ML20214P845

Forwards Explanations & Justifications in Response to Items 86-18-05 & 86-18-06 of Insp Rept 50-312/86-18 Re RCS High Point Vent Piping Classification.Classification Not Modified to Install Sys Required by NUREG-0737,II.B.1

ML20214P845
Person / Time
Site:	Rancho Seco
Issue date:	09/16/1986
From:	Julie Ward SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.1, TASK-TM JEW-86-285, NUDOCS 8609240074
Download: ML20214P845 (10)

Text

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SACRAMENTO MUNICIPAL UllLITY DISTRICT O P. O. Box 15830, Sacrainento CA 95852-1830,(916) 452-3211 AN ELECTRIC SYST Bl T g OF CALIFORNIA JEW 86-285

,,p-September 16, 1986 JOHN B MARTIN ADMINISTRATOR U S NUCLEAR REGULATORY COMMISSION REGION V 0FFICE OF INSPECTION AND ENFORCEMENT 1450 MARIA LANE SUITE 210 WALNUT CREEK CA 94596

SUBJECT:

NRC INSPECTI0ll REPORT NO. 86-18 ITEMS 86-18-05 AND 86-18-06, RCS HIGH POINT VENT PIPING CLASSIFICATION

Dear Mr. Martin,

In response to Paragraph 5, High Point Vent Piping Classification, of Inspection Report No. 50-312/86-18 dated June 20, 1986, the attached explanations and justifications are submitted regarding the classification of the Reactor Coolant System high point vent oiping for Items 86-18-05

( Attachment 1) and 86-18-06 ( Attachment 2).

Should you have any questions, please contact Mr. Dave Abbott at (916) 452-3211, extension 4940, or Mr. Jerry Delezenski at (916) 452-3211, extension 4909, of my staff.

. Ward Deputy General Manager, Nuclear Attachments (2) 8609240074 860916 2 PDR ADOCK 0500 ,

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l DISTRICT HEADQUARTERS O 6201 S Street, Sacramento CA 95817-1899

ATTACHMENT 1 ITEM 86-18-05 CLASSIFICATION OF THE RCS HIGH POINT VENT PIPING The design of Rancho Seco is based on the requirements of the 1968 issue of 10 CFR that was in effect at the time of issue of Construction Permit CPPR-56 on October 11, 1968. It was designed and constructed to meet the intent of the General Design Criteria (GDC) as originally proposed in July 1967. The plant was subsequently assessej against the revised 1971 GDCs (Appendix A to 10 CFR 50) and was found to conform to the intent of the revised GDCs as indicated in the SER.

Neither the 1968-10 CFR 50 nor the GDCs (1967 and 1971 versions) define reactor coolant pressure boundary. Not until 1971 was the definition of reactor coolant pressure boundary codified in 10 CFR 50 in sub-sections 50.2 (v) and 50.55a. Even the .USAS code B31.7 June 1968, that was used for the reactor coolant system does not define the boundary of Class 1.

Up to 1971, the boundary of the reactor coolant system was defined by the NSSS Suppliers and the AE's interpretation of 10 CFR and applicable industry codes and standards. For Rancho Seco, the reactor coolant pressure boundary (or Class 1 boundary) was defined as follows:

Class 1 (USAS B31.7) will be applied to the reactor coolant system pumps and piping, and the pumps, valves, and piping connected to the reactor coolant system out to and including the first isolation valve if the valve is normally closed, otherwise out to and including the second isolation valve.

This arrangement was the original design agreed upon by the NSSS Supplier (B&W), the AE (Bechtel), and SMUD. The resultant desig'ation n for the piping systems is llN1 - Quality Class 1, Seismic Category 1, Nuclear Class 1 (USAF j B31.7) for the reactor coolant pressure boundary. (For current definition of SMUD project classification see Attachment 3).

However, standard industry practice was to provide two isolation valves from high pressure /high temperature fluids for personnel protection. Therefore, a second closed isolation valve was included in the design, but was designated as 22N2 for the reason that it is outside the reactor coolant pressure boundary per the definition above. The seismic design extends into this piping usually including the second valve. Functionally, this piping and valve provide the second barrier from the reactor coolant.

The design of the original high point vent piping follows the philosophy of the original design criteria described above under which the plant was licensed. In this case, the seismic analysis extends into the nitrogen supply system piping past valve RCS-Oll (See Figure 1). The nitrogen supply piping (for process reasons) is classified as 33 (Quality Class 3, Seismic Category 3), but is structurally designed and analyzed to meet Seismic Category I requirements up to a structural anchor.

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Although the Safety Guides were issued several years later, this design meets the requirements in Safety Guide 29 (now Reg. Guide 1.29) which states;

" Category I seismic design requirements should extend to the first seismic restraint beyond the defined boundaries. Structures, systems, or components which form interfaces between Category I and non-Category I features should be designed to Category I requirements." (Emphasis added.)

! Classification of the RC vent piping (22N2) and the nitrogen supply piping i

(33) is in accordance with the Safety Guide and the original licensing basis of the plant. This classification was not modified to install the High Point Vent system required by NUREG 0737 II.B.l. The vent line from the first isolation valve to the piping supports in the nitrogen supply line has been analyzed to Seismic Category I requirements.

Therefore, the District feels that the classification of the original high point vent piping met or exceeded the guidance available at the time, and that the design functionally provides the double barrier protection fM uie RCS as required by current-day standards. Application of more Swetit requirements than those in effect six months before t the operating license application for Ranche Se c hu,M date bmitted on ot docketing of April 27, 1971) must be reviewed hs Mght of 10 CFR 50.109 Backfitting requirements, furthermore, all new piping systems, including that which was added for the RC High Point Vent, have two QA Class 1 isolation valves that conform to the requirements as defined in the current 10 CFR 50.2(v) and 50.55a.

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. ATTACHMENT 2 ITEM 86-18-06 IDENTIFY AND CONTROL THE PIPING AND SUPPORTS OF NON-SEISMIC CLASS I SYSTEMS THAT ARE USED IN THE SEISMIC ANALYSES Existing design control procedures are in place which control all changes to plant configuration including non-class I systems. However, the District recognizes the need to administrative 1y control the piping and supports beyond the designated boundary that were included in the seismic analysis.

Therefore, the District is developing a program that will identify the piping and supports of non-Class 1 systems that are used in the seismic analyses and that provide structual support functions without imposing the Quality Assurance Class 1 requirements on piping that was originally designated as Quality Assurance Class 2 and 3. Outlined below is the program that is beins incorporated into the Nuclear Engineering Procedures.

The following paragraphs are being added to the Nuclear Engineering Procedures for identifying seismic Class 2 and 3 piping and supports which are included in the seismic analyses.

Piping systems are generally analyzed between anchors, with the termination anchor located almost invariably beyond the process classification break defined on the P&ID. If the anchor is beyond the defined seismic Category 1 boundary, a set of restraints may be justified to simulate an " effective" anchor for isolating the effect of the non-seismic piping on the seismic piping. Generally, two supports in each of the three orthogonal directions are adequate to provide this separation. However, on a case-by-case basis, a lesser number of supports may be justified to provide an " effective" anchor. The location of the termination anchor or the last restraint of the

" effective" anchor marks the design interface between the seismic Category 1 and non-seismic catagory 1 piping. All piping and sup; from anchor to the seismic 1 and non-seismic 1 design interface, l inclusively, shall be designed to withstand both the OBE and DBE j earthquakes.

To preclude unauthorized deviation from design, it shall be the responsibility of the analyst to ensure that the design interface is clearly marked on the issued fabrication isometric and stress isometric drawing. Refer to Figure 3 for method of marking the isometric drawing. Moreover, the analyst shall be responsible for ensuring that all issued drawings of pipe supports line designation list and Master Equipment List for non-seismic Category 1 piping within the seismic Category 1 design boundary shall be marked with a project classification 21 or 31.

Schedule of Imolementation:

The above mentioned procedure change will be implemented October 31, 1986, for all new drawings that will be issued after this date.

All drawings previously issued which'are presently in the District system will be revised by December 31, 1987.

0034E

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Attachment 3 NEPM inden No. l 5101.2 9 $SMUD sacnawnto musmem uvurv oestmer DESIGN CRITERIA t..d o,.c gi,n.

MECHANICAL

Subject:

PROJECT CLASSIFICATION OF EQUIPMENT Quality Class: Seismic Category N/A N/A NRC General Design Criteria:

N/A NRC Regulatory Guides:

N/A NRC Branch Technical Paper or SRP:

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USAR Section: Appendix 1B and SB P & ID: N/A Other:

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I 4- 3 SMUD 1457a 4/85 Page 1 of 4

NEPM imMx No.

5101.2 8 "" $SMUD sacnaassaro envenem unury oestmer DESIGN CRITERIA t..o omc.,i,o.

MECHANICAL PROJECT CLASSIFICATION OF EQUIPMENT 1.0 PURPOSE This section provides direction for project classification of equipment.

Project classifications are a shorthand method of indicating the quality and seismic categories and the code under which design, procurement, manufacture, fabrication, erection and installation are to take place.

2.0 SCOPE The classification system covers all equipment in the plant. From a practical standpoint.it covers any item which has a tag number.

3.0 DEFINITIONS Not Applicable 4.0 GOVERNING CODES AND INDUSTRY STANDARDS

,g Not Applicable S -

5.0 DESIGN CRITERIA The project-classifications for piping, valves and equipment consist of a combination of digits and letters. The first digit represents the quality class; the second digit indicates seismic class and the third indicates the applicable code.

When a nuclear code is involved, an "N" between the second and third digits designates that the component is part of a safety system and all the requirements of the applicable nuclear code class apply. The code class in nuclear components is indicated by the third digit.

l The quality classes are indicated by numbers 1 or 2 as defined in the Rancho Seco Quality Assurance Program Manual Section 3, and FSAR Appendix 1B. A 3 in l the quality class position indicates no quality assurance is required and commercial quality control practice is adequate.

The seismic categories are indicated by numbers 1, 2, or 3 representing the three seismic categories defined in FSAR Appendix SB.

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- 1 NEPM imhx No.

5101.2

$SMUD DESIGN CRITERIA

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sacnamento uvwcm um oesw MECHANICAL l

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1 5.1 CODES l The last digit of all equipment project classifications, regardless of whether nuclear or nonnuclear, represents the applicable code under which design, procurement, manufacture, fabrication, erection and installation are made.

The following is the definition of these numbers:

Equipment Design Classification Last Digit Applicable Code 1, 2 or 3 See Design Criteria 5108.2 for definitions 4 ASME B&PV Code,Section I 5 TEMA, Heat Exchange Institute Standards 6 American Petroleum Institute 7 Hydraulic Institute Standards 8 ASME B&PV Code,Section VIII _,

T 9 Other \s /

9A ASHRAE, AMCA X Manufacturer's Standard (No applicable code) 5.2 EXAMPLES The following are examples of project classification use:

(1) Nuclear Equipnent Classification The following example would be interpreted as follows: ,

Seismic Category I - Nuclear equipment (ASME III, B31.7, or ASME Pump and Valve Code, whichever is applicable)

Quality Class 1-1 1 N 2 I

Nuclear Class B or 2 (whichever is applicable) 1754V 3 Initial Issue

NEPM index No.

5101.2 O $SMUD DESIGN CRITERIA t..a o,.C.,uo.

sACRAWNTO MUNtCM UTERY OtSTmCT MECHANICAL (2) Nonnuclear Equipment Classification The following example would be interpreted as follows:

Seismic Category I - ASME B&PV Code Section VIII Quality Class

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1754V Page 4 of 4

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