PY-CEI-NRR-0678, Forwards Util Evaluation of NUREG-1169 Applied to Determine Relative Advantages of Isolated Condenser Configuration. Rept Demonstrates Offsite Dose Reduction & Improved Reliability by Operating in Isolated Condenser Mode

Forwards Util Evaluation of NUREG-1169 Applied to Determine Relative Advantages of Isolated Condenser Configuration. Rept Demonstrates Offsite Dose Reduction & Improved Reliability by Operating in Isolated Condenser Mode

ML20236J401
Person / Time
Site:	Perry
Issue date:	07/31/1987
From:	Edelman M CLEVELAND ELECTRIC ILLUMINATING CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
RTR-NUREG-1169 PY-CEI-NRR-0678, PY-CEI-NRR-678, NUDOCS 8708060164
Download: ML20236J401 (8)

Text

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THE CLEVELAND ELECTRIC ILLUMIN ATING COMP ANY q P.O. BOX 5000 - CLEVELANo, OHIO 44101 - TELEPHONE (216) 622-9800 - l ILLUMINATING DLDG. - 55 PUBLIC SQUARF Serving The Best Location in the Nation MURRAY R. EDELMAN SR VICE PRESIDENT NUCLEAR July 31, 1987 PY-CEI/NRR-0678 L j

, Document Control Desk {'

l U.S. Nuclear Regulatory Commission l Washington, D. C. 20555 Perry Nuclear Power Plant l Docket No. 50-440 '

Evaluation of Perry MSIV Leakage Control System per NUREG - 1169 l

i Gentlemen:

CEI has conducted a Plant-specific eve.luation of NUREG-1169, "An Evaluation of Boiling Water Reactor Main Steam Isolation Valve Leakage and Effectiveness of Leakage Treatment Methods."

NUREG 1169 evaluates the effectiveness of the of MSIV Leakage Control System (LCS), specifically addressing concerns with LCS capacity limitations and reliability. Alternatives to LCS operation are also presented. By allowing MSIV leakage to pass to the condenser via steam drain lines, offsite doses are shown to be reduced several orders of magnitude. Due to the fact that no operator action or active component function is required, system availability is also increased substantially, and there is no inherent limitation on system capacity.

We have applied specific portions of this NUREG 1169 study to determine the relative advantages of the " isolated condenser" configuration. The attached report describes this Perry-specific analysis, which demonstrates significant of f site dose reduction, improved reliability, and reduced operator actions post accident by operating in the isolated condenser mode. Our analysis of i

the NUREG also indicates variations'in the assumptions other than system configuration could be accommodated. These are presently being evaluated by CEI.

8708060164 s70731 Oo\

PDR ADOCK 05000440 ,

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. Document Control Desk -2'- PY-CEI/NRR-0678 L

. July 31, 1987 I

The enclosed evaluation is being provided for NRC staff review.- We propose a meeting on this subject at your earliest convenience, in August. . We will submit a request for license amendment to eliminate the Perry LCS and operate in the isolated condenser mode, following discussions with NRC.

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'We will contact the Perry Project Manager to set up the meeting. Please feel free to contact me if you have any. questions.-

Very truly ou s, U

Murray R. Edeltan Senior Vice President Nuc1 car Group MRE:njc Enclosure / Attachments i cc: T. Colburn K. Connaughton

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EVALUATION OF PERRY HSIV LEAKAGE CONTROL ALTERNATIVES Summary and Conclusions The Main Steam Isolation Valve Leakage control System (MSIV-LCS) is designed to direct valve leakage to the secondary containment volume, which is processed by mixing in a split recirculation / exhaust mode, with exhaust air charcoal filtered to reduce offsite releases.

NUREG 1169 " Resolution of Generic Issue C-8, An Evaluation of Boiling Vater Reactor Main Steam Isolation Valve Leakage and the Effectiveness of Leakage Treatment Methods," has evaluated the effectiveness of alternate BVR main steam isolation valve (MSIV) leakage treatment methods, including a comparison of post-accident performance between LCS operation and a mode of operation described as " isolated condenser." Along with an improvement in net availability from 80% to 93%, respectively, the isolated condenser mode reduced public exposure from MSIV leakage by several orders of magnitude.

This report concludes that there are relatively low public risks from MSIV leakage without leakage control systems, even at relatively high leak rates.

A comparison of plant design parameters, control room and offsite dose results between the Perry Nuclear Power Plant and the referenced plant in NUREG 1169 has been performed. This comparison concluded that NUREG 1169 methodology and results could also be applied to Perry, and that the MSIV-LCS could be eliminated with a net reduction in offsite dose. It is therefore proposed that the MSIV-LCS be eliminated.

Safety Analysis CEI has performed a review of NUREG 1169, and determined that the Isolated Condenser leakage treatment method using open drain valves described in Section 4.3.1. is applicable to the Perry design. The Perry Unit 1 plant has Main Steam drain valves that open on a turbine trip, and also on loss of power or air supply. Thus, as determined in Section 4.3.1, this approach qualifies as a completely passive method since no operator action is required to use this pathway.

Perry FSAR Section 15.6.5 defines the present design-basis accident (DBA) and computes control room and offsite doses using the MSIV-LCS. The doses are shown in Attachment 1. The proposed alternative to using the MSIV-LCS is to operate in the isolated condenser mode as described in NUREG 1169. For this l comparison, calculation assumptions are the same except for the processing of '

the MSIV leakage. Therefore, only the net contribution from MSIV-LCS compared to isolated condenser was analyzed.

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To determine the dose contributions from the isolated condenser leakage path,  !

NUREG 1169 was used as a basis appropriately modified for Perry design l differences: )

1 (a) The isolated condenser. configuration is de cribed in NUREG 1169 Sections 4.3.1, 5.3.9, and Figures 5.9 ana 5.10. Following automatic reactor shutdown at Perry, open drain paths are available from each main steam line to the condenser without the'need for operator action. The net availability for isolated condenser would therefore be higher than calculated from Figure 5.10. No leakage.

paths to atmosphere, other than the assumed main turbine-generator shaft gland seals, exist at Parry. j (b) A summary of the important parameters which affect iodine transport and release through the isolated condenser are provided in

. Attachment 2. Based on plant similarities and greater. condenser-volume at Perry, it is concluded that NUREG 1169 decontamination factors can conservatively be applied to Perry as described below. i (c) For noble gases, whole body doses are conservatively based on isolated condenser holdup by normalizing NUREG 1169 results as described below.

CEI used the information available in the NUREG 1169 and adjusted the values to arrive at Perry site specific numbers. First NUREG 1169 data was analyzed to determine the unprotected baseline dose for the reference plant. NUREG 1169, Table 4.10 lists the Baseline Case dose assuting use of the Standby Gas Treatment System (SGTS) at the referenced plant. In order to determine what the dose vould be without using SGTS (unprotected dose), the SGTS reduction factor was eliminated by first duplicating the TACT III baseline calculation of NUREG 1169, then running the model without the SGTS reduction factor. Next, NUREG 1169, Table 4.13 data was extrapolated to determine what isolated condenser doses vould be at the reference plant with a 25 scfh/ valve MSIV leak rate. This value was used since it is the present Technical Specification limit at Perry.

Next, the isolated condenser dose for 25 scfh/ valve leakage was divided by the unprotected dose determined previously. This resulted in a dose reduction factor for the NUREG 1169 reference plant when 25 scfh/MSIV leakage was assumed.

This dose reduction factor vas then applied to the Perry specific unprotected dose assumed in the FSAR Accident analysis. Thus the Perry plant specific doses using the isolated condenser pathway were obtained. These doses are shown on Attachment 3. Comparing the results in Attachment 3 to the doses .

contributed to MSIV-LCS on' Attachment 1 show that the contribution of doses j due to the isolation condenser treatment path is less than doses analyzed j using the present MSIV-LCS. This is due to tne increased hold up time and i iodine removal in the condenser. This approximate amount that the applicable '

doses are decreased is also shown on Attachment 3.  ?

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Significant Hazard Analysis The standards used to' arrive at a determination that a request for amendment requires no significant hazards consideration are included in the Commission's regulations, 10 CFR 50.92, which state that the operation of the facility in accordance with the proposed amendment would not (1) involve a significant ..

increase in the probability or consequences of an accident previously evaluated, (2) create the possibility of a new or different kind of accident from any accident previously evaluated, or (3) involve a significant reduction in a margin of safety. CEI has reviewed the proposed change with respect to l, these three factors.

It is concluded that processing of Perry MSIV leakage post-LOCA in the isolated condenser mode results in lover doses than previously reported for i the LCS mode of operation due to iodine plate out on the pipes and condenser, and increased holdup time due to large condenser volume relative to leakage flow. In terms of significant hazard criteria:

(1) Accident probability or consequences of accidents previously evaluated are not adversely affected.- Accident mitigation is enhanced, both in terms of success probability and dose consequences. Figure 5.10 of NUREG 1169 shows a net reduction in isolated condenser availability due to required operator action.

At Perry no operator action is required for the isolated condenser mode. Drain valves on the main steam line vill open automatically on a turbine trip (also would fail'open upon loss of air, or power).

Since no operator action is required, the availability of this-leakage control path is higher. Comparison to the existing NUREG basis (Table 5.13) is more favorable for Perry.

l (2) A different kind of accident is not created. -No new accidents were addressed in NUREG 1169. The Perry Plant is consistent with the assumptions and analysis used in this document.

(3) Safe'ty margins are not reduced. In terms of net effect on public  !

radiation exposure, safety margins are increased.

Environmental Impact CEI has reviewed the proposed Technical Specification changes against the f criteria of 10 CFR 51.22 for environmental considerations. As shown above, the proposed change does not involve a significant hazards consideration, nor result in a net increase in the types or amounts of effluents that may be i released offsite, nor increase individual or cumulative occupational radiation exposures. Based on the foregoing, CEI concludes that the proposed Technical Specification changes meet the criteria given in 10 CFR 51.22(c)(9) for a categorical exclusion from the requirement for an environment impact 4 statement.

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1 Attachment 1 PY-CEI/NRR-0678 L i

1 EXISTING PERRY DESIGN BASIS ACCIDENT DOSE CONTRIBUTION FROM HSIV'S <

i Whole Body Gamma Inhalation Beta Skin (2)

Dose (Rem) Dose (Rem) Dose (Rem) j I

Offsite Doses  !

Acceptance Criteria GuidelinesII) 25 300 N/A Exclusion Area (2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />) 1.05 10.2 ---

(863 Meters) I Lov population zone (30 days) I 0.36 2.8 ---

(4,002 Heters)

Control Room Doses (30 days)

Acceptance Criteria Guidelines ( ) 5 30 75 Calculated 0.33 0.77 6.27 (1)

The bases for evaluating maximum radiation exposures to Perry personnel and members of the general public are summarized in the USNRC Standard Review Plan (NUREG 0800) and the Perry FSAR Section 15.6.5. Criteria for evaluating radiological consequences to the general public are based on 10 CFR 100; calculated doses totaled from all release paths are acceptable if resultant thyroid and whole body doses for the design basis accident fall within the guidelines values specified in 10 CFR 100.11.

Acceptance criteria for Perry control room habitability are contained in  ;

10 CFR 50 Appendix A Criterion 19, and Perry FSAR Section 15.0.3.1.3.

l (2) Unprotected beta skin dose; no credit is taken for any reduction afforded by clothing.

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Attachment 2 PY-CEI/NRR-0678 L I0 DINE REMOVAL PARAMETERS PERRY VS NUREG 1169 REFERENCE PLANT PERRY NUREG-1169 Plant Type BVR-6 BWR-5 Mark III Mark II Proposed MSIV Leakage Pathway Isolated Isolated Condenser Condenser Steam Line Details Number / Pipe material 4/ carbon steel 4/ carbon steel Pipe Size, in. 28 30 l Vall Thickness, in. 2.406 1.375 '

Insulation Thickness, in. 3 1/2 4 Insulation Thermal 0.02 0.02 Conductivity (Ambient), Btu /ft-hr Number of Pipe Supports 19 29 Support Spacing, Ft. 1 min. 8 min.

29 max. 35 max.

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Turbine Generator Supplier GE GE Design Power, MVt 3,729 3,463 Design Power, MVe gross 1,250 1,205 Generator speed, rpm 1,800 1,800 Design steam flow, lb/hr 15.4 x 10 6 15.0 x 10 6 Turbine inlet pressure, psia 965 970 Main Condenser 6 6 Heat removal capacity, Btu /hr 7,847 x 10 7,702 x 10 Condenser Free Volume, ft 130,000 120,000-Condenser horizontal 2 deposition area, ft 280,000 252,000

. , . . . l Attachment 3 PY-CEI/NRR-0678 L DESIGN BASIS ACCIDENT DOSE CONTRIBUTION USING ISOLATED CONDENSER Whole Body Gamma Inhalation Beta Skin I*)

Dose (Reml__ Dose (Rem) Dose (Rem)

Offsite Doses Exclusion Area (2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />) 7.3E-5 1.2E-3 ---

(863 Meters)

Low population zone (30 days) 5.7E-3 4.8E-3 -

(4,002 Meters)

Control Room Doses (30 days) 2.1E-3 9.7E-4 3.7E-2 DECREASE IN DOSE BY USING ISOLATED CONDENSER Whole Body Gamma Inhalation Beta Skin (*)

Dose (Rem) Dose (Rem) Dose (Rem)

Offsite Doses Exclusion Area (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) 1.05 10.2 ---

(863 Meters)

Low population zone (30 days) .35 2.8 ---

(4,002 Meters)

Control Room Doses (30 days) .328 0,769 6.23 Unprotected beta skin dose; no credit is taken for any reduction afforded by g clothing.