ML20198N416

MSIV Alternate Leakage Treatment Pathway Seismic Evaluation

ML20198N416
Person / Time
Site:	Hope Creek
Issue date:	11/12/1998
From:	EQE INTERNATIONAL
To:
Shared Package
ML20198N395	List: ML20198N390 ML20198N398 ML20198N416
References
NUDOCS 9901060122
Download: ML20198N416 (43)

Text

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! A ternate l.ea(age "reatment 'a"1way i Seismic Eva uation l

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Se.ismic Eva uation I

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@ 1998 by EQE International ALL RIGHTS RESERVED Except for use by the Nuclear Regulatory Commission and Public Service Electric & Gas Company in activities related to Technical Specification changes associated with this document, no part of this document may be reproduced or transmitted in any form or '

by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval systems, without permission in writing from EQE Intemational.

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Table of Contents l

1 l Pace EXECUTIVE

SUMMARY

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1. SCO P E OF S EISMIC EVALUATIONS ................. .................. ............... 1-1 1.I P ipin g Wal kdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 1 -1 1.2 Turbine Building Seismic Design review ........................................ 1-2 l 1.3 Condenser Review and Analysis ......... ........ . ... .. .... .............. ......... 1-2 i 1

1.4 Alternate Drain Path Piping and Support Analysis ......................... 1-2

2. TU R B I N E B U 1 LD I N G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1 ........

2.1 Building Description and Structural Systems ................................. 2-1 2.2 S eis mic D e sig n Ba si s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

3. 31 TU R B I N E C O N D E N S E R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.1 Hope Creek Condenser Design Basis ....... ................................... 3-1 3.2 Anchorage ............................................................................... 3-2

4. M SIV LEAKAG E CONTROL PI PIN G ..................... ...... . ................... ........ 4-1 4.1 M ain S t e a m Pipi n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4.2 Non-Seismic Piping Evaluation ..... ................................................ 4-2 4.3 Comparison of Hope Creek Design SSE Spectra with the Ea rthq uake Database Plants ........................ . .... .... ................ ....... 4-4 4.4 Alternate Drain Path Seismic Analysis .......................................... 44 1

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! Table of Contents l Paae i Tables i I

21(a) Design Loading Combinations l l Load Combinations for Reinforced Concrete Non Seismic Category 1 Structures .................................................... . .. . 2-4 2-1(b) Design Loading Combinations

' Load Combinations for Structural Steel and Concrete Masonry Non-Seismic 1

C atego ry I Stru ctu res( 1 ) . . . .. . . . . . . . . . .. . . . . . . . . . . . .. .. . . . . . . . . . . .. . . . . .. . . . . . ... . . . . . . . . . . . . .. . . 2-5 '

1 2-2 D e sig n C o d e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 j

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4-1 Hope Creek MSIV Walkdown Outliers Summary Sheet ............................ 4-6 4-2 Hope Creek Attemate Drain Path Piping Design Parameters ................... 4-7 43 Earthquake Experience Database Piping Design Parameters .................. 4-8 i 4-4 Comparison of Hope Creek Piping Design Parameters with Earthquake Experience Database Piping Design Parameters ..................................... 4-9 Figures 1-1 HCNP MSIV seismic verification boundary ........................ ...................... 1-4 3-1 Size comparison of Hope Creek condenser with database condenser ...... 3-4 32 Comparison of Hope Creek condenser with database condensers ........... 3-5 3-3 Comparison of Hope Creek condenser plan dimensions with

! da taba se conde nse rs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . ..3-6 .

3-4 ' Schematic plan view of Hope Creek condenser anchorage ...................... 3-7 P:\200235.01Hcmsiv. Doc Iii

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Table of Contents i

Paae y Figures '

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i 5 Comparison of Hope Creek condenser anchorage with data base conden se rs . . .. . . . . . .. . . . . . . . . . . . .. . . . . . . .. . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . .. . .3-8 .....

3-6 Comparison of Hope Creek condenser anchorage l

j with database condense rs . . . . . . . . . . . ... .. . . ... . . . . .. . .. . .. . . . . . . . . . . . . . . . . .. .. . . . . . . .. . .. . .. . . . . . 3-8 l

! '4-1 Comparison of Earthquake database sites and H ope C ree k S S E sp ectra . . . . . . . . . . . .. . . . . . .. . . . . . . . .. .. . . . . .. . . .. . ... . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 4-10 4-2 D/t rations for Hope Creek alternate drain path piping .

and selected database piping .. ........... .... .......... .. ........ ..... ................. ... ... . . 4-11 l

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Executive Summary The evaluation described in this report was performed to document the seismic design adequacy of the Main Steam isolation Valve (MSIV) Alternate Leakage Treatment Pathway and its components.

Some of the components being relied upon to establish the Alternate Leakage Treatment Path were not designed to seismic Category I requirements. The General Electric BWR Owners Group (BWROG) study documented in NEDC-31858P outlines the earthquake experience methodology for evaluation of systems and components for the MSIV ) Altemate Leakage Treatment Pathway utilized in this study.

The seismic adequacy of the Alternate Leakage Pathway has been established based on earthquake experience data to demonstrate seismic ruggedness of the systems and components, plant specific seismic walkdowns to identify potential seismic vulnerabilities and engineering analyses to evaluate seismic performance of systems and components.

This report summarizes the scope, the methodology and some of the results of the seismic adequacy review and evaluations of the MSIV Leakage Alternate Treatment Pathway and its components.

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1. Scope of Seismic Evaluations The primary components to be relied upon to establish an Alternate Treatment Pathway l from the MSIV's to the turbine condenser are: (1) the high pressure turbine condenser,

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(2) the main steam lines from the MSIV's to the outboard third Main Steam Isolation valves, and (3) the main steam drain line piping to the condenser. The seismic verification boundary was established by Hope Creek system engineers using criteria l outlined in NEDC-31858P. The boundary is established upstream of the condenser by utilizing existing valves to limit the extent of the uismic verification walkdown. The seismic verification boundaries are shown in Figure 1.1.

1.1 Piping Walkdown A seismic verification walkdown was performed to assure that the main condenser and steam piping systems and components that are not seismically analyzed fall within the bounds of the design characteristics of the seismic experience data base contained in Appendix D to the BWROG Report for increasing MSIV Leakage Rate Limits and Elimination of Leakage Control System NEDC-31848P. The seismic experience database of piping and equipment designs have demonstrated good seismic performance.

The walkdowns of Hope Creek systems verify that systems and components have design attributes similar to those in the earthquake experience database. Conditions or piping design attributes that were outside the bounds of this conventional piping that resulted in component damage in the database plants were noted during the walkdown.

These potential seismic vulnerabilities were identified as " outliers" for subsequent evaluation and resolution. These " outliers" and their resolution are summarized in Table 4-1.

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1. Scope of Seismic Evaluations i

1.2 Turbine Building Seismic Design Review l

Pedormance of the turbine building during a seismic event is of interest to the issue of MSIV leakage only to the extent that the building structure and its intemal components should survive and not degrade the capabilities of the selected main steam and I condenser pathway components. A BWROG survey of this type of industrial structure j has, in general, confirmed that excellent seismic capability exists. There are no known I _ cases of structural collapse of either turbine buildir.Js at power stations or structures of similar construction. l The Hope Creek tarbine building is classified as Nonseismic, however, codes and i criteria similar to those used for Seismic Category I structures, were used for the l structural design of the entire building. The turbine building was dynamically analyzed l and designed to accommodate an SSE event.

1.3 Condenser Review and Analysis Analyses of the Hope Creek condenser and comparisons with database condensers

. were performed. The condenser design and anchorage are shown to be similar to those I at facilities in the earthquake experience database that have experienced earthquakes in excess of the Hope Creek design basis SSE. Anchorage calculation performed for the Hope Creek condenser demonstrate adequate capacity for the imposed demand of the design basis SSE.

1.4 Alternate Drain Path Piping and Support Analysis The piping relied upon to establish an Alternate Treatment Pathway includes both seismically analyzed and non-seismically designed systems. Analyzed lines included the Main Steam Line (from the MSIV to the turbine stop valve) and portions of various main

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steam branch lines to the isolation valves for the branch.

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!. Portions of main steam drain system piping designs that have not been seismically analyzed were reviewed to demonstrate that piping and supports fall within the bounds of design characteristics found in selected conventional power plant steam piping.

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1. Scope of Seismic Evaluations I

t The non-seismic designed portion of the alternate drain path to the condenser was also seismically analyzed to demonstrate that adequate strength and design capacity exist l

for piping components and support designs. The Alternate Leakage drain piping and supports were demonstrated to have adequate capacity for an SSE seismic event. l l

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1. Scope ofSeismic Evaluations til14MS M '. AuxRuvy TM HV-FoneA us-une A usv-t cv.s y DT4. _ , _ _ _ _ _ _ p _ _ _ 4 _ _ _H _ .H ~

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2. Turbine Building l Performance of the turbine building during a seismic event is of interest to the issue of MSIV leakage only to the extent that the building structure and its internal components should survive and not degrade the capabilities of the selected main steam and condenser pathways. A BWROG survey of this type of industrial structure has, in general, confirmed that excellent seismic capability exists. There are no known cases of I structural collapse of either turbine buildings at power stations or structures of similar construction.

The Hope Creek turbine building is classified as Nonseismic, however, codes and criteria similar to those used for Seismic Category I structures, were used for the structural design of the entire building. The turbine building was dynamically analyzed and designed to accommodate an SSE event.

2.1 Building Description and Structural Systems The Turbine Building houses the turbine generator unit and its attendant auxiliary equipment, including condensers, interconnecting piping and valves. The building enclosure consists of exterior walls of reinforced concrete to Elevation 102 feet. Except where shielding is required, the enclosure above Elevation 102 feet is accomplished with precast concrete panels to Elevation 125 feet 6 inches and with insulated metal siding from Elevation 125 feet 6 inches to the roof. The roof has a nominal Elevation of 200 feet and consists of cellular metal decking, insulating board, and built-up roofing material.

Vertical loads are supported by reinforced concrete walls and structural steel columns.

Generally, interior reinforced concrete walls and structural steel columns extend from the top of the base mat to Elevation 137 feet.

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2. Turbine Building

, I L l Floor slabs are reinforced concrete supported by structural steel framing. They are i designed to act as diaphragms to resist lateral loads and transfer them to the shear walls. The reinforced concrete thear walls transfer the lateral loads to the reinforced concrete foundation mat.

, in the turbine generator bay, structural steel rigid frames spanning the east-west direction support roof loads, east-west lateral loads, and crane loads. North-south lateral loading is generally resisted by steel bracing and transferred into the shear walls

! at elevation 137 feet.

, I l 2.2 Seismic Design Basis l

The Turbine Building is a non-Seismic Category I structures designed to maintain elastic j behavior for the loads and load combinations described in Table 2-1 below, in addition, I the Turbine Building is checked to verify that it does not collapse on, or interact with, adjacent Seismic Category I structures for certain abnormal and extreme environmental conditions, as described in Table 2-2 below. All reinforced concrete components of the structure are designed by the strength method per ACI 318, as listed in Table 2-1.

Structural steel components are designed by the working stress method per AISC specifications listed in Table 2-1.

l The Turbine Building is designed in accordance with the criteria established by the UBC, as listed in Table 2-1, for structures in Seismic Zone No.1. 4 To provide assurance that the turbine building will not collapse due to SSE ground motions, it is analyzed using dynamic techniques. This structure is designed to accommodate an SSE event by the following methods:

1. Reinforced concrete elements are designed for ductile behavior in accordance with UBC or for elastic-plastic behavior provided its ductility factor does not exceed 3 and structural resistance is based on Section Strength (U) for concrete.

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2. Turbine Building

2. Structural steel elements are designed by the working stress method or for elastic plastic behavior provided its ductility factor does not exceed 3.

3. Concrete masonry unit walls in the non-Seismic Category I turbine building is used only for radiation shielding, fire separation, and ,

miscellaneous supports, and are designed for verticalloading and seismic loading in accordance with the UBC, as listed in Table 2-1.

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2. Turbine Building Table 2-1 (a)

DESIGN LOADING COMBINATIONS LOAD COMBINATIONS FOR REINFORCEC CONCRETE NON-SEISMIC CATEGORY I STRUCTURES

1. U = 1.4D + 1.7 L

2. U = 0.75 (1.4 D + 1.7 L + 1.87 Eu) + 1.0 Ro (2)

3. U = 0.75 (1.4 D + 1.7 L + 1.7 W) + 1.0 Ro (2)

4. U = 0.9 D + 1.3 W + 1.0 Ro

5. U = 0.9 D + 1.43 Eu + 1.0 Ro (2)

In addition to the requirements above, the structures are checked to verify that they do not collapse on, or interact with, adjacent Seismic Category I structures for the following load combinations under abnormal and/or extreme environmental conditions:

6. U = D + Lo + Es + To + Ro (2)

7. U = D + L + We + To + R (2)

8. U = D + L + We + To + Ro (2) l

9. U = D + L + Ra + 1.5 Pa + Ta (2)

10. U = D + Lo + Ra + Rr + Pa + Es + Ta (1) The Turbine Building and the administration facility.

(2) Ro' which produces the most critical combination loading, is used.

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2. Turbine Building l

l Table 2-1 (b)

DESIGN LOADING COMBINATIONS l LOAD COMBINATIONS FOR STRUCTURAL STEEL AND CONCRETE MASONRY NON-SEISMIC CATEGORY I STHUCTURES(1)

S=D+L 1.33S = D + L + E + Ro (2) 1.33S = D + L + W + Ro (2)(3)

S = D + Lo + Eu + Ro (2)(3) j i

l In addition to the requirements above, the structures are checked to verify that they do not collapse on, or interact with, adjacent Seismic Category I structures for the'following load combinations for structural steel structures under abnormal and/or extreme environmental conditions:

1.5S = D + Lo+ To + Ro (2) 1.6S = D + Lo+ Es + To + Ro (2) 1.6S = D + L + Wt + To + Ro 1.6S = D + L + Wo + To + Ro (2) 1.6S = D + L + Ra+ Pa + Ta 1.7S = D + Lo + R3 + Rr + Pa + Es + Ta (1) The Turbine Building and the administration facility.

(2) Ro which produces the most critical combination of loading, is used.

(3) This load case is used only for structural elements carrying mainly earthquake forces, e.g., struts and bracings.

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l DESIGN CODES i l

The turbine building was designed using the following general codes, standards, and I recommendations:

a. American Institute of Steel Construction (AISC) Specification for the i Design, Fabrication, and Erection of Structural Steel for Buildings,1969 with Supplement 1 November 1,1970, Supplement 2 of December 8,  !

1971 and Supplement 3 of June 12,1974. ,  ;

b. American Concrete Institute (ACl) Building Code Requirements for Reinforced Concrete, ACI 318,1971 with 1974 Supplement including 1973 and 1974 revisions,

c. American Concrete Institute (ACl) Building Code Requirements for i

, Concrete Masonry Structures, ACI 531,1979.

d. American Welding Society (AWS) Structural Welding Code AWS D1.1, 1975

e. Portland Cement Association Design of Multistory Reinforced Concrete Buildinga for Earthquake Motions, J.A. Blume, N.M. Newmark, and L.H.

Corning,1961.

f. International Conference of Building Officials, Uniform Building Code, 1973.

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3. Turbine Condenser The High Pressure condenser has a heat transfer surface area of 273,810 ft2 . In Table 3-1, the design attributes of the condenser is compared with the two sites in the earthquake experience database that have condensers most representative of BWR type condensers: Moss Landing Units 6 & 7, and Ormond Beach Units 1 & 2.

The shell of the condenser is constructed of 7/8" thick ASTM A-285 Gr. C steel. The database condenser shells are 3/4" thick ASTM A-285 Gr. C steel. The overall heat transfer area, weight, and footprint of the condenser are generally enveloped by the database condensers, as shown in Figures 3-1,3-2, and 3-3. Specific details of the Hope Creek condenser design which were compared with those given in NEDC-31858P are given in Section 3.1.

In summary, the condenser design and anchorage are similar to those at facilities in the earthquake experience database that have experienced earthquakes in excess of the Hope Creek design basis SSE (See Figure 41). Appendix D, Section 4.1, of NEDC - 31858P contains details of the earthquake experience for condensers.

3.1 Hope Creek Condenser Design Basis Design Code Heat Exchanger institute (HEI) Standards Hydrostatic Test Requirements Shell- Completely filled with water P:\200235.01Pasiv. Doc 3-1 W

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3. Twbine Condenser Manufacturer Southwestern Engineering I

Surface Area, Wcight, Dimensions Surface Area: condenser has 273,810 ft2 l l

Weight: condenser weighs 1,059,400 lbs empty,2,200,800 operating and 4,487,700 lbs flooded.

Dimensions: condenser is 39'-2" long,29'-0" wide and 57' high.

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Base supported, rectangular, double pass. l l

ShellMaterial and Thickness i

Material: ASTM A-285 Gr. O steel  !

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Thickness: 7/8" Tube / Sheet Design Material: Aluminum Bronze, ASTM B-171 Alloy 614 Thickness: 1-1/4" Tubes: Are of titanium, are 7/8"in outside diameter,22 BWG. The effective tube length j is 40', 1 Support Plate Spacing: There are (16) tube support plates. This results in a support I spacing of about 26" to 30".

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3. Tuvbine Condenser Hotwell Capacity The hotwell storage capacity is 20,700 CU. FT.

3.2 Anchorage The Hope Creek condenser anchorage is shown schematically in Figure 3-4. The condenser has six sliding plate supports with (4) 2" diameter A36 anchor bolts each.

Each anchor bolt has 3'-0" embedment in the turbine building foundation. The center anchor support, (4 - 2 %" anchor bolts) resists lateral loads in the both directions. The supports are designed to resist operating loads. Thermal growth of the condenser occurs from a fixed point at the center of the base. The sliding plate supports have oversized or slotted holes allowing thermal growth in specified directions. The slots and oversized holes sized so that the anchor bolts may bear against the anchor plates in the hot condition.

An evaluation of the condenser support system was performed. Seismic demand was developed, corresponding to Standard Review Plan (SRP) guidance, for the turbine building at the condenser foundation elevation. A 5% critical damped response spectra at the condenser foundation was used in the condenser anchorage analysis. The existing condenser anchorage system was determined to have adequate capacity (combined shear and tension interaction <1) to withstand the combined operational and lateral seismic forces which could occur during an SSE event.

The condenser anchorage was compared with the performance of similar condensers in the earthquake experience database. The shear area of the condenser anchorages, divided by the seismic demand was used to compare condenser anchorage with condensers in the earthquake experience database (See Figures 3-5 and 3-6).

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3. Turbine Condenser i

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} l 2,200,800 Hope Creek l i

i Ormond Beach 1,767.500 I

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j Mosa Landing 3.115,000 i

j 0 500,000 1,000,000 1,500,000 2,000,000 2,500.000 3.000,000 3,500,000 j Weight (ts) 1 1

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Hope Creek 273,810 Ormond Beach 210,000 Moss Landng 435 000 0 50.000 100,000 150.000 200,000 250,000 SJ0,000 350,000 400.000 450,000 i

j mat Transbr Area (t2) i 4

i j Figure 3-1: Size comparison of Hope Creek condenser with database condenser 1

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3. Turbine Condenser l

l Comparison of Hope Creek Condenser with Database Condensers l

l Hope Oeek 57 I Ormond Beach 20 Moss Landing 47 0 10 20 30 40 50 60 Height (feet) l l

Figure 3-2: Comparison of Hope Creek condenser with database condensers h:uoo235.01Hemsiv. Doc 3-5

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Figure 3-3: Comparison of Hope Creek condenser plan dimensions with database condensers P;\200235.01Hemsiv. Doc 3-6

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3. Turbine Condenser f

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. . Fixed anchor Plate Figure 3 4: schematic plan view of Hope Creek condenser anchorage PM00235.01ticmsiv. Doc 3-7

3. Turbine Condenser 1

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I 0.0002 Resistance to Seismic Demand 2  :

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• Landing Creek j Condenser anchorage to demand for parallel to turbine generator axis Note 1: Shear Area (in2)/ Demand (condenser weight x g level) -

Figure 3-5: Comparison of Hope Creek condenser anchorage with database j condensers j E 0.0002 E

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3 Lower Bound 1 0 i j Moss O Centro Hope Creek Landing j 1

Condenser anchorage to demand for transwrbe to turbine generator axis j Note 1: Shear Area (in2)/ Demand (condenser weight x g level) l Figure 3-6: Comparison of Hope Creek condenser anchorage with database l condensers l P:\200235.01\ Hems!v. Doc 3-8 (h

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4. MSIV Leakage Control Piping The piping relied upon to establish an Alternate Treatment Pathway includes both seismically analyzed and non-seismically designed systems. Analyzed lines included the Main Steam Line (from the MSIV to the turbine stop valve) and portions of various main steam branch lines to the isolation valves for the branch. Analysis methods for these lines are seismic Category I qualification methods for Hope Creek and design capacities are expected to be adequate to assure good seismic performance.

l Portions of main steam drain system piping that have not been seismically analyzed were reviewed to demonstrate that piping and supports fall within the bounds of design characteristics found in selected conventional power plant steam piping. These l conventional power plant steam piping designs demonstrated good seistnic  ;

performance and were shown to be comparable to the piping designs for Hope Creek.

First a review of the design codes and standards was performed to demonstrate that the attemate drain path piping was built to standards similar to those plants identified in the

" Experience Database". Second a " Seismic Walkdown" was performed by EOE engineers, experienced in the development of the " Earthquake Database", to insure that

! the Alternate Darin Path piping design details are consistent with those good perforrning designs described in NEDC-31858P. Seismic issues identified in the walkdown

(" outliers") were evaluated and resolved as shown in Table 41.

The non-seismic portion of the Alternate Drain Path to the condenser was designed to the 83.1.1 code. This line was seismically analyzed to demonstrate that adequate strength and design capacity exist for piping components and support designs. The Alternate Leakage drain piping and supports were demonstrated to have adequate capacity for an SSE seismic event.

In summary, the piping for the main steam line was seismically analyzed and designed in accordance with Hope Creek seismic Category I qualification methods. The Alternate Drain Path and associated piping have been demonstrated to be similar to the piping P:\200235.01\Hcmsiv. Doc 4-1 I

4. MSIV Leakage Control Piping found in commercial piping systems in the earthquake experience data base that have experienced earthquakes in excess of the Hope Creek design bases earthquake. These evaluations provide reasonable assurance that the Attemate Drain Pathway piping system and its supports will perform their intended function under normal and seismic loadings.

l 4.1 Main Steam Piping Main steam piping systems performance in the earthquake experience database have experienced no failures as reported in NEDC-31858P.

The Hope Creek Main Steam system was designed in accordance with the ASME Code Section 111 Class 2 and 3 requirements using Category I seismic design analysis techniques. The analysis models the main ste-am piping up to the turbine stop / control valves and branch piping up to seismic anchors beyond valves HV F029, HV-F033, HV F072 HV-F073 and HV-F026.

Design margins in these systems are those inherent by application of the ASME and seismic design methods.

4.2 Non-Seismic Piping Evaluation A Hope Creek plant specific seismic verification walkdown of all piping associated with I the MSIV Alternate Leakage Treatment Path was performed by qualified seismic engineers. The seismic engineers were experienced in the development of the

" Earthquake Database" for piping. The purpose of the walkdown was to physically verify that the piping and components in the Attemate Leakage Treatment Path have attributes similar to those in the database that have good seismic performance and to )

l identify potential seismic vulnerabilities. As a result of the walkdown and subsequent evaluations it was determined that the plant features compare well with the database.

f I l 1 1

I PA200235.01Hemsiv. Doc 4-2 l' l l

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4. MSIV Leakage Contvol Piping l

4

" Earthquake Database" Representation of Piping Earthquake experience piping data from the El Centro Steam Plant, the Valley Steam  !

Plant, PALCO Co-generation Plant, Cool Water Plant, and Bulk Mail facilities affected by the 1987 Whittier Earthquake were selected for presentation and comparison of various piping design parameters and attributes. The El Centro Steam and Valley Steam Plants affected by earlier earthquakes were selected for parametric studies because substantial documentation on the earthquake input and piping configuration is available. i i

Support spans for small bore piping systems were compiled from field investigations and/or design documents at the above database facilities. These spans represent the distance between horizontal or vertical supports for piping runs or the distance to the first horizontal and vertical support from nozzles or tees. These spans represent a diversity of pipe runs which have performed successfully during earthquakes. '

A comparison between the Hope Creek Piping in the Alternate Leakage Treatment Path and the pertinent database piping is provided. The comparison is specific for each of  ;

the pipe diameters at Hope Creek, its associated pipe thickness, and associated pipe diameter to-thickness ratio. l Table 4-2 shows the pipe diameters, wall thickness and pipe diameter-to thickness (D/t) ratios for the Hope Creek Alternate Leakage Treatment Path piping. l Table 4-3 shows the pipe diameters, wall thickness and pipe diameter-to thickness (D/t)

ratios for piping at selected database power plant facilities. Additional data on piping in the seismic experience database has been submitted to the NRC in the following documents

l m NEDIC-31858P, Rev. 2: "BWOG Report for increasing MSIV Leakage Rate Limits and Elimination of Leakage Control Systems".

l m " Supplemental Piping Earthquake Performance Data".

The information in Table 4-3 is a sampling of main steam piping and process piping at selected power plants in the seismic experience database. This represents a small P:\200235.01\Hcmsiv. ooc 4-3 (h

. . . . . - _ . , _ _ . . _ . _ . _ _ _ _ . ._.-_.___._._._____.._.m.__._.-_.

4. MSIV Leabge Control Piping l portion of the facilities with power and petrochemical piping which have been studied for the effects of strong motion earthquakes. The range in piping parameters from Tabies 4-2 and 4-3 is summarized in Table 4-4 an' d Figure 4-2. Table 4-4and Figure 4-2 demonstrate that the Hope Creek alternate treatment path piping is represented within database piping.

p 4.3 . Comparison of Hope Creek Design SSE Spectra with the Earthquake p - Database Plants L The Hope Creek design basis SSE ground response spectrum was compared with the ground motion spectra at several database power plant sites in the attached Figure.-4-1.

From a review of Figure 4-1, the database spectra is seen to significantly envelop the -

Hope Creek spectrum over the entire frequency range of interest. -

Comparison of ground spectra as the basis for representing seismic capacity vs.

l demand for piping and equipment components is consistent with the methods

- established in the SQUG program for resolution of USI-A46.

Therefore, comparison of the Hope Creek design basis ground spectrum with the earthquake database sites provides conservative justification that the floor motions that excite the Hope Creek piping are bounded by the floor motions experienced by the database site piping.

4.4 Alternate Drain Path Seismic Analysis The main non-scismic designed portion of the Alternate Leakage Treatment drain path l to the condenser was seismically analyzed to demonstrate that adequate strength and seismic capacity exist for piping components and support designs. The analysis was performed using a dynamic finite element computer model.

Load cases analyzed included thermal, pressure, gravity, seismic SSE and seismic anchor movements at building interfaces. Response spectra used in the analysis was L the envelope of 5% critical damped design spectra for the turbine and auxiliary buildings {

i  :

l

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c PA200235.01Ncmsiv. Doc 4-4 (i

4. MSIV Leakage Control Piping  !

l  ;

I at elevation 137 feet. Pipe stress for seismic and sustained loads were limited to 2.4Sh-The maximum pipe stress ratio calculated was 0.89.  !

l Pipe supports for the system were evaluated using the Conservative Deterministic

)

Failure Margin (CDFM) Methodology from EPRI Report NP-6041-SC using support loads generated from the piping system seismic analysis. Component support and anchorages were evaluated.

The maximum pipe support component stress ratio calculated was 0.74. All support anchoraaes have adequate capacities. l 1

P:\200235.01\Homsiv. Doc 4-5

4. MSIVIrakage CorJrol Piping Table 4-1 HOPE CREEK MSIV WALKDOWN OUTLIERS

SUMMARY

SHEET System Description ID Outiier A F P D V Resolution Main Steam- Drain Path RB Portion HV-F072 1 Conformance to screening X Resolved by further evaluation. Acceptable as-is.

criteria HV-F069 2 Confornunce to screening X Resolved by further evaluation. Acceptable as-is.

cnteria HV-F033 3 Conformance to screening X Resolved by further evaluation. Acceptable as-is.

criteria HPCl/RCIC Steam Supply Drains Strainer ST-D003 4 Strainer motion may damage X Modified per DCR# 4HE--0279 P i Pe MS Lines-MSIV to isolation Valves HV-F028 A to D 5 Extended Valve Operators X These are Seismic Category I (O Class) valves and are seismically qualified.

HV-F3631 A to D 6 Valve function is required X These are Seismic Category I (O Class) valves and are seismically qualified.

Condenser 7 Evaluate anchorage X Resolved by further evaluation. Acceptable as-is.

Key to issues:

A Anchorage or Support Capacity D Differential Displacement F Failure and Falling (11/I) V Valve Screening P Proximity and Impact M

@)

s P.\200235.01\Hcmsiv. Doc 4-6

Table 4-2 i

HOPE CREEK ALTERNATE DRAIN PATH PIPING DESIGN PARAMETERS Pipe Wall Pipe Size O.D. Thickness System (NPS) (inch) Schedule (inch) Dh l

Hope Creek 4 4.500 120 0.4370 10.30 l Me!n Steam Drains, 3 3.500 80 0.3000 11.67 1

Vants & Branches 2 2.375 160 0.3430 6.92 I l

1 1.315 80 0.1790 7.35 l

)

1 P:\200235.01\Hcmsiv. Doc 4-7

l

4. MSIV Exakage Control Piping l I

Table 4-3 EARTHQUAKE EXPERIENCE DATABASE PIPING DESIGN PARAMETERS 1

Pipe i Pipe Size O.D. Wall Thickness l Facility (NPS) (inch) Schedule (inch) D/t 4 4.5 160 0.531 8 4 4.5 40 0.237 19 3 3.5 160 0.437 8 3 3.5 80 0.300 12 Valley Steam Plant l Units 1 & 2 3 3.5 40 0.216 16 2 2.375 160 0.343. . 7 2 2.375 40 0.154 15 1% 1.9 160 0.281 7 ,

1% 1.9 40 0.145 13 1 1.315 40 0.133 10

% 1.05 160 0.218 5

% 1.05 40 0.113 9 4 4.5 80 0.337 13 4 4.5 40 0.237 19 3 3.5 160 0.437 8 3 3.5 80 0.300 12 El Centro Steam Plant 3 3.5 40 0.216 16 2 2.375 160 0.343 7 2 2.375 80 0.218 11 2 2.375 40 0.154 15 1% 1.9 160 0.281 7 1% 1.9 80 0.200 10 1% 1.9 40 0.145 13 1 1.315 80 0.179 7 1 1.315 40 0.133 10 1

P;\200235.01\Hemsiv. Doc 4-8 W

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4. MSIV lxakage Control Piping j i

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i Table 4-4 COMPARISON OF HOPE CREEK PIPING DESIGN PARAMETERS WITH EARTHQUAKE EXPERIENCE DATABASE PlPING DESIGN PARAMETERS l

Parameter Hope Creek Database Sites Diameter (inch) 1.0 - 4.0 1.0 - 4.0 Wall thickness (inch) 0.175 - 0.4370 0.133-0.531 I Diameter-to-Thickness Ratio 7-10 7 -19.0 i

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t I

I l

I l

I 1

P:\200235.01\Hemsiv. Doc 4-9 l

l I

4. MSIV Linkage Control Piping 1.4 ----------------------------------i--------- .

---

-------i--------------- --------- ------- -- .

32 ......................................:.......... .... . . ...:... .... ..:.....................................

. . . -e-Hope Creek SSE

.i d 6 .i

-e- Moss Landing

VaBey Steam 1 --------------------------- ---- ------------- - -

- -.--- - .--------- -------------- ------------- -*- El Centro m i .

. i  : Coolwater o p ee j-L -

... .. Bulk 23 Rb Dd 3 0.8 ------------ - --------------------- ------ - ---- ----- -- --- - ------ --- ------------------- ------

8  :  :

Humbot *75(1) 7a-

~

a Humbolt '80(1) j i 'i -a Humbolt '92(1) a 06 ----------------------~~ ---- ---- a-- - 4,- -- - -

- :o* ----------- - - ---- - ---- - --- -a u) . f Gendale(1) 0.4

---

-- -- ------ - --- ---~~----------------------- --- o ---------------- ----

.r o Note (1k

• 2pa values 02 -------------- - ----- -- -- -A:4.--- - ----- --------- ----------

---

t----- - ---- -- ----------------

0 O.1 1 Frequercy to 100 Figure 4-1: Comparison of Earthquake database sites and Hope Creek SSE spectra PA200235.01\Hcmsiv. Doc 4-10 t

4. MSIV hakage Control Piping i

i E Database Piping l O Hope Creek Piping  ;

j (Excluding Seismically Qualified D/t Main Steam and Turbine Bypass) 20 -- 3, 16

'8 15 -- -

10 --

4 8 8

7 7 7

5- -

5 i

l 0 l l l 1 i 1 2 3 4

}

j Pipe Size (NPS) 1 Figure 4-2: D/t rations for Hope Creek alternate drain path piping and selected database piping I

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PM00235.01W1cmsiv. Doc 4-11 E i

l D cum:nt C:ntral D: k LR-N98564 l Attachm:nt 5 LCR H98-10 l

l HOPE CREEK GENERATING STATION l FACILITY OPERATING LICENSE NPF-57 DOCKET NO. 50-354 REVISIONS TO THE TECHNICAL SPECIFICATIONS (TS)

APPLICATION FOR REVISED EXEMPTION TO APPENDIX J OF 10CFR50 l Pursuant to 10CFR50.12(a), PSE&G, holder of Facility Operating License No. NPF-57, i hereby requests revisions to the basis for existing exemptions to Appendix J of 10CFR Part 50 " Primary Reactor Containment Leakage Testing For Water-Cooled Power Reactors" In conjunction with this application for exemption request, PSE&G is transmitting to the Nuclear Regulatory Commission an application, contained in Attachments 1-4 of this letter, for a license amendment pursuant to 10CFR50.90. The license amendment request involves a proposed change to Section 3.6.1.2 of the Technical Specifications to permit an increase in the allowable leak rate for the MSIVs from the current 46.0 total standard cubic feet per hour (scfh) to 200 scfh per main steam line (and 400 scfh  !

combined for all four main steam lines), and a proposed change to Section 3.6.1.4 for eliminating the requirements for the current MSIV Sealing System. The safety analysis I has been revised to assess the radiological effects of MSIV leakage following a postulated design basis LOCA. In Attachment 3 of this letter, PSE&G has  ;

demonstrated that the proposed change does not involve a significant hazards I consideration. l This proposed exemption is a result of the extensive work performed by the BWR Owners' Group (BWROG) in support of the resolution of Generic Issue C-8 "MSIV Leakage and Leakage Control System (LCS) Failure". The following discussion provides a detailed justification and evaluation of the proposed exemption. The proposed exemption is found to be authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security.

Furthermore, special circumstances are present that warrant the granting of this exemption.

The proposed exemption will not cause additional operational activities that may significantly affect the environment. It does not result in a significant increase in any adverse environmental impact previously evaluated, result in a significant change in effluents or power levels, or affect any matter not previously reviewed by the Nuclear Regulatory Commission that may have a significant adverse environmental impact.

Therefore, pursuant to 10CFR50.12(a), PSE&G hereby requests a revision to the basis I

l Page 1 of 8

Drcum:nt C:ntral D=k LR-N98564 Attachm:nt 5 LCR H98-10 I for existing exemptions for the Hope Creek Generating Station (HCGS) for MSIV testing from the test criteria specified in Appendix J of 10CFR50.

l A. Justification l The regulation of 10CFR50, Appendix J, Paragraphs Ill.A.5(b)(1) requires the overall integrated leakage rate, as measured during containment pressure tests (Type A), to l meet the acceptance criterion of less than or equal to 0.75 of the maximum allowable I containment leak rate. As described in the Bases Sections B 3/4.6.1.2 of the Technical  !

Specifications, the limitations on primary containment leakage rates ensure that the I total containment leakage volume will not exceed the value assumed in the accident i analyses at the peak accident pressure.

The maximum containment leakage rate was included in the radiological analysis of a postulated design basis LOCA as evaluated in Section 15.6.5 of the Final Safety Analysis Report (FSAR). The radiological analysis calculated the effect of the maximum leakage rate from the containment volume in terms of control room and off-site doses, which were evaluated against the dose guidelines of 10CFR50, Appendix A (General Design Criteria 19) and 10CFR100, respectively. Leakages from the containment volume were contained in the reactor building (secondary containment),

l filtered by the Filtration, Recirculation and Ventilation System (FRVS), and then released to the environment. The maximum containment leakage rate includes leakages through structures, all penetrations identified as Type B, and all containment isolation valves identified as Type C.

Hope Creek has already received exemptions from 10CFR50, Appendix J requirements based upon the NRC conclusion that the Hope Creek MSIV leak testing methods were acceptable alternatives to the requirements. This conclusion was included in the Hope Creek Safety Evaluation Report (SER)(i.e., NUREG-1048, and its supplement 5). In part, the NRC granted exemptions to: 1) exclude MSIV leakage results from the combined leakage for the local leak rate tests (Types B and C) (as required by 10CFR50, Appendix J, Sections ll.H, Ill.C.3); and 2) leak test MSIVs at a pressure of 5 psig instead of 1.10 Pa (as required by10CFR50, Appendix J, Section Ill.C.2). These exemptions were granted for Hope Creek based, in part, upon: 1) the acceptable l results from separate accounting of MSIV leakage in the plant's LOCA dose assessments; 2) the undue hardship that would be caused in leak testing MSIVs at l pressures greater than 5 psig; and 3) the acceptable methods for utilizing a correction factor for determining leakage rates at the 5 psig test pressure.

PSE&G is requesting no changes to the above exemptions granted for Hope Creek; however, as contained in Attachments 1-4 of this letter, PSE&G, pursuant to Page 2 of 8 7

i Decumtnt Centrol Duk LR-N98564 i j- Attachmtnt 5 LCR H98-10 10CFR50.90, is requesting a license amendment to permit an increase in the allowable i leak rate for the MSIVs from the current 46.0 total standard cubic feet per hour (scfh) to l l 200 scfh per main steam line (and 400 scfh combined for all four main steam lines), and l a proposed change to Section 3.6.1.4 for eliminating the requirements for the current L MSIV Sealing System. Therefore, the description of the MSIV Sealing System and the l

assumed MSIV leak rate will no longer be accurate once the proposed modification is i performed and the implementing Technical Specification change is approved. As a result, the basis for the current exemptions is only being revised to justify the increased allowable MSIV leakage rate and reflect the deletion of the MSIV Sealing System as i described in the following paragraphs.

The LOCA dose analyses have been revised to account for the radiological effect from MSIV leakages and from those of other containment leakages following a postulated design basis LOCA. Unlike the treatment path for other containment leakages, the treatment of MSIV leakages employs the main steam drain piping and the condenser.

Fission products are removed by plate-out and hold-up in the relatively large volumes of

)

the main steam piping and condenser. The treatment method for MSIV leakages is

! recommended by the BWROG in support of the resolution to Generic issue C-8, and the proposed changes are based on the General Electric (GE) report prepared for the ,

Boiling Water Reactor Owners' Group (BWROG), "BWROG Report for increasing MSIV l Leakage Rate Limits and Elimination of Leakage Control System," NEDC-31858P, Revision 2, submitted to the NRC by BWROG letter dated October 4,1993. '

The BWROG has evaluated the availability.of main steam system piping and condenser alternate treatment pathways for processing MSIV leakage, and has determined that the probability of a near coincident LOCA and a seismic event is much smaller than for other plant safety risks. The BWROG has also determined that main steam piping and condenser designs are extremely rugged, and that the ANSI-B31.1 design requirements typically used for nuclear plant system design contain a good deal of margin.

l-In order to furtherjustify the capability of the main steam piping and condenser alternate treatment pathway, the BWROG has reviewed limited earthquake experience

~

data on the performance of non-seismically designed piping and condensers (in past earthquakes). This study concluded the possibility of a failure which could cause a loss of steam or condensate in BWR main steam piping or condensers in the event of a design basis earthquake is highly unlikely, and that such a failure would also be contrary to a large body of historical earthquake experience data, and thus l - unprecedented. As indicated in Attachment 4 of this submittal, Hope Creek specific l seismic analyses of the proposed MSIV leakage treatment pathway have been i

Page 3 of 8 i

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!s Docum:nt Centr:I Deck LR-N98564 Attachm:nt 5 LCR H98-10 performed, which conclude that the MSIV leakage treatment pathway will function per

- the design requirements of NEDC-31858P during and following an SSE.

MSIV leakage still should w @ included in the Type A acceptance criterion because the treatment path for MSIV hakage is different from that of containment leakage.

Potential leakage from the containment is contained in the reactor building (secondary i containment), treated by the FRVS and released to the environment. MSIV leakage, on '

the other hand, is contained, plated-out, and delayed in the main steam pipira and the condenser, and released via the turbine building.

The deletion of the MSIV Sealing System is proposed partly in response to the safoty ,

concern identified by Generic issue C-8 that the MSIV Sealing System would not function at high MSIV leakage rates since the process capability of the system at Hope Creek is designed for MSIV leakage rate of no more than 100 scfh. MSIV leakage is treated separately from other cc:dainment leakages, and therefore any exemption that was previously granted in accordance with Section Ill.C.3 of Appendix J of 10CFR50 should remain applicable.

l As discussed earlier, the basis for the containment leakage tests and the acceptance criteria is to ensure that the measured leak rate will not exceed the maximum leak rate assumed in the safety analysis. The safety analysis for a design basis LOCA has been revised to include the maximum MSIV leak rate separately from the maximum containment leak rate. MSIV leakages will be tested as part of the local leak rate test in accordance with the requirements contained in Technical Specification 3.6.1.2. This test ensures that the measured MSIV leak rate will not exceed the allowable leak rate l- assumed in the safety analysis. The MSIVs will be tested by pressurizing the volume i

between the inboard and outboard MSIVs to 5 psig and measuring the corresponding  !

- leakage rate.- As already permitted by the Hope Creek exemption to Appendix J requirements, the same correction factor methodology will be used to determine the MSIV leakage rates up to 48.1 psig (1 Pa) (as is required by 10CFR50, Appendix J, Section Ill.C.2.a). There is sufficient conservatism in the maximum allowable MSIV leak rate to account for possible degradation of the MSIV leakage barrier between leakage tests. As discussed in the application for the license amendment, PSE&G l proposes a maximum allowable MSIV leak rate of 200 scfh per main steam line; l whereas radiological analyses performed for Hope Creek demonstrate that total MSIV  !

leakage of all four lines up to 800 scfh will not result in dose exposures in excess of the l regulatory limits. Thus, a safety margin exists. Furthermore, PSE&G willimplement  !

into the MSIV maintenance and test program, as well as into the Technical I Specifications, a requirement stating that any MSIV exceeding the proposed 200 scfh L limit, will be repaired and re-tested to meet a leakage rate of less than or equal to 11.5 4

i i Page 4 of 8

i D:cumsnt Central Drgk LR-N98564 Attachm:nt 5 LCR H98-10 l scfh. This will assure continuation of high quality repair and refurbishment efforts to improve the overall performance and reliability of the MSIVs.

i Therefore, the proposed exemption from the acceptance criteria of 10CFR50, Appendix J, will not defeat the underlying purpose of the regulation, and is consistent with the safety analysis.

! B. Authorized By Law l

l The NRC may, upon application, grant exemptions from the requirements of 10CFR50 L where special circumstances are present. The requirements of 10CR50.12(a)(2)(ii)  !

j state that the NRC may grant exemptions from the requirements of 10CFR50 whenever

]

l the application of the regulation in the particular circumstances would not serve the '

i underlying purpose of the rule or is not necessary to achieve the underlying purpose of l the rule. PSE&G has concluded thatf 1) the current MSIV leak rate testing method (i.e., test pressure of 5 psig when applied between MSIVs)is an acceptable method; and 2) the proposed alternate MSIV leakage pathway, and the calculated doses l

obtained by performing a radiological analysis, which assumed an MSIV leakage rate limit.of 200 scfh per steam line, not to exceed 400 scfh for all four steam lines, are l within the limits of 10CFR100 and General Design Criteria 19. Therefore it is

! acceptable to continue to exclude the measure MSIV leakage rate from the combined i local leak rate, since the leakage is accounted for separately and continues to meet the underlying purpose of the rule. Such an exemption was granted to the Limerick Generating Station on February 16,1995.

C. No Undue Risk to Public Health and Safety i The proposed exemption presents no undue risk to public health and safety. The i revised MSIV leakage rate has been incorporated in the radiological analysis for a  !

postulated LOCA as an addition to the designed containment leak rate. The analysis  !

! demonstrates an acceptable increase to the dose exposures previously calculated for l the control room and off-site. The revised LOCA doses remain well within the  :

guidelines of 10CFR100 for off-site doses and 10CFR50, Appendix A, (General Design ,

l Criterion 10) for the control room doses. Potential MSIV leakage is subjected to plate- i out, and hold-up in the main steam piping and condenser, thus minimizing their effect on the total dose released. As discussed in Paragraph F of this Attachment, the proposed change will not adversely affect the conclusions of the previously issued l Hope Creek Safety Evaluation Report (NUREG-1048). Therefore, the proposed l

exemption presents no undue risk to public health and safety.

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D

cum:nt Contral D::k LR-N98564 Attachmsnt 5 LCR H98-10 l

D. Consistent with Common Defense and Security With regard to the " common defense and security" standard, the granting of the requested exemption is consistent with the common defense and security of the United States. The Commission's Statement of Considerations in support of the exemption rule note with approval the explanation of this standard as set forth in Long Island Lighting Company (Shoreham Nuclear Power Station, Unit 1), LBP-84-45,20 NRC 1343,1400 (October 29,1984). There, the term " common defense and security" refers principally to the safeguarding of special nuclear material, the absence of foreign

control over the applicant, the protection of Restricted Data, and the availability of special nuclear material for defense needs. The granting of the requested exemption will not affect any of these matters and, thus, such grants are consistent with the common defense and security.

E. Special Circumstances Are Present Special circumstances are present which warrant issuance of this requested exemption.

These special ciret ,istances are riscussed in accordance with the classification contained in 10CFR50.12(a)(2):

i i. Application of the regulation in the particular circumstances 'would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule.

The underlying purpose of the rule is to limit releases to within the off-site and control room dose guidelines of 10CFR100 and 10CFR50, Appendix A, General Design Criterion 19, respectively. Compliance with Appendix J of 10CFR50 Type A test acceptance criteria is not necessary to achieve the underlying purpose of the rule since MSIV leakage is not directed into the reactor primary containment. Instead, the MSIVs leakage is directed through the main steam drain piping into the condenser. Since

- Type A tests are intended to measure the primary containment overall integrated leak rate (ILRT), the MSIVs leakage rate should not be included in the measurement of the ILRT.

As indicated in Attachment 5, analyses has been revised to assess the radiological consequences of MSIV leakage following a design basis LOCA. The analysis has demonstrated that the revised LOCA doses are well within the off-site and control room dose guidelines of 10CFR100 and General Design Criter'an 19. ,

l l ii. Compliance would result in undue hardship or other costs that are significantly in excess of those contemplated when the regulation was

Page 6 of 8 i l

Dscum:nt Centrcl D=k LR-N98564 Attachm:nt 5  !.CR H98-10 t

l

adopted, or that are significantly in excess of those incurred by others  ;

similarly situated. l l

Compliance with Appendix J of 10CFR50 Type A test acceptance criteria results in j undue hardship or other costs that are significantly in excess of those contemplated l

! when the regulation was adopted. The proposed increase in the MSIV allowable leak l

rate will not be possible if the MSIV leak rate results are included in the Type A test l acceptance criteria. I l

Compliance requires unnecessary repair and re-testing of the MSIVs. This significantly impacts the maintenance work load during plant outages and often contributes to outage extensions. The frequent MSIV disassembly and refurbishing, which is required to meet the low leakage limits, contributes to repeated failures. Examples of these maintenance induced defects include machining-induced seat cracking, machining of guide ribs, excessive pilot valve seat machining, and mechanical defects induced by assembly and disassembly. By not having to disassemble the valves and refurbish them for minor leakage, HCGS avoids introducing one of the root causes of recurring leakage. Industrial experience suggests that, by attempting to correct non-existing or minimal defects in the valves, it is likeh that some actual defects may be introduced that lead to later leak test failures.

In addition, the frequent maintenance work results in needless dose exposures to maintenance personnel leading to additional economical burdens, and are inconsistent with As Low As Reasonably Achievable (ALARA) principles.

iv. The exemption would result in benefit to the public health and safety that compensates for any decrease in safety that may result from the granting of the exemption.

Via Attachments 1 through 4 of this letter, PSE&G is providing an application for a license amendment which involves proposed changes to the Technical Specifications to increase the allowable MSIV leak rate from 46.0 total scfh to 200 scfh per main steam line (not to exceed 400 scfh total for all four steam lines) and to delete the MSIV Sealing System. For the MSIV leak rate limit, this application is partly based on the fact that the current limit is too restrictive, and results in excessive MSIV maintenance and l repair, leading to additional MSIV failures, which in turn result in higher leakage rates.

The proposed limit will benefit the public health and safety by reducing the potential for l MSIVs failures, and thus keeping the MSIV leakage within the radiological analysis values.

Page 7 of 8 I.

l l D: cum:nt Contral Dxk LR-N98564 l

At'.schm:nt 5 LCR H98-10 For the MSIV Sealing System, the proposed changes involve a replacement of the existing system with the more reliable and effective main steam piping and condenser method for MSIV leakage treatment. The effectiveness of the proposed method, even for leakage rates greater than the proposed increased allowable limits, ensures that off- l

site dose limits to the public are not exceeded. Overall, the proposed treatment method l can handle MSIV leakage over an expanded operating range, and will thereby resolve the safety concern that the MSIV Sealing System will not function at MSIV leakage rates higher the system capacity. Thus, a margin of safety exists. Furthermore, it is clearly a safety improvement to replace a system with known limitations with the ,

l alternate main steam piping and condenser treatment pathway, which has been shown l l to have excellent reliability. The exemption from 10CFR50, Appendix J, requirements l for MSIV leakage rates is required so that Hope Creek can operate with the proposed l Technical Specifications limit of 200 scfh and with the alternate MSIV leakage treatment l method. This benefit will compensate for any decrease in safety that may result from the granting of this exemption.

Thus, special circumstances exist warranting the granting of the exemption.

F. Environmentalimpact l

The proposed exemption has been analyzed and determined not to cause additional construction or operational activities that may significantly affect the environment. It does not result in a significant increase in any adverse environmental impact previously evaluated in the Hope Creek Safety Evaluation Report (NUREG-1048), result in a

! significant change in effluents or power levels, or affect any matter not previously l reviewed by the Nuclear Regulatory Commission which may have a significant adverse I

environmental impact.

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! The proposed exemption does not alter the land use for the plant, any water uses or impacts on water quality, air or ambient air quality. The proposed action does not affect l the ecology of the site and vicinity and does not affect the noise emitted by station.

l Therefore, the proposed exemption does not affect the analysis of environmental impacts described in the environmental report.

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