IR 05000336/1985001
| ML20128E122 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/14/1985 |
| From: | Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Opeka J NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| NUDOCS 8505290303 | |
| Download: ML20128E122 (2) | |
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MAY 141985 Docket No. - 50-336 Northeast Nuclear Energy Company ATTN: Mr. J. F. Opeka Senior Vice President - Nuclear i
Engineering and Operations Group P. O. Box 270 Hartford, Connecticut 06141-0270 Gentlemen:
Subject: Inspection Report No. 50-336/85-01 This refers to your letter dated April 4,1985, in response to our letter dated March 8, 1985.
Thank you for the requested additional information documented in your letter.
This information is being evaluated by the staff and you will be notified if
.further actions are necessary.
Your cooperation with us is appreciated.
Sincerely, 8e
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Stewart D. Ebneter, Chief Division of Reactor Safety cc w/ enc 1:
E. J. Mroczka, Vice President, Nuclear Operations W. D. Romberg, Station Superintendent D. O. Nordquist, Manager of Quality Assurance R. T. Laudenat, Manager, Generation Facilities Licensing Gerald Garfield, Esquire.
.Public Document Room (POR)
Local Public Document Room (LPDR)
Nuclear Safety Information Center (NSIC)
NRC Resident Inspector State of Connecticut 8505290303 850514
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PDR ADOCK 05000336 G
PDR OFFICIAL RECORD COPY RL MILLSTONE 85-01 - 0001.0.0 05/09/85 non
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. Northeast Nuclear Energy ' Company '
bec w/ enc 1:
Region I Docket Room (with concurrences)
Senior Operations Officer (w/o enc 1)
DRP Section Chief
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S-ld, r OFFICIAL RECORD COPY RL MILLSTONE 85-01 - 0002.0.0 05/09/85
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l N UTIMTIES General Offices * Selden Street. Berlin Connecticut
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P.O. BOX 270
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HARTFORD. CONNECTICUT 06141-0270 (203) 666-6911 as v e cow-L g
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l April 4,1985 Docket No. 50-336 A04718 B11510 Dr. Thomas E. Murley Regional Administrator U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406
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References:
(1)
S. D. Ebneter letter to W. G. Counsil, dated March 8,1985.
(2)
W. G. Counsil letter to T. E. Murley, dated February 22, 1985.
Gentlemen:
Millstone Nuclear Power Station, Unit No. 2 IE Inspection Report No. 50-336/85-01 Unresolved Item 336/85-01-01 Reference (1) transmitted Inspection Report No. 50-336/85-01 for Millstone Unit No. 2 which identified one unresolved item.
Unresolved Item 336/35-01-01 requested additional information concerning Item 4 of Bulletin 79-02 (verification of design requirement for concrete anchor bolts) as follows:
1.
The total' number of inaccessible supports.
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The systems on which each of these supports is installed.
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The total number of inaccessible concrete anchor bolts on each system containing inaccessible supports.
4.
Adequate statistical evidence regarding anchor bolt test results that will assure the functionality of each system - the number of anchor bolts tested / requiring replacement in each system with inaccessible supports.
5.
A description of how each inaccessible support was addressed under the IEB 79-14 requirements.
In Reference (2) Northeast Nuclear Energy Company (NNECO) committed to provide the requested information on or about April 1,1985.
Accordingly, NNECO provides the following information:
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-2-Response Number 1 Table I provides the total number of supports per system along with the total number of inaccessible supports under the scope of Bulletin 79-02.
Supports or anchor bolts are considered inaccessible if access is obstructed due to physical interferences or high radiation levels in all modes of plant operation.
Response Number 2 Table I provides the information on a system by system basis.
Response Number 3 i
Table I provides the total number of inaccessible anchor bolts per system.
Response Number 4 p/...
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Bulletin _L9-02 inspection data _have_been_ collated /and summarized for Millstone Unit No. 2 on Table I. Included in the summary is a system by system total of:
o Quantity of Supports o Quantity of Supports with Anchor Bolts o Quantity of Inaccessible Supports with Anchor Bolts o Quantity of Anchor Bolts Installed o Quantity of Anchor Bolts Inspected o Quantity of Anchor Bolts Inaccessible o Quantity of Anchor Bolt Failures o Reliability with a 95% Confidence Factor The last column delineates the calculated reliability of the Hilti bolts based on a 95 % confidence level.
These values are the results calculated using a hypergeometric distribution to determine with a 95% confidence level that 95%
of the Hilti bolts would be reliable, i.e. fune'ional, in each system.
l In view of the fact that these statistics ate based on testing of all accessible l
anchor bolts and that all failed bolts have been replaced, it is clear that the anchor bolts do meet their design basis and that each system continues to
- maintain a-high degree of reliability. Additionally, Table I provides evidence that the population of inaccessible concrete anchor bolts is sufficiently small.
l When combined with the confidence level derived from the testing of accessible l
bolts and the conservative analysis assumptions described under Response Number 5 for inaccessible anchor bolts, NNECO concludes that these systems
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will remain functional l
l Response Number 5 L
Inaccessible supports were visually inspected at a reasonable distance so as not I
to subject the inspector to unnecessary risk or injury.
Experienced support design personnel visually examined each support for compliance with the current i
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-3-drawing of record. This review included member sizes and lengths, base plate dimensions and attachment locations, Hilti bolt quantities and diar..eters, welded or bolted connections, gaps and proper location and direction of restraint. Any
' abnormalities or discrepancies were so noted for support evaluation.
Support calculations were then performed employing conservative assumptions such as minimum 'embedment on all Hilti bolts, etc. (when in fact _ actual embedment is usually much greater than minimum embedment) to evaluate each support for its rated load.
In summary, NNECO maintained that an adequate anchor bolt testing program has been instituted at Millstone Unit No. 2 and that there is a high degree of confidence that the concrete anchor bolts meet their design basis. Furthermore, the above information demonstrates that all 79-02 requirements were satisfied
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and that the operability of each Category I system is assured.
We trust you will find this information satisfactory.
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Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY
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W. G. Counsil Senior Vice President
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TABLE - !
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MILLSTONE UNIT No. 2 BULLETIN 79-02 INSPECTION DATA SUMMARY OTY OF GTY OF GTY OF RELIABILITY OTY OF INACCESSIBLE 2TY OF
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BTY OF SUPPORTS SUPPORTS ANC. BOLTS ANC. BOLTS ANC.BOLIS ANC.80LT WITH A 951 SYSTEM SUFFORIS N/ANC. BOLTS W/ANC. POLIS INSTALLED INSFECTED INACCESSIBLE FAILURES CONF. FACT.
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MAIN STEAM 295 162
998 898 100
97.29 AUI. FEEthATER 240 139
92,7 892
28 96.55 REACTCRC00LANI 182 152
929 796 133
93.97
' SAFETY' INJECT.
697 442
2519 2437
67 97.10
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CVCS/CH6. PUMP 257 198
719 529 190
96.10
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RBCCW 931 554
3122 2994 128
97.82 SERVICE WATER
'350 301 '
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1425 1247 178
97.54
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SPENT FUEL POOL CCCLING 136
0 457 454
4 98.47 OlESEL 6EN.
39'
3 222 182
1 98.20
CNTMI. VENT
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100.0 CHILLED WTR.
95
457 439
20 94.75 l
e MISCELL'
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67
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100.0
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!!B74 10967 907 287 97.24 TOTAL 3304 2191 138 s includes Cntet Drains. Liquid Radwaste and m 1us Radwaste Penetrations.
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