ML19254D578
| ML19254D578 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/28/1979 |
| From: | Counsil W, Fee W NORTHEAST UTILITIES |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NUDOCS 7910290103 | |
| Download: ML19254D578 (5) | |
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.,1 September 28, 1979 Docket No. 50-245 Mr. Boyce H. Grier, Director Region 1 Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406
References:
(1)
W. G. Counsil letter to B. H. Grier dated August 1,1979.
(2)
W. G. Counsil letter to B. H. Grier dated August 31, 1979.
Gentlemen:
Millstone Nuclear Power Station, Unit No.1 Seismic Analysis for As-Built Safety-Related Piping Systems I6E Bulletin No. 79-14 requested Northeast Nuclear Energy Company (NNECO) to ini-tiate a program to verify the accuracy of input information for the seismic analy-sis of safety-related piping. NNECO's 30-S y response and 60-day response were submitted in References (1) and (2). This letter is an update of Reference (2);
it addresses progress to-date in normally accessible areas; provides the results of these inspections; and reaffirms NNECO's schedule for completing the remaining work required by I&E Bulletin No. 79-14.
As previously outlined in the 60-day submittal, the inspection program of seismic Category I piping systems is continuing as required by I6E Bulletin No. 79-14.
At present, twenty-one piping systems are included in the investigations and for seventeen of these systems, the accessible portions of piping have bean or will shortly be completely verified. The remaining four systems are classified as inaccessible, during normal operation.
It is projected that walkdowns of all accessible portions of seismic piping systems presently under investigation will be completed, with the finsi report on walkdowns available by October 31, 1979. This represents approxi-mately a 30-day slip in the schedule outlined in Reference (2). This extension is due in large part to two (2) items.
First, the detailed review of the material, parts and equipment list and its comparison to the original seismic stress reports has caused changes in the project scope and additions to the total amounts of pipe anticipated to be verified. The largest effect has been the dif ferences between the seicmic isolation boundary (valve in most cases) and the analytical boundary (anchor).
Secondly, the lack of piping isometrics in plant record files has required large sect ions of piping to be drawn up in the field, thus, reducing the productivity of inspection crews.
1221 310 p3 7910290 1-A total of 9,000 linear feet of seismic Category I piping and 667 associated supports have been verified to date.
This compares with 4,500 linear feet and 350 supports reported in the previous 60-day submittal.
Some inaccessible areas in the turbine building (condenser bay area) have been surveyed during a short maintenance shutdown, whieb occurred in September.
The total quantity of piping surveyed as of September 24, 1979, is as follows:
o Reactor Building Closed Cooling Water Linear feet of pipe surveyed :
1200 (1200)*
Hangers & restraints verified :
91
( 91)
Standby Liquid Control (accessible portions completed) e Linear feet of pipe surveyed 275
( 175)
Hangers & restraints verified 30 ( 30) e Service Water (accessible and inaccessible portions complete)
Linear f eet of pipe surveyed:
Accessible 1120 ( 950)
Inaccessible 140 (
0)
Hanger, & restraints verified : Accessible 80 ( 36)
Inaccessible 4
(
0) e Isolation Condenser (accessible portion completed)
Linear feet of pipe surveyed :
500 ( 500)
Hanger & restraints verified :
48
( 41) e Standby Gas Treatment (accessible portions complete)
Linear feet of pipe surveyed:
550 ( 285)
Hangers & restraints verified:
40 ( 30) e Spent Fuel Pool Cooling Linear feet of pipe surveyed:
246
( 246)
Hangers & restraints surveyed :
75
( 21) e Condensate Linear feet of pipe surveyed:
Accessible 700 ( 525)
Inaccessible 100 (
0)
Hangers & restraints verified: Accessible 52
( 44)
Inaccessible 7
(
0)
- Number in ( ) represents data reported for 60-day submittal.
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. Shutdown Cooling (accessible portions complete) e Linear feet of pipe surveyed: 600 ( 0) Hangers & restraints verified : 55 ( 0) e Core Spray /LPSI/ Containment Cooling Linear feet of pipe surveyed: 700 ( 0) lbngers & restraints verified: 75 ( 0) e Secondary Cooling System Linear feet of pipe surveyed: 991 ( 0) Hangers & restraints verified: 55 ( 0) Feedwater (accessible portions complete) e Linear feet of pipe surveyed : 545 ( 0) Hangers & restraints verified : 42 ( 0) e Control Rod Drive Linear feet of pipe surveyed: 15 ( 0) Hangers & restraints verified: 0 ( 0) e Radwaste (system complete) Linear feet of pipe surveyed: 77 ( 0) Hangern & restraints verified: 9 ( 0) Atmospheric Control (accessible portions complete) e Linear feet of pipe surveyed: 660 ( 0) Hangers & restraints verified: 39 ( 0) Fire / Domestic Condensate Transfer and Storage (accessible portions complete) e Linear feet of pipe surveyed: 418 ( 0) Hangers & restraints verified : 28 ( 0) e Primary Containment Cooling Service Water (accessible portions complete) Linear feet of pipa surveyed : 370 ( 0) Hangers & restraints verified : 18 ( 0) The following systems are considered completely inaccessible at this time. Reactor Head Cooling Nuclear Boiler Reactor Re-irculation Main / Extraction / Auxiliary Steam 1791 / 1 ') t L t. 1 JlL
Presently, a total of sixteen completed walkdown packages have been forwarded to NNECO's architect engineering firm for review and comparison to original stress analyses. The systems rejresented by these packages are as follows: Accessible Inaccessible Portions Partions Completed _ Completed Standby Liquid Control Yes Reactor Building Closed Cooling Water Isolation Condenser Yes Shutdown Cooling Yes Fuel Pool Cooling Condensate Service Water Intake Structure Yes Yes Atmospheric Control Yes Standby Cas Treatment Yes Feedwater Radwaste Yes Yes It should be noted that even though a particular system may have all accessible portions walked down, it may not be possible to completely review the stress analysis because portions of a problem area are inaccessible. It is anticipated that system stress reviews based on walkdown packages will be completed within the bulletin guidelines: 30 days af ter the initial engineering judgment on system operability. Preliminary site engineering reviews and stress analysis reviews accomplished by NNECO's architect engineering firm have not uncovered any deviations which would af fect saf e operation of the plant. Although reanalysis to prove the validity of the engineering judgments are presently underway, the evaluation of each deviation will be conducted and upon final analytical review, the results will be forwarded to the NPC. Based on, (1) the high degree of confidence developed during the inspections that have been completed to-date, and (2) the system work performed inside the drywell, as delineated in the previous 60-day submittal, NNECO reaffirms the conclusion that shutdown and inspection of inaccessible areas may be postponed until the 1980 refueling outage. Preparations are underway to prepare to the maximum extent possible to conduct the remaining surveys in an expeditious and accurate manner. 1221 313
-5 Any unplanned shutdowns which may occur due to maintenance problems will be used to complete as much of the inaccessible areas as possible. Since the discrepancies found to--date have not been significant and levels of confidence for inspections in the inaccessible areas remain high, as outlined in Reference (2), this is the most expeditious and advantageous approach available to NNECO. We will make a follow-up submittal to include the results of all accessible areas and the inaccessible areas where possible, at an expected completion date at the end of October, 1979. Very truly yours, NORTIIEAST NUCLEAR ENERGY COMPANY W. G. ddunsil Vice President BY: W. F. Fee Vice President ') ')
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