ML20128B364
| ML20128B364 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 10/07/1969 |
| From: | Richard Lee US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Boyd R US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9212030636 | |
| Download: ML20128B364 (3) | |
Text
___
Cbd g
\\.
*4 UNITED STATES phM
- ATOMIC ENERGY COMMISSION
- l. Q )g.
I WASWNGTON. O C.
20545 k. ',,,.,
October
,7, 1969 R. S. Boyd, Assistant Director for Reactor Projects, DRL
/"? M THRU:
D. R. Muller, Chief, Reactor Project Branch #1, DRL SITE VISIT AND TECHNICAL MEETING WITH NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT UNIT 1, DOCKET NO. 50-263 on September 17, 1969, a site tour was conducted at Monticello Nuclear Generating Plant by Northern States Power Company for the purpose of reviewing the general plant features and instrumentation, control and electrical systems by members of the DRL staff, and reviewing the seismic design implementation by our seismic consultant Dr. William Hall. Members of the DRL staff who attended the site visit were D. Vassallo, D. Muller, and R. Lee of RP, and T. Ippolito of RT.
Following the tour, a meeting was held at the site for the purpose of discussing certain aspects of the seismic design which are of concern to Drs. Newmark and Hall. On the following day a rieeting was held with NSP and its contractors to discuss items which require further review or documentation.
Questions documenting the concerns of Drs. Newmark and Hall have been submitted to LRL and include the following areas:
(1) Dynamic Analysis The length of time of record used for input for the time-a.
history analyses, b.
A clarification of the approach to the design employed for the housing of Class I equipment in Class II structures, A listing of items analyzed by the response spectrum method, c.
and a recheck of the analysis to confirm design conservatism.
d.
Confirmation that all Class I items were analyzed for the DBE as well as the OBE.
Clarification of the method, or a reanalysis of the method e.
enployed in the time-history approach to ensure that the results obtained were satisf actory and representative.
f.
Further discussion of the basis for the source of the ampli-fication facters presented in Table 12-2-69 of the FSAR, and the method used in the analyses.
- g2Sgg g; g2 O
1 4
3 4
R. S. Boyd '
j g.
Confirmation that the piping analysis was carried out for the DBE
^
as well as the OBE. A tabular summary of sample stress results to indicate conservatism in the design. Comparison with code
. allowable stresses specified in the design criteria.
?
h.
Discussion of the methods of computing elastic and plastic j
strains for reactor internals, and the basis by which computed-strains were compared to the design criteria. Indication of-margin of_ safety and inclusion of energy. absorption criteria.
l (2) Further amplification of stress and deformation limits for concrete and steel to permit an evaluation of the margin of safety that may be available.
(3) Clarification that thermal loads were combined with other loads as applicable for equipment and piping.
l (4) Seismic design criteria and method of verifying that seismic design has been implemented for purchased items, e.g., main steam line isola-tion valves and battery racks.
l On September 18, 1969, a meeting was held with Northern States' Power and its contractors to discuss scheduling for. the submittal of further documentation on areas' requiring additional rcview.
In anticipation of a December 1969 ACRS, the applicant-indicated a desire'to have several technical meetings with the staf f in the immediate future to resolve the outstanding issues as quickly as possible. NSP. proposed that documentation of the outstanding material should:be submitted to DRL'by October 15, in order to maintain the proposed schedule.
l The following items were discussed at'the technical meeting:
(1) The applicant stated that they will incorporate in their design additional safety features whi'ch have arisen as a result of the Dresden review. These features include a.c. interlock, flow-biased flux scram, reactor building isolation monitors in the vicinity of the fuel pool, containment spray interloch, ECCS pump flooding protection, testability of ECCS originating sensors,
-and diversification of sensors to open ECCS pump discharge valves.
i
'?)
\\:
=
l r
f
(
4 1
i j
R. S. Boyd '
(2) The applicant expressed reservation concerning requirements for containment inerting indicating that inerting would severely limit containment accessibility for inspection. However, NSP stated that it would agree to inerting the Monticello containment.
1 (3) It was noted that the standby gas treatment system filter banks are to be located in the same room with only six inches vertically separating the trains. We questioned the physical independency of this arrangement. The applicant's concern is with the design basis of any proposed physical barrier for separation.
I (4) GE stated that the loss of load transient with concurrent failure to scram study will be completed by early 1970.
(5) The design for the steam line isolation valve leakage rate was
~
discussed in regard to overall containment leak rate.
(6)
In regard to the analysis of radioactivity levels at the Minneapolis and St. Paul water intakes, we stated that the rimplified analyti-j cal model used does not appear to be conservative. We stated that l
ve would study this area further.
(7) The control room ventilation system will be isolated upon signals of high radioactivity. This results in a closed system in which the air is rectreulated but not filtered. At this time we are continuing our evaluation of this system.
4 Mr. T. Ippolito of DRL discussed certain potential problem areas 4
related to the instrumentation' and control systems.
Items which were discussed and the results of this meeting are set forth in a memo' f rom Mr. T. Ippolito to Mr. S. Levine dated October 1,1969.
R. S. Lee, Reactor Engineer Reactor Projects Branch #1 Division of Reactor Licensing Distribution:
Docket File RP Branch Chiefs RL Reading CO (2)
RPB-1 Reading N. Blunt D. J. Skovholt R. S. Lee S. Levine D. B. Vassallo R. C. DeYoung C. J. Hale f
f',
1