ML20247L754
| ML20247L754 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 07/25/1989 |
| From: | Capstick R VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BVY-89-70, GL-88-01, GL-88-1, NUDOCS 8908010343 | |
| Download: ML20247L754 (12) | |
Text
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E T.,4ERMON. TcYANKEE NUCLEAR P'OWER CORPOR.ATION -
~
Ferry Road, Brattletioro, VT 05301-7002 -
- 3 ENGINEERING OFFICE N
I 580 MAIN STREET -
July 25, 1989-BouoN, MA 01740 '
BVY 89-70 (508)779-6711
.. United. States Nuclear Regulatory Commission Document Control Desk
. Washington, DC : 20555
.'l
.' Attention:
.- (a) Docket 50-271 (License No. DPR-28)
(b) USNRC Generic' Letter 88-01, "NRC Position on IGSCC in BWR
.Austenitic. Stainless' Steel Piping," dated January 25, 1988 (c) Letter, VYNPC to USNRC, FVY 88-62, Vermont Yankee's Response to NRC Generic Letter 88-01, dated July 27, 1988
-(d) Letter, USNRC to VYNPC, NVY 89-93, " Inspection 50-271/89-03," dated April-14, 1989
- (e ). Letter, USNRC to VYNPC, NVY 89-114 Request for Additional Information, dated May 24, 1989
Subject:
Vermont Yankee's Response to NRC's Request for Additional Information: USNRC Generic Letter 88-01
Dear Sir:
'By letter, dated July 27, 1988 [ Reference (c)], Vermont Yankee submitted the requested. response in accordance:with the requirements of NRC Generic Letter No. 88-01, "NRC' Position on IGSCC IN Austinetic Stainless Steel Piping
. [ Reference. (b)]. Subsequently, by letter dated May.24, 1989 [ Reference (e)], the
' NRC staff requested that licensees furnish additional information to assist the NRC contractor in reviewing licensee responses to USNRC Generic Letter 88-01.
Vermont Yankee discussed the subject request for additional information with the NRC Project Manager for VYNPS on June 23, 1989 and stated that Vermont Yankee considered its July 27, 1988 [ Reference (c)] submittal to be fully responsive to the-Generic Letter information request. The Generic Letter identified five specific items that would constitute an acceptable response. The response letter
' submitted by Vermont Yankee, [ Reference (c)], fully addressed each of those items.
As stated in Section 8.0 of the staff's April 14, 1989 Inspection Report
[ Reference (d)], Vermont Yankee responded to the subject Generic Letter within the alloted time ~ and addressed all the areas required.
Subsequent discussions with the NRC Project Manager clarified that the request for additional information concerned only sus::eptible welds. Accordingly, Vermont 3 Yankee provides the following additional information:
1.
Position on NRC Staff Positions As stated in Reference (c), with the exception of six items, all Vermont 4
Yankee welds within the scope of Generic Letter 88-01 are Category A.
i The six items that are not Category A are Category D.
These items are
'8908010343'890725
- PDR ADOCK 05000271 B
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' United States Nuclear Regulatory Commission July 25, 1989 Attention:. Document Control Desk Page 2'
]
1 the two core spray safe ends, which have a nonwelded Inconel 600 crevice;
]
the two core spray safe end-to-reactor, vessel nozzle welds, which are_
l
- Inconel 600; and the two core spray safe end-to-reducer welds, which are weld overlaid. We have completed Table 1 from Reference (e) and are providing a copy as Enclosure 1 to this letter.
2.
In-Service' Inspection Program Table 2 of' Reference (e) requested a weld-by-weld listing of inspection history and mitigation action. The attached report " Evaluation of Vermont Yankee Nuclear Power Station for Compliance with USNRC Position on IGSCC in BWR Austenitic Stainless Steel Piping (Generic Letter 88-01)," which was included in Reference (c) and is provided as to this letter, supplies the necessary information in report form. Accordingly, a tabulation in the form of the requested Table 2,
{
has not been separately prepared.
Table 3 of Reference (e) has been completed for the six Category D items,_
and is provided as Enclosure 3 to this letter.
3.
Welds Covered by Licensee Submittal As stated in Reference (c), welde in the Core Spray System outboard of tha first isolation valve were excluded from the scope of the submittal.
The basis for this exclusion is the fact that the Core Spray System is a normally nonflowing line. As such, the temperatures beyond the valve will be less than 200*F.
4.
Welds That Are Not Ultrasonic Inspectable No welds are excluded from the scope of Generic Letter 88-01 because of accessability issues.
5.
Leakage Detection A completed copy of Table 4 is provided as Enclosure 4 to this letter.
We trust this information is responsive to the subject request and will allow the staff to complete its review.
Should you have any questions or require futher information concerning this matter, please contact this office.
Very Truly Yours.
VERMONT YANKEE NUCLEAR POWER CORPORATION h
f!)
Robert W. Ca% tick Licensing Engineer RWC/b11/0447w Enclosures cc: USNRC Region I USNRC NRC Project Manager - VYNPS USNRC Resident Inspector-VYNPS r
__A
- i" 1
e 1
- a ENCLOSURE 1 g 1. " ~
TABLE 1 1
Enagonse's'to NRC' Staff Positiona Licensee' Response
- Licensee Has/Will**
Accept
. Requests 1
with Alternate ' Applied Consider for i
S taf.f._EDsition Ag.cagt FIovisionE' EDAitiDn._ in Past.
Future Use.
1.-
Materials.
'. X
-Yes Yes
'2.:-
Processes X
Yes Yes
,3.- Water Chemistry
- X Yes-Yes
- 4.
Weld-Overlay -
X Yes Yes-5.: Partial Replacement.
'X:
Yes Yes
'6. ' Stress' Improvement of X.-
No No Cracked Weldments 7.~' Clamping Devices X
No Yes
- 8.u Crack Evaluation and X.
Yes Yes
- Repair Criteria 9.
Inspection MSthod X-Yes Yes
' and Personne1' 10.
Inspection Schedules X
Yes tes 11...
Sample. Expansion X
Yes Yes 12..-Leak. Detection X
Yes Yes
- 13. -Reporting Requirements X
Yes Yes Answer with "yes", " check mark", or "X" in appropriate column for each of the 13 NRC staff positions. List and explain each provision and/or alternate position (or reference original submittal if it contains the listing and explanation). Use separate page(s) if needed.
Answer with "yes" or "no", as appropriate, in each column for each of the 13.NRC staff positions.
i
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F.
1 i.V ',.
1 EVALUATION OF VERMONT YAM (EE NUCLEAR. POWER STATION FOR C0ri'LIANCE WITH LBRC POSITION ON IGSCC IN BUR AUSTENITIC STAIN _ESS STwi PIPING (GENERIC Lt.i it:.N 88-01) k
s SLM%RY i
This report documents the status of the Vermont Yankee Nuclear Power Station with respect to compliance with the suidelines contained in USNRC Report, " Technical Report on Material Gefection and Processins Guidelines for BUR Coolant Pressure Boundary Piping - Final Report," commonly called "NUREG-0313, Revision 2."
This report was prepared in compliance with USNRC directives contained in
. Generic Letter 86-01, "NRC Position on IGSCC in BUR Austenitic Stainless Steel-Pipins," dated January 25, 1988.
The seneric letter applies to all' BUR piping made of austenitic stainless steel that is four. inches or larger in nominal diameter and contains reactor coolant at a temperature above 200*F durins power operation, resardless of code classification.
It also applies to reactor vessel attachments and appurtenances such as jet puap instrument penetration assemblies and head spray and vent com-ponents.
With the exception of six items, all of the subject pipins and components at Vermont Yankee meet or exceed USNRC requirements for IGSCC mitigation and cualify for Category A status.
In seneral, all welds have " double mitigation" consisting of a resistant material coupled with a stress mitisating measure.
The six items that do not meet Category A status are the two core spray safe ends, which have a non-welded Inconel 600 crevice, the two core spray safe end-to nozzle welds, which are weld overlaid and the two core spray safe end-to pipe reducer welds which are Inconel.600 base meta,1 welds.
In the following sections of the report, each reactor vessel nozzle and attached system is evaluated for compliance with NUREG-0313, Revision 2.
REACTOR PRESSURE VESSEL The reactor pressure vessel is shown in Figure 1.
There are 15 catesor ies of nozzles on the vessel for a total of 36 nozz les.
The nozzles are identified as N1 through N15. Each nozzle is described below and discussed in detail if it falls under the requirements at Generic Letter l
86-01.
l o
N1A and N1B - These two nozzles are the reactor recirculation system outlet nozzles. They are 28 inch nominal pipe size and are welded to stainless steel safe ends. The safe ends are welded to the recirculation system.
The nozzles are clad with low carbon Type 308 stainless steel weld metal in
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Page 2 l
- the.non-furnace-sensitized' condition. The safe end is. low carbon Type 316 stainless steeli the weld metal is low' carbon Type 308 stainless steel.
The' safe end to nozzle weld was stress mitisated using Induction Heatins
.Stressilmprovement-(IHSI). These are Category A weldments.
.o:
LNZAt through N2K:- These 10 nozzles are the reactor recirculation system inlet nu.zles. J The nozzles aro clad with non-furnace-sensitized low carbon
. Type ~308 stainless steel weld metal'.
The safe. ends are low carbon Type 316 stainless steeli the weldLmetal is low carbon Type 308 stainless steel.
The' nozzle to safe'end weld was IHSI treated. These are Category A weld-ments.
o N3A"throueh N3D - These four nozzles are the main steam outlet nozzles.
i They are manuf actured f rom low-alloy steel and do not 'f all under the s
' requirements of Generic Letter 88-01.
o:
N4A throuah N4D~- These four nozzles are the main feedwater inlet nozzles.
N They are manufactured from low alloy steel and do-not fall under the requirements of. Generic ~ Letter 88-01.
o NSA and N58 - These two nozzles are the core sprav. nozzles. The nozzle to safe end welds are weld overlaid.
The core spray safe ends are manufac-
~
tured from non-furnace-sensitized Inconel Alloy 600.
They contain a non-welded mechanical crevice-from the thermal sleeve (see Figure 2).. The weld between the safe end and pipinsisystem is Inconei 82.
The two welds and
-the~ereviced reelon on each safe end are Categorv D weldments, o
N6A and N6B - These two nozzles on the reactor pressure vessel top head are clad with non-furnace-sensitized low carbon Type 308 stainless steel. The safe ends are l'w carbon Type 304 stainless steel. The safe ends are low o.
carbon Type 304 stainless steel.
The weld metal is low carbon Tyoe 308 stainless steel. These are Category A weldments.
m
.o N2 - This is the-reactor vessel top head vec.t nozzle. The nozzle is clad
.with non-furnace-sensitized low carbon Type 308 stainless steel. The safe end Is low carbon Type 304 stainless steel.
The weld metal is low caroon j
LType 308 stainless steel. This is a Cateecrv A'weldment.
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1434 and NSB - These two nozz les are the jet pumo instrument nozzles. The nozzles are clad with non-furnace-sensitized low carbon Type 308 stelnless steel. The instrument seal assemblies are low carbon Type 304 stainless l
steel. The weld mt
.I is low carbon Type 308 stainless steel. These are Category A weldments.
c' NT
.This is the. control rod hydraulic return line nozzle. The nozzle is clad with non-furnace-sensitized low carbon Type 308 weld metal. The hydraulic return line has been rerouted and the nozzle is capped with a Type 316 stainless steel pipe can elad with low carbon Type 308 stainless J
steel weld metal. This is a Catenerv A weldment.
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Page 3 o
b10 - This nozzle is the core delta P nozzle tap and standby liquid control system injection point.
It is a two-inch nozzle and does not fall under the requirements of Generic Letter 88-01.
o N11A and N11B - These two nozzles are the reactor vessel level instrumen-tation taps. They are two-inch nozzles and do not fal~l under the require-ments of Generic Letter 88-01.
o N12A and N128 - These are,the same as N11A and N118.
c' N13 and N14 - These two nozzles are one-inch leakage taps for the reactor pressure vessel head 0 ring seals. They do not fall under the requirements l
of Generle Letter 88-01.
o
'N15 - This nozzle is-the two-inch' reactor vessel bottom head drain.
It does not fall under the requirements of Generic Letter 88-01.
Thus, with the except' ion of the two core spray safe ends and associated welds, the reactor pressure vessel meets the requirements of Generic Letter i
88-01 for Category A weldments.
PIPING SYSTEMS The Reactor Recirculation System and the Core Spray System are the only two piping systems connected to the reac'.or vessel that fall under the requirements of Generic Letter 06-01.
The Residual Heat Removal System and the Reactor Water Clean-Lip System are connected to the Recirculation Systemi portions of these systems also fall under the requirements of Generic Letter 68-01.
o Reactor Recirculation System - All piping in the Recirculation System is low carbon Type 316 stainless steel. All shop welds were solution annealed and all field welds were IHSI treated (with the exception ci the four-inch bypass line piping, where the welds were performed using water-backed welding). All shop welds were made using low carbon Type 316 stainless steel weld wire, and the field welds were made using low carbon Type 308 stainless steel weld wire.
Cast pump and valve bodies were evaluated for carbon and ferrite content and clad, if necessary, to ensure an IGSCC e?sistant weld region.
The entire Reactor Recirculation System is Cetetory A.
o.
Residual Heat Removal System l
i Same as the Reactor Recirculation System. All stainless steel portions of the Residual Heat Removal System are Category A.
= __- - ____-____._.
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Core Spray System The Core Spray System is normally a non-flowins system.
The portion from the reactor pressure vessel to the first isolation valve
.is low carbon Type 316 stainless steel. The welds are low carbon Type 308 stainless steel. This portion of the Core Spray System is Catewery A.
Since.the system is non-flowins, the temperature will be below 200*F before the first valvel thus, the renaining portion of the system does not fall under the requirements of Generic' Letter 88-01.
o-Reactor Water Clean-Up System - The Reacter Water Clean-Up System pipins is low carbon. Type 304 or low carbon Type 316 stainless steel. The welds are low carbon Type 308 stainless steel. Most welds were performed usins
. water-backed weldins.
The Reactor Water Clean-Uo System is Catenary A.
Thus, all pipins systems felling under the requirements of Generic Letter 88-01 are Catesary A.
SLf1 MARY.
All pipine systems at Vermont Yankee that fall under the scope of Generic Letter 88-01 are Catesary A and do not recuire susmented inspection.
All reactor vessel pressure components and appurtenances that fall under the scope of Generic Letter 88-01 are Category As and oc not require augmented inspections, except for the two core spray safe ends and associated welds. These components are Category D and will require augmented inspection.
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K I&BLE 3 Inspection Schedules j
1
,_Ingpected/To be Inspected / Flaws Found
.J IGSCC '
Weld Diameter Past Fut.ure
,jCategorv.,Svstem No.
Inches Canfiguradon LOM R.O.#X-l_~ Flaw R.O.#X R.0.#X+1-
-t f
- D?
Core 35ASE
' 10.-
Weld.0verlay To be inspected every two refueling
'?
1 Spray A' outages; next inspection is 1990.
j Previous inspections in 1987 and 1989.
D ::
Core
-N5BSE 10 Weld Overlay Spray B D1
- Core F6 8
' Alloy 600/316L Spray A D-Core.
.F6 8
Alloy E 0/316L
~
Spray B D'
Core N/A 10 Alloy 600 Spray A Crevice D
. Core N/A
'10 Alloy 600 Spray B Crevice I.InstructiDna:!
' 1...
Under.the heading, " Inspected /To be Inspected," use as many columns as vrequired to' describe the following:
1
'.a.'
All: previous inspections that were conducted (per NUREG-03'13, Revie'on 2, Page 5.2) using methods and personnel qualified under NRC/EkYl/BWROG coordination plan as upgraded in September 1985.
Elus-b.:
A-sufficient nunber of future inspections to demonstrate that the schedules will follow the NRC staff positions'as given in Table 1 in
. Generic Letter'88-01.
' 2. ;
Replace R.O.# (X-2, X-1, X, and X+1) with actual refue1 Ng outage numbers.. Indicate dates inspections were/will be performed.
s
~ ^ 3.f -List leach' weld'within the scope of Generic Letter 88-01.
_ _ _ _.. _.. _ _ _ _ _ _ _ _ _. _ _ ____________ _ w
1,
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EELOSURE_3 (Continued)
TAEE 3 Inspection.E < ululas 4.
Place an "X" or other appropriate symbol under the appropriate column for each refueling outage for which that weld was inspected or will be inspected.
5.
Indicat'e with "yes" under column marked " flaw" if a flaw indication was found. Attach a statement for each flawed weld giving the orientation j
(axial or circumferential), the dimensions (maximum length and depth'),
and describing any repairs made.
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EECLOSURE 4 y '," ~
.- TAB LE ' 4 '.
b 3i; t
L.
Licensee Positions on Leakage Detection v,
fi '
m
..Already
.TS will be Alternate Contained-
. Changed Position Pssition in TS to Include Propos.ed_"
No.
, No:
Yes 1.'
Conforms with' Position C of Regulatory Guide 1.45.
,y 2.
Plant: shutdown should be initiated when:
'(a) 'within any period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />' No No Yes
~
-or less an' increase is
- indicated in the rate of unidentified leakage in excess 1
of'2 gpm,-.or (b): the total unidentified leakage
-Yes.
N/A attains a rate of 5 spm.
k 3..
Leakage monitored at four-hour No No Yes
. intervals or lesa.
- 4.
Unidentified.. leakage'incluides all Yes N/A
-except:
..(a)I' leakage;into closed systems, or L (b) --leakage _ into the containment atmosphere from sources that are y
located, do not interfere with q
ruonitoring systems; or are not
' from'throughwall crack.
j 5.-
Provisions for shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> No No Yes due to inoperable measurement
' instruments in pirF a with Category D, E, F, or G welds.
.InfirMCAIDan
/
- Place."X".or "yes" under appropriate column for each item.
Provide i
I description andijustification for 4.lternative positions if not already provided.
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