ML13302B178
| ML13302B178 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon, San Onofre  |
| Issue date: | 09/15/1981 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Atomic Safety and Licensing Board Panel |
| Shared Package | |
| ML13302B177 | List: |
| References | |
| NUDOCS 8110190018 | |
| Download: ML13302B178 (11) | |
Text
MEMORANDUM FOR:
Atomic Safety and Licensing Board FROM:
Robert L. Tedesco, Assistant Director for Licensing, DL
SUBJECT:
BOARD NOTIFICATION -THERMAL SHOCK TO PWRREACTOR VESSELS (BN 81- )
Reference:
Memorandum, D. G. Eisenhut to Atomic Safety and Licensing Boards for PWRs, dated May 8, 1981, On May 8, 1981, we informed the Atomic Safety and Licensing Boards on PWRs of the results of our preliminary review of therjual shock.to PWR reactor vesses.
At that time we concluded that no immediate lfcensing actions are required for plants under construction, plants under review for construction permits or operating licenses, or operating facilities.
Since that time we received 'additional information on this subject which has been evaluated as discussed in the attache d memorandum from T.- Novak to D. Eisenhut, dated September 15, 1981. This new information does not alter our conclusions presented in the May 8, 1981 memorandum.
Xgonalsigned b Robert L. Tedesco, Assistant Director for Licensing Division of Licensing
Enclosures:
- 1.
Memo to D. Eisenhut fm T. Novak dtd 9/15/81
- 2.
Memo to ASLB fm D. Eisenhut dtd 5/8/81 cc:
See next page 8110190018 810930 PDR ADOCK 05000275, A
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.1981-335-960 NRC FORM 318 (10-80) NRCM 0240 OFFICIAL RECORD COPY SP:183596
DISTRIBUTION OF BOARD NOTIFICATION (THERMAL SHOCK FOR PWR REACTOR VESSELS)
Diablo Canyon ACRS Members Dr. John H. Buck Mr. Myer Bender Philip A. Crane, Jr., Esq.
Dr. Max W. Carbon Mr. Frederick Eissler Mr. Jesse C. Ebersole David S. Fleischaker, Esq.
Mr. Harold Etherington Mrs. Raye Fleming Dr. William Kerr Arthur C. Gehr, Esq.
Dr. Harold W. Lewis Bryon S. Georgiou Dr. J. Carson Mark Mark Gottlieb Mr. William M. Mathis Mr. Richard B. Hubbard Dr. Dade W. Moeller Dr. W. Reed Johnson Dr. David Okrent Janice E. Kerr, Esq.
Dr. Milton S. Plesset Dr. Jerry Kline Mr. Jeremiah J. Ray Mr. John Marrs Dr. Paul G. Shewmon Thomas S. Moore Dr. Chester P. Siess Marjorie S. Nordlinger Mr. Davis A.. Ward Bruce Norton, Esq.
John R. Phillips, Esq.
Mr. James 0. Schuyler Mr. Gordon Silver Mrs. Sandra A. Silver Atomic Safety and Licensing Paul C. Valentine, Esq.
Board Panel Harry M. Willis Atomic Safety and Licensing John F. Wolf, Esq.
Appeal Board Panel Mrs. Elizabeth Apfelberg Docketing and Service Section Andrew Baldwin, Esq.
Richard E. Blankenburg Mr. Glenn 0. Bright Herbert H. Brown, Esq.
San Onofre A. S. Carstens Phyllis M. Gallagher, Esq.
David W. Gilman Dr. Cadet H. Hand, Jr.
Mrs. Lyn Harris Hicks Mrs. Elizabeth B. Johnson James L. Kelley, Esq.
Janice E. Kerr, Esq.
Charles R. Kocker, Charles E. McClung, Jr., Esq.
David R. Pigott, Esq.
Alan R. Watts, Esq.
Richard J. Wharton, Esq.
0 September 8, 1981 SECY-81-286A POLICY ISSUE (Information)
For:
The Commissioners From:
William J. Dircks Executive Director for Operations
Subject:
PRESSURIZED THERMAL SHOCK OF PRESSURE VESSELS
Purpose:
This paper discusses recent staff actions concerning the issue of pressurized thermal shock of reactor pressure vessels and outlines the present plans for dealing with the issue on operating plants.
Discussion:
In an earlier paper (SECY-81-286 dated May 4, 1981), the staff outlined the technical aspects of the issue of pressurized thermal shock, provided the basis for the conclusion that no immediate licensing actions were required for operating reactors, and discussed actions being taken by the staff and licensees to deal with the issue.
On July 28-30,
- 1981, the staff met with Babcock and Wilcox, Westinghouse and Combustion Engineering Owners Groups to present the staff's view of the problem and to discuss the progress of the Owners Groups' activities since the previous meeting in April.
The meeting minutes are included as Enclosure 1.
The staff views presented at the meetings were the following:
- 1.
Efforts should continue to reduce the probability and severity of overcooling transients.
- 2. Reliance on operator action to prevent repressurization is not an acceptable long-term solution to the problem.
- 3. An upoer limit should be established for the pressure vessel reference temperature for nil ductility transition (RTNDT) beyond which operation would not be permitted.
The B&W Owners Group has continued with the analysis program described in their response of May 15, 1981.
They stated
Contact:
Thomas E. Murley, NRR 49-27517
The Commissioners
-2 that a preliminary analysis using realistic assumptions for a small-break, loss-of-coolant accident (SBLOCA), showed that the Oconee-1 vessel could safely sustain the 5BLOCA after 32 effective full power years (EFPY) of operation. This analysis included consideration of plant-specific information on weld locations, material chemistry and fluence and used two dimensional calculations of heat conduction in the vessel; whereas, previous generic calculations were one-dimensional.
The analysis also assumed that the operators take corrective action to prevent repressurization of the vessel.
The staff reiterated that reliance on operator action is not an acceptable long-term solution. The B&W Owners Group schedule for completion of plant-specific analyses is the following:
- a. Oconee 1 -
December 31, 1981;
- b. Rancho Seco -
March 1, 1982;
- c. Other plants - later in 1982 The Owners Group committed to have their Materials Subcommittee meet with the staff to discuss the technical issues in more detail.
This meeting has been arranged for September 23, 1981.
The Westinghouse Owners Group presented the status of their generic studies, the scope of which has increased beyond tha-t outlined in their May 15, 1981 response. Their plan is to submit the generic analysis by December 31, 1981, after which they would perform plant-specific analyses.
The Owners Group reiterated their assertion of last May that all Westinghouse plants can safely sustain severe thermal shock transients, including repressurization, to beyond January 1983, at a minimum.
A meeting has been arranged for September 18, 1981, to discuss the technical issues in more detail.
The Combustion Engineering Owners Group outlined the generic analysis they are scheduled to submit by December 31, 1981.
They also stated that results to date supocrt their previous assertion that the most limiting.CE plants can safely sustain the most severe overcooling transient (a steam line break) for approximately 5 more EFPY. A meeting has been arranged for October 7, 1981, to discuss the technical issues in more detail.
No new information has come to light that would alter the staff's conclusion that no immediate licensing actions are required for operating reactors.
However, because the implementation of any proposed fixes or remedial actions must allow for adequate
The Commissioners
-3 lead time, letters were sent to the licensees of eight plants requesting further information to enable the staff to assess what actions may be required to resolve this issue.
The eight plants (Ft. Calhoun, Robinson 2, San Onofre 1, Maine Yankee, Oconee 1, Turkey Point 4, Calvert Cliffs 1, and Three Mile Island 1) were selected on the basis of their current vessel irradiation history, materials properties, and their plant system characteristics. A sample letter is included in.
The owners of these reactors have been asked to submit information within 60 days regarding the current reactor pressure vessel toughness, the rate at which fracture toughness is being and has been reduced, the licensee's recommendation for a limit on fracture toughness reauction beyond which operation should not continue, actions which reactor operators could take to lessen the effects of pressurized thermal shock, and how such actions are incorporated into operating procedures and training programs.
The eight licensees also have been asked to supply, within 150 days, additional plant-specific information on vessel materials, neutron fluence calculations and-measurements, and transient analyses that will be used by the staff in its independent evalu ations.
We also requested information on long-term corrective actions which could be taken for their plants.
These include:
- 1. reduction of irradiation damage at the reactor "beltline" by replacement of outer fuel assemblies with dummy assemblies or other fuel management changes;
- 2. reduction of thermal shock by increasing the temperature of emergency cooling water;
- 3.
recovery of reactor vessel fracture toughness by in-place annealing; and
- 4.
design of a control system to reduce the potential for initial thermal shock and control repressurization of the reactor vessel.
The staff will meet with the Owners Groups again in the coming months and will review the generic reports scheduled to be submitted at the end of the year, as well as the plant-specific
The Commissioners
- 4 information requested in the letters to eight licensees.
The staff will brief the ACRS on this issue on September 11, 1981.
We will keep the Commission informed of the progress of these reviews.
William J. Dircks Executive Director for Operations
Enclosures:
- 1.
Meeting Minutes
- 2.
Sample of Letter to Licensees
ENCLOSURE 1 UNITED STATES 71 NUCLEAR REGULATORY COMMISSION WASHINGTON, 0. C. 20555 AUCUST-le Docket No. (All Operating PWRs)
Licensees:
B&W, Westinahouse & CE Owners Groups
SUBJECT:
SUMMARY
OF MEETINGS WITH THE BABCOCK & WILCOX, WESTINGHOUSE, AND COMBUSTION ENGINEERING OWNERS GROUPS ON JULY 28, 29 AND 30,
- 1981, RESPECTIVELY, CONCERNING PRESSURIZED THERIMAL SHOCK TO REACTOR PRESSURE VESSELS (RPV).
Introduction The meetings were held in Bethesda, MD at the request of tha NRC staff in order to
- 1) present, briefly, the staff's analysis of the problem and the actions the staff intends to take and 2) to hear, from the ?WR owners groups the results of their analyses to date and their proposed actions concerning the problem. The meeting followed the published agenda,.
The attendees for each meeting are identified in Enclosure 2.
Visual aids for the staff's presentation are included in Enclosure 3.
Visual aids for the owners groups' presentati are included in £nclosure 4 (3&W), Enclosure S (lestinghouse), and Enclosure.6 (CE).
Summarv of the Staffs Presentation The staff has reviewed the owners groups responses of M'ay 15 and :ne Ticensees' rasconses o-May 22, "981 to our letter dated Aoril 2, 1981 concerning :ne issues.
As a result of these reviews and tne staf' s independent review of the concern, the staff has concluded that:
S. Efforts should continue to reduce the probability and severity of overcoolino transients.
- 2. Reliance on o:perator action -o prevent repressurization is not an acceptable long term resolution.
- 3.
n upper limit should be established for RT for continued opernaion.
es ar o.,0 as ccncluded that, for plants aher? the reactor oressure vessels have reached or are approaching -he threshold refernced teomperature s:a-ed in 10 CFR 50, Aooendix ' PV C, action is needed now to begin resolving the long term problems.
The plants involved include the six olants which have the highest R7 Values.
This conclusion is based in part on the fact that any 9Irposed corrective action must allow adequate lead time for planning, review, aooroval and ?rocurement.
Accordingly, the staff intends to request aororiate action by the six Piants and the staff -xpcecs the owners group oarticipation. in tre resolution of these concerns.
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7/23'0/31 iimiting plant for the next five EFPY.
CE stated that they prefer to use racture mechanics in the analysis rather than RT data.
No engineering analyses have yet been performed to assay any of '.
suggested (or any other) remedial measures but CE will provide solutions within the 5 EFPY margin they have established. Currently, operators are instructed to achieve 500F sub coling in a LOCA event and they may discontinue HPI under guidelines cro vided.
The statements found in some CC submittals that no opocrator action" is expected in some emergencies was qualified to mean:
none beyond orescribed orocedures.
The most limiting event for CE tlants is theo Lb aos was sta ed
- n t-Ar i 4RC meeting.
The analyses aim at both crack initiation and arrest wtn the final condition of cracked with no RPV wail penetration, preserving vessel integrity, being judged acceptable. The fracture mechanics analyses Ollow essentially the same method as is used by ORNL and the NRC staff excapt tnat the computer program calculates the J-integral rather than the stress ntensity factor.
it was agreed that a meeting will be held in September or
- October, 1981, to update the NRC on the technical progress in the CE orocram rd that the Owners Group will review and comment on the draft NRC letter to
.. ensees.
wn s Vissing, Project anager Operat ing eactor inch4 Division of Lcen: s n
-c;osures:
c an c losuRres Richard E. Johnson, jS Task Manager Generic Issues 3ranch See next eace Division of Safety Technology
MEETING
SUMMARY
DISTR3UTION Licensee:
S&W,
.estinghouse & CE Owners Groups CCies also sent to those people on service (cc) list for subject ;lant(s).
Docket File NRC POR L POR ORB#4 Rdg Thovak JStolz Project Managers (31)
Licensing Assistants (5)
OELD
- Heltemes, LE00 IE-3 S
Sh ow e Meet in-umay ie-R
- Rraey,
/ACRS-Program Sup:ort *ranch DL Branch Chiefs (4)
JClshinski 3Grimes, CE?
SSchwartz, E?
S5Ram C s, E :.3
??gno, EPL
,.GcnnSOn Ashe Lanninra r zy
- 7.
ars(h
. EisenhUt
. m.
Sroecer
. Lains (:)
7 ois
- 3.. Liaw R. Volmer
.nDenon R. Mattsoni
- 3.
I cker
. /agins Soeis J. l
- 3. L. 3asdekas
- 5. Hanauer 3rown
- 2. 1. Randall L. Shao Abbott J.
Austin R. 3ernere.
. r-stein 0ock
- .ne R.
u
NULEAR REGULATORY COm!SSION
.ncsure C
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- 0.
C.
7o5s5 July 20, 1981 Docket:
(All Operating ?WR's)
MEMORANDUM FOR:
Thomas Novak, Assistant Director for Operating Reactors, DL FROM:
Guy Vissing, Project Manager Operating Reactors Branch 44, DL
SUBJECT:
FORTHCOMING MEETING WITH THE BABCOCK & WILCOX, COMBUSTION ENGINEER, AND WESTINGHOUSE NESS OWNERS GROUPS CONCERNING THE THERMAL SHOCK TO RV ISSUE Time & Date:
According to following schedule B&W Group Westinchouse Grouo CE Grouo July 28, 1981 July 29, 1981 July 30, 1981 1:00-4:15pm 1:00-4:15Epm 1:00-4:15 pm Location:
P-1 8
?-11S P-118 Phillips Building Phillips 3uiiding 3hillics 3uilding
- Bethesda, MD
To discuss the Thermal Shock to Reactor Pressure Vessel issue accorting tot:he
!-tached agenda.
Recues ted articicants:
NRC T. Murley, et. al.
3&W Owners Grouo John 'attimoe, *:
airman
&W Reoresentatives Operating Plant Owners Group Rresentatives 1estinchouse Owners Grouo Rooer: *urgensen, Pna rman W4stinahouse RePresentati Yes Operating Plant Owners G3roup
.ReoreSen atives Corbustion Enaineers Grouo Ken lobr is, ifce Chair-an CE Representatives Oerating PLant Nwners Group RePresentatives Guy~
osig Prj e ct M ae Cperating Reactors 3ranch #4
- ivision of Licensing hone (301) 492-P2136
,7 See next Page