ML19339A895
| ML19339A895 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 11/17/1976 |
| From: | Vanderburgh D YANKEE ATOMIC ELECTRIC CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| WYR-76-116, NUDOCS 8011050653 | |
| Download: ML19339A895 (5) | |
Text
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I Telephone 6l7 366-9011 Negulatory Dcchet Eile
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YANKEE ATOMIC ELECTRIC COMPANY 171 20 Turnpd:e Road Westborough, Mossachusetts 01581
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November 17, 1976 United States Nuclear Regulatory Commission h.
Washington, D. C.
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Attention: Office of Nuclear Reactor Regulation f "A
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Reference:
(a) License No. DPR-3 (Docket No. 50-29) \\(s o7N (b) Proposed Change 131 submitted September 25,4975.,
(c) NRC letter dated August 25, 1976 (Dockec No. 50'29)'.
Dear Sir:
As requested by Reference (c) the following is an outline ofn ' '#
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in-situ inspection program for the presence of the poison materi
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g (Boral) in the new spent fuel racks. This inspection program w i poemo N'
verify the presence of sufficient Boral to ensure Keff <.95.
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I.
BACKGROUND O'
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, a a The rack design for Yankee Nuclear Power Station consists Dadd ter P P individual square storage cavities each containing Boral on all. 42 g
sides; therefore, between any two adjacent cavities there are two 4 % g a of Boral.
In the original proposed change submittal (Reference (b))
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Keff was stated as 0.796 including calculational uncertainties.
This value vould change to 0.927 if one of the two Eoral sheets is missing between each cavity. Taking this design conservatism into account, only 50 percent of the Boral would have to be accounted for; one sheet between adjacent cavities. This approach totally ignores the fact that an extensive QA program verifying the presence of Boral was implemented by the rack manufacturer.
This quality assurance program has been discussed with you in two letters and one meeting.
II.
TEST PROGFAv.
The physical hardware for the test consists of a neutron source (Pu-Be) surrounded by polyethylene, neutron detectors (fission chambers) and electronic recording equipment. Basically, the source will be inserted in one cavity and a detector in an adjacent cavity. The source and detector will be mounted on s rigid frame which will fix their positions relative to each other. By knowing what the detector readings should be with and without Boral present a "go, no-go" inspection system can be established.
Preliminary testing has been performed using cavity models which are full scale in cross-section. Two model cavities were 8011030 8 9 1,,. w
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United States Nuclear Rrgulatory Commission Nover.ber 17, 1976 Attn: Office of Nuclear Reactor Regulation Page Two I
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deliberate 1'y made with aluminum rather than Boral in one side of each.
With these models, detector readings in counts per minute (CPM) were measured under various configurations. Figure 1 shows schematically the j
combinations tested and the resulting CPM the detector registered. The test results show a count rate of 27+5 CPM when one or two Boral sheets were present between the source and detector compared to 210+15 CPM when i
no Boral is present. This high degree of separability between acceptable and non-acceptable results taake this test more than adequate to demonstrate j
the presence of the required amount of Boral. All tests were performed i
in air usir, ike same center to center spacing as the actual racks i
incorporated. Both ends of the model cavities are open and can be visually inspected as to the contents. Boral is visually distinct from aluminum in
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cross-section.
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III. ON-SITE INSPECTION 3
i All the new spent fuel racks will be inspected using this technique before installation in the spent fuel pool. An outline of the QA program that will be instituted for the in-situ inspection program is shown in Table 1.
All standard health physics precautions and procedures will be ir.plemented during the testing.
l The inspection program Yankee has outlined herein will verify the presence of 50 percent of the poison material in the necessary configuration to ensure Keff <.95.
We trust this will satisfy your requirements, however, if any questions arise feel free to call us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY D. E. Vandenburgh Vice President TMC/kg f
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r jggglgpgpy gggggg {jfg l-FIGURE 1 PRELIIIINARY IN-SITU TESTI.NG
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a Aluminum vs.
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CPM: 210+15 T
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l b Aluminum vs.
Boral CPM:
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Boral vs.
Boral Not to Scale CPM: 2715 l-
__.______ _ Boral Aluminum P002 ORIGINAL 9-L e_
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pgubi0ly UDC W Ol6 TABLE I T
M OUTLIriE~ 0F OA PROGRAM FOR c50$$
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- EVERY CAVITY WILL BE INSPECTED TO ENSURE THE PlIESENCE OF
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BORAL IN EACH DIRECTION.
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ALL DETECTOR READINGS AND' CORRESPONDING' CAVITY SERIAL-
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NUF3ERS WILL BE RECORDED.
- INDI'VIDUAL SIDES OF EACH CAVITY WILL BE ACCEPTED OR REJECTED 2
BASED ON ITS DETECTOR READING COMPARED.T0 STANDARD READING f
ESTABLISHED BY MODELS.
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AT PREDETERMINED INTERVALS THE ACCEPTABLE STANDARD DETECTOR READIiiG WILL BE REVERIFIED BY USING~MODELS.
- IF SIGNIFICANT DEVIATION FROM STANDARD READING IS FOUND j
DURING CALIBRATI0tl CHECL ALL PREVIOUS CAVITIES WILL BE RE-INSPECTED UP TO LAST CHECK USli1G CORRECTED EQUIPMENT.
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- ALL TESTING _WILL BE DONE IN ACCORDANCE WITH WRITTEN APPROVED PROCEDURES.
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- SION DOCKET NUMDE R M.i U.S. NUCLL AR f tLGUL ATOR Y COV 50-29 i
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NRC DfSTRIBUTION rOR PART 50 DOCKEY MATERI AL To:
NRC FHOM: YAEC DATE OF DOCUMENT 11-17-76 Westborough, Mass. 01581 D' ATE RECCiv5 076 D.E. Vandenburgh 11-2
[2LE TTE R O N OTO RIZ E D, PROP INPUT FORM NUMDER OF COPIES RECEIVE D
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