ML16340C112
| ML16340C112 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 05/18/1967 |
| From: | Woodard K US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Boyd R US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML16340C113 | List: |
| References | |
| REF-10CFR9.7 NUDOCS 8112020313 | |
| Download: ML16340C112 (20) | |
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~iM'OPY TO FROM Roger S.
Boyd, Assistant Director for Reactor Projects, DRL THRU:
Robert L. Tedesco, Chief Reactor Project Branch 2, DRL K. Woodard Reactor Project Branch 2, DRL D"'B: ~gy y 8 l967 S'
SUBJECT:
MINUTES OF MEETING WITH PG&E APRIL 20-21,
- 1967, TO DISCUSS DIABLO CANYON REACTOR " DOCKET NO. 50-275 On April 20-21, 1967,.representatives of Pacific Gas and Electric Company met with the staff and its consultants to discuss the Diablo Canyon plant design.
The following persons attended:
AEC AEC Consultants M. M. Mann, REG R.
L. Tedesco, DRL J. Newell, DRL M. Rosen, DRL K. Woodard, DR1.
R. Waterfield, DRL I. Spickler F. Schauer, DRL J.
E. Hard, CO W. J. Hall, Newmark
& Asso'c.
H.
W. Coulter, USGS L; M. Murphy, USC&GS PG&E Consultants J.
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Morrissey Kelly Schuyler Lindblad Shackelford Bettinger ters Crane J. A. Blume, Blume & Assoc.
P.
L. Horrer, Marine Advisors, Inc.
R.
H. Jahns, Stanford University S
W. Smith, Ca'ltech Westin house Westin house continued E.
S. Beckjord J.
Stadelman F.
M. Moschinf G. A. Harstead R. A. Wiesemann W. Bezella E. Paxton J.
W. Dorrycott R. A. Dean, R.
C. Nichols W. F.
Schmauss J. Moore Buy L.5'. Sniisq!.I 13orrrl!( Regrrln~% o0 fbi Pn)gaol/.SnIiu;>.~
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Q Seismic Desi n
The first topics discussed included the basis for, th6 magnitude of earthquake accelerat'ion proposed and the associated design response spectra.
J.
Blume detailed the approach used to.obtain the earthquake magnitude.
Basically, two methods are-applied which are based on empir-ical studies and take into account measured -conditions at the site such as shear velocity and density of the underlying material.
The results were compared with a third method proposed by Housner.
The overall results predicted an average of 0.13g 'with a worst case extreme of 0.25g for the "B" earthquake
- proposed, which would govern the containment design.
W. Hall commented that the methods used for this extrapola ion were only studies and were not intended for design use.
Dr. Blume agreed but believes that they do represent a realistic approach to assigning earthquake magnitudes.
For the close in (or "D" earthquake)
Dr. Blume predicts an acceleration of 0.2g;
- however, the design response spectrum proposed peaks in the short period range such that it does not govern the containment design.
Mr. Murphy stated that he would prefer 'that this earthquake not be considered to be so cl'ose to the site but should be "located further away since it originates as an after shock of an earthquake some distance from the site.
Mr. Murphy does agree with the 0.2g acceleration,
- however, he does not be'lieVe that the response spectrum would be much'ifferent than the "B" spectrum (which governs containment design ).
An important point which Dr.
Blume continued" to reiterate was that the foundation material, is good bedrock which is generally believed to result in less amplification of seismic waves.
In his opinion, if the plant were founded on alluvium the spectrum, could well be amplified by a factor of 2or 3.
'If In summary, it was agreed that the acceleration should be 0.2g for design and a maximum of 0.4g, but that the response spectrum proposed would need to be modified.
Dr. Blume stated that he would consider proposing a
revised spectrum.
We indicated that we would continue to study this prob-lem in light of the material received at thi's meeting.
~Geol o The applicant was requested to present a plot of the plant layout, locating the trenches and the known faults in relation to plant structures.
Dr. Jahns said that upon inspection of the trenching he had identified som minor faulting in the vicinity of the proposed.location for the containment foundation.
He does not believe that: these faults 'will reduce the strength of the bedrock as foundation material.
Both Drs. Jahns and Coulter believe that'hese f'aults are inactive and are more than 100;000 years old.
We
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t.',AY > 8 867 discussed the significant fault exposed at the seawall and established that it did not appear 'in an/ of t'e trenching in the vicinity of the foundation.
In Dr. Jahnss opinion, this larger fault does not run through the site but probably passes to the northwest; the visible smaller faults in the trenches could be branch faults of this larger one but are not of.concern to him.
It was established that if the containment were relocated (to move off of the small faults) it would probably lie on similar faults in the new location.
Thus, Dr. Jahns.concludes that the present proposed location is adequate.
They do not intend to do further trenching at the risk of uncovering geologic structures which could lead to additional speculation and possibly delay the pro)ect.
It was suggested that the exposed fault at the seawall be traced by furt'her trenching to establish its exact location in relation to the containment.
The applicant stated that they did not believe this was necessary and that further information of this type would. only complicate a contested hearing.
Dr. Jahns stated that none of these faults was similar to the Bodega or Malibu faults.
Dr. Coulter agreed with the statements and findings made by Dr. Jahns.
Tsunami The applicant's consultant on tsunami (Dr. Horrer) presented his method of estimating the maximum high and low water levels resulting from tsunami generate'd both close in and at great distances..
He stated that the particular characteristics of the small Diablo cove and ocean bottom would not amplify a tsunami.
These characteristics are based on calcu-lations and measurements of natural wave periods, observed at the site.
Diablo cove was compared Qfh tlat at Avila, a few miles south, where fairly large chan$ es in water level have been observed.
It was found that the response characteristics of Avila would result in amplitudes 3 to 10 times greater than Diablo cove.
In suanary, Dr. Horrer stated that in most cases large tsunamis can be explained by studying the
~ characteristics of the coastline.
He does not believe that Diablo cove has characteristics which could cause a, water level in excess of 18 feet above the mean low water level or a rundown of more.than 9 feet in the event of a tsunami.
I Mr. Murphy spoke on 'this topic and presented comments submitted by Gaylord Miller, a tsunami expert of the USC6GS.
Dr. Horrer stated that he could respond to.all of Mr. Miller's comments if desired.
We stated that Mr. Miller's comments would be submitted in a request for additional information.
Structural Desi n
Dr. Hall and F.
Schauer discussed the design of the containment and other structures with the applicant.
A list of 15 comments submitted by
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hlAY 1 8 1 g7 Drs.
Newmark and Hal.l (and supplied to PG&E prior to the meeting) served as the agenda for this discussion.
The significant topics discussed included:
(1)
The earthquake response design spectrum.
(2)
The dynamic analysis including damping factors to be used.
(3)
Design of isolation valves as Class I.
(4)
Stress limits on design of Class I equipment.
(5)
Local yielding in the containment due to thermal loads.
.(6)
Reinforcement patterns in various areas of the design.
(7)
Quality control and testing procedures.
(8)
Ultimate failure analysis We indicated that additional information would be requested in each of the areas discussed to confirm information obtained at the meeting.
Instrumentation and Control U. Moore briefly identified the areas in which he would probably require amplification concerning instrumentation, control and power systems.
No unique problems in 'this design area are apparent since these systems will be designed to the same criteria used for other recerit PWR's.
Turbine Missiles F~r Westinghouse stated that the low pressure turbine was essentially identical to that evaluated for other recent PWR's and failure would result in the same size and energy missiles.
We stated that we would ask for confirmation of this and an evaluation of the ability of the containment and control room to withstand the missile generated.
Plant S stems The design of the'arious plant systems was'iscusse'di.
Topics of this
'discussion included:
(1)
Loc'ation and protection of all Class I equipment.
(2)
Interior missile shielding.
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Radiation protection criterion in auxiliary. building (post accident).
(4)
'Containment access provisions during operation.
(5)
Motor cbntrol centers.
(6)
Ventilation systems.
(?)
Boron,injection system.
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(8)
Design details of 'diesel generators.
(9)
Leakage characteristics of the steam line isolation valves.
(10)
Isolation valve design and criteria - provisi'ons for testing, Thermal shock to primary system and reactor'vessel due to safety injection.
(It was agreed that a topical meeting would be set up.)
(13)
(14)
Control rod housing failure leading to failure of an adjacent housing.
I Design of system which will allow net load rejection.
Design for pipe whipping.
(15)
Desigh of core internals to withstand accident and seismic ioads.
We indicated that2additional information could be required in these areas.
Since this reactor is to have a power density 18% above that of Indian Poi.nt II, we pursued the coze physi'cs and thermal aspects of the design.
The increase in power is due to significant flattening of the 'flux both radially and axially but the linear heat generation has only varied from 18.5 Kw/ft to 18.9 Kw/ft.
According to Westinghouse, the new checker-board fuel arrangement does not contribute significantly to the flatter flux. It does,
- however, help to reduce peaking in the second core which is not a checkerboard configuration.
The reduction in axial peaking is due in part to the incorporation of "part rods" which serve primarily for coping with possible xenon oscillations.
The most significant reduction in the total peaking is due to a more than 10K reduction in the radial peaking factor.
Westinghouse claims'hat no physical 'core changes have been made to arrive at the new value, but that they feel'ore confident
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9 hiAY1 8 1967 about being able to achieve a power, shape below this design limit.
When q'uestioned about Indian Point II,, they'stated that without making any changes they could probably achieve the same flattening.
Judging from the conversation with Westinghouse, it appears that the problem (in their opinion) is not one of being able to achieve the flattening but rather the potential increase in probability of xenon oscillations due to the'increased power density.
The design of the
.part-ro4 for damping these oscillations was presented. There will be 8 such rods--two in each quadrant--and they will be in addition to the normal complement of control rods. 'he poison section will'o prise 3 f 3
oot length at, the bottom.
Westinghouse is not certain of the normal position of these rods at this stage of design.
The worth of an 'individ-ual rod will be less than 0.37; delta-k/k and they will probably be moved as a bank.
No reduction in positive moderator coefficient is expected as a result of using the part-rods.
The fuei enrichments" have been increased since the appl'ication was filed.
Since the application contain's no discussion of the part rods and other'spects of the core',
PG6E has agreed" to submit an amendment. describing the part rod system and the baiis
'or confidence in the design of the new core.
Clad Dama e Limits Fuel design was discussed and damage limits identified.
They expect the maxi'mum burnup to be 45,000 MWD/'ton and i't could be these rods which receive the highest thermal flux.
The fuel -is designed to the yield stress of 40,000 psi based on unirradiated Er-4, and for a total strain of 17.. The pellet; to-clad gap is -6.5 mils (cold),
a'nd the design is for 0-pressure cont ct a
the hot spot.
The gas release is, estimated to be 207. of the total s ure con act based on experiments'.
In terms of damage limits; a clad strain of 1.77. is considered to result in full,failure.
'Centerline melting-is'assumed to occur at 24 Kw/ft; failure is predicted at 28 Kw/ft.
At this po'int (28 Kw/ft) less than 307. of the fuel diameter would be molten.
We tried'o establish the basis for Westinghouse's confidence that at the transient overpower limit of 1127. or 21.3 Kw/ft there wou'ld be no signifi" cant fuel failure.
Westinghouse cited tests at Hanford and Chalk River which. provide confidence that bhere will-be no damage at this magnitude.
The standard Westinghouse elements will be tested in the Zorita reactor.
which is expected to be operational next year.. The design power of the
,Zorita test section will be 20 Kw/ft.
Westinghouse stated they would attempt to gain operating experience at '21 '
Kw/ft prior to operation of
'his plant.
We intend to explore this area further. based on the results of the TVA review.
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Boyd "7
Emer enc Core Coolin S stem Tile applicant stated that it would provide a core, cooling system capable of preventing core melting (calculated) for all break sizes.
These calculations would assume that no. adverse change in 'the core cooling configuration had taken place, such as rod bowing or.burs.ting.
Curves were presented showing water level as a function of time.
For the double ended break with 3 out of 4 accumulators operating
, the core bottom was covered in 18 seconds and the hot spot in 35 seconds.'ithout core cooling melting starts in 35 seconds; 75% of the tubes are calculated to burst at temperatures between 1250 F at pressures of about 1000 ps'i.
Westinghouse intends to do"clad bursting tests to investigate the effect of such f'ailure in regard to cooling.
The preliminary results did not assume a positive moderator coefficient.
The staff expressed its concern that all cases should be analyzed using the positive coefficient prior to the construction permit.
We indicated that juestions would be asked concerning core cooling.
Containment Desi n Basis Since the po~er density is higher for this case than Indian Point II for the same size and pressure containment, the margin of the containment is reduced.
In terms of the containment capability'urves developed for Indian Point II, the amount of metal-water reaction allowable would be reduced from 77% to 72% in 2000 seconds.
We discussed a new method of developing a containment capability curve in terms of energy.
A topical meeting will be held,to discuss this method.
Regarding the core transient assuming no core cooling, Westinghouse presented some irferesting results.
In terms of metal-water reaction with unlimited steam availability, following the parabolic rate eq'uation, the total reaction assuming the clad stands in place until 3375 F was 24%
and assuming the clad stands with 4800 F was'4%.
The total time for all of the clad to slump was 1000 seconds.
In previous calculations it had been assumed that the reaction was steam limited b'ased on the supply of steam available from slumping fuel into the water below the core.
The amount of reaction reported was only'slightly less than the unlimited case.
Thus, in their model for containment pressure transients (used for all Westinghouse PWR's) the core is only slightly steam limited.
En ineered Safet S stems It was learned that several changes
~ have been made in the cooling ~ater systems for safeguards since issuance of the PSAR; The basic change was.'to move the fan-coolers from a. separate coolant loop to the component cooling loop which aleo supplies the residual heat exchangers.
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- y. MAY 1 0 1967 this set-up; a failure in the component loop could preclude core and containment cooling altoghether after che first 45 minutes of an accident.
lt was strongly urged that some sort of a backup cooling system be pro-vided for both fan-cooler and residual heat exchanger cooling water.
'ith regard to the thiosulfate injected containment spray system, there appear to be many characteristics of the system which are untried and will require development work.
Significant items include:
(1) method of'preventing mixing of the water which is used to
'force thiosulfate out of its storage tank (2) effect of particulates on spray effectiveness (3) possible discrepancy in applicant's calculated removal effi-ciency due to pressure e'ffects (4) possible coaleacense of water. droplettes (5) relocation of spray nozzles in a positi6n where better mixing would take place.
The fan-coolers will be qf the finned type and we indicated that justifica-tion similar to that given for the CPL case would be necessary.,
We indicated that questions would be generated concerning safeguards systems.
Safet Evaluation Dose calculations for various accidents were discussed.
Westinghouse seated that there was a pis take in the reported
- doses, however, the difference was not significant.
We indicated that we would require more detail's concerning the steam line break accident.
J.
Moore stated that this could be provided for the no stuck rod case but not for the stuck rod case since this would require a more complete core design than now exists.
We stated that the results of this calculation were required to assess the necessity for containment isolation in the event'f steam line break since fuel failure will occur.
Westinghouse stated that the new core design would not significantly affect other reactivity accidents such as rod ejection, rod drop or positive moderator effects.
They were informed that we ~ould require an evaluation of the reactivity effects due to shaking and fuel relocation ih the event of an earthquake or MCA.
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- 9 MAY18 1967
~Summa r At the conclusion of the meeting we indicated that the following course of action would be taken:
(-1)
We would expect an amendment to be submitted soon concerning the new core and part-rods, (2)
We would generate questions relating to the site and structural design which would be discussed with the applicant prior to
. issuance, and (3)
Questions in the other areas would follow later.
Distribution:
Suppl.
DRL Reading RPB 2 Reading Orig:
KMoodard H. H. Mann P. A. Norris Assistant Directors, DRL Branch Chiefs, DRL K. Kniel R. Materfield I. Spickler F. Schauer J.
E. Hard, CO 1KL/RP 'RL/RP Kazoo
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n DISTRIBUTION OF BOARD NOTIFICATION
~Di bl I
Atomic Safety and. Licensing Appeal Board Atomic Safety and Licensing Board Panel Docketing and Service Section Hrs. Elizabeth Apfelberg Andrew Baldwin, Esq.
Richard E. Blankenburg Hr. Glenn 0. Bright Herbert M. Brown, Esq.
Dr. John H. Buck Philip A. Crane, Jr.,
Esq.
Hr. 'Frederick Eissler David S. Fleischaker, Esq.
Mrs. faye Fleming Arthur C. Gehr, Esq.'.
Bryon 'S. Georgiou
~ Mark Gottlieb Mr. Richard. B.,Hubba rd Dr.
W.
Reed Johnson
- 'Janice E. Kerr, Esp.
Dr. Jerry Kline Mr..John Harrs Thomas S.'oore Bruce Norton, Esq.
'oel R. Reynolds, Esq.
Mr. James
- 0. Schuyler Mr., Gordon Sil ver Hrs. Sandra
'A. Silver Paul C.. Valentine, Esq.
Harry M. Willis John F. Wolf, Esq.
ACRS Members Mr. Myer Bender Dr,. Hax W. Carbon Hr. Jesse C., Ebersole Mr. Harold Etherington Dr.
- Wi'1 1 i am Kerr Or.'arold W. Lewis Dr. J.
Ca'rson Hark Hr. William H. Hathis Dr.
Dade W. Hoeller Dr. David Okrent Dr. Mil.ton S. Plesset Hr. Jeremiah J.
Ray Dr. Paul G. Shewmon-Dr. Chester P. Siess Hr. Davis A. Ward
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