Containment M
MSK-104D RECIRC. SPRAY:
Outside Pump "A" Discharge B
MSK-107B SAFETY INJECTION:
Low Head To High Head Cross Connect B
J e
~_
Page 5 TABLE 1 - N.A. UNIT NO. I s
PHASE I PIPING PROBLEM DESCRIPTION CATEGORY BASIS FOR ACCEPTABILITY MSK-111B SAFETY INJECTION:
B Acceptability to be determined in the Low Head to High Head Cross-Connect Phase II effort "A"
Pump
~
FSK-111C SAFETY INJECTION:
Low Head To High Head Cross-Connect "B" B
Pump RWST Suction MSK-114E QUENCH SPRAY:
"A" Pump Discharge To Spray Header U
MSK-114F RECIRC. SPRAY:
"A" Outside Pump to "D" Heat Exchanger MSK-114K EECIRC. SPRAY:
"B" Cooler To Spray Header U
MSK-114L RECIRC. SPRAY:
"A" Heat Exchanger To Spray Header U
MSK-114M RECIRC. SPRAY:
"C" Heat Exchanger To Spray Header B
MSK-118B COMPONENT COOLING:
Supply To RCP "A" and "B" B
MSK-118C COMPONENT C00L'NG:
Supply Header To Containment B
MSK-118D COMPONENT COOLING:
Return Header To Containment 3
MSK-118F COMPONENT COOLING:
Return From RCP "C" B
MSK-118K COMPONENT COOLING:
Main Supply To Unit 2 Containment M
MSK-118N COMPONENT COOLING:
Main Return From Unit 2 Containment B
e
Paga 6 TABLE 1 - N.A. UNIT NO. 1 PHASE I PIPING PROBLEM DESCRIPTION CATEGORY BASIS FOR ACCEPTABILITY MSK-121A COMPONENT COOLING:
B Acceptability to be determined in the Supply To Fuel Pool Heat Exchanger Phase II effort MSK-121B COMPONENT COOLING:
Return From Fuel Pool Heat Exchanger n
SSR-7 (SA-7223)
SEAL INJECTION:
Injection to RCP "A" B
SSR-7-(SA-7209)
SEAL INJECTION:
Injection To RCP "B" M
SSR-7 (SA-7198)
SEAL INJECTION:
Injection T9 RCP "C" B
SSR-8 (SA-7217)
SEAL RETURN:
Combined Return "A",
"B",
& "C" RCP SSR-8 (SA-7234)
SEAL RETURN:
Combined Return "A",
"B", & "C B
RCP (Outside) 4 k
-