ML20137B063

Forwards Addl Info to Support 850428 & 840801 Requests for Exemptions from NUREG-0737,Items II.F.1 & II.F.1-2 Re Upper Range of Noble Gas Concentration Monitoring & Design Basis Shielding Envelope for Radioiodine Sampling

ML20137B063
Person / Time
Site:	La Crosse File:Dairyland Power Cooperative icon.png
Issue date:	11/08/1985
From:	Taylor J DAIRYLAND POWER COOPERATIVE
To:	Zwolinski J Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.1, TASK-TM LAC-11234, NUDOCS 8511260170
Download: ML20137B063 (10)

Text

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h D ' DA/RYLAND h [k COOPERAT/VE

• P.O. BOX 817 2615 EAST AV ' SOUTH . LA CROSSE. WISCONSIN S4601 (608) 788 4 000 November 8, 1985 In reply, please refer to LAC-11234 DOCKET NO. 50-409 Mr. John Zwolinski, Chief Operating Reactors Branch No. 5 Director of Nuclear Reactor Regulation

~ Division of Operating Reactors U. S. Nuclear Regulatory Commission

-Washington, DC 20555 ,-

SUBJECT:

DAIRYLAND POWER COOPERATIVE (DPC)

LA CROSSE BOILING WATER REACTOR (LACBWR)

PROVISIONAL OPERATING LICENSE NO. DPR-45 FOLLOW-UP ON REQUESTS FOR EXEMPTION FROM NUREG-0737, ITEM II.F.1, ATTACHMENT 1, POSITIONS 1 AND 2 (UPPER RANGE OF NOBLE GAS CONCENTRATION MONITORING), AND ITEM II.F.1-2 (DESIGN BASIS SHIELDING ENVELOPE).

REFERENCES:

(1) DPC Letter, Linder to Zwolinski, LAC-10783,

. dated April 28, 1985.

(2) DPC Letter, Linder to Crutchfield, LAC-10104, dated August 1, 1984.

(3) DPC Letter, Linder to Diggs, LAC-10848, dated May 9, 1985.

(4) LACBWR Technical Specification Table 4.5-1, Action (1).

(5) 10CFR170.12.

L =(6) LACBWR Final Safety Analysis Report, Volume.II, Section 15.

(7) DPC Letter, Linder to Paulson, LAC-10251, dated October 11, 1984.

Dear Mr. Zwolinski:

As indicated in our previous correspondence to you (Reference 1 and 2),

we requested two exemptiou from NUREG-0737 Item II.F.1 for upper range of noble gas concentration and design basis shielding envelope for radioiodine sampling in post-accident conditions.

We have'not, as of yet, received a formal review of these requested exemptions. This letter serves to provide you with additional information to

support our requests for exemptions found in References 1 and 2.

WPl.5.6'

'8512%kf j9 I

.P I L. .-

Mr. John' Zwolinski, Chief '

November 8, 1985 s Operating Reactor Branch #5 LAC-11234

'In Reference 1, we requested an exemption from Item II.F.1 Attachment 1 Positions 1 and 2, and Table II.F.1-1, Design Basis Maximum Monitoring Range of 105 pCi/cc for effluent noble gas concentration. We indicated that with a 100 percent release of noble gases from the fuel to the containment building, 3.61 x 107 Ci of activity due to. noble gases would be released into 7480_ cubic meters of containment free air spaces, resulting in a peak containment building noble gas concentration of about 4.8 x 103 C1/m3 . The noble gas -

activity is based upon noble gas source terms found in LACBWR Final Safety Analysis Report Table 15.6 " Core and Containment Building Fission-Product-Activity (Reference 6)." The peak noble gas activity is assumed to occur at times after the reactor would be shutdown, post loss of coolant accident, and after fuel rods were undergoing melting as described in Section 15.8 of Reference 6.

While this analysis does assume that fuel melting occurs, no fuel damage is expected to occur, if any one of the several Emergency Core Cooling System subsystems performs as designed (Reference 7). Therefore, this analysis is very unrealistic.

A core meltdown fraction of 18.2 percent, which resulted in a noble gas release of 24.4 percent of core inventcry was calculated and presented in the original LACBWR Safeguards Report, ACNP-62574, Section 14.3.3. Based upon ACNP-62574, Section 14.3.3.1, the first melting would occur in the center of fuel shroud section 1 (center of core), at about 200 seconds af ter the loss of coolant incident and reactor shutdown. All but the outer row of pins in this section would eventually melt. The temperature of the outer row of pins reaches a maximum temperature, at about 750 seconds after the loss of coolant incident. The maximum credible accident (MCA) has been evaluated for a very conservatively assumed 100 percent meltdown. Because of the inherent time delay (greater than about 15 minutes), between LOCA/ shutdown, peak fuel

~

melting conditions, and diffusion of the noble gases through the point of coolant loss into a pressurized containment, certain extremely short-lived noble gas nuclides (such as Kr-90-97 and Xe-137-144), which would be present in the core at time of shutdown, would be substantially decayed by the time >

peak noble gas' concentrations would be present inside the containment building free air volumes. Because of this, these extremely short-lived noble gas nuclides are not considered in this analysis. The shortest lived noble gas radionuclide considered in this MCA analysis is Xe-135m with a 15.6 minute half-life.

In Reference 1, we indicated that with a peak activity concentration of

'4.8 x 103 Ci/m3 inside containment, with the containment building isolated, as expected the peak noble gas concentration in the stack would be approximately 1.1.x 10 5 pCi/ce, assuming a designed basis containment leakage rate of 0.1 percent volume per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at 52 psig and no stack blowers in operation.

Other scenarios were described in Reference 1, which resulted in stack noble i gas concentrations of less than 1.1 x 103 pCi/ce.' Calculations are shown in Attachment 1. The post accident noble gas isotopic activity concentrations inside the containment building, as listed in Reference 6, are not

, significantly different than power corrected values listed in NUREG-0771.

. Using NUREG-0771 noble gas isotopes and activites,.and assuming uniform distribution of these noble gas activities released to containment free air

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Mr. John Zwolinski, Chief November 8, 1985 Operating Reactor Branch #5 LAC-11234 spaces, the analysis would result in a containment noble gas concentration of about 2.3 x 103 pCi/cc. This would correspond to a stack effluent noble gas concentration of about 5.1 x 102 pCi/ce, at design basis leak rates.

Therefore, based upon these analyses, it is not necessary to have stack noble gas monitoring capability of up to 1 x 10 5 pCi/cc (Xe-133 equivalent).

As indicated in Reference 1, we request that we be permitted, based upon our lower source terms and our Technical Specifications Table 4.5-1, Action (1),

to have a design. basis maximum range requirement for our high range noble gas effluent monitor of 1.5 x 103 pCi/cc (Xe-133 equivalent).

In Reference 2, we requested an exemption from Table II.F.1-2, Design Basis Shielding Envelope for clarification (2) of "100 pCi/cc of gaseous radioiodines and particulates, deposited on sampling media, 30 minutes

. sampling time'with an average gamma energy (E) of 0.5 MeV".

Based upon the radioiodine concentrations listed in Table 15.6 of Reference 6, the maximum radioiodine concentration at the stack effluent isokinetic sampling line inlet.would be about 25 pCi/cc. This assumes that the containment building radioiodine peak concentration, following the MCA, reaches 1.183 x 103 Ci/m3 , and containment leakage is 0.1% per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at an initial pressure of 52 psig with no stack blowers providing dilution air.

With one stack blower in operation, the peak radioiodine concentration at the

-stack isokinetic sample inlet would be about 6 x 10-3 pCi/cc. At these concentrations, the dose limits specified by 10CFR50 Appendix A GDC-19 would not be exceeded for post accident radioiodine sampling for a 30 minute sample time. These calculations are found in Attachment 2.

In December 1984, your review group posed some questions concerning stack blower operability post accident. The stack blowers would become inoperable if there was a loss of offsite power at the time of the MCA. According to NUREG/CR-3591, the probability of loss of offsite power for a BWR is about 1.9 x 10-2/ year. The probability of this occurring, at the same time as an MCA would be even lower. Nonetheless, our calculations indicate that even with no stack blowers in operation, the peak radioiodine concentration in the stack would be about 25 pCi/cc. The combination of radioiodine and particulate concentrations would be less than 27 pCi/cc.

As required by Reference 5, payment for review of these requests for exemption from NUREG-0737, Item II.F.1 have been sent to you previously

~(Reference 2 and 3).

If you have any additional questions, please contact us.

Sincerely, DAIRYLAND POWER COOPERATIVE i

dE James W. Taylor General Manager l

l JWT:PWS:sks

!- WPl.5.6 L

k 4 Mr. John--Zwolinski, Chief November 8, 1985

-Operating Reactor Branch #5 LAC-11234 Attachment ec: J. G. Keppler, Region III John Stang,' LACBWR Project Manager

-NRC Resident-Inspector WP1.5.6 -

3-e__________._____________-___

ATTACHMENT 1 NOBLE GAS SOURCE TERMS INSIDE STACK FOLLOWING AN M7A FOR NUREG-0737 TABLE II.F.1-1 1A. Containment- Free Atmospheric Noble Gas Source Term: Peak noble gas concentrations inside containment. building after a maximum credible accident assuming translocation of 100% core inventory cf noble gases to containment free a.1r spaces (7480 m3 ).

Peak (1) Containment Building Radionuclide (i) Core Inventory (mci) Concentration, C. (Ci/m 3) 133 Xe 9.220 1233.0 135Xe 8.280 1107.0 88 Kr 5 .3 30 712.6 87Kr 3.770 504.0 13 5"Xe 2.330 311.5 85"Kr 1.400 187.2 84mKr 0.774 103.5 131"Xe 0.042 5.6 85Kr 0.028 2.0 133mXe 5.000 668.5 Ei 36.174 mci 4834.9 Ci/md (LCi/cc)

B. Concentration of Noble Cases in Stack With ho Bldwers in Operation: The peak concentration in the stack assuming containment isolation occurs and with design basis leak rate (0.1% of containment volume per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with pressure at 52 psig (initial) and no stack blower operation would be approximately as follows:

Pjt x ICi = ECf-P1 14.7 psia x 4834.9 tCi/cc = 1.07 x 103 pci/ce.

(52 + 14.7) psia The final stack effluent. noble gas concentration, ICg, is due to containment atmospheric expansion inside plant air spaces and/or the stack plenum and does not take into consideration additional dilution within the stack plenum or stack prior to the isokinetic sampling nozzle, for the

. post accident high range noble gas monitor. In this regard, this noble

-gas concentration is ultra-conservative.

-C. Concentratioa of Noble Cases in Stack With Blowers in Operation:

'The peak concentration in the stack assuming containment isolation occurs, and with design basis leak rate (0.1% of containment volume per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with pressure at 52.0 psig (initial) and with 1 or 2 stack blowers

__ . m._ , . . . - _ _ . _ - _ _ .

ATTACHMENT 1 (continued) in operation ~would be approximately as follows:

ECf x'Fg = IC, F rs where:.ECf = 1.07 x 10 3 pCi/cc Frs = stack flow rate w/

1 blower: 1.65 x 107 cc/see 2 blowers: 3 x 107 cc/sec Fri = containment leakage initial flow rate

_ (52.0 + 14.7) psia x 0.001 x 7480 m3 x 106 cc x 1.16 x 10-5 day = 394 cc/see 14.7 psia 7 see ECs = Peak stack concentration, pCi/cc 1 Blower 1.07 x 103 pCi/cc (394 cc/sec) = 2.6 x 10-2 pCi/cc (1.65 x 10/-cc/sec) 2 Blowers 1.07 x 103 pCi/cc (394 cc/sec) = 1.4 x 10-2 pCi/cc (3 x 10' cc/sec)

. ._ _ _. . ~_ _ _ _ . _ _ _ _ ___

..._ k' ATTACHMENT 2 LACBWR DESIGN BASIS SHIELDING ENVELOPE FOR NUREG-0737 TABLE II.F.1-2

, - I.: Containment Free Atmospheric Radioiodine Source Term: Assume 25% of core inventory radioiodines translocated to containment building free air spaces.(7480 m3) and uniformly mixed.- Radioiodines are assumed to be in-gaseous state (e.g. no. C s1 or other iodous particulates formed).

Peak ,

Containment Radionuclide Core (1) Containment Concentration (1) Inventory-(mci) Inventory (mci) (Ci/m3) frI 1311 4.160 1.040 139.0 0.1175 1321- 6.180 1.548 207.0 0.1746 1331 9.180 2.304 30 8.0 0.2593 1341- 7.960 1.997 267.0 0.2249 1351 7.820 1.967 263.0 0.2206 Zi- - 35.300 8.856 1183.0 Efr I 1.0000 (1)

References:

LACBWR Final Safety Analysis Report, Table 15.6.

II. Containment Building Leak Rate: '(Assume Design Basis Leak Rate-of 0.1% of containment volume per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at 52 psig containment atmospheric pressure (initial)):

The ' design leakage rate f rom containment is 50 standard f 3t /hr.

50 SCFH x 14.7 psia = 11 ft /hr 3 @ 52 psig.

(14.7+52) psia

-11 ft 3/hr x 0.02833 m3 x 106 cc x 1 hr = 5200 cc/ min.

ftJ liI 60 min.

III. , Case 1 A. -Concentration of Radioiodines at the stack sample systems with no stack blowers in operation:

l The flow rate through the stack monitor (SPING) is about 50,000 cc/ min.

The flow rate through the stack sampling system, including pump flow for PASS system, is about 9 ft3/ min or 2.5 x 10 5 cc/ min.

p f' Assume all containment leakage is taken up by the stack isokinetic sample nozzle (conservative). The effective dilution from the containment iodine concentration is :

5200 cc/ min x 1.183 x 103 Ci/m3 x 1 uci/cc = 25 pCi/cc 2.5 x 103 cc/ min 1 Ci/mJ i.

.. .-. . .- =__.

h ATTACHMENT 2 (continued)

B. Radioiodine Activity in; post accident stack monitor (SPING) sample Ag-Zeolite cartridge af ter 30 minutes of sampling:

Assumptions:

SPING is sampling isokinetically fr = SPING flow rate 50,000 cc/ min.

p = Pressure correction factor: 0.85 1- = Line Loss Correction factor: 0.75 t = Sample Time: 30 minutes. .

Ci = Activity con' centration: 25 pCi/cc a = Iodine effective absorption in sample media: 0.95 Ai = Activity in sample media per unit time, t.

At = Cia frpit-Ai = 25 pCi/cc x 0.95 x 50,000 cc/ min x 0.85 x 0.75 x 30 min.

Ai = 2.271 x 10 7 pCi Ai = 22.71 Ci (2)

C. Gamma Dose Rate from Sample Cartridge: Eff r I = 6.90 R-cm2 /hr mci Ef f rI = 0.690 R/hr at 1 meter /Ci 10 0.690 x 22.7 Ci = 15.7 R/hr @ l meter 15.7 R/hr = 1570 R/hr @ 10 cm (0.10)4 (2)

Reference:

The Health Physics and Radiological Health Handbook, Nucleon Lectern Assoc., 1984.

ATTACTMENT 2 (continued)

D. Estimated Extremity and Whole Body Dose Equivalents:

L Dose Equivalents from 30 minute Sample Time

• Whole Body Extremity

1. Background gamma 0.29 Rea 0.29 Rem radiation

2. Cartridge removal,'

transport,. disassembly

and' analysis- 2.10 Rem 10.57 Rem

!- TOTAL ~(Rem) 2.39 Rem 10.86 Rem

• At 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after accident, the initial radioiodine concentration has

- been reduced by a factor of 4.15 due to decay of 1321 ,134I 2 and 135 1

~

The T for E radioiodine has been reduced from 6.90 R-cm /hr-mci to 2.95 R-ca@/hr/mC1. 132I and 134I are contributing < 0.05% and 135I is contributing < 8.0 % of total dose from radioiodines deposited on the cartridge.

E.- Particulate contribution to filter paper in 30 minutes sample time, assuming 1% release from core to containment free air spaces: = 1 C1.

(..

! 'This particulate activity represents only about 4% of the radioiodine activity and whole body / extremity doses, from filter handling, and would constitute a fraction of.the doses received, while handling the cartridge containing radioiodines.

IV. Case 2:

A. Concentration of Radioiodir.es at the stack sampling systems with L one and two stack blowers in operation:

50 ft 3/hr x 14.7 psia x 0.02833 m3 x 106 cc x 1 hr = 86.72 cc/sec 66.7 psia ftJ LEI 3600 sec I blower:

1.183 x 103 pCi x 86.72 cc/see __ = 6.2 x 10-3 pCi/cc t ,,

cc 1.65 x 10' cc/sec 2 blowers:

1.183 x'103 pCi x 86.72 cc/sec = 3.4 x 10-3 pCi/cc ce 3.x 10' cc/see J~

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e-ATTACHMENT 2 (continued)

B. Radioiodine Activity deposited on sample media af ter 30 minutes sampling (assume 1 bicwer in operation):

At '= 6.2 x 10-3 pCi/ce' x 0.95 x 50,000 cc/ min x 30 min x 0.85 x 0.75 x 10-6 Ci/pci = 5.6 x 10-3 Ci C. Camma Dose Rates from Sample Cartridge:

0.690 R/hr @ im per Ci x 5.6 x 10-3 = 0.004 R/hr @ 1 meter

= 0.384 R/hr @ 10 cm D. Estimated Whole Body and Extremity Dose Equivalents:

Whole Body: (0.29 + 0.001) = 0.291 Rem Extremity: (0.29 + 0.01) = 0.30 Rem i-

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