ML20042A152
| ML20042A152 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/16/1982 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| References | |
| TASK-2.B.1, TASK-TM NUDOCS 8203230146 | |
| Download: ML20042A152 (9) | |
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!!r. Henry D. liukill, Vice President I98g and Director - T!!I-l
(A[g[ 6 GPU fluclear Corporation
'f P. O. Box 480 liiddletown, Pennsylvania 17057
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Dear !!r. Hukill:
SUBJECT:
REACTOR C00LAllT SYSTEll VErlTS, (ITEi! II.B.1) - REQUEST FOR ADDITIONAL IfiFORf1ATI0ft lle have conpleted a preliminary review of your submittals regarding Tit! Action Plan Item II.B.1, RCS High Point Vents. The additional infomation identified in the enclosure is mquired to complete our review for your facility.
tie are currently in the process.of reviewing the technical merit of the pmposed operating guidelines for RCS Vent usage. tie recommend that the questions in this area be msolved generically through the Owners Groups. Specific plant procedures will be reviewed against the approved guidelines as needed in the_ future, but not necessarily prior to design approval.
Please supply the requested information within 60 days of the date of this letter.
The reporting and/or recordkeeping requirements contained in this letter are approved under 0:11 clearance #3150-0065 which expires S/31/83.
Sincerely, scRIG15AL StWED EE Jous F. sscE4' John F. Stolz, Chief Operating Reactors Branch #4 Division of Licensing
Enclosure:
P.equest for Additional Inforr.ation cc w/ enclosure:
See next pace E'
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DR ADOCK 03000 OFFICIAL RECORD COPY usa mi-mm
Metropolitan Edison Company cc w/ enclosure (s):
Mr. Marvin I. Lewis Dr. Walter H. Jordan 6504 Bradford Terrace 881 W. Outer Drive Philadelphia, Pennsylvania 19149 Oak Ridge, Tennessee 37830 Walte.r W. Cohen, Consumer Advocate Dr. Linda W. Little Department of Justice 5000 Hermitage Drive Strawberry Square, 14th Floor Raleigh, North Carolina 27612 Harrisburg, Pennsylvania 17127 Ms. Gail P. Bradford Mr. R. J. Toole Anti-Nuclear Group Representing Manager, TMI-1 York Metropolitan Edison Company 245 W. Philadelphia Street P. O. Box 480 York, Pennsylvania 17404 Middletown, Pennsylvania 17057 John Levin, Esq.
Pennsylvania Public Utilities Com.
John E. Minnich, Chairman Box 3265 Dauphin Co. Board of Comissioners Harrisburg, Pennsylvania 17120 Dauphin County Courthouse Front and Market Streets Jordan D. Cunningham, Esq.
Harrisburg, Per.nsylvania 17101 Fox, Farr and Cunningham 2320 North 2nd Street
- Atomic Safety and Licensing Appeal Board Harrisburg, Pennsylvania 17110 U.S. Nuclear Regulatory Commission Washington, D. C.
20555 Ms. Louise Bradford TMIA
- Atomic Safety and Licensing Board Panel 1011 Green Street U.S. Nuclear Regulatory Commission Harrisburg, Pennsylvania 17102 Washington, D. C.
20555 Ms. Marjorie M. Aamodt
- Docketing and Service Section R.D. #5 U.S. Nuclear Regulatory Comission Coatesville, Pennsylvania 19320 Washington, D. C.
20555 Mr. Richard Roberts Robert Q. Pollard The Patriot 609 Montpelier Street 812 Harket Street Baltimore, Maryland 21218 Harrisburg, Pennsylvania 17105 Chauncey Kepford Earl B. Hoffman Judith H. Johnsrud Dauphin County Comissioner Environmental Coalition on Nuclear Power Dauphin' County Courthouse 433 Orlando Avenue Front and Market Streets State College, Pennsylvania 16801 Harrisburg, Pennsylvania 17101 Judge Gary J. Edles, Chairman Atomic Safety and Licensing Appeal Board Harmon & Weiss U.S. Nuclear Regulatory Commission 1725 I Street, N.W.
Washington, D.C.
20555 Suite 506 Washington, D. C.
20006 J. B. Lieberman, Esq.
Mr. Steven C. Sholly Berlock. Israel & Liberman Ifnion of Concerned Scientists 26 Broadway 1725 I Street, N. W., Suite 601 New York, NY 10004 Washington, DC 20006
Metropolitan Edison Company General Counsel Federal Emergency Management Agency Mr. Thomas Gerusky ATTN:
Docket Clerk Bureau of Radiation Protection 1725 I Street, NW Department of Environmental Resources Washington, DC 20472 P. O. Box 2063 Harrisburg, Pennsylvania 17120 Karin W. Carter, Esq.
505 Executive House P. O. Box 2357 Professor Gary L. Milhollin Harrisburg, Pennsylvania 17120 1815 Jefferson Street Madison, Wisconsin 53711 York College of Pennsylvania Country Club Road York, Pennsylvania 17405 G. F. Trowbridge, Esq.
Dauphin County Office Emergency Shaw, Pittman, Potts & Trowbridge Preparedness 1800 M Street, N.W.
Court House, Room 7 Washington, D. C.
20036 Front & Market Streets Harrisburg, Pennsylvania 17101 Mr. E. G. Wallace Licensing Manager Department of Environmental Resources GPU Service Corporation ATTH: Director, Office of Radiological 100 Interpace Parkway Health Parsippany, New Jersey 07054 P. O. Box 2063 Harrisburg, Pennsylvania 17105 William S. Jordan, III, Esq.
Ms. Lennie Prough Harmon & Weiss U. S. H. R. C. - Till Site,
1725 I Street, NY, Suite 506 P. O. Box 311 Washington, DC 20006 Middletown, Pennsylvania 17057 Ms. Virginia Southard, Chairman Citizens for a Safe Environment 264 Walton Street Lemoyne, Pennsylvania 17043 Mr. Robert B. Borsum Babcock & Wilcox Government Publications Section Nuclear Power Generation Division State Library of Pennsylvania Suite 220, 7910 Woodmont Avenue Box 1601 (Education Building)
Bethesda, Maryland 20814 Harrisburg, Pennsylvania 17126
- Ivan W. Smith, Esq.
Mr. David D. Maxwell, Chairman Atomic Safety & Licensing Board Panel Board of Supervisors U.S. Nuclear Regulatory Commission Londonderry Township Washington, D. C.
20555 RFD#1 - Geyers Church Raod Middletown, Pennsylvania 17057 Mr. C. W. Smyth Supervisor of Licensing THI-l Metropolitan Edison Company-Regional Radiation Representative P. O. Box 480
' EPA Reaion III Middletown, Pennsylvania 17057 Curtis~ Building (Sixth ~ Floor) 6th and Walnut Streets Philadelphia, Pennsylvania 19106 Mr. Donald R. Haverkamp Governor's Office of State Planning SeniorResidentInspector(TMI-1) and Development U.S.N.R.C.
ATTN: Coordinator, Pennsylvania P. O. Box 311 Stat.e Clearinghouse Middl etown,' Pennsyl vania 17057 P. O. Box 1323 Harrisburg, Pennsylvania 17120
Metropolitan Edis:n Company Judge John H. Buck Atomic Safety and Licensing Appeal Board Panel U.S. Nuclear Regulatory Corsnission Washington, D.C.
20555 Judge Christine N. Kohl Atomic Safety and Licensing Appeal Board Panel U.S. Nuclear Regulatnry Commission Washington, D.C.
20555 Judge Reginald L. Gotchy Atomic Safety and Licensing Appeal Board U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Mr. Ronald C. Haynes, Regional Administrator U. S. N. R. C., Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 Board of Directors P.A.N.E.
P. O. Box 268 Middletown, Pennsylvania 17057 l
Enclosure REQUEST FOR ADDITIONAL INFORMATION FOR THREE MILE ISLAND I 1.
In addition to the Bobcock & Wilcox " Operating Guidelines for High Point Vents Dering Small Break Transients" referenced in your response to NUREG-0737 Item 11.8.1, and the information provided in your " Division 11 System Design Description" (SDD-222A Rev.0), provide additional information regarding the following:
'o.
Criteria or pertinent information concerning a decision to terminate venting based on containment hydrogen concentration limits or pressurizer level limits.
b.
Methodology describing the determination of the location and size of a noncondensible gas bubble in the reactor coolont system (reference NUREG-0737 Item II.B.I Position (2) and Clarification A.(2)).
Operating guidelines for venting of the pressurizer in order to maintain c.
system pressure and volume control (reference NUREG-0737 f tem 11.B.1
~
Clarification C.(3)).
2.
Section 7.4.3.1.1 of your " Division 11 System Design Description" (SDD-222A Rev. 0) cnd Section 3.1 of the Bcbcock and Wilcox " Operating Guidelines for High Point Vents During Small Break Transients" referenced in your submittal both state that the operator will open the hot leg high point vents when the refill phase of the accident commences. In. practice, the operator has no means to determine whether steam or saturated water is present in the hot legs, and will probcbly not notice o difference between natural circul0 tion and steam condensing heat transfer modes.
A transifion from one heat transfer mode to another may be obscured by temporary
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operation of the pressure vessel internal vent volves between the cold and hot legs. Discuss in detail how timely venting ccnhe assured and present the necessary diagnostic and operational steps in explicit guideline form.
3.
Section 3.3 of'the Babcock and Wilcox " Operating Guide!ines for High Point Vents
^
During Small Break Transients" referenced in your submittel, prescribes operator
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actions to depressurize the reactor coolant, rystem with a bubble in the reactor -
vessel head. Although we assume normally this g'uidance applies only to plants without reactor vessel head vents, it may also apply to Three Mile Island I for the following two reasons. First, the reactor vesse} head vent at Three Mile Island I is not redundant and thus might be disabled by a single failure. Second, since your reactor vessel head vent is not at the highest point of the vessel, a small noncondensible gas bubble could remain even af ter venting the reactor vessel head. Therefore, since the prescribed operator actions to depressurize the reactor coolant system with a bubble in the reactor vessel head could apply to Three Mile Island I, we require that you respond to the following NRC concern.
I Section 3.3 of the Babcock and Wi!ccx guidelines states that once natural circulaticn is established and temperatures in the hot and cold legs are between 50 F and 100 F subcooled, the operator is.to depressurize the plant with the 0
press'urizer high point vent or PORV at a rate not greater than indicated by Curve I 4
of Figure 2.
This maximum allowable depressurizailon rate is based on assuring that the rate of expanding gas from the vessel head into the hot legs is less than the relieving capability of the hot leg high point. vents in urder to preclude a net accumulation of gas at the top of the hot legs ' and interruption of natural circulation. The staff disagrees with this method of depressurization with a bubble s
in the reactor vessel head for the following reason:
The maximum o!!owable depressurization rate provided by Curve I of Figure 2 of the Babcock and Wilcox (B&W) guidelines i
appears to be based or computer analyses.
B&W and their 3
customers have yet to. satisfactorily demonstrate to the staff the adequacy of their analysis models to properly predict the transport of steameand other gases in the vessel and primary coolant loops under transient and accident conditions. 'r& ding post-LOCA.
As such, we believe the uncertab m
'n the depressurization rates shown in Figure 2 to b, e s im ed,and the consequences of incorrect depressurization -,gnn.2 #.
We, therefo e, request that you identify a me had of depressurizing the primary system with the assumption of a bubble in the reactor vessel head which does not rely en computer calculated curves and does not involve a risk of interruptice of natural circulation.
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4.
During conditions of inadequate core cooling, the operator is instructed to open the high point vents.
Another instruction is to start the reactor coolant pumps (RCPs). If the pumps are started, can a slug of water impact the reactor vessel head or hot leg piping at the high point vent location? If so, is the vent system designed to withstand the dynamic loads associated with these water slugs? If not, what precautionary measures are provided or will be provided to preclude pump -
start with the vents open?
5.
Recently, a number of plants with B&W-designed NSSS's have experienced bubble formation in the hot leg piping while in the shutdown cooling mode. This has been caused by the flashing of stagnant hot water in the hot legs during depressurizing operations by the operator (the hot water was possibly due to outsurges from the pressurizer).
What instructions are provided to the operator regarding the use of the vents to remove trapped steam under these conditions? In particular, should the vents be used or not? Consider that the containment may not be isolated and personnel may be in containment. If vent operation under these conditions must be avoided, what provisions have been made to preclude vent operation?
/.
On page 18 of the Division 11 System Design Description, it states that when the RCPs are not available following a small break LOCA for removing trapped gases from the reactor coolant system high points, the hot leg vents can be utilized.
Moreover, the first sentence in section 7.4.3.1.1 (page 18) states that operator action will be required to open the vents during small break transients. It is our l
l tnderstanding that neither the RCPs nor the high point vents are considered to be l
part of the engineered safety features (ESFs) and are not required to be operable following a LOCA. Previous ECCS analyses submitted on license applications for I
plants with B&W NSSS's were not performed beyond the start of primary system inventory recovery and it was assumed that single phase natural circulation would be reestablished without the aid of either the RDPs or the high point vents.
l i
l-Please state whether or not operation of the RCPs and/or the high point vents are necessary in order to reestablish single phase natural circulation following a small break LOCA. If they are required, justify why they are not considered part of the l
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i engineered safety features, and required to meet the design requirements of ESFs.
If they are not required, provide the supporting analyses for small break LOCAs which demonstrate that single phase natural circulation will be reestablished-following recovery from o small break LOCA. Discuss how steam tropped in the reactor coolant system high points (vessel head and hot leg " candy cones") will be condensed or removed and not inhibit natural circulation or long-term cooling of the core, per the requirements of 10CFR50.46(b)(5).
When considering the need of the high point vents take into account also the possibility of on early break isolation which takes place during the period between interruption of natural circulation and stort of steam condensing heat transfer.
l 7.
The fo!!owing items apply to the portions of the reactor coolant system (RCS) vent l
system that form o part of the reactor coolant pressure boundary, up to and l
including the second normally closed volve (reference NUREG-0737 Item II.B.I Cicrification A.(7)):
]
Verify that the matericts of construction will be fabricated and tested in c.
accordance with SRP Section 5.2.3, " Reactor Coolont Pressure Boundary Materials."
b.
Verify that the Nuclear Class N-l and N-2 designations of the piping, valves, components, and supports are equivalent to Safety Classes I and 2, respectively (i.e., ASME Boiler crsd Pressure Vessel Code, Section ill, Classes I and 2).
8.
Section 7.l.5 of the Division 11 System Design Description for RCS vents states that the physical arrangement of the RCS vents is shown on GPUSC drawing number IE-222-22-001, Sheets I and 2, yet this drawing was not included in the submittal.
Provide this drawing and any others necessary to demonstrate that the RCS vent i
paths to the containment atmosphere discharge into areas in which any nearby j
I structures, systems, and components esserdial to safe reactor shutdown or mitigation of the consequences of a design basis accident are capable of i
withstanding the effects of the anticipated mixtures of steam, liquid, and noncondensibles discharging from the vent system.
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l 9.
Verify that motor-operated valve RC-V28 is provided with positive position indication in the control room and is powered from on emergency bus (reference NUREG-0737 Item !!.B.I Clarifications A.(5) and (8)).
10.
Verify that all displays (including atorms) and controls, added to the control room as a result of the TMI Action Plan requirement for reactor coolant system vents, have been or will be considered in the human focotrs analysis required by NUREG-0737 Item 1.D.1, " Control-Room Design Reviews."
l1.
Verify that the following RCS vent system failures have been analyzed and found not to prevent the essential operation of safety-related systems required for safe reactor shutdown or mitigation of the consequences of a design basis accident:
Seismic failure of RCS vent system components that are not designed to a.
. ithstand the safe shutdown earthquake.
w b.
Pestulated missiles generated by failure of RCS vent system components.
Dynamic effects associated with the postulated rupture of hot leg high point c.
vent piping greater than one-inch nominal size.
d.
Fluid sprays from RCS vent system component failures. Sprays from normally unpressurized portions of the RCS vent system that are Seismic Category I and Safety Class I, 2, or 3 and have instrumentation for detection of leakage from upstream isolation valves need not be considered.
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