ML19011A419
| ML19011A419 | |
| Person / Time | |
|---|---|
| Issue date: | 01/16/2019 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| Nathan Siu 415-0744 | |
| Shared Package | |
| ML19011A416 | List:
|
| References | |
| Download: ML19011A419 (23) | |
Text
References and
Background
1
References See separate handouts
- List of references
- List of acronyms and abbreviations 2
Continuous Probability Distributions
Background
3
Continuous Distributions - General Definitions and Useful Relationships
- Probability density functions (pdfs)
- Cumulative distribution functions 4
q
D0
< + D D
q
= q
= q
q q
1 < 2 q =
1 2
q = 2 q 1 q q
=
q
Continuous Distributions - General Definitions and Useful Relationships
- Complementary cumulative distribution functions
- Hazard functions 5
q
> q q
=
q q
D0
< + Dl>
D q
=
q 1 q q
= 1
q
Continuous Distributions - General Definitions and Useful Relationships
- Moments
- General
- Mean Value
- Variance 6
2 = 2 2
- Percentiles
- General: xa is the value that satisfies
- Median x0.50
=
=
0.50 =
0.50
Some Continuous Univariate Distributions Distribution Domain Density Function Cumulative Hazard Exponential X 0 ll 1 l l
Gamma X 0
G 1 Numerical Numerical Weibull X 0
1
1
1 Lognormal X 0 1
2 1
2
2 Numerical Numerical Gumbel Type I
- < X <
1
+ exp
1,
Uniform a X b 1
1
Beta 0 X 1 G +
G G 1 1 1 Numerical Numerical B-7
Some Continuous Univariate Distributions Distribution Domain Mean Variance Notes Exponential X 0 1
l 1
l2 Reverse J-shaped (mode at x = 0)
Gamma X 0
2 Reverse J-shaped (mode at x = 0) if a 1 Weibull X 0 G 1 + 1
2 G 1 + 2
2 Reverse J-shaped (mode at x = 0) if a 1 Lognormal X 0
+1 22
221 Mode:
Median:
Range Factor (X.95/X.05): 1.645 Gumbel Type I
- < X <
+ 0.5772 2
6 2 Mode: m Median: m - bln(ln(2))
Uniform a X b
+
2 2
12 Beta 0 X 1
+
+ 2 + + 1 Uniform if a = b = 1; reverse J-shaped (mode at x = 0) if a
< 1 and b 1; J-shaped (mode at x = 1) if a 1 and b < 1; unimodal with mode between a and b otherwise.
B-8
U.S. Nuclear Regulatory Commission
Background
9
NRC Mission The U.S. Nuclear Regulatory Commission licenses and regulates the Nations civilian use of radioactive materials to protect public health and safety, promote the common defense and security, and protect the environment.
- NUREG-1614 (NRC Strategic Plan) 10 The U.S. Nuclear Regulatory Commission licenses and regulates the Nations civilian use of radioactive materials to protect public health and safety, promote the common defense and security, and protect the environment.
- NUREG-1614 (NRC Strategic Plan)
The U.S. Nuclear Regulatory Commission licenses and regulates the Nations civilian use of radioactive materials to protect public health and safety, promote the common defense and security, and protect the environment.
- NUREG-1614 (NRC Strategic Plan)
NRC Organization Headquarters + 4 Regional Offices 5 Commissioners Staff and budget (FY 2018)
~3200 staff Total budget ~$940M Research budget ~$43M Website: www.nrc.gov Information Digest: NUREG-1350, V30 11 NUREG-1350, v30, 2018
Regulatory Approach Standard Reasonable assurance of adequate protection Principles
- Independence
- Openness
- Efficiency
- Clarity
- Reliability 12
How We Regulate 13
14 U.S. Nuclear Power Plants 99 plants (61 sites)
~99 GWe, ~805 GW-hr (2017) = 20% U.S. total Worldwide: 450 plants, 394 GWe capacity NUREG-1350, v30, 2018
Regulatory Documents
- Regulations - http://www.nrc.gov/reading-rm/doc-collections/cfr/
- Regulatory Guide (RG) - http://www.nrc.gov/reading-rm/doc-collections/reg-guides/
- Standard Review Plan (SRP) -
http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0800/
- NUREG Series Reports - http://www.nrc.gov/reading-rm/doc-collections/nuregs/
- Policy Statements - http://www.nrc.gov/reading-rm/doc-collections/commission/policy/
- Inspection Manual - http://www.nrc.gov/reading-rm/doc-collections/insp-manual/
15
Regulatory Documents - Examples 16 Regulation
- 10 CFR 50, Appendix A, Criterion 2
- Structures, systems, and components important to safety shall be designed to withstand the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches without loss of capability to perform their safety functions.
- RG 1.76, Design-Basis Tornado and Tornado Missiles for Nuclear Power Plants
- NUREG/CR-4461, Tornado Climatology of the Contiguous United States,
- RG1.221, Design-Basis Hurricane and Hurricane Missiles for Nuclear Power Plants
- NUREG/CR-7004 Technical Basis for Regulatory Guidance on Design-Basis Hurricane-Borne Missile Speeds for Nuclear Power Plants
- NUREG/CR-7005 Technical Basis for Regulatory Guidance on Design-Basis Hurricane Wind Speeds for Nuclear Power Plants SRP
- Standard Review Plan Chapter 3.3.1, Wind Loading
- Standard Review Plan Chapter 3.5.1.4, Missiles Generated By Tornadoes And Extreme Winds Backup
General Design Criterion 35 Emergency core cooling. A system to provide abundant emergency core cooling shall be provided. The system safety function shall be to transfer heat from the reactor core following any loss of reactor coolant at a rate such that (1) fuel and clad damage that could interfere with continued effective core cooling is prevented and (2) clad metal-water reaction is limited to negligible amounts.
Suitable redundancy in components and features, and suitable interconnections, leak detection, isolation, and containment capabilities shall be provided to assure that for onsite electric power system operation (assuming offsite power is not available) and for offsite electric power system operation (assuming onsite power is not available) the system safety function can be accomplished, assuming a single failure.
17
Safety Goal Policy Statement (51 FR 30028; August 21, 1986)
- Commission view on how safe is safe enough?
- Two quantitative health objectives (QHO) for the current generation of light water reactors
- The risk to an average individual in the vicinity of a nuclear power plant of prompt fatalities that might result from reactor accidents should not exceed 0.1% of the sum of prompt fatality risks resulting from other accident to which members of the U.S.
population are generally exposed
- The risk to the population in the area of nuclear power plant of cancer fatalities that might result from nuclear power plant operation should not exceed 0.1% of the sum of cancer fatality risks resulting from all other causes.
18
Safety Goal Policy Statement (cont.)
Based on CDC data,* the QHOs translate to:
- Accidents: 41.3 per 100,000 per year 41.3/100,000
- 0.001 = ~5E-07/yr
- Cancers: 185 per 100,000 per yr 185/100,000
- 0.001 = ~2E-06/yr
- Note: these are population-averaged risks to an individual 19
Safety Goal Policy Statement (cont.)
Surrogate safety goals*
- Worst case conditional probability of individual prompt early fatality (CPEF) for large early release = 3E-2**
- 3E-2 fatality risk/large early release
- Worst case conditional probability of latent cancer fatality (CPLF) from large release = 4E-03
- 4E-3 latent fatality/large release
- 1E-4 core damage/year
20
- See NUREG-1860, App. D for a justification
- Based on NUREG-1150 results for Surry (a PWR)
PRA Policy Statement (60 FR 42622; August 16, 1995) 1)
The use of PRA technology should be increased in all regulatory matters to the extent supported by the state-of-the-art in PRA methods and data and in a manner that complements the NRCs deterministic approach and supports the NRCs traditional defense-in-depth philosophy.
2)
PRA and associated analyses should be used in regulatory matters, where practical within the bounds of the state-of-the-art, to reduce unnecessary conservatism associated with current regulatory requirements, regulatory guides, license commitments, and staff practices. Where appropriate, PRA should be used to support the proposal for additional regulatory requirements in accordance with 10 CFR 50.109 (Backfit Rule).
3)
PRA evaluations in support of regulatory decisions should be as realistic as practicable and appropriate supporting data should be publicly available for review.
4)
The Commissions safety goals for nuclear power plants and subsidiary numerical objectives are to be used with appropriate consideration of uncertainties in making regulatory judgments on the need for proposing and backfitting new generic requirements on nuclear power plant licensees.
21
NRC R&D in the System 22 Adapted from National Research Council, World-Class Research and Development Characteristics for an Army Research, Development and Engineering Organization, National Academy Press, Washington, DC, 1996, ISBN 0-309-05589-X.
PROCESSING SYSTEM RECEIVING SYSTEM OUTPUT OUTCOMES INPUT MEASUREMENT AND FEEDBACK MEASUREMENT AND FEEDBACK R&D needs Resources
- People
- Funds
- Infrastructure
- Information Facts/Knowledge Recommendations Methods Models Tools Data Guidance Safety Security Environment MEASUREMENT AND FEEDBACK NRC/RES Activities Tests/experiments Surveys/reviews Technical analyses Development
Nuclear:
NRC U.S. Industry International Orgs Other:
U.S. Congress OGAs Technical Community General Public Policies Decisions Actions Information MEASUREMENT AND FEEDBACK Licensed Facilities Activities Other THE WORLD RESPONSES
NRC Information
- Website: www.nrc.gov
- Agencywide Document Access and Management System (ADAMS): http://adams.nrc.gov/wba/
- Jobs (USAJOBS): http://www.nrc.gov/about-nrc/employment/apply.html
- Status of Risk-Informed Activities:
https://www.nrc.gov/about-nrc/regulatory/risk-informed/rpp.html 23 Backup