ML19209A627
| ML19209A627 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/31/1979 |
| From: | Counsil W NORTHEAST UTILITIES |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NUDOCS 7910050084 | |
| Download: ML19209A627 (10) | |
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- ;.s, August 31, 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)
B. H. Grier letter to W. G. Counsil dated July 2, 1979 transmitting I&E Bulletin No. 79-14.
(2)
B. H. Grier letter to W. G. Counsil dated July 18, 1979 transmitting I&E Bulletin No. 79-14, Revision 1.
(3)
B. H. Grier letter to W. G. Counsil dcted August 15, 1979 transmitting I&E Bulletin No. 79-14, Supplement.
(4)
W. G. Counsil letter to B. H. Grier dated August 1,1979.
Gentlemen:
Millstone Nuclear Power Station, Unit No.1 Seismic Analysis for As-Built Safety-Related Piping Systems I&E Bulletin No. 79-14, Reference (1) as amended by References (2) and (3), re-quested Northeast Nucleer Energy Company (NNECO) initiate a program to verify the accuracy of input information for the seismic analysis of safety-related piping.
NNECO's 30-day response required by Reference (1) was submitted August 1,1979, Reference (4).
Reference (1) also required inspections of one system in each set of redundant systems, and all non-redundant systems for conformance to the seismic analysis input information set forth in design documents. This report, (1) addresses progress to date in normally accessible areas- (2) provides the results of these inspections; and (3) provides NNECO's schedule for completing the remaining work required by I&E Bulletin No. 79-14.
Included in the inspection program are:
Pipe run geometry o
Support and restraint design (location, function, clearances) e Floor and wall penetrations e
Embedments (excluding those covered by I&E Bulletin No. 79-02) e 1109 244 7 910 050 C) Ef ib
. e Pipe attachments Valve and valve operator location and weights (excluding those covered e
by I6E Bulletin No. 79-04)
The following systems are presently under examination and verification for the as-built condition. These systems or portions of these systems are generally accessible under normal operation.
Reactor building closed cooling water e
Reactor shutdown cooling e
Fuel pool cooling e
e Service water e Standby gas treatment Condensate storage and transfer e
e Isolation condenser Core spray / low pressure safety injection / containment cooling e
e Atmospheric control e Secondary cooling e Liquid radwaste e Condensate storage and transfer e Station air systems The following systems were classified as inaccessible during normal operation and documentation has been assembled so that verification can proceed during a future shutdown.
e Main steam o Feedwater e Reactor head cooling a Control rod drive piping e Reactor recirculation e Cleanup 1109 245
. Due to extensive inservice inspections (approaching ten years) and the backfit and betterment projects that have been completed or are in progress, the drywell piping has been heavily scrutinized and deviations, if any, are expected to be minor or non-existent.
The main steam piping and safety relief valve discharge piping have undergone modificatiens and reanalysis for operational improvements with the safety relief valves as recently as Spring, 1979. These lines are not expected to be significantly deficient relative to as-built documentation.
The reactor recirculation piping was backfitted with high energy pipe whip restraints and again, geometry is er4rcted to be as designed. Additionally, projects are presently underway for piping modifications to the core spray and clean-up piping in the drywell anc these portions have been reviewed as recently as Spring, 1979.
Other work that has increased our level of confidence consists of hanger modifi-cations (1978) on the core spray, LPSI, and isolation condenser systems that were required due to operational occurrences (water hammer, etc.).
Also, work is now in progress to evaluate safe shutdown system seismic analyses as part of the Systematic Evaluation Program.
Examinations have also been conducted on all seismic systems for the 79-02 Bulletin to verify the design hanger base plates (replscement of missing hangers and modification of base plates was also included in these surveys).
Approximately 40% of the total project scope for I&E Bulletin No. 79-14 (accessible and inaccessible) has been verified to date. This represents 65% of all accessible piping and inspection items. A total of 4,500 linear feet of seismic Category I piping, and 350 associated supports, have been verified. The total quantity of piping surveyed is as follows:
Reactor Building Closed Cooling Water e
Linear feet of pipe surveyed 1,200 Hangers and restraints verified 91 e Standby Liquid Control (Accessible Portion Completed)
Linear feet of pipe surveyed 175 Hangers and restraints verified 30 e Service Pater Sys un Linear feet of pipe surveyed 950 Hangers and restraints verified 36 e Isolation Condenser (Accessible Portion Complete)
Linear feet of pipe surveyed 500 Hanger and restraints verified 41 1109 246
. e Standby Gas Treatment (Accessible Portion Complete)
Linear feet of pipe surveyed 285 Hangers and restraints verified 30 e Fuel Pool Cooling Linear feet of pipe surveyed 246 Hangers and restraints verified 21 e Condensate (Accessible Portions Complete)
Linear feet of pipe surveyed 525 Hangers and restraints verified 44 Atmospheric control and secondary cooling are presently being verified. Liquid radwaste, condensate storage and transfer, as well as station air systems have relatively small seismic portions and are expected to be completed shortly.
It should be noted that even though a system may not be completely " walked down" the packages for analytical review are prepared on the basis of seismic problems and are submitted when the problem has been reviewed in the field. The reverse may also be true if a problem cannot be completed because it is in inaccessible areas, it will not be reviewed unless a major deviation is found.
During system inspections, some docament discrepancies have been identified.
The attached tables delineate the items that have been found. Table 1 presents a summary of the deviations having safety significance found to date. Tables 2 through 5 present the details of all discrepancies.
The most frequent discrepancy to date has been additional hangers that do not appear on design documents.
Even though many of these discrepancies will require a seismic reanalysis, preliminary engineering evaluations indicate that the; will not have a detrimental effect on the seismic integrity of the system.
It is felt that the discrepancies found to date on the piping which has been verified have not been serious enough to affect the integrity of the system involved. Upon completion of all accessible portions, a complete report of the findings and a schedule for completion of any analysis or backfit work will be submitted to the NRC.
It is anticipated that all accessible portions will be completely examined by the end of September, and the complete report of all accessible areas will be submitted at that time.
Based on, (1) the work completed to date, (2) the significance of the discrepancies found thus far, and (3) the plans to complete the findings for all accessible areas by the end of September,1979, NNECO presently concludes that a reactor shutdown and inspection of inaccessible areas may be postponed until the 1980 refueling outage. This conclusion will be re-evaluated by NNECO and submitted h
kf
. to the NRC with the complete report of all accessible areas, by the end of September, 1979. Of course, any shutdowns which may occur due to maintenance problems will be used to initiate as much work as possible inside the drywell.
Since the discrepancies found to date have not been significant and levels of confidence for inspections in the drywell are high, as outlined previously, this is the most expeditious and advantageous approach available.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY W. G. Counsil Vice President Attachments 1109 248
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TABLE S MILLSTONE UNIT NO. 1 PIPING LINES
SUMMARY
(8/27/79)
DIFFERENT GEOMETRY AS SHOWN ON DIFFERENT VALVE SYSTEM LINE NUMBER STRESS ISO LOCATION Condensate 28C-22 1
0 Service Water 8 SW-28b 3
0 8 SW-16b 24 SW-17 Reactor Building Closed Cooling Water 0
0 Reactor Shutdown
~
Cooling 10 SHC-4D 1
1 Standby Liquid Control 3 SLC-15 7
9 2 SLC-BA, BB 24 SLC-1 l% SLC-7A, 7B, 12 Standby Cas Treatment No Line Available 1
O Reactor Isolation Condenser 16 IC-1, 2
3 1
24" Pipe Fuel Pool Cooling 0
0 0
Core Spray /LPCI/
a Containment Cooling <
0 0
0 N
U' LN