ML19312C749
| ML19312C749 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 07/11/1967 |
| From: | Grimes B US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Long C US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7912190960 | |
| Download: ML19312C749 (6) | |
Text
YY3, n
C'*..:<,.'~l*,l.*..e UNITED STATES GOVEP3 MENT Memorandum To Files 4 DATE:
July 11, 1967 THRU C. Long, Chief, RPB 93, DRL FROM :
B. Grimes, Reactor Project Branch No. 3 Division of Reactor Licensing StJBJECT:
ACRS Subcocimittee Meeting on Duke Power's Oconee Units 1, 2 and 3 Cn June 23, 1967, we and the applicant met with a %subcocmittee of the ACRS to discuss the Duke Power application for three units in Oconee County, South Carolina. Topics of discussion included the thermal design, control rods, instrumentation, and answars to ACRS questions which were submitted in Amendment No. 5.
The applicant 's attendance list is attached.
Attendance from staff and ACRS was as follows:
DRL ACRS R. Boyd C. Zabel C. Long S. Hanauer B. Grimes Stratton D. Sullivan A. O' Kelly C. Fischer R. Wilcox, Staff A.
Instrumentation The instrumentation of the station was discussed in some detail and the following points were made.
(1)
A single bus now energizes the rod drive clutches. The applicant should consider splitting the bus even though it would take two failures to keep the single bus energized.
(2) The proposed instrumentation is a new line and special attention should be paid to proof-testing the integrated systems.
(The appli-cant outlined the plans for mocking up the instrumentation and stated that it would be delivered early to the first unit to enable extensive in-place tests.)
(3) The applicant stated that trips were powered from the vital bus rather than from " source" as shown on Fig. 7-2.
(4)
The interactions between units as a result of controls being connected to vital buses (which are shared) should be examined.
(5) Means for diversifying the engineered safeguards signals should be examined as the design progresses.
(*4e agree with the subcommittee's
(*
concern and will pursue this point in future applications.)
s 5
Buy U.S. Savings Bonds Regularly on the Payroll Savings Plan O 9121 oo Jgo
(6) There are three independent instrument air systems, thus avoiding interaction in this system.
(7) The need for redundant control of switchyard breakers should be examined.
(It is not clear that this should be required since power would still be available from the 13.8 kv or 100 kv lines.)
3.
Control Rods The applicant stated that the proposed rack and pinion design had been compared with the BONUS design and that they felt that many problems noted at BONUS had been eliminated by their design. They also stated that a trip to the BONUS reactor was planned to discuss operating problems with the operating staff. The applicant stated that sticking was not expected, that these racks were heavier than previous designs and that a test rig had been misaligned by 120 mils before sticking had occurred (spec. is 10 mils).
Dr. Hanauer noted that he was concerned with the rack and pinion design because there had been many operating problems on previous designs. The applicant quoted test data already obtained to substantiate the opera-bility of the drives.
The Subcommittee inquired what the consequences of stopping seal water flow would be (the reactor could still be scrammed) and suggested the possibility of splitting the seal water system.
In response to questions on what effect dropping a control assembly rack onto the core would have, B&W str.ced that this test had been performed and only minor damage resulted.
C.
Answers to ruestions Asked at the June ACRS Meeting The following subjects were to be orally discussed and are numbered as listed in the ACRS question list transmitted to Dr. Morris by memo dated June 12, 1967.
(1)
If an accumulator line (14 in diameter,1.1 ft ) broke, the single accumulator remaining would be sufficient to recover the core and the peak fuel temperature would be 900 F.
(2) Check valves on the accumulators would be tested for operability during refueling and a continuous leak test would be available by monitoring the level in the tank. Accumulators would not be valved of f unless future analyses showed that one accumulator would be sufficient.
(3) The irradiation surveillance program will include at least 20 speci-mens per tube and four tubes per reactor (this is similar to other PWR's).
The physical inspection schedule has not been set.
6
(4)
Initiation signals of engineered safeguards will be considered but not in detail at this time.
(5)
Dilution of the water in the containment by fresh water leaks was considered extensively in question 7.4 of Supplement No.1.
At least 40 minutes are available for isolation under the worst condition assuming that no control rods scram.
(6) On the rod ejection accident several questions were asked and answered on the significance of flow and rod patterns on the results obtained.
i (7)
A 27. radiographic inspection of liner welds is considered acceptable since it is a check on the work of the welder. The higher stresses expected during accident canditions would tend to close leaks.
(3)
Bowing of fuel during a rod ejection accident was considered by increasing and decreasing the space between fuel bundles in an infinite lattice. The maximum reactivity insertion was found to be cbout 0.27..
(9)
B&W feels that its present computational model is adequate to predict fuel behavior during transients at '.ne end of life but that properties of the clad (creep rate and strain rate) are unknown. These parameters will be obtained through the B&W high burnup program. There is presently no program in the industry to actually perform transient tests with high burnup fuel.
(10) The detection of primary system leaks was discussed. The applicant stated that operation of the sump in the containment could detect i
about 75 gal / day but that the best method was "a man looking" (for condensation) inside the containment.
Other subjects discussed were the thermal transient experienced by the vecsel on cold water injection, allowable stresses on vessel internals dur-ing blowdown, design of the underwater weir, and core cooling analyses.
These subjects are discussed in our Addendum to Report No. 2 to the Committee on Duke. The following questions were posed by the subcommittee on these subjects:
(1) What effect will pressure loadings have on propagation of cracks in j
the ductile region?
( Answer - Not significant, if pressure is only a few hundred psi since thermal stresses are very large.)
(2) What effect will a break in a high pressure injection line have on the analysis?
( Answer '- The broken line would have to be manually isolated.)
(3) What is the worst break in terms of (1) positive reactivity insertion i
and (2) peak clad temperature? (Based on further discussions with the applicant it appears that the smaller breaks have a worse reactivity insertion--if rods do not scram--but the insertion is ever a longer.
time period and the peak clad temperature is therefore reached during the largest break.)
L
-4 (4)
Is there a leak that, if the high pressure system did not operate, could cause the pressure to hang up and allow the core to melt? This is to be answered at the full committee meeting, but on the basis of discussion with the applicant, it appears that,it is doubtful if there is such a break. For example, for the 0.05 ft-break the top of the core would not be uncovered if the high pressure system worked and would be only uncovered only a few feet if the high pressure system were inoperable.
A " hang-up" of pressure with low water inventory is more likely to occur in a system without accumulators (since the accumulators actuate at 600 psi and a low pressure pumping system would become effective at about 250 psi or lower).
(5) The staff was asked to have a consultant look at the design of the underwater weir for the July meeting. We will receive a report from Dr. A. J. Hendron of Dr. Newmark's staff based on the dimensions given in Supplement 5 and on oral information obtained from the applicant.
The subcommittee suggested the following agenda for the July ACRS meeting with about 20 minutes being devoted to the spectrum of breaks analysis and a total of 40 minutes to the other items listed.
?RESENTATICN 1.
Capability of the emergency core cooling systems to cope with all coolant line break sizes.
Including, to the extent poss'ible, the temperature and pressure history of the breaks.
Present what each subsystem can do in terms of break sizes (a bar chart similar to
' G.E. was what the subcommittee had in mind).
Present the effect of the positive moderator coefficient over the spectrum of breaks.
2.
Clarify limits on stresses on clad internals during blowdown with respect to ASME Code stress Ibnits.
3.
Solution to the steam bubble problem (also discussed in our Addendum to Report No. 2 to the ACRS).
4.
3rief presentation on rod drives.
5.
Instrumentation, including (1) incaraction between units from sharing the vital busec and (2) diversity in ECCS signals.
6.
Crack propagation during thermal shock of vessel for various rates of injection and for extra pressure loadings.
7.
Thermal Jesign (DN3 correlation and experimental program).
8.
Justification for lack of isolation valves in the steam line.
- 5 -
presentation:
For discussion but 1.
Underwater weir 2.
Valving off. accumulators during operation
{
3.
Containment external inspection 4.
3owing of fuel rods during blowdown.
i Attachment
)
D. Muller R. Tedesco C. Long i
R. Ireland M. Rosen R. DeYoung V. Moore J. Newell
- 3. Grimes i
n k
[
i i
1 l
t J
e-yy n..
.m.-t 9
,.-w.
.,y pr3 y
,p r%-=
c-sw,-
ATTENDANCE - ACRS SUBCOMMITTEE MEETING - 6/23/67
-Bechtel Corporation
. Duke Power Company William. States Lee *.
Pierre R(only) Cassidy.
Linwood Clayton Dail *~
John James Tkacik Charles: Joseph Wylic
- Robert Clark Williams Edward Castle Fiss
- Howard Wayne Wahl Warren Herbert Owen
- Edward Joseph Simanek Bill Morrell Rice
- Jack Emmet Reilly Carl Amos Price Martin (None) Malcom Thomas Fulton Nyke
- Roger Franklin Griffin Stanley ~Ellman Nabow
- Harvey Fishel Brush Robert Lacy Dick William Kenneth Doe John Clemet Rogers George Hobart Bosworth William Humphrey Grigg Babcock & Wilcox Company-Consulting Attorney Donald Wheaton Montgomery
- Roy Baker Snapp
- George Eugene Kulynych
- Alan Hillel Lazar
- Robert Elmer Wascher
- James Harry Taylor
- Melvin Francis Sankovich
- Howard Hartman Stevens
- Herbert Edward Flora
- Thomas McKinley Schuler, Jr
- Eennet Beckham Cardwell, Jr
- John Henry Kraps
- Howard Frank Dobel *
- Q Clearance
~
ms