ML092930278

Massachusetts Institute of Technology, Response to Request for Additional Information, Dated 07/02/09

ML092930278
Person / Time
Site:	MIT Nuclear Research Reactor
Issue date:	10/09/2009
From:	Bernard J Massachusetts Institute of Technology (MIT)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MA6084
Download: ML092930278 (7)

Text

John A. Bernard, Ph.D.

Director of Reactor Operations ilur Massachusetts Institute of Technology 77 Massachusetts Avenue, NW12-208A Cambridge, Massachusetts 02139-4307 Phone 617.253-4202 Fax 617.253-7300 Email bernardj@mit.edu http://web.mit.edu/nri/www October 9, 2009 U.S. Nuclear Regulatory Commission Attn: Document Control Room Washington, DC 20555 Re: Massachusetts Institute of Technology; License No. R-37; Docket No. 50-20; Response to RAI (TAC No. MA 6084) dated 07/02/09

Dear Sir or Madam:

Enclosed is the response to the above RAI. Please contact either myself or Dr. Thomas Newton (617-253-4211) with any questions.

Sincerely,

a. Bernard, Ph.

, PE, CHP Director of Reacto Operations I declare under the penalty of perjury that the foregoing is true and correct.

Executed on 1

0

'4--

r--L Date SiL

gnue, Cc:

William B. Kennedy Project Manager Research and Test Reactors Branch A U.S. Nuclear Regulatory Commission

Answer to RAI The reactivity analysis was made with the coupled point kinetics-thermal-hydraulic code PARET-ANL [1,2]. This analysis was made assuming a 1.8 % AK/K ($2.30) reactivity insertion over a period of 0.5 s. The Seider-Tate correlation was used for single phase flow, the Bergles-Rohsenow correlation for two phase flow, and the transition model (IMODE=I) was used for transition from one to two phase. These correlations are among those included in benchmarking studies comparing PARET results with SPERT-I transients [2], IAEA Benchmark transients [3,4], and SPERT-IV transients [5]. The latest version of PARET-ANL (version 7.4) was used for the MITR calculations. Whenever modifications are made to the PARET-ANL code, results using a suite of several benchmarking cases are analyzed to confirm that any modifications remain within the benchmarking envelopes.

A 0.5 s ramp was used for evaluation. Although a 0.1 s ramp was used in previous analyses, this is thought to be unrealistic given that the in-core experiments are mechanically secured and a transient involving the catastrophic failure of the experiment would take some time before the experiment would be completely removed from the core. The 0.5 s ramp is a standard for fast reactivity transients and has been used for analyses of similar failures in reactors such as the National Bureau of Standards Reactor

[6], the Greek Research Reactor [7], and the Pakistani Research Reactor [8].

The inputs to the PARET model were those of the most conservative conditions: power of 6 MW, and conditions at the LSSS points (flow of 1800 gallons/min., power scram at 7.4 MW, period scram at 7 s., each with 0. 1 s delay). Operation at initial powers below 6 MW were also analyzed and found to be less limiting.

Uncertainties in the input of operating parameters were analyzed by varying relevant values by 5% in the most conservative direction (increased or decreased). These results are shown in Figure 1. In the nominal case, the cladding temperature increases to 83.4

°C, giving a large margin to the aluminum cladding softening point of 450 TC. Variation of the operating parameters each had a small effect on the peak temperature, with a 5%

increase in initial power (to 6.3 MW) having the largest effect, raising the peak cladding temperature to 85.6 TC.

The 5% values represent conservative variations on the various operating parameters (flow, power, channel width, and power peaking). The primary coolant flow rate indication is specified to be calibrated to within 2% of true flow. Primary AT indication (used with flow rate to calculate reactor power) has a calibration specification of 0.2 °C, or 3% at full power. Fuel manufacturing tolerances specify a no greater than -5%

variation on coolant channel width. Finally, power peaking was increased 5% beyond an already conservative hot channel (1.45 times average) with an additional maximum peaking factor of 2.2.

A similar variation was made to selected physics parameters, such as the moderator void coefficient and moderator temperature coefficient. These variations showed a minimal effect on the peak cladding temperature during the transient. Larger variations of these and other physics parameters were made in ref [8] with a conclusion that cladding and fuel temperature increases are relatively insensitive to variations in these parameters.

Analyses were also performed for natural convection at low power, but in all cases a scram occurred before significant heat could be added.

90 85 -

on ou

---

Nominal 75 5% flow decrease 65 i5%

Coolant channel width reduction

-60 5% Power increase 55 -

5% increase in Power peaking 45 -_-

40 1 0.00 0.50 1.00 1.50 Time (s)

Figure 1. $2.30/0.5 s reactivity insertion with parameters varied by 5%

References

1. C.F. Obenchain, "PARET -- A Program for the Analysis of Reactor Transients," Idaho National Laboratory, IDO-17282, January, 1969.

2. W.L. Woodruff, "The PARET Code and the Analysis of the SPERT-I Transients,"

ANL/RERTR/TM-4, 1982.

3. W.L. Woodruff, "A Kinetics and Thermal-Hydraulics Capability for the Analysis of Research Reactors," Nuclear Technology, 64, 1984

4. W.L. Woodruff, N. Hanan, R. Smith, and J. Matos, "A Comparison of the PARET/ANL and RELAP/MOD3 Codes for the Analysis of IAEA Benchmark Transients," Proceedings of the 1996 of the Reduced Enrichment for Research and Test Reactors meeting, Seoul, Korea, 1996.

5 W.L. Woodruff, N. Hanan, and J. Matos, "A Comparison of the RELAP/MOD3 and PARET/ANL and Codes with the Experimental Transient Data from the SPERT-IV D-12/25 Series," Proceedings of the 1997 Reduced Enrichment for Research and Test Reactors meeting, Jackson Hole, WY, 1997.

6. J. Carew, L. Cheng, A. Hanson, J. Xu, D. Rorer, and D. Diamond, "Physics and Safety Analysis for the NIST Research Reactor," BNL-71695-2003-IR, 2003.

7. C. Housiadas, "Lumped Parameters Analysis of Coupled Kinetics and Thermal-hydraulics for Small Reactors," Annals of Nuclear Energy, 29,.2001

8. R. Nasir, N. Mirza. And S. Mirza, "Sensitivity of Reactivity Insertion Limits with Respect to Safety Parameters in a typical MTR," Annals of Nuclear Energy, 26, 1999.

0

• PARET 7.4 MITR HEU core reactivity limit calculations Sep08 I

2-channel model; fast reactivity (step) insertion over 0.50 sec; I

fin heat transfer factor=l.9; 2-channel model I

k-fuel=70.0; k-clad=186; k-oxide=2.08 clad and oxide are separate; 0.5 mil oxide forced convection at 1800 gpm; initial power at 6.3MW o

Overpower trip at 7.4 MW; period trip 7 sec, with 0.1 sec delay 111111111111222222222222333333333333444444444444555555555555666666666666

1001,

-2 20 9

0 1

1

1002, 1

1 6

-1 0

99 MW RS

1003, 6.30-0 8.24430-3 1.18000+5

-33.0 9.01700-4 RF RC PW(2.31")

1004, 3.81000-4 8.89000-4 5.86740-2 5.28830-2 0.5683 0.00794

1005, 0.00794 0.0075 8.00-5 9.80664 0.01367

1006, 2.00 0.8000 1.0 992.00 0.0

1007, 3.6000-5 0.0 0.0 0.0 1.0 0.001

1008, 0.0 0.0005 0.001 0.03 0.05 0.05

1009, 1.4 0.33

1111, 0.047156 1.00 RELAP.

1112, 1

2

1.

0 0

2.260000+5 25.000 4227.0

1113, 0.40 0.1 7.400-0 0.0 111111111111222222222222333333333333444444444444555555555555666666666666 i account for fin FINF*

1114, 1.92 0.062

- 0.

0.

1.9 0.70 PERTP PTDLAY

1115, 7.0 0.1

2001, 0.0 0.0 70.0 0.0.

.0.0

2002, 0.0 1100.0 1.92600+6 0.0 0.0

!clad

2003, 0.0 0.00 186.0 0.0 0.0

2004, 0.0 1100.0 2.10165+6 0.0 0.0

!oxide

2005, 0.0 0.0 2.08 0.0 0.0

2006, 0.0 1100.0 2.10165+6 0.0 0.0 i

111111111111222222222222333333333333444444444444555555555555666666666666

3001, 9.52500-5 5

1 0.967

3002, 3003,

4001,

! peak ICLAD 2.54000-4 7

2 0.0 7

0.63500-5 9

3 0.0 2.8415-2 20 channels; assumed 1.45:1 peaking Vs.

avg.

! peak channels

5100, 1

5100, 5101,

5102, 5103,

5104, 5105,

5106, 5107,

5108, 5109, 0.9 0.0651 2.201 2.231 2.262 2.311 2.360 2.408 2.455 2.286 represent the 0.

0.9 1.9193 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 4 hottest channels see MHA 2.00660-3 0.01 0.55 void coef temp coef 0.9020 2.1070-2 0.3875 0.3875 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 0.65

5110, 5111,

5112, 5113,

5114, 5115,

5116, 5117,

5118, 5119,

5120, 5121,

5200, 5200,

5201, 5202,

5203, 5204,

5205, 5206.,

5207, 5208,

5209, 5210,

5211, 5212,

5213, 5214,

5215, 5216,

5217, 5218,

5219, 5220,

5221, 2.118 1.714 1.309 1.084 0.859 0.736 0.613 0.561 0.510 0.436 0.363 0.181 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 0.9 0.0651 1.201 1.189 1.177 1.236 1.295 1.316 1.338 1.302 1.267

1. 180

1. 093 1.019 0.945 0.867 0.790 0.709 0.628 0.597 0.567 0.283 0.

0.9 1.9193 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 2.00660-3 0.6000 0.3875 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 1.45 0.99 2.1070-2 0.3875 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.55 0.65

6001, 3.30700-2 1.24000-2 2.19010-1 3.05000-2 1.95940-1 1.11000-1

6002, 3.94950-1 3.01000-1 1.15040-1 1.1400 4.19900-2 3.0100

9000, 3

ramp ends at 0.5 sec

$2.3

9001, 0.0 0.0 2.30 5.00-1 2.30 10.0

10000, 2

! forced convection at 1800 gpm G=2291.6 kg/m2 s for 24 elements

10001, 2291.6 0.0 2291.6 10.0

11000, 2

11001, 0.0 58.0 0.0 4000.0

12000, 2

12001, 0.0 0.0 0.0 10.0

14000, 4

!14001, 1.00-7 0.0 5.00-8 0.19 1.00-6 0.40

!14002, 5.00-5 2.0 larger time step-all times changed from 1.-6 111111111111222222222222333333333333444444444444555555555555666666666666

14001, 1.00-6 0.0 1.00-6 0.30 1.00-6 0.60

14002, 1.00-4 1.4

16000, 16001,

17000, 17001,

18000, 18001, 2

0.01 3

1.00 2

0.0 100 0.0 0.0 0.0 1.0000

-14.2 0.01 1.0 0.5683 100 10.0 10.0 1.0