ML19329A558
| ML19329A558 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 09/24/1970 |
| From: | Schwencer A US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8001070556 | |
| Download: ML19329A558 (6) | |
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September ?4,1970 R. C. DeYoung, Asst Dir, PWRs, Division of Reactor Licensing TilRU:
Charles G. Long, Chief, PWR Project Branch 2, DRL /
l NOTES ON t.CRS SEPIEMBER 17, 1970 MEETING 0:1 OCONEE, DOCKETS 50-269, 50-270, AND 50-287 Executive Sess1~2 Copics of ELCS Amcidment No. 21 were mada available to the Full Committee (just filed by Duke).
i Staff Session t
Project Leader, using viewgraph, identified items resolved since August Full Committee meeting and items resolved since September 9 Subcommittee meeting.
Mr. Long told the Committee that the etcff had rcviewed a draft of Amendment No. 21 and we now considered the ECCS revicu on Oconee com-plete for licensing purposes.
Dr. Rcsen informed the Committee that he considers the core coolable, although he does not agree with the consensus a
of the people who attended the INC meeting in August that the RELAP-3 work is an adequate basis for such a conclusion.
We also told the Committee that hydrogen control, if required by the staf f, will be on the backfit rule basis. We are expediting our review of this but.do not intend for it to delay the licensing procedure.
We also told the Committee that we are approximately 80% complete in our tech spec review and that we expect to have a complete draf t in about a month and a half.
We informed the Committee that B&W's diverse reactor trip for use with ECCS is unacceptable but see no practical problem in getting an acceptable diverse trip (low reactor coolant flow, or high containment pressure).
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2 The Committee asked a number of questions.
1.
Spent Fuel Pool Doses - Staf f Position.
Mr. DeYoung stated' that either filters or fuel pool water partition
-factor credit are expected to reduce doses at Oconec to an acceptable level for the fuel handling accident (30 Rem 2-hour thyroid dose with addition of filters or 20 Rem 2-hour thyroid dose with additional water partition credit). Both filter and partition credit will not be required.
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2.
Containment-Pressure Margin Philosophy i
We stated that at CP approval containment had a 9-1/2% margin.
That identification of the steam generator F. W. ring failure potential essentially used up that margin. We also stated that it is our posi-tion with current applicants to require a 10% margin based on secondary system being designed not to fail. We said state of construction at Oconee Units 1, 2 and 3 preclude design changes to significantly in-crease design pressure.
3.
Sing 1'e-Loop ' operation - Manual Reset of Trip Points In addition to assuring the Committee that single-loop operation _will not be permitted until tests are performed, ve told the Committee that manual reset of trip points with the reactor shutdown were acceptable in converting from two-loop to one-loop operation.
Single pump operation will not be licensed.
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New Regulatory Criteria Since CP Review That Might Be Imposed on Units 2 And 3 Mr. Long responded by staIing that Duke has revised their plant design to accommodate a majority of the new criteria that we presently invoke 9
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3 on new applicants such' as In-Service Inspection, B31.7 piping require-ment, etc, and that we could only find two criteria they do not or may not meet:
2 (1)
The reactor cavity has been designed to withstand a 8.5 f t break without loss of flooding.
While today we would require ultimate structural capability to withstand a 14.1 f t break.
Although the Duke design's ultimate capability is larger than 8.5 ft we have not required it to be evaluated at 14.1 ft Dr. _ Siess commented that additional reinforcing steel in the t
cavity concrete structure could probably add significant i
additional withstand capability.
(2)
Containment pressure 10% margin for unknown energy sources.
Mr. Long stated that at the CP stage we had close to this (9.5%).
Construction is too far along to significantly regain this margin,on Units 2 and 3.
Applicant Session Bill Lee made a plea for one letter covering all three Oconee units.
B&W presented their ECCS data and discussed why they were not ready at the September 9,1970 Subcommittee meeting.
The key breakthroughs that resulted in Amendment 21 were (1) verification that ASME steam table equations are valid above 2500*F, (2) simplification of core model (reverted back to modeling a hot channel instead of a hot bundle), and (3) decision that all volumes could be considered homogeneous.
In response to ACRS
-5 questions, C. Parks said use of a +0.9 x 10 positive moderator coefficient would result in.about a +25*F rise in peak fuel temperature during the accident.
Dr. Isbin commented that assumption of a high heat transfer coefficient early in the blowdown might not be conservative if it caused steam blanketing.
C. Parks noted that the vent valves in the Duke vessel would prevent steam binding.
Dr. Okrent asked about fuel blockage effects e
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C. Parks referred to Governnent laboratory tests.which suggest such blockage actually may reduce f uel temperature but that this is not well understood.
In. response to Dr.- Okrent's questions, B&W stated that thermocouples in Oconec Unit 1 are expected to last for 5 years and Duke said they will keep them in the~ core.
While the containment penetration and plant computer for Units 2 and 3 are not designed to accept TC's in the core, the ' reactor pressure vessel instrument penetrations (in-core flux monitors) are available.
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Dr. Okrent probed Duke on their commitment and activity in seeking a workable in-service vibration monitoring technique to detect loose core in ternals.
Duke said they are actually looking, will welcome information, but have found nothing to date to do the job.
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Dr. Stratton asked if Duke intended to use (or had capability to use caustic mix tank invet. ory to control spray pil to reduce iodine in con-tainmen t. _ Duke responded by saying they are following Battelle work which indicates dose reduction of 4 to 5 for acid sprays.
On Radioactive Waste Release Management Duke stated they intend by administrative procedures to releese at 1% of Part 20 for both liquids and gases. Liquid release will be based on 30 cfs tailrace dilution with no credit for hydro plant operation.
They stil1~want 10% Part 20 for Tech Specs, however, which is at odds with the staf f position expressed to both Duke and the ACRS (1% of Part 20 except 100% Part 20 for brief intervals of approximately 15 minutes to handle unusual emergencies).
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4 5-B&W presented their case for the power-to-f-low scram as the diverse reactor trip for use with ECCS.
They stated orally that it would with-stand the accident environment for 35 seconds. Under questioning, they could.not give assurance that, for breaks between 0.4 and 5 f t, fuel peak' ten.peratures lwould remain low (on the order of 1700*F).
Bill Smith indicated that B&W was not willing to test the flux detectors for 35 seconds to demonstrate ability to withstand thin environment.
Duke stated that they had measured compressive and tensile strength of test cylinders of the Oconce Unit No. 1 dome concrete and obtained,
28-day strengths of 5838 to 7428 psi and 525 to 674 psi, respectively.
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Dr. Siess questioned whether the "Soniscope" technique used on the base slab at Turkey Point had been considered as a technique to probe for
. voids or delaminations.
Duke said they will "do anything reasonabic to assure' a safe building" and that to date they had vigorously pursued this matter with no basis to conclude fincy have a problem similar to the i
Turkey Point problem.
r The Committee inquired about the use of Fracture Toughness in determining stresses in the reactor coolant system during heatup and cooldown.
Duke said th'e staf f had made them aware of a concern in this area and they will work with us to resolve the matter in the Tech Specs.
.Dr. Okrent asked about doubling the relief capacity of the pres-surizer safety valves.
B&W said major rework would be required of some if not all affected components--the pressurizer nozzle size or quantity would have to be increased and the quench tank and quench tank cooling system would have to be enlarged.
Dr. Okrent asked if B&W could think of ways to more rapidly inject horon into the core following a LOCA.
B&W responded that one obvious cone'pt that' might be examined is the Westinghouse scheme of adding a pressurized tank,of high concentration boric acid in the high pressure injection line.
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6 On the ATWS. schedule, Bill Smith of B&W stated tha*. they were
' awaiting: further guidance from the regulatory staff before proceeding
. with analyses which, prohibit control rod motion.
Post Caucus Af ter caucus ACRS Chairman, Dr. liendrie, stated the Cormnittee expected to be able to write a letter which would have a number of statements including one on the remaining documentation on B&W's ECCS analysis.
The. letter will cover Unit 1 only.
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A. Schwencer PWR Project Branch 2 Division of Reactor Licensing
Enclosure:
Attendance List Distribution:
Dockets (3)-
.DRL Reading PWR-2: Reading P. A.' Morris-
'F. Schroeder T. R. Wilson R.' S. Boyd.
R. C. DeYoung D..Skovholt E. G. Case,.DRS R. R. Maccary Compliance (2)
DRL, DRS Br. Chiefs
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A..Schwencer F. W. Karas-(2)-
R. W. Klecker O
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~ ATTENDANCE LIST OCONEE-ACRS MEETING, SEPTEMBER 9,1970 Duke Power Company _
Bechtel' James Wyatt-Hampton
' Martin NMN Malcom Lionel NMNlLcwis
- William Oscar Parker,~ Jr Warren !!crbert Owen, Jr, AEC' Paul llodges Barton S. H. Hanauer, DR i-Austin Cole-Thies P. A. Morris, DRL William States Lee F. Schroeder, DRL -
Charles JoscPh Wylie R. C. DeYoung, DRL Linwood Clayton Dail C. G. Long, DkL
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Carl Amos Price A. Schwencer, DRL Kenneth Sink Canady-p, F. Ross, DRL
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' John Edwin Smith T. M. Novsk, DRL I
Joseph Earl Biesecker O. D. Parr, DRL i
t Edwin. Dean.Powell P. W. Howe, DRL Thomas Fulton Wyke E. G. Case, DRS A. W. Dromerick, DRS V. A. Moore, DRS 339
- 11.. Rosen, DRS 1
John Mcnry.MacMillan J. Knight, DES,
=i William John Schermer.
F. P. Schauer* DRS Elbert O'Neil Hooker M. B. Fairtile, DRS William Henry Spanglar R. J. Colmar, DRS Richard Nathaniel Edwards, Jr M. S. Dunenfeld, DRS GeorgefEugene Kulynych_
- 11. J. Richings, DRS James Francis Mallay H. Specter, DRS Donald Wheaton Montgomery S. S.'Pawlicki, DRS
. Charles Evann Parks C. E. Murphy, CO, Region II William Reuben Smith ~, 3rd Rudy Vaughn Straub -
Herbert. Lewis :Helmbrecht -
Daniel Franklin Levstek Robert Allen Turner O
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