ML071700633

Purdue University - Conversion of PUR-1 from HEU to Leu, Follow-up on RAI Responses

ML071700633
Person / Time
Site:	Purdue University
Issue date:	06/18/2007
From:	Joel Jenkins Purdue University
To:	Alexander Adams NRC/NRR/ADRO/DPR/RTRBA
References
Download: ML071700633 (7)

Text

PURDUE U N .] V E R S I 'T Y SCHOOL OF NUCLEAR ENGINEERING 18 June 2007 Mr. Alexander Adams, Senior Project Manager Research and Test Reactors Branch A US Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, MD, 20852-2738

SUBJECT:

Docket No. 050-0182, Facility License R-87; Conversion of PUR-1 from HEU to LEU, Follow-up on RAI responses.

Dear Mr. Adams:

As per our phone conversations last week, and the conversation with Mr. William Schuster of your office this morning, we would like to make the following clarifications to the documentation for the conversion of PUR-1 from HEU to LEU:

1. The procedure included in the conversion proposal was for information purposes, as recommended by NUREG 1537, and was presented in draft form. All procedures used by PUR-1 staff will go through the standard composition and approval process used at Purdue. Therefore, we request that no procedures be included in the order to convert.

2. Technical Specification 5.2.2 should read as follows: "A standard fuel assembly shall consist of up to 14 fuel plates containing a maximum of 180 grams of U-235."

3. Technical Specification 5.2.3 should read as follows: "A control fuel assembly shall consist of up to 8 fuel plates containing a maximum of 103 grams of U-235."

4. The basis for Technical Specification 2.2, Limiting Safety System Setting, is still valid. We request an update of the value in the second paragraph of the basis from 96.7 to 94.2 kW, as explained in the response to Question 27 in the RAI.

As requested, replacement pages for the proposed Technical Specifications changes are included with this letter. Should you have any questions, or require 02-

" School of Nuclear Engineering Nuclear Engineering Building

• 400 Central Drive - West Lafayette, IN 47907-2017 (765) 494-5739

• Fax: (765) 494-9570 ° https://engineering.purdue.edu/NE

further information, please contact me via e-mail at jere@purdue.edu, or telephone at 765.496.3573.

I declare under penalty of perjury that the foregoing is true to the best of my knowledge, executed on this day of 18 June 2007.

• rl or of Ra tion Laboratories

Enclosures:

As stated Cc: Mr. Dan Hughes, USNRC Mr. William Schuster, USNRC Letter to Mr. Al Adams, USNRC Pg 2 of 2 18 June 2007

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2. SAFETY LIMIT AND LIMITING SAFETY SYSTEM SETTING 2.1 Safety Limit Safety limits for nuclear reactors are limits upon important process variables that are necessary to reasonable protect the integrity of certain of the physical barriers that guard against the uncontrolled release of radioactivity. The principal physical barrier is the fuel cladding.

Applicability - This specification applies to the temperature of the reactor fuel and cladding under any condition of operation.

Objective - The objective is to ensure fuel cladding integrity.

Specification - The fuel and cladding temperatures shall not exceed 530'C (986°F).

Basis - In the Purdue University Reactor, the first and principal barrier protecting against release of radioactivity is the cladding of the fuel plates. The 6061 aluminum alloy cladding of the LEU fuel plates has an incipient melting temperature of 582°C. However, measurements (NUREG-1313) on irradiated fuel plates have shown that fission products are first released near the blister temperature (-550'C) of the cladding. To ensure that the blister temperature is never reached, NUREG 1537 concludes that 530'C is an acceptable fuel and cladding temperature limit not to be exceeded under any condition of operation.

2.2 Limiting Safety System Setting Applicability - This specification applies to the reactor power level safety system setting for steady state operation.

Objective - The objective is to assure that the safety limit is not exceeded.

Specification - The measured value of the power level scram shall be no higher than 1.2 kW.

Amendment No. 11

8 Basis - The LSSS has been chosen to assure that the automatic reactor protective system will be actuated in such a manner as to prevent the safety limit from being exceeded during the most severe expected abnormal condition.

The function of the LSSS is to prevent the temperature of the reactor fuel and cladding from reaching the safety limit under any condition of operation. During steady-state operation, a power level of 94.2 kW is required to initiate the onset of nucleate boiling. This is far higher than the maximum power of 1.8 kW, which allows for 50% instrument uncertainties in measuring power level.

For the transients that were analyzed, the temperature of the fuel and cladding reach maximum temperatures of 31VC, assuming reactor trip at 1.8 kW after failure of the first trip. This temperature is far below the safety limit of 530 0 C.

Amendment No. 11

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b. The conductivity of the primary coolant shall be recorded weekly.

c. The reactor pool water will be at or above the height of the skimmer trough whenever the reactor is operated.

d. Monthly samples of the primary coolant shall be taken to be analyzed for gross alpha and beta activity.

Bases - Weekly surveillance of pool water quality provides assurance that pH and conductivity changes will be detected before significant corrosive damage could occur.

When the reactor pool water is at the skimmer trough level, adequate shielding of more than 13 feet of water is assured.

Analysis of the reactor water for gross alpha and beta activity assures against undetected leaking fuel assemblies.

4.4 Containment Applicability - This specification applies to the surveillance requirements for maintaining the integrity of the reactor room and fuel clad.

Objective - The objective is to assure that the integrity of the reactor room and the fuel clad is maintained, by specifying average surveillance intervals.

Specification -

a. The negative pressure of the reactor room will be recorded weekly.

b. Operation of the inlet and outlet dampers shall be checked semiannually, with no interval to exceed 7 1/2 months.

c. Operation of the air conditioner shall be checked semiannually, with no interval to exceed 7 1/2 months.

d. Representative fuel assemblies shall be inspected annually, with no interval to exceed 15 months.

Bases - Specification a, b, and c check the integrity of the reactor room, and d the integrity of the fuel clad. Based upon past experience these intervals have Amendment No. 11

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5. DESIGN FEATURES 5.1 Site Description 5.1.1 The reactor is located on the ground floor of the Duncan Annex of the Electrical Engineering Building, Purdue University, West Lafayette, Indiana.

5.1.2 The School of Nuclear Engineering controls approximately 5000 square feet.

5.1.3 Access to this area is restricted except when classes are held here.

5.1.4 The reactor room remains locked at all times except for the entry or exit of authorized personnel.

5.1.5 The PUR-1 is housed in a closed room designed to restrict leakage.

5.1.6 The minimum free volume of the reactor room shall be 15,000 cubic feet.

5.1.7 The ventilation system is designed to exhaust air or other gases from the reactor room through an exhaust vent at a minimum of 50 feet above the ground.

5.1.8 Openings into the reactor room consist of the following:

a. Three personnel doors

b. Two locked transformer vault doors

c. Air intake

d. Air exhaust

e. Sewer vent 5.2 Fuel Assemblies 5.2.1 The fuel assemblies shall be MTR type consisting of aluminum clad plates enriched up to 20% in the U-235 isotope.

5.2.2 A standard fuel assembly shall consist of up to 14 fuel plates containing a, maximum of 180 grams of U-235.

Amendment No. 11

23 5.2.3 A control fuel assembly shall consist of up to 8 fuel plates containing a maximum of 103 grams of U-235.

5.2.4 Partially loaded fuel assemblies in which some of the fuel plates are replaced by aluminum plates containing no uranium may be used.

5.3 Fuel Storage 5.3.1 All reactor fuel assemblies shall be stored in a geometric array where keff is less than 0.8 for all conditions of moderation and reflection.

5.3.2 Irradiated fuel assemblies and fueled devices shall be stored in an array which will permit sufficient natural convection cooling by water or air such that the temperature of the fuel assemblies or fueled devices will not exceed 100°C.

Amendment No. 11