L-MT-08-041, Extended Power Uprate: Acceptance Review Supplemental Information Package 4
| ML081550640 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 06/03/2008 |
| From: | O'Connor T Nuclear Management Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-MT-08-041, TAC MD8398 | |
| Download: ML081550640 (44) | |
Text
Monticello Nuclear Generatinq Plant Operated by Nuclear Management Company, LLC June 3,2008 L-MT-08-041 10 CFR 50.90 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket 50-263 Renewed Facility Operating License License No. DPR-22 Monticello Extended Power Uprate (USNRC TAC MD8398):
Acceptance Review Supplemental lnformation Packaae 4
References:
- 1) NMC Letter to USNRC, "License Amendment Request: Extended Power Uprate,"
dated March 31,2008
- 2) NMC Letter to USNRC, "Monticello Extended Power Uprate (USNRC TAC MD8398): Acceptance Review Supplement Regarding Radiological Analysis,
dated May 20,2008
- 3) NMC Letter to USNRC, "Monticello Extended Power Uprate (USNRC TAC MD8398): Acceptance Review Supplemental Information," dated May 28, 2008
- 4) NMC Letter to USNRC, "Monticello Extended Power Uprate (USNRC TAC MD8398): Acceptance Review Supplemental lnformation Package 3," dated May 30,2008 Pursuant to 10 CFR 50.90, Nuclear Management Company, LLC (NMC), requested in Reference 1 approval of amendments to the Monticello Nuclear Generating Plant (MNGP) Renewed Operating License (OL) and Technical Specifications (TS) to increase the maximum power level authorized from 1775 megawatts thermal (MWt) to 1870 MWt, an approximate five percent increase in the current licensed thermal power (CLTP). The proposed request for Extended Power Uprate (EPU) represents an increase of approximately 12 percent above the Original Licensed Thermal Power (OLTP). The Monticello EPU application was supplemented on May 20, 2008, May 28,2008, and May 30,2008 by References 2,3, and 4.
In a teleconference held May 19, 2008, the NRC staff indicated that additional information would be necessary for the Reactor Inspection Branch to complete the acceptance review of the Monticello EPU license amendment request (LAR). The questions were formalized and emailed to NMC on May 20, 2008.
2807 West County Road 75 8 Monticello, Minnesota 55362-9637 Telephone: 763.295.5151 8 Fax: 763.295.1454
Document Control Desk Page 2 contains the questions and responses to the Reactor Inspection Branch.
NMC has reviewed the No Significant Hazards Consideration and the Environmental Consideration submitted with Reference 1 relative to the enclosed supplemental information. NMC has determined that there are no changes required to either of these sections of Reference 1.
Additionally, NMC received the following question from the Instrument and Control Branch (EICB) by email on May 22,2008:
"Based on this review, I find that licensee need to supplement information in their submittal for instrument setpoint methodology in accordance with the staff guidance provided in RIS 2006-17. Licensee in their submittal has been using the information which was previously approved by the staff. However, the staff has issued additional guidance on meeting 10CFR50.36 in RIS 2006-17 and no longer relying on TSTF -493."
Following a clarifying call on May 27, 2008, NMC committed to respond to the above ElCB question within 30 days of the clarifying teleconference (by June 26, 2008).
Commitment Summarv This letter makes one new commitment:
NMC commits to respond to the EICB question above regarding RIS 2006-017 by June 26, 2008.
I declare under penal& of perjury that the foregoing is true and correct.
' Timy J. OJConnor Site Ice President, Monticello Nuclear Generating Plant Nuclear Management Company, LLC cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC Minnesota Department of Commerce Enclosure to L-MT-08-041 Reactor Inspection Branch Questions and Responses NRC Statement: Section 2.10, Health Physics of the PUSAR describes the onsite and off-site radiation levels, normal and post-operation radiation levels. To evaluate Section 2.10, the acceptance criteria for occupational and public radiation doses are based on 10 CFR Part 20, GDC 19, and 40 CFR Part 190. To perform the health physics review of the EPU application, the following supplemental information is needed.
Onsite Radiation Levels NRC Question 1)
Provide the radiation levels prior to EPU and at EPU for the areas described in Table 2.10-1 and 2.10-2. Describe the methodology used to determine EPU radiation levels.
Tables 2.10- 1 and 2.10-2 of the PUSAR summarize the changes in area radiation levels at EPU.
Further details are provided in this enclosure.
Definitions of Radiation Zones used in the following tables can be interpreted as follows:
Access to this area is limited, but can be obtained through controlled doors.
Page 1 of 41 Page 2 of 41 Volume 1
2 3
4 5
Table Volume Description RHR and Core Spray Pump Room, Division I
RHR and Core Spray Pump Room, Division I Stairway RHR and Core Spray Pump Room, Division I1 RHR and Core Spray Pump Room, Division 11 Stairway RCIC Room Fire Zone Ill B V1B IU 1 A IV 1 A IIVl C Environmental B.1.4 B. 1.4 B. 1.4 B.1.4 B.1.3 1-Reactor Operating mrem/hr 2 - 3 5 120 - 160 Near HX Not surveyed 5 - 40 20 - 50 Near HX Not surveyed Not surveyed Predicted EPU Radiation Effect at Power Increase by13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by up to a factor of 11.3 (1 130%
when system shutdown.
No change during system operat ion.
Building Radiation Zone C
C C
C C
Predicted EPU Shutdown Dose Effect Increase by 1 3%
Increase by 1 3 %
Increase by 13%
Increase by 1 3 %
Increase by up to a factor of 1 1.3 (1 130%)
CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Page 3 of 41 Table Volume Description Reactor Bldg Elevation 896' Equipment and Floor Drain Tank CRD Pump Room HPCI Room Suppression Pool Area -
Northeast Suppression Pool Area -
Southeast Suppression Pool Area -
Southwest Volume 6
7 8
9 10 11 Predicted EPU Shutdown Dose Effect Increase by 1 3 %
Increase by 13 %
Increase by up to a factor of 1 1.3 (1 130%)
Increase by 13%
Increase by 1 3 %
Increase by 13%
1-Reactor CLTP Operating mrem/hr 0.5 - 20 40 - 100 Near Tanks Not surveyed 0.5 - 3 5-50 5-30 5 - 60 Fire Zone IT/ 1 D IU2C II/ 1 E IV/ 1 F IV/ 1 F N / l F Building Radiation Zone F
C D
F F
F Environmental Specification B. 1.2 B.l.10 B. 1.2 B. 1.6 B.1.6 i
B. 1.6 CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Predicted EPU Radiation Effect at Power Increase by 13%
Increase by 13%
Increase by up to a factor of 11.3
(
O%)
when system shutdown.
No change during system operation.
Increase by 13%
Increase by 13%
Increase by 13%
Page 4 of 41 Volume 12 13 14 15 16 17 18 19 Table Votume Description Suppression Pool Area -
Northwest East Shutdown Cooling Room B.1.9 CRD Hydraulic Control Unit Area - East 935' Elevation TIP Room Steam Chase TIP Drive Room CRD Hydraulic Control Unit Area and HVAC Areas -
NW 935' El CST Pump Transfer D W Equip Hatch Entrance Areas
- SW 935' El Fire Zone W/lF V2G I/2B I/2E IU2F IIU2A IV2C IIl2C 1-Reactor CLTP Operating mrem/hr 5-30 0.5 - 20 1 - 6 3 - 60 1-50 500 - 2000 In steam chase 25 - 800 in airlock 1 - 4 1-55 1 - 4 Environmental B. 1.6 B.1.8 B.1.9 B.1.9 B.l.10 B.1.12 Building Radiation Zone F
D' F
B B
CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed 1-2 Not surveyed Not surveyed Not surveyed Predicted Radiation Effect at Power Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
No change Increase by 13%
Increase by 13%
Increase by 13%
Predicted EPU Shutdown Dose Effect Increase by 13%
Increase by 1 3 %
Increase by 13 %
Increase by 1 3 %
Increase by 1 3 %
Increase by 13%
Increase by 13%
Page 5 of 4 1 Volume 20 I
21 22 23 24 25 26 27 Fire Zone IU2H I/3 B V3B I/3 B U3B L/3 B V/3 A IV3D Environmental Specification B. 1.8 B. 1.14 B.1.14 B.1.14 Recirc B.1.15 and B.1.23 Table Volume Description West Shutdown Cooling Room 21 U3B B.1.14 PIPE Chase 974' Pipe Chase 974' MCC and Standby Liquid Control System Area - East 962' E 1 Contaminated Tool Storage -
East 962' El MG Set Airlock 962' North of Reactor Shield Wall Reactor Recirculation Pumps MG Set Room Cooling Water Pump and Chiller Area -
West 962' El 1-Reactor CLTP Operating mrem/hr 1 - 3 0 1-30 1
1 surve ed Not I
1 - 4 1 - 5 2-30 Building Radiation Zone D'
B B
D B
B B
B CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Predicted EPU Radiation Effect at Power Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Predicted EPU Shutdown Dose Effect Increase by 1 3 %
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 1 3 %
Increase by 13%
Increase by 13%
Values expected to remain bounded by 2.78E+04 Rad TID at locations of EQ equipment values expected to remain bounded by 1.39E+04 Rad TID at locations of EQ equipment Values expected to remain bounded by 5.55E+05 Rad TID at locations of EQ equipment Values expected to remain bounded by 1.53E+O6 Rad TID at locations of EQ equipment Values expected to remain bounded by 1.1 1E+06 Rad TID at locations of EQ equipment Page 6 of 41 Predicted EPU Shutdown Dose Effect Increase by 1 3 %
Increase by 1 3 %
Increase by 1 3 %
Increase by 1 3 %
Increase by 13 %
Increase by 1 3%
Increase by 13%
Predicted EPU Radiation Effect at Power Increase by 1 3 % ~
Increase by 1 3%3 Increase by 1 3 %4 Increase by 1 3 % ~
Increase by 13 %'
Increase by 13%
Increase 13%
by CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Building Radiation Zone E
F F
F F
B B
1-Reactor CLTP Operating m rem/hr 40 20 80 2200 1600 1 - 3 1 - 6 Table Volume Description RWCU Pump Room B and Hallway RWCU Pump Room A RWCU Heat Exchanger Area RWCU Area Behind FIX Exchanger RWCU Isolation Valve Room MCC and Instrument Rack C-55 Area CGCS-A Recombiner Area Environmental Specification B.1.5 B. 1.5 B.1-5 B.1.5 B. 1.5 B.1.13 B.1.18 Volume 28 29 30 3 1 32 33 34 Fire Zone IV3D IV3D II/3D II/3 D IU3 D 1113 C U4A Page 7 of 4 1 Volume 35 36 37 38 39 40 41 42 Table Volume Description Cooling Water Heat Exchanger and CGCS-B Recombiner Area Standby Gas Treatment System B -
Train Room Standby Gas Treatment System Fan Room Standby Gas Treatment System Airlock Standby Gas Treatment System A -
Train Area Reactor Plenum Room Reactor Recirculation MG Set Fan Room Corridor Outside Main Exhaust Plenum Fire Zone V4B V4D V4D V4D V4D I/4E Vl3A V4C 1-Reactor CLTP Operating mrem/hr 1 - 4 I
1 1
1 1
I 1
Environmental Specification B.l.17 B.1.21 B.1.21 B.1.21 B.1.21 B.1.16 B.1.16 B.1.16 Building Radiation Zone B
F F
D F
C A
B CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Predicted EPU Radiation Effect at Power Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Predicted EPU Shutdown Dose Effect Increase by 13%
Increase by 1 3 %
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 1 3%
Increase by 1 3 %
Table 1-Reactor Building 1
1 CLTP
/Predicted I Volume 43 Fire Zone 44 Increase by 13%
Increase by 13%
I/5C 45 46 47 48 49 Increase by 1 3 %
Environmental Specification I/5A Increase by 13%
B.1.19 I/5B I/5B 115B I/6 DRYWEL L
Increase by 13%
Description B. 1.20 Page 8 of 4 1 Skimmer Surge Tank and Fuel Pool Pumps B.1.19 B. 1.19 B.1.19 B.l.l i
'ILTP Operating mremlhr Area Snubber Rebuild and Decontaminatio
- 500 n Area Northeast Stairway 1001' El Contaminated Equipment Storage Area Northwest Stairway 1001' El Refueling Floor 1 027' El Drywell Radiation Zone 1 - 5 C
1 - 2 1 - 6 Not surveyed 0.2 - 7 Not surveyed Shutdown Dose rate from annual B
survey Not surveyed B
C C
B F
EPU Radiation Effect at Power Not surveyed Predicted EPU Shutdown Dose Effect Increase by 13%
Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 13%
Increase by 1 3 %
Page 9 of 4 1 Predicted EPU Shutdown Dose Effect No change Increase by up to factor of 11 -3 (1 130%)
Increase by up to factor of 1 1.3 (1 130%)
No change No change No change Predicted EPU Radiation Effect at Power No change Increase by up to factor of 11.3 (1 130%)
Increase by up to factor of 11.3 (1 130%)
No change No change No change Building Radiation Zone A
A A
A A
A CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Volume Description Motor Control Center B-3 3A
& B, and B-12 Turbine Building Southeast Comer near MCC B-33 Lube Oil Reservoir and Reactor Feed Pump Area Lube Oil Storage Tank Room Turbine Building Corridor Northeast 91 1' El Water Box Scavenging System Area Environmental Specification B.1.24 B. 1.24 B. 1.24 B. 1.24 B. 1.24 B.1.24 Volume 1
2 3
4 5
6 Table 2 - Turbine CLTP Operating Mrem/hr 1
1 1
1 1 - 2 1
Fire Zone IW13C IXII 3C W13B IX/13A IW16 IX/ 16 Table 2 - Turbine Building CLTP 1
Radiation
[
CLTP 1 Predicted EPU 1 Volume 7
Page 10 of 41 Fire Zone 8
9 10 11 12 13 IXIl2A Environmental Specification W12A IX/ 12A X/12B X/12D X/ 12D Xl12E Turbine BuiIding Sump &
MCC B-3 1 Volume Description B. 1.24 8.1.24 B. 1.24
'24 B. 1.24 survey Not surveyed Operating Mrem/hr 4 KV and Load Center Division A East 4 KV and Load Center Division A West Hydrogen Seal Oil Unit and Condensate Pump Area Mechanical Vacuum Pump Area Condensate Backwash -
Receiving Tank Area Air Ejector Room No change Zone No change 1
1 1
1 - 5 1 - lo 30 5 - 3 0 2 - 1500 Shutdown Dose rate from annual A
A E
F F
Radiation Effect at Power Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed 0.2 - 3 Predicted EPU Shutdown Dose Effect No change No change No change No change No change Increase by 25% to 33%
No change No change No change No change No change Increase by up to a factor of 1 1.3 (1 130%)
Page 11 of 41 Volume 14 15 16 17 18 19 20 21 Table 2 - Turbine CLTP Operating Mrem/h r 5 - 1800 1
1 1
1 1
Not surveyed 1
Environmental Specification B. 1.24 B. 1.24 B. 1.24 B. 1.24 B. 1.24 B. 1.23 B. 1.23 B. 1.23 Fire Zone W12C W 1 6 W23A IX123A XXIIL/24 IXl23A IX/13C IXl13B IX/ 1 6 CLTP Shutdown Dose rate from annual survey 0.2 - 2 Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Building Radiation Zone F
A A
A A
A A
B Volume Description Turbine Basement Condenser Area Pipe Tunnel to Intake Intake Entry Area Intake Structure Pump Room Circ Water Pump Area Turbine Building Southeast Stairway from 911'to 931' El Turbine Building 93 1 '
El Vent Chase Turbine Building Corridor Northwest 93 1' El Predicted EPU Radiation Effect at Power Steam areas increase by 9%
Condensate areas increase by up to 11.3 (1 130%) times No change No change No change No change No change No change No change Predicted EPU Shutdown Dose Effect Increase by up to a factor of 1 1.3 (1 130%)
No change No change No change No change No change No change No change Page 12 of 41 Volume 22 23 24 25 26 27 28 Environmental Specification B. 1.23 B. 1.23 B. 1.23 B. 1.23 B. 1.23 Fire Zone IX/12A XI14B XIV19B IX/19C XIV 19A XI11 19A XIV20 Volume Description Turbine Building Northwest Stairway from 93 1' to 951' El Valve Operating Gallery and Condensate Demin Panels Area Motor Control Center B-42 A&B, and B-43 A&B FW Pipe &
Cable Tray Penetration Room Water Treatment Area South Water Treatment Area North Auxiliary Boiler Room Table 2 - Turbine CLTP Operating Mremlhr 1
1 1
1 1
CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Building Radiation Zone A
A A
A A
Predicted EPU Radiation Effect at Power No change No change No change Increase by up to a factor of 11.3 (1 130%)
No change No change No change Predicted EPU Shutdown Dose Effect No change No change No change Increase by up to a factor of 1 1.3 (1 130%)
No change No change No change Page 13 of 41 Volume 29 30 3 1 32 33 34 35 36 37 Volume Description East Electrical Equipment Room and 13 EDG Hot Machine Shop Oil Storage Room Turbine Building Corridor Southeast Comer 93 1 '
EI Cable Chase 941' El No. 11 Diesel Generator Room No. 1 1 Diesel Generator Room Entry Area No. 12 Diesel Generator Room Stator Water Cooling Area Fire Zone XIU3 4 XIU18A XIV 1 8B IW16 IX/ 1 6 XIV/lSB XIV/l5B XIIU15A XIV 14A Table 2 - Turbine CLTP Operating Mrem/hr 1
1 1
1 1
1 1
1 I
Building Radiation Zone A
A A
A A
A A
A A
Environmental Specification B. 1.23 B. 1.23 B. 1.23 B.1.23 B. 1.23 B. 1.23 B + l '23 B. 1.23 B. 1.23 CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Predicted EPU Radiation Effect at Power No change No change No change No change No change No change No change No change No change Predicted EPU Shutdown Dose Effect No change No change No change No change No change No change No change No change No change Page 14 of 41 Volume 38 39 40 41 42 43 44 Fire Zone XI11 1 4A XIII 14A XI 14C XI3 0 XI3 0 1x16 XI3 0 Environmental Specification B. 1.23 B. 1.23 B. 1.23 B. 1.22 B. 1.22 B. 1.23 B. 1.22 Volume Description 4KV and Load Center Division B East 4KV and Load Center Division B West Turbine Building Railroad Car Shelter Pass System Area Turbine Volume from 951'to 961' El Hallway to No. 11 Diesel Generator Entry Area Turbine Volume from 961' El to 1004' El Table 2 - Turbine CLTP Operating Mremlhr 1
1 1-2 1-3 1 - 1000 10 - 3000 Not surveyed 1 - 1000 10 - 3000 Building Radiation Zone A
A B
C F
A F
CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed 1-5 Not surveyed 1-5 Predicted EPU Radiation Effect at Power No change No change No change No change Increase by 2%
to 9%
No change h-lcrease by 2%
to 9%
Predicted EPU Shutdown Dose Effect No change No change No change No change Increase by up to a factor of 1 1.3 (1 130%)
No change Increase by up to a factor of 1 1.3 (1 130%)
Table 3 - Control Room Page 15 of 41 Area Description Control Room Area Description Recombiner Building Roof Diesel Generator Building Roof Breaker Room Roof Turbine Building Addition Roof Hot Shop Roof Turbine Building Roof Non-1 E Elec Room Roof Heating Boiler Bldg Roof EFT Roof Admin Building Roof Reactor Building Roof CLTP Operating mremlhr
<0.2 CLTP Operating mremlhr 1 - 1.8 1.2-8 0.4 - 4 6-60 8-42 16-180
.6 -.2 1.6 - 1.8 0.6 - 8 0.2 - 60 0.2 - 14 Radiation Zone A
Table 4 -
Radiation Zone CLTP Shutdown Dose rate from annual survey
<0.2 Protected Area CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Predicted EPU Radiation Effect at Power No change and Building Roofs Predicted EPU Radiation Effect at Power Increase by 10%
Increase by 10%
Increase by 10%
Increase by 10%
Increase by 10%
Increase by 10%
Increase by 10%
Increase by 10%
Increase by 10%
Increase by 13%
Increase by 13%
Predicted EPU Shutdown Dose Effect No change Predicted EPU Shutdown Dose Effect No change No change No change No change No change No change No change No change No change No change No change Area Description Protected Area South of Radwaste Building Protected Area West of Reactor Building Protected Area East of Admin Building Protected Area Northeast of Turbine Table 4 - Pr Operating mremlhr Building Protected 1 Area 1 c0.2 - 3.4 1 C
of Turbine Building Protected Turbine Building tected Area CLTP Shutdown Dose rate from annual survey Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed Not surveyed nd Building. Roofs Predicted EPU Radiation Effect at Power No change No change No change No change No change Increase by 10%
Predicted EPU Shutdown Dose Effect No change No change No change No change No change No change Page 16 of 41 Page 17 of41 Item 1
2 Table 5 - Evaluations Subject Plant Shielding Design Plant shielding design was based on conservative specifications of radioactivity concentrations in coolant.
Operating Dose - Reactor Building Dose rates in the reactor building are estimated to increase by 13% during power operation at EPU.
Dose rates close to the steam chase are estimated to be unchanged at EPU.
and Methodology Description/Basis USAR 12.3.1.6 described the design bases for shielding. "The offgas system shielding is based on a stack release rate of 260,000 pCi/sec. Reactor water fission product concentrations and activated corrosion products were assumed to be the maximum values expected: 8.0 pCi/cc, and 0.07 pCi/cc, respectively." These design criteria are not approached during normal plant operation and will remain very conservative at EPU.
The primary source of operating radiation dose in the reactor building is due to core gamma and neutron radiation from the reactor. This source increases at EPU in direct proportion to the increase in thermal power production. EPU power is 2004 MWt, and CLTP power is 1775 MWt, therefore dose rates were estimated by scaling existing dose rates by 13%.
Areas near the steam chase receive dose due to the N-16 source in steam piping. The production rate of N-16 increases in proportion to the increase in thermal power. However, the increase in steam flow rate also increases in proportion to the increase in thermal power. As a result the concentration of N-16 in steam is essentially unchanged at EPU conditions. Steam velocity also increases, but since the steam chase is close to the reactor there is no significant change in transit time for decay so dose rates in the vicinity of the steam chase will remain about the same as at current operating conditions.
The TIP system area will likely experience an increase in observed radiation levels due to an increase in the activation of the detector's head and cable as a result of the increase in Page 18 of 41 and Methodology Description/Basis reactor power. This area is designated as a Radiation Zone F
(> 100 mrernh) and is normally inaccessible. Since this area is normally inaccessible, the increase in observed normal radiation levels does not impact plant personnel normal activities and the zone's normal radiation zoning designation is deemed acceptable for EPU implementation.
The Drywell area is designated as a Radiation Zone F (> 100 mremkr) and is normally inaccessible during power operations. As a result of the EPU, the Drywell radiation levels increase due to a 13% increase in reactor core operating sources. Since this area is normally inaccessible, the increase in observed normal radiation levels does not impact plant personnel normal activities and the zone's normal radiation zoning designation is deemed acceptable for EPU implementation.
Following reactor shutdown the Drywell dose rate is primarily a result of the core fission product source term in the reactor and activation and corrosion products deposited in various plant piping systems and components. Both of these sources will change in proportion to the increase in power level and are estimated to increase by about 1 3%
The primary source of radiation adjacent to the primary containment and inside the drywell is due to the core source term inventory at the time of shutdown. Following reactor shutdown, components activated by neutron radiation, fission products, and activated corrosion and wear products also become significant sources, especially when deposited in piping and equipment outside of the RPV. Both of these sources (core source term and activation products) will Item 3
4 Table 5 - Evaluations Subject Reactor Building - Drywell Operating and Shutdown Dose Shutdown Dose - Reactor Building Shutdown dose rates in the reactor building are estimated to increase by 13% following shutdown from EPU conditions.
Page 19 of 41 Item 5
Table 5 - Evaluations Subject Operating Dose - BOP Areas Dose rates in areas that are dominated by the N-16 source term are affected by changes in transit and residence time for steam transport. A Microsoft Excel spreadsheet was used to estimate these changes.
Dose rates in areas where N-16 has substantially decayed will be governed by increased deposition of coolant fission and activation products. In areas such as heater drains and condensate this is driven by up to a ten-fold increase in moisture carryover (MCO) and by up to a 13% increase in activation due to neutron flux increase in the core. Some areas could increase by up to a factor of 11.3 (1 130%).
These areas have low dose rates during plant operation so the impact of this increase on radiation dose to workers can be minimized by monitoring radiation levels and controlling access to areas. This is sort of dose management approach is driven by the ALARA principle and is already in use at MNGP.
See Tables l,2,3 and 4 above for estimates of changes to specific plant areas.
and Methodology DescriptiodBasis increase in direct proportion to the increase in thermal power.
Shutdown dose rates from these sources are estimated to increase by 13% compared to CLTP.
Dose rates during normal plant operation in areas exposed to reactor coolant and steam are primarily a function of N-16 concentration.
N-1 6 concentration in reactor steam is essentially unchanged as power increases due to dilution in the associated increased steam flow.
Increased steam flow rates reduce the transit time in steam piping. The reduction in transit time also reduces the time for decay of the N-16 source at any specific location. The result is increased dose rates in areas further downstream.
A series of evaluations were for various plant areas based on the effect of steam transit time and N-16. The estimates were made by scaling OLTP transit times to various components, first to CLTP and then to EPU conditions and then computing the difference in N-l 6 decay time to compute a change in radiation level.
The results show that areas closest to the reactor have little or no change in N-16 dose rate.
Steam areas of the plant show dose rate increase of up to 14%
at the exit of the # 14 FWH.
Radiation levels are expected to increase by 3 1% to 34% in the S JAE and Offgas system steam piping.
The dose rate due to N-16 entering the condenser increases by and Methodology Description/Basis about 9%.
N-16 dose in the condensate leaving the hotwell shows an increase of a factor of about 10, but since most of the N-1 6 will have decayed, this will not result in a significant increase in radiation levels. Due to significant holdup time in the condenser hotwell, nearly all N-16 will decay before it moves on to the condensate piping, demineralizers, and feedwater system. The net holdup time in the condenser hotwell at current hotwell control levels is a minimum of 2 1.5 half-lives of N-1 6. The dose rate in condensate and feedwater piping areas is more a result of deposition of activation and corrosion products than a result of N-16. As a result, radiation levels in these areas are predicted to be unaffected by N-16 changes at EPU.
Dose rates in BOP areas where the N-16 source has decayed result from deposition of fission products, and activated corrosion and wear products. These areas will see radiation dose increases determined by the increase in moisture carryover (up to a factor of 1 1.3 or 1 1 3 0%).
The results are summarized in Table 6 of this enclosure. The evaluation used the steam concentration of N-16 from the transit time scaling mentioned earlier in this item. However, since the final result is the ratio of the results of two different results based on the assumed steam concentration, the assumed concentration cancels out.
Shutdown dose rates in the balance of plant are a result of activation of corrosion and wear products and fission products with longer half-lives that are deposited in BOP piping and Item 6
Table 5 - Evaluations Subject Shutdown Dose - BOP Areas Shutdown dose rates due to activation and corrosion products will increase proportional to the power uprate -
Page 21 of 41 Item Table 5 - Evaluations Subject approximately 1 3%.
Shutdown dose rates will increase proportional to the assumed increase in moisture carryover.
Performance Assumption for MCO at EPU is 0.5%.
shutdown dose rates will increase by up to a factor of 10 as a result of moisture carryover.
The net change in shutdown dose rates in plant areas due to moisture carryover and deposition be up to O*
or an increase by a factor of 11.3 (1 130%).
See Tables 1,2, 3, and 4 of this enclosure for predictions of changes in BOP areas.
and Methodology Description/Basis equipment during plant operation. Short lived radioactivity decays before it can become significant shutdown dose concern.
The biggest impact in radioactivity deposition in balance of plant piping will be a result of the carryover of fission products and activated corrosion and wear products in reactor steam. Carryover allows soluble and non-soluble radioactive isotopes to reach BOP piping systems and equipment where it can build up over time until its decay rate matches its deposition rate. The time to achieve 95% of its maximum possible concentration for a given isotope is on the order of 4.5 half-lives. Most isotopes evaluated in ANSIIANS 18.1 will reach equilibrium in less than an operating cycle, but some long lived isotopes will take many years (e.g., Mn-54, Fe-55, Co-60, Ni-63, Sr-90, Ru-1 06, and Ce-144).
Fission Product Generation Rate Fission product generation rate will increase in proportion to reactor neutron flux which is proportional to the increase in EPU thermal power. Fission product Noble Gases will pass through the system and be exhausted through the Steam Jet Air Ejectors and Offgas system. Undecayed, gaseous fission product iodine will likewise be exhausted as a gas.
Fission product solids and decay products will also increase in proportion to thermal power but as solids these products tend to remain in the reactor vessel.
Corrosion Product Generation Rate Zinc injection, hydrogen water chemistry systems and coolant chemistry controls will continue to work to minimize Page 22 of 4 1 1
and Methodology DescriptionIBasis corrosion. Corrosion rates are not expected to change significantly at EPU conditions.
Erosion and Wear Products Generation Rate Generation of erosion or wear products is a function of flow velocity. While flow rates in power cycle systems increase at EPU conditions, the rates of erosion and wear are expected to remain low.
Operation of Condensate demineralizers and Reactor Water Cleanup demineralizers will act to reduce the changes in the concentration of corrosion and wear products in the coolant.
As a result, equilibrium concentration of erosion and wear products are assumed to remain about the same at EPU conditions.
Erosion/Corrosion Product Activation Rate The rate of activation of corrosion and wear products is therefore expected to increase proportionally to the increase in core neutron flux which will be proportional to the thermal power increase (about 1 3 %).
Deposition Rate The rate of deposition of radioactivity is a function of reactor power and fluid temperature and velocity. Increased steam, condensate and feedwater flow rates would be expected to reduce deposition rates roughly in proportion to the increase in flow rates. This will roughly offset the increased production rate of radioactivity.
Item Table 5 - Evaluations Subject Page 23 of 4 1 and Methodology Description/Basis Impact Summary The biggest impact in radioactivity deposition in balance of plant piping will be a result of the carryover of fission products and activated corrosion and wear products in reactor steam. Carryover allows soluble and non-soluble radioactive isotopes to reach BOP piping systems and equipment where it can build up over time until its decay rate matches its deposition rate. The time to achieve 95% of its maximum possible concentration for a given isotope is on the order of 4.5 half-lives. Most isotopes evaluated in ANSIIANS 1 8.1 will reach equilibrium in less than an operating cycle, but some long lived isotopes will take many years (e.g., Mn-54, Fe-55, Co-60, Ni-63, Sr-90, Ru-106, and Ce-144).
BOP areas currently have very low dose rates during plant shutdown so the impact of this increase on radiation dose to workers can be minimized by monitoring radiation levels and controlling access to areas. This sort of dose management approach is driven by the ALARA principle and is already in use at MNGP.
FiltrationIDemineralizer systems at MNGP include the Reactor Water Cleanup and Condensate Demineralizer systems. These system use mechanical and chemical filtration processes to remove particulates and chemically active contaminants from coolant. The levels of impurities including radioactive in the effluents are significantly reduced from levels in the influents, but neither of these processes removes 100% of the impurities from the fluid. Even though the radioactivity levels in effluents from these systems are significantly decreased they will change by a similar proportion as described for the influents as Item 7
Table 5 - Evaluations Subject Impact of FilterIDemineralizer Systems on Radiation Levels Page 24 of 4 1 and Methodology Description/Basis described in this evaluation.
To accommodate increased flowrates, condensate demineralizers at MNGP will be replaced as part of the modifications to support EPU. It is assumed that the new equipment will be selected and sized to support mechanical and chemical removal efficiencies equivalent to the current system performance at CLTP.
A conservative RWCU system flowrate that does not maintain the current assumption of 1 % of the rated feedwater flowrate was used. This results in conservatively higher estimates of coolant source term concentrations. The results indicate that the assumption that the coolant source terms increase in proportion to the power increase is conservative.
The volume of solid and liquid radwaste processed will increase at EPU conditions. The bulk of this increase will come from condensate demineralizer and RWCU demineralizer resin wastes.
Dose rates in radwaste areas are a function of how much waste material is present. This source can be controlled by the use of shielding or frequency of transportation for disposal.
Therefore, there is no clear correlation between dose rates in radwaste processing areas and reactor power level.
The Main Control Room is designated as a Radiation Zone A (2 0.5 rnrern/hr) allowing for uncontrolled access and unlimited occupancy. As reflected in radiation survey data, the normal operating radiation level in the Main Control Room is currently less than 0.2 mrernlhr. This area is well shielded Item 8
9 Table 5 - Evaluations Subject Doses in Radioactive Waste Processing and Storage Areas Control Room Page 25 of 41 and Methodology Description/Basis from the normal operation radiation sources that would be affected by the EPU. With the implementation of the EPU, the observed area dose rates may increase in proportion to the change in power (approx 13%); however, due to the low radiation levels in the Control Room, this increase is considered to be negligible. EPU will not result in a change to the Main Control Room normal radiation zone designation for personnel access. Equipment in the control room will not have any significant change to the total integrated radiation dose from normal operation that is currently evaluated for the EQ program.
The most significant source of radiation dose rates for these areas is the N-16 source from the turbine building. As described above. The N-16 source concentration in steam leaving the reactor does not change significantly at EPU conditions.
Due to shorter transit times, the concentration of N-16 hrther downstream in steam piping, turbines, and heaters will be higher than at present. This will increase dose rates on the turbine op deck and shine from the turbine building.
Based on the estimates of N-16 dose rates in Table 6 below it can be seen that the dose rates at the HP turbine increase about 3%: the LP turbine about 9% and the # 15 Feedwater Heater about 17% on average. Therefore, reasonable bounding estimate is that radiation levels driven by shine will increase by about 10%.
Item 10 Table 5 - Evaluations Subject Protected area, Building Roofs, Sky Shine and Site perimeter Table 6 - Evaluation of N-16 Dose Rates TRANSIT Time Time OLTP N-16 OLTP Flow OLTP Tkne CLTP Flow CLTP N-I6 CLTP Time EPU Flow EPU N-16 EPU
% Change EPU CA-67-086 sec micro-Cilgm lblhr sec lblhr micro-Ciigm sec lblhr micro-Cilgm Vessel to Steam stop 0
0 6.15Et01 6.78Et06 0.00 7.26E+06 6.1 1 Et01 0.00 8.32Et06 6.00Et01
-1.70%
2.05321 2.05321 5.04Et01 6.44Et06 1.95 6.77E+06 5.05Et01 1.59 8.32E+06 5.14f +01 1.84%
MSL Steam Chase to Stop Valves 0.49 2.05321 5.04Et01 6.44Et06 1.95 6.77+06 5.05Et01 1.59 8.32E+06 5.14Et01 1.84%
HP Turbine 1.I2 2.68321 4.74Et01 6.44Et06 2.55 6.77EN6 4.76Et01 2.08 8.32E+06 4.91EtOl 2.95%
1.14 2.70321 4.73E+01 6.44E+06 2.57 6.77ENS 4.76E+01 2.09 8.32E+06 4,90E+01 2.99%
Moisture Separator 1.53 3.09321 4.55E+01 6.04Et06 2.96 6.32EN6 4.58Et01 2.41 7.74Et06 4.75Et01 3.62%
3.44 5.00321 3.78E+01 6.04Et06 4.78 6.32E+06 3.84Et01 3.91 7.74Et06 4.1 1 Et01 7,04%
LP Turbine 4.04 5.60321 3.57EN1 5.40Et06 5.34 5.67E-1.06 3.63Et01 4.33 7.00E+06 3.94Et01 8.45%
4.07 5.63321 3.56E+01 5.40Et06 5.37 5.67E+06 3.62Et01 4.35 7.00Et06 3.93Et01 8.50%
Condenser 4.07 5.63321 3.56Et01 6.43Et06 5.36 6.76EN6 3.63Et01 4.35 8.34Et06 3.93Et01 8.48%
4.1 1 5.67321 3.54EN1 6.43Et06 5.40 6.76E96 3.61E+01 4.38 8.34E+06 3.92EN1 8.55%
- I5 FWH 2.18 3.74321 4.28E+01 3.63Et05 3.36 4.05E45 4.41 Et01 2.55 5.33E+05 4.68E41 6.30%
6.81 8.37321 2.73E+01 3.63Et05 7.51 4.05E+05 2.94Et01 5.71 5.33E+05 3.45Et01 17.10%
- I4 FWH 4.88 6.44321 3.29E+01 7.89Et05 6.17 8.25E+05 3.35Et01 5.19 9.79Et05 3.62E301 8.07%
8.48 10.04321 2.32E+01 7.89Et05 9.61 8.25E+05 2.40Et01 8.09 9.79Et05 2.73+01 13.94%
SJAE Steam 0
1.56321 5.29E+01 7.00Et03 1.33 8.20E+03 5.36Et01 0.90 1.22Et04 5.50Et01 2.58%
9.1 10.66321 2.18Et01 7.00Et03 9,10 8.20EN3 2.52Et01 6.12 1.22Et04 3,31E+01 31.40%
OG 4.1 1 5.67321 2.29Et05 8.00E+02 5.67 8.00E42 2.45Et05 5.67 8.00E42 3.28Et05 33.76%
0.8 factor described in USAR 12.3.2.2.2 121 122.56321 2.66E+00 8.00Et02 122.56 8.00E+02 2.45Et05 122.568.00Et02 3.28Et05 33.76%
Hotwell 4.1 1 5.67321 7.12E+00 6.43Et06 5.40 6,76E+06 7.23Et00 4.38 8.34E+06 7.85E+00 8.55%
0.2 factor described in USAR 12.3.2.2.2 202.75 25.02 1.08E+00 6.43Et06 182.38 6.76E+06 2.44E-07 158.13 8.34Et06 2.53E-06 938.50%
Rerate Heat Balance Rerate Heat Balance Heat Balance AA06-291 RO Page 26 of 41 NRC Question
- 2) Describe the radiation surveys to be performed as part of the startup testing plan.
NMC Res~onse The radiation surveys will be performed as part of STP-5, which is described in Tables 1 and 2 of the Monticello EPU LAR, Enclosure 9, Startup Test Plan. EPU Test 2 (Table 8 on next page) will be the control for Radiation Surveys.
Item 1
2 3
Page 27 of 4 1 Table 7 Subject Radiation Surveys Site Boundary and Protected Area Radiation Surveys Office Areas and Facilities Radiation Surveys
- Radiation Surveys Recommendations from Evaluation 1 Perform plant radiation surveys during power ascension testing and at EPU to confirm predicted radiation dose rates.
2 Perform post-shutdown plant radiation surveys following operation at increased power levels to confirm predicted shutdown dose rates.
As part of power ascension testing perform detailed radiation surveys at protected area and site boundaries to identify any areas with radiation level increases due to possible radiation streaming. This monitoring will help prevent potential issues with offsite dose rates before regulatory limits could be exceeded.
As part of power ascension testing perform detailed radiation surveys at site office areas and facilities that can be occupied by members of the public or workers not subject to occupational exposure limits to identify any areas with radiation level increases due to possible radiation streaming. This monitoring will help prevent potential issues with dose rates before regulatory limits could be exceeded.
Page 28 of 41 Item 1
2 3
4 5
6 Subject Purpose Applicability Description Test Data Acquisition Test and Test Conditions Acceptance Criteria Table 8 - Test Number 2, Radiation Measurements Description Monitor radiation at the EPU conditions to assure that personnel exposures are maintained ALARA, radiation survey maps are accurate, and radiation zones are properly posted.
Applies to both mid-cycle on-line and post-refueling outage EPU implementation phases.
At selected EPU power levels, gamma dose rate measurements and, where appropriate, neutron dose rate measurements will be made at specific limiting locations throughout the plant to assess the impact of the uprate on actual plant area dose rates. USAR radiation zones will be monitored for any required changes.
Within the EPU power ascension test procedure or the governing test schedule, add steps, at selected EPU power levels, to conduct radiation surveys of those areas expected to experience an increase in radiation dose rates.
Test:
- 1. Measure radiation levels at selected locations throughout the plant Test Conditions:
A. 2100% CLTP up to maximum EPU power.
The radiation doses of plant origin and the occupancy times of personnel in radiation zones shall be controlled consistent with the guidelines of the standards for protection against radiation as outlined in 10CFR20, "Standards for Protection Against Radiation".
NRC Question 3)
Describe the contribution and effects of hydrogen water chemistry (HWC) (N-16) to the radiation doses (both pre-EPU and post-EPU) to members of the public onsite.
NMC Response Page 29 of 41 Item 1
2 3
Table 9 - Effects Assumption The increase in skyshine dose rate at EPU conditions is driven by N-16.
HWC injection rate will be increased by approximately 14.8%
(the EPU increase in feedwater flow rate) to maintain feedwater hydrogen concentration at current levels.
The dose rate due to N-16 increases linearly with the increase in hydrogen injection rate.
of HWC Ref./Basis N-16 is the predominant radiation source in BWRs, especially in plants with HWC. N-16 production rate increases in proportion to the increase in thermal power (approximately 13%). At a constant HWC injection rate the feedwater hydrogen concentration entering the reactor would decrease slightly. However, this effect is offset by the increase of radiolysis which produces free hydrogen from the reactor coolant. The increase in steam flow at EPU (14.8%)
offsets this increased N-1 6 production by dilution. So N-1 6 concentration in steam exiting the RPV at EPU (without an increase in HWC Injection rate) would remain constant.
Increased steam flow rates decrease transit time for N-16 in steam to various points in the BOP. This reduction in transit time allows less time for decay of N-16 and results in increased radiation levels further downstream in steam piping and steam systems.
Reasonable assumption, based on design basis for HWC. No actual increase has been planned or identified at present.
EPRI Report NP-4621 (See Figure 1 below) shows the typical characteristic response of steam radiation levels with increasing hydrogen injection rate. MNGP radiation operating hydrogen injection levels place the plant in the upper region of this curve where it is conservative to predict a linear increase in radiation levels with increasing injection rate.
Figure 1 - Dose Rate as a Function of HWC Injection Rate (Typical) 0 10 20 30 40 50 60 NOMINAL HYDRCGM FLOW (SCFMI Figure 4-1.
Contributions to Dose Rate as a Function of Hydrogen Addition Page 30 of41 Page 31 of 41 Item 4
Table 9 - Effects Assumption Plant Skyshine from the Turbine of HWC Ref./Basis The primary source of skyshine is the N-16 gamma in reactor steam in the turbine building. The shine from piping and components above grade will only be attenuated by equipment materials, shielding and building materials. The skyshine dose for equipment below grade will be also be attenuated by the earth around the turbine building. In general the changes in the equipment above grade will be the most significant factor in skyshine although radiation scatter from other sources may be present. The equipment above grade includes steam piping, turbines, feedwater heaters, the upper portions of moisture separators and the transition between the turbines and condenser.
A conservative estimate of the impact of EPU on skyshine is based on the increase in N-16 dose as a function of increased injection rate times the change in dose due to changes in steam transit time.
Using 14.8% increase in feedwater flowrate to estimate increased hydrogen injection rate and the effect of transit time at the exit of the # 15 FWH (1 7.1 % increase in estimated dose rate) yields a maximum skyshine source dose rate increase of 34.4%
(1.148*1.171).
Page 32 of 41 Table 9 - Effects of HWC Item The 2006 Annual Radiological Operating Report for MNGP reported the results of radiation monitoring for the plant. The report stated:
"Ambient radiation was measured in the general area of the site boundary, at an outer ring 4 - 5 mi distant from the Plant, at special interest areas and at four control locations. The means were similar for both inner and outer rings (16.5 and 1 5.6 mRem19 1 days, respectively)....The mean for the control locations was 15.7 mRed91 days. Dose rates measured at the inner and outer ring locations were similar to those observed from 199 1 through 2005...No plant effect on ambient gamma radiation is indicated."
Tabular and graphical data is provided in Monticello EPU LAR,, Table 7.2.2-1 and Figure 7.2.2-1.
The conclusion in the report is that there is no plant effect on ambient gamma radiation. This would support an estimate that skyshine changes due to EPU will not have any impact on measured dose rates offsite.
The data shows a maximum difference between the inner and outer ring of 1.1 mrem for a quarter. If this is taken as a measure of skyshine it represents a maximum of 4.4 mrem per year at current conditions. Scaling this result by 34.4% is less than 6 rnrem /yr. This is considered a conservative upper bound for offsite dose to skyshine at EPU conditions.
Assumption Ref./Basis Also see the location specific dose information and predictions for onsite areas described for NRC Question 1 above. These results included N-16 effects. A discussion of methods used to predict N-16 changes in plant areas due to the transit time effects is included as Item 5 in the table of evaluations for BOP areas. Table 6 in that response shows the results for specific plant areas.
Table 9 - Effects of HWC Page 33 of 41 Item Assumption Ref./Basis The average exposure due to gaseous emissions and liquid effluents to an individual are less than a total of 1 mrem per year.
Adding this to the skyshine estimate of 6 mrem/yr is a total of 7 mrem. As a result it is concluded that the maximum potential dose to any member of the public will remain well within the 40 CFR 190 limit of 25 mremlyr.
Off-Site Radiation Levels NRC Question
- 4) Provide the dose value contributions for the primary sources of normal operation offsite doses (all effluent releases, gamma shine, storage and transfer of radioactive materials) to a member of the public at EPU. Describe the methodology to determine these doses.
NMC Response:
Plant history from annual reports from 2001 through 2006 can be found in the Monticello EPU LAR Enclosure 4, Tables 7.1.3-1 and 7.1.3-2.
The plant Gaseous Waste Management system was evaluated and concluded that:
- a. the increased off-gas flow rates at EPU are within the design capacity of the system,
- b. fission product holdup times in the compressed gas storage portion of the offgas system are not impacted.
There is, in fact, increased radiolysis production of offgas volumetric flow at EPU conditions proportional to the increase in power. There is also an increase in production rate of fission product and activation product gases at EPU proportional to the increase in power. The amount of air in leakage that adds to the offgas flow rate is determined by the physical condition of the condenser and is not impacted by the EPU. In 2003 and 2004, excessive air inleakage to the condenser at MNGP exceeded the capacity of the offgas Page 34 of 41 full cycle with the storage portion of the offgas system bypassed (Holdup time was essentially reduced to zero). However, the condition did not require the plant to shutdown and the offsite dose consequences remained a small fraction of regulatory dose limits.
This clearly demonstrates that there is significant operational margin to support operation at EPU conditions.
To summarize, increased offgas flowrates at EPU will reduce the actual holdup time.
However all increases in offgas volume flowrates remain within the design basis capacity of the offgas system and the offgas storage system.
Monticello EPU LAR Enclosure 4, Table 7.1.3-1 summarizes data reported by MNGP in the Annual Radioactive Effluent Release Reports and includes the Technical Specifications reporting dose limits for gaseous effluent releases. By examination it is clear that an increase of 12.9% in dose would remain a very small fraction of the reporting limits.
Monticello EPU LAR Enclosure 4, Table 7.1.3-2 summarizes data reported by MNGP in the Annual Radioactive Effluent Release Reports and includes the comparison to the regulatory dose limits for gaseous effluent releases from 10 CFR 50 Appendix I and 40 CFR 190. By examination it is clear that an increase of 12.9% in dose would remain a very small fraction of the regulatory limits.
Current environmental monitoring and effluent release reporting requirements remain adequate. Any unplanned gaseous release to the environment that exceeds two times the Offsite Dose Calculation Manual limit for 60 minutes or longer will result in declaration of an Unusual Event, activate the emergency planning organization, and initiate actions to protect the health and safety of the public. The ODCM setpoints are based on a release Page 35 of 41 Page 36 of41 supports a conclusion that EPU will have no significant impact on offsite dose from since January 1972 (USAR 9.2.3.1). The Liquid Radwaste Processing Systems will have an excess processing margin of about 45% at EPU conditions. Therefore the plant capability of maintaining a zero-discharge liquid effluent release policy is not impacted by operation at EPU.
The small volume and radioactivity of unplanned discharges is clearly demonstrated by the plant historical trends summarized in Attachment 1 Table 1. The potential dose consequences of these unplanned discharges are summarized in the historical trends in Tables 1 and 2. These tables include the Technical Specifications Reporting dose limits and the 10 CFR 50 Appendix I and 40 CFR 190 regulatory dose limits. By examination it is clear that the potential exposures to the public from liquid effluent releases have been a minute fraction of the regulatory limits.
Future unplanned releases could reflect the greater production rate of fission products and activation products at EPU. Current environmental monitoring and effluent release reporting requirements remain adequate. Any unplanned liquid release to the environment that exceeds two times the Offsite Dose Calculation Manual limit for 60 minutes or longer will result in declaration of an Unusual Event, activate the emergency planning organization. and initiate actions to protect the health and safety of the public. The ODCM setpoints are based on radioactivity concentrations that would result in a total dose of 500 mrem in one year if ingested continuously. ODCM-03-0 1 section 2.1 equipment materials, shielding and building materials. The skyshine dose for equipment below grade will be also be attenuated by the earth around the turbine building. In general the changes in the equipment above grade will be the most significant factor in skyshine although radiation scatter from other sources may be present. The equipment above grade includes steam piping, turbines, feedwater heaters, the upper portions of moisture separators and the transition between the turbines and condenser.
Based on Assumptions Items 1 through 3, a conservative estimate of the impact of EPU on skyshine is based on the increase in N-16 dose as a function of increased injection rate times the change in dose due to changes in steam transit time.
Using 14.8% increase in feedwater flowrate to estimate increased hydrogen injection rate and the effect of transit time at the exit of the # 15 FWH (1 7.1 % increase in estimated dose rate) yields a maximum skyshine source dose rate increase of 34.4% (1.148* 1.17 1).
The 2006 Annual Radiological Operating Report for MNGP reported the results of radiation monitoring for the plant. The report stated:
"Ambient radiation was measured in the general area of the site boundary, at an outer ring 4 - 5 mi distant from the Plant, at special interest areas and at four control locations. The means were similar for both inner and outer rings (1 6.5 and 15.6 mRem/9 1 days, respectively)....The mean for the control locations was 1 5.7 mRernl91 days. Dose rates measured at the inner and outer ring locations were similar Page 37 of41 Page 38 of 41 radiation is indicated."
The conclusion in the report is that there is no plant effect on ambient gamma radiation.
This would support an estimate that skyshine changes due to EPU will not have any impact on measured dose rates offsite.
The data shows a maximum difference between the inner and outer ring of 1.1 rnrem for a quarter. If this is taken as a measure of sky shine it represents a maximum of 4.4 mrem per 4
5 Offsite Dose Rate and Exposure Compliance with 10 CFR 20 5 20.1301, and 10 CFR 20 5 20.1302 Offsite Doses and Exposure Due to Storage, Transportation and Disposal of Radioactive Materials.
year at current conditions. Scaling this result by 34.4% is less than 6 mrem /yr. This is considered a conservative upper bound for offsite dose to skyshine at EPU conditions.
The average exposure due to gaseous emissions and liquid effluents to an individual are less than a total of 1 mrem per year. Adding this to the skyshine estimate of 6 rnredyr is a total of 7 mrem. As a result it is concluded that the maximum potential dose to any member of the public will remain well within the 40 CFR 190 limit of 25 rnredyr.
10 CFR 20 5 20.130 1, and 10 CFR 20 5 20.1302 establish a maximum dose rate in unrestricted areas of 2 mremlhr (0.02 mSv in one hour) and a maximum annual dose of 100 mrem (0.1 mSv). Based on the evaluations of doses due to gaseous emissions, liquid effluents, and skyshine in 3.3.2 Items 1,2, and 3, implementation of EPU is not expected to approach these limits.
Operation at EPU conditions will increase the need for truck transportation for disposal of solid radwaste by one truck per year. The solid radwaste system is designed to process, package, store, monitor, and provide shielded storage facilities for solid wastes to allow for radioactive decay andlor temporary storage prior to shipment from the plant for off-site disposal. The solid radioactive wastes are shipped off-site in vehicles equipped with adequate shielding to comply with Department of Transportation (DOT) regulations.
Code of Federal Regulations Title 10, Parts 20,61, 70 and 71 also apply. Based on this, inventory, no shielding berm, and continuous exposure to an individual at the closest site boundary. Adding this to the EPU estimate for operation of the plant (7 mredyr) gives a conservative total estimate of 15.9 mredyr. This meets the 25 mrem/yr limit of 40 CFR 190. ISFSI loading will occur over a period of years. Continued environmental monitoring will provide ample opportunity to detect problems and take action if dose rates from either source exceed expectations.
Page 39 of 41 General NRC Question
- 5) For all percentages used to describe the changes in dose and radiation levels at EPU described in Section 2.10, provide actual radiation and dose values.
NMC Response Responses to NRC Questions 1 through 4 above provide this information.
Acronym List for Enclosure 1 Short Form ALARA BOP BWR Ci CFR CGCS CLTP CLTR CPPU CR CRD CST DOT EDG EPU EQ GDC HP HPCI hr HWC HVAC HX lbm MCC MCO MNGP mrad mrem MWt N-16 NMC Description As Low as Reasonably Achievable Balance of Plant Boiling Water Reactor Curie Code of Federal Regulations Combustible Gas Control System Current Licensed Thermal Power CPPU Licensing Topical Report Constant Pressure Power Uprate Control Room Control Rod Drive System Condensate Storage Tank Department of Transportation Emergency Diesel Generator Extended Power Uprate Environmental Qualification General Design Criteria High Pressure High Pressure Coolant Injection System Hour Hydrogen Water Chemistry Heating, Ventilation and Air Conditioning System Heat Exchanger Pounds mass Motor Control Center Moisture Carryover Monticello Nuclear Generating Plant Millirad MilliRem Mega-watt - thermal Radioisotope of Nitrogen that is a major contributor to BOP dose rate.
Nuclear Management Company, LCC Page 40 of 4 1 NRC ODCM OLTP RCIC RG RHR RPV sec S JAE TIP RTP RWCU USAR Yr Nuclear Regulatory Commission Offsite Dose Calculation Manual Original Licensed Thermal Power Reactor Core Isolation Cooling System Regulatory Guide Residual Heat Removal System Reactor Pressure Vessel Second Steam Jet Air Ejector Traversing In-Core Probe System Reactor Thermal Power Reactor Water Cleanup System Updated Safety Analysis Report Year Page 41 of 41