ML20046C310

Forwards Relief Requests RI-24,-25,-26,-27 & -28 from ASME Code Section XI in-service Insp Program

ML20046C310
Person / Time
Site:	LaSalle
Issue date:	08/04/1993
From:	Piet P COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
NUDOCS 9308100122
Download: ML20046C310 (12)

Text

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l e C:mm:nwnith Edison  !

. -i 1400 Opus Place l Downers Grove. Illinois 60515 i

i August 4,1993 ,

Dr. Thomas E. Murley Office of Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 Attn: Document Control Desk

Subject:

LaSalle County Station Units 1 and 2 <

In-Service Inspection Program Submittal of Relief Requests RI-24,-25,-26,-27 and-28 Docket Nos. 50-373 and 50-374

Dear Dr. Murley:

LaSalle County Station performs pressure tests in accordance with ASME Section XI,1980 Edition, Winter 1980 addenda. The enclosed relief requests address section IWD-5223. IWA-5211, IWB-5221, IWA-4400, IWA-5241 i and IWD-5223 for various ;ppbcation of pressure tests. Alternative testing is i proposed for each of the se-tiens as described in the attachments to this letter.

IWD-5223 requires Class 3 systems be subjected to elevated pressure hydrostatic tests. Relief Request RI-24 requests to change this to function or in-service tests.

IWA-5211 and IWB-5221 requires Class 1 systems be subjected to an ,

Operating Pressure Test after disassembly and reassembly of mechanical 1 connections. Relief Requests RI-25 seeks to change this test to 920 psig during start-up for un-isolable Class 1 connections in the drywell. '

IWA-4400 requires that an elevated pressure hydrostatic test be performed after welded repairs or replacements. . Relief Request RI-26 seeks to change this to a nominal operating pressure test for Class 1 and 2 systems. l r

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Dr. Thomas E. Afurley August 4,1993 IWA-5241 requires the VT-2 examination ofinaccessible components to consist of an examination of the surrounding area (floor and surface under the l components) for evidence ofleakage. Relief Request RI-27 proposes an alternate method of monitoring the radiation levels in the tube side of the RHR Heat Exchanger in lieu of an exam under the Heat Exchanger. i IWD-5223 requires a 90% of the pipe submergence head of water pneumatic pressure test on safety and relief valve piping discharging into the - i suppression pool. Relief Request RI-28 requests relief from performing this test -i due to the hardships in set-up and performance. The results of the tests are not l meaningful since the design pressure is 600 psi and actual test pressure would be .

3-5 psi.  !

These relief requests would alter only the type of pressure tests reauired by ash 1E Section XI. This submittal provides methods for alternate monitoring to assure the piping systems have maintained their structural ,

integrity. These alternative testing methods do not introduce any new failure modes.

• Relief Requests RI-24, RI-25, RI-26, RI-27' and RI-28 are applicable to ' i both Units 1 and 2. Commonwealth Edison requests approval of this relief .i request to support the planning and preparation phases of the proposed  ;

alternative tests. It is requested that the proposed relief requests be approved by i October 4,1993. In addition, it is requested that the relief extend through the  !

remainder of the first 10 year Inspection Interval, which will be completed after  ;

each Unit's sixth refueling outage.

Please contact this office should further information be required.  ;

Respectfully, j

/

Y ,

eter L. Piet i Nuclear Licensing Administrator  ;

Attachments: Relief Requests RI-24, RI-25, RI-26, RI-27, and RI-28 for ,

LaSalle County Station ec: J.B. A1artin, Regional Administrator-RIII  ;

J.L. Kennedy, Project Afanager-NRR  ;

D. Hills, Senior Resident Inspector-LSCS ,

Office of Nuclear Safety-IDNS .

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REUEF REQUEST NUIVEER RI-24 (Page 1 of 2)

GQNERNENT_ IDENTIFICATION Code Class: 3

Reference:

Table IWD-2500-1, and IWD-5223(a)

Examination Category: D-A, D-B, and DC ltem numbers: D1.10, D2.10, and D3.10

Description:

Altemate Testing of Class 3 Systerns in Lieu of Ten-Year Hydrostatic Pressure Testing Component Numbers: Various CDDE REQUIREMENT ASME Section XI, Table IWD-2500-1 requires Class 3 pressure retaining components be exposed to VT-2 examinations while the systems are subjected to elevated pressure hydrostatic tests, at or near the end of each inspection interval.

ASME Section XI, IWD-5223(a) states that the system hydrostatic pressure shall be at least 1.10 times the system pressure Psv for systems with a design temperature of 200 F or less. It also states that the system pressure Psv shall be the lowest pressure setting among the number of safety or relief valves provided for over-pressure protection within the boundary to be tested (or, design pressure Pdif over-pressure protection is not provided).

BASIS FOR REUEF Elevated pressure tests are difficult to perform and often represent a true hardship.

Some of the difficulties associated with elevated pressure testing include the following-

- Hydrostatic testing often requires complicated or abnormal valve line-ups in order to properly fill, vent and isolate the components requiring testing.

- Relief valves with set-points lower than the hydrostatic test pressure must be gagged or removed and have blind flanges installed. Bis process requires draining and refilling the system.

- Valves that are not normally used for isolation (e.g., normally open pump discharge valves) are often required to provide pressure- isolation for an elevated pressure hydrostatic test. These valves frequently require tirne consurring seat maintenance in order to allow for pressurization.

. REUEF REQUEST NUNBER RI-24 (Page 2 of 2)

IMSIS FOREEUEE (Continued)

- The radiation exposure required to perform a hydrostatic pressure test is high (in comparison to an operational pressure test) due to the large amount of time required to prepare the system for testing (i.e. installing relief valve gags, installing blind flanges, perforrnir.g appropriate valve line-ups, etc).

He difficulties encountered in performing a hydrostatic pressure test are prohibitive when weighed against the benefits. Industry experience shows that most through wall leakage is detected during system operation as opposed to during elevated pressure tests such as the ten-year hydrostatic tests.

Little benefit is gained from the added challenge to the piping system provided by an elevated pressure hydrostatic test (when compared to an operational pressure test).

The piping stress experienced during a hydrostatic test does not include the significant stresses associated with the thermal growth and dynamic loading associated with design basis events.

These arguments are supported by the adoption of Code Case N498, "Altemate Rules for 10 Year Hydrostatic Pressure Testing for Class 1 and 2 Systems,Section XI, Division 1" This relief request is a natural extension of that Code Case.

Based on the above LaSalle County Station requests relief from the ASME Section XI requirements for performing the ten-year elevated pressure hydrostatic tests on class 3 systems.

PROPOSED ALTERNATE EXAMNATION ,

A VT-2 examination will be performed durir either a system functional test or during a system inservice test, in accordance with me requirements of IWA-5213 (b) and (c) respectively, at or near the end of the inspection interval, prior to reactor startup.

AEELLCAEILE_I]ME PERIOQ ,

Relief is requested for the first ten-year interval of the System Pressure Testing Program at LaSalle County Station Unit 1 and 2.

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REUEF REQUEST NUNEER: RI-25 i (Page 1 of 2)  :

i GQNPONENTIDENTIFICATION 1 Code Class: 1 1

References:

IWA-5211(a)  !

IWB-5221(a)  !

Examination Category: B-P ltem Numbers: B15.10 to B15.71.

Description:

System Leakage Test Pressure for the Disassembly and .l Reassembly of Class 1 Mechanical Connections. 1 Component Numbers: Various

. GODE REQUIRENENTS  :

r IWA-5211(a) requires a system leakage test to be conducted following the opening  !

and re-closing of a component in the system after pressurization to nominal operating j pressure.  !

i IWB-5221(a) states that the system leakage test shall be conducted at a test pressure i not less than the nominal operating pressure associated with 100% rated reactor  !

power. j i

BASIS FORREllEE .!

The norrinal opuating pressure associated with 100% rated reactor power is 1,020 psig. Near the end of each refueling outage, a system pressure test of all Clar.s 1

. pressure retaining components is conducted at 1,020 psig.

Subsequent to the system pressure test conducted during a refueling outage, or during  !

forced maintenance outages which can occur during an operating cycle, it may

• become necessary to disassernble and reassemble Class 1 mechanical connections that are located in the drymil and cannot be isolated from the reactor vessel. For- r these situations, the performance of a Class 1. system leakage test at 1,020 psig - l would have a significant impact on the unit's critical path outage time and personnel j exposure.

r The normal Class 1 system pressure test, which is performed with the vessel flooded i up, requires numerous equipment outages (e.g.,- 380 valves must be taken out-of- j service). Performance of the equipment outages, coupled with the performance of the i system leakage test, takes approximately 5 days (3 shifts per day) with a total l personnel exposure of approximately 2.5 Man-Rent  !

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REUEF REQUEST NUNBER: RI-25 ,

(Page 2 of 2)

BASLS FOR REUEF (Continued)

Pdormance of a system leakage test during normal startup is possible, however, the test can not be perfonned at 1,020 psig. During unit startup, the Electro-Hydraulic Control System precludes a reactor pressure above 950 psig without significant increases in reactor power. In order to achieve a pressure of 1,020 psig, the reador would have to be at approximately 100% rated power. The radiation levels in the drywell at this power level are prohibitive, and prevent drywell entry by plant personnel.

A drywell entry to inspect for leakage can be performed 2 920 psig, which is associated with approximately 15% reactor power. Performance of the leakage test in this manner would have an insignificant impact on the ability to detect leakage from a reassembled mechanical connection. It would also significantly reduce the personnel exposure and critical path outage time required for the test.

Based on the above, LaSalle County Station requests relief from the ASME Section XI requirements for the system leakage test pressure when performing pressure testing of reassembled, unisolable Class 1 mechanical connections.

PROPOSED ALTERNATE PROVISLORS As an altemate examination, LaSalle County Station will perform a system leakage test 2 920 psig during unit startup when an unisolable Class 1 mechanical connection in the drywell has been disassembled and reassembled either 1) subsequent to  !

performance of the system pressure test conducted near the end of each refueling l outage; or 2) during a forced maintenance outage in the course of an operating cycle.

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APPUCABLE 11ME PERIOD Relief is requested for the first ten-year interval of the System Pressure Testing )

Program for LaSalle Units 1 and 2.  !

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a REUEF REQUEST NUNEER: RI-26 l (Page 1 of 3)  !

_C_QLVPONENT IDENTIFICATION l i

Code Classes- 1 and 2 i

References:

IWA-4400(a) i IWA-4400(b) l IWA-5214 1 Examination Categories: B-P, C-H  !

Item Numbers: B15.10 through B15.71  !

C7.10 through C7.41 >

Description:

Attemate Testing for ISI Class 1 and Class 2 j Repaired / Replaced Components.  :

Component Numbers: All Class 1 and Class 2 pressure retaining components  ;

subject to Hydrostatic Testing per IWA-4700.  !

CODE REQUJBENENE IWA-4400(a) requires an elevated pressure hydrostatic test to be perforrned after l welded repair / replacement of classed components, except those exempted by IWA-  ;

4400(b).  ;

BASIS FOR REUEF Elevated pressure hydrostatic tests are difficult to perform and often represent a true hardship. Some of the difficulties associated with elevated pressure testing include the ,

following:  !

- Hydrostatic testing often requires complicated or abnormal valve line-ups in . l order to properiy vent, fill and isolate the component requiring testing. l t

- Relief valves with set-points lower than the hydrostatic test pressure must be k gagged or removed and blind flanged. This process requires the draining and 1 refilling of the system.  !

r

- Valves that are not normally used for isolation (e.g., normally open pump -

discharge valves) are often required to provide pressure isolation for an  ;

elevated pressure hydrostatic test. These valves frequently require time  ;

consuming mat maintenance in order to allow for pressurization. j

- The radiation exposure required to perform a hydrostatic pressure test is high 3 (in comparison to operational pressure testing) due to the large amount of time  :

required to prepare the volume for testing (i.e. installing relief valve gags,. :j performing appropriate valve line-ups, etc). i k:\pete\ relief \5  !

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REUEF REQUEST NUMBER RI-2fi (Page 2 of 3)

The difficulties encountered in performing a hydrostatic pressure test are prohibitive when weighed against the benefits. Industry experience, which is corroborated by LaSalle County Station's experience, shows that most through wall leakage is detected during system operation as opposed to during elevated pressure tests such as ten-year system hydrostatic tests.

Uttle benefit is gained from the added challenge to the piping system provided by an elevated pressure hydrostatic test (when compared to an operational test). The piping stress experienced during a hydrostatic test does not include the significant stresses affiliated with the thermal growth and dynamic loading associated with design basis events.

These arguments are also supported by the adoption of Code Case N-498, "Altemative Rules for 10 Year Hydrostatic Pressure Testing for Class 1 and 2 Systems,Section XI, Division 1" This relief request is a logical extension of that Code Case.

In addition to pressure tests, non-destructive examinations performed on repair / replacement welds and metal removal sites provide assurance of component integrity.

Based on the above, LaSalle County Station requests relief from the ASME Section XI requirements for performing elevated pressure hydrostatic tests on Class 1 and 2 repaired / replaced components.

PROPOSED AlJERNATE PROVISLONS NDE shall be performed in accordance with methods and acceptance criteria of the applicable Subsection of the 1992 Edition of Section Ill.

A VT-2 visual examination will be performed with the Class 1 or 2 repaired / replaced component pressurized to nominal operating pressure. This visual examination will be performed after nominal operating pressure has been held for the following times:

- Non-Insulated components shall be held at nominal operating pressure for 10 minutes prior to examination.

- Insulated components shall be held at nominal operating pressure for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />  ;

prior to examination.

REUEF REQUEST NUNEER: RI-26 (Page 3 of 3)

APPUCABUGMELEEBMXL Relief is requested for the first ten-year interval of the System Pressure Testing Program for LaSalle Units 1 and 2.

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. I REUEF REQUEST NUNEER: RI-27 ,

(Page'1 of 1) l i

COlVPONENT IDENTIFICATION Code Class: 2 ,

Reference:

IWA-5241(b)  !

Exanination Category: C-H i Item Numbers: C7.10, C7.11  !

Description:

Attemate Testing for Residual Heat Removal Heat  !

Exchanger Tubes.  !

Component Numbers: Unit 1: 1E12-B001A,1E12-B001B -l Unit 2: 2E12-B001A, 2E12-B001B 1 l

t COREEEQUlBENEliI IWA-5241(b) states that the VT-2 visual examination of inaccessible components shall ,

consist of an examination of the surrounding area, including floor areas or equipment  ;

surfaces located underneath the components, for evidence of leakage. 1 B& SIS FOR RFIIEF 'l The tubing inside the Residual Heat Removal (RHR) Heat Exchanger is inaccessible. l A visual examiner cannot enter the RHR Heat Exchanger to perform an examination of ,

' the tubes or their surrounding areas during operational or hydrostatic pressure testing.  !

t Based on the above, LaSalle County Station requests relief from the ASME Section XI requirements for perfoming a VT-2 visual examination of the RHR Heat Exchanger  ;

tubing during hydrostatic and operational pressure tests. 1 i

EBRERSED ALTERNATE EXAMNATION j Monitoring of radiation levels in the tube side cooling water will be performed during '!'

the shell side pressure test as an attemate rnethod of verifying tube integrity. Levels within Technical Specification limits will be considered acceptable. l AEE1LCABuillNE.EEBlQQ -

l Relief is requested for the first ten-year interval of the System Pressure Testing ' i 1

Program for LaSalle Units 1 and 2.

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REUEF REQUEST NUNEIER Rl-28 I (Page 1 of 2) ,

CONPONENT IDENTIFICATION l Code Class: 3  !

Reference:

IVD5223(f) l Examination Category: D-B l Item numbers: D2.10 i

Description:

Exemption From Pressure Testing Piping Beyond the Last  !

Safety Or Relief Valve Which Discharges into Re j Suppression Pool i Component Numbers: Various CODELBEQUlBENENI ASME Section XI 1980 Edition, Wnter 1980 Addenda, IWD-5223(f) states "For safety or relief valve piping which discharges into the containment pressure suppression pool, a pneumatic test (at a pressure of 90% of the pipe subnergence head of water) that  ;

demonstrates leakage integrity shall be performed in lieu of system hydrostatic test."

BASIS FOR REUEF l LaSalle County Station has eighteen Main Steam Relief Valves with associated -  !

discharge lines and vacuum breakers. The discharge lines run down through the -

drywell and discharge into the Suppression Pool.

Normal plant operation calls for these lines to be pressurized only during periodic lift tests which verify the set point of each Main Steam Relief Valve. All discharge piping  ;

is contained inside the drywell. At the power level during these lift tests, the radiation  :

levels in the drywell are prohibitive and prevent inspection personnel from entering the ,

drywell and performing VT-2 examinations during the Relief Valve functional testing.

The provisions of IVD5223(f) call for a pneumatic test at a test pressure of 90%

submergence head to be performed The design of the Main Steam Relief Valves and _;

associated discharge lines at LaSalle County Station does not allow for such a test to e be performed that would demonstrate leakage integrity. Per 10CFR50.55a section i (g)(4), Code Class components shall meet the requirements of ASME Section XI to extent practical within the limitations of design, geometry, and materials of construction of the components.

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REUEF REQUEST NUlVEER: RI-28 ,

(Page 2 of 2) -

SASIS FOR REUEF (Continued) l No test taps are currently available on these discharge lines to allow proper pressurization and depressurization of the system. The pressure associated with 90% i submergence head in these lines relates to approxirnately 3-5 psig, while the design 1 pressure of the discharge lines is 600 psi. The normal surveillance lift test is - t performed at a minimum vessel pressure of 600 psig and is thus the more challenging i test. Also at the low test pressure of the submergence head test, the vacuum '

breakers are not designed to provide a leak tight seal and would provide another leak path that would prevent verification of component integrity. .

Based on the above, LaSalle County Station requests relief from the 1980 Edition, t Wnter 1980 Addenda ASME Section XI requirements for conducting a VT-2  ;

examination under normal operating conditions and from the hydrostatic test requirements to perform a pneumatic test at 90% pipe submergence head once every  !

inspection interval.

• PROPOSED ALTERNATE EXAMNAT10N No altemate examinations are proposed.

i APPUCABLE T11VE PEBLQQ Relief is requested for the first ten-year interval of the System Pressure Testing

• Program at LaSalle County Station Unit 1 and 2.

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