ML20203L541

Discusses Potential Shrinkage Flaws in Feedwater Check Valve Bodies.If Valve Body Insps Disclose That Internal Shrinkage Cracks Have Propagated to Either Surface,Valves Should Be Replaced Per NUREG-0991 (Ser).Related Info Encl

ML20203L541
Person / Time
Site:	Limerick, 05000000
Issue date:	03/21/1986
From:	Rehm T NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:	Joseph Austin Office of Nuclear Reactor Regulation
Shared Package
ML20203L508	List: ML20203L505 ML20203L510 ML20203L514 ML20203L518 ML20203L527 ML20203L531 ML20203L539 ML20203L541 ML20203L544
References
FOIA-86-126, FOIA-86-127, FOIA-86-131, FOIA-86-166, FOIA-86-201, FOIA-86-209, FOIA-86-263, FOIA-86-80, FOIA-86-82, RTR-NUREG-0991, RTR-NUREG-991 NUDOCS 8608270381
Download: ML20203L541 (7)

Text

~

y9 ,6 U. ga > w e

. -'*- +

i*

[ o g UNITED STATES F" n NUCLEAR REGULATORY COMMISSION h WASHINGTON, D. C. 20555

+

..... MAR 211986 Docket Nos.: 50-352

. 50-353  ;

i MEMORANDUM FOR: JohnH.Abstin,TechnicalAssistant to Commissioner Asselstine FROM: T. A. Rehm Assistant for Operai.ioas, ED0

SUBJECT:

LIMERICK COMPLIANCE WITH GDC-51 In your memorandum to me dated February 28, 1986, you requested certain information with respect to a particular staff input for the Limerick Safety Evaluation Report and several subsequent letters from the Philadelphia Electric Company (PECo) in 1984. The documents deal with potential shrinkage flaws in feedwater check valve bodies. We believe that this issue was appropriately resolved and that there was no compromise of the staff's safety review procedures. The following discussion which includes some pertinent background information, will serve to place this issue in the proper perspective, and should provide the information you requested.

During the staff's review of the Final Safety Analysis Report for the Limerick Generating Station in 1983 and 1984, the staff determined that two cast bodies for the feedwater check valves contained shrinkage cracks that could compromise the valves' conformance with GDC-51 if the cracks were to propagate while in service. Such propagation of the shrinkage

. cracks has also occurred in the past and has been documented for similar valves at other plants. After a fracture mechanics evaluation was com-pleted and submitted by PECo for the staff's review, an independent fracture mechanics evaluati6. was performed by the NRC staff. It was determined by the staff that a special inservice inspection of these valve ~ bodies (valve IF074 A and B) would be required.

The resolution of this issue is addressed in the NRC staff's input to the SER, dated September 18, 1984, two PEco letters dated October 4 and 12, 1984, and Supplement No. 3 to the Limerick SER (NUREG-0991) issued in October 1984. Specifically, the supplement to the SER stated that:

"We have concluded from these calculations that although the valve body may not quite meet the Appendix G requirements, even our most conservative approach still shows some safety mar Adequate margin against failure (at least a factor of two) gin. will exist under the most probable loading conditions.

Contact:

R. E. Martin x29472 8608270381 860826 y PDR FOIA gT/

GARDE 86-80 PDR -

---

i

These conclusions assume that the flaw size assumed will not be exceeded significantly. However, service experience on similar castings has disclosed that normal, acceptable shrinkage may be extended by cracking

, during service. We, therefore, recommended to the applicant that these valves be inspected for surface cracks on the inside and outside surfaces at the first refueling outage and at other times when the valve is disassembled for maintenance. The applicant has committed, by . letter dated October 12, 1984, to including this augmented inspection by surface examination or other methods acceptable to the staff, which will be determined during the staff's review of the inservice inspection program.

We have concluded that the results of our evaluation and the augmented inservice inspection program for these valves will provide reasonable assurance of compliance with the requirements of GDC-51. It will be confirmed by the augmented ISI that the shrinkage flaws existing in the valve bodies on entering service have not propagated to either of the surfaces. Should the augmented ISI disclose that these flaws have propagated to either of the surfaces, the valves are then to be replaced by the licensee."

With respect to the issue raised by the PECo letter of October 4,1984, i.e., whether a surface crack of up to 3.5 inches in length would be acceptable, the staff's position has been and continues to be that if the valve body inspections disclose that internal shrinkage cracks have propagated to either surface, the valves are to be replaced, regardless of the length of the surface indication.

It should be noted that the alternative approach proposed by PECo in its letter of October 4,1984, was found to be unacceptable by the staff and PECo was so informed; whereupon, the PECo proposed approach described in its letter dated October 12, 1984, was submitted and determined to be acceptable. The staff findings reflected in the September 18, 1984, staff memorandum referred to in your memorandum were included in SSER-3, as discussed above. There has been no change in the staff's position from that stated in SSER-3.

. . 'm .

Assistant for Operations, ED0 cc: P. Polk C. Acer J. Myer M. Clausen OPE OGC SECY

. .** r 1 (3)

Stu~dsvik Datum - Date Var referens - Our reference 4 1985-12-31 RN/CH Handleggere - Metter handled by Ert datum - Your date Er refe-ens - Your reference

. Re: Marviken Intermediate Programmes (MXIP)

- July 1st - December 31st 1985.

LETTER ACREEMENT P BLE Following the outcome of deliberations at the MX-V-ATT

- Project Board meeting on June lith, 1985 (reference to PROTOKOLL PB 2/85 NorrkBping) STUDSVIK ENERGITEKNIK AB (herein called STUDSVIK) issued through the chairman of the MX-V-ATT Project Board an invitation letter of June

'i 28th, 1985, to the MX-V-ATT Parties to participate in and

'f financially support the Marviken Intermediate Programmes

'E MXIP consisting of three items, namely A) Marviken ATT t; Facility Standby, B) Organization and perfonnance of an iI Ad-hoc Working Group - assisted by a Technical Secretariat -

){ for analysis and assessment of the need of further aerosol Q transport tests using the Marviken Facility, and C) Experimenta TE and studies on specific phenomena which would mainly I contribute to the enderstanding of the findings of the ATT 1arge scale experiments (" Package 1").

[J - .

j,

,r ~~~

The above items A) and C) Package 1 were described in the y document MXIP-1001 (Appendix to the June 28th letter).

Pt Further details on Package 1 work items were provided Ff* in the reports MXIP-1, -2, -4, -5, all dated 1985-08-29, and MXIP-3, dated 1985-09-17.

E fh The mandate and performance of item B) Ad-hoc Working

+l Group was described in the document MXIP-1003 (Appendix to

,; the June 28th letter).

.I ht

_.; AGREEMENT BASIS Th'e total cost for A), B) and C) together - including all

-- operations and final reporting - was ESEK 4640. After the first formation of A), B) and C) items a strong wish by the ATT parties that an earlier discussed upgrading of an ATT internal corium shakedown report should be undertaken, introduced a new cost amounting to KSEK 320.

B

/

/

1985-12-31 2 (3)

The technical priorities for work-items within item C)

" Package 1" with respect to the expected usefulness of results in relation to efforts and costs have been

- successively discussed and refined, the technical content now being summarized after observations at the October 16th ATT TAC meeting (reference is made to TAC meeting minutes 2/:85). The final approach is that C) Package 1 as itemized after the technical modifications is still to be performed wi' thin the cost frame of KSEK 2965 (Appendix I).

-- The properly amended corium shakedown report costed to KSEK 320 and described by report MXIP-6, dated 1985-09-13, should be presented along with the final reporting of

i MXIP Psckage 1.

i

,f The MXIP operations are scheduled for finalization at the

.! end of 1985, except that work with final reporting has to be pursued for some time into early 1986.

[{6 Ej The identified costs for the total MXIP proper hence remain to be KSEK 4960 which is postulated to be a firm E.

EE amount, as are the cost elements for A) 1050, B) 625, for

• ~j C) 2965, and D) KSEK 320.

-? j

{ ATT Parties having declared interest and firm intent to

}

par'icipate in and financially support MXIP are: OH, VTT, L:s CEA, EDF, ENEA, JG, KEMA, SKI, UKAEA, EPRI, NRC and STUDSVIK.

C.t

.I MX1 operations were started on July 1st 1985 and on the I bai.s of delared interest and firm intent from ATT Parties j fp a decision to pursue operations was announced to the Parties on August 12th, 1985, by telex message to the t . Parties.

L The general provisions of the MX-V-ATT project sgreement

,3 of 1982-12-08 apply if not otherwise stated in this l

[T present agreement including its preamble and agreement l . I basis or do not apply with respect to the content, duration i

and other circumstances obviously different from the ATT l project profile.

Obligations and rights with respect to results and information remain the same.

l 1

~

sn a

1 3 l 1

M 1985-12-31 3 (3)

AGREEMENT Now, as United States Nuclear Regulatory Commission, USA

.. (herein called NRC) has given a declaration of interest and firm intent to be a Party to MXIP operations and as al,1 other parties listed in the MX-V-ATT Project Agreement of 1982-12-08 are expected to join MXIP the following agreement is entered into between NRC and STUDSVIK ENERGITEKNIK AB, Sweden: l NRC. will have access to the MXIP operations and results in items A), B), C) and D) - upgraded corium shakedown report - on terms and conditions stated in the ATT Project

.$ Agreement of 1982-12-08 if not otherwise stated in this i letter agreement and further notes:

! - The total amount to be invoiced to NRC by

• j STUDSVIK for th'e MXIP project is KSEK 615 t- e, based upon the NRC share 12.4 % of KSEK 4960.

[~

Invoicing shall be made in one step during December, 1985 and payment shall be made in F accordance with ATT rules i.e. within 60 days.

a,

" - STUDSVIK undertakes to conclusively / perform the scheduled items A), C) and D) as close to g.. .g agreed schedule as possible. STUDSVIK will also a Lg try to f acilitate item B) Working Group (including d Technical Secretariat) operations. STUDSVIK cannot be made liable for delays or other

']

' changes in the work and its resalts deriving Ih' from majority ruling of the other Parties h (other than STUDSVIK and NRC).

"e - Should finally such lack of financing from

( other Parties occur that would seriously harm

! I

i. the performance of the programme, STUDSVIK is liable to inform NRC without undue delay.

' STUDSVIK and NRC shall together with the other Parties assess the situation in accordance with ruling of the MX-V-ATT Agreement.

Done on December 1985.

i l

For For United States Nuclear STUDSVIK ENERGITEKNIK AB Regulatory Commissio ,

l

, g.,

c Q f

/

I C 1

i

, . . e 1985-11-27 APPENDIX I:1 (2) e*

MARVIKEN IlfrERMEDIATE PROGRXWES, MKIP ITEM C) PACKAGE 1 At the ATT PB 2/85 meeting the Board decided that the Marviken facility should be kept in stand-by status to

- December 31st, 1985. During the stand-by additional experiments and investigations are carried out to support

! ari~ improved understanding of the acquired ATT results (see MXIP-1001). The investigations utilize equipment and personnel from the ATT Project and comprise the following progran items described in the reports MX1P-I

through 5:

E 6

i -

Carbon release from the corium chamber during

( operation. (Graphite issue, MXIP-1).

Particle size evaluation and analysis (MXIP-2).

Resuspension phenomena'under typical ATT conditions.(MXIP-3).

• e f -

Flow pattern studies in the reactor vessel and g at the pressurizer outlet (MXIP-4).

Formation of stable chemical compounds in

% the facility during the tests carried out.

1 (Chemical effects MXIP-5).

a i The individual items in this Package 1 programme have j been subject to detailed discussions concerning their 5 importance with respect to ATT oriented verifications and

.[

7 their technical feasability within the limitations of b equipment available. In consideration of the very narrow

~

.. tiime schedule the review activities have been performed la parallel to the preparatory work at the MXIP test facility.

, Sununarizing the discussions within the ATT TAC and MXIP Working Group led mid-October to the following underlining of relative importance of the individual items:

m O

1

(, -

• 1985-11-27 APPENDIX I:2 (2) 4

- Particle size studies should be given high

, priority and be supported with best available resources.

- Resuspension test data have a lesser importance for the time being and tests-should be performed simultaneously with particle size testing to

minimize expense.

Flow pattern data are of great importance. The 4

present investigations could provide qualitative

support to the ATT data.

- Chemical effects studies are given high priority and should be performed as planned.

~ t-The cost for the major part of the Package 1 program is l*[

,i essentially composed of two categories namel'y a) costs i

for the MXIP facility and perparatory work with insignificant i

$ sensitivity as to the number of tests planned for individual items, b) particular costs tied to the performance of individual tests.

7 ,

i m.

The discussed and implemented modifications in the program g are essentially leading to a transfer of particular costs y from one item to another. The Package 1 cost (KSEK 2965) li. earlier calculated and offered with respect to resources being made available for the period July 1st - December

,[

31st, 1985, will allow the modified Package 1 program to be

!I concluded in a timely manner. The final reports will to appear early 1986.

j

'?t 4 .

_f .

m

, _ . _ _ , _ . , . _ . , _ _ _ . - . . . , , . . , .__