ML20027E627
| ML20027E627 | |
| Person / Time | |
|---|---|
| Site: | Pennsylvania State University, 07000113 |
| Issue date: | 10/18/1982 |
| From: | Cunningham R PENNSYLVANIA STATE UNIV., UNIVERSITY PARK, PA |
| To: | Thomas C Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20027E628 | List: |
| References | |
| NUDOCS 8211150551 | |
| Download: ML20027E627 (17) | |
Text
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THE PENNSYLVANI A STATE UNIVERSITY 207 OLD MAIN BUILDING UNIVERSITY PARK. PENNSYLVANIA 16802 Vice President fc Area Code 814 Rwarch and Graduate Studie, 865-6332 October 18, 1982 Chief, Cecil Thomas Standardization and Special Projects Branch Division of Licensing Nuclear Regulatory Commission Washington, D.C.
20555 Subj ect: Request for Change in Technical Specifications Docket No.:
50-5 NRC License:
R-2
Dear Sir:
An amendment to The Pennsylvania State University Breazeale Nuclear Reactor's (PSBR) technical specifications is requested to permit using non-TRIGA fuel elements, containing 6.95% enriched UO2 fuel pellets, in subcritical arrays with the TRIGA core and control system. The UO 2 pellets will be obtained by disassembling several Pathfinder fuel assemblies, and the non-TRIGA fuel elements will be constructed to have dimensions similar to TRIGA fuel elements. The subcritical experiments using the non-TRIGA fuel elements are to be used as part of a Ph.D. research thesis to develop techniques to determine the fuel and poison distribution in a damaged-reactor. The period for which the amendment is requested is five years; the experiments are planned to be complete within that time period.
All experiments performed with the non-TRIGA fuel elements in the TRIGA reactor core shall meet the following two additional conditions:
(1) the core shall have k gg 1 0.99 with all control rods at e
their full out position, i.e., out of the core.
(2) the reactor power switch shall not be turned above the 1 kw range; this provides a scram to occur at 1.1 kw.
The present requitement on close packed arrays of the TRIGA fuel elements is to be precluded from these experiments. It will be necessary to have flexibility to position the non-TRIGA type fuel elements in different arrays wherein several fuel element positions are lef t vacant.
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Pagn 2 Therefore, in-paragraph 1,'Section E., Reactor Core, of the PSBR technical-specifications which now reads as; 1.
The core shall be an sssembly of either 8.5 wt%. stainless steel clad or a mixture o' l.5 wt% and 12 wt% stainless steel clad TRICA fuel-moderator alements placed in water with a 1.7 inch centerline grid spacing. The fuel and fueled follower control rods shall be arranged in a close packed array except for (1) single positions, (2) positions' greater than five inches from the center of the' core where flux peaking and corresponding.
power densities produce fuel temperatures less than in the B-ring..
shall be replaced with; 1.
When the keff of the core is greater than 0.99 with all control rods at their upper limit, the core shall be an assembly-of either 8.5 wt%
stainless steel clad or a mixture of 8.5 wt% and 12 wt% stainless steel clad TRIGA fuel-moderator elements placed in water with a 1.7.
inch centerline grid spacing. The fuel and fueled follower control rods shall be arranged in a close packed array except for (1) single position, (2) positions greater.than five inches from the center of the core where flux peaking and corresponding power densities produce fuel temperatures less than in the B-ring.
When the k gg of the core is less than cr equal to 0.99, the fuel may e
or may not be arranged in a close packed array and Pathfinder TRIGA (PATR) fuel elements may be used. The determining factor is that the array must have-keff ;E 0.99, with all control rods at their upper limit. The source and detector shall be arranged such that the keff of the suberitical assembly shall_always be measured and
-monitored to assure co:# 11ance with keff ;E 0.99.
The attached report, Attachment 1, describes the design and construction of the non-TRICA fuel elements to be used in these experiments. In addition, the method to be used in transporting and-handling the Pathfinder fuel assemblies during and af ter the experiments are completed is also presented.
Each Pathfinder fuel
[
assembly contains 153.32 gms of U-235; hence, when the five or more fuel assemblies are stored in the facility they will exceed 700 gms
.U-235.
Section 70.24, " Criticality Accident Requirements," of' 10 CFR Part 70, " Domestic Licensing of Special Nuclear Material,"
l
' requires that licensees who possess ~special nuclear materials (SNM) i in a quantity exceeding 700 gms of contained U-235, shall maintain in each area in which such licensed SNM is stored a monitoring system meeting specified requirements. The storage of the Pathfinder fuel i
elements is presently exempt from this requirement.
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The Pathfinder fuel elements are presently licensed under Special L
Nuclear Material License number SNM-95 to be possessed and stored but not used in accordance with the statements and conditions:in the application dsted 29 June 1962, and supplements dated 10 July 1968 and 3 July 1969. The elements are now.being stored in a security vault-type room located in the Academic Projects Building, approximately l
100 meters from the PSBR facility. The Pathfinder fuel elements are stored in racks, each shelf having a maximum of 11 fuel assemblies.
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l Pega 3 This program will use no more than 15 Pathfinder fuel assemblies, and they will be stored in two specially designed transportation cases separated by at least one foot. The specially designed transportation cases will-hold no more than 8 Pathfinder fuel assemblies each, and thus their criticality when flooded will be less than that of the fuel assemblies in the racks where they are now stored. We are, therefore, requesting exemption from Section 70.24 of 10 CFR Part 70.
The Penn State Unviersity Reactor Safeguards Committee will review and approve these experiments before they are performed.
A separate request for ammendment is being made to amend the special nuclear license, SNM-95, to allow use of'the fuel as described herein. A copy of this request is included as Attachment 2.
If you have any questions regarding this request, you may address your questions to this office or to Professor S. H. Levine, telephone (814) 865-3110.
Sine rcly, Richard G. Cunningham Vice President for Research and Graduate Studies enc. Attachment 1 Attachtent 2 cc:
E. H. Klevans S. H. Levine I. B. McMaster W. F. Witzig Reactor File 4
1.
EXPERIMENT TO DETERMINE THE FUEL AND POISON DISTRIBUTION IN A SIMULATED DAMAGED CORE An experimental program is to be performed at the Penn State University Breazeale Reactor (PSBR) using the TRICA core and non-TRIGA fuel elements to develop techniques to determine the fuel and poison distribution in a simulated damaged core. The damaged core will be simulated by replacing TRIGA fuel elements with non-TRIGA fuel elements in a subcritical core. The non-TRICA fuel elements are to be constructed with UO fu 1 pellets taken from Pathfinder 2
fuel assemblies now stored at Penn State.
Penn State has custody of 417 Pathfinder fuel elements. Figure 1 shows a schematic of a Pathfinder fuel element. The fuel in the 417 Pathfinder fuel assemblies are pellets of UO having a diameter of 2
235 0.207 inches enriched to 6.95% in U.
Additional information regarding the Pathfinder fuel assembly is given in Table 1.
A maximum of 15 of these Pathfinder fuel elements will be dismantled and the UO2 pellets used to construct Pathfinder TRICA (PATR) fuel elements as shown schematically in Figure 2.
A PATR fuel element will be constructed of several small aluminum tubes,10.25" 0.D., partially filled with UO2 pellets; some will contain both poison pellets and fuel. Metal spacers will be used inside the tubes to hold the fuel and poison in position.
Each aluminum tube, filled with fuel and spacers and called a fuel pin, will be arc-welded at the top and bottom and checked to be leak tight.
The several fuel pins comprising one PATR fuel element will be held together by special aluminum fittings placed at the top and bottom of 1.
Gui, A.
A.,
Levine, S. H.
A UO2 Fuel Element Design for Use in the Penn State Breazeale Reactor (PSBR), ANS Trans., Vol. 35, November 1980.
1
o 2
0.805" a
- Envelope Diameter O
U 2,
-5 5 5
\\
b U
Inco11oy 800 Cladding on Fuel Rod 5 \\
5
.c 5
5
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U T i 5
'S 5 h bh hf "d
e; "
"5 hV e
?.
a UO Fuel Pellets 35 U
2 3
3 3
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t 5 5 5
u y
Outer Diameter w
Q 0.875" a
Fig.
1.
Pathfinder Fuel Element
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TAlsl.li i l'athfiniter 1:ncl lilement Specifientions filement Configio at ion 7-rod Cluster overall element length M2.55 in.
linvelope iliameter 0.805 in.
Nominal weight 9.0 lb.
l'ue i Sint cred 110 Peliet 3
IJO, en richment 6.95 w/o 11-J35 f.o.5 ding per element J. 206 _ Kgli 1102 pellet diameter U.207 1 0.0005 in.
UO2 inellet length U. 207 - 0.111 in.
Active fuel length 72.0 1 0.125 in.
Cladding of 1:nel and Poison Itods Irce Standing Tube Material incoloy 800, mill annealed Ont side iliameter 0.217 1 0.001 in.
Insiile aliamet er 0.211 ! 0.001' in.
Wall thickness 0.018 in.
Poison lloron-Stainless Steel Wire l'oison loading per element 0.978 g natural boron Poison wire iliameter U.105 in.
Poi son sjiacer Sintered Al;03 pellets Spacing Arrangement Spi ral Wi re, 3 per Fuel Itod Wire diameter 0.012 in.
Spiral pitch h in.
Wire material Incoloy 800, mill annealed I i ssion Gas I'lentun f.ength 3 in.
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1 t
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17 Pathfinder Fuel 1(ods d
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(Fuel Length = 15")
i 28.37"
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1 1
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2.
PATR Fuel Element 4
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w em--
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of the fuel pins. This special fitting will act as a grid spacer for the fuel pins. The diameter of the special fittings will be equal-to the diameter of the TRIGA fuel. The top fitting will be machined to allow the fuel to be moved with the standard TRIGA fuel element tool,,and the bottom fixture will position the fuel element in the core bottom.
The outer rim of fuel pins will be spot welded to the two fixtures to provide a strong and firm structure. The overall size of the PATR fuel elements will be similar to that of the TRIGA fuel elements. These fuel elements will be judiciously placed in the TRIGA core to mock up a damaged core and provide a basis for performing experiments to verify the analytical-experimental techniques proposed in the program.
The experimental measurements will begin with no PATR fuel elements in the core. A critical or slightly critical reactor (less than 1% Ak/k) will be used to calibrate TRIGA fuel element worths and control rod worths.( } The k or k of subcritical cores will be carefully gg determined for cores having k between 0.97 and 0.995.
Once these measurements are checked and measured k verified, experiments with the PATR fuel elements will begin.
All experiments performed with the PATR fuel elements in the TRIGA i
core will have a k < 0.99 when all control rods are fully withdrawn
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from the core.
In addition the reactor power switch shall not be turned above the 1 kw position. The scram shall occu,r anytime the reading on l
the linear scale is between 108.5 to 110% of the 1 kw range. The core l
configurations will be designed to approximate either axial or half-i I
2 TRIGA Subcrit ical Experiments in Support of the km Meter. Ocampo, H.,
Levine, S.
H., and Schultz, M. A.
ANS Trans., Vol. 35, November 1980.
l l
6 core symmetry to reduce computation costs. The core top central region for some configurations will contain large water holes to simulate the damaged TMI-2 core configuration. Ilowever, the source detector positions will always have fuel between them to assure accurate monitoring of the core neutron source multiplication characteristics.
The k (keff) of the core will be measured, as the core configurations are changed when k is less that 1, by monitoring the count rate produced by a Cf-252 neutron source (approximately 15 p gms Cf-252) in the core.
The measurements will be carefully followed by performing 2-D computer analyses of the measurements. The basic formula used here is, CR (1 - k )
CR (1 - k )
where CR
= count rate of new configuration 7
CR
= count rate of calibrated configuration g
k, k
of calibrated core
=
gg k
k of new configuration.
=
g gg Rearranging Eq. (1) gives CR 1
1 - (CR )(1 - k )
(2) k
=
o y
which is the expression to be used to determine k af ter each change.
Care will be taken to account for any relative change in source and/or fuci position and more than one detector will be used to verify the k measurement.
When the PATR fuel element contains 17 fuel rods with UO filling 2
will have a k,s the 15" core height, it
= 1.65.
This is less than the k,
of the 12 w/o TRIGA fuel elements which have k, = 1.8 and greater than
i 7
e the k, of the 8.5 w/o TRICA fuel elements. The latter fuel elements have a k,
1.45.
Replacing the 12 w/o TRIGA clements with PATR fuel elements will reduce the k of the core. The first measurements performed will be of this type to assure calculations agree with the experiment when k is reduced by substituting the PATR fuel element.
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8 II.
PATHFINDER FUEL TRANSPORTATION PROCEDURE A.
Introduction The Pathfinder fuel assemblies are presently stored in a security vault type room located in the basement of the Academic Projects Building (APB).
The APB is situated about 100 yards west of the Nuclear Reactor Facility.
Before the fuel assemblies are dismantled, the fuel must be transported from the storage vault across a lawn area and into the Breazeale Reactor Facility (PSBR).
The fuel transportation procedure presented herein insures the physical integrity and safe handling of the fuel assemblies while they are being prepared for transportation in the APB, transported to and received in the PSBR. The procedure will be approved by the Reactor Safeguards Committee before fuel is moved. The procedure ensures that the fuel assemblies are carefully handled and that due regard is made for the safety of personnel and the public.
B.
Definitions 1.
Transportation - refers to the physical movement, by hand or other means, of the Pathfinder fuel element from the APB to the PSBR along the designated transportation route, which is about 100 yards long.
2.
Handling - refers to the physical grasping and manipulation of the individual fuel elements or group of fuel elements.
C.
General Guidelines 1.
One person will be designated "supervisur" of the handling and transportation of the fuel elements. His duty will be the overall i
9 supervision of handling and transportation of the fuel elements during the transportation procedure.
2.
A fuel element handling and transportation log book will be maintained. This log book will detail the handling of the fuel assemblies during the transportation of the fuel.
3.
The names of the supervisor and other crew members will be recorded in the log book.
4.
The University Health Physics Department and Police Services Department will be notified of the intent to move nuclear fuel prior to the transportation of the fuel elements.
5.
All personnel involved in the handling and transportation of the fuel elements must be approved by the Director of the Breazeale Nuclear Reactor Facility or his representative.
6.
Gloves shall be worn by all individuals transporting the fuel elements.
4 7.
Transportation of the fuel elements will take place during the daylight hours.
8.
The fuel elements will be transported in transportation cases, 2" thick x 12" wide x 84" long, specifically designed for this purpose, and schematically shown in Figures 3 and 4.
9.
A transportation case will be carried by at least,two people and its gross weight will not exceed 100 pounds.
10.
No more than 15 Pathfinder fuel elements will be transferred to the PS3R.
f 11.
When both transportation cases are stored with fuel in the reactor bay, they will be placed a minimum of 12" apart.
e 10
< --- - 1 2 --
llandle (bolted)
)~-
Weld Al Angle 1.5"x1.5" x 1/8" Al Rectangular 1/8"x1" (Welded to the Al Angle) 84" l's" x l'3" x 1/8" Aluminum Angle Bar 1/8" x 1" Aluminum Rectangular Bar N
k
' N\\
- (
f llandle k
_ _ _y )-
V
/~~"
Figure 3.
Fuel Element Transportation Cask
11 Hinge --+01 U L.@
Latch III Il II G O
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{} 3
[ I3 0T If 1Tl Figure 4,.
Transportation Cask Cover
..a.
o 12 III. CONSTRUCTION AND HANDLING PROCEDURE FOR THE PATR FUEL ELFliENTS The procedure to be used to dismantle the Pathfinder fuel element and construct new PATR fuel elements will be as follows:
1.
The Pathfinder fuel elements will be removed from the storage room and transported to the reactor facility as described in section II, " Pathfinder Fuel Transportation Procedure".
2.
The Pathfinder fuel assemblics will be disassembled in the machine shop of the PSBR (no flame cutters will be used).
Special care will be taken to assure the UO fu 1 pellets do 2
not contaminate the area and to maintain strict cleanliness during the construction of the PATR fuel elements.
3.
The fuel pellets will be counted to verify the inventory of each fuel element. A few pellets will be weighed to verify the UO c ntent.
Each Pathfinder fuel element contains 2.206 2
kg of uranium of which 153.32 gm is U-235.
4.
The PATR fuel elements will be manufactured in the machine shop at the PSBR, and careful supervision will be maintained over the fuel inventory at all times. The transportation log book will also be used to maintain inventory accountability.
5.
No more than two Pathfinder fuel assemblies will be dismantled-at one time in the machine shop. Thus the unclad UO p 11ets 2
will always be less than 350 gms of U-235.
6.
At the end of each day the fuel will be removed f rom the machine shop to one of the security areas in the reactor building where it will be secured over night. The security areas in the reactor building are protected during non-working' hours with intrusion alarms.
- See II. B. for definition L
13 7.
Once the PATR fuel elements have been constructed and checked for leaks, they will be stored in the reactor pool with the other TRICA fuel elements.
8.
Each time a PATR fuel element is removed from the storage rack into the core or vice a versa, it will be checked visually to be sure that it is a PATR fuel element. This can be easily done because the water in the TRICA core is clear,'and the design of the PATR fuel element is greatly different from that of the standard TRICA fuel element.
9.
The PSBR log book carefully maintains a correct log of the TRICA fuel elements in the core and storage rack and their positions at all times.
The PATR fuel elements will also be carefully logged in the same way.
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. - + -.. - - -
e 14 IV.
STORAGE OF USED PATHFINDER FUEL AT COMP 1.ETION OF F.XPERIMENTS The unused portion of the d'
<rembled Pathfinder fuel assemblies will be returned to the security vault type room in the APB with the other fuel assemblies when they are no-longer needed. The PATR fuel elements will also be transported to the APB and stored in the security vault. The boron wires from the dismantled Pathfinder fuel assemblies will be positioned between the PATR fuel elements to maintain 'an adequate safety margin as before. The same transportation rules used for transporting the Pathfinder fuel assemblies will apply to transferring the PATR fuel elements.
Any unused UO fuel p 11ets will be placed in the incoloy tubes 2
of the dismantled Pathfinder fuel assemblies, marked for UO c ntent, 2
and sealed with plastic wrapping and tape and a security seal. All rules and regulations regarding the SNM-95 license and the R-2 license will be followed. The PATR fuel elements will be designed to miaimize 1
the number of free UO2 pellets remaining after constructing the last PATR fuel element.
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